JPH079261A - Method and device for wire electric discharge machining - Google Patents

Abstract

PURPOSE:To make processing of an in-corner shape having a small min. corner radius and enhance the accuracy in finish processing of the in-corner part. CONSTITUTION:A method and device for wire electric discharge machining comprises a computing device 20, which calculates the locus of movement such that the circular arc loci in the corner part processing in different machining processes get the same diameter, and a control device 11 which performs the locus movement such that the corner part radii in different machining processes become the same on the basis of the result from computing made by the computing device 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire electric discharge machining method and apparatus for machining by relatively moving a wire electrode and a workpiece while applying a voltage between the opposing wire electrode and the workpiece. In particular, the present invention relates to improvement of machining accuracy of an in-corner portion in wire electric discharge machining.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional electric discharge machine. In the figure, 1 is a wire electrode, 2 is a workpiece, 3 is a power source for machining, 4 is an X table for moving the workpiece 2 in the X direction, 5 is a Y table for moving the workpiece 2 in the Y direction, 6
a and 6b are motors for moving the X table and Y table, 7a and 7b are servo amplifiers for driving the motors 6a and 6b, 8 is an NC program, 9 is a storage device for storing offset data, 10 is an NC program and An arithmetic unit that calculates the machining path based on the offset data,
Reference numeral 11 denotes a control device that controls the actual axis movement from the machining trajectory calculated by the arithmetic device 10.

Next, the operation will be described. In the conventional example, the wire electrode 1 is run by a wire electrode running device (not shown), and working is performed while a pulse current is supplied between the wire electrode 1 and the workpiece 2 by the working power supply 3.
The arithmetic unit 10 calculates the machining locus based on the NC program and offset data given in advance in the memory or the NC tape. The control device 11 determines the servo amplifier 7 for XY movement based on the calculation result of the machining locus.
Machining is performed by outputting a movement command to a and 7b and driving the motors 6a and 6b to relatively move the wire electrode 1 and the workpiece 2 in a two-dimensional manner.

FIG. 7 shows a processing locus for finishing the in-corner portion in the conventional example. When finishing the in-corner part, the final processing pass (4th cu
Processing is performed by changing the corner radius in each processing pass (1st to 4st cuts in the figure) so that the processed shape after t) has a desired radius R. That is, the locus movement is performed so that the corner radius in each machining pass becomes a value obtained by subtracting the offset value in each machining pass from the program radius R (final desired radius) as described below. Rn = R-Hn where Rn: corner radius in the nth machining, R: program radius Hn: offset value in the nth machining

[0005]

Since the conventional electric discharge machining apparatus is constructed as described above, it is necessary to gradually increase the corner radius in the process from rough machining to final finishing in finishing machining. There was a problem that the corner radius finally obtained would be large. Therefore, for example, the minimum radius of the in-corner that can be finished with a wire electrode having a diameter of 0.2 mm is limited to about 0.2 mm.

The present invention has been made in order to solve the problems of the conventional ones described above, and it is possible to greatly reduce the machinable in-corner radius and improve the machining accuracy in the in-corner finishing. An object of the present invention is to provide a wire electric discharge machining method and an apparatus thereof.

[0007]

According to the wire electric discharge machining method of the present invention, machining is performed while moving the machining locus of the in-corner portion in each machining step along a locus having the same radius.

Further, the wire electric discharge machining apparatus according to the present invention calculates the movement locus of the in-corner portion in each machining step so that the arc loci in the machining of the in-corner portion of the machining steps having different offset values have the same radius. And a control device for moving the locus such that the in-corner radii of the respective machining steps are the same based on the calculation result of the calculation means.

In the wire electric discharge machining method according to the present invention, the machining locus of the in-corner portion in each machining step is
While moving along a locus of the same radius, machining is performed while changing machining conditions such as machining electrical conditions and feed rates according to changes in the removal amount at the in-corner portion.

Furthermore, the wire electric discharge machining apparatus according to the present invention calculates the movement locus of the in-corner portion in each machining step so that the arc loci in the machining of the in-corner portions of the machining steps having different offset values have the same radius. First
Of the calculation means, the first control means for moving the locus so that the in-corner radius of each machining process becomes the same based on the calculation result of the calculation means, and the change of the removal amount at the in-corner part of each machining process. And second control means for changing and controlling machining electric conditions, feed rate, etc. at the in-corner portion based on the result of the second calculation means.

[0011]

The wire electric discharge machining method and apparatus according to the present invention perform machining while moving the machining locus of the in-corner portion in each machining step along a locus of the same radius.

Further, the wire electric discharge machining method and the apparatus therefor according to the present invention move the machining locus of the in-corner portion in each machining step along a locus having the same radius and respond to the change of the removal amount at the in-corner portion. Machining is performed while changing machining conditions such as electrical conditions and feed rate.

