Development Of A Mechanical Accessory For Quality Control...

Development of a Mechanical Accessory for Quality Control in Industrial Topographic Survey, (7112) Carlos Aurélio Nadal, Pedro Luis Faggion and Leonardo Ribas Précoma (Brazil) FIG Congress 2014 Engaging the Challenges – Enhancing the Relevance Kuala Lumpur, Malaysia 16-‐21 June 2014

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Development Of A Mechanical Accessory For Quality Control In Industrial Topographic Surveys

Carlos Aurélio NADAL, Pedro Luis FAGGION and Leonardo Ribas PRÉCOMA, Brazil

Key words: Industrial Topographic survey, industrial topography, metrology

SUMMARY

A new accessory is being developed at the Federal University of Paraná in order to provide quality control for industrial topographical precision surveying whose main objective is to metrologically verify small displacements and rotations of controlled mechanical instruments for computationally industrial platforms.

We tested a system composed of a Leica TC2003 total station and an accessory which consists of supports with two or more glass mini prisms spaced approximately 20cm apart. The accessory was calibrated with the help of a laser interferometer that provided the spatial distance between the centers of the glass mini prisms . With this system, it is possible to determine the inclination of the bar and its displacements (spatial rotations and translations). Initially simulations and tests were carried out in the laboratory to determine the pitch of the bar and compare data with the results from the Talyvel level. Other actual tests were performed on a machine in the UFPR Mechanical Engineering laboratories. The results obtained showed the potential of the system for use in the calibration and certification of mechanical instruments similar to those tested.


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Development Of A Mechanical Accessory For Quality Control In Industrial Topographic Surveys

Carlos Aurélio NADAL, Pedro Luis FAGGION and Leonardo Ribas PRÉCOMA, Brazil

1. INTRODUCTION

Since antiquity, manufacturing processes have evolved by mechanical means, and at a particularly rapid pace over the last century, especially with machining processes. This has a very important role in our day to day lives, as almost everything we use has machined parts. Some examples are the automobile, surgical equipment, electronics, and even jewelry. (ÁGFALVI et al., 2006)

Considering the industrial revolution, progressive policies, and globalization, there has been great technological advancement, particularly in the area of information technology. This advance in information technology has expanded its applications to other areas, one of which is machining. This expansion enabled the emergence of technology that is today known as CNC (computer numerical control) and more recently that of robotics technology. These technologies have emerged from the need to reduce costs, increase speed, and improve constancy in productivity. (STOETERAU 2004)

When it comes to machining using manual machines, the operator exerts a much larger role in manufacturing the parts, since he performs several steps in the process, thereby correcting those from systemic errors in the machine tool (both tool and machine wear) leaving only human errors (incorrect observations, lack of attention, etc.) as the cause of any errors presented in final production. (ÁGFALVI et al., 2006)

When referring to the quality of parts produced by a CNC milling machine, we depend on near absolute performance, accuracy, and mainly constancy, so that the machine can operate.

Problems that the machine may present in these aspects will inevitably reflect in quality control, sudden interruptions in production, and lot after lot of parts that are totally lost. For these reasons, it is very important to routinely check the performance of a machine tool before running large lots.

There are many factors that can cause a part to have manufacturing defects, such as serious errors in the design of the part itself, the machine kinematics, or even incorrect


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machine assembly (lack of rigidity in the machine structure, symmetry, poorly made foundations, etc.). All this control is implemented with methods of industrial metrology (Silva, 1999) which has industrial topography as one of its tools. (NADAL 2000)

There are many specific pieces of equipment on the market that utilize several distinct methods to perform the verification of machine tools, many of these are said to use industrial topography but have high cost. This actually ended up giving us opportunities to develop methods that rely on the usual topography equipment. (ETALON, 2013; FRASER, 1998; NIKON METROLOGY, 2013)

In proposing the use of conventional topography equipment in a machine tool, the obstacle of satisfactorily affixing the target elements on the work space was an issue, as well as doubt about whether in small spaces one could achieve the precision required to stay within the parameters of volumetric compensation (correcting errors caused by the machine). (Wang, 2012)

Against this background, solutions were proposed to affix 1 mini prism and 2 mini prisms on the work table of a machining center and then obtaining the difference between the values of the slope and distance measurement through a total station and metrology equipment.

