JPH0732968B2 - Wire cut electric discharge machine - Google Patents

Description

Description: [Industrial field of use] The present invention relates to high accuracy of a wire cut electric discharge machine.

[Prior Art] FIG. 4 is a schematic view showing a configuration of a conventional wire-cut electric discharge machine.

In the figure, (1) is a wire electrode, (2) is a work piece, (3) is an X slider for moving the work piece (2) in the horizontal direction in the figure, and (4) is a work piece (2). Is moved in the front-back direction in the figure, (5) is a servo motor that drives the X slider (3), (6) is a servo motor that drives the Y slider (4), and (7) is a servo motor (5) Servo amplifier for supplying current to the motor, (8) servo amplifier for supplying current to the servomotor (6), and (9) supplying pulsed voltage between the wire electrode (1) and the workpiece (2). A machining power source, (10) a detector for detecting the average machining voltage between the wire electrode (1) and the workpiece (2),
Reference numeral (11) is a control device for controlling the servo amplifiers (7), (8) based on the signal from the detector (10) and a predetermined machining program.

Next, the operation will be described. The wire-shaped electrode (1) is run at a predetermined speed, and a pulsed voltage is applied between the wire-shaped electrode (1) and the workpiece (2) from the processing power source (9), so that the wire-shaped electrode (1) ) And the workpiece (2) are caused to generate electric discharge. that time,
A movement command signal is transmitted to the servo amplifiers (7), (8) based on the program locus given to the control device (11) in advance, and the servo motor (5),
(6) is an X slider (3) and a Y slider (4)
It is possible to process a desired shape by driving.
Generally, the processing condition changes from time to time, so the control device (11)
Is an X-slider (3) and a Y-slider at an optimum feed rate so that the machining gap between the wire-shaped electrode (1) and the workpiece (2) becomes constant by the average voltage between the poles detected by the detector (10). (4) is driven. Normally, it is possible to obtain good shape accuracy and surface roughness by carrying out end face finishing several times after roughing. By the way, the shape accuracy after finishing is determined by the electrode side surface gap, and it is necessary to make this electrode side surface gap constant in order to perform highly accurate shape processing. Fifth
The figure is an enlarged view of the wire-shaped electrode (1) and the workpiece (2) during the finishing process. However, in the conventional general average voltage constant control, the machining speed is increased when the removal amount L is increased. Is reduced, and as a result, the side surface of the wire (A in the figure
Part), the machining integration effect is increased and the electrode side surface gap Gs is increased. That is, even if the machining electrical condition and the average servo voltage are the same, the electrode side surface gap Gs is not constant when the removal amount L changes, and the post-machining shape accuracy deteriorates. Sixth
The figure shows the relationship between the removal amount L and the electrode side surface gap Gs under the same machining electrical condition and average servo voltage.
It can be seen that is greatly changed. In the actual shape processing, the change in the removal amount L becomes the maximum at the corner portion, and Fig. 7 shows the wire electrode (1) and the workpiece (2) at the time of the sharp edge / out-corner finish processing enlarged. It is a figure. From the figure, it can be seen that the machining amount (L2-L5) at the corner changes to a much smaller value (zero at the edge) than the machining amount (L0, L6) during straight line machining.
Fig. 8 is a diagram that tightens the change in the amount L taken at the sharp edge / out-corner part, and the amount taken L is constant until it decreases from a certain distance (H1 in the figure) close to the edge part in the figure and in front of it. Becomes zero (0), and the take-up amount L begins to increase from a certain distance (H3 in the figure) after the direction change at the edge portion, and the take-up amount again becomes at the straight line processed portion.

Therefore, as described above, the electrode side surface gap Gs also changes with the change in the removal amount L, especially in the sharp edge / out-corner portion, so that the post-processing molding deteriorates. Furthermore, because the processing speed becomes extremely high at the edge,
Machining progresses (overshoot) in a state where the machining speed does not decrease in the straight machining immediately after the direction change,
Undercut (protruding shape) occurs as shown in the figure. For this reason, in the sharp edge / out-corner portion, the processing accuracy is extremely deteriorated by a normal servo.

[Problems to be Solved by the Invention] Since the conventional wire-cut electric discharge machine is configured as described above, a change in the take-up amount L and an overshoot that occur particularly in the sharp edge / out-corner portion are accompanied. There has been a problem that the wire electrode side surface gap Gs changes, and as a result, the accuracy of the shape after processing is significantly deteriorated.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a wire cut electric discharge machine that significantly improves the machining accuracy at the out-corner portion.

