JPH04201118A - Electric discharge machining method - Google Patents

Abstract

PURPOSE:To increase machining speed by lowering an electrode at a high speed to a position near a work determined by a bathvoltage between the electrode and the work after the electrode is raised at high speed by a specified distance to separate it from the work. CONSTITUTION:An electrode 1 is moved forward to lower at a high jumping speed first and then lowered until a bathvoltage from a bath voltage detecting device 3 is lower than a reference value for a bathvoltage stored in a memory 14. to complete jumping 307. Then an ordinary machining is started between the electrode 1 and a work 2. Namely, after jumping control is completed, the electrode 1 can be brought to the work 2 at a high speed to a degree that the ordinary machining can be made immediately by a servo across electrodes. Thus the time needed for jumping control can be shortened and the machining speed can also be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improved electric discharge machining method that can improve machining speed.

[Prior Art] FIG. 4 is a block diagram showing a conventional electrical discharge machining apparatus for explaining a conventional electrical discharge machining method.

In the figure, 1 is an electrode, 2 is a workpiece placed opposite to the electrode 1, 3 is an electrode-to-electrode voltage detection device that detects the voltage between the electrodes 1 and the workpiece 2, and 4 is the electrode 1 and the workpiece. 2, an interpole servo control device that controls an interpole servo that moves the
Reference numeral 5 denotes a memory in which a reference voltage value is stored when the inter-electrode servo control device 4 performs inter-electrode servo, and 6 to 8 indicate the inter-electrode voltage detected by the inter-electrode voltage detection device 3 and the memory 5
A memory 9 stores a constant for calculating the number of output pulses according to the difference from the reference voltage stored in the memory, and 9 outputs a jump signal at fixed time intervals or according to the machining state of the electrode 1 and the workpiece 2. The jump starting device 10 is activated by the jump signal from the jump starting device 9, and the workpiece 2
A jump control device that controls the jump of the electrode 1 against the jump control device 11 accumulates the number of output pulses during a jump by the jump control device 10 (memory; 12 stores the number of output pulses during a jump by the jump control device 10); 13 is a memory for storing the jump amount by the jump control device 10; 20 is a jump control bag M1;
Store the end position of the jump by 0 (memory, 1
5 is a pole-to-pole servo control device 4 or a jump control device 10
(memory; 16 is an output device that outputs the number of output pulses stored in the memory 15;
Reference numeral 17 denotes a motor that is driven according to the specific cabal number output from the output device 16. The motor 17 moves the electrode 1 relative to the workpiece 2. FIG. 5 shows the flow of jump control in conventional electric discharge machining. 5 is a flowchart showing jump processing performed by the electric discharge machining apparatus shown in FIG. 4. FIG. Figure 6 is a diagram for explaining the relationship between the electrode and workpiece when jump control is performed using the conventional method, and Figure 7 is a diagram for explaining the relationship between the electrode and the workpiece when jump control is performed using the conventional method during swing machining. FIG. 3 is a diagram for explaining the relationship between an electrode and a workpiece.

First, jump control in electrical discharge machining will be explained. When performing electrical discharge machining, machining powder generated between the electrode 1 and the workpiece 2 accumulates in a specific location, which means that the electrical discharge concentrates at that location, leaving the machining location of the workpiece 2 as a discharge mark. Processing powder must be appropriately removed during processing, as it may lead to defects in the processed surface. For this reason, jump control is performed at fixed time intervals or between electrode 1 and workpiece 2 during machining.
This is done by moving the electrode 1 up and down quickly with respect to the workpiece 2, and the pumping action of this operation removes the machining powder between the two. In addition, jump control moves the electrode quickly, so electrode 1 and workpiece 2 are moved during normal machining.
A voltage is applied from a power source (not shown) between the electrodes, and the electrodes are quickly moved at a speed greater than the speed used when performing the inter-electrode servo, which moves the electrode 1 forward and backward using the inter-electrode voltage, thereby causing a pump action. It is something.

The movement of the electrode in the jump control according to a specific conventional method will be explained using FIG. 6. First.