[0013]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to FIGS. 1 and 2. 1 is a configuration diagram showing a first embodiment of the present invention, in which 1 is a wire electrode, 2 is a workpiece, 3 is a power source for machining,
4 is an X table for moving the workpiece 2 in the X direction, 5 is a Y table for moving the workpiece 2 in the Y direction, 6a and 6b are X tables, motors for moving the Y table, 7a, 7
b is a servo amplifier that drives the motors 6a and 6b, 8 is an NC program, 9 is a storage device that stores offset data, 21 is a setting switch that selects whether the machining at the in-corner portion is standard machining or the same R machining, When the setting switch 21 designates the same R, the reference numeral 20 indicates the in-corner portion of each process such that the arc loci in the machining of the in-corner portion of each machining process having different offset values have the same radius based on the NC program and the offset data. An arithmetic unit which is a first arithmetic unit for calculating a movement trajectory, 11
Is a control device, which is a first control means, that controls the locus movement such that the in-corner radius of each machining process becomes the same from the machining locus calculated by the arithmetic unit 20.

Next, the operation will be described. In FIG. 1, similarly to the conventional example, a wire electrode traveling device (not shown) travels the wire electrode 1, and a machining power source 3 performs machining while supplying a pulse current between the wire electrode 1 and the workpiece 2. The arithmetic unit 20 has a memory or NC in advance.
The machining path is calculated based on the NC program and offset data given on the tape.
When the setting of 1 is the same R designation, the movement locus of the in-corner portion in each process is calculated such that the arc loci in the machining of the in-corner portion of the machining processes having different offset values have the same radius. The controller 11 outputs a movement command to the X / Y movement servo amplifiers 7a and 7b based on the calculation result of the machining locus, and drives the motors 6a and 6b to two-dimensionally move the wire electrode 1 and the workpiece 2. It is moved relative to and processing is performed.

FIG. 2 shows a processing locus for finishing the in-corner portion in this embodiment. When finishing the in-corner part, each machining pass (1st to 4st cu in the diagram) from roughing to the final machining pass (4st cut in the diagram)
Processing is performed so that the corner radius in t) becomes constant. Further, when the setting of the setting switch 21 is the standard designation, the arithmetic unit 20 calculates the machining locus for changing the corner radius in each machining path (1st to 4st cuts in the figure) as shown in FIG. 2 as in the conventional example. Then, standard in-corner processing is performed based on this result.

According to the above method, φ can be obtained by the usual processing method.
0.2m as the minimum corner radius of 0.2 wire
By performing the corner processing with the same radius of about m, it is possible to process the minimum corner radius of about 0.15 mm with the φ0.2 wire.

Example 2. The second embodiment of the present invention will be described below with reference to FIGS. 3, 4 and 5. 3 is a block diagram showing a second embodiment of the present invention, in which 1 is a wire electrode, 2 is a workpiece, 3 is a power source for machining, 4 is an X table for moving the workpiece 2 in the X direction, and 5 is a workpiece. Y table for moving the object 2 in the Y direction, 6a, 6b for X table, motor for moving Y table, 7a, 7b for servo amplifier for driving the motors 6a, 6b, 8 for NC program, 9 for offset A storage device for storing data, 21 is a setting switch for selecting whether the machining at the in-corner portion is standard machining or the same R machining, 20 is based on the NC program and the offset data when the setting switch 21 is the same R designation,
An arithmetic unit, which is a first arithmetic means, calculates the movement locus of the in-corner portion in each step such that the arc loci in the machining of the in-corner portions of the machining steps having different offset values have the same radius. The control device, which is the first control means, controls the trajectory movement such that the in-corner radius of each machining step becomes the same from the machining trajectory calculated by An arithmetic unit, which is a second arithmetic unit, for calculating the change in the removal amount at the in-corner portion in the machining pass, 23
Is a control device which is a second control means for changing and controlling the machining electrical condition in the in-corner portion according to the increase / decrease of the removal amount based on the calculation result of the arithmetic device 22.

Next, the operation will be described. In FIG. 3, similarly to the first embodiment, the wire electrode traveling device (not shown) travels the wire electrode 1, and the machining power source 3 performs machining while supplying a pulse current between the wire electrode 1 and the workpiece 2. The arithmetic unit 20 calculates the machining locus based on the NC program and the offset data given in advance in the memory or the NC tape, but when the setting switch 21 is set to the same R designation, the offset value is set as shown in FIG. The movement locus of the in-corner portion in each process is calculated such that the arc loci in the machining of the in-corner portion of each different machining process have the same radius. The control device 11 outputs a movement command to the X / Y movement servo amplifiers 7a and 7b based on the calculation result of the machining locus, and the motors 6a and 6 are driven.
By driving b, the wire electrode 1 and the workpiece 2 are relatively moved in a two-dimensional manner, and machining is performed.

