Suction Bucket lid plate design and welding automation · welding automation Make Offshore wind...
Transcript of Suction Bucket lid plate design and welding automation · welding automation Make Offshore wind...
Suction Bucket lid plate design and
welding automation
Make Offshore wind turbines a competitive technology by making the
production processes of new foundation structures more flexible
By
JAVIER ZARAGÜETA GONZÁLEZ
MASTER THESIS
Department of Mechanical and Manufac-
turing Engineering
Fibigerstræde 16
DK - 9220 Aalborg Øst
Tlf. 45 9940 8938
www.m-tech.aau.dk
Title:
Suction Bucket lid plate design and welding
automation
Semester:
VT-4
Theme:
Master Thesis Project
Project period:
February 2017 - June 2017
ECTS:
30
Javier Zaragüeta González
Supervisors:
Morten Kristiansen (AAU)
Sigurd Villumsen (AAU)
Iñaki Díaz Garmendia (Tecnun)
Contact at Universal Foundations:
Soren A. Nielsen
Group Number:
3.120J
Number printed: 3
Pages: 70
Appendix: 22
Enclosures: 1
Synopsis
O�shore wind is potential technology to en-
sure the transition to a cleaner energy pro-
duction. However, even its energy generation
potential has been proven, this technology's
high costs and consequently low LCOE rate,
have left it in the background of the renewable
energy production.
An important item from this cost is the foun-
dation manufacturing. The low automation
on the manufacturing of foundations for o�-
shore wind turbines and the use of ine�-
cient technologies are the main causes of the
high costs of this technology. Nevertheless,
new emerging foundation technologies, like
the Mono Bucket, are being developed to
change this situation.
This project proposes a solution that searches
the reduction of the designing and welding
processes cost of one of the main components
of a Mono Bucket foundation. To ful�l this
task a solution consisting of two parts:
1. Parametric design of some structural
components.
2. De�nition of an automatic welding pro-
cess and an automatic robot program
generator.
The content of the report is freely available, but publication (with source reference) may only take place in
agreement with the author.
Preface
This report documents the Master Thesis composed by Javier Zaragüeta González on his
exchange program at Aalborg University during the period from the 1st of February to the
2ND of June 2017. The theme for the thesis is Manufacturing automation.
The project is completed under supervision of Associate Professors Morten Kristiansen
and Sigurd Villumsen, from Aalborg University, and Iñaki Díaz Garmendia from Tecnun,
University of Navarre. This project would not have been possible without the collabora-
tion of Søren A. Nielsen from Universal Foundations, who provided this project with very
interesting information about Mono Buckets and lid plates design.
Reading guide
Through the report source references in the form of the Harvard method will appear and
these are all listed at the back of the report. References from books, homepages or the
like will appear with the last name of the author and the year of publication in the form
of [Author, Year]. They can furthermore appear with speci�c reference to a chapter, page,
�gure or table.
Figures and tables in the report are numbered according to the respective chapter. In
this way the �rst �gure in chapter 3 has number 3.1, the second number 3.2 and so on.
Explanatory text is found under the given �gures and tables. Figures without references
are composed by the project group. As for �gures and tables, equations are also numbered
according to their respective chapter.
All the code �les, 3D models and RobotStudio �les and folders are available as an enclosure
of the project. This project provides the reader and user of the tools presented a user guide
that can be found on Appendix E. For further questions or support for the software tools,
write an email to the following address:
v
Table of contents
Chapter 1 Introduction 1
1.1 Europe 2020 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 O�shore wind energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter 2 Problem statement 11
2.1 Modular Suction Bucket components . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Design variability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Long manufacturing process . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4 Suction Bucket cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Chapter 3 Project goals 17
Chapter 4 Parametric design 19
4.1 Mono Bucket design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.2 Lid plate components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.3 Parametrization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4.4 SolidWorks' Equiation Manager . . . . . . . . . . . . . . . . . . . . . . . . . 30
Chapter 5 Automatic welding process 33
5.1 Welding station design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.2 Welding geometry determination . . . . . . . . . . . . . . . . . . . . . . . . 36
5.3 Welding parameters de�nition . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.4 Tool orientation de�nition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.5 Welding sequence de�nition . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Chapter 6 Lid Plate Generator 51
6.1 Parametric modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
6.2 Interaction with the lid plate 3D model . . . . . . . . . . . . . . . . . . . . 54
6.3 RAPID program generation . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
6.4 Welding characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Chapter 7 Economic study 61
7.1 Automatic welding cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
7.2 Cost - design variability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
7.3 Cost variation with diameter . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Chapter 8 Conclusion and perspectives 69
8.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
8.2 Further work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
List of Figures 71
vii
List of Tables 73
Bibliography 75
Appendix A Bulb plate sections
Appendix B Welding parameters
Appendix C RAPID program structure
Appendix D Lid plate welding time and cost breakdown
Appendix E User guide
Introduction 11.1 Europe 2020
Europe 2020 is the European Union's ten-year jobs and growth strategy launched in 2010
to create the conditions for smart, sustainable and inclusive growth. Five headline targets
have been agreed for the EU to achieve by the end of 2020:
• Employment
• Research and development
• Climate change and Energy sustainability
• Education
• Social inclusion and poverty reduction
As it can be seen, climate change and energy sustainability are both issues of great
importance that directly condition the growth and development of a country. Therefore,
the following objectives have been set:
� Reduction of the 20% (or even 30%, if the conditions are right)of the greenhouse gas
emissions (1990)
� 20% of energy from renewable
� 20% increase in energy e�ciency
Of all renewable energies, wind energy is the technology expected to provide the largest
contribution to the EU's 2020 renewable energy targets. It is planned that wind will
provide the largest contribution from all Renewable Energy Sources (RES), supplying
14.4% of total net electricity generation by 2020. Wind energy is mainly produce by
two di�erent technologies: Onshore and O�shore wind turbines. Both are experiencing a
signi�cant increase in the last years, but onshore has been always the dominant technology.
A share of 24% of total wind generation is produced from wind o�shore capacities in 2020
(33 GW installed capacity), but the share of o�shore wind declines thereafter, as the high
costs of wind-o�shore limit its market penetration [ICCS-NTUA, 2016].
However, the North Sea in particular is well suited to the development of o�shore wind
energy and will be key in increasing the EU's energy security and de-carbonising the
economy. Some countries like Denmark have even more ambitious goals that the one set
by the EU regarding energy. The Danish Energy Agency invests heavily in renewable
energy and is working towards two main goals[Gillis, 2014]:
� 2020 goal: 50% of the total electricity consumption supplied by wind power.
� 2050 goal: Energy and transport sector completely supplied by renewable energy.
1
VT3 1. Introduction
Denmark's progress in meeting these targets is remarkable. Last year, international press
praised Denmark's work in this regard, when the Nordic country broke world record
for wind power: "Denmark produced 42% of its electricity from wind turbines last year
according to o�cial data, the highest �gure yet recorded worldwide" [Neslen, 2016]. Since
EU member met on 2010 and �x the 2020 targets, Denmark has kept on increasing its
wind energy production and it is very likely to achieve its on 2020 goals. The following
graph shows this fact perfectly:
Figure 1.1: Wind power in Denmark [Neslen, 2016]
However, there are great opportunities in o�shore wind farms, as they can be much more
e�cient, specially in countries like Denmark:
"There is a huge potential for power generation on o�shore wind farms in the Danish
seas. Denmark has a geographical advantage in regards to cost-e�ective installation and
operation of large-scale o�shore wind farms in that the quality of the spatial, substrate
and wind conditions exceeds those of the neighbouring countries."[Association, 2014]
1.2 O�shore wind energy
The accomplishments described above are primarily achieved due to a high number of
onshore turbines. However within the recent years a new trend of moving the wind turbines
o�shore is evolving. O�shore wind technology is not something new. The �rst o�shore
wind project was Vindeby O�shore Wind Farm, installed o� the coast of Denmark in 1991.
Since then, bigger and bigger o�shore wind farms have been operating in shallow waters
around the world, mostly in Europe.
2
1.2. O�shore wind energy Aalborg University
Figure 1.2: Annual o�shore and onshore wind installations (MW) [Europe, 2016]
Figure 1.2 clearly show this trend of bringing wind turbines o�shore rather than building
onshore wind farms. This fact is mainly due to the following two reasons:
� Null a�ection to the population
As o�shore wind farms are built several kilometres far from the coast, both visual
and noise impacts decrease dramatically. Landscape perception and visual impact
are key environmental issues in determining wind farm applications related to wind
energy development as landscape and visual impacts are by nature subjective and
changing over time and location.
� Higher wind speeds
The higher strength and lower turbulences of marine wind makes it more suitable
for wind turbines. Danish Wind Industry Association estimates the wind resources
o�shore to be on average 50 % better than the ones obtainable onshore. The higher
winds has a considerable impact on the energy production of the turbines, e.g.
moving from 7.5 m/s to 9.5 m/s in wind speeds increase the energy production
with 40 %.
Even though the bene�ts of o�shore wind energy, its high cost is the main reason why
there is still a great di�erence between it and onshore wind and other renewable energy
sources. A common way to compare and express the overall cost of an energy source is
through the Levelized Cost Of Energy.
LCOE =Total cost over a lifetime
Energy produced over a lifetime(1.1)
3
VT3 1. Introduction
Figure 1.3: LCOE for all primary energy sources, Source: Siemens
From �gure 1.3 it can be concluded that, despite the potentials of o�shore wind energy, it
is still far from being considered a competitive energy source. To increase its LCOE, it is
fundamental to bring down the costs of this technology. To determine the potential areas
of improvement it is important to analyse the cost breakdown of the technology.
Figure 1.4: Capital cost breakdowns for typical onshore and o�shore wind systems [IRENA,2012]
As it can be seen in �gure 1.4, foundations and installation is the second most important
item on the budget of a o�shore wind system. Therefore, a reduction on the cost
foundations manufacturing and installation is a great way of making o�shore wind a more
competitive energy production technology.
1.2.1 Traditional o�shore foundations
One of the main components of every turbine to be installed o�shore is the foundation
where it lays on. The design of these structures has not received much attention, inheriting
designs from other sectors such as the Oil & Gas Industry. The traditional foundations
designs for o�shore wind turbines are the following ones:
� Monopile
� Tripod
� Jacket
� Gravity
4
1.2. O�shore wind energy Aalborg University
1.2.1.1 Monopile foundation
Monopile foundation structure is a relatively simple design by which the tower is supported
by a single reinforced concrete pile, either directly or through a steel transition piece, that
is stuck into the seabed. The standard method of installation of piled structures is to lift
or �oat the structure into position and then drive the piles into the seabed using either
steam or hydraulic powered hammers. Monopiles are currently the most commonly used
foundation in the o�shore wind market due to their ease of installation in shallow to
medium water depths. [Association, 2003a]
Figure 1.5: Monopile foundation components, Source: 4CO�shore
1.2.1.2 Tripod foundation
The tripod foundation draws on the experiences with light weight and cost e�cient three-
legged steel jackets for marginal o�shore �elds in the oil industry. From a steel pile below
the turbine tower emanates a steel frame which transfers the forces from the tower into
three steel piles. The three piles are driven 10 to 20 metres into the seabed depending on
soil conditions and ice loads. The advantage of the three-legged model is that it is suitable
for larger water depths. At the same time only a minimum of preparations are required at
the site before installation. [Association, 2003b]
Figure 1.6: Tripod foundation components, Source: 4CO�shore
5
VT3 1. Introduction
1.2.1.3 Jacket foundation
These foundations consist of a more complex structure of steel bars, which are �xed
symmetrically outside the main axis of the structure. This leads to a signi�cant decrease
of material costs. There are many variants of the three or four-legged jacket structure,
typically consisting of corner piles interconnected with welded tubular joints with diameters
up to 2 meters. The soil piles are driven inside the pile sleeves to the required depth to
gain adequate stability for the structure. [4CO�shore, 2013b]
Figure 1.7: Jacket foundation components, Source: 4CO�shore
1.2.1.4 Gravity foundation
The gravity type support structure is normally a concrete based structure which can be
constructed with or without small steel or concrete skirts. The ballast required to anchor
the foundation consists of sand, iron ore or rock �lled into the base of the structure with
adjustments in the designed base width to suit the soil conditions. The design will include
a central steel or concrete shaft for transition to the wind turbine tower. The structure
requires a �at base and for most locations will require some form for scour protection which
is determined during detailed design stage. [4CO�shore, 2013a]
Figure 1.8: Gravity based foundation components, Source: 4CO�shore
6
1.2. O�shore wind energy Aalborg University
1.2.2 New o�shore foundations
All the previous foundation types are the once that have been used for mainly all the
o�shore wind projects during the last years. As can be seen in �gure 1.9, the monopile
foundations have the dominant role on the o�shore wind foundations market
Figure 1.9: Current o�shore wind foundation type distribution, Source: WEU
However, as has been stated before, these foundation technologies absorb nearly a quarter
of all the budget and leave o�shore wind energy far from being competitive. To tackle
this problem some companies have been working on developing new foundations that can
bring down the price. The main innovative technologies are the following:
� Crane free gravity foundation
� Floating wind turbines
� Suction Bucket foundations
All the previous technologies have been developed to reduce the manufacturing, transport
and installation costs as much as possible. However, the Suction Bucket foundations have
to be highlighted among the others due to the fast development presented on the last years.
This technology is supported by the Carbon Trust's O�shore Wind Accelerator (OWA),
which is the world's largest industry collaboration focused on reducing the cost of energy
from o�shore wind through technology innovation.
1.2.2.1 Suction Bucket foundations
Suction Bucket foundations have been using for quite a long time in Oil & Gas industry,
but it has proved to be a very useful technology for o�shore wind foundations. They are
installed using a jet and suction system as the driving force. Lowering the pressure in
the cavity between the foundation and the seabed generates a water �ow, which lowers
resistance around the edge of the foundation's skirt. This reduces resistance and allows
seabed penetration. Once installed, it works like a common gravity foundation.
