JPH06126540A - Method and apparatus for electric discharge machining - Google Patents

Abstract

PURPOSE:To reduce a hunting amount for enabling high accuracy electric discharge machining by gasping previously a region gap situation before a swing working process in a region from gap data received in a memory in the next turning-around time to set an optimum swing speed corresponding to the gap situation. CONSTITUTION:A position confirming part 6 in the next swing pattern turning- around time receives the information from a motor control section to confirm the present position of an electrode 1 and read gap data corresponding to an address of the confirmed position region out of a memory 5 and supply them to a speed setting section 7. The speed setting section 7 refers to a speed table 8 having the gap data read out before one turning-around of the region stored in the memory 5 and the relation between the gap data and swing speed tabled to set the swing speed corresponding to the gap data read out of the memory and output it as the swing speed data to the motor control section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining method and apparatus, and more particularly to an electric discharge machining method and apparatus for setting an optimum rocking speed corresponding to a machining area.

[0002]

2. Description of the Related Art During die-sinking electrical discharge machining, a machining electrode is oscillated with respect to a workpiece to be machined so that a concave portion having a predetermined shape is formed by electric discharge or the inner surface of a hole is subjected to electrical discharge machining in a predetermined shape. In so-called rocking type electric discharge machining, by using an electrode having a desired machining shape, machining having a shape similar to the electrode shape can be performed. The details of such a swing type electric discharge machining method are disclosed in Japanese Patent Publication No. 55-16773.

The swinging of the electrodes in this type of electric discharge machining is usually performed by orbiting in a simple pattern such as a square or a circle. On the other hand, there is also proposed a technique of using a voltage between electrodes and a work as a reference for determining the swing speed. This technology
The swing speed is controlled in real time according to the voltage between contacts.

[0004]

As described above, in the conventional swing-type electric discharge machining, since the high precision machining is performed, the inter-electrode voltage between the electrode and the work is detected, and the detected inter-electrode voltage is detected. Control is performed so that the swing speed is low when the voltage is low and high when the voltage between contacts is high.

However, the determination of the swing speed is as follows.
Since the swing speed is determined based on the gap data obtained at the present time, it takes electrical delay or mechanical delay for the determined swing speed command to be transmitted to the electrode movement via the motor. There is a problem that a predetermined time is required, a time delay occurs, and it is not possible to provide an optimum swing speed at the instant of machining, that is, in each machining region. For example, when the electrode moves toward the work, the swing speed is set to a high speed because the gap is wide. This high-speed movement is maintained until the electrode approaches the work and a drop in the voltage between electrodes is detected. When the electrode and the workpiece approach each other, the voltage between the electrodes decreases, so that the rocking speed decreases. However, since the deceleration takes time due to the time delay, the electrode comes into contact with the work and then retracts from the work. This withdrawal is performed until the voltage between the electrodes rises and the open state is detected, but normally when the electrode and the work are separated, open and short circuits are repeated due to chips and the like mixed in the working fluid, resulting in an indeterminate state. Therefore, the so-called hunting phenomenon occurs in which the electrodes repeatedly move forward and backward at high speed. As a result, in the region of this state, the processing does not proceed, resulting in not only a dead time but also an unprocessed residue, resulting in a decrease in the processing efficiency.

Therefore, an object of the present invention is to provide an electric discharge machining method and apparatus capable of setting an optimum rocking speed according to a machining area and enabling highly accurate electric discharge machining.

[0007]

In order to solve the above-mentioned problems, an electric discharge machining method and apparatus according to the present invention are provided in an electric discharge machining method in which machining is performed while performing an oscillating motion, and gap data between an electrode and a work and Correspondence table with suitable swing speed is registered in advance, the circuit of the swing pattern is divided into multiple areas, the gap data for each of the divided areas is detected and stored in the memory, and the swing of the next cycle is performed. When processing,
The gap data of the area is detected for each of the divided areas, an average value of the gap data and the gap data of the area stored in the memory is calculated, and updated and stored in the memory. It is configured to read the stored gap data and perform rocking machining of the area at a rocking speed corresponding to the gap data registered in advance in the correspondence table.

Further, the electric discharge machining apparatus according to the present invention, in the electric discharge machining apparatus which performs machining while performing a swing operation, stores a correspondence table of gap data between the electrode and the work and a swing speed suitable for the first data. Means, second means for storing the position of each area of the peripheral circuit of the swing pattern divided into a plurality of areas, third means for detecting gap data during swing processing, and the third means. The gap data detected by the means is stored in the memory for each of the divided areas, and the gap data for each of the divided areas detected by the third means and the memory are stored in the memory at the time of swing machining in the next round. Fourth means for calculating an average value with the area gap data and updating and storing it in the memory, and fifth means for judging in which area of the plurality of divided areas the current position of the electrode exists. And sixth means for reading the gap data of the region determined by the fifth means from the memory of the fourth means, and calling and setting the rocking speed suitable for the gap data from the first means. It is configured with.

