Electric discharge machine

摘要

A wire or band electrode type electric discharge machine for machining hard metals by an electric spark generated between the metal workpiece and a wire electrode which is fed longitudinally to provide a fresh supply thereof while a prescribed relative motion is established between the workpiece and the wire electrode. The invention provides a clamping mechanism on the wire supply side of the workpiece for clamping the wire electrode if it breaks during operation, and a wire electrode feed mechanism for automatically guiding the broken end of the wire through the opening that has been machined in the workpiece. A wire electrode pull-up mechanism is provided on the other side of the workpiece for gripping and pulling up the wire electrode. If the electrode wire breaks during a machining operation, the clamping mechanism immediately clamps the wire electrode and prevents it from falling under its own weight. Thereafter the wire electrode feed mechanism draws the broken wire electrode away from the surface of the workpiece and then reinserts the broken end through the opening until the end of the wire emerges from the opposite side. The wire electrode pull-up mechanism the grips the end of the wire and pulls it to a new position to restore operation after it has been released by the clamping mechanism.