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Simulation of the Metal Spinning Process by Multi-Pass Path Using
AutoCAD/VisualLISP
Alexandru C. FILIP, Ion NEAGOE
Department of Manufacturing Engineering
University TRANSILVANIA of Brasov
Bdul Eroilor nr.29, 500036-BRASOV
ROMANIA
[email protected], [email protected]
Abstract: - Metal spinning on NC machine-tools is a complex flexible manufacturing method with high efficiency for
small and single series of parts. The algorithms which describe the roller trajectory during the process are complicated
and hard to understand. This paper presents an application developed under Visual LISP environment which simulates
the metal spinning process by multi-pass path for rotational sheet parts, cylinders and cones. The simulation is based on
some algorithms created by the authors in previous research and is a convenient tool for professionals to test the
manufacturing process before the real production. The application is user-friendly, simple and intuitive.
Key-Words: - Metal spinning, simulation, Multi-pass, Hollow parts, VisualLISP
1 Introduction Among the available CAD tools used today in
engineering [1], [2], [9] the computer simulation is a
versatile tool for developing applications to check the
correctness of the theoretical approaches of a certain
engineering issue. When manufacturing parts, the
computer simulation determines the possible defect of
the predicted technology before the part is really
manufactured, reducing the costs of preparing
production.
The basic scientific method of simulation is the
numerical one, e.g. FEM, which is very used also in
metal spinning [3], [4], [5]. But this method is a rather
complicated one, which demands good knowledge of
plastic behaviour of materials, mathematics etc. and it
needs a relatively expensive dedicated software.
This paper proposes a simplified graphical simulation
of the roller’s trajectory, during the process of metal
spinning by multi-pass path.
The simulation is based on previous research,
developed by the authors [6], [7], [8], for the
manufacturing process of metal spinning of hollow parts.
The authors chose for the simulation the AutoCAD
environment, because it is one of the most known basic
CAD software. Besides the drawing possibilities, this
software provides an integrated programming
environment, VisualLISP, which allows developing user
applications.
The manufacturing of rotational hollow parts by
spinning is a method with high technological flexibility.
The method can be applied on common machine-tools
(like lathes) or on modern ones, like NC lathes. It has a
high efficiency for small and very small series of parts.
The NC lathes can provide different complex trajectories
of the forming tools, for any configuration of the
rotational hollow part. Usually, these equations are
complicated and their accuracy is hard to establish by
other methods than by computer simulation.
The most complex method of metal spinning is the
multi-pass one. Therefore, this method was chosen to be
implemented in the application, based on some
algorithms for calculating the successive positions of the
forming roller, previously tested by the authors of the
present research. The shape of the parts can be
cylindrical or conical as well.
2 Algorithms used for metal spinning by
multi-pass path
2.1 Case of cylindrical parts When manufacturing metal cylinders by spinning
with a multi-pass path, the roller’s trajectory is
established depending on the shape and dimensions of
the part. It implies the calculus of the coordinates of the
specific points of the inner profile of the part at each
passing of the roller and the calculus of the coordinates
of the specific points of the equidistant profile, which is
the trajectory of the roller’s radius centre.
Cylindrical parts are in two types – flangeless or with
a flange. The process of spinning of flangeless parts is
simpler, as there is no risk of interference between the
roller and the flange during the forming stage. In this
case, the most used algorithm for a multi-pass path is the
one when the part is formed at both the direct and the
return travel of the roller (fig.1).
Latest Trends on Engineering Mechanics, Structures, Engineering Geology
ISSN: 1792-4294 161 ISBN: 978-960-474-203-5
The spinning of cylindrical parts with a flange is
done [6] in two stages of processing (fig.2):
a) during the first stage, the cylindrical wall of the part
is formed on the mandrel, both at direct and return
travel of the roller, using a trajectory similar with
the one used for manufacturing flangeless parts.
This stage takes place until the preformed flange
makes collision with the second step of the
mandrel. So, the last travel of the roller, during this
stage, (fig.2), will be 1rn1 → 2rn1;
b) during the second stage, the flange is formed, only
at the return travel of the roller, towards the
mandrel. The starting point, for all steps, is the
point 2rn1. The direct travel of the roller is, in fact, a
free one, towards the point 2rn1.
The calculus of the coordinates of the characteristic
points, marking the centre of the roller radius, (fig.2) is
done with the following equations:
Rg2
dx
ir1 ++= ; (1)
( ) z1
1 l1isin
cos1Rz
1
ir−−
−=
α
α; (2)
i
ir2 cosR
2
Dx
iα+= ; (3)
( ) ziii
r2 l1isinRctg2
dDz
i−−+⋅
−−= αα . (4)
The equations above are determined considering a
coordinate system XOZ, with the X axis along the part’s
radius and the Z axis along its symmetry axis.
