Wire electric discharge machine having corner shape correcting function

• US 10,307,847 B2
• Filed: 11/12/2015
• Issued: 06/04/2019
• Est. Priority Date: 11/19/2014
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Hasegawa, Yasuo
• Primary Examiner(s): Hoang, Tu B
• Assistant Examiner(s): Duniver, Diallo I
• Application Number:
  US14/938,851
• Publication Number:
  US 20160136745A1
• Time in Patent Office: 1,300 Days
• Field of Search: 219 6912, 219 6911- 6914
• CPC Class Codes: B23H 1/02 Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges
• CPC Class Codes: B23H 7/065 Electric circuits specially adapted therefor
• CPC Class Codes: B23H 7/08 Wire electrodes
• CPC Class Codes: B23H 7/20 for programme-control, e.g. adaptive programme-control systems in general G05B19/00
• CPC Class Codes: B23H 7/26 Apparatus for moving or positioning electrode relatively to workpiece; Mounting of electrode
• CPC Class Codes: G05B 2219/45043 EDM machine, wire cutting

Abstract

A wire electric discharge machine has a function of performing correction of corner shapes independently on an upper surface and a lower surface of workpiece. On the basis of the positions of upper and lower wire guides and the position and the thickness of the workpiece, the wire electric discharge machine calculates, on the upper and lower surfaces of the workpiece, a shape correction amount in a state in which there is a space between the upper nozzle and the upper surface of the workpiece and also in which there is a space between the lower nozzle and the lower surface of the workpiece, from a correction amount at the time when nozzles of the upper and lower wire guides are closely attached to the upper and lower surfaces of the workpiece. The wire electric discharge machine performs shape correction according to the calculated shape correction amount.

Claims

1. A wire electric discharge machine, comprising:

a machining tank;

a table configured to support a workpiece and disposed in the machining tank;

an upper wire guide including an upper nozzle;

a lower wire guide including a lower nozzle;

a wire electrode stretched between the upper and lower wire guides;

a first group of motors configured to move the upper and lower wire guides;

a second group of motors configured to move the table;

a pump configured to jet machining liquid via the upper and lower nozzles to the workpiece on the table in the machining tank; and

a controller connected to the first and second groups of motors and the pump by power and signal lines to obtain positions of the upper and lower wire guides and a position of the table,

wherein the controller includes

a processor configured to,

control the first group of motors to move the upper and lower wire guides to cause the wire electrode to be moved with respect to the workpiece, or control the second group of motors to move the table to cause the workpiece to be moved with respect to the wire electrode, on the basis of a machining program in order to perform electric discharge machining of the workpiece by the wire electrode in the machining tank, wherein a shift is caused by wire bending of the wire electrode in a direction opposite to a movement direction of the wire electrode with respect to the workpiece due to machining liquid pressure and a discharge repulsive force generated during the electric discharge machining; and

a memory configured to

store, as a reference position, (i) positions of the upper and lower wire guides in a workpiece thickness direction with respect to workpiece upper and lower surfaces of the workpiece and (ii) a thickness of the workpiece, in a state in which the upper and lower wire guides respectively approach the workpiece upper and lower surfaces, and

store correction amounts for correcting shift amounts between (a) wire guide coordinate positions on a machining program route in the reference position and (b) actual machining positions on the workpiece upper and lower surfaces,

wherein

the processor is configured to

set values corresponding to positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, and a value corresponding to the thickness of the workpiece,

calculate correction amounts, on the basis of the stored reference position and the stored correction amounts, for correcting the respective shift amounts in the set values corresponding to the positions in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece,

correct positions of the upper and lower wire guides independently of each other, on the basis of the calculated correction amounts, and

cause the wire electrode to move with respect to the workpiece according to the corrected positions of the upper and lower wire guides in a movement command of the upper and lower wire guides with respect to the table commanded by the machining program.

