Device for detecting successful wire threading in electric discharge machines for working metal

摘要

Successful threading of a wire on an electric discharge machine is detected by a device including an isolation transformer with one terminal of its primary coil connected to a contact point on a wire guide downstream of the wire traction member (5) of the lower head (3). A DC to AC current converter feeds voltage to a the transformer output and an amplifier comparator receives an output signal from the transformer and communicates it to a microprocessor (8) which controls the wire threading device on the upper wire guide (2). The second terminal of the transformer primary directly or indirectly connects to the second contact point.