2.2 Case of conical parts The spinning of cones by multiple passes can be
done by several methods. The authors of the present
paper proposed a new path of the roller’s trajectory, [7],
which improved the manufacturing productivity and the
part’s accuracy.
The scheme of manufacturing, based on the new
path, (fig.3) is based on the principle of forming the
part’s wall at both the direct and the return travel of the
roller, by using certain spacing, lz, measured on an axial
direction and a certain decrease rate, ∆α, of the path’s
angle from a direct pass to the next one.
The characteristic points of the path were considered
the points of the roller’s centre of roundness.
The coordinates of the points 1r1 and 2r1 of the roller
path at the first direct travel can be calculated with
similar equations as in the case of cylindrical axi-
symmetric parts, as following:
11 cos21
αRd
xr
+= ; (5)
Fig.2 The scheme of spinning by multi-pass
path of cylindrical parts with a flange
Fig.1 The scheme of spinning by multi-pass path of
flangeless cylindrical parts
Fig.3 The scheme of spinning by multi-pass path of
conical parts
Latest Trends on Engineering Mechanics, Structures, Engineering Geology
ISSN: 1792-4294 162 ISBN: 978-960-474-203-5
11 sin1
αRzr= ; (6)
1
12
1r2 cosR
2
Dx
2
Dx
1α∆ +=+= ; (7)
1
1
1222 sin
211α
αR
tg
dDzzz r +
−−=∆+−= . (8)
At a certain pass “i” of the roller, the coordinates of
the start and end points of the path, are calculated with
the following equations:
– for the start points:
( ) ϕ−+= tglixx zrir1
111 (9)
( ) zlizzrir
1111 −−= ; (10)
– for the end points:
ii
2 cosR2
Dx
irα+= ; (11)
( )( ) izi
i Rltgitg
dDz
irαϕ
αsin11
22 +−−+
−−= .(12)
The shape of the trajectory assessed with the above
equations is strongly influenced by the geometrical
shape and dimensions of the part and by some main
technological parameters, such as:
– α1, the roller trajectory’s angle, at the first pass;
– ∆α, the decreasing value of the roller trajectory’s
angle, from one pass to another;
– lz, the roller’s step distance.
The minimum value of the angle α1, meaning the
deviation of the part generatrix at the first passing,
usually [8] depends on the parts’ diameter, the blank’s
diameter, thickness and mechanical properties and on the
feeding rate.
The decreasing value ∆α is, usually, for steel, 1…3°
and for aluminium, 3…6°. The step distance lz influences the number of passings
for a complete processing of the part. If the spacing lz is
too big, the material looses its stability and the part’s
wall wrinckles. The value of the step distance lz depends
[8] on the roller’s radius R and cannot overpass it’s
double, lz≤2R. The maximum value of the step distance
lzmax is calculated with the equation:
Rkkl bgz ⋅⋅⋅= 2max
, (13)
where kg is a coefficient considering the influence of the
material thickness [8] and kb is a coefficient considering
the influence of the planar flange width of the blank [8].
With the equations (1)…(12) a calculus is made for a
certain case of study, giving different values of the main
parameters which have an important influence on the
process. This activity is very laborious and a computer
application will make it easier and more precise.
Besides the advantage of facilitating the engineer
work, a suitable computer application can make data
exchange [9] with the manufacturing equipment or other
entitities such a virtual reality environment.
3 The EduSpin application For simulation purposes there was designed an
integrated application. The user can view a simple
simulation of the process of metal spinning and better
understand the influence of the geometrical and
technological parameters on the roller’s trajectory.
The application was developed under the AutoCAD
environment, which is very suitable for graphic
simulations, because it has drawing capabilities and an
integrated programming language, Visual LISP, which
can be used for designing user applications.
The application, named EduSpin 1.0, integrates three
user functions for the simulation of the roller’s trajectory
in three cases studied by the authors:
– TraCil – for flangeless cylindrical parts;
– TraCilFl – for cylindrical parts with a flange;
– TraCon – for conical parts.
The application has a modular structure. This kind of
programming assures an easy debugging and easier
future developments.
Once the application is launched, a main dialog box
(fig.4) is opened. It contains selection and edit boxes, for
selecting and introducing of all parameters needed for
the calculus and the simulation of the manufacturing
process.
After the data input, the user launches the simulation
and surveys the screen. The speed of the simulation can
be adjusted at any value according to any desire.
