JPH0478410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for restarting electrical discharge machining when a wire breakage or wire short circuit occurs in a wire-cut electrical discharge machine.

[Technical background of the invention and its problems] In a wire-cut electrical discharge machine that performs automatic electrical discharge machining, if a wire breakage or wire short circuit occurs during processing, it becomes difficult to continue processing, causing a major hindrance to the processing schedule. . Therefore, if the processing machine cannot be constantly monitored due to late-night work, etc.,
The machining conditions and machining speed were lowered, and the machining was performed under extremely safe conditions that would prevent wire breakage or wire short circuits. However, in recent years, even if such a wire breakage or wire short circuit occurs, the wire electrode is automatically processed at the break or short circuit point on the processing path, then the process returns to the processing start point, automatic wire connection processing is performed at the start point, and then the processing continues An automatic wire connection rework processing system has been developed that returns the wire along the path to the point of breakage or short circuit and restarts the process, making it difficult for problems to occur even when unmanned machining is performed under efficient machining conditions and speed.

However, when using such a conventional automatic wire connection processing restart method, even after returning to the wire breakage or short circuit point and restarting processing, the processing waste that caused the wire breakage may remain, or the short circuit may not be dealt with. Because this was not done, wire breakage and wire short circuits occurred again.

This is caused by a wire electrode breakage problem that occurs when the removal of machining debris during machining is not carried out smoothly, and concentrated electrical discharge occurs through the machining debris, causing local wear of the wire electrode. This is because when processing is restarted at the point of wire breakage, the situation at the time of wire breakage is reproduced as it is, and wire breakage is likely to occur again. Wire short circuit accidents also occur when machining waste is not removed, machining defects occur, and the machining speed is not set according to the machining conditions.If machining is restarted without removing the cause of the short circuit, a short circuit will occur. This is because it is likely to recur.

[Purpose of the Invention] The present invention was made in view of the above-mentioned conventional problems, and it restarts the machining at a point where the machining path has gone backwards by a set distance, and returns to the point where the disconnection or short circuit trouble has occurred. It is an object of the present invention to provide a method for restarting machining in a wire cut electrical discharge machine that effectively eliminates certain machining waste and reduces the possibility of recurrence of an accident.

[Structure of the Invention] When a wire breakage or a wire short circuit occurs, the present invention moves backward on the processing path by a set distance, and at the point where the back movement is completed, removes the broken wire or removes the wire for the next wire supply. A wire cutting electric discharge characterized in that the short-circuited portion is cut, the wire is then returned to the starting point, the wire is reconnected, the machining path is proceeded again to the point where the reverse movement is completed, and the electric discharge machining is restarted at the point where the reverse movement is completed. This is a method for restarting processing on a processing machine.

[Embodiments of the Invention] FIG. 1 shows the entire wire-cut electric discharge machine, in which a wire electrode 3 wound around a feed-out reel 1 is fed out by the drive of a feed-out motor 5, and tension rollers 7, It is communicated with the pinch roller 11 via the lift roller 9. This pinch roller 11 is for feeding the wire electrode 3 toward the workpiece W at a constant speed.

The wire electrode 3 let out from the pinch roller 11 is then wound up by a winding roller 13 and taken out by a take-out roller 15.

A high voltage is applied between the wire electrode 3 and the workpiece W, and the workpiece W is cut by electrical discharge.

The wire electrode 3 is automatically inserted into a start hole of the workpiece W at the start point of processing the workpiece W, and connected so as to be automatically wound up by the winding roller 13. In order to cut the wire electrode 3, the lift roller 9 is raised by the lift motor 17 to apply tension to the wire electrode 3.
In this state, a current is passed through the wire electrode 3 by a wire cutting machine (not shown) to fuse and cut it.

Regarding the method for restarting machining after wire breakage or wire short circuit in the above wire cut electric discharge machine,
Next, a description will be given based on FIGS. 2 and 3.

