FLASH WELDING DEVICE

PURPOSE:To reduce the size and weight of a device by bearing the reaction in the stage of upsetting by means of rest parts for detaining provided to contg. parts of clamping heads and recesses for engaging of clamping jigs which engage with the outside peripheral projecting parts of materials to be joined. CONSTITUTION:The clamping jigs 13 are respectively mounted to the materials 11, 12 to be joined by engaging the recesses 20 for engaging thereof with the outside peripheral projecting parts 19 of the materials 1, 2. The jigs 13 are then respectively mounted to the contg. parts 10 of the clamping heads 1, 2 and the root ends of the jigs 13 are pressed and detained to the rest parts 15 for detatining; thereafter, the materials are clamped and fixed between backing metals 8 and clamping arms 9. Flashes are emitted from the end faces of the materials 11, 12 when welding current is conducted thereto and an oil pressure is exerted thereto. A high and large-capacity oil pressure is supplied to a hydraulic cylinder in the stage of prescribed upsetting, then a clamping arm 1 is quickly propelled to upset quickly and powerfully the material 11 toward the stationary material 12, by which both materials are joined.