Wire electric discharge machining method

• US 5,859,401 A
• Filed: 04/23/1997
• Issued: 01/12/1999
• Est. Priority Date: 08/23/1995
• Status: Expired due to Term

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Kita, Yuki, Kajitori, Toyotada
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US08/817,867
• Time in Patent Office: 629 Days
• Field of Search: 219/69.12
• US Class Current: 219/69.12
• CPC Class Codes: B23H 7/02 Wire-cutting
• CPC Class Codes: B23H 7/06 Control of the travel curve of the relative movement between electrode and workpiece
• CPC Class Codes: B23H 7/10 Supporting, winding or electrical connection of wire-electrode
• CPC Class Codes: B23H 7/102 Automatic wire threading

Abstract

A wire electric discharge machining method capable of performing a first machining and also a second cut-off machining based on a single machining program. A program for defining machining paths for cutting off individual male forms A1-A3 is inputted and a reserve amount α and a backward amount β are set. In the first machining, the electric discharge machining is stopped with the reserve amount α left, and this stop position is stored. In the second cutting machining, an automatic wire connection is performed at a wire connecting position turned back by the backward amount β from the stop position along the machined groove which is formed in the first machining, and then the male forms A are successively cut off by performing the discharge machining from the wire connecting position. A wire discharge machine has an annealing/fusing device for annealing and fusing the wire with heat generated by an electric current flow in the wire. Since the wire is made straight by the annealing and a cut end thereof is made hemispheric, the wire can be easily inserted into the machined groove.

Claims

1. A wire electric discharge machining method for cutting a plurality of male forms off a workpiece using a wire electric discharge machine having an annealing/fusing device for annealing a wire into a straight shape upstream of an upper wire guide in a wire path and fusing the wire near the upper wire guide, and an automatic wire connecting device for automatically connecting the wire by restricting the wire by a machining fluid flow from a nozzle of the upper guide, said method comprising the steps of:

(a) inputting a machining program defining a plurality of machining paths corresponding to the respective male forms and setting a reserve amount for a first electric discharge machining and a backward amount for a second discharge machining;

(b) performing the first discharge machining by (b1) automatically connecting the wire through a machining-start hole in the first machining path by said automatic wire connecting device, to perform an electric discharge machining for shaping along the first machining path based on said machining program, (b2) stopping the electric discharge machining at a stop position with said reserve amount left along the first machining path, to anneal and fuse the wire by said annealing/fusing device, and (b3) performing and stopping the electric discharge machining along successive machining paths in the same manner as said steps (b1) and (b2); and

(c) performing the second discharge machining by (c1) automatically connecting the wire at a wire connecting position turned back by said backward amount from said stop position in said step (b2) along a machined groove formed in the electric discharge machining of said step (b1), (c2) cutting off a first male form by performing the electric discharge machining from said wire connecting position along the first machining path based on said machining program, (c3) annealing and fusing the wire by said the annealing/fusing device, and (c4) cutting off said plurality of male forms successively in the same manner as said steps (c1), (c2) and (c3).

2. A wire electric discharge machining method according to claim 1, wherein said annealing of the wire by said annealing/fusing device is performed by flowing an electric current in the wire through two wire fusing electrodes disposed on a straight line with a predetermined distance therebetween in the wire path upstream of said upper wire guide, and said fusing of the wire is performed in the vicinity of one of said wire fusing electrodes, which is disposed near the upper wire guide.