As shown in FIG. 6a, the jump operation is activated at the jump start position 304, and the jump operation of the electrode 1 is started. Note that 305 is processing powder generated between the electrode 1 and the workpiece 2. Next, as shown in FIG. 6, the electrode 1 is raised and retreated from the workpiece 2 by a jump amount 306 at a high jump speed. Subsequently, the electrode 1 is moved downward and forward at a high jump speed to the jump end position 4°9, and the jump is completed (FIG. 6C). Jump end position 40
9 is the jump start position 3 by a preset amount 408
It will be before 04. Then, as shown in Figure 6d,
The electrode 1 is lowered from the jump end position 409 at a slow speed that performs inter-mole servo, and when the distance between the electrode 1 and the workpiece 2 reaches a predetermined distance, normal machining is started.

Next, jump control during swing machining in which the electrode 1 is moved while drawing a certain figure in a plane perpendicular to the direction in which the electrode 1 and the workpiece 20 face each other, and machining is performed while performing machining servo. This will be explained using figures. The jump control in this case also moves the electrode 1 backward and forward in the direction in which the electrode 1 and the workpiece 2 are opposed to each other. That is, as shown in FIG. 7a, the electrode 1
Draw a circular figure 505 in a plane perpendicular to the facing direction 504 with the workpiece 2, and perform machining while performing the gap servo.Then, as shown in Figure 7, jump starts. Jump activation occurs at position 406, and jump control is started. In this jump operation, electrode 1 moves upward and returns to the center of one figure 505 at a high jump speed. After that, as shown in FIG. As shown in C, the electrode 1 is lowered at a high jump speed to a jump end position 409 that is a preset amount 408 before the jump start position 406.
is lowered in the direction opposite to the workpiece 2 at a slow speed that performs inter-mole servo, and swing machining is started.

Jump control is performed in this manner.Next, jump control in the conventional method will be explained using the flowchart shown in FIG.

First, a state in which there is no jump signal and normal machining is being performed will be explained. During machining, the inter-electrode voltage detection device 3 detects the inter-electrode voltage between the electrode l and the workpiece 2 (step 1).
01). The inter-electrode servo control device 4 is connected to the inter-electrode voltage detection device 3.
Compare the electrode-to-electrode voltage detected with the set reference voltage preset in the memory 5, and calculate the difference depending on the position of the electrode 1 or the time since the short circuit occurred between the electrode 1 and the workpiece 2. and a constant stored in the selected memory 6 to 8 (step 102), and the resulting value is output as the number of output pulses to the memory 15 and stored (step 103). Thereafter, the output device 16 outputs the number of output pulses stored in the memory 15 to the motor 17 at fixed time intervals, the motor 17 is driven, and the lowering of the electrode 1 causes the voltage between the electrodes 1 and the workpiece 2 to rise. Therefore, work 2
processing is performed.

Next, the jump starting device 9 outputs a jump signal to the gap servo control device 4 and the jump control device 10 at regular intervals or depending on the state of the gap between the electrode 1 and the workpiece 2 (step 117). Then, the presence or absence of this jump signal is determined (step 106), and the jump starting device 9
If there is a jump signal from
If not, the normal machining operations of steps 101 to 104 described above are performed. That is, if there is a jump signal, the jump starting device 9 causes the interpolar servo control device 4 to stop setting the number of output pulses to the memory 15, and the jump control device 10 is activated. In the jump control device 10, it is determined whether or not the lifting of the jump is completed (step 107).
, if the lifting is not completed, the number of pulses corresponding to the jump speed preset in the memory 12 is added to the memory 11 to determine the amount of retraction of the jump, that is, the amount of lifting of the rise of the electrode 1 (step 108), step In step 109, the value of the output pulse number of the memory 12 is assigned a sign and stored in the memory 15 so that the motor 17 is operated so that the electrode l is retracted, and in step 110, the output device 16 is
outputs the number of output pulses from the memory 15 to the motor 17 at fixed time intervals, and by making the judgment in step 107, the value in the memory 11 where the number of output pulses is integrated matches the jump amount stored in the memory 13. Continue this process until. The state at this time is shown in Figure 6.

Thereafter, in step 107, when the value in memory 11 exceeds the value in memory 13, step 202 occurs. That is, in step 202, it is determined whether the jump has ended. When the lifting of the electrode 1 is completed, the jump has not yet been completed, so the process moves to step 201. Here, the jump control device 10 subtracts the number of pulses corresponding to the jump speed of the memory 12 from the memory 11 in step 2.
01), in step 112, the value of the output pulse number of the memory 12 is assigned a sign and stored in the memory 15 so that the motor 17 is operated so that the electrode 1 moves forward and downward, and in step 113, the output device 16 operates the motor 17. 17, the number of output pulses from the memory 15 is outputted at regular intervals, and the electrode 1 is lowered toward the workpiece 2 at a high jump speed.