2. A wire electric discharge machine, comprising:

a machining tank;

a table configured to support a workpiece and disposed in the machining tank;

an upper wire guide including an upper nozzle;

a lower wire guide including a lower nozzle;

a wire electrode stretched between the upper and lower wire guides;

a first group of motors configured to move the upper and lower wire guides;

a second group of motors configured to move the table;

a pump configured to jet machining liquid via the upper and lower nozzles to the workpiece on the table in the machining tank; and

a controller connected to the first and second groups of motors and the pump by power and signal lines to obtain positions of the upper and lower wire guides and a position of the table,

wherein the controller includes

a processor configured to,

control the first group of motors to move the upper and lower wire guides to cause the wire electrode to be moved with respect to the workpiece, or control the second group of motors to move the table to cause the workpiece to be moved with respect to the wire electrode, on the basis of a machining program in order to perform electric discharge machining of the workpiece by the wire electrode in the machining tank, wherein a shift is caused by wire bending of the wire electrode in a direction opposite to a movement direction of the wire electrode with respect to the workpiece due to machining liquid pressure and a discharge repulsive force generated during the electric discharge machining; and

a memory configured to

store, as reference positions, (i) sets of positions of the upper and lower wire guides in a workpiece thickness direction with respect to workpiece upper and lower surfaces of the workpiece and (ii) a thickness of the workpiece; and

store correction amounts for correcting shift amounts between (a) wire guide coordinate positions on a machining program route in the reference positions and (b) actual machining positions on the workpiece upper and lower surfaces, wherein

the processor is configured to

set values corresponding to positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, and a value corresponding to the thickness of the workpiece,

select a plurality of sets of the positions close to the set values corresponding to the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece, from the stored sets of the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the stored thickness of the workpiece,

calculate correction amounts, on the basis of the selected plurality of sets of reference positions and the stored correction amounts, for correcting the respective shift amounts in the set values corresponding to the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece,

correct positions of the upper and lower wire guides independently of each other, on the basis of the calculated correction amounts, and

cause the wire electrode to move with respect to the workpiece according to the corrected positions of the upper and lower wire guides in a movement command of the upper and lower wire guides with respect to the table commanded by the machining program.

3. A wire electric discharge machine, comprising:

a machining tank;

a table configured to support a workpiece and disposed in the machining tank;

an upper wire guide including an upper nozzle;

a lower wire guide including a lower nozzle;

a wire electrode stretched between the upper and lower wire guides;

a first group of motors configured to move the upper and lower wire guides;

a second group of motors configured to move the table;

a pump configured to jet machining liquid via the upper and lower nozzles to the workpiece on the table in the machining tank; and

a controller connected to the first and second groups of motors and the pump by power and signal lines to obtain positions of the upper and lower wire guides and a position of the table,

wherein the controller includes

a processor configured to,

control the first group of motors to move the upper and lower wire guides to cause the wire electrode to be moved with respect to the workpiece, or control the second group of motors to move the table to cause the workpiece to be moved with respect to the wire electrode, on the basis of a machining program in order to perform electric discharge machining of the workpiece by the wire electrode in the machining tank, wherein a shift is caused by wire bending of the wire electrode in a direction opposite to a movement direction of the wire electrode with respect to the workpiece due to machining liquid pressure and a discharge repulsive force generated during the electric discharge machining; and

a memory configured to

store, as reference positions, (i) sets of positions of the upper and lower wire guides in workpiece thickness direction with respect to workpiece upper and lower surfaces of the workpiece and (ii) a thickness of the workpiece; and

store correction amounts for correcting shift amounts between (a) wire guide coordinate positions on a machining program route in the reference positions and (b) actual machining positions on the workpiece upper and lower surfaces,

wherein

the processor is configured to

set values corresponding to the sets of positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, and a value corresponding to the thickness of the workpiece,

invoke correction amounts, from the stored reference positions and the stored correction amounts, for correcting the respective shift amounts in the set values corresponding to the sets of positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece,

correct positions of the upper and lower wire guides independently of each other, on the basis of the invoked correction amounts, and

cause the wire electrode to move with respect to the workpiece according to the corrected positions of the upper and lower wire guides in a movement command of the upper and lower wire guides with respect to the table commanded by the machining program.

