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Simulation of robot paths and heat effects in welding

Ericsson, Mikael LU (2006)
Abstract (Swedish)
Popular Abstract in Swedish

Svetsning är en av de viktigaste tillämpningarna för robotar är inom tillverkningsindustrin. Normalt så programmeras roboten genom att operatören guidar manuellt robotarmen mellan de olika robotkoordinaterna. För att förbättra noggrannheten vid programmeringen kan man använda ett simuleringsverktyg, så kallat Computer Aided Robotics (CAR). Simulering kan även vara ett kraftfullt verktyg för utvärdering och minimering av oönskade spänningar och deformationer.



Syftet med denna avhandling är att utveckla ett simuleringsverktyg samt en metod där man kan analysera robotbanor, temperatur förloppet, restspänningar och deformationer. Detta möjliggjordes genom att integrera ett robot... (More)
Popular Abstract in Swedish

Svetsning är en av de viktigaste tillämpningarna för robotar är inom tillverkningsindustrin. Normalt så programmeras roboten genom att operatören guidar manuellt robotarmen mellan de olika robotkoordinaterna. För att förbättra noggrannheten vid programmeringen kan man använda ett simuleringsverktyg, så kallat Computer Aided Robotics (CAR). Simulering kan även vara ett kraftfullt verktyg för utvärdering och minimering av oönskade spänningar och deformationer.



Syftet med denna avhandling är att utveckla ett simuleringsverktyg samt en metod där man kan analysera robotbanor, temperatur förloppet, restspänningar och deformationer. Detta möjliggjordes genom att integrera ett robot simuleringsprogram med ett finita elementprogram. Ett speciellt interface skapades mellan de olika programvarorna vilket möjliggjorde ett informationsutbyte. För att validera metoden så jämfördes resultat från simuleringar med experimentella mätningar.



Metoden användes för att programmera svetsbanor, både för plana plåtar samt för en komponent med komplex geometri. De genererade svetsbanorna överförs från robot simuleringsprogrammet till finita elementprogrammet där predikteringar av temperatur och restspänningar genomfördes. God överensstämmelse uppnåddes mellan programmerad robotbana och uppmätt robotbana. Temperaturmätningar genomfördes med både termoelement och en infraröd kamera. Mätresultat från de båda olika metoderna samt predikterade och uppmätta temperaturförlopp gav god överensstämmelse.



Predikterade restspänningar jämfördes med neutrondiffraktion mätningar med en godtagbar överensstämmelse. En speciell systemarkitektur togs fram för att möjliggöra tidssynkronisering mellan de olika simuleringssystemen. Slutligen utvecklades en algoritm för optimering av svetshastighet för att minimera deformation.



Arbetet kan betraktas som en grund till ett simuleringsverktyg där exempelvis robotbanor, svetssekvenser och fixturlösningar kan utvärderas och optimeras före tillverkning. (Less)
Abstract
The objective of this thesis is to develop a simulation tool and a method by which robot trajectories, temperature histories, residual stresses and distortion can be analysed and optimized off-line. This was performed by integrating robot simulation software with finite element analysis software. A special interface was created which facilitated information exchange between the two software programs. To validate the method comparisons were made between simulation results and measurements during real welding.



The method was used to program welding trajectories, both for planar plates and for parts with complex shapes. The welding trajectories were downloaded to the finite element analysis software where temperature and... (More)
The objective of this thesis is to develop a simulation tool and a method by which robot trajectories, temperature histories, residual stresses and distortion can be analysed and optimized off-line. This was performed by integrating robot simulation software with finite element analysis software. A special interface was created which facilitated information exchange between the two software programs. To validate the method comparisons were made between simulation results and measurements during real welding.



The method was used to program welding trajectories, both for planar plates and for parts with complex shapes. The welding trajectories were downloaded to the finite element analysis software where temperature and residual stress prediction were performed. Good agreement was found between the programmed robot trajectory, and the actual trajectory, necessitating only minor adjustments. Temperature measurements were performed using both thermocouples and infrared imaging. Good agreement was also found between the results using these two methods, as well as between predicted and measured temperatures.



Predicted residual stress distributions were compared with neutron diffraction measurements and fair agreement was found. A specified software architecture was developed which allowed full time synchronization between different simulation systems. Finally, weld velocity optimization was performed through a developed algorithm making it possible to minimize distortion.



The research conducted in the present work indicates that the models and computer programs that were developed could be combined to create powerful tools for the evaluation and optimisation of welding processes. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Assoc Professor Madsen, Ole, Aalborg University
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Produktionsteknik, Welding, Automation, robotics, Off-line programming, Robotics, Automatiska system, Production technology, control engineering, Finite Element Analysis, reglerteknik, robotteknik
pages
160 pages
publisher
Department of Mechanical Engineering, Lund University
defense location
Room C118, Department of Technology, Mathematics and Computer Science, University West, Trollhättan
defense date
2006-06-08 10:15
ISBN
978-91-628-6869-7
language
English
LU publication?
yes
id
5043631f-9254-46d0-a707-de049deff6f2 (old id 546917)
date added to LUP
2007-09-06 16:12:51
date last changed
2016-09-19 08:45:08
@phdthesis{5043631f-9254-46d0-a707-de049deff6f2,
  abstract     = {The objective of this thesis is to develop a simulation tool and a method by which robot trajectories, temperature histories, residual stresses and distortion can be analysed and optimized off-line. This was performed by integrating robot simulation software with finite element analysis software. A special interface was created which facilitated information exchange between the two software programs. To validate the method comparisons were made between simulation results and measurements during real welding.<br/><br>
<br/><br>
The method was used to program welding trajectories, both for planar plates and for parts with complex shapes. The welding trajectories were downloaded to the finite element analysis software where temperature and residual stress prediction were performed. Good agreement was found between the programmed robot trajectory, and the actual trajectory, necessitating only minor adjustments. Temperature measurements were performed using both thermocouples and infrared imaging. Good agreement was also found between the results using these two methods, as well as between predicted and measured temperatures.<br/><br>
<br/><br>
Predicted residual stress distributions were compared with neutron diffraction measurements and fair agreement was found. A specified software architecture was developed which allowed full time synchronization between different simulation systems. Finally, weld velocity optimization was performed through a developed algorithm making it possible to minimize distortion.<br/><br>
<br/><br>
The research conducted in the present work indicates that the models and computer programs that were developed could be combined to create powerful tools for the evaluation and optimisation of welding processes.},
  author       = {Ericsson, Mikael},
  isbn         = {978-91-628-6869-7},
  keyword      = {Produktionsteknik,Welding,Automation,robotics,Off-line programming,Robotics,Automatiska system,Production technology,control engineering,Finite Element Analysis,reglerteknik,robotteknik},
  language     = {eng},
  pages        = {160},
  publisher    = {Department of Mechanical Engineering, Lund University},
  school       = {Lund University},
  title        = {Simulation of robot paths and heat effects in welding},
  year         = {2006},
}