Then, the jump is ended by making the determination in step 202. In other words, the value in memory 11 is
When the jump is below the jump end position preset to 0,
The process moves to step 114. The second condition is shown in FIG. 6C.

In step 114, the jump control device 10:
A jump end signal is output to the jump starting device 9, the value in the memory 11 is cleared (step 115), and step 1
At step 16, the jump activation device 9 turns off the jump signal. Then, when the jump signal is turned off, it is determined whether or not the machining is finished (step 1ob). If the machining is not finished, it is determined that there is no jump signal in steps 117 and 106, and steps 101 to 106 are performed.
4 normal processing will be performed. The state at this time is shown in FIG. 6d.

[Problems to be solved by the invention] As described above, jump control in conventional electric discharge machining
This is done to remove processing powder between the electrode 1 and the workpiece 2. However, the time during this jump operation does not contribute in any way to the actual machining of the workpiece 2, and is wasted time. That is, jump control is performed as shown in FIGS. 6a-C, and during the jump operation, the electrode 1 is moved at a high Young's speed.
Preset distance 408 from jump start position 304
From the front jump end position 408, the electrode 1 is moved at the normal moving speed of the inter-electrode servo, and as shown in FIG. Since the electrode 1 moves at the slow speed of the inter-electrode servo until the difference in the reference voltage becomes negative, it takes a considerable amount of time before the actual machining begins, resulting in a decrease in machining speed. was there.

In addition, if a jump operation is performed during oscillating machining as shown in Fig. 7, when the electrode 1 is lowered at the end of the jump, the height of the oscillating plane will be If the electrode 1 is not uniform, the electrode 1 may come into contact with the workpiece 2, and in this case, there is a problem in that concentrated discharge occurs at the start of machining.

This invention was made in view of the above-mentioned problems,
It is an object of the present invention to provide an electric discharge machining method that improves jump control in electric discharge machining so that the jump can be terminated at an optimal position, and that can improve machining speed.

[Means for Solving the Problems] The electrical discharge machining method according to the present invention is an electrical discharge machining method in which a workpiece is machined by an electric discharge generated by a voltage applied between an electrode and a workpiece, in which the electrode is separated from the workpiece. The method is characterized in that after the electrode is pulled up a predetermined distance at high speed, it is lowered at high speed so as to bring the electrode closer to the workpiece to a position determined based on the voltage between the electrodes and the workpiece.

[Function] In the method of this invention, in jump control, the electrode is moved at high speed to a position determined based on the inter-electrode voltage between the electrode and the workpiece. An embodiment of the electrical discharge machining method will be described with reference to the drawings.

FIG. 1 is a block diagram showing an electric discharge machining apparatus for explaining an electric discharge machining method according to an embodiment of the present invention. In the figure, 14 is a memory that stores the reference value of the voltage between the electrode 1 and the workpiece 2, which is used to determine the end of the jump operation, and the other configuration is the same as that of the conventional device shown in FIG. Since it is the same as that, the same number will be given and the explanation will be omitted.

FIG. 2 is a flowchart showing the flow of jump control in this embodiment. Also, Figure 3.

FIG. 22 is a diagram for explaining the relationship between the electrode and the workpiece when jump control is performed by the method of the second embodiment.

The movement of the two poles in the jump control according to a specific method of an embodiment of the present invention will be explained with reference to FIG. First, as shown in FIG. 3a, a jump operation is activated at a jump start position 304, and the jump operation of the electrode 1 is started. Next, as shown in Figure 3, jump amount 3
The electrode 1 is raised and retreated from the workpiece 2 by 06 at a high jump speed. The process up to this point is the same as the conventional one shown in FIGS. 6a and 6b.

Subsequently, electrode 1 is moved downward and forward at a high jump speed,
The voltage between the electrodes from the voltage between electrodes 3 is lower than the reference value of the voltage between the electrodes stored in advance in the memory 14 (FIG. 3C), and the jump is completed. This is the end position. Thereafter, normal machining is started between the electrode 1 and the workpiece 2.