4. A wire electric discharge machine, comprising:

a machining tank;

a table configured to support a workpiece and disposed in the machining tank;

an upper wire guide including an upper nozzle;

a lower wire guide including a lower nozzle;

a wire electrode stretched between the upper and lower wire guides;

a first group of motors configured to move the upper and lower wire guides;

a second group of motors configured to move the table;

a pump configured to jet machining liquid via the upper and lower nozzles to the workpiece on the table in the machining tank; and

a controller connected to the first and second groups of motors and the pump by power and signal lines to obtain positions of the upper and lower wire guides and a position of the table,

wherein the controller includes

a processor configured to,

control the first group of motors to move the upper and lower wire guides to cause the wire electrode to be moved with respect to the workpiece, or control the second group of motors to move the table to cause the workpiece to be moved with respect to the wire electrode, on the basis of a machining program in order to perform electric discharge machining of the workpiece by the wire electrode in the machining tank, wherein a shift is caused by wire bending of the wire electrode in a direction opposite to a movement direction of the wire electrode with respect to the workpiece due to machining liquid pressure and a discharge repulsive force generated during the electric discharge machining; and

a memory configured to

store, as a reference position, (i) positions of the upper and lower wire guides in a workpiece thickness direction with respect to workpiece upper and lower surfaces of the workpiece and (ii) a thickness of the workpiece, in a state in which the upper and lower wire guides respectively approach the workpiece upper and lower surfaces; and

store shift amounts between (a) wire guide coordinate positions on a machining program route in the reference position and (b) actual machining positions on the workpiece upper and lower surfaces,

wherein

the processor is configured to

calculate shift correction amounts from the stored shift amounts,

set values corresponding to positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, and a value corresponding to the thickness of the workpiece,

calculate correction amounts, on the basis of the stored reference position and the calculated shift correction amounts, for correcting the respective shift amounts in the set values corresponding to the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece,

correct positions of the upper and lower wire guides independently of each other, on the basis of the calculated correction amounts, and

cause the wire electrode to move with respect to the workpiece according to the corrected positions of the upper and lower wire guides in a movement command of the upper and lower wire guides with respect to the table commanded by the machining program.

5. A wire electric discharge machine, comprising:

a machining tank;

a table configured to support a workpiece and disposed in the machining tank;

an upper wire guide including an upper nozzle;

a lower wire guide including a lower nozzle;

a wire electrode stretched between the upper and lower wire guides;

a first group of motors configured to move the upper and lower wire guides;

a second group of motors configured to move the table;

a pump configured to jet machining liquid via the upper and lower nozzles to the workpiece on the table in the machining tank; and

a controller connected to the first and second groups of motors and the pump by power and signal lines to obtain positions of the upper and lower wire guides and a position of the table,

wherein the controller includes

a processor configured to,

control the first group of motors to move the upper and lower wire guides to cause the wire electrode to be moved with respect to the workpiece, or control the second group of motors to move the table to cause the workpiece to be moved with respect to the wire electrode, on the basis of a machining program in order to perform electric discharge machining of the workpiece by the wire electrode in the machining tank, wherein a shift is caused by wire bending of the wire electrode in a direction opposite to a movement direction of the wire electrode with respect to the workpiece due to machining liquid pressure and a discharge repulsive force generated during the electric discharge machining; and

a memory configured to

store, as reference positions, (i) sets of positions of the upper and lower wire guides in a workpiece thickness direction with respect to workpiece upper and lower surfaces of the workpiece and (ii) a thickness of the workpiece; and

store shift amounts between (a) wire guide coordinate positions on a machining program route in a plurality of the reference positions and (b) actual machining positions on the workpiece upper and lower surfaces,

wherein

the processor is configured to

calculate shift correction amounts from the stored shift amounts,

set values corresponding to positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, and a value corresponding to the thickness of the workpiece,

select a plurality of sets of the positions of the upper and lower wire guides close to the set values corresponding to the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece, from the stored sets of the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the stored thickness of the workpiece,

calculate correction amounts, on the basis of the selected plurality of sets of the positions and the calculated shift correction amounts, for correcting the respective shift amounts in the set values corresponding to the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece,

correct positions of the upper and lower wire guides independently of each other, on the basis of the invoked correction amounts, and

cause the wire electrode to move with respect to the workpiece according to the corrected positions of the upper and lower wire guides in a movement command of the upper and lower wire guides with respect to the table commanded by the machining program.

