JPH04289026A - Short circuit releasing method for wire cut electric discharge machine - Google Patents

Abstract

PURPOSE:To surely release short circuit between a wire and a work and quickly start machining again. CONSTITUTION:Electric discharge machining is started from a starting point A of machining, and the machining is put forward along a prescribed machining route 23. When short circuit is generated at B point on the way of the machining route 23, a short circuit detected signal is sent to a numerical control device 2, and a wire is moved with the numerical control device 2 according to the short circuit detected signal. Namely, the wire is moved in the direction at prescribed angle alpha against the machining route 23 up to the point, and when release of short circuit is detected at C point on the way of movement in the direction of angle alpha, the wire is turned back to the short circuit generated point B along the moved route. When the wire is returned at the short circuit generated point B, the machining is continued along the machining route 23.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short-circuit release method for a wire-cut electrical discharge machine used to release a short-circuit between a wire and a workpiece during electrical discharge machining, and more particularly to a short-circuit release method that can reliably release a short-circuit.

0002

[Prior Art] A wire-cut electric discharge machine generates a pulse electric discharge between a wire and a workpiece, melts a part of the workpiece, and blows off the melted part with a nozzle or the like.
This is operated continuously to finish the work into the desired shape. By the way, during this wire cut electrical discharge machining,
If a short circuit occurs between the wire and the workpiece, machining cannot be continued because electrical discharge is no longer possible. FIG. 4 is a diagram showing a wire and a workpiece during electrical discharge machining, in which (A) shows a case where electrical discharge machining is performed normally, and (B) shows a case where a short circuit occurs. As shown in (A), the wire 20 and the workpiece 6
Normal electrical discharge machining is performed when the wires 20 and workpiece 6 are kept at a small distance due to electrical discharge, but as shown in (B), if the wire 20 and workpiece 6 come into contact and short-circuit, machining cannot continue. . So, when a short circuit is detected,
At that point, the wire is temporarily retreated along the machining path that has already been machined, and if a short-circuit release is detected during the retreat, it is returned along the retreated path to the short-circuit point and machining is continued from the short-circuit point. ing.

0003

However, even if the wire is moved back along the machining path, the short circuit may not be released. For example, in electrical discharge machining, machining conditions are usually changed little by little and machining is performed several times before finishing. However, during the second or third cut, if the machining conditions are not set properly, the wire and workpiece may short at the corner. In such a case, the short circuit may not be removed even if the wire is retracted. This is because the contact between the wire and the workpiece cannot be removed even if the wire is moved along the machining path that has already been machined. Therefore, it is necessary to temporarily stop the machining and manually release the short circuit, which poses a problem in that it takes time to release the short circuit and restart the machining. The present invention has been made in view of these points, and it is an object of the present invention to provide a short-circuit release method for a wire-cut electric discharge machine that can reliably release a short-circuit and promptly restart machining.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a short-circuit release method for a wire-cut electrical discharge machine that releases a short circuit that occurs between a wire and a workpiece during electrical discharge machining. A short circuit between a wire and a workpiece is detected, and when the short circuit is detected, the wire is moved from the short circuit point along a preset moving direction of the wire, and when the wire moves from the short circuit point, the wire is moved from the short circuit point. There is provided a short-circuit release method for a wire-cut electric discharge machine, characterized in that when the short-circuit release is detected, the short-circuit is returned to the short-circuit point and the electric discharge machining is continued from the short-circuit point.

[0005]

[Operation] Detects short circuit between wire and workpiece during electrical discharge machining. When a short circuit is detected, the wire is moved from the short circuit point along a preset wire movement direction. When the short-circuit release is detected when the wire moves from the short-circuit point,
Return to the short circuit point again and continue electrical discharge machining from that short circuit point. Therefore, the short circuit is reliably released, and after the short circuit occurs,
Processing can be resumed promptly.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a schematic configuration of a wire-cut electric discharge machine according to the present invention. In the figure, the wire-cut electrical discharge machine is comprised of a numerical control device 2 and an electrical discharge machine main body 30. The processing instruction tape 1 is a tape on which a processing program is punched. The numerical control device 2 reads the machining program from the machining command tape 1, decodes the machining program, drives the servo motors 3 and 4, and controls the XY table 5.
The entire processing machine 30 is controlled, such as movement of the machine. XY table 5
is movable in two orthogonal axes directions by servo motors 3 and 4. A workpiece 6 made of a conductive material is placed on the XY table 5. An upper wire guide 7 and a lower wire guide 10 for holding a wire 20 are provided above and below the XY table 5 and the workpiece 6. These upper and lower wire guides 7 and 10 are for accurately positioning the wire 20 with respect to the workpiece 6. The wire 20 is continuously fed out from the feeding reel 9 and reaches the workpiece 6 via the brake 8 and the upper wire guide 7. The wire 20 that has passed through the workpiece 6 passes through the XY table 5 and is then stored in a wire take-up reel (wire collection box) 12 via a lower wire guide 10 and a wire feeding roller 11.

