Taper cutting control method and control system in wire-cut electric discharge machine

• US 4,843,203 A
• Filed: 06/14/1988
• Issued: 06/27/1989
• Est. Priority Date: 10/08/1980
• Status: Expired due to Fees

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Kinoshita, Mitsuo, Gamo, Gotaro
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): Evans, Geoffrey S.
• Application Number:
  US07/208,859
• Time in Patent Office: 378 Days
• Field of Search: 219/69 W, 219/69 M, 219/69 C, 204/206
• US Class Current: 219/69.12
• CPC Class Codes: B23H 7/065 Electric circuits specially adapted therefor

Abstract

To permit machining of a workpiece into a highly accurate tapered configuration, a wire-cutting EDM including a numerical controller that reads programmed shape data is utilized. To precisely taper the workpiece, it is necessary to move the upper and lower guides of the wire so that they start and stop moving simultaneously. From the programmed shape data, the respective speeds of the upper and lower guides are computed. The upper guid is interpolated by the upper guide speed, and the lower guide is interpolated by the lower guide speed so that the guides can start and stop moving simultaneously.

Claims

1. A method of controlling a wire-cutting electric discharge machine for moving a workpiece relative to a wire electrode and moving upper and lower guides which support the wire electrode, relative to each other to machine a workpiece to generate a twisted taper surface according to a machining command, said method comprising the steps of:

(a) computing offsets of the upper and lower guides from a machining path on a prescribed surface of the workpiece from a machining command applied from a numerical control system;

(b) computing distances Lu and Ld of movement of the upper and lower guides from said computed offsets and a machining distance Lw along the machining path;

(c) computing ratios Lu/Lw and Ld/Lw of said distances Lu and Ld of movement of the upper and lower guides to said machining distance Lw;

(d) computing speeds Fu and Fd of movement of the upper and lower guides from a machining speed Fw on the prescribed surface of the workpiece and said ratios Lu/Lw and Ld/Lw according to the equations;

space="preserve" listing-type="equation">Fu=(Lu/Lw)×

Fw,

space="preserve" listing-type="equation">Fd=(Ld/Lw)×

Fw;

(e) interpolating the upper guide with said speed Fu of the movement of the upper guide, interpolating the lower guide with said speed Fd of movement of the lower guide, and simultaneously starting the moving of the upper and lower guides; and

(f) performing steps (a) through (e) a plurality of times.

2. A system for controlling a wire-cutting electric discharge machine for moving a workpiece relative to a wire electrode and moving upper and lower guides which support the wire electrode, relative to each other, to machine a workpiece to generate a twisted taper surface according to a machining command, said system comprising:

(a) means for computing distances Lu and Ld of the upper and lower guides, respectively, and a machining distance Lw on a commanded prescribed surface of the workpiece from positional information contained in the machining command;

(b) means for computing ratios Lu/Lw and Ld/Lw of said distances Lu and Ld of movement of the upper and lower guides to the machining distance Lw;

(c) means for computing speeds Fu and Fd of movement of the upper and lower guides, respectively, by multiplying a relative speed Fw of movement between the workpiece and the wire electrode on the prescribed surface by said ratios Lu/Lw and Ld/Lw;

(d) interpolating means for generating interpolation pulses to drive said upper and lower guides based on the speeds Fu and Fd of movement of the upper and lower guides and the positional information contained in the machining command; and

(e) upper and lower guide driving means driveable by the interpolation pulses generated by said interpolating means for simultaneously starting said upper and lower guides and simultaneously stopping said upper and lower guides.

3. A system according to claim 2, wherein said interpolating means comprises circular interpolators.

4. A system according to claim 2, wherein said interpolating means comprises linear interpolators.