7
VT3 1. Introduction
Figure 1.10: Suction Bucket working principle, Source: Universal Foundation
This foundation technology has very interesting characteristics that make it a very
interesting alternative to traditional foundations:
� No seabed preparation needed
� Uses less steel than conventional piled foundations
� No pile driving needed, reducing the environmental impact during installation and
operation
� Can be removed for reuse or recycling by reversing the suction process
Nowadays, this technology has two main applications:
� Mono Bucket foundation
� Suction Bucket Jacket
Mono Bucket
On the one hand, Universal Foundation's Mono Bucket is an all-in-one steel structure
consists of a multi-shell foundation with vertical sti�eners, a robust lid and a shaft for
interfacing with the wind turbine. This design combines the main aspects of a monopile
and a suction bucket into one product. As the design involves an installation technique
whereby the verticality of the foundation is controlled by a lip-mounted jetting system,
there is no transition piece.
The technology has been developed over nearly a decade and after a number of successful
prototype installations for both met masts and turbine foundations, is now entering full-
scale production and supply to the commercial o�shore wind market.
8
1.2. O�shore wind energy Aalborg University
Figure 1.11: Mono Bucket, Source: LEEDCo
Suction Bucket Jacket
On the other hand, Suction Bucket Jacket has been designed by DONG Energy based on
ideas from the SPT O�shore foundation, which consists on a three-legged jacket structure
with three cup foundations that are anchored in the seabed using suction. So, this
technology can be considered as a combination of previously explained jacket foundations
and suction bucket technology.
This foundation has been designed for serial fabrication and will save costs across design,
fabrication, installation through to operation. The German o�shore wind project Borkum
Ri�grund 1 has been selected for testing this foundation before a new innovative design
can be considered for commercial projects.
Figure 1.12: Lifting of a jacket structure with suction buckets, Source: DONG Energy
9
Problem statement 2At the end of the previous chapter some innovative o�shore foundations have been
described. These technologies are thought to bring down the manufacturing and
installation cost of the foundations, e.g. using less raw material or facilitating the transport
from the harbour to the installation point. However, there is still a long way to reduce the
LCOE of the o�shore wind technology to make it a more competitive energy source.
In this chapter the main characteristics of a Suction Bucket foundation structure, the
modular design of Mono Bucket foundations in particular, will be analysed in order to point
this technology's strong and weak points. Knowing this, this project problem statement
will be stated.
2.1 Modular Suction Bucket components
The studied Suction Bucket consist on a new design. Currently, all the parts of the
structure were formed in a single piece. The new version consists on a modular structure
that tries to ease the manufacturing of the components and its transportation, but increases
the welding needed to assemble the foundation. The modular structure is composed by
three components:
Figure 2.1: Exploded view of a suction bucket [Villumsen, 2017]
11
VT3 2. Problem statement
1. Skirt plates
These plates are bended metal sheets which welded together to form the skirt of the
foundation. This part of the foundation is actually the one that is grounded into the sea
bead to form the foundation.
2. Lid plates
Lid plates enclose the cylinder formed by the skirt plates and connect them with the wind
turbine. The typical design consists on a main �at plate with some smaller plates welded
perpendicularly to act as reinforcement and ensure the mechanical properties of the part.
3. Legs
These components act as reinforcement by transmitting the loads from the wind turbine
to the foundation.
2.2 Design variability
The Suction Bucket is a very �exible foundation technology that can be installed in many
di�erent soils with little seabed preparation. This �exibility, however, makes the size of
the bucket very variable. All the components that are part of the structure have to be
scale every time the soil changes, what is quite common considering the size of the o�shore
wind farms.
Additionally, the large areas covered by the o�shore farms usually have some depth
variations, what also implies some size variations on the Suction Buckets situated at
di�erent depth in the same farm. For example, London Array wind farm's, situated near
the North Sea coast of the United Kingdom, covers an area of 122 km2 in which the seabed
depth varies as is shown in �gure 2.2:
Figure 2.2: Depth variation in the London Array wind farm area, [H. Burningham, 2008]
As it can be seen in �gure 2.2, the transition from a depth of 5 meters to 20 meters can
happen in ranges of tens of meters. This makes that from one turbine to the to the next
12
2.3. Long manufacturing process Aalborg University
the diameter of the Bucket foundation can vary almost to double.
Finally, it is important to remark that these foundations can be used by di�erent
manufacturers of wind turbines. This means that the diameter of wind turbine tower
might change from one company to another. What is more, every company has di�erent
models of wind turbines depending, specially on their power, which introduces another
variation fact in the design of the foundations.
2.3 Long manufacturing process
When the foundation parts have been scaled to the needs of every turbine model, soil
conditions and water depth, the manufacturing of the structure is carried out. The
productions process follows the next diagram:
Figure 2.3: Suction Bucket manufacturing process
As it can be seen in �gure 2.3, the manufacturing process consists on the sub-assembly of
all the components of the modular Suction Bucket described in 2.1 welding which are later
13
VT3 2. Problem statement
welded (represented by red boxes on the �ow diagram) to form the structure. So, even
if there are more processes involved(like bending and cutting, represented by green and
blue boxes), it can be said that welding is the predominant one. The welding precesses
described in �gure 2.3 are shown in the following �gure:
Figure 2.4: Welding paths types for the manufacturing of the Suction Bucket [Villumsen,2017]
From �gure 2.4 it can be said that all the welds needed for the union of the di�erent
components of the Suction Bucket consist on straight paths, which eases the welding
process. However, the thickness of the plates to be welded makes it necessary to carry out
several passes for every weld. If we add this fact to the size of the structure, which can
reach diameters of 19 meters, implies that welding is the what determine the production
cycle time, specially if the welds are carried out manually. What is more, taking into
account that some parts, like the lid plate, need a sub-assembly before beginning with the
whole assembly of the structure, the number welding hours increase even more.
Table 2.1: Deposit rates of di�erent welding technologies, Source: TWI
Welding technologyDeposit rate [kg/h]
min max
MMA 0.4 5.5
GMAW 0.6 12
FCAW 1.0 15
SAW 3 16
14
2.4. Suction Bucket cost Aalborg University
2.4 Suction Bucket cost
After the quick overview of the two main problems of the production of a single Suction
Bucket explained on the previous sections, it can be concluded that the price of every
Bucket is not low enough to make this a competitive technology. What is more, the
transportation and inspection costs must be sum to the manufacturing cost, resulting in
a breakdown of the cost shown in the following �gure:
Figure 2.5: Estimated cost of a single suction bucket [Villumsen, 2017]
It is important to take into account that the manufacturing cost is nearly a quarter of the
hole budget of every modular Mono Bucket. This is mainly due to the facts presented in
the previous points of the chapter:
� Great amount of welding process needed due to the modular design
� Continuous design changes due to external conditions
� Size and thickness of the steel plates used in the structure
� High ine�ciency of carrying out all the welding manually
� Need of sub-assemblies
In conclusion, all these design and manufacturing problems do not allow the Suction Bucket
technology to break into the market of o�shore wind turbine foundations. The LCOE
reduction of the o�shore wind technology can come from the implantation of the Suction
Bucket as the predominant foundation technology, but before that all this problems have
to be tackled. To sum up, the problem statement of this project is stated as:
How could the design and manufacturing time of a Suction Bucket be reduced
to make a more economical and reduce its LCOE?.
15
Project goals 3From the previous chapter it can be concluded that the production of Suction
Bucket foundation structures is a small-batch-size process. That implies that product
characteristics change from order to order and the number of identical products in an
order is small or single. This means that the design of the product and the production
preparation have to be rede�ned every time a new order is placed.
Furthermore, the manufacturing time needed to produce each foundation structure makes
the Suction Bucket foundations in particular and o�shore wind energy in general non-
viable technologies if they are compared with other energy production technologies. As
was explained on the previous chapter, welding is the determinant process of the modular
Mono Bucket's manufacturing, so this project will be focused on improving the e�ciency
and productivity of this process. Manual welding of the di�erent structural components
should be substituted by a more e�cient manufacturing process.
Taking this two facts into account, the question stated on the problem statement can be
particularized in more detailed questions:
� How can the design process be simpli�ed?
� How can the generation of manufacturing data be automatized?
� How can the welding be more �exible?
This project proposes a solution focused only on the lid plates of the foundation structure,
to serve as an starting point for future development to the whole structure. Knowing this
and taking the previous questions as a guide the main objectives of this project can be
stated:
Design of a 3D parametric model of the lid plate
To enable a fast resizing and modi�cation of the design of the lid plate, a parametric
model would be developed in SolidWorks. This model will ask the user to select a model
of lid plate from a prede�ned list and will scale and modify a base model based on the
geometrical characteristics of that selection.
Development of an automatic manufacturing data generation tool
Once the geometry of the model has been correctly scaled, welding data will be generated
by the means of welding points, paths and parameter de�nition. For this purpose, a
software tool will be programmed using C# language that will interact with the 3D model
of the lid plate to de�ne all this data.
17
VT3 3. Project goals
De�nition of an automatic manufacturing process based on a robotic arm
With all the data from the previous steps, a robot programming will be carried out in
order to make the manufacturing process completely automatic. This programming will
be automatically generated from the C# programmed tool and uploaded to ABB's o�-line
simulation and programming software; RobotStudio.
To accomplish these three objectives the �ow diagram shown in �gure 3.1 will be followed:
Figure 3.1: Project �ow diagram
In conclusion, this project searches the reduction of the design and manufacturing costs
of the Suction Buckets by proposing a faster and more e�cient design and manufacturing
processes. So, to make sure that the proposed solution is a e�cient way of reducing the
costs of producing each modular Mono Bucket and economic study will be carried out. In
this study the costs of traditional and automatic manufacturing processes will be compared
and how di�erent designs of Suction Bucket's lid plate a�ect the manufacturing cost.
18
Parametric design 4This chapter describes the design and geometry of lid plates from a modular Mono Bucket
foundation. Once the geometry has been analysed, the relations between the di�erent
dimensions of this component will be de�ned to geometrically relate all the available
designs of lid plate studied in this project. This will enable the parametrization of the
lid plate which will simplify its design, reducing the time needed to carry out the 3D
design of every lid plate model.
4.1 Mono Bucket design
While designing modular Mono Bucket foundations there are a lot of aspects to consider
to size all the components of the structure. Aspects such as the forces introduced by the
maritime environment and the wind turbine or the conditions of the soil are critical to
determine the loads that the foundation structure has to hold. So, to correctly design the
Bucket complicated mechanical calculations have to be carried to.
Universal Foundation, the company responsible of the design of the Mono Bucket
foundations, has developed a calculation tool based on Matlab called Fast Bertha that
calculates the loads that the foundation has to withdraw in every case and obtains all the
geometrical parameters needed to design the foundation. The main task pane of this tool
is shown in �gure 4.1:
Figure 4.1: FastBertha tool task pane, Source: Universal Foundation
19
VT3 4. Parametric design
As the focus of this project is not to carry out all the mechanical calculations that the
FastBertha does to design each Mono Bucket model, some models obtained from this tool
would be analysed. In the following table, all the design variations that will be studied in
the project are shown:
Table 4.1: Lid plate design variations, Source: Universal Foundation
Model Lid pressure [KPa] Do [m] Di [m] Bulb plates α [◦]
MB9_200 200 9 2 8 20
MB9_300 300 9 2 8 20
MB9_400 400 9 2 8 20
MB10_200 200 10 2 8 20
MB10_300 300 10 2 8 20
MB10_400 400 10 2 8 20
MB10_400_6 400 10 2 6 30
MB10_400_12 400 10 2 12 15
MB10_400_15 400 10 2 15 12
MB11_200 200 11 2 8 20
MB11_300 300 11 2 8 20
MB11_400 400 11 2 8 20
MB12_200 200 12 2 8 20
MB12_300 300 12 2 8 20
MB12_400 400 12 2 8 20
MB12_400_12 400 12 2 12 15
MB12_400_15 400 12 2 15 12
These models are typical designs of Mono Buckets that have already been installed or are
going to be installed soon in some of Universal Foundation's projects. As it can be seen in
table 4.1, the main variables that determine the Mono Bucket model are the outer diameter,
lid pressure and lid angle. These parameters have an important roll on determining the
characteristics of the Mono Bucket and are subject to a great variability as was explained
in the previous chapter.
In order to answer the need for designing parts which size has to be rede�ned constantly,
this project proposes the development of a parametric design. The �rst step on making the
design of the parts from the foundation structure more �exible is to analyse the target part
and determine how it has to be rescaled. From all the components of the Mono Bucket,
the lid plate is the one whose manufacturing is most easily automated, so it is the chosen
part to build a �rst parametric design.
20
4.2. Lid plate components Aalborg University
4.2 Lid plate components
Lid plates are responsible for closing the top of the foundation structure and are connected
to the rest of the parts, making them vital elements of the foundation. Each lid plate is
formed by the assembly of multiple parts, shown in �gure 4.2
Main plate1. Bulb plates2. Lateral plates3.
Figure 4.2: Geometrical parameters of the main plate
Before carrying out any design, is important to study the geometry of each of the
components of the lid plate.
4.2.1 Main plate
The main plate is responsible for supporting the remaining parts that form the lid plate.
It has the shape of a circular annular sector and is de�ned by the following parameters:
Figure 4.3: Geometrical parameters of the main plate
21
VT3 4. Parametric design
α : Lid plate angle
Do : Outer diameter
Di : Inner diameter
t : Plate thickness
Both diameters; Do and Di de�ne the annular sector. These features depend mainly on
the seabed depth where the Suction Bucket is going to be installed and the wind turbine
that is going to be put on the top of the foundation.
On the other hand, the lid plate angle α de�nes the width of the lid plate. This parameter
is de�ned by the number of legs that are going to be installed to connect the foundation
with the wind turbine. As the number of legs increases, the angle α will be reduced and
consequently, the number of lid plates need to complete the lid of the Suction Bucket will
increase too.
4.2.2 Lateral plates
These plates consist of a simple rectangular shape plate with two 45º cuts on each end.
They are positioned parallel to the edges of the main plate and are responsible of linking
all the bulb plates together to ensure the improvement of the mechanical properties of the
lid plate.
