| 摘要 |
PURPOSE:To eliminate explosion immediately before up-setting by measuring the welding voltage between the works to be welded at a pre-heating stage and by reducing the weld current or increasing the pressurizing force so that the voltage thereof does not exceed the set reference voltage. CONSTITUTION:A welding current I0 is conducted with holding a fixed pressurizing force by abutting the butt end faces of a work which are respectively fitted to a fixed stand and mobile stand it is measured that the welding voltage V between works is raised according to the temp. rise of a heating part. The current I is then controlled so as to reduce gradually until it goes to I1 with controlling the arc ignition phase of a thyristor so that the voltage V does not exceed the reference voltage VS which is set up in advance. When the displacement D of the mobile stand reaches the value D1 to be set in advance, the current I1 is increased at a single stroke until I2 and simultaneously the pressurizing force as well is increased at a stroke and an upset stage is started. The explosive scattering immediately before the up-setting is eliminated accordingly and good welding part is obtd. |