2. DEVELOPMENT OF ACCESSORIES

Using a LEICA GMP111-0 mini prism, which has a bubble level, a removable lower pin, and threaded rods for the operator to fit on top, it was possible to fabricate a support for the prism. This allowed for ease of leveling the mini prism which was rigid and did not require the presence of an operator to hold it.

The project was designed to maintain the standard height of the prism, using a mass support pin as a guide, a plate with a hole for the center pin, and screws in the 4 corners, where the possibility of setting the prism would open slots in the ends of the bolts as in FIGURE 1.


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Figure 1 - Prototype support for mini prism developed as a first project.

With the success in the calibration and stability tests for the mono prism support, the manufacturing for the bi prism support was started using the same idea as the mono prism support, but with drilling for affixing two prisms, as shown in Figure 2.

Figure 2 - Prototype supports two miniature prisms.

To facilitate the studies of change in the combined level, a table was developed that allowed for the adjustment of tilt by 4 threaded screws at both ends. The table was made of carbon steel plate with dimensions of 220x300mm as in Figure 3.


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Figure 3 - Table for testing the efficiency of mini-prisms

3. EQUIPMENT USED IN TESTS AND MEASUREMENTS

We used a Leica TC2003 Total Station, with ATR (automatic target recognition) able to perform measurements automatically at regular intervals with a nominal angular accuracy of 0.5" and linear accuracy of 1mm + 1ppm (LEICA GEOSYSTEMS, 2013).

We also used the HP 5528A interferometer installed at the UFPR Laboratories. This equipment is regularly used to calibrate invar sights used in high accuracy leveling, and provides measurements accurate to 1 micron, which exceeds the precision necessary to perform calibration of the supports.

In tests on the accuracy of the supports, a Taylor-Hobson Talyvel 5 electronic level, from the UFPR laboratories, with a nominal accuracy of 3mm/ m. The level can be seen in Figure 4.

Figure 4 Talyvel Level Sensor used in conjunction with accessory developed.


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The Leica GMP111-0 mini prism is small in size, made from high quality optical glass, and has reflective surfaces coated with material that prevents impairment by dirt or condensation. It offers great positional accuracy due to its small size, with a leveling bubble and attachable pin with 1/4" thread (LEICA GEOSYSTEMS, 2013)

4. TESTS PERFORMED AND RESULTS OBTAINED

In the first experiment we tested the inclination measurement of the system.

Position 1. With the system placed on the leveled table, we determined the slope between the two prisms using the Talyvel level and the distance determined in calibration with the HP 5528A interferometer as standards. The three-dimensional coordinates of the prisms were obtained by topographic irradiation with the TC 2003 total station, with 3 sets of double position measurements taken from the telescope and positioned 2m from the system.

Distance between prisms HP5528A 0.1995272m Distance obtained by irradiation 0.2003 m Slope provided by Talyvel 0.002 mm/m Slope obtained with total station 0.0018 mm/m Source: Précoma 2013

Position 2. By using the screws, the table was tilted maintaining the total station at 2m from the system, yielding the following results:

Distance between prisms HP5528A 0.1995272m Distance obtained by irradiation 0.2002 m Slope provided by Talyvel -3.216 mm/m Slope obtained with total station -3.431 mm/m Source: Précoma 2013

Position 3. The table slope was maintained and the total station moved to 4m from the system, yielding the following results:

Distance between prisms HP5528A 0.1995272m Distance obtained by irradiation 0.2010 m Slope provided by Talyvel -3.216 mm/m Slope obtained with total station -3.548 mm/m Source: Précoma 2013

In the second test was used with the three prisms and the individual support. This test was conducted directly at the UFPR machining center by Cartographic Engineering


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students in their final year of study, and guided by Professors Carlos Nadal and Peter Faggion. We used the same equipment described above, and the procedure was to verify the conditions of coplanarity and perpendicularity between axes and planes of a Romi Bridgeport Discovery machine, belonging to the UFPR machining center.