(a) Lateral plates layout
(b) Detailed view of the lateral plates' cut
Figure 4.4: Lateral plates
22
4.2. Lid plate components Aalborg University
4.2.3 Bulb plates
Bulb plates are installed on top of the main plate and between the lateral plates, arranged
in a pattern in which the separation between bulb plates decreases as they move away
from the inner part of the piece. This arrangement can be seen in �gure 4.5:
Figure 4.5: Bulb plates layout
These plates are standardized structural pro�le commonly used for ship building and other
constructive applications. The dimensions that give the name to each model of bulb plate
are the height (bmm) and thickness (tmm) of the plate. So, a 180x10 bulb plate model,
would have a height of 180 mm and a thickness of 10 mm. These two dimensions are
display in �gure 4.6:
Figure 4.6: Bulb iron section and main dimensions
All the bulb plate models used for the di�erent lid plate designs are picked from a
manufacturer's catalogue that can be found in Appendix A.
The main objective of these plates is to improve the mechanical properties of the part
and for that is important to de�ne correctly the position of each one of them. Depending
on the operating and environmental conditions in which the foundation is going to be
installed, the section model selected varies. As the mechanical stresses that the foundation
has to withstand increase, the selected model will have bigger and more robust sectional
properties. Additionally, if the diameter of the bucket increases the separation between
bulb plates will vary too.
Going into detail of the design of the lid plate, FastBertha calculates the previously shown
parameters plus the bulb plate disposition to completely de�ne the lid plate (see �gure
23
VT3 4. Parametric design
4.7). This disposition depends barely on the diameter of Bucket or the outer diameter the
lid plate, as can be seen in table 4.2:
Figure 4.7: FastBertha lid plate results example, Source: Universal Foundation
In this project only 8 bulb lid plates will be designed and analysed to focus on how the
variability of other parameters like the lid angle or the Bucket diameter a�ect the design
and the manufacturing of the lid plate. Knowing this, in the following table the position
of each one of the eight bulb plates on every lid plate model can be seen:
Table 4.2: Bulb plates possible disposition [mm], Source: Universal Foundation
Do = 9 mDo = 10 m
Do = 11 mDo = 12 m
30◦ 20◦ 15◦ 12◦ 20◦ 15◦ 12◦
0-1 810 830 930 960 980 1040 1160 1200 1220
1-2 490 500 560 580 590 630 700 720 730
2-3 420 430 480 500 510 540 600 620 630
3-4 390 400 440 460 470 500 560 580 590
4-5 320 330 370 380 390 420 460 480 490
5-6 290 300 330 350 350 380 420 430 440
6-7 290 300 330 350 330 380 420 430 440
7-8 230 230 260 270 270 290 330 340 340
What is more, the section of the bulb plate changes depending on its position and the lid
plate model selected. The selection of each bulb plate is based on the calculation carried
out by FastBertha and the available bulb plate models (see Appendix A). So, all the bulb
plates required for each one of the lid plate models obtained from this tool have been saved
on a Excel data base, so, the program can easily acces that date. The bulb plate sections
selected for every model are displayed in table 4.2:
24
4.3. Parametrization Aalborg University
Table 4.3: Bulb plate sections of every lid plate model [mm x mm], Source: UniversalFoundation
Bulb plate
Model 1 2 3 4 5 6 7 8
MB9_200 140x8 160x7 160x9 180x8 180x8 180x10 180x10 200x9
MB9_300 180x8 180x8 200x9 200x9 200x10 220x10 220x10 220x11.5
MB9_400 180x10 200x9 220x10 220x10 220x11.5 240x10 240x11 260x10
MB10_200 160x8 180x8 180x9 200x9 200x9 200x11.5 220x10 220x10
MB10_300 180x10 200x9 220x10 220x11.5 240x10 240x11 240x11 260x10
MB10_400 200x10 220x10 240x10 260x10 260x10 280x11 280x11 280x11
MB10_400_6 260x12 280x11 300x13 320x13 340x12 340x14 320x13 430x17
MB10_400_12 160x9 180x8 200x9 200x11.5 220x10 220x10 220x11.5 200x11.5
MB10_400_15 140x8 160x7 180x8 180x8 180x9 200x9 200x9 180x8
MB11_200 180x8 180x10 200x10 220x10 220x10 240x10 240x10 240x11
MB11_300 200x9 220x10 240x10 260x10 260x10 280x11 280x11 280x11
MB11_400 220x10 240x10 260x11 280x11 300x11 300x12 300x13 320x12
MB12_200 180x10 200x9 220x10 240x10 240x11 260x10 260x11 260x12
MB12_300 220x10 240x10 260x10 280x11 280x12 300x11 300x12 320x12
MB12_400 240x10 260x10 300x11 300x13 320x12 340x12 340x12 340x14
MB12_400_12 200x9 220x10 240x11 260x10 260x10 280x11 280x11 260x10
MB12_400_15 180x8 180x9 200x10 220x10 220x10 240x10 240x10 200x11.5
As it can be seen in table 4.2, in every model, as the bulb plate is positioned further from
the inner diameter its size increases. Additionally, the size of the bulb plates increases
with the bucket diameter, the lid pressure and the lid angle. So, for bigger lid plates (α ↑or Do↑) and for deeper seabed applications (Lid pressure↑) the used bulb plates would be
bigger.
Knowing all the characteristics of a lid plate and having all the data provided by FastBertha
it is possible to look for the equations and relations that will enable the parametric design
of all these lid plate models.
4.3 Parametrization
To start with the parametric modelling, a base model has to be de�ned. In this case,
the smallest lid plate model (MB9_200, see characteristics in tables 4.1, 4.2 and 4.3) will
be used as the base model and will be scaled based on the user's needs. To de�ne the
geometry of the 3D model of the base model there are a series of geometrical parameters
that have to be determined. Figure 4.8 shows the most important dimensions of the lid
plate:
25
VT3 4. Parametric design
Figure 4.8: Geometrical parameters of the lid plate
α : Lid plate angle
Ro : Outer radious
Ri : Inner radious
d1 - d8 : Distance between bulb plates
To determine all these properties it is important to calculate the mechanical stresses that
the structure has to withdraw in each application. However, there is not a single solution
for each case, because there are more than one way of improving the mechanical properties.
For example, it can be done by increasing the size of the lid plate by increasing its outer
diameter or by increasing the number of bulb plates.
All the models obtained using Universal Foundation's FastBertha tool are di�erent design
options for multiple working environments. The �rst decision that has to be taken is the
size of the bucket. This fact will determine the design of the rest dimensions. On the one
hand, the disposition of the bulb plates on top of the main plate depends on the size of
the bucket (table 4.2) . The relation between the distances between bulb plates on a base
model of 9 meter of diameter and distances on buckets with a bigger diameters can be seen
in �gure 4.9:
26
4.3. Parametrization Aalborg University
Figure 4.9: Distance between bulb plates relation
As it can be seen, the relation is almost linear and can be expressed using the following
equations:
d10m = 1.1525 · d9m − 4.2797 (4.1)
d11m = 1.2775 · d9m + 5.0953 (4.2)
d12m = 1.4256 · d9m + 3.8676 (4.3)
However, looking at table 4.2 it can be realized that the disposition of the lid plates also
changes with the lid angle. Once more the relation of the distances between the bulb plates
on 10 m and 12 m diameter Mono Buckets with di�erent lid angles and a base model of 9
m diameter and a lid angle 20◦ is graphed:
27
VT3 4. Parametric design
Figure 4.10: Distance between bulb plates relation Do = 10 m, α 6= 20◦
This time again the linear relations are easily identi�ed. The equations of the lines shown
in �gure 4.11 are the following:
d10m,30◦ = 1.0245 · d9m,20◦ + 0.0466 (4.4)
d10m,15◦ = 1.1807 · d9m,20◦ + 3.0582 (4.5)
d10m,12◦ = 1.2150 · d9m,20◦ − 3.3421 (4.6)
28
4.3. Parametrization Aalborg University
Figure 4.11: Distance between bulb plates relation Do = 12 m, α 6= 20◦
As in the previous cases, the relation of bulb distances is linear and is expressed by the
following equations:
d12m,15◦ = 1.4771 · d9m,20◦ + 1.7669 (4.7)
d12m,12◦ = 1.5017 · d9m,20◦ + 1.8136 (4.8)
On the other hand, each model's bulb plate selection is unique and depends on the outer
diameter, the lid pressure and the lid angle. To allow a easy manipulability of the bulb
plate set of each lid plate model a data base has been created on Excel.
As it was said in the previous section, bulb plates are standardized pro�les selected from
distributor's catalogues and their main characteristics are the height and the thickness of
the plate. However, as it can be seen in �gure 4.12 there are some more dimensions that
have to be determined to de�ne a 3D model of every lid plate.
29
VT3 4. Parametric design
Figure 4.12: Dimensions of a bulb plate section, , Source: British Steel
Just by taking a look at the catalogue available at Appendix A, it can be realized that the
radius r and the distance c only depend on the height of the bulb plate. So, taking the
smallest lid plate section as a reference a linear relation can be stated to determine these
two dimensions for a given bulb plate height. These relations are de�ned by the following
equations:
c =b− 140
20· 3 + 19 (4.9)
r =b− 140
20+ 5 (4.10)
So, just by knowing the height and the thickness of the bulb plate its section is completely
de�ned.
4.4 SolidWorks' Equiation Manager
To ensure the correct resize and modi�cation of the base model, the equations that relate
the di�erent dimensions have to be introduced into the 3D design software, SolidWorks
in this case. For this purpose SolidWorks' Equation Manager is used. This tool allows
the user to state relations between di�erent dimensions of the model. All the equations
previously de�ned are introduced in the manager, so every time a dimension changes all
the other dimensions related to it will change too.
Additionally, a series of Custom Properties are set to de�ne each lid plate model. These
properties are unique for each model, its value will be determinate when the lid plate
model is generated and will be introduced in the equations to obtain all the remaining
dimensions of the lid plate. The de�ned custom properties are the following:
30
4.4. SolidWorks' Equiation Manager Aalborg University
� LidModel: Model of lid plate selected
from the list
� InnerD: Inner diameter (same as the
wind turbine to be installed)
� OuterD: Outer Bucket diameter
� LidAngle: Angle formed by the lid
plate and its centreline
� NumberBulbs: Number of bulb
plates (in this case always 8)
� LidPressure: Pressure that the en-
tire lid has to withstand
� Thickness: Main plate thickness
� LateralHeight: Lateral plate height
� Bulbm: Slope of the inter bulb dis-
tance relation
� Bulbn: Intercept of the inter bulb
distance relation
� Bh1-Bh8: Bulb plate heights
� Bt1-Bt8: Bulb plate thickness
With all these Custom Properties and all the equations stated previously a lid plate base
3D model is designed in SolidWorks. As was said before, this base model has the dimensions
of the smallest lid plate model from table 4.1; MB9_200. These parametrization equations
are introduce to the Equation Manager using the interface shown in �gure 4.13:
Figure 4.13: SolidWorks's Equation Manager
This way, a completely de�ned 3D parametric model is designed in SolidWorks. It will
wait for the user to introduce the required values of the Custom Properties to de�ne the
desired lid plate model 3D design.
31
Automatic welding process 5The welding of the Mono Bucket's lid plate consist mainly, on a series of linear welds
to join the smaller components to the main plate. However, these welding paths' length
changes depending on the lid plate design, so the proposed automatic solution should be
able to quickly rede�ne the welding targets and be �exible enough to manufacture all the
di�erent lid plate designs introduced by the user. The solution proposed in this chapter
has been developed to tackle both problems, using an automatic weld path de�nition and
a proper working cell design.
5.1 Welding station design
With a diameter that can exceed 12 meters, the work station need to produce lid plates
needs a big working area and a tool that is able to reach all the welding points. For this
purpose, this project presents a solution based on a robot arm mounted on a gantry crane
that enlarges its reachability and working area.
5.1.1 Robot and tool selection
The robot arm selected for this application is the IRB 4600-40/2.55 model, selected from
ABB 's catalogue. IRB 4600 robot series is a robotic arm commonly used for welding
applications and model 40/2.55 is the one with the largest working range from the series,
so it is a good choice for the working cell needed to produce lid plates.
Figure 5.1: IRB 4600-40/2.55 working range, Source: ABB
33
VT3 5. Automatic welding process
On the other hand, the tool chosen to be installed in the robot is the model PK 500. This
welding torch is the one which geometry best suits the welding orientations needed to carry
out in the lid plate from all the models available in the RobotStudio library.
Figure 5.2: PK 500 welding torch installed on a IRB 4600 robot in RobotStudio
5.1.2 Gantry crane design
The gantry crane used in this application would work as X and Y auxiliary axes to enlarge
the working area of the robot. With these mechanism the manufacturing of the lid plate
is carried out mainly on a horizontal plane, making it easy to position all the components
on top of the main plate. In addition, the support structure to hold and correctly position
the plate is much simpler than if another mechanism displacement is chosen. Additionally,
gantry cranes are commonly used in industry, so the implementation of this solution can
be carried out using an existing installation or at least it should be easier to implement in
a common factory than other solutions.
To represent the gantry crane a simpli�ed design has been carried out which basically
consist of three elements: X axis, Y axis and Joint. Both axes will consist of two prismatic
bodies which length has been set so that the the biggest lid plate model �ts on the work
area and connected by a simple double "U" shape joint. In this case, the largest lid plate
has a length of approximately 6 meters, so the gantry crane axes have been designed with a
length of 10 meters to be ensure that this and lager lid plate models would be manufactured
without problems. The representation of the gantry crane is shown in �gure 5.3:
Figure 5.3: XY Crane in RobotStudio
34
5.1. Welding station design Aalborg University
Once the components of the crane have been designed the mechanism characteristics are
de�ned. This consists of de�ning the moving limits of each axis and the frame where the
robotic arm is going to be attached. On the one hand, the moving limits of each axis
are 8 meters for the X axis and 7 meters for the Y axis. These dimensions of the axes
has been set to be able to �t all the available Mono Bucket design, leaving room if the
manufacturing of bigger lid plate designs is implemented in the future.