[Means for Solving Problems] A wire-cut electric discharge machine according to the present invention generates an electric discharge by applying a voltage between a wire-shaped electrode and a workpiece which face each other, and at the same time, a machining average between electrodes. The outer circumference of the workpiece having the out-corner portion is detected by detecting the voltage and moving the slider by a servomotor to control the relative transfer speed between the wire electrode and the workpiece so as to keep the average voltage between the electrodes constant. In a wire-cut electric discharge machine that performs machining, the first discriminating means that outputs a signal when the machining speed reaches a predetermined speed that is higher than the machining speed during normal machining of a portion other than the out-corner, and machining average voltage And a first discriminator that outputs a signal when a predetermined voltage higher than the machining average voltage during normal machining of parts other than the out corner is reached. And a controller for maintaining the machining speed at the predetermined speed when both the signals are output from the step and the second discriminating means.

Further, it is provided with setting means for automatically setting the predetermined speed of the first judging means and the predetermined voltage of the second judging means in accordance with processing conditions.

[Operation] In the wire-cut electric discharge machine according to the present invention, when the machining speed at the out-corner portion reaches a predetermined speed that is higher than the machining speed during normal machining of the portion other than the out-corner, the machining speed is set to Maintained at the specified speed.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, (1) is a wire electrode, (2) is a work piece, (3) is an X slider for moving the work piece (2) in the horizontal direction in the figure, and (4) is a work piece ( Y slider for moving 2) in the front-back direction in the figure, (5) a servomotor for driving the X slider (3), (6) for a servomotor for driving the Y slider (4), and (7) for a servomotor ( 5) a servo amplifier for supplying a current, (8) a servo amplifier for supplying a current to the servo motor (6), (9) a pulse voltage between the wire electrode (1) and the workpiece (2) , A detector for detecting the average machining voltage between the wire electrode (1) and the workpiece (2),
(11) is a control device for controlling the servo amplifiers (7), (8) based on the signal of the detector (10) and a predetermined machining program, and (12) is a normal machining of the portion other than the out-corner at the machining speed. The first discriminator that determines whether or not the machining speed has reached a predetermined speed that is higher than the machining speed when (14) reaches a predetermined voltage that is higher than the machining average voltage during normal machining of parts other than the out corners. A second discriminator for discriminating whether or not the machining is performed, (17) is a setter for automatically setting predetermined values of the machining speed and the machining average voltage in accordance with the machining conditions, and (13) is a discrimination for each. This is a control device that maintains the processing speed at a predetermined speed by the signals of the devices (12) and (14).

Next, the operation of the embodiment of the present invention will be described.

The wire-shaped electrode (1) travels at a predetermined speed as in the conventional case, and a pulse voltage is applied between the wire-shaped electrode (1) and the workpiece (2) from the machining power supply (9) to The machining is performed by generating an electric discharge between the electrode (1) and the workpiece (2).
A movement command signal is transmitted to the servo amplifiers (7) and (8) based on the program locus given to (1), and the servo motors (5) and (6) receive the X-slider (3) and Y-slider ( 4) is driven to process a desired shape. The control device (11) uses the wire-shaped electrode (1) according to the average voltage between the poles detected by the detector (10).
Drive the X slider (3) and Y slider (4) at the optimum feed rate so that the machining gap between the workpiece and the workpiece (2) will be constant, and carry out end face finishing several times after rough machining. To obtain good shape accuracy and surface roughness. As described above, the shape accuracy after finishing is determined by the electrode side surface gap, and it is important to keep this electrode side surface gap constant in order to perform highly accurate shape processing.

In the finishing process, the first discriminator (12) generates a signal when the removal amount is reduced and the processing speed reaches the above-mentioned predetermined speed. The discriminator (14) shown in FIG. 2 emits a signal when the machining gap voltage reaches the above-mentioned predetermined voltage because the gap between the electrodes becomes open at the out-corner portion. Here, the setting device (17) automatically determines and sets a predetermined value (predetermined speed, predetermined voltage) of the machining speed and the machining average voltage from the information on the machining electrical condition from the control device (11). That is, the predetermined values of the machining speed and the machining average voltage are automatically set to optimum values every time the machining conditions such as 2nd cut, 3rd cut and 4th cut are switched. Further, during the finishing process, the control device (13) controls the signals of the first and second discriminators (12) and (14) to prevent the machining speed from further increasing when the machining speed reaches a predetermined speed. Lock the processing speed. At the end of the out corner, the removal amount starts to increase again, and at the same time as the machining speed starts to drop below a predetermined value, the lock is released and the servo between poles normally returns. In addition, when the machining amount reaches a predetermined speed due to a decrease in the amount of machining in the area other than the out corner, the second discriminator (14) does not generate a signal because the machining average voltage does not rise to the predetermined voltage. Therefore, the control device (13) does not lock the processing speed. That is, the two discriminators (12) and (14) ensure that the machining speed is locked only at the out-corner,
Even if the processing speed is increased in other parts, the processing speed is not locked. FIG. 2 shows how the machining speed changes during machining of the sharp edge-out corner portion in this embodiment. Since the machining speed is locked at an appropriate value at the edge part, the machining speed immediately decreases even in the straight-line machining immediately after the direction change, overshoot does not occur, and as shown in Fig. 9 generated by the conventional servo. Undercut (protruding shape) does not occur. Also, as mentioned above, as the 2nd cut, 3rd cut, and 4th cut progress, the undercut (protruded shape) is always locked at the optimal processing speed in each case. It is the smallest. FIG. 3 shows an example in which the shapes of the sharp edge-out corners processed by the wire-cut electric discharge machine in this example and the conventional example are compared. It should be noted that these series of operations are automatically performed for all the corners being machined without the operator having to switch or operate them.

