JP2000153409A - Jump control method and device for electric discharge machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically set a jump period and a jump distance for maximizing electric discharge machining efficiency. SOLUTION: In this electric discharge machine, a workpiece 2 is electrically discharge machined by applying pulse voltage across poles of an electrode 1 and the workpiece 2, also the electrode 1 decides whether machining is in an electric discharge machining process or in a jump action process when jump action is performed in the electrode 1 in accordance with jump requirement. When the electric discharge machining process is decided, a number of effective electric discharge pulses is counted in each prescribed sampling period, and the timing commanding jump requirement is decided to be based on the number of the effective electric discharge pulses in each counted sampling period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jump control method and apparatus for an electric discharge machine, and more particularly to a jump control method for an electric discharge machine which automatically determines a jump period and a jump distance of an electrode so as to maximize machining efficiency. And equipment.

[0002]

2. Description of the Related Art In an electric discharge machine, when electric discharge machining is continuously performed, machining waste (sludge) accumulates in a machining gap and machining defects occur. In order to prevent this machining failure, the electric discharge machine according to the prior art is provided with a machining fluid supply nozzle, discharges machining fluid from the nozzle toward a machining gap, and performs electrical discharge machining while removing machining chips. Further, in order to prevent the above-mentioned machining failure, the electric discharge machine according to the prior art interrupts the electric discharge machining, separates the electrode from the workpiece by a predetermined jump period for a short time by a predetermined jump distance (jumps), and thereafter causes the electrode to move. The so-called jump control for resuming electric discharge machining by approaching the workpiece again is performed. The machining waste is discharged from the machining gap by the pumping action of the machining fluid generated in the machining gap during the jump operation, and damage to the electrodes and the workpiece due to abnormal discharge is prevented. In such a conventional jump control, the setting of the jump cycle and the jump distance is based on the experience of the operator.

In general, in the jump control according to the prior art, the jump distance is increased as the machining depth of the work is increased, and the jump cycle is shortened as the machining speed is increased. To ensure stable processing.

The electric discharge machining apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 6-126534 obtains a total current for each jump cycle, controls the supply of an optimum machining current according to a change in machining state based on the total current, and performs machining. By automatically setting at least one of a required jump time and a jump distance as a jump operation in accordance with a change in the amount of generated debris, stabilization of processing, improvement of processing speed and improvement of processing accuracy are achieved.

A jump control method of an electric discharge machine disclosed in Japanese Patent Application Laid-Open No. 2-303720 discloses a method of automatically setting a jump cycle and a jump distance by fuzzy control in accordance with a discharge state, thereby reducing machining speed and machining accuracy. It is intended to improve. The electric discharge machining control method disclosed in Japanese Patent Application Laid-Open No. H10-309630 is to automatically set a jump distance and a jump speed by fuzzy inference from data of an electrode discharge area and a machining depth at a machining position and start a jump operation. .

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Although the control of the jump distance in accordance with the machining area and the machining depth of the work and the control of the jump cycle in accordance with the machining speed are performed in the 9630 publication, since the machining speed changes depending on the discharge area of the electrode, the jump cycle is controlled. Control becomes incomplete, and there arises a problem that machining defects due to machining chips occur and machining becomes unstable.

Further, Japanese Patent Laid-Open Publication No. 6-126534,
Japanese Unexamined Patent Publication No. Hei 2-303720 discloses a technique for improving the processing speed and the processing accuracy by focusing on the processing speed and the processing accuracy, and discloses a technique for determining a jump period and a jump distance of an electrode so as to maximize the processing efficiency. Absent.

Therefore, the present invention solves the above problems, and automatically sets the electrode jump period and the jump distance without considering the machining depth of the workpiece and the discharge area of the electrode. It is an object of the present invention to provide a jump control method and apparatus of an electric discharge machine for preventing a defect and performing stable machining. Another object of the present invention is to provide a jump control method and apparatus for an electric discharge machine which solves the above-mentioned problem and automatically sets a jump period and a jump distance of an electrode so as to maximize machining efficiency. I do.

[0009]

According to the present invention, there is provided a jump control method for an electric discharge machine according to the present invention, wherein a pulse voltage is applied between a pole between an electrode and a work to perform electric discharge machining on the work, and a jump request. In the jump control method of the electric discharge machine for causing the electrode to perform a jump operation according to the following, it is determined whether the electrode is an electric discharge machining process or the jump operation process, and when the electrode is determined to be an electric discharge machining process, Count the number of effective discharge pulses of the pulse voltage applied during each predetermined sampling period, based on the counted number of effective discharge pulses per sampling period,
A timing for instructing the jump request is set.