The coordinates obtained for three targets with the movements carried out by the machine tool with points 1,2 and 3 (figure 5) fixed on the table of machine, We use index point coordinates 0 , 1 and 2 for the different positions obtained by displacements of the machine.

Figure 5 Interior of Romi Bridgeport machine, where the experiments were carried out.

point X0(m) Y0(m) Z0(m) X1(m) Y1 (m)

Z1 (m) X2(m) Y2(m) Z2(m)

1 0.000 -2.627 -0.596 0.014 -3.186 -0.596 0.178 -3.182 -0.596 2 0.026 -3.454 -0.597 0.040 -4.013 -0.598 0.204 -4.009 -0.598 3 0.354 -2.618 -0.600 0.367 -3.177 -0.600 0.531 -3.173 -0.600 Source: (Nadal, 2013)

Applying the Bursa-Wolf transformation model consisting of rotations (R) followed by scale difference ( )σ and a translation ( )Δ expressed by the Bursa-Wolf formula (Veiga et al., 2004).


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⎥⎥⎥

⎦

⎤

⎢⎢⎢

⎣

⎡

⎥⎥⎥

⎦

⎤

⎢⎢⎢

⎣

⎡

−

−

−

=

⎥⎥⎥

⎦

⎤

⎢⎢⎢

⎣

⎡

≡Δ+=

zyx

kk

wvu

RXU1

11

ωϕ

ω

ϕ

σσ +⎥⎥⎥

⎦

⎤

⎢⎢⎢

⎣

⎡

Δ

Δ

Δ

zyx

where ω , ϕ , and k are very small angles, which (in radians) express three successive rotations about the x , y, and z axes, respectively, with σ as a scaling factor, close to the unit and ( zyx ΔΔΔ ,, ) as the components of a translation vector.

With the above data, applying the method of least squares, it was possible to get the result shown in the table below for this work. The results obtained with the Machine Romi Bridgeport Discovery are compared.

Stage σ Ω (rad) Φ (rad) Κ (rad) Δx (m) Δy (m) Δz (m) 01 1.00069 -0.00041 -0.00033 0.00001 0.014 -0.561 0.001 Romi 0.5588 02 1.00000 0.00000 0.00000 0.00000 0.164 0.004 0.000 Romi 0.1650

CONCLUSIONS AND RECOMMENDATIONS

The goals set were achieved successfully, all prototypes showed significant results for the contribution in raising techniques employed by subjecting them to precision levels below those specified for some equipment, as well as results developed by the writers’ own scientific research.

The support developed for the mono prism fulfilled its objectives, with ease of calibration and stability, and extremely low manufacturing cost. It is worth emphasizing that there is an influence of temperature on the diameter of the sliding hole, and with aluminum as the support part material, which has a high coefficient of expansion within the group of metals, colder ambient temperatures have indicated a fitting difficulty, while warmer environments have shown the emergence of small clearances.

The bi prism support presented difficulty in setting the prisms, because they are two rigidly interconnected points, and also showing the possibility of errors occurring in the orthogonality in the implementation of sliding drill for pin insertion, this indicates that reproduction requires care in drilling the holes.

With respect to stability, it was shown to be as efficient as a mono prism in that costs are also low, and the characteristics with respect to temperature variation are


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maintained. The caveat in this case is that since there are two prisms the temperature will directly influence the distance between them. This issue may have influenced the differences in distances between points "A" and "B" in the readings obtained with the total station compared to those obtained with the interferometer. However, as there was no monitoring of ambient temperatures during the tests, it is impossible to model and prove these influences.