In the above embodiment, the limiting device (11), the first discriminator (12), the second discriminator (14), the setting device (17), and the control device (13) are independently provided. Although shown, these may be performed by one control device if equivalent functions can be performed. Further, in the above embodiment, an example in which control is performed for a sharp edge out corner is shown, but similar effects can be obtained by performing similar control for other out corners.

[Effects of the Invention] As described above, according to the present invention, the out-corner portion is surely discriminated by a plurality of discrimination parameters, and the machining speed at the out-corner portion is maintained at an optimal predetermined speed at each stage during finishing machining. With such a configuration, the effect of preventing the overshoot phenomenon and significantly improving the processing accuracy at the out-corner portion can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a wire-cut electric discharge machine in one embodiment of the present invention, FIG. 2 is a view showing a change in machining speed at a sharp edge-out corner portion in this embodiment, and FIG. The figure which compared the sharp edge shape machined with the wire cut electric discharge machine in an Example and the conventional example, FIG. 4 is a block diagram which shows the conventional wire cut electric discharge machine, and FIG. Fig. 6 is an enlarged view of the work piece, Fig. 6 is a diagram showing the relationship between the amount of removal and the electrode side surface gap, Fig. 7 is an enlarged view of the wire electrode and the work piece during the sharp edge-out corner finishing, and Fig. 8 is a sharp view. Diagram showing the change in removal amount at the edge and out corners,
FIG. 9 is a view showing an undercut (protruding shape) after processing a sharp edge / out corner portion in a conventional example. In the figure, (1) is a wire electrode, (2) is a workpiece, (12) is a first discriminator, (13) is a control device, and (14).
Is a second discriminator, and (17) is a setter. In the drawings, the same reference numerals indicate the same parts.

Claims (2)

[Claims] 1. A discharge is generated by applying a voltage between opposing wire-shaped electrodes and a workpiece, and a machining average voltage between the electrodes is detected to keep the average voltage between the electrodes constant. In a wire-cut electric discharge machine that processes the outer circumference of a work piece that has an out-corner part by moving the slider with a servo motor to control the relative movement speed of the wire electrode and the work piece, the machining speed is out-corner. The first determining means for outputting a signal when it reaches a predetermined speed that is higher than the normal processing speed of the portion other than the above, and the processing average voltage is higher than the processing average voltage of the portion other than the out corner during the normal processing. Second discriminating means for outputting a signal when a high predetermined voltage is reached; and the first discriminating means.
A wire-cut electric discharge machine comprising: a controller for maintaining the machining speed at the predetermined speed when both the above-mentioned signals are output from the above-mentioned discrimination means and the above-mentioned discrimination means. 2. A discharge is generated by applying a voltage between opposing wire-shaped electrodes and a workpiece, and a machining average voltage between the electrodes is detected to keep the average voltage between the electrodes constant. In a wire-cut electric discharge machine that processes the outer circumference of a work piece that has an out-corner part by moving the slider with a servo motor to control the relative movement speed of the wire electrode and the work piece, the machining speed is out-corner. The first determining means for outputting a signal when it reaches a predetermined speed that is higher than the normal processing speed of the portion other than the above, and the processing average voltage is higher than the processing average voltage of the portion other than the out corner during the normal processing. A second discriminating means for outputting a signal when a high predetermined voltage is reached, and the predetermined speed and the second discriminating means for the first discriminating means according to processing conditions.
When the setting means for automatically setting the predetermined voltage of the discriminating means and the respective signals from the first discriminating means and the second discriminating means are both output, the machining speed is maintained at the predetermined speed. A wire-cut electric discharge machine equipped with a control device.