Toyota Jidosha Kabushiki Kaisha

Kabushiki Kaisha Toyota Chuo Kenkyusho

Yasuhiro Ishii

Tsunaji Kitayama

Keisuke Uchida

Hisaaki Takao

Masahiro Nishio

Hideki Teshima

Goro Watanabe

Yuji Kawazoe

Yasumoto Sato

Exemplary embodiments provide a resistance welding method capable of stabilizing quality or improving efficiency of resistance welding such as spot welding. This resistance welding method comprises a calculating step of calculating resistance ratio X of a second electric resistance value Rof workpieces to be joined in residual heat after Joule heating stops to a first electric resistance value Rof the workpieces immediately before the Joule heating stops or vice versa (R/Ror R/R); a determining step of determining whether the resistance ratio X is equal to or greater than a threshold value Xn, and a reheating step of carrying out the Joule heating again when the resistance ratio X is smaller than the threshold value Xn. Thereby at least part of a welding portion is melted and solidified to reliably form a nugget, and a stably resistance-welded member can be provided.

Resistance welding method, resistance welder, and method and device for evaluating resistance welding

A difference processing circuit receives input of welding images taken by a CCD camera in real time and then differentiates power monitoring images recorded in a memory from welding images to obtain difference processing reflected light images. Due to the difference processing performed by a difference processing circuit, foreign matter images included in welding images and power monitoring images are eliminated and the difference processing reflected light images that are obtained do not include any foreign matter images. A quality judgment device uses the difference processing reflected light images obtained by a difference processing circuit and conducts a quality judgment. As described above, since difference processing reflected light images do not include any foreign matter images, a quality judgment device does not receive any influence from the foreign matter that is adhered to the protective glass and can conduct an excellent evaluation of the welding quality.

Laser welding quality evaluation method and apparatus

Growing community of inventors

Nisshin, Japan

Yasuhiro Ishii