| 摘要 |
PROBLEM TO BE SOLVED: To weld a plate assembly with high strength by making welding current distribution impressed to the plate assembly uniform and improving the quality of nuggets which are formed on the mutual galvanized steel sheets by removing effectively alloy layers which are formed in the center parts of the tip surfaces of electrode chips in accordance with the progress of electric resistance welding.SOLUTION: When the number of spots of the electric resistance welding with a pair of electrode chips 9, 11 reaches 10-100, the tip portions of the electrode chips are rushed into the fairing chambers of an electrode chip reproducing tool which has a tip surface fairing projecting parts which are parallel to the tip surfaces of the electrode chips on a plurality of lines of outer circumferential surface fairing projecting parts which are formed over the bottom from the concave inner peripheral surfaces of the fairing chambers in accordance with the tip portions of the electrode chips and is rotated. By the rolling circumferential surface fairing projecting parts and the tip surface fairing projecting parts, the tip portions of the electrode chips which are expanded and deformed by pressurization during electric resistance welding to the tip side, the tip portions are faired into a normal outer circumferential shape and alloy layers, on the tip surface of which films are formed by the tip surface fairing projection parts, the alloy layers being mainly composed of copper, zinc and iron are removed with only a part left behind. |
