Honda Motor Co., Ltd.

Kabushiki Kaisha Sg

Yasuyuki Mizutani

Wataru Ichikawa

Yuji Matsuki

Seiji Hirohashi

Masaru Ohara

Toshiharu Nakagima

Terry Sullivan

Yuji Taya

Shingi Hoshino

A decrease amount in plate thickness at a spot weld is detected at a predetermined time period when application of pressure is still maintained after termination of power supply to electrodes for spot welding. The decrease amount is correlated with the magnitude of diameter of nugget formed by spot welding, e.g., a larger diameter of nugget signifies a stronger the joint, and therefore, the quality of joint at the spot weld can be examined on the basis of the detected decrease amount. Since a value obtained by integrating plate thickness detection data of the spot weld during the predetermined time period is correlated, as the decrease amount is, with the magnitude of the diameter of a nugget, the quality of the joint may also be examined on the basis of this integrated value. There is provided, in a spot welding machine, a detector for detecting a stroke position of a cylinder for pressing electrodes or a detector for detecting a position of displacement of a tip portion of an arm interlocked with the movement of the electrodes and the distance between the electrodes, i.e., plate thickness, can be indirectly detected by the detector without adversely affecting efficiency of the spot welding work.

Method for checking a spot welded portion and spot welding machine

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Suzuka, Japan

Yasuyuki Mizutani