[0009]

According to the present invention, the gap data between the electrode and the work obtained by the orbiting of the electrode is stored in the memory, and at the time of the next orbiting, the gap data stored in the memory is stored in a certain area. Prior to the rocking machining process, the gap condition of the region is grasped in advance, and the optimum rocking speed is set according to the gap condition, thereby enabling high-precision machining with a small amount of hunting.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a diagram showing a device configuration example for realizing an embodiment of a method for controlling electric discharge machining according to the present invention.
FIG. 2 shows a state in which the peripheral circuit of the square swing pattern in this embodiment is divided into 12. The average value of the inter-electrode voltage between the electrode and the work is obtained for each divided area and stored in the memory. Thus, for example, a weighted average calculation is performed with the previous data for each divided area of the swing pattern circuit, and the data is stored in the memory as gap data.

A discharge voltage for electric discharge machining is applied between the electrode 1 and the work (workpiece) 2 from a voltage source (not shown), and the gap voltage is detected between the electrodes. Detected by the unit 3. The calculation unit 4 performs a weighted average of the voltage between contacts detected by the voltage between contacts detection unit 3 and the previous calculation result data (gap data) in that area. All the gap data for all the divided areas of the oscillation pattern circuit are stored in the memory 5.

The position confirmation unit 6 receives information from a motor control unit (not shown) at the time of the next orbital swing pattern circulation, confirms the current position of the electrode, and determines the swing pattern (trajectory) of the electrode. It is confirmed which of the divided areas in FIG. 2 the position is located in, and the gap data corresponding to the address of the confirmed position area is read from the memory 5 and supplied to the speed setting unit 7. The speed setting unit 7 refers to the speed table 8 in which the gap data for one revolution before the relevant region stored in the memory 5 is read, and the relationship between the gap data and the swing speed is tabulated, The rocking speed corresponding to the gap data read from the memory 5 is set and output to the motor control unit as rocking speed data.

FIG. 3 is a block diagram embodying an embodiment of the present invention. The feed motors 14X, 14Y and 14 in the X, Y and Z directions are driven by a drive signal from the motor drive unit 101 controlled by the motor control unit 102 of the NC unit 11.
Feed screw 15X, 15Y corresponding to each motor via Z
And 15Z are driven. The electrodes 1 are moved in the X, Y and Z directions by driving the feed screws 15X, 15Y and 15Z. The movement of the electrode includes the movement along the swing pattern. A voltage is applied between the electrode 1 and the work 2 from the machining power supply 12 to control the discharge. Further, the inter-electrode voltage between the electrode 1 and the workpiece 2 is detected by the inter-electrode voltage detecting section 3 and sent to the I / O control section 103 of the NC section 11.

The machining fluid is supplied from the machining fluid tank 20 by the pump 19 to the gap between the electrode 1 and the work 2 through the solenoid valve 17 in the jet flow passage, and the electrode 18 is penetrated by the action of the pump 18. Through the hole 1A, the machining fluid is returned to the machining fluid tank 20 through the solenoid valve 16 and the suction pipe line. I / O control unit 10 of NC unit 11
3 based on the signal from the solenoid valve control unit 13
Controls the opening and closing of the solenoid valve 16 in the suction conduit and the solenoid valve 17 in the jet conduit.

The NC unit 11 includes the motor drive unit 1 described above.
01, motor control unit 102, I / O control unit 103, and operation control unit 10 for controlling various processing conditions, operations, and the like.
4. A CPU 105 that controls the entire electric discharge machining operation based on the NC program and a memory unit 106 that stores gap data and the like to be described later are provided, and are connected via a bus BUS.

The CPU 105 designates the movement position and movement mode of the electrode 1 (movement in the machining process, the above-mentioned swinging movement, etc.) and, via the motor control unit 102 and the motor drive unit 101, the motors 14X, 14Y and 14Z. Is driven, and the machining power supply 12 is controlled via the I / O control unit 103 to supply the voltage required for discharge between the electrode 1 and the work 2.
The CPU 105 also controls the opening and closing of the solenoid valves 16 and 17 via the solenoid valve control unit 13 to adjust the supply of the working fluid. The CPU 105 has the functions of the arithmetic unit 4, the position confirmation unit 6, and the swing speed setting unit 7, and the swing speed data is stored in the memory 102A in the motor control unit 102. Further, in the memory 106, a memory M1 for storing a table including data for instructing the swing processing of an area obtained by dividing the swing pattern circulation path, and the position of the current divided area (current area) are temporarily stored. Memory M to store
2. Memory M3 for storing the average inter-electrode voltage of the current area, memory M for storing the gap data of the calculation result for each divided area
4. A memory M for storing a conversion table such as the swing speed table 8 of FIG. 1 showing the relationship between the voltage between contacts and the swing speed.
5. A memory M6 for storing a machining program is provided.