On the other hand, the position and arrangement of the frame (see �gure 5.4b) was selected
to ensure a easy translation of the welding points from the 3D model to the welding
station. Due to the arrangement of the welding cell, it is important to correctly de�ne the
coordinates origin. This will allow to correctly reference the welding coordinates obtained
from the parametric 3D model and generate the welding paths.
(a) Lid plate origin
(b) Work station origin
Figure 5.4: Coordinates origins
35
VT3 5. Automatic welding process
The coordinates origin of the welding station is situated at the base of the robot when
the XY is at home position, as is shown on �gure 5.4b. On the other side, remembering
from 6.2, the welding coordinates obtained from the 3D model and shown in the report
are referred to the center of the inner circle of the annulus (�gure 5.4a).
To �t those welding points into the working area of the station designed in RobotStudio,
some translations and a rotation have to be applied to each point. The rotation consist of
a 180◦ turn around the y axis and can be represented by the following rotation matrix:
Ry =
cos(180◦) 0 sin(180◦)
0 1 0
−sin(180◦) 0 cos(180◦)
=
−1 0 0
0 1 0
0 0 −1
(5.1)
Additionally, some translations are needed to position the lid plate on a reachable area for
the robot. So, these translations are added to the previous matrix:
T = 1000 ·
−1 0 0 1
0 1 0 3
0 0 −1 2, 3
0 0 0 1
(5.2)
Using this transformation matrix the coordinates from the 3D model can be translated to
the welding station following the next expression:Xstation
YstationZstation
1
=
Xlid
YlidZlid1
· 1000 ·−1 0 0 1
0 1 0 3
0 0 −1 2, 3
0 0 0 1
[mm] (5.3)
5.2 Welding geometry determination
Taking into account the geometry of the lid plate and its components de�ned in chapter 4,
the main welding points that de�ne the welding sequence of the process can be determined.
Looking at the 3D model of the part it is quickly observed that all the welds needed to
build the lid plate are straight lines which can be di�erentiated in three groups:
� Lateral - main plate welds
� Bulb - main plate welds
� Bulb - lateral plate welds
The �gure 5.5 shows an example of the di�erent types of welds on a lid plate model:
36
5.2. Welding geometry determination Aalborg University
Figure 5.5: Weld types
Knowing that all these weld paths are de�ned by lines, just by de�ning the starting and
the end points of each line would be enough to determine the welding. So, the �rst step is
to de�ne all the points required to obtain the weld geometry.
For the case of the bulb - main plate welds and the bulb - lateral plate welds the start and
end points of these lines are labelled as is shown in the next �gures:
(a) Bulb weld start points and left bulb -lateral weld points labelling
(b) Bulb weld end points and right bulb -lateral weld points labelling
Figure 5.6: Bulb welding points labelling
37
VT3 5. Automatic welding process
The welding of each bulb plate consist of two horizontal welds; front and back. They are
de�ned by two points that are coincident with the intersection of the bulb, lateral and
main plates. For example, the front bulb weld is de�ned by BulbStart and BulbEnd.
On the other hand, the welds between the lateral and the bulb plates are de�ned by two
vertical welds; front and back. The start point of these welds coincides with the end of
the lateral plate and the end point coincides with the start or end of the bulb welds. In
the case of the front left bulb - lateral weld, it is de�ned by the points LeftBulbLat and
BulbStart (see �gure 5.7a).
(a) Lateral plate weld start points la-belling
(b) Lateral plate weld end points la-belling
Figure 5.7: Lateral welding points labelling
On the other side, the lateral plates are welded on the both sides. The outer welds consist
of a single weld de�ned by an start and end point (LateralStart and LateralEnd). However,
the de�nition of the inner weld is completely di�erent. They are composed by multiple
segments between the start (InLateralStart) and the end (InLateralEnd) delimited by the
bulb plates.
So, to ful�l the right lateral weld the �rst segment is de�ned by InLateralStart and BulbEnd.
After that, all the segments delimited by bulb plates are de�ned by BackBulbEnd and
BulbEnd point of the next bulb plate. Finally, the last segment is de�ned by BackBulbEnd
point of the last bulb plate and InLateralEnd.
5.2.1 Intermediate points de�nition
Nevertheless, just with these points and the ones de�ned previously is not enough to carry
out a correct welding of the lid plate. Some intermediate points have to be designed to
avoid any possible collision between the welding tool and the working piece.
To ensure a correct transition from the front to the back weld of bulb plates, two
intermediate points are de�ned. This transition can start at LeftBulbLat point or at
RightBulbLat point, depending on how many passes are needed to complete the front
welding, but the de�nition of these two intermediate points is equivalent for both
cases. Figure 5.8 shows the case where the transition starts at LeftBulbLat and ends
at BackLeftBulbLat :
38
5.2. Welding geometry determination Aalborg University
Figure 5.8: Examples of bulb weld transition intermediate points
Following �gure 5.8, in the case that the robot �nishes welding the front of the bulb plate
on the left side of it (LeftBulbLat), to carry out the transition to the back side of the plate
the sequence is the following one:
LeftBulbLat → BulbStartInter → BackBulbStartInter → BackLeftBulbLat
More transition points are required for the transition between lateral plate welds. In this
application, the transition between lateral plate welds happens when the right outer lateral
weld is carried out, ending at LateralEnd point of that plate. Then the robot has to move
to LateralEnd point of the other plate. To ensure that this transition is done correctly the
following intermediate points are de�ned:
Figure 5.9: Lateral weld transition intermediate points
39
VT3 5. Automatic welding process
So, by de�ning the LateralEndInter points the collision with both the lateral and bulb
plates is avoided.
5.2.2 Welding coordinates de�nition
Now that all the di�erent points required to de�ne all the welds have been de�nes, the
geometrical relations between their coordinates have to be de�ned. These relations will
help to de�ne all these points during the automatic robot program generation.
To state these geometrical relations, the Custom Properties de�ned in chapter 4 are used.
This way, when these properties are modi�ed in the 3D parametric model of the lid plate,
this modi�cation will be automatically translated to the geometrical relations between
weld points. So any change on the lid plate dimensions will mean a rede�nition of the weld
point coordinates to �t the new shape of the part.
Back bulb weld points
In the case of the back bulb weld points, a relation with the front weld point can be stated
knowing the bulb plate thickness (Bti) and the lid plate angle (α) (see �gure 5.10).
Figure 5.10: Front and back bulb points
Applying trigonometry and using the two Custom Properties, the translation from the
front to the back weld points can be expressed using the following equation:
Xback
YbackZback
=
Xfront
YfrontZfront
+
Bti∗ ±Bti · tanα
0
∗
+ Left,−Right (5.4)
The sign of the translation on the Y axis depends on the side of the bulb plate where the
point is situated. For the case of the start point (BackBulbStart), which is on the left side
of the plate, the translation will have a positive sign, because BackBulbStart point's Y
coordinate is bigger than the front point's (see �guere 5.10). On the other side, due to the
axes arrangement the sign of the translation for the end point will be negative.
40
5.2. Welding geometry determination Aalborg University
Bulb - lateral weld points
As it was said at the beginning of the section, the start points of the bulb - lateral welds
coincide with the star or end point of the weld points. These welds consist on vertical
lines that have a length equal to the height of the lateral plate, which (remembering from
chapter 4) is a Custom Property (LateralHeight) of the 3D parametric model.
Knowing this, to obtain the points that de�ne the welds between the bulb and the lateral
plates the following translation on the Z direction is necessary:Xbulblat
YbulblatZbulblat
=
Xbulb
YbulbZbulb
+
0
0
LateralHeight
(5.5)
Bulb weld intermediate points
The intermediate points de�ned to avoid the collision of the torch with bulb plates each
time that it makes the transition from the front to the back weld of the bulb plate some
intermediate points can be related to the bulb weld point between whom they de�ne its
transition.
(a) Left view (b) Top view
Figure 5.11: Left and top views of a bulb plate with the intermediate points displayed
As can be seen in the example shown in �gures 5.12a and 5.12b, a translation in all the
axes has to be applied to obtain the coordinates of the intermediate points from the ones
from the bulb welds. To ensure that the robot won't collied against the bulb plate and
that this intermediate points are reallocated every time the lid plate model changes the
Custom Properties of the bulb height (Bhi) is used.
Xbulbinter
YbulbinterZbulbinter
=
Xbulb
YbulbZbulb
+
±Bh∗i±Bh∗∗i1, 5 ·Bhi
∗ + Front,−Back∗∗ +Right,−Left
(5.6)
41
VT3 5. Automatic welding process
In this case, as for the back bulb weld points, the sign of the Y and X changes depending
on the reference point that is being used to de�ne the coordinates of the intermediate
point.
On the one hand, the sign of the X translation is positive if the intermediate point is
related to a front weld point (BulbStart or BulbEnd) and negative if it is related to a back
one (BackBulbStart or BackBulbEnd). On the other, the translation in Y will be negative
if the intermediate point de�nes a transition on the left side of the bulb plate (related to
BulbStart or BackBulbStart) and positive if the point de�nes a transition on the right side
of the bulb plate (related to BulbEnd or BackBulbEnd).
Lateral weld intermediate points
The intermediate points needed to avoid the collision of the torch with lateral plates during
the transition from one lateral weld to the next one can be related to the end point of the
outer lateral welds.
(a) Left view (b) Top view
Figure 5.12: Left and top views of a bulb plate with the intermediate points displayed
This relation consists of a translation on the Y and Z axes. To ensure the correct relocation
of these points last bulb plate's height (Bh8)is used:
Xbulbinter
YbulbinterZbulbinter
=
Xbulb
YbulbZbulb
+
0
Bh81, 5 ·Bh8
(5.7)
Bulb plate transition intermediate points
One �nal group of intermediate points is de�ned to ensure a good transition between bulb
plates. Once the welding of one plate has been carried out the tool has to move to the
next one without colliding with any of the bulb plate or the lateral plate. To ensure this
the following points are de�ned:
42
5.3. Welding parameters de�nition Aalborg University
Figure 5.13: Bulb plate transition intermediate point
This intermediate points' coordinates are related to the back bulb weld points in a similar
way to the transition points between the front and back welding of the plate. The
translation is de�ne by the same equation, but the Z translation is smaller because there
is no need to avoid any bulb plate from above.
Xinterbulb
YinterbulbZinterbulb
=
Xbulb
YbulbZbulb
+
Bhi±Bh∗i
LateralHeight
∗ +Right,−Left (5.8)
5.3 Welding parameters de�nition
Once described the structure of the robot program, there are a set of parameters that have
to be de�ned or calculated for every weld that the robot has to carry out to produce the
selected lid model:
� Welding speed
� Welding voltage
� Welding material feed speed
� Welding angles and tool orientation
The determination of these parameters is not an straight forward process and depend
on an important number of variables. However, one of the variables that most in�uences
these parameters (except the welding angle) is the thickness of the plate that is going to be
welded. So, as a simpli�cation, in the following points the relation between the parameters
and the plate thickness will be set. (See Appendix B)
43
VT3 5. Automatic welding process
Table 5.1: Welding parameters for di�erent plate thicknesses, [CSFE, 2006]
Plate thickness Voltage Wire feed Travel speed
[mm] [V] [mm/s] [mm/s]
7 20 45 8
8 22 45 8
9 24 50 7
10 26 50 7
11 24 60 7
11.5 26 65 7
12 24 75 6
13 26 85 6
14 28 90 6
All the welds that are carried out to manufacture a lid plate consist of joining 90◦ �llets.
The main angles that form the tool and the working piece in this kind of welding are shown
in �gure 5.14:
Figure 5.14: Main welding angles, Source: WeldCorTM
Work angle: Is the angle of less than 90◦ between a line perpendicular to the major
work piece surface and the plane determined by the electrode axis and the weld axis.
Typically this angle is set to 45◦, but any possible collision has to be avoided
Travel angles: Push and Drag angles are the maximum angles that the tool forms
when it travels through the welding path with respect to the perpendicular position
of the tool to the welding path.
The determination of the tool orientation depends on which type of weld is being carry
out, so it will be analyse with more detail on the next section.
44
5.4. Tool orientation de�nition Aalborg University
5.4 Tool orientation de�nition
Once the welding points coordinates have been correctly de�ne the tool orientation for each
one of the points has to be set. This is critical point on the robot movement de�nition
to ensure the avoidance of collisions and the optimal welding process for a given set of
parameters.
Figure 5.15: Tool orientation during right lateral plate welding
For this purpose, a complex Robot Path Planning algorithm has to be implemented. This
process consist of breaking down the desired movement task into discrete motions that
satisfy movement constraints and makes possible to optimize some aspect of the movement;
tool orientation in this case. However, this task is beyond the scope of this project and
would be an interesting future work to optimize this solution.
