Investigation of Upset Process and Development of Control Method for Interface Quality of Welds

Welding Phenomena and Process Control in the Flash Welding of steel sheets (Report 3)

Abstract

Initial stage of upset was investigated. The welding machine for experiment was designed so that platen movement for upsetting can be initiated at any desired voltage phase of AC power source. The voltage phase of AC power source at the instant of platen movement for upsetting, named "upsetting point", showed significant influence on weld interface quality. The quality was best at the phase round 90 degree and worst at round 0 (or 180) degree. Good relasionship was observed between the phase and the quality. The influence of upsetting point control on weld interface quality was proved to be greater than that of duration of upset current by conventional current density, i.e. less than 80 A per square millimeter.