Naoki Kawada

Development of Quality Control System for Laser Spot Welding System of Stainless Steel Sheets

It is necessary to manage not only in-process but also pre-process and post-process for improvement of the welding quality. In this paper, the fault condition sensing technique is proposed by the waveform monitoring and the waveform analysis of the physical quantity in the welding process. The waveform monitoring is applying control chart method in quality control. The waveform analysis such as running average process, differential characteristics, integral characteristics and time subtraction of data are particularly effective for monitoring a laser welding system. Application of the technique to the laser-half-penetration-spot-welding for thin stainless steel sheets is discussed. This monitoring system was verified by the welding examination with pulse gating mode Nd:YAG laser welding system. Welding conditions as follows; peak power is 4kW, pulse width is 30ms, processing speed is 1.5m/min, and assist gas is Argon. These successful results were very promising.

Development of monitoring system for laser welding system of thin stainless steel sheets by waveform analysis

The method of the quality control in the laser welding system has various techniques. It is necessary to manage not only in-process but also pre-process and post-process for improvement of the welding quality. In this paper, the fault condition sensing technique is proposed by the waveform analysis of the physical quantity in the welding process. The waveform analysis such as running average process, differential characteristics, integral characteristics and time subtraction of data are particularly effective for monitoring a laser welding system. Application of the technique to the half penetration welding with the Nd:YAG laser for thin stainless steel sheets is discussed. At first an installation state to a jig of materials end paid its attention to a phenomenon to influence a welding processing characteristic by YAG laser, and state monitor technology of pre-process of a laser welding system by signal waveform analysis from an AE sensor installed to materials was developed. The technology that signal waveform analysis of optical intensity a welding process was applied to about the system fault diagnosis technology next is expressed.The method of the quality control in the laser welding system has various techniques. It is necessary to manage not only in-process but also pre-process and post-process for improvement of the welding quality. In this paper, the fault condition sensing technique is proposed by the waveform analysis of the physical quantity in the welding process. The waveform analysis such as running average process, differential characteristics, integral characteristics and time subtraction of data are particularly effective for monitoring a laser welding system. Application of the technique to the half penetration welding with the Nd:YAG laser for thin stainless steel sheets is discussed. At first an installation state to a jig of materials end paid its attention to a phenomenon to influence a welding processing characteristic by YAG laser, and state monitor technology of pre-process of a laser welding system by signal waveform analysis from an AE sensor installed to materials was developed. The technology that signal w...