In this project, the de�nition of the tool orientation has been set manually, checking
orientations that ensure no collisions or singular points and are close to the desired welding
angles. Next table shows the tool orientations chosen for every weld point type:
Table 5.2: Possible tool orientation
Weld pointTool orientation [ ◦ ]
Roll ( φ ) Pitch ( θ ) Yaw ( ψ )
Right Lateral 20 -30 -90
Left Lateral 15 45 -90
Bulb Start 18 -20 -90
Bulb End 0 60 -120
Left Bulb Lateral 20 -40 -93
Right Bulb Lateral 0 60 -120
Back Bulb Start -45 0 -90
Back Bulb End -10 60 -80
Back Left Bulb Lateral -45 0 -90
Back Right Bulb Lateral -10 60 -80
45
VT3 5. Automatic welding process
Knowing all the angles all the rotation matrices can be built following the next structure
obtained from multiplying the three rotation matrices of each turn in Yaw - Pitch - Roll
order:
RT = RTψ ·RTθ ·RTφ =
c(ψ)c(θ) s(φ)s(θ)c(ψ)− c(φ)s(ψ) s(φ)s(ψ) + c(φ)s(θ)c(ψ)
c(θ)s(ψ) c(φ)c(ψ) + s(φ)s(θ)s(ψ) c(φ)s(θ)s(ψ)− s(φ)c(ψ)−s(θ) s(φ)c(θ) c(φ)c(θ)
For an easier manipulation of the rotation matrix of each orientation and because of
RobotStudio requirements, the corresponding quaternion would be used to represent all
the orientations. The structure of the rotation matrix can be de�ned the following way:
RT =
x1 y1 z1x2 y2 z2x3 y3 z3
(5.9)
The components of the quaternions can be calculated from this rotation matrix using the
following expressions:
q1 =
√x1 + y2 + z3 + 1
2
q2 =
√x1 − y2 − z3 + 1
2sign(q2) = sign(y3 − z2)
q3 =
√y2 − x1 − z3 + 1
2sign(q3) = sign(z1 − x3)
q4 =
√z3 − x1 − y2 + 1
2sign(q4) = sign(x2 − y1)
So, the value of the quaternion for each tool orientation is displayed on the next table:
Table 5.3: Quaternion of every possible tool orientation
Weld pointQuaternion
q1 q2 q3 q4
Right Lateral 0,707106 0 -0,241844 -0,664463
Left Lateral 0,612372 0,353553 0,183013 -0,683013
Bulb Start 0,706999 -0,012341 -0,230211 -0,668583
Bulb End 0,433013 0,433013 0,25 -0,75
Left Bulb Lateral 0,680096 -0,132001 -0,350218 -0,630391
Right Bulb Lateral 0,433013 0,433013 0,25 -0,75
Back Bulb Start 0,653281 -0,270598 0,270598 -0,653281
Back Bulb End 0,688901 0,262350 0,430082 -0,521169
Back Left Bulb Lateral 0,653281 -0,653281 0,270598 -0,270598
Back Right Bulb Lateral 0,688901 -0,521169 0,430082 0,262350
46
5.5. Welding sequence de�nition Aalborg University
5.5 Welding sequence de�nition
Once all the welding coordinates and paths have been de�ned the welding sequence has
to be set. Taking into account the disposition of the lid plate in the working area, the
closest weld to the Home position of the mechanism is the right lateral - main plate and
consequently the �rst weld to be carried out. After this �rst weld, the welds between bulb
plates and main and lateral plates would be carried out, starting from the most inner bulb
plate as is described in �gure 5.16:
Figure 5.16: Welding path representation in RobotStudio
5.5.1 Number of passes de�nition
Depending on the thickness of the plates that have to be welded one or more passes would
be necessary to ensure that all the required welding material is correctly deposited. To
determine the number of passes needed for every bulb plate thickness the data from table
5.4 has to be taken into account.
First the weld cross section area (Aw) has to be de�ned to determine how much welding
material is needed for every type of weld. To calculate this area the weld throat has to be
de�ned. In this case, all the welds consist of "T" shape �llet welds like the one shown in
�gure 5.17:
Figure 5.17: Fillet welds, Source: mitcalc.com
The �llet weld thickness (a) is chosen depending on the used material and thickness of the
welded parts. As a recommendation, the following expression can be followed to determine
47
VT3 5. Automatic welding process
the weld thickness:
amin ≥ tmin (5.10)
Knowing this and considering a welding angle of 45 the weld throat area can be calculated
as:
Aw = a2 = t2min (5.11)
With the required welding material cross area and the density of the welding material
(typically 7850 kg/m3) the target mass that has to deposited per meter of welding can
be calculated. After that, considering a deposit rate of 8 kg/h for an automatic GMAW
(see deposition rate table 2.1) and the speed of every type of welding the mass of welding
material that the robot is able to deposit is determined. Then, just by dividing these two
values the required number of passes is obtained. The following table show all these values
for the di�erent plate thicknesses:
Table 5.4: Welding passes calculation
Plate Travel Target Deposited
thickness speed Aw mass mass Passes
[mm] [mm/s] [mm2] [kg/m] [kg/m]
7 8 4.9 0.31 0.28 1
8 8 6.4 0.5 0.28 2
9 7 8.1 0.64 0.31 3
10 7 10 0.79 0.31 3
11 7 12.1 0.95 0.31 3
11.5 7 13.2 1.03 0.31 3
12 6 14.4 1.13 0.37 3
13 6 16.9 1.32 0.37 4
14 6 19.6 1.54 0.37 4
5.5.2 Outer lateral plate welding sequence
The lateral plates of all the lid plate models studied in this project have a thickness of 10
mm, so based on table 5.4, three passes are needed to properly weld them to the main
plate. Taking this into account, the same sequence can be de�ned for the outer welding of
the lateral plates of all the lid plate models.This sequence is represented in the following
�gure:
48
5.5. Welding sequence de�nition Aalborg University
Figure 5.18: Outer lateral plate welding sequence
1. Start on the LateralStartInter point of the right lateral plate and move to Lateral-
Start to start the welding.
2. Carry out three welding passes, ending at LateralEnd of the right plate.
3. Follow the transition sequence using the LateralEndInter points of the lateral plates
described on section 5.2.2 to reach LateralEnd point of the left lateral plate and start
the second welding.
4. Carry out three welding passes, ending at LateralStart of the left plate and move to
the LateralStartInter point to �nish with the outer weld of the lateral plates.
5.5.3 Bulb plate and inner lateral plate welding sequence
All the bulb welding sequences start with the front welds. The thickness of the bulb plate
determines the number of passes that are needed. Each one of these passes will follow a
left to right or a right to left sequence like the ones described bellow:
Left to Right Sequence
� LeftBulbLat� BulbStart� BulbEnd� RightBulbLat
Right to Left Sequence
� RightBulbLat� BulbEnd� BulbStart� LeftBulbLat
These two sequences alternate until the required number of passes are ful�lled. Once the
front welds have been �nished the transition to the back side of the plate is carried out.
This transition is de�ned by the intermediate points determined in section 5.2.2 and will
situate the robot at the beginning of one of the back bulb - lateral plate welds.
Once the robot is situated on the back side of the bulb plate, both the back bulb weld and
the inner lateral weld segment are carried out. Under this lines an example of this welding
sequence is described:
49
VT3 5. Automatic welding process
Figure 5.19: Bulb plate and inner lateral plate welding sequence
1. After the transition to the back side of the bulb plate the robot will be situated on
the beginning of the back bulb - lateral weld (BackLeftBulbLat in this case).
2. First, the bulb left bulb - lateral weld is carried out, with the robot ending at the
BackBulbStart point.
3. Then, all the passes needed for the left inner lateral weld segment are carried out.
This segment is de�ned by the BackBulbStart point of the �rst bulb plate and the
BulbStart point of the second one.
4. The last operation will end at the BulbStart point of the second plate, so to ensure
a correct return transition to the �rst one, the robot will move through the LeftIn-
terBulb point to reach the BackBulbStart point of the �rst bulb plate.
5. After that, the �rst pass of the remaining bulb and bulb - lateral welds are carried
out, �nishing at the BackRightBulbLat point.
6. At this point, the same sequence followed for the left inner lateral segment weld is
followed.
7. Finally, the remaining passes of the bulb and bulb - lateral welds are carried out to
�nish the welding of the bulb plate.
50
Lid Plate Generator 6The parametrization of the lid plate design and the interaction with the 3D model to
obtain all the manufacturing data is possible thanks to a SolidWorks add-in that has
been called Lid Plate Generator. The development of this add-in starts from SolidDNA,
a SolidWorks API that makes the programming of add-ins easier and intuitive developed
by Luke Malpass.
The Lid Plate Generator is able of scaling a 3D base model of the lid plate based on what
was stated in chapter 4 and then generate a RAPID robot program with the information
obtained from the model that has to be loaded to RobotStudio to simulate the welding
process of the di�erent lid pate models presented in this project.
Figure 6.1: Lid Plate Generator task pane
51
VT3 6. Lid Plate Generator
6.1 Parametric modelling
Remembering all that was said at the conclusion of chapter 4; once the base model has
been de�ned with all the equations and relations with the Custom Properties stated, the
user only has to correctly set the values of those properties to generate a valid 3D model of
any of the available lid plate models. So, from the parametric modelling point of view, the
main objective of the Lid Plate Generator is to ease the modi�cation of those properties
by the user to generate valid lid plate models. For this purpose, �rst a task pane has been
created that follows the next logic:
Figure 6.2: Task pane logic
Following the �ow diagram of �gure 6.2, the �rst that the user has to do to access the full
functionality of the add-in is to select a valid base model like the one described before.
Until the user does this action, the task pane of the add-in will show the display shown in
�gure 6.3a and once a valid model has been uploaded to SolidWorks, the displayed task
pane will be the one shown in 6.3b.
(a) Start view of the task pane (b) Fully operative task pane
Figure 6.3: Add-in task pane's views
52
6.1. Parametric modelling Aalborg University
As it can be seen on the task pane shown in �gure 6.3b, the user has to choose the lid plate
design that wants to generate from all the available models that are listed on the combo
box. Once the desired model has been selected, all the text boxes below are �lled with the
geometrical information of the selected lid plate design. Then, as the �ow diagram shown
in �gure 6.2, each of the buttons in �gure 6.3b enable one of the three options that the
user has:
1. Generate: This button enables the introduction of changes on the base model.
Once it is clicked, all the values shown in the text boxes will be translated to the
base model scaling and modifying it to obtain the 3D model.
2. Reset: By clicking this button the values of the driving parameters are set to the
ones of the base model.
3. Save: The user can save the desired 3D model of the lid plate by clicking this button.
It is interesting to analyse in detail the logic that the add-in follows when the Generate
button is clicked. The following �ow diagram shows clearly this logic:
Figure 6.4: Generate logic �ow diagram
So, following the �ow diagram in �gure 6.4, the �rst thing that the add-in does is to get the
lid plate model selected by the user from the combo box. After that, the lid plate model is
used to determine the value of Custom Properties that do not need further information (as
the inner and outer diameters) and the set of bulb plates that has to be installed for that
particular model from the Excel data base. With this new information the last parameters
are de�ne, such as the ones that de�ne the linear relation of the disposition of the lid
plates. Finally, all the custom properties are set and the model is rebuild to generate the
desired lid plate design.
When the user has generated the desired 3D model for a certain application all the
dimensions of the components of the lid plate would have been de�ned too. With the 3D
53
VT3 6. Lid Plate Generator
model of the desired lid plate fully de�ne, it can be used to obtain very valuable information
to de�ne the welding robot program that would carry out all the welds required. So, the
add-in is extended to be able to interact with the SolidWorks 3D model.
6.2 Interaction with the lid plate 3D model
The �rst problem that arises while de�ning the welding process of the lid plate is the
de�nition of the welding paths. To be able to overcome this problem, another functionality
has been added to the SolidWorks add-in described on the previous section. If all the
welding paths are de�ned on the base model, they would be rede�ned and adjusted to the
scaled model of the lid plate, thanks to the parametric design of the lid plate.
Consequently, all the welding paths stated previously are de�ned on the base model of the
lid plate using a sketch. This sketch is formed by lines that match the joints between the
di�erent plates that form the lid plate. As the start and the end points of these lines are
referenced to points belonging to the plates, when these components are scaled, all the
lines will change its size and coordinates too.
Figure 6.5: Lid plate base model with the welding paths de�ned in blue
Once all the lines needed to de�ne the welding paths are drawn, a new button is added
to the SolidWorks add-in to enable the creation of a report in which all the coordinates of
the weld lines' start and end points are shown. To do this, the user has to select the Edit
Sketch option to access the lines that de�ne the welding paths and select all the lines from
which the coordinates of the start and end points are desired to get.
The next step is simply to press the Get button next to Sketch coordinates in the task
pane to make the add-in produce the desired report and save it in whatever �le the user
chooses. This report would contain all the coordinates needed to de�ne the welding paths
to manufacture the chosen lid plate design.
54
6.2. Interaction with the lid plate 3D model Aalborg University
Figure 6.6: Get button to obtain the sketch coordinates in the task pane
An example of a report generated from a scaled model cab be seen bellow these lines:
Lateral plate weld 1
Start point: 2005.20581632308 623.417453471473 15
End point: 5671.15956207984 1957.71549712362 15
...
Left Bulb Lateral plate weld 1
2900 933.133235537259 100
Bulb plate weld 1
Start point: 2900 933.133235537259 15
End point: 2900 -933.133235537259 15
Right Bulb Lateral plate weld 1
2900 -933.133235537259 100
...
It is important to remember that all these coordinates are referred to and origin placed
on the center of the inner diameter of the lid plate. Furthermore, looking at �gure 6.5 it
can be realized that only the front welds of the bulb plates are represented in the sketch.
So, all the relations described in sections 5.1.2 and 5.3 have to be applied to obtain all the
points required for the de�nition of the welding process.
55
VT3 6. Lid Plate Generator
6.3 RAPID program generation
Remembering what was set on the project goals (chapter 3):
"With all the data from the previous steps, a robot programming will be carried out in order
to make the manufacturing process completely automatic. This programming will be
automatically generated and uploaded to ABB's o�-line simulation and programming
software; RobotStudio.[...]"
To ful�l this objective, the Lid Plate Generator analyses all the data generated from the
interaction with the parametrized lid plate model and all the characteristics of the welding
process de�ned in chapter 5 to be able to automatically generate a welding robot program.
Once the desired lid plate 3D model has been generated and saved, the user has to click
the Generate RAPID program button from the add-in's task pane. By doing this the
add-in will generate all the documents required by RobotStudio to de�ne a welding robot
program and will ask the user the location to save them.
The Lid Plate Generator generates all the �les, con�gurations and instructions following
the structures speci�ed by RobotStudio. For further information about all this features see
Appendix C.
6.3.1 Weld data de�nition
The �rst thing that the Lid Plate Generator does during the robot program generation is
the de�nition of the seam and weld data following the structure stated in section C.1 of
Appendix C. To do this, it follows the next logic:
Figure 6.7: Weld data de�nition logic
A weld data has to be created for every di�erent plate thickness that has to be welded.
So, the add-in checks the di�erent thicknesses that are present on the selected lid plate
model and the collects all the parameters for each case from the Bulb Plate database to
write them in the RAPID �les.
