Mazda Motor Corporation

Yohei Shoji

Toshiyuki Gendou

Kenji Takase

Yukihiro Sugimoto

Katsuya Nishiguchi

Daisuke Nakazaki

Akira Nawahara

Yasuyuki Tanaka

In electric resistance welding for energizing a workpiece formed by superimposing plural metal plates, an energization resistance reduction amount between a pair of electrodes pressurizing the workpiece is detected at a specified time interval during each welding process under a specified welding condition, frequency distribution of the energization resistance reduction amount under the welding condition is calculated on the basis of data relating to the energization resistance reduction amount, the frequency distribution is fitted with a Gaussian function, and occurrence of an expulsion under the welding condition is determined on the basis of whether the fitting is statistically significant.

Expulsion detection method in electric resistance welding and apparatus therefor

In a frictional spot joining where plural metal members lapping over are jointed with a joining device comprising a rotating tool, a receiving tool disposed on a rotational axis of the rotating tool and a drive device to rotate and move the rotating tool in a pushing direction, a holding member is provided on a side of the receiving tool, which has a restriction portion to restrain a movement of the receiving tool in a direction perpendicular to the rotational axis, and the joining device is moved by a moving device such that the receiving tool is disposed at the restriction portion. Accordingly, the rotational runout of the rotating tool can be restrained effectively with a simple structure of a properly small-sized rotating tool and receiving tool.

Frictional spot joining method and frictional spot joining apparatus

In the third step of joining of the metal members, the pressing force of the rotational tool under rotation is maintained at the third pressing force that is smaller than the second pressing force until a specified period of time elapses after the tip of the pin portion of the rotational tool has reached the specified point that is at a distance from the joining face. Accordingly, the proper plastic flow of the metal member can be generated and thereby the joining strength with a sufficient period of time of agitation can be ensured, by maintaining a high temperature enough to soften the metal member and by preventing the rotational tool from coming into the metal member too deeply or from penetrating the metal member.

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Hiroshima, Japan

Yohei Shoji