WIRE ELECTRIC DISCHARGE MACHINING DEVICE AND METHOD

• US 20150231716A1
• Filed: 12/10/2012
• Published: 08/20/2015
• Est. Priority Date: 12/09/2011
• Status: Active Grant

• Current Assignee: Sodick Company Limited (Plustech, Inc.)
• Original Assignee: Sodick Company Limited (Plustech, Inc.)
• Inventors: Yamazaki, Kiyoyuki, Matsui, Tatsuo
• Granted Patent: US 10,118,239 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23H 1/024 Detection of, and response to, abnormal gap conditions, e.g. short circuits preventing short circuits or other abnormal discharges by altering machining parameters using adaptive control B23H7/16
• CPC Class Codes: B23H 7/02 Wire-cutting
• CPC Class Codes: B23H 7/10 Supporting, winding or electrical connection of wire-electrode
• CPC Class Codes: B23H 7/104 Wire tension control
• CPC Class Codes: B23H 7/16 for preventing short circuits or other abnormal discharges by altering machining parameters using adaptive control
• CPC Class Codes: B23H 7/26 Apparatus for moving or positioning electrode relatively to workpiece; Mounting of electrode

Abstract

Provided is a wire electric discharge machining device and method capable of reliably terminating a short circuit between a wire electrode and a workpiece. The invention relates to a wire electric discharge machining device that starts machining of a workpiece (3) by generating an electric discharge in a machining gap formed between the workpiece and a wire electrode (2) threaded through a start hole (4) in the workpiece. The wire electric discharge machining device includes: a tension control device (56) that controls tension of the wire electrode so as to maintain the tension at a set value; a short circuit detector (57) that detects a short circuit between the wire electrode and the workpiece; and a short circuit termination system that reduces the tension of the wire electrode and vibrates the wire electrode in order to terminate a short circuit when the short circuit detector has detected the short circuit.

Claims

1. A wire electric discharge machining device that starts machining of a workpiece by generating an electric discharge in a machining gap formed between the workpiece and a wire electrode threaded through a start hole in the workpiece, the wire electric discharge machining device comprising:

a tension control device controlling tension of the wire electrode to be maintained at a set value;

a short circuit detector detecting a short circuit between the wire electrode and the workpiece; and

a short circuit termination system reducing the tension of the wire electrode and vibrating the wire electrode to terminate the short circuit when the short circuit detector has detected the short circuit.

2. The wire electric discharge machining device of claim 1, wherein the short circuit termination system reduces the set value of the tension when the short circuit detector has detected the short circuit.

3. The wire electric discharge machining device of claim 1, wherein the short circuit termination system reduces the set value of the tension to 10 to 50% when the short circuit detector has detected the short circuit.

4. The wire electric discharge machining device of claim 1, wherein the short circuit termination system comprises a vibration device jetting a high pressure dielectric liquid to the wire electrode to vibrate the wire electrode.

5. The wire electric discharge machining device of claim 1, wherein the short circuit termination system comprises a vertical motion device slightly vertically moving the wire electrode by compressed air.

6. The wire electric discharge machining device of claim 5, wherein the vertical motion device supplies compressed air in a manner to cross the wire electrode to vibrate the wire electrode transversely.

7. The wire electric discharge machining device of claim 5, wherein the vertical motion device comprises a wire guide having a guide hole through which the wire electrode passes, and the wire guide is movable upwardly by the compressed air.

8. The wire electric discharge machining device of claim 1, wherein the tension control device generates a tension command based on a detected value of the tension of the wire electrode and a gain, and the short circuit termination system reduces the gain when the short circuit detector has detected the short circuit.

9. The wire electric discharge machining device of claim 1, wherein the short circuit termination system reduces a running speed of the wire electrode when the short circuit detector has detected the short circuit.

10. A wire electric discharge machining method that starts machining of a workpiece by generating an electric discharge in a machining gap formed between a work electrode and the workpiece, the wire electric discharge machining method comprising:

threading the wire electrode through a start hole in the workpiece;

running the wire electrode by giving a predetermined tension to the wire electrode;

applying a voltage between the wire electrode and the workpiece to generate the electric discharge in the machining gap;

detecting a short circuit between the wire electrode and the workpiece; and

reducing the tension of the wire electrode and vibrating the wire electrode to terminate the short circuit.