6.3.2 Robot target generation
The next step that the add-in takes after de�ning the weld data is to generate robot targets
from the sketch lines de�ned on the lid plate model. For each selected line it follows the
next �ow diagram:
56
6.3. RAPID program generation Aalborg University
Figure 6.8: Target line generation logic
First, it checks if the selected line represents a bulb or a lateral weld. If the X coordinate of
the start point is equal to the X coordinate of the end point it will mean that the selected
line is a bulb weld. In the case of the bulb welds, the add-in de�nes both front and back
welds applying the relations described in section 5.2. Additionally, all the intermediate
points related to each weld are de�ned.
Once all the points coordinates have been obtained from the sketch line they are translated
to the welding cell reference system applying the translation described in section 5.1.2.
Then all the additional data required by RobotStudio to complete a robot target is
generated:
� Tool orientation
� Robot con�guration
� External axes position
On the one hand, the tool orientation depends on the type of point and is obtained on the
57
VT3 6. Lid Plate Generator
consultation of the database by stating the quartenion that de�nes the rotation of the tool
with respect to the origin frame. All the quartenions can be found in table 5.3.
On the other hand, RobotStudio allows to Autocon�gure any path de�ned to the
con�guration that best suits the robot. So, for every welding point the robot con�guration
is set to [-1,0,-1,0], taking into account that once the welding path has been Autocon�gured
they might change to a more suitable con�gurations.
Finally, for the robot to be able to reach all the welding points the position of the XY
crane has to be de�ned for each target. To ensure a good reachability to all points and
to maintain the robot far from critical con�gurations, the position of the two axes of the
crane are calculated following the next expression:
[Xcrane
Ycrane
]=
[Xpoint
Ypoint
]·
[−1 0
0 1
]+
[0
−1000
](6.1)
It is important to take into account that due to the disposition of the coordinates axes of
the station, all the X coordinates of the welding points will have a negative value. However,
the position of the crane axes needs to have a positive value.That is the reason why the
position of the X axes for every point of the crane is obtain by changing the sign of the
point's X coordinate.
6.3.3 Move instruction and sequence generation
RobotStudio provides four di�erent instructions to de�ne the di�erent movements between
targets that �t this welding application (for a more detailed description go to Appendix
C):
� MoveL: de�nes a normal movement between two targets.
� ArcLStart: de�nes a movement to a target where the welding torch is going turn on.
� ArcL: de�nes the movement between intermediate welding targets maintaining the
welding torch on.
� ArcLEnd: de�nes the movement to a target where the welding torch is going to
turn o�.
The de�nition of each instruction is related with the type of target towards which the
robot has to move (see section 5.2.2) and the sequence needed to perform each weld (see
section 5.5). This de�nition is done after the determination of all the robot targets and
follows the next logic:
58
6.4. Welding characteristics Aalborg University
Figure 6.9: Movement instruction generation logic
Following the �ow diagram from �gure 6.9, when the add-in �nishes generating all the
robot targets, it reads again the sketch and checks every sketch line to see what type of
weld it represents.
Once the type of weld is determined, the thickness of the plate that is going to be welded
is obtained. This value will determine the number of passes and the parameters of the
instructions, like the welding voltage or the speed. All this data is required to determine
the sequence of targets that the welding robot has to follow to ful�l that weld. Finally,
this sequence is programmed by the correct sort of the moving and welding instructions
de�ned before to build the robot program.
6.4 Welding characteristics
The last functionality added to the Lid Plate Generator is the determination of the total
welding length and welding material volume needed to produce the desired lid plate model.
This data is fundamental to carry out the economic study of each model of lid plate because
it a�ects directly the welding time and the welding material cost.
To obtain the length and volume, the following logic is followed:
59
VT3 6. Lid Plate Generator
Figure 6.10: Welding characteristics obtaining logic
The user can select as many sketch lines as wanted to de�ne the welding length and volume
to be calculated. The add-in reads all the lines and determines what kind of weld they
represent. Knowing this, the plate thickness and weld length are obtained. With this
values the volume of welding material can be obtained following the expression described
in section 5.5.
60
Economic study 7To determine the bene�ts of the automation of the lid plate manufacturing process an
economic study has to be carried out. Here the productivity and e�ciency improvements
will be analyse to see if is worth it to make all the investment on the automatic welding
station. Additionally, the in�uence of design variation on the manufacturing cost will be
analysed. How the welding cost varies in di�erent lid plate solutions for a same applications.
7.1 Automatic welding cost
To compare the automatic solution proposed in this project and the traditional welding
method used until now all the costs will be analysed.
7.1.1 Welding time calculation
To determine the welding time needed to manufacture the lid plate the �rst thing to do is
to determine the amount of material needed to carry out all the welds. The total volume
of welding material (V ) is calculated by multiplying the length of each weld (L) times its
weld throat area (Aw) as is shown in equation 7.1:
V = L ·Aw (7.1)
To calculate the weld throat area the weld cross section has to be de�ned. This parameter
is obtained using the same expression stated on the previous section for "T" shape �llet
welds with a determine thickness (a) like the one shown in �gure 5.17.
So, knowing the volume of welding material it is possible to calculate the mass of material
required for the welding process (Md) by multiplying the volume times the density of the
welding material (ρ):
Md = V · ρ (7.2)
However, the consumption of welding material would be bigger due to di�erent material
losses during the welding process. The real welding material mass (Mw) is calculated
correcting the previous value:
Mw =Md · 1.8 (7.3)
Knowing the required mass, to calculate the time needed to deposit all the welding material
(tarc) can calculated by the expression given in equation 7.4:
tarc =Mw
dr(7.4)
61
VT3 7. Economic study
The deposit rate (dr) can be obtained from table 2.1 from section 2.3. Taking into
account that the welding technology used for the manufacturing of lid plates is Gas Metal
Arc Welding (GMAW), for the cost calculation the deposit rate would be considered to be
8 kg/h.
Finally, to calculate the real time needed to produce each lid plate the e�ciency of the
welder has to be added to the previous time value. The e�ciency of each welding method
is stated in table 7.1:
Table 7.1: Welding e�ciency for di�erent welding methods [León, 2013]
Welding method Welder e�ciency, φ [%]
Manual 5 - 30
Semiautomatic 10 - 60
Automatic 50 - 95
So, the total welding time is obtained by the expression 7.5:
tt =tarcφ
(7.5)
7.1.2 Labour cost
Labour cost can be easily obtain by multiplying the total welding time (tt) by the cost per
hour of a welder:
CL = tarc ·Chφ
(7.6)
As it can be seen in equation 7.6, this value of the labor cost strongly depends on the
welding method used in the manufacturing process.
7.1.3 Electrode cost
To calculate the electrode cost the number of electrodes consumed during all the welding
process has to be determined. This value is obtained by multiplying the price of each
kilogram of electrode (Cel) times the total mass of welding material used (Md). However,
this value has to be modi�ed by the deposition e�ciency factor (ψ):
CEl =Md ·Celψ
(7.7)
Deposition e�ciency depends mainly on the welding technology that is being used. Table
7.2 shows the typical values of ψ for the most common welding technologies:
Table 7.2: Deposition e�ciency factor for di�erent welding methods [León, 2013]
Welding technology Deposition e�ciency factor, ψ [%]
SAW 95 - 100
GMAW 90 - 95
FCAW 80 -85
62
7.1. Automatic welding cost Aalborg University
7.1.4 Energy cost
The energy cost of the welding process is calculated by multiplying the system's power
consumption (P) times the time that the torch is welding (tarc) and the cost of energy (cE)
in ¿/KWh. Additionally, the e�ciency of the welding technology has to be applied to the
expression by the means of the deposition e�ciency.
CE = P · tarc ·cEφ
(7.8)
7.1.5 Total cost comparison
To be able to compare the traditional welding process and the designed automatic solution
all the cost's items and the productivity have to be calculated. To obtain the total cost of
the welding process all the cost items described on the previous points have to be added:
CT = CL + CE + CEl (7.9)
As an example, the cost of the manufacturing of the lid plate base model will be studied.
For both welding techniques there is a set of process parameters that have to be de�ned:
Table 7.3: Process parameters
Parameter Value
Torch Power 6.6 KW
dr 10 kg/h
ψ 90 %
The weld cross section is the same, just like the total welding length. With these values
the total welding material mass and the arc time can be determined. Additionally, the
unitary costs of every cost item have to be de�ned. The values of these parameters are
shown in table 7.4:
Table 7.4: Welding geometry
Parameter Value
L 40,0339 m
V 0,0026 m3
Mw 20,44 kg
tarc 4,6 h/lidplate
Ch 50 ¿/h
Cel 1,2 ¿/kg
ce 0,14 ¿/KWh
With all this data the cost breakdown can be calculated for each welding technique. The
results are shown in table 7.5:
63
VT3 7. Economic study
Table 7.5: Welding time and cost comparison
Manual welding Automatic welding
φ 30% 65%
Welding time 15,33 h 7,08 h
Labor cost, CL 766,5 353,8
Electrode cost, CEl 53,75 53,75
Energy cost, CE 14 6,5
Total cost, CT 834,25¿ 414,05¿
As can be seen in table 7.5, the great di�erence of e�ciency between the automatic and
the manual is the responsible of the drastic reduction on the welding time when the robotic
solution is used. This fact a�ect directly the labour cost, which is the most important cost
item.
The main conclusion that can be taken from this economic comparison is that the
important reduction on the welding cost of the lid plate makes the automatic solution
presented in this project a very interesting action to carry out in order to reduce the overall
cost of the Mono Bucket and consequently the LCOE of the O�shore Wind technology.
7.2 Cost - design variability
Once shown the improvement on the welding process cost, it is interesting to see how the
cost changes depending on which model is manufactured. As it was said in chapter 4, for
every application there are di�erent available models of the Mono Bucket that can ful�l
the mechanical requirements and be possible options. That is why it is interesting to see
which is the best choice from the welding cost point of view.
To carry out this comparison the same procedure described in section 7.1 will be followed
for every available lid plate model. The all the costs breakdowns and times calculated are
displayed on table D.1 on Appendix D.
7.2.1 Cost variation with pressure
First the variation of the cost with the pressure that the complete lid has to withstand
is studied. As this pressure increases, for a same Mono Bucket, mechanical stresses that
each bulb plate has to withstand would increase. So, for higher pressure applications, the
thickness and height of the bulb plates arrange on top of the main plate would increase.
This increase in the thickness of the plates would mean that the amount of welding material
needed to ensure a correct welding would increase too. Consequently, the time required
to ful�l all the welding process would increase to, so would do the labour, electrode and
energy costs. This phenomenon can be seen in the graphs shown in �gure 7.1:
64
7.2. Cost - design variability Aalborg University
Figure 7.1: Cost variation with lid pressure
In the graphs of �gure 7.1 it can be seen that the increase of the total welding cost is not the
same for the di�erent diameters of the Mono Bucket. This is mainly due to the bulb plate
selection that the FastBertha does for every model. The limited bulb thicknesses available
means that some times the picked bulb plate model is thicker than what is required, so
the weld needed to join that plate would be bigger than needed. This di�erence on the
bulb plate thicknesses can be seen in table 4.3.
This is specially signi�cant for the 10 meter diameter Bucket. The 300 KPa and 400
Kpa model's welding cost is very similar because, even if the bulb plates are higher, the
thicknesses are maintained quite similar.
65
VT3 7. Economic study
7.2.2 Cost variation with lid angle
On the other hand, it is interesting to analyse what lid angle makes cheaper to produce
a hole Mono Bucket lid. Although the welding cost to produce a lid plate model with a
wider angle would be bigger, the number of lid plates needed to complete the entire lid of
the Mono Bucket would decrease. For this reason, instead of analysing the welding cost
per lid plate, the cost of the entire lid would be analysed to carry out a proper comparison
and determine the cheaper solution from the welding cost point of view.
From all the available models obtained with Universal Foundation's tool, only 10 and 12
meter diameter models have di�erent lid angle models, always for lid pressure of 400 KPa.
So, only for these two cases the cost variation with the lid angle will be carried out.
Figure 7.2: Cost variation with lid angle (Do = 10 m)
For the case of a Mono Bucket with a diameter of 10 meters, it can be seen in �gure 7.2
that the best solution from the welding cost point of view is to make use of a lid plate
design with an angle of 12◦, what means that 15 lid plates would be needed to complete
the lid of the Bucket.
Another interesting fact that can be seen in �gure 7.2 is that a lid compose by 20◦ lid plate
models is cheaper to weld than one form by plates of 15◦. These happens because, even if
it is cheaper to produce a single 15◦ plate than a 20◦ one, the prize is not low enough to
produce a complete lid of 12 lid plates of 15◦ rather than one with 8 of 20◦.
66
7.3. Cost variation with diameter Aalborg University
Figure 7.3: Cost variation with lid angle (Do = 12 m)
As for the 10 meter Mono Bucket, the cheapest model to weld for the 12 meter one is the
one of 12◦. However, the di�erence between this model and the one of 15◦ is very small, so
other aspects from the total cost (like the material cost or the transportation) can easily
incline the weighing on the behalf of the 15◦ lid plate.
It is important to underline what was said in the previous section concerning the in�uence
of the available bulb plates. As the lid angle increases, the number of lid plates needed to
install would be reduced but the stresses that they would have to undertake would increase
too. This means that the bulb plates to be installed would be thicker and more costly to
weld. If the chosen bulb plates' thickness is bigger that the requirement, the cost would
increase even more. This is mainly the reason why the lid plate models with wider lid
angles are more expensive to weld.
7.3 Cost variation with diameter
Finally, the cost variation with the Mono Bucket diameter is analysed for di�erent
operating lid pressures. In this case, the available models only have been designed for
three di�erent lid pressures (200, 300 and 400 KPa) which represent di�erent working
environments where the Mono Bucket can be installed.
67
VT3 7. Economic study
Figure 7.4: Cost variation with diameter
As it can be seen in the graphs of �gure 7.4, for all possible lid pressure the best option to
reduce the welding cost is to manufacture the lid of the Mono Bucket with the lid plates
of the smallest diameter possible. The longer welding distances and thicker bulb plates
make the bigger diameter lid plate models to be more expensive.
68
Conclusion andperspectives 8
8.1 Conclusion
In conclusion, the main achievements of this project are:
� Development of a parametric design of a set of lid plate models.