Each function draws a simplified version of the
technological scheme (fig.5 and 6) with all the
characteristic points of the path and creates a simple text
file with the values of their coordinates, for future NC
programming purposes.
Fig.4 Main dialog box of EduSpin 1.0 application
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ISSN: 1792-4294 163 ISBN: 978-960-474-203-5
Fig.6 Simulation of metal spinning for conical parts
Fig.5 Simulation of metal spinning for cylindrical parts with a flange
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ISSN: 1792-4294 164 ISBN: 978-960-474-203-5
The calculation of the coordinates of the
characteristic points is done with the equations
determined in the algorithms presented in chapter 2,
namely the equations (1) to (12).
The results of any simulation can be recorded for
further study or distribution via the usual options of
saving files in AutoCAD environment.
For example, when manufacturing parts made of soft
steel DC 04 SR EN 10130 +A1, some values for the
simulation can be according to the following:
• inner cylindrical diameter, d=60…80 mm;
• flange diameter, dfl=100…120 mm;
• part height, h=40…60 mm;
• sheet thickness, g=1…2 mm.
The results of the simulation (fig.5 and 6) can be
viewed and analysed and conclusions can be drawn.
When modifying one or several process parameters, their
influence is easily observed and the process of metal
spinning is better understood even without practical
activities of manufacturing real parts.
4 Conclusion The EduSpin 1.0 application is an example of using a
common CAD environment, like AutoCAD, for
simulation purposes in the domain of industrial
engineering.
Compared to all other methods of simulation of a
deformation process, this application is simple and
intuitive, being a useful tool for engineers to test the
accuracy of the technological design before the real
production, thereby reducing the costs.
The application development under a graphical
environment such AutoCAD allowed the simulation of
the spinning process, according to the values of the
parameters given by the user.
It is worth mentioning that among the range of
applications of simulation of a manufacturing process,
this application is less expensive, being used even in the
process of teaching at the authors’ university.
Further development is foreseen to allow the
application to simulate the metal spinning process for
any shape of symmetrical hollow part and to extend the
simulation to the 3D level. At the same time, this method
is intended to be developed for other cold-forming
operations such as bending or deep-drawing.
References:
[1] Babich, A. Mavrommatis, K.Th. Teaching of
Complex Technological Processes Using
Simulations. International Journal of Engineering
Education. Vol.25, No.2, Tempus Publications, 2010.
[2] Cerra, P.P. Penin, P.A., Diaz, R.G. Morales, R.P.
3D-CAD learning environment through interactive
modular system (AIMECDT-3D, Computer
Applications in Engineering Education, Wiley
Periodicals, Inc., Vol.18, Issue 1, 2009.
[3] Hamilton, S., Long, H. Analysis of conventional
spinning process of a cylindrical part using finite
element methods. Proceedings of the 12th
International Conference on Metal Forming, vol.1,
2008, Cracovia.
[4] Liu, C.H., The simulation of the multi-pass and die-
less spinning process. Journal of materials
processing technology. No.192-193, Elsevier
Science, 2007.
[5] Music, O., Allwood, J.M., Kawai, K., A review of
the mechanics of metal spinning. Journal of
materials processing technology. No.210, Elsevier
Science, 2010.
[6] Neagoe, I., Filip, A.C., Researches on the Roller
Trajectory when Manufacturing Cylindrical Hollow
Parts with a Flange by Spinning. (part two -
Validation by Computer Simulation of the Roller
Trajectory). Sbornik dokladi ot treta Konferentia s
mejdunarodno uceastie “Masinoznanie I masinni
elementi”, 2006, Technical University of Sofia.
[7] Neagoe, I., Filip, A.C. Algorithm and Computer
Simulation of the Roller Working Trajectory for the
Spinning of Cones. The 3nd
International Conference
on Integrated Engineering. Published in the
Academic Journal of Manufacturing Engineering,
vol.6, issue 3/2008, Editura Politehnica Timişoara.
[8] Neagoe, I., Filip, A.C. New Mathematical Models of
the Technological Parameters at Axi Symmetric
Sheet Metal Spinning. The 3nd
International
Conference on Integrated Engineering. Published in
the Academic Journal of Manufacturing Engineering,
vol.6, issue 2/2008, Editura Politehnica Timişoara.
[9] Oancea, G., Garbacia, F., Nedelcu, A., Software
module for data exchange between AutoCAD and a
virtual reality system, Product engineering - Tools
and methods based on virtual reality, vol. 35, 2008,
Springer Netherlands, pp. 383-394.
Latest Trends on Engineering Mechanics, Structures, Engineering Geology
ISSN: 1792-4294 165 ISBN: 978-960-474-203-5