The wire electrode 3 is positioned at the position of a hole drilled at the processing start point ST of the workpiece W, and the wire electrode 3 is inserted through the hole to perform automatic wire connection.
(Step 21) Electric discharge machining of the workpiece W is started by applying a voltage between the wire electrode 3 and the workpiece W to generate electric discharge. (Step 23) This electrical discharge machining is
The workpiece W is cut into a desired shape by the relative two-dimensional movement between the workpiece W and the electrode 3.

If a wire breakage or wire short circuit accident occurs during electrical discharge machining, the wire cut electrical discharge machine detects the wire breakage or short circuit and immediately stops electrical discharge machining. (Steps 25 and 27) Immediately, interpolation calculations are performed to carry out the set distance in the direction of the machining path where machining has already been completed, and based on the interpolation calculations, the machining path is moved backwards by a predetermined distance away from the accident point BP. Go backwards to the point RP, and the backward movement completion point RP
Remember. (Steps 29, 33) At this retrograde completion point RP, in the event of a wire short-circuit accident, the wire electrode 3 is automatically cut by the method described above in order to automatically supply the next wire. Further, in the case of a wire breakage accident, the broken wire is rolled up and removed from the workpiece W by driving the winding roller 13. (Step 35) Thereafter, the process returns to the processing start point ST, the processing program on the processing machine side is also reset to the program from the start point ST, and the wire electrode 3 is automatically connected. (Steps 37, 39) Move to the reverse completion point RP at the rapid feed speed while tracing the actual machining path. (Steps 41, 43) When this reverse completion point RP is reached, electrical discharge machining is restarted. If necessary, the machining conditions and machining speed at this time are automatically set lower than the machining conditions and machining speed before the accident until the accident point BP.
Once the accident point BP is reached, the machining conditions and machining speed may be set to the original values. After this, electrical discharge machining is continued until machining is completed. (Step 47) If a wire breakage or wire short circuit occurs during electrical discharge machining, the machining path is reversed by a set distance, and preparations for the next wire supply are made at the point RP where the reversal is completed. After completing the preparation, return to the starting point ST, perform automatic wire connection, proceed along the machining path again, and when you reach the point where wire supply preparations were made, resume electrical discharge machining to prevent wire breakage or short circuits. This effectively eliminates machining debris and broken wires at the point BP where the accident occurred, and enables smooth automatic resumption of machining.

[Effects of the Invention] When a wire breakage or short circuit occurs, this invention removes the broken wire and machining waste at a point that is reversed by a predetermined distance, and also cuts the short-circuited part of the wire electrode, and discharges the wire before the accident point. Processing is automatically restarted. Therefore, even if machining debris remains at the accident point, it is possible to start electric discharge, and the situation before the accident can be reproduced as in the conventional case where the electric discharge machining is restarted when the accident point is reached. Processing can be restarted smoothly without having to do anything.

[Brief explanation of the drawing]

FIG. 1 is an overall view of a wire-cut electrical discharge machine using an embodiment of the present invention, FIG. 2 is a plan view showing the electrical discharge machining path of a workpiece according to an embodiment of the present invention, and FIG. This is a flowchart of the program to be executed. 1... Delivery reel, 3... Wire electrode, 9... Lift roller, 11... Pinch roller, W... Workpiece,
13... Winding roller, BP... Accident point, RP... Reverse completion point, ST... Start point.

Claims (1)

[Claims] 1. When a wire breakage or wire short circuit occurs,
It moves backward on the processing path by a set distance, and at the point where the backward movement is completed, it removes the broken wire or cuts the short-circuited part of the wire in order to supply the next wire.
Next, return to the starting point and reconnect the wires.
A machining restart method for a wire-cut electric discharge machine, characterized in that the machining path is moved again to the point where the reverse movement is completed, and the electric discharge machining is restarted at this point where the reverse movement is completed.