The processing procedure of this embodiment will be described with reference to the flow chart shown in FIG. When the process starts, the swing pattern (trajectory) is first divided and the divided area table data is stored in the memory M1 (step S1). next,
The current position of the electrode is confirmed and stored in the memory M2 (step S2), the inter-electrode voltage is detected (step S3), and the average inter-electrode voltage is obtained for each divided area (step S4). The average voltage between contacts is updated for each detected voltage between contacts and stored in the memory M3.

Next, it is judged whether or not the circuit has rotated a specified number of times, and for example, it is confirmed whether or not the swing has made one circuit from the start of processing (step S5). This confirmation is made because there is no data on the voltage between contacts unless it has completed at least one round. Step S
If it is not the specified number of turns in 5, the process returns to step S3, and if it is turned, it is confirmed whether or not the electrode has moved to the next region (step S6). If it has not moved to the next area, the process returns to step S3. If it has moved, the rocking speed is obtained by referring to the rocking speed table M5 based on the gap data stored in the memory M4 (step S7). ). Based on the swing speed, necessary command data is sent from the memory 102A of the motor control unit 102 to the swing speed setting unit 7 (step S8). Then, the memory M
3, the average inter-electrode voltage obtained by the random calculation and the previous data of the memory M4 are functionally calculated (for example, a weighted average), and are updated in the memory M4.
Is cleared (step S9).

[0019]

As described above, in the electric discharge machining method and apparatus according to the present invention, the gap data between the electrode and the work obtained by the oscillating orbiting of the electrode is stored in the memory, and the next oscillating orbiting is performed. Since the gap situation of a certain area is grasped in advance from the gap data stored in the memory before the swing machining process of a certain area, the optimum swing speed is set according to the gap situation. The hunting amount can be reduced and the processing speed can be improved.

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram for realizing an embodiment of an electric discharge machining method according to the present invention.

FIG. 2 is a diagram showing an example of a swing pattern (trajectory) of an electrode in an example of the present invention.

FIG. 3 is a specific configuration diagram for realizing an embodiment of the electric discharge machining method and apparatus according to the present invention.

FIG. 4 is a flowchart showing a processing procedure in the embodiment of FIG.

[Explanation of symbols]

 1 Electrode 2 Work 3 Inter-electrode voltage detection unit 4 Calculation unit 5 Gap data memory 6 Position confirmation unit 7 Swing speed setting unit 8 Swing speed conversion table 11 NC unit 12 Processing power supply 13 Solenoid valve control unit 14X, 14Y, 14Z Motor 15X, 15Y, 15Z Feed screw 16, 17 Solenoid valve 18, 19 Pump 20 Working fluid tank 101 Motor drive unit 102 Motor control unit 102A Swing speed storage memory 103 I / O control unit 104 Operation control unit 105 CPU 106 Memory unit

Claims (2)

[Claims] 1. In an electric discharge machining method in which machining is performed while performing an oscillating operation, a correspondence table of gap data between an electrode and a work and an oscillating speed suitable for the data is registered in advance, and a plurality of oscillating pattern peripheral circuits are provided. Of the divided areas, the gap data for each of the divided areas is detected and stored in the memory, and the gap data of the area is detected for each of the divided areas at the time of the oscillating processing in the next round. The average value with the gap data of the area stored in the memory is calculated and updated and stored in the memory, the gap data stored in the memory of the area is read, and the gap data registered in advance in the correspondence table is used. A spark erosion machining method is characterized in that the oscillating machining of the region is performed at a corresponding oscillating velocity. 2. An electric discharge machining apparatus for machining while performing a swing motion, comprising: first means for storing a correspondence table of gap data between an electrode and a work and a swing speed suitable for the gap data; and a plurality of regions. Second means for storing the position of each area of the peripheral circuit of the swing pattern divided into two, third means for detecting gap data during swing machining, and gap data detected by the third means Is stored in the memory for each of the divided areas, and an average of the gap data of each of the divided areas detected by the third means at the time of swing machining in the next round and the gap data of the area stored in the memory. Fourth means for calculating a value and updating and storing it in the memory; fifth means for determining in which area of the plurality of divided areas the current position of the electrode exists; Memory of From the first means to read the gap data of the area determined by the fifth means, and to set the rocking speed suitable for the gap data from the first means. Electric discharge machine.