| 摘要 |
A method and apparatus for threading the electrode wire of a travelling wire EDM apparatus through an aperture in a workpiece. Prior to threading the wire through the aperture in the workpiece, the wire is continuously annealed and straightened and is passed through a nozzle to which fluid under pressure is supplied for forming a jet stream at the outlet of the nozzle. Prior to a threading or rethreading operation the wire, which is continuously fed by pulling by a wire conveyor mechanism, is cut off proximate to the outlet of the nozzle. The jet stream is aimed at the aperture in the workpiece and the end of the wire is fed through the aperture, while being maintained coaxially by the jet stream. The consecutive steps for feeding the end of the wire through the aperture in the workpiece are effected in sequence for first threading the wire through a pre-drilled starting hole in the workpiece or for rethreading the wire through a cut in the workpiece after accidental rupture of the wire during a cutting operation. |
