| 摘要 |
PURPOSE:To prevent the wear of an electrode by restraining the generation of a scattering body and to prevent the generation of a expulsion by removing the galvanized film of a spotting point part by a pressure electrification and forming a nugget with the pressure electrification again of this removed part. CONSTITUTION:Two sheets of galvanized steel sheets 5 are subjected to a pinching pressing by their overlapping by the electrode 4b fitted to the gun arm 4a of a pair of spot guns. An electrification is performed with the electrifying command placed from a timer contactor simultaneously with the pressing. The current of this time is adjusted so as to heat the galvanized steel sheet 5 at >= the temp. vaporizing the zinc plated film 5a formed on both faces of the galvanized steel sheet 5 and <= the temp. no nugget is formed. The pressing is then released simultaneously with cutting off the current after the electrification for a fixed time and the vaporized gas of the plated metal of a face mating part is released to the external part, then the plated film 5c of the electrification part of the galvanized steel sheet 5 is removed and the surface of the steel plate 5b is exposed. The same part with the 1st pressing point of two sheets of overlapped galvanized steel sheets 5 is then electrified by pressing it again, a nugget 11 is formed and the welding is completed. |