On the other hand, the arithmetic unit 22 calculates the change in the removal amount at the in-corner portion in each machining pass from the machining locus obtained by the arithmetic unit 20. 4 and 5 show changes in the removal amount during in-corner processing. In the figure,
The removal amount is constant at L0 until the electrode center position is O0,
In the linear movement section (section B in FIG. 5) before the circular arc movement where the electrode center position is from O0 to O3, the removal amount sharply increases,
The removal amount becomes maximum at the point of the arc movement start point O3. After that, the removal amount sharply decreases in the arc movement section (section C in FIG. 5) and returns to the straight line removal amount L7 (= L0) at the arc end point O7. The change rate of the removal amount in the same R processing is much higher than the change rate of the removal amount in the conventional standard corner processing as disclosed in JP-A-63-105837. Therefore, the normal average voltage constant feed control cannot respond to such a sudden change in the removal amount,
A short circuit or the like occurs at the in-corner portion, which makes machining extremely difficult and causes a problem that machining accuracy is significantly deteriorated. In this embodiment, the change in the removal amount at the in-corner portion is calculated, and the electromachining condition is changed according to the change in the removal amount to perform the machining.
That is, as shown in FIG.
Since the removal amount sharply increases in the section, the discharge frequency is increased so that the average processing current is increased, and the processing energy is increased. Further, since the removal amount sharply decreases in the arc movement C section, the processing energy also decreases.

According to the above method, φ can be obtained by the usual processing method.
0.2m as the minimum corner radius of 0.2 wire
Although it is about m, by performing corner machining with the same radius and changing and controlling the machining electrical conditions for changes in the removal amount, it is possible to machine with a minimum corner radius of 0.11 mm with φ0.2 wire. It was Further, it has become possible to reduce the shape error in the in-corner portion to 2 μm or less.

Example 3. In the present embodiment, an example in which the processing electrical conditions are changed according to the removal amount at the in-corner portion is shown, but other processing such as the feed speed and the processing locus may be performed to correct the shape after finishing processing. The conditions may be changed. That is, the machining accuracy is improved by performing control so that the feed rate is reduced in the B section before the corner where the removal amount increases and the feed rate is increased in the arc movement C section where the removal amount decreases. Can be planned. Further, in general, when the removal amount increases, there is a tendency for overcut (over-processing) to occur as described in JP-A-63-105837.
By changing the processing locus so as to correct this overcut, it is possible to improve the processing accuracy.

[0022]

As described above, according to the present invention, since the machining locus of the in-corner portion in each machining step is moved while moving along the locus of the same radius, the minimum corner radius that can be machined is set. It can be made extremely small as compared with the conventional one.

Further, according to the present invention, the machining locus of the in-corner portion in each machining step is moved along a locus having the same radius, and the machining electrical condition, the feed rate, etc. are changed according to the change of the removal amount at the in-corner portion. Since the processing is performed while changing the processing conditions, the minimum processable radius of the in-corner can be made extremely small and the processing accuracy of the fine in-corner shape can be significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wire electric discharge machining apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a processing locus for finishing the in-corner portion according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a wire electric discharge machining apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing changes in the removal amount in in-corner processing, for explaining the operation of Example 2 of the present invention.

FIG. 5 is a diagram showing changes in the removal amount in in-corner processing, for explaining the operation of the second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a conventional wire electric discharge machine.

FIG. 7 is a diagram showing a machining locus of finishing machining of an in-corner portion in conventional wire electric discharge machining.

[Explanation of symbols]

 1 Wire Electrode 2 Workpiece 3 Processing Power Supply 4 X Table 5 Y Table 6a, 6b Motor 7a, 7b Servo Amplifier 8 NC Program 9 Offset Storage Device 21 Setting Switch 20 Computing Device 11 Controller 22 Computing Device 23 Controller

Claims (4)

[Claims] 1. A wire electric discharge machining method in which a wire electrode and a workpiece are moved relative to each other while a voltage is applied between the opposing wire electrode and the workpiece, and machining of an in-corner portion in each machining step is performed. A wire electric discharge machining method characterized in that machining is performed while moving a locus along a locus having the same radius. 2. A wire electric discharge machine for performing machining by relatively moving a wire electrode and a workpiece while applying a voltage between the opposing wire electrode and the workpiece. Arithmetic means for calculating the movement locus of the in-corner portion in each machining step so that the circular arc trajectories in the corner portion machining have the same radius, and the in-corner portion radius in each machining step become the same based on the arithmetic result of the arithmetic means. A wire electric discharge machine comprising a control device for performing various trajectory movements. 3. A wire electric discharge machining method in which a wire electrode and a workpiece are moved relative to each other while a voltage is applied between the opposing wire electrode and the workpiece, and machining of an in-corner portion in each machining step is performed. A wire electric discharge machining method characterized in that a locus is moved along a locus having the same radius, and machining is performed while changing machining conditions according to changes in the removal amount at the in-corner portion. 4. A wire electric discharge machine for performing machining by moving a wire electrode and a workpiece relative to each other while applying a voltage between the opposing wire electrode and the workpiece. The first calculation means for calculating the movement locus of the in-corner portion in each machining process so that the circular arc trajectory in the corner machining has the same radius, and the in-corner radius of each machining step is the same based on the calculation result of the calculation means. The first control means for moving the locus so as to satisfy the following, the second calculation means for calculating the change in the removal amount in the in-corner portion of each processing step, and the in-corner portion based on the result of the second calculation means. 2. A wire electric discharge machine comprising: a second control means for changing and controlling machining conditions.