� De�nition of an automatic welding process for lid plates based on a robot arm
mounted on a gantry crane.
� Development of an Add-in for a fast parametrization of lid plate models and RAPID
robot program generation for an automatic welding process.
� Proof of the economic bene�ts of using an automatic welding process to produce the
parametrized set of lid plate models.
The parametrization of the design makes it much faster and easier to develop 3D designs
of the di�erent lid plate models available for this project. What is more thanks to the
easy resizing of the base model the sketches that de�ne the weld paths are simultaneously
correctly resized as weld. This fact is key to automatically generate the robot program no
matter the lid plate design wanted to be manufacture.
Checking the project goals stated at the beginning of the project:
X Design of a 3D parametric model of the lid plate
Development of an automatic manufacturing data generation tool
X Automatic welding coordinates de�nition.
X Automatic welding sequence de�nition.
Automatic welding parameters de�nition
X Average welding parameters de�nition.
X Optimization of the welding parameters
X De�nition of an automatic manufacturing process based on a robotic arm
69
VT3 8. Conclusion and perspectives
The only sub-objective that has not be tackled in this project is the optimization of the
welding parameters such as the welding speed or voltage. These parameters have been
set to average values for this kind of welding processes to be able to generate the robot
program and simulate it even if it is not the most optimal one.
This project has proved that an automatic welding process is a recommendable way of
reducing the manufacturing cost of the lid plates. So, it can be concluded that this is a
very interesting solution to reduce the LCOE of O�shore Wind Energy by reducing the
cost of the foundation.
In conclusion, this project o�ers a very interesting tool to easily work in the design of
di�erent lid plate models and automatically obtain the welding robot program to simulate
and posteriorly weld the desired lid plate model. However, there is further work and
optimization that would be needed to carry out before implementing this design and
manufacturing solution on a real application.
8.2 Further work
Even if the Lid Plate Generator is a fully functional tool, it needs some optimization to
be able to use it to de�ne real welding processes of lid plates. This optimization should be
centred specially on a more detailed de�nition of welding parameters and an enlargement
of the set of available lid plate models.
As it was commented on chapter 5, a Robot Path Planning algorithm has to be
implemented to optimize the tool orientation. This is a critical fact to ensure that no
collisions happen during the welding process of the lid plate, while the robot maintains
the best orientation from the welding characteristics point of view. This, will strongly
in�uence the other welding parameters, so it should be the �rst thing to do to improve
this solution.
What is more, a better and more detailed analysis of the welding parameters have to be
carried out. On the one hand, it is interesting to analyse how the continuous orientation
change of the welding torch a�ect the quality of the welds to see if this parameter has
to be rede�ned. On the other hand, a proper tuning of the welding parameters, such as
voltage, feed rate and speed, is very necessary to ensure that the quality of the welds. For
this purpose some welding tests would be necessary with plates of the sections present on
the di�erent lid plate models and the same welding equipment to be installed on the �nal
application.
Additionally, the available lid plate model data base should be extended to be able to use
this solution for a wider set of Mono Bucket designs. It would be specially interesting
to carry out the parametric design of lid plates with a number of bulb plates di�erent
from 8. This plates have proved to be a very determining factor of the welding time and,
consequently, of the welding cost of every lid plate model. So, after developing a parametric
design for this lid plates models a new economic study should be carried out to see the
in�uence of the number of bulb plates on the cost breakdown.
70
List of Figures
1.1 Wind power in Denmark [Neslen, 2016] . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Annual o�shore and onshore wind installations (MW) [Europe, 2016] . . . . . . 3
1.3 LCOE for all primary energy sources, Source: Siemens . . . . . . . . . . . . . . 4
1.4 Capital cost breakdowns for typical onshore and o�shore wind systems [IRENA,
2012] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5 Monopile foundation components, Source: 4CO�shore . . . . . . . . . . . . . . 5
1.6 Tripod foundation components, Source: 4CO�shore . . . . . . . . . . . . . . . . 5
1.7 Jacket foundation components, Source: 4CO�shore . . . . . . . . . . . . . . . . 6
1.8 Gravity based foundation components, Source: 4CO�shore . . . . . . . . . . . . 6
1.9 Current o�shore wind foundation type distribution, Source: WEU . . . . . . . 7
1.10 Suction Bucket working principle, Source: Universal Foundation . . . . . . . . 8
1.11 Mono Bucket, Source: LEEDCo . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.12 Lifting of a jacket structure with suction buckets, Source: DONG Energy . . . 9
2.1 Exploded view of a suction bucket [Villumsen, 2017] . . . . . . . . . . . . . . . 11
2.2 Depth variation in the London Array wind farm area, [H. Burningham, 2008] . 12
2.3 Suction Bucket manufacturing process . . . . . . . . . . . . . . . . . . . . . . . 13
2.4 Welding paths types for the manufacturing of the Suction Bucket [Villumsen,
2017] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.5 Estimated cost of a single suction bucket [Villumsen, 2017] . . . . . . . . . . . . 15
3.1 Project �ow diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 FastBertha tool task pane, Source: Universal Foundation . . . . . . . . . . . . 19
4.2 Geometrical parameters of the main plate . . . . . . . . . . . . . . . . . . . . . 21
4.3 Geometrical parameters of the main plate . . . . . . . . . . . . . . . . . . . . . 21
4.4 Lateral plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.5 Bulb plates layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.6 Bulb iron section and main dimensions . . . . . . . . . . . . . . . . . . . . . . . 23
4.7 FastBertha lid plate results example, Source: Universal Foundation . . . . . . . 24
4.8 Geometrical parameters of the lid plate . . . . . . . . . . . . . . . . . . . . . . 26
4.9 Distance between bulb plates relation . . . . . . . . . . . . . . . . . . . . . . . 27
4.10 Distance between bulb plates relation Do = 10 m, α 6= 20◦ . . . . . . . . . . . . 28
4.11 Distance between bulb plates relation Do = 12 m, α 6= 20◦ . . . . . . . . . . . . 29
4.12 Dimensions of a bulb plate section, , Source: British Steel . . . . . . . . . . . . 30
4.13 SolidWorks's Equation Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.1 IRB 4600-40/2.55 working range, Source: ABB . . . . . . . . . . . . . . . . . . 33
5.2 PK 500 welding torch installed on a IRB 4600 robot in RobotStudio . . . . . . . 34
5.3 XY Crane in RobotStudio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.4 Coordinates origins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
71
VT3 List of Figures
5.5 Weld types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.6 Bulb welding points labelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.7 Lateral welding points labelling . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.8 Examples of bulb weld transition intermediate points . . . . . . . . . . . . . . . 39
5.9 Lateral weld transition intermediate points . . . . . . . . . . . . . . . . . . . . 39
5.10 Front and back bulb points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.11 Left and top views of a bulb plate with the intermediate points displayed . . . 41
5.12 Left and top views of a bulb plate with the intermediate points displayed . . . 42
5.13 Bulb plate transition intermediate point . . . . . . . . . . . . . . . . . . . . . . 43
5.14 Main welding angles, Source: WeldCorTM . . . . . . . . . . . . . . . . . . . . . 44
5.15 Tool orientation during right lateral plate welding . . . . . . . . . . . . . . . . . 45
5.16 Welding path representation in RobotStudio . . . . . . . . . . . . . . . . . . . . 47
5.17 Fillet welds, Source: mitcalc.com . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.18 Outer lateral plate welding sequence . . . . . . . . . . . . . . . . . . . . . . . . 49
5.19 Bulb plate and inner lateral plate welding sequence . . . . . . . . . . . . . . . . 50
6.1 Lid Plate Generator task pane . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.2 Task pane logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
6.3 Add-in task pane's views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
6.4 Generate logic �ow diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.5 Lid plate base model with the welding paths de�ned in blue . . . . . . . . . . . 54
6.6 Get button to obtain the sketch coordinates in the task pane . . . . . . . . . . 55
6.7 Weld data de�nition logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
6.8 Target line generation logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
6.9 Movement instruction generation logic . . . . . . . . . . . . . . . . . . . . . . . 59
6.10 Welding characteristics obtaining logic . . . . . . . . . . . . . . . . . . . . . . . 60
7.1 Cost variation with lid pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
7.2 Cost variation with lid angle (Do = 10 m) . . . . . . . . . . . . . . . . . . . . . 66
7.3 Cost variation with lid angle (Do = 12 m) . . . . . . . . . . . . . . . . . . . . . 67
7.4 Cost variation with diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
A.1 Bulb iron section and main dimensions . . . . . . . . . . . . . . . . . . . . . . . 3
B.1 Conditions to apply table B.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
C.1 Example of moving instructions in RAPID, [ABB, 2003] . . . . . . . . . . . . . 9
C.2 Example of a complete welding movement, [ABB, 2003] . . . . . . . . . . . . . 10
E.1 SolidWorksAddinInstaller main window . . . . . . . . . . . . . . . . . . . . . . 16
E.2 Lid Plate Generator start task pane . . . . . . . . . . . . . . . . . . . . . . . . 17
E.3 Lid Plate Generator functional task pane . . . . . . . . . . . . . . . . . . . . . 17
E.4 Description of the functional task pane . . . . . . . . . . . . . . . . . . . . . . . 18
E.5 Edit WeldPaths sketch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
E.6 Set position control panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
E.7 Lid plate model loaded and correctly positioned in the virtual welding station . 21
E.8 Load to Station check box window . . . . . . . . . . . . . . . . . . . . . . . . . 22
72
List of Tables
2.1 Deposit rates of di�erent welding technologies, Source: TWI . . . . . . . . . . . 14
4.1 Lid plate design variations, Source: Universal Foundation . . . . . . . . . . . . 20
4.2 Bulb plates possible disposition [mm], Source: Universal Foundation . . . . . . 24
4.3 Bulb plate sections of every lid plate model [mm x mm], Source: Universal
Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.1 Welding parameters for di�erent plate thicknesses, [CSFE, 2006] . . . . . . . . 44
5.2 Possible tool orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.3 Quaternion of every possible tool orientation . . . . . . . . . . . . . . . . . . . 46
5.4 Welding passes calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
7.1 Welding e�ciency for di�erent welding methods [León, 2013] . . . . . . . . . . 62
7.2 Deposition e�ciency factor for di�erent welding methods [León, 2013] . . . . . 62
7.3 Process parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
7.4 Welding geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
7.5 Welding time and cost comparison . . . . . . . . . . . . . . . . . . . . . . . . . 64
A.1 Bulb plates section description, Source: British Steel . . . . . . . . . . . . . . . 3
A.2 Bulb plates section description, Source: British Steel . . . . . . . . . . . . . . . 4
B.1 Welding procedure schedules for GMAW of plain carbon and low alloy steels
using spray transfer, Source: [CSFE, 2006] . . . . . . . . . . . . . . . . . . . . . 5
D.1 Cost breakdown for all lid plate models . . . . . . . . . . . . . . . . . . . . . . 13
E.1 Lid plate design variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
73
Bibliography
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http://www.4coffshore.com/windfarms/
gravity-based-support-structures-aid8.html, 2013.
4CO�shore, 2013b. 4CO�shore. Jacket or Lattice Structures. Available at
http://www.4coffshore.com/windfarms/jacket-or-lattice-structures-aid5.
html#sthash.XVqjpNtQ.dpuf, 2013.
ABB, 2003. ABB. RobotWare-Arc and ArcSensor, Application Manual, 2003.
Association, 2014. Danish Wind Industry Association. O�shore. Available at
http://www.windpower.org/en/policy/offshore.html, 2014.
Association, 2003a. Danish Wind Industry Association. O�shore Foundations: Mono
Pile. Available at http://dr\T1\omst\T1\orre.dk/wp-content/wind/miller/
windpower%20web/en/tour/rd/monopile.htm, 2003.
Association, 2003b. Danish Wind Industry Association. O�shore Foundations: Tripod.
Available at http://dr\T1\omst\T1\orre.dk/wp-content/wind/miller/windpower%
20web/en/tour/rd/tripod.htm, 2003.
CSFE, 2006. CSFE. Chapter 10, Gas Metal Arc Welding, 2006.
Europe, 2016. Wind Europe. Wind in power - 2016 European statistics. Available at
https://windeurope.org/wp-content/uploads/files/about-wind/statistics/
WindEurope-Annual-Statistics-2016.pdf, 2016.
Gillis, 2014. Justin Gillis. A Tricky Transition From Fossil Fuel. New York Times,
Available at https://www.nytimes.com/2014/11/11/science/earth/
denmark-aims-for-100-percent-renewable-energy.html?_r=0, 2014.
H. Burningham, July 2008. J. French H. Burningham. Historical changes in the
seabed of the greater Thames estuary, The Crown State, July 2008.
ICCS-NTUA, July 2016. ICCS-NTUA. EU Reference Scenario 2016 - Energy,
transport and GHG emissions Trends to 2050, European Commission, July 2016.
IRENA, 2012. IRENA. Renewable energy technologies: cost analysis series. Available
at https://www.irena.org/DocumentDownloads/Publications/RE_Technologies_
Cost_Analysis-WIND_POWER.pdf, 2012.