Next, jump control in the method of the embodiment will be explained using the flowchart shown in FIG.

In the method of this embodiment, the only difference is the determination of the end of jump (step 111) from steps 202 and 201 of the conventional flowchart shown in FIG. The explanation will be omitted.

That is, by making the determination in step 107,
The value in memory 11 where the number of output pulses has been integrated is stored in memory 13.
The electrode 1 is pulled up until it matches the jump amount stored in . Thereafter, in step 107, if the value in memory 11 exceeds the value in memory 13, step 1
It becomes 11.

That is, in step 111, it is determined whether the jump has ended. When the lifting of the electrode 1 is completed, the jump is not completed, so the process moves to step 112.

Here, the jump control device 10 assigns the number of pulses corresponding to the jump speed of the memory 12 to the value 1 of the output pulse number of the memory 12 so that the motor 17 operates so that the electrode l advances and descends. and stored in the memory 15, and in step 113, the output device 16 outputs the data to the motor 17 in the memory 15.
5 output pulses are output at fixed time intervals, and the electrode 1 is lowered toward the workpiece 2 at a high jump speed. At the same time, in step 111, it is determined whether the voltage between the electrodes detected by the voltage detection device 3 in the jump control device 10 has become lower than the reference value of the voltage between the electrodes for terminating the jump stored in the memory 14. If the jump is low, it is determined that the jump is over, and the step
The process then moves to step 114, and thereafter the operation is similar to that of the conventional method.

By doing this, when the jump control is finished, the electrode 1 and the workpiece 2 can be brought close enough to each other at a high speed that normal machining can be performed immediately using the gap servo, so the time required for the jump control can be shortened. This means that the machining speed can be improved.

Furthermore, even if jump control according to the method of this embodiment is performed when performing the swing machining shown in FIG. Therefore, electrode 1 at high jump speed
The movement of can be stopped before electrode 1 and workpiece 2 come into contact,
This eliminates the problems encountered with conventional methods.

In the above-described embodiment, the end of the jump is determined based on whether or not the detected voltage between electrodes has become lower than the reference value of the voltage stored in the memory 14, but the present invention However, the present invention is not limited to this, and it may be determined that the jump has ended when the detected inter-electrode voltage is below a preset voltage and continues for a predetermined period of time. Furthermore, the voltage between electrodes may be used to determine the end of a jump.

[Effects of the Invention] As described above, according to the method of the present invention, in the electrical discharge machining method in which a workpiece is machined by electric discharge generated by a voltage applied between an electrode and a workpiece, high-speed processing is performed to separate the electrode from the workpiece. After pulling up the specified distance with ! The electrode is pulled down at high speed to bring it closer to the workpiece to a position determined based on the voltage between the electrode and the workpiece, increasing the range in which the electrode can move at high speed during jump control, and immediately returning to normal machining. This has the effect of improving the machining speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an electric discharge machining apparatus for explaining an electric discharge machining method according to an embodiment of the present invention, FIG. 2 is a flowchart showing the flow of jump control in this embodiment, and FIG. , a diagram for explaining the relationship between the electrode and the workpiece when jump control is performed by this embodiment method, and FIG. 4 is a block diagram showing a conventional electrical discharge machining apparatus for explaining the conventional electrical discharge machining method. Fig. 5 is a flowchart showing the flow of jump control by conventional electric discharge machining, Fig. 6 is a diagram for explaining the relationship between the electrode and the workpiece when jump control is performed by the conventional method, and Fig. 7 FIG. 2 is a diagram for explaining the relationship between the electrode and the workpiece when the jump control of the conventional method is performed during swing machining. In the figure, ■ is an electrode, 2 is a workpiece, 3 is a voltage detection device between electrodes,
Reference numeral 4 designates an interpolation servo control device, 5 to 8 a memo 1, 9 a jump starting device, 10 a jump control device, 11 to 14 a memory, 16 an output device, and 17 a motor. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Claims] In an electric discharge machining method for machining the workpiece by electric discharge generated by a voltage applied between an electrode and the workpiece, the electrode is pulled up a predetermined distance at high speed so as to be separated from the workpiece, and then the An electric discharge machining method characterized by lowering the electrode at high speed so as to bring it closer to the workpiece to a position determined based on the inter-electrode voltage between the electrode and the workpiece.