Wire electrical discharge machining device

• US 10,493,547 B2
• Filed: 04/14/2017
• Issued: 12/03/2019
• Est. Priority Date: 04/15/2016
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Yoda, Shinji, Furuta, Tomoyuki, Matsunaga, Tomoaki
• Primary Examiner(s): Jennison, Brian W
• Application Number:
  US15/488,194
• Publication Number:
  US 20170297126A1
• Time in Patent Office: 963 Days
• 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 1/022 for shaping the discharge pulse train B23H1/024 takes precedence
• 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 7/04 Apparatus for supplying current to working gap; Electric circuits specially adapted therefor

Abstract

Whether or not an inter-electrode voltage exceeds a voltage threshold is determined after a predetermined inter-electrode state determination period has passed since application of an induction voltage (inter-electrode voltage) to an inter-electrode gap. Thus, an inter-electrode gap amount between a wire electrode and a work is estimated. A pause time during which electrical discharge is not performed is changed according to an estimation result of the inter-electrode gap amount.

Claims

1. A wire electrical discharge machining device, comprising:

a discharge induction circuit configured to apply an induction voltage to an inter-electrode gap between an electrode and a work and configured to induce electrical discharge;

a main discharge circuit configured to apply a machining voltage to the inter-electrode gap and allow a machining current to flow therein,

wherein the wire electrical discharge machining device is configured to process the work by repeating a series of cycle including an operation and a pause of the discharge induction circuit and the main discharge circuit,

the cycle comprising an operation of the discharge induction circuit, a subsequent operation of the main discharge circuit, and a next subsequent pause time during which the discharge induction circuit and the main discharge circuit are not operated;

a first processor configured to output an application detection signal in response to an inter-electrode voltage exceeding a threshold, after a predetermined inter-electrode state determination period has passed since application of the induction voltage to the inter-electrode gap by the discharge induction circuit; and

a second processor configured to change at least one of the pause time and an operation time of the main discharge circuit according to whether or not the first processor outputs the application detection signal,

wherein, in response to the first processor not outputting the application detection signal after the inter-electrode state determination period has passed, the second processor is configured to decrease the pause time, compared to a case where the first processor outputs the application detection signal at a point of time at which the inter-electrode state determination period has ended.

2. The wire electrical discharge machining device according to claim 1, wherein, in response to the first processor not outputting the application detection signal after the inter-electrode state determination period has passed, the second processor is configured to increase the operation time of the main discharge circuit, compared to a case where the first processor outputs the application detection signal at a point of time at which the inter-electrode state determination period has passed.

3. The wire electrical discharge machining device according to claim 1, wherein the second processor is configured to change at least one of the pause time and the operation time of the main discharge circuit when finishing is performed.

4. A wire electrical discharge machining device, comprising:

a discharge induction circuit configured to apply an induction voltage to an inter-electrode gap between an electrode and a work and configured to induce electrical discharge;

a main discharge circuit configured to apply a machining voltage to the inter-electrode gap and allow a machining current to flow therein,

wherein the wire electrical discharge machining device is configured to process the work by repeating a series of cycle including an operation and a pause of the discharge induction circuit and the main discharge circuit,

the cycle comprising an operation of the discharge induction circuit, a subsequent operation of the main discharge circuit, and a next subsequent pause time during which the discharge induction circuit and the main discharge circuit are not operated;

a first processor configured to measure a discharge delay time from application of the induction voltage to the inter-electrode gap by the discharge induction circuit until occurrence of the electrical discharge; and

a second processor configured to change at least one of the pause time and an operation time of the main discharge circuit according to the discharge delay time,

wherein, in response to the discharge delay time being less than a predetermined value, the second processor is configured to decrease the pause time compared to a case where the discharge delay time is the predetermined value or more.

5. The wire electrical discharge machining device according to claim 4, wherein, in response to the discharge delay time being less than the predetermined value, the second processor is configured to increase the operation time of the main discharge circuit compared to a case where the discharge delay time is the predetermined value or more.

6. The wire electrical discharge machining device according to claim 4, wherein the second processor is configured to make the operation time of the main discharge circuit longer as the discharge delay time becomes shorter.

7. The wire electrical discharge machining device according to claim 4, wherein the second processor is configured to change at least one of the pause time and the operation time of the main discharge circuit when finishing is performed.

8. A wire electrical discharge machining device, comprising:

a discharge induction circuit configured to apply an induction voltage to an inter-electrode gap between an electrode and a work and configured to induce electrical discharge;

a main discharge circuit configured to apply a machining voltage to the inter-electrode gap and allow a machining current to flow therein,

wherein the wire electrical discharge machining device is configured to process the work by repeating a series of cycle including an operation and a pause of the discharge induction circuit and the main discharge circuit,

the cycle comprising an operation of the discharge induction circuit, a subsequent operation of the main discharge circuit, and a next subsequent pause time during which the discharge induction circuit and the main discharge circuit are not operated;

a first processor configured to measure a discharge delay time from application of the induction voltage to the inter-electrode gap by the discharge induction circuit until occurrence of the electrical discharge; and

a second processor configured to change at least one of the pause time and an operation time of the main discharge circuit according to the discharge delay time,

wherein the second processor is configured to make the pause time shorter as the discharge delay time becomes shorter.

9. The wire electrical discharge machining device according to claim 8, wherein, in response to the discharge delay time being less than a predetermined value, the second processor is configured to increase the operation time of the main discharge circuit compared to a case where the discharge delay time is the predetermined value or more.

10. The wire electrical discharge machining device according to claim 8, wherein the second processor is configured to make the operation time of the main discharge circuit longer as the discharge delay time becomes shorter.

11. The wire electrical discharge machining device according to claim 8, wherein the second processor is configured to change at least one of the pause time and the operation time of the main discharge circuit when finishing is performed.