6. A wire electric discharge machine, comprising:

a machining tank;

a table configured to support a workpiece and disposed in the machining tank;

an upper wire guide including an upper nozzle;

a lower wire guide including a lower nozzle;

a wire electrode stretched between the upper and lower wire guides;

a first group of motors configured to move the upper and lower wire guides;

a second group of motors configured to move the table;

a pump configured to jet machining liquid via the upper and lower nozzles to the workpiece on the table in the machining tank; and

a controller connected to the first and second groups of motors and the pump by power and signal lines to obtain positions of the upper and lower wire guides and a position of the table,

wherein the controller includes

a processor configured to,

control the first group of motors to move the upper and lower wire guides to cause the wire electrode to be moved with respect to the workpiece, or control the second group of motors to move the table to cause the workpiece to be moved with respect to the wire electrode, on the basis of a machining program in order to perform electric discharge machining of the workpiece by the wire electrode in the machining tank, wherein a shift is caused by wire bending of the wire electrode in a direction opposite to a movement direction of the wire electrode with respect to the workpiece due to machining liquid pressure and a discharge repulsive force generated during the electric discharge machining; and

a memory configured to

store, as reference positions, (i) sets of positions of the upper and lower wire guides in workpiece thickness direction with respect to workpiece upper and lower surfaces of the workpiece and (ii) a thickness of the workpiece; and

store shift amounts between (a) wire guide coordinate positions on a machining program route in the reference positions and (b) actual machining positions on the workpiece upper and lower surfaces,

wherein

the processor is configured to

calculate shift correction amounts from the stored shift amounts,

set values corresponding to positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, and a value corresponding to the thickness of the workpiece,

invoke correction amounts, from the stored reference positions and the calculated shift correction amounts, for correcting the respective shift amounts in the set values corresponding to the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces and the set value corresponding to the thickness of the workpiece,

correct positions of the upper and lower wire guides independently of each other, on the basis of the invoked correction amounts, and

cause the wire electrode to move with respect to the workpiece according to the corrected positions of the upper and lower wire guides in a movement command of the upper and lower wire guides with respect to the table commanded by the machining program.

7. The wire electric discharge machine according to claim 1, wherein the memory is configured to store a plurality of sets of positions of the upper and lower wire guides and the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, instead of storing the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces.

8. The wire electric discharge machine according to claim 2, wherein the memory is configured to store a plurality of sets of positions of the upper and lower wire guides and the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, instead of storing the sets of positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces.

9. The wire electric discharge machine according to claim 3, wherein the memory is configured to store a plurality of sets of positions of the upper and lower wire guides and the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, instead of storing the sets of positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces.

10. The wire electric discharge machine according to claim 4, wherein the memory is configured to store a plurality of sets of positions of the upper and lower wire guides and the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, instead of storing the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces.

11. The wire electric discharge machine according to claim 5, wherein the memory is configured to store a plurality of sets of positions of the upper and lower wire guides and the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, instead of storing the sets of positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces.

12. The wire electric discharge machine according to claim 6, wherein the memory is configured to store a plurality of sets of positions of the upper and lower wire guides and the positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces, instead of storing the sets of positions of the upper and lower wire guides in the workpiece thickness direction with respect to the workpiece upper and lower surfaces.

13. The wire electric discharge machine according to claim 1, wherein when the upper wire guide is moved upward or downward in the workpiece thickness direction,

the processor is configured to, by acquiring a value of the movement of the upper wire guide in the workpiece thickness direction, calculate a distance from the upper wire guide to the lower wire guide in association with the position of the upper wire guide in the workpiece thickness direction, and the memory is configured to store the calculated distance.