Some recommendations for future research within the subject matter covered by this work for the prism mono support is to replace the sliding hole for the prism pin with a machined channel for the placement of a rubber O-ring, so there is a forced centering of the piece. Another recommendation would be to choose another material for the manufacture of the support that does not have such a high coefficient of thermal expansion.

The bi prism support should consider the same considerations, adding only the influence of temperature on the distance between points "A" and "B".

REFERENCES

ÁGFALVI, M.; BOKOR, Z.; FARKAS, R.; GYENES, R.; TARSOLY, P. GEODETIC CONTROL AND SETTING MEASUREMENTS IN MECHANICAL METROLOGY. Shaping the Change XXIII FIG Congress Munich, Germany, October 8-13, 2006.

ETALON AG. Disponível em <http://www.etalon-ag.com/> Acesso realizado em 5 de dezembro de 2013.

FRASER, C. S. STATE OF THE ART IN INDUSTRIAL PHOTOGRAMMETRY. Invited Paper, Geodetic Services. Melbourne, Florida, USA, 1988.

LEICA GEOSYSTEMS. Disponível em <http://www.leica-geosystems.com> Acesso realizado em 29 de novembro de 2013.

NADAL, C. A. MÉTODO DA INTERSEÇÃO ÓPTICA TRIDIMENSIONAL APLICADO À ENGENHARIA DE PRECISÃO. Tese apresentada ao Curso de Pós-Graduação em Ciências Geodésicas da Universidade Federal do Paraná para obtenção do grau de Doutor. Curitiba, 2000.

NIKON METROLOGY. Disponível em <http://www.nikonmetrology.com/> Acesso realizado em 5 de dezembro de 2013.

PRÉCOMA, L.R. TOPOGRAFIA INDUSTRIAL – DESENVOLVIMENTO E CALIBRAÇÃO DE SUPORTES PARA MINI PRISMAS OBJETIVANDO A SUA UTILIZAÇÃO EM CENTROS DE USINAGEM. Monografia apresentada ao Curso de


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Graduação em Engenharia Cartográfica e de Agrimensura, Departamento deGeomática, setor de Ciências da Terra da Universidade Federal do Paraná. Curitiba, 2013.

RENISHAW. Disponível em <http://www.renishaw.com.br> Acesso realizado em 5 de dezembro de 2013.

STOETERAU, R. L. INTRODUÇÃO AO PROJETO DE MÁQUINA-FERRAMENTAS MODERNAS. Apostila da disciplina de Projeto de Máquinas-ferramentas do Curso de Engenharia Mecânica da Universidade Federal de Santa Catarina. Florianópolis, 2004-1.

TAYLOR-HOBSON. Disponível em <http://www.taylorhobson.com.br> Acesso realizado em 9 de dezembro de 2013.

VEIGA, L. A. K.; ZANETTI, M. A. Z.; FAGGION, P. L. FUNDAMENTOS DE TOPOGRAFIA. Apostila destinada aos alunos das disciplinas de Topografia I e Topografia II do Curso de Engenharia Cartográfica e de Agrimensura e demais cursos da Universidade Federal do Paraná. Curitiba, 2012.

WANG, J. D.; GUO, J. J. RESEARCH ON VOLUMETRIC ERROR COMPENSATION FOR NC MACHINE TOOL BASED ON LASER TRACKER MEASUREMENT. Science China Technological Sciences, November 2012, Volume 55, Issue 11, pp 3000-3009.


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CONTACTS Prof. Dr Carlos Aurélio Nadal Prof. Dr. Pedro Luis Faggion and Eng. Leonardo Ribas Précoma

Universidade Federal do Paraná

Setor de Ciências da Terra

Departamento de Geomática

Curitiba-Parana - Brasil

cnadal @ufpr.br

[email protected]

[email protected]

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