Wire electrical discharge machine and control method

Patent metadata

Field	Value
Publication number	US-11813684-B2
Application number	US-202016942129-A
Country	US
Kind code	B2
Filing date	Jul 29, 2020
Priority date	Aug 2, 2019
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

A wire electrical discharge machine includes: a detection unit configured to detect a contact state in which the wire electrode contacts the workpiece, and a contact release state in which the wire electrode that is in the contact state is separated from the workpiece; a vibration unit configured to, if the contact state is detected during the machining of the workpiece, stop relative movement of the wire electrode and vibrate the wire electrode about a stop position at which the relative movement of the wire electrode has been stopped; and a relative movement control unit configured to resume relative movement of the wire electrode if the contact release state is detected until a predetermined time elapses from when the contact state has been detected or until the number of times that the wire electrode is vibrated reaches a predetermined number of times.

First claim

What is claimed is:

1. A wire electrical discharge machine for machining a workpiece by generating electrical discharge at an electrode gap formed between the workpiece and a wire electrode while moving the wire electrode relative to the workpiece, comprising:
a control unit including a processor; and
a storage unit, the storage unit storing instructions to cause the processor to control:
a detection unit for detecting a contact state in which the wire electrode contacts the workpiece, and a contact release state in which the wire electrode that is in the contact state is separated from the workpiece;
a vibration unit for, if the contact state is detected during machining of the workpiece, stopping relative lateral movement of the wire electrode with respect to a Y-axis direction and an X-axis direction of the workpiece and vibrate the wire electrode about a stop position at which the relative lateral movement of the wire electrode has been stopped; and
a relative movement control unit for resuming relative lateral movement of the wire electrode if the contact release state is detected until a predetermined time elapses from when the contact state has been detected or until a number of times that the wire electrode is vibrated reaches a predetermined number of times.

2. The wire electrical discharge machine according to claim 1 , wherein the storage unit further stores instructions to cause the processor to control a determination unit for determining whether or not the wire electrode will contact the workpiece when the wire electrode moves backward from the stop position along a machining groove formed in the workpiece,
wherein the relative movement control unit relatively moves the wire electrode so as to move backward by a set distance from the stop position along the machining groove if the contact release state is not detected until the predetermined time elapses from when the contact state has been detected or until the number of times that the wire electrode is vibrated reaches the predetermined number of times, and if it is determined that the wire electrode will not contact the workpiece when the wire electrode moves backward from the stop position.

3. The wire electrical discharge machine according to claim 2 , wherein the determination unit determines that the wire electrode moved backward from the stop position will contact the workpiece if a difference obtained by subtracting, from a groove width of the machining groove at the stop position, a groove width of the machining groove at a backward-moved position that is located the set distance away from the stop position is equal to or greater than a threshold, and determine that the wire electrode moved backward from the stop position will not contact the workpiece if the difference is less than the threshold.

4. The wire electrical discharge machine according to claim 2 , wherein the determination unit determines whether or not the wire electrode moved backward from the stop position will contact the workpiece, based on an image captured by a camera arranged so as to be oriented in a direction in which the wire electrode extends.

5. The wire electrical discharge machine according to claim 4 , wherein the determination unit determines whether or not the wire electrode moved backward from the stop position will contact the workpiece, based on the image of the workpiece being machined in a liquid, captured under a condition that at least a surface of the workpiece that faces the camera is not submerged in the liquid.

6. The wire electrical discharge machine according to claim 2 , wherein the storage unit further stores instructions to cause the processor to control a notification unit for giving notification of occurrence of abnormality if the contact release state is not detected until the predetermined time elapses from when the contact state has been detected or until the number of times that the wire electrode is vibrated reaches the predetermined number of times, and if it is determined that the wire electrode moved backward from the stop position will contact the workpiece.

7. A control method of a wire electrical discharge machine for machining a workpiece by generating electrical discharge at an electrode gap formed between the workpiece and a wire electrode while moving the wire electrode relative to the workpiece, comprising:
if a contact state in which the wire electrode contacts the workpiece during machining of the workpiece is detected, stopping relative lateral movement of the wire electrode with respect to a Y-axis direction and an X-axis direction of the workpiece and vibrating the wire electrode about a stop position at which the relative lateral movement of the wire electrode has been stopped; and,
resuming relative lateral movement of the wire electrode if a contact release state in which the wire electrode that is in the contact state is separated from the workpiece is detected until a predetermined time elapses from when the contact state has been detected or until a number of times that the wire electrode is vibrated reaches a predetermined number of times.

8. The control method according to claim 7 , further comprising determining whether or not the wire electrode will contact the workpiece when the wire electrode moves backward from the stop position along a machining groove formed in the workpiece; and
relatively moving the wire electrode so as to move backward by a set distance from the stop position along the machining groove if the contact release state is not detected until the predetermined time elapses from when the contact state has been detected or until the number of times that the wire electrode is vibrated reaches the predetermined number of times, and if it is determined that the wire electrode will not contact the workpiece when the wire electrode moves backward from the stop position.

9. The control method according to claim 8 , wherein the determining determines that the wire electrode moved backward from the stop position will contact the workpiece if a difference obtained by subtracting, from a groove width of the machining groove at the stop position, a groove width of the machining groove at a backward-moved position that is located the set distance away from the stop position is equal to or greater than a threshold, and determines that the wire electrode moved backward from the stop position will not contact the workpiece W if the difference is less than the threshold.

10. The control method according to claim 8 , wherein the determining determines whether or not the wire electrode moved backward from the stop position will contact the workpiece, based on an image captured by a camera arranged so as to be oriented in a direction in which the wire electrode extends.

11. The control method according to claim 10 , wherein the determining determines whether or not the wire electrode moved backward from the stop position will contact the workpiece, based on the image of the workpiece being machined in a liquid, captured under a condition that at least a surface of the workpiece that faces the camera is not submerged in the liquid.

12. The control method according to claim 8 , further comprising giving notification of occurrence of abnormality if the contact release state is not detected until the predetermined time elapses from when the contact state has been detected or until the number of times that the wire electrode is vibrated reaches the predetermined number of times, and if it is determined that the wire electrode moved backward from the stop position will contact the workpiece.

13. The wire electrical discharge machine according to claim 1 , wherein the detec

Assignees

• Fanuc Corp

Inventors

• Yamaoka Masahide

Classifications

• B23H1/024 Primary

  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 title

• B23H7/28

  Moving electrode in a plane normal to the feed direction, e.g. orbiting · CPC title

• B23K9/0953

  using computing means · CPC title

• B23K9/0956

  using sensing means, e.g. optical · CPC title

• B23K9/30

  Vibrating holders for electrodes (B23K9/022 takes precedence) · CPC title