Selective power supply for travelling wire EDM apparatus

摘要

In a travelling wire EDM apparatus the thermal stresses of the electrode wire are substantially reduced by detecting the position of the triggering electrical discharges preceding the machining electrical discharges, and by controlling the supply of the machining electrical discharge current at one end of the machining zone, at the other end of the machining zone or at both ends of the machining zone. When a machining electrical discharge is located between one end of the machining zone and a first reference position, the machining current is applied at that end. When the electrical discharge is located between the other end of the machining zone and a second reference position, machining current is supplied at that second end. When the electrical discharge is located between the two reference positions, the machining current is applied simultaneously at both ends of the machining zone.