The electric discharge machining voltage is supplied from the machining power source 14 to the wire 20 by a feeder 13 provided between the upper wire guide 7 and the brake 8. On the other hand, the other end of the machining power source 14 is electrically connected to the workpiece 6 via a switch 16 that is opened and closed by a discharge control means 15. The discharge control means 15 changes the machining characteristics by controlling the on/off time width of the discharge current. The discharge control means 15 is provided with a short circuit detection means 21 which electrically detects a short circuit between the wire 20 and the workpiece 6 and sends the detection signal to the numerical control device 2. In response to the signal, the numerical control device 2 issues a command to release the short circuit to the processing machine main body 30.
to control the operation of the wire 20. The details will be described later. The machining liquid treatment tank 17 is composed of a tank, a filter device, an ion exchanger, etc., and injects machining liquid from an injection nozzle 18 into the machining portion of the workpiece. As described above, based on the control signal of the numerical control device 2, the XY table 5 is moved by the servo motors 3 and 4, the wire is fed while water is injected from the injection nozzle 18, and between the wire and the workpiece 6,
Machining the workpiece by performing intermittent discharge. When the intermittent discharge is performed, the surface of the workpiece 6 is vaporized and melted, and the workpiece 6 is processed into a desired shape.

FIG. 1 is a diagram for explaining a method for releasing a short circuit in a wire-cut electrical discharge machine according to the present invention. The first cut of the workpiece 6 has been completed, and a rectangular hole 22 has been formed in the center. Here, the second cut starts from the machining start point A, and the machining progresses along the preset machining path 23. At point B in the middle of the processing path 23,
When a short circuit occurs, the short circuit detection signal is sent to the numerical control device 2 as described above, and the numerical control device 2 moves the wire 20 as follows in response to the short circuit detection signal. That is, the wire 20 is moved in the direction of a preset angle α with respect to the machining path 23 up to that point. The setting of this angle α is performed, for example, by an operator inputting it into the numerical control device 2 using a keyboard. The angle α can be set to any value by the operator. When the release of the short circuit is detected at the point C while moving in the direction of the angle α, the wire 20 is returned along the movement path to the point B where the short circuit occurs. Once the wire 20 has returned to its short circuit point B, machining continues along the machining path 23.

FIG. 3 is a flowchart for carrying out the present invention. In the figure, the number following S indicates the step number. [S1] Direction of movement of wire 20 during short circuit (angle α)
Set. [S2] Start processing. [S3] Determine whether a short circuit has occurred. If a short circuit has occurred, the process proceeds to step 4, and if no short circuit has occurred, the process proceeds to step 7. [S4] The wire 20 is moved along the set movement direction. [S5] Determine whether the short circuit has been released. When the short circuit is removed, the process proceeds to step 6, and when the short circuit is not removed, the process returns to step 4. [S6] Return the wire to the point B where the short circuit occurred. [S7] Processing continues from short circuit occurrence point B. In this way, when a short circuit occurs during electrical discharge machining, the wire 20 is moved along the preset moving direction of the wire 20.
It was configured to move. Therefore, compared to the conventional method of retracting the wire 20 along the machining path 23 that has already been machined, the contact state between the wire 20 and the workpiece 6 is
removed more reliably. Therefore, the short circuit is reliably released, and machining can be promptly restarted after the short circuit occurs.

0010

As described above, the present invention is configured so that when a short circuit occurs during electrical discharge machining, the wire is moved along a preset movement direction. Therefore, the contact state between the wire and the workpiece can be removed more reliably than in the conventional method of retracting the wire along a machining path that has already been machined. Therefore, the short circuit can be reliably released, and processing can be promptly restarted after the short circuit occurs.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a short-circuit release method for a wire-cut electrical discharge machine according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of a wire-cut electrical discharge machine of the present invention.

FIG. 3 shows a flowchart for carrying out the invention.

FIG. 4 is a diagram showing a wire and a workpiece during electrical discharge machining,
(A) shows the case when electrical discharge machining is performed normally, (B)
indicates the case of short circuit.

[Explanation of symbols]

2 Numerical control device 6 Work 15 Discharge control means 20 Wire 21 Short circuit detection means 23 Processing path α Setting angle

Claims (3)

[Claims] 1. A short-circuit release method for a wire-cut electrical discharge machine that releases a short-circuit between a wire and a workpiece during electrical discharge machining, wherein a short-circuit between the wire and the workpiece during electrical discharge machining is detected, and the short-circuit is removed. At the time of detection, the wire is moved from the short-circuit point along a preset wire movement direction, and when the short-circuit release of the wire is detected when the wire is moved from the short-circuit point, the wire is returned to the short-circuit point again. ,
A method for releasing a short circuit in a wire-cut electric discharge machine, characterized in that the electric discharge machining is continued from the short circuit point. 2. The short-circuit release method for a wire-cut electric discharge machine according to claim 1, wherein the moving direction of the wire at the time of the short-circuit is set to an arbitrary direction. 3. The short-circuit release method for a wire-cut electric discharge machine according to claim 1, wherein the moving direction of the wire at the time of the short-circuit is set by an angle of the wire with respect to a machining path.