JPS5550986A - Resistance welding method - Google Patents

Abstract

PURPOSE: To prevent the annihilation, discoloration and dent of hairlines by performing pressure current supply in the state where only the periphery of the mutual contact pressure parts of the materials to be welded are supported by pressure electrodes.

CONSTITUTION: A protrusion 14 is provided to the material 1 to be welded which does not require aesthetic appearance and with said protrusion being faced to the side of the material 2 to be welded where there are no hairlines, the materials are held between electrode chips 3, 4. The leading end of the electrode chip 4 has a recess 5 encircled by the conical inside wall 8 of the cover 12 protruding from this and the bottom face 2' of the material to be welded. The recess 5 is disposed right under the weld zone 15 and the pressing forces of both electrode chips are received by the rigidity of the material 2 to be welded per se. Hence, the weld zone 15 deforms and when current is supplied next, the contact parts of the materials to be welded weld and the foregoing deformation returns as much as this. When the current supply is stopped, the face 2' returns flat owing to the thermal shrinkage of the nugget 10 and the pressed part 9 detaches from the weld zone 14. Since the pressure receiving area is wide, the hairlines are not crushed. On the other hand, when gas is flowed from inlet 7 to the recess 5, the weld zone is surely covered with the gas, whereby its discoloration is prevented.

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