Seam tracking during laser beam welding of tailored blanks with vision sensor

Abstract

The main challenges in modern design of automobile bodies are reduction in weight and maximization of the structural stiffness and passive safety. The “tailored blank” has contributed to achieving a significant weight reduction which is single flat sheets joined by laser welding into the desired configuration without filler wire. Production of laser beam welded tailored blanks requires high speed, high precision and high quality. The welding robots that follow a preprogrammed path are often not able to guarantee a sufficient weld seam quality. Therefore, a seam tracking system is used to improve the reliability of the seam quality prediction. This paper describes the development of the seam tracking system for laser beam welding of tailored blanks. The system consists of DSP based vision camera and stripe-type laser diode. The total system is assembled into a compact module which can be attached ahead of welding torch. The images taken by the camera are analyzed using image processing algorithms. The image processing algorithms for extracting the feature points of weld seam are discussed depending on the characteristics of laser beam welding of tailored blanks. The accuracy of the industrial robots during the laser welding process was guaranteed by the compensation method A prototype sensor system has been developed and experimental results show its effectiveness and good performance.The main challenges in modern design of automobile bodies are reduction in weight and maximization of the structural stiffness and passive safety. The “tailored blank” has contributed to achieving a significant weight reduction which is single flat sheets joined by laser welding into the desired configuration without filler wire. Production of laser beam welded tailored blanks requires high speed, high precision and high quality. The welding robots that follow a preprogrammed path are often not able to guarantee a sufficient weld seam quality. Therefore, a seam tracking system is used to improve the reliability of the seam quality prediction. This paper describes the development of the seam tracking system for laser beam welding of tailored blanks. The system consists of DSP based vision camera and stripe-type laser diode. The total system is assembled into a compact module which can be attached ahead of welding torch. The images taken by the camera are analyzed using image processing algorithms. The imag...