In the above-described jump control method for an electric discharge machine, the number of effective discharge pulses for each predetermined sampling period in each jump period is counted, and a predetermined number of effective discharge pulses are counted based on the number of effective discharge pulses counted for each sampling period. Calculate the average number of effective discharge pulses in the sampling cycle,
Based on the average number of effective discharge pulses in the previous sampling cycle and the average number of effective discharge pulses in the current sampling cycle, the timing for instructing the jump request is set. In the jump control method of the electric discharge machine,
The present average effective discharge pulse number is compared with the previous average effective discharge pulse number, and when the current average effective discharge pulse number is larger than the previous average effective discharge pulse number, the timing of instructing the jump request is delayed by a predetermined time. When the current average effective discharge pulse number is smaller than the previous average effective discharge pulse number, the timing for instructing the jump request is set earlier by a predetermined time.

In the above-described jump control method for an electric discharge machine, a deviation value of the number of effective discharge pulses for each sampling period is calculated based on the number of effective discharge pulses counted for each sampling period, and the calculated deviation value is a threshold value. If it is larger, the timing for instructing the jump request is set to be earlier by a predetermined time. In the jump control method for an electric discharge machine, the deviation value is a variation coefficient.

In the above-described jump control method for an electric discharge machine, the number of effective discharge pulses in each predetermined sampling cycle in each jump cycle is counted, and the counted number of effective discharge pulses, the required jump time in the jump cycle, and the discharge in the jump cycle are counted. The processing efficiency is calculated from the processing time, and the time at which the jump request is commanded is set by comparing the calculated processing efficiency with the previous processing efficiency.

In the above-described jump control method for an electric discharge machine, the first maximum machining efficiency in a first jump cycle when the electrode performs the jump operation at a preset first jump distance; A second maximum machining efficiency in a second jump cycle when the jump operation is performed at a second jump distance obtained by adding or subtracting a predetermined distance from one jump distance is calculated, and the first maximum machining efficiency and the second maximum machining efficiency are calculated. The jump distance of the electrode is set by comparison.

In the jump control method for an electric discharge machine, the number of effective discharge pulses is obtained by subtracting the number of defective pulses and the number of short pulses from the number of all output pulses of the pulse voltage applied between the gaps. is there. A jump control apparatus for an electric discharge machine according to the present invention, which achieves the above object, discharges the work by applying a pulse voltage between the electrode and the work, and performs a jump operation on the electrode in response to a jump request. In the jump control device of the electric discharge machine to be performed, a gap state detecting means for determining whether the electrode is the electrical discharge machining step or the jump operation step, and the electrode is determined to be the electrical discharge machining step by the gap state detecting means. In this case, there is provided an effective discharge counter for counting the number of effective discharge pulses of the pulse voltage applied to the gap at every predetermined sampling period, and jump time setting means for setting a time for instructing the jump request. It is characterized by.

In the jump control device of the electric discharge machine, the number of effective discharge pulses for each predetermined sampling cycle in each jump cycle is counted, and a predetermined number of effective discharge pulses are counted based on the number of effective discharge pulses counted for each sampling cycle. The jump timing setting means further includes an average value calculating means for calculating an average effective discharge pulse number for each sampling cycle, wherein the jump time setting means calculates an average effective discharge pulse number in a previous sampling cycle and an average effective discharge pulse number in a current sampling cycle. Is set based on the timing at which the jump request is issued.

In the jump control apparatus for an electric discharge machine, the jump time setting means compares the current average effective discharge pulse number with the previous average effective discharge pulse number, and determines whether the current average effective discharge pulse number is the previous average effective discharge pulse number. When the average number of effective discharge pulses is larger than the number of effective discharge pulses, the jump request is set to be delayed by a predetermined time. When the first average number of effective discharge pulses is smaller than the second average number of effective discharge pulses, the jump request is issued. Set the timing for issuing the command to be earlier by a predetermined time.

The jump control device of the electric discharge machine further includes a deviation value calculating means for calculating a deviation value of the number of effective discharge pulses for each sampling cycle based on the number of effective discharge pulses counted for each sampling cycle. The jump timing setting means sets the timing of instructing the jump request earlier by a predetermined time when the deviation value calculated by the deviation value calculation means is larger than a threshold value.

In the jump control device for an electric discharge machine, the deviation value is a variation coefficient. In the jump control device of the electric discharge machine, the number of effective discharge pulses in each predetermined sampling cycle in each jump cycle is counted, and the counted number of effective discharge pulses, the required jump time in the jump cycle, and the electric discharge machining time in the jump cycle. The jump timing setting means instructs the jump request by comparing the machining efficiency calculated by the machining efficiency calculation means with the previous machining efficiency. Set the time.

In the above-described jump control device for an electric discharge machine, the first maximum machining efficiency in a first jump cycle when the electrode performs the jump operation at a preset first jump distance, and the electrode is controlled by the first A second maximum machining efficiency in a second jump cycle when the jump operation is performed at a second jump distance obtained by adding or subtracting a