León, 2013. A. Tejedor De León. Estimación de los costos en la soldadura eléctrica,
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Neslen, 2016. Arthur Neslen. Denmark broke world record for wind power in 2015. The
Guardian, Available at https://www.theguardian.com/environment/2016/jan/18/
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76
Suction Bucket lid plate design and welding automation
Make Offshore wind turbines a competitive technology by making the
production processes of new foundation structures more flexible
By
JAVIER ZARAGÜETA GONZÁLEZ
APPENDIX
Table of content
Appendix A: Bulb plate sections 3
Appendix B: Welding parameters 5
Appendix C: RAPID program structure 7
Appendix D: Lid plate welding time and cost breakdown 13
Appendix E: User guide 15
1
Bulb plate sections A
Figure A.1: Bulb iron section and main dimensions
Table A.1: Bulb plates section description, Source: British Steel
Section description
b t c r
mm mm mm mm
140x8 140 8 19 5
160x7 160 7 22 6
160x8 160 8 22 6
160x9 160 9 22 6
180x8 180 8 25 7
180x9 180 9 25 7
180x10 180 10 25 7
200x9 200 9 28 8
200x10 200 10 28 8
200x11.5 200 11,5 28 8
220x10 220 10 31 9
220x11.5 220 11,5 31 9
3
Table A.2: Bulb plates section description, Source: British Steel
Section description
b t c r
mm mm mm mm
240x10 240 10 34 10
240x11 240 11 34 10
260x10 260 10 37 11
260x12 260 12 37 11
280x11 280 11 40 12
280x12 280 12 40 12
300x11 300 11 43 13
300x12 300 12 43 13
300x13 300 13 43 13
320x12 320 12 46 14
320x13 320 13 46 14
340x12 340 12 49 15
340x14 340 14 49 15
430x17 430 17 62,5 19.5
Welding parameters B
Figure B.1: Conditions to apply table B.1
Table B.1: Welding procedure schedules for GMAW of plain carbon and low alloy steelsusing spray transfer, Source: [CSFE, 2006]
Thickness of Electrode Welding Welding Wire Feed Gas Flow Travel
base metal Diameter Voltage Current Speed Rate Speed
mm mm V A mm/s l/min mm/s
6,4 1,6 24-26 325-375 89-110 21 13-14
6,4 2,4 26-29 400-450 42-51 21 14-15
9,5 1,6 24-26 325-375 42-51 21 8-10
9,5 2,4 26-29 400-450 42-51 21 8-12
12,7 1,6 24-26 325-375 89-110 21 9-11
12,7 2,4 26-29 400-450 42-51 21 11-13
19,1 1,6 24-26 325-375 89-110 21 9-11
19,1 2,4 26-29 400-450 42-51 21 10-12
5
RAPID program structure CThree �les are needed to be able to upload a RAPID program to a station created in
RobotStudio:
RobotProgramm.pgf : This �le indicates the version of the program and the name
of all the �les that are used for the robot programming.
CalibData.mov: This �le contains the calibration data of the tool used by the
robot and the work objects de�ned in the work station.
ModuleX.mov: This �le contains the RAPID program of the robot. There could
be more than one of this �les, but, if so, the name of the extra �les have to be
indicated in RobotProgramm.pgf �le.
Knowing this, the C# program that controls the parametric design of the lid plate and the
welding coordinates report generation is extended to generate this three �les. Basically,
the SolidWorks add-in generates the three �les based on the lid plate model selected by
the user and the welding station and parameters previously de�ned.
The RAPID code from ModuleX.mov is what will de�ne the operation of the welding
station. In every RAPID program four main parts can be distinguish:
a) Welding data de�nition
b) Target coordinates de�nition
c) Robot movement de�nition
d) Movement sequence de�nition
7
C.1 Welding data de�nition
For any welding instruction in RAPID programming language two types of welding data
have to be de�ned:
� Seam data: used to control the start (ignition) and end of the weld.
� Weld data: used to control the welding operation while the arc is established.
In this case the de�nition of the seam data is not relevant and all its components are set
to 0. On the other hand, as weld data usually changes from one weld to another, so it is
important to identify all the di�erent welding conditions and de�ne as many weld data as
needed. To de�ne all the weld data the following structure has to be followed:
PERS welddata name:=[weld_speed, org_weld_speed, main_arc, org_arc];
name : Unique name for each weld data set.
weld_speed : Desired welding speed.
org_weld_speed : Original welding speed.
main_arc: Main arc parameters during the weld phase.
org_arc: Original arc parameters.
For this application, both org_weld_speed and org_arc will be ignored and set to 0 to
simplify the parameter de�nition. On the other hand, weld_speed is represented in mm/s
and parameters inside main_arc data consist mainly on the weld voltage and the welding
material feed speed.
C.2 Target coordinates de�nition
To de�ne each one of the coordinates in the RAPID code, the following structure has to
be follow:
CONST robtarget point_name:=[coord, orient, con�g, external_axis];
point_name : Unique name of the welding coordinate.
coord : X, Y and Z coordinates of the point.
orient : Four values that de�ne the orientation of the tool at the point.
con�g : Four values that de�ne the con�guration of the joints of the robot arm at
the point.
external_axis: Position of each one of the external axes. In total there are �ve
possible values.
C.3 Robot movement de�nition
During the automatic manufacturing process there are two main types of movement that
the robot has to carry out:
� Transition movement
� Welding movement
For each type of movement need di�erent instructions to be de�ned. Figure C.1 show a
simple example of a typical welding robot movement and the RAPID instructions needed
to carry it out:
Figure C.1: Example of moving instructions in RAPID, [ABB, 2003]
Taking this �gure as a reference, transition instructions' structure can be de�ned the
following way:
MoveX point_name, speed, prec, tool ;
X : Represents the type of movement; J for a joint movement or L for a linear move-
ment.
point_name : Name of the point towards the robot is going to move.
speed : Linear speed of the robot during the movement in mm/s.
prec: The precision with which the robot will approach the target point.
tool : Name on of the tool installed on the tip of the robot.
Unlike the transition movements, to de�ne a complete welding movement three di�erent
instructions have to be de�ned.
Figure C.2: Example of a complete welding movement, [ABB, 2003]
As it can be seen in �gure C.2, every welding has to start with a ArcLStart and end with
a ArcLEnd instruction. If the welding consists on one ore more concatenate weld seams
with the same or di�erent welding parameters, as many as needed ArcL instructions have
to be de�ned. These three types of instructions follow the same structure that can be seen
in �gure C.1:
ArcLarc_inst point_name, speed, seam_data, weld_data, prec, tool ;
arc_inst : ArcLStart, ArcLEnd or ArcL.
point_name : Name of the point towards the robot is going to move.
speed : Linear speed of the robot during the movement in mm/s.
seam_data : Seam data of the weld.
weld_data : Welding parameters.
prec: The precision with which the robot will approach the target point.
tool : Name on of the tool installed on the tip of the robot.
C.4 Movement sequence de�nition
Finally, all the movement instructions previously explained are grouped on a certain
sequence to form paths. Two main structures could be distinguish for the movement
sequence de�nition:
Path programs:
These sets of code de�ne a sequence of movement instructions like the one stated in
the previous point.
Main program:
In this program the correct sequence of paths is stated. This is the program that
will run during the simulation of the station.
These two structures could be simpli�ed the following way:
PROC Path name()
Movement instruction 1
...
Movement instruction n
ENDPROC
PROC Process name()
Path 1
...
Path n
ENDPROC
Lid plate welding timeand cost breakdown DTable D.1: Cost breakdown for all lid plate models
Welding Labour Electrode Energy Total
Model time cost cost cost cost
h ¿ ¿ ¿ ¿
MB9_200 7,08 353,8 44,15 6,5 404,48
MB9_300 8,61 430,71 53,75 7,96 492,43
MB9_400 9,55 477,44 59,59 8,82 545,85
MB10_200 9,24 462 57,66 8,53 528,22
MB10_300 10,87 543,51 67,83 10,04 621,39
MB10_400 11 550,1 68,65 10,16 628,92
MB10_400_6 26,1 1304,94 162,86 24,11 1491,91
MB10_400_12 7,97 398,28 49,7 7,36 455,34
MB10_400_15 4,02 201,14 25,1 3,72 229,96
MB11_200 11,14 556,82 69,49 10,29 636,61
MB11_300 11,98 598,83 74,73 11,06 684,64
MB11_400 14,63 731,43 91,28 13,52 836,23
MB12_200 13,47 673,7 84,08 12,45 770,23
MB12_300 15,18 759,17 94,74 14,03 867,94
MB12_400 17,66 882,85 110,18 16,32 1009,34
MB12_400_12 9,30 465,11 58,05 8,6 531,75
MB12_400_15 7,05 352,3 43,97 6,51 402,78
13
User guide EThis document how the SolidWorks' add-in and RobotStudio's welding cell designed for
this project have to be used to obtain the desired results. It is important to remember
that all the following �les are required to ensure the functionality of both tools:
� C# folder: Contains the add-in's code �les and bulb plates Excel data base.
� SolidWorks folder: Contains the lid plate base model on .PRT and .SAT formats.
� RobotStudio folder: Contains the weld station design, 3D models of the crane
components and a �le to save all the RAPID codes generated with the add-in.
The Lid Plate Generator and the welding station have been designed to be installed and
used with SolidWorks 2016 and RobotStudio 6.04, so de compatibility with other versions
of these two software cannot be ensured.
The development of this add-in has been possible thanks to the previous work of the
software developer Luke Malpass from AngelSix. He has created a easy to use SolidWorks
API called SolidDNA, which makes the usage of the SolidWorks API much easier. It is
totally free and open source. For further information about Luke's projects or deeper
questions about the software:
Email: [email protected]
Web page: AngelSix.com
YouTube: AngelSix
15
E.1 Lid Plate Generator
This add-in enables the parametric design of lid plates 3D models to scale a base model
and obtain a desired lid plate design from the set of models available. Once the desired lid
plate model has been generated the welding robot program can be automatically generated
to load it to RobotStudio and simulate the process.
E.1.1 Add-in installation
To install the add-in go into the C# �le and you will �nd the SolidWorksAddinIn-
staller:
Figure E.1: SolidWorksAddinInstaller main window
As it can be seen in �gure E.1, to install the add-in a .dll �le is required. This �le can be
found inside C# �le in the following location:
solidworks-api-master → LidPlate.Generator.AddIn →LidPlate.Generator.AddIn → bin → Debug → LidPlate.Generator.AddIn.dll
Once selected the correct .dll �le, press the Install and wait until the add-in has been
installed.
E.1.2 Generate and save a lid plate model
The �rst functionality that the SolidWorks add-in o�ers is the generation of di�erent lid
plate models from a base model. Once the add-in has been installed, the required graphical
interface will be available showing the following task pane:
Figure E.2: Lid Plate Generator start task pane
To unlock the functional task pane of the add-in a valid base model has to be loaded to
SolidWorks. This base model can be found in the SolidWorks folder.After doing this, the
following task pane will be visible:
Figure E.3: Lid Plate Generator functional task pane
The detailed description of the full operative task pane can be seen in �gure E.4:
Figure E.4: Description of the functional task pane
So, the desired lid plate model has to be selected from the LID PLATE MODEL combo
box. The naming of the di�erent models follows the following logic:
MB OuterDiameter _ LidPressure _ LidPLatesNumber
The last component of the name represents how many lid plates like the one selected are
needed to complete a Mono Bucket lid. This will only appear if the number is di�erent
from 8. All the available models and their properties can be seen in table E.1:
Table E.1: Lid plate design variations
Model Lid pressure [KPa] Do [m] Di [m] Bulb plates α [◦]
MB9_200 200 9 2 8 20
MB9_300 300 9 2 8 20
MB9_400 400 9 2 8 20
MB10_200 200 10 2 8 20
MB10_300 300 10 2 8 20
MB10_400 400 10 2 8 20
MB10_400_6 400 10 2 6 30
MB10_400_12 400 10 2 12 15
MB10_400_15 400 10 2 15 12
MB11_200 200 11 2 8 20
MB11_300 300 11 2 8 20
MB11_400 400 11 2 8 20
MB12_200 200 12 2 8 20
MB12_300 300 12 2 8 20
MB12_400 400 12 2 8 20
MB12_400_12 400 12 2 12 15
MB12_400_15 400 12 2 15 12
Once the desired model has been selected, just by clicking the Generate button the base
model will be resized and scaled as the selected lid plate model.
If you want to recover the base model geometry, it can be done by clicking the Reset
button.
To save the generated lid plate model click the Save button and decide the location where
the model id going to be saved.
E.1.3 RAPID welding program generation
To generate the welding program that later will be loaded to RobotStudio to simulate the
process the desired lid plate model has to be generated. Then the WeldPaths sketch
has to be accessed to allow the add-in to take the geometrical information for the welding
coordinates de�nition. To do this right-click theWeldPaths sketch of the design tree and
select Edit Sketch.
Figure E.5: Edit WeldPaths sketch
Then select all the lines from the sketch and click the Generate RAPID program
button of the task pane and select the location where the �les are going to be saved. This
action will take some seconds, so wait until the light on the right side of the button turns
green to load the program to RobotStudio.
E.2 Robot Studio welding cell
E.2.1 Loading and positioning of a lid plate
Once the 3D model of the desired lid plate design has been generated, it has to be saved
as a .SAT �le. This type of �les is the only one that RobotStudio can work with.
To load .SAT model into RobotStudio's working environment follow the next steps:
1. Delete any exiting lid plate model.
2. Click Import Geometry from the Home tab and Browse for Geometry...
3. Search the .SAT �le that contains the desired lid plate model.
4. Double click the �le and wait until the model has been completely loaded to the
station.
With the model loaded to the station some positioning has to be carried out to arrange
the plate correctly in the station. To do so, follow this steps:
1. Select the loaded model in the weld station.
2. Go to Modify tab and click on Set Position and the following control panel will
appear:
Figure E.6: Set position control panel
3. For this application the translations and rotations that have to be introduced to
correctly position the lid plate are the ones shown in �gure E.6:
Position:
X = -400 mmY = 4600 mmZ = 900 mm
Orientation:
α = 90◦
β = 0γ = 0
After doing this the lid plate would be correctly positioned an ready to introduce its
welding program as is shown in �gure E.7:
Figure E.7: Lid plate model loaded and correctly positioned in the virtual welding station
E.2.2 Loading and setting a RAPID welding program
First of all, to be able to use the arc welding instructions of the RAPID programs the Arc
Welding Power Pack has to be installed. To load a RAPID welding program obtained from
the Lid Plate Generator the Arc Welding Add-in has to be activated on the Add-ins tab.
After doing this, follow the next steps:
1. Delete all existing points and paths from the tree on the Paths&Targets tab.
2. On theRAPID tab click Program and thenDelete Program to erase the existing
program from the virtual controller.
3. Click again Program and Load Program....
4. Search the location where the folder with all the program �les are saved.
5. Select the .pgf �le and load it.
6. Synchronize all the information of the RAPID program to the station marking all
the check boxes that appear on the next window:
Figure E.8: Load to Station check box window
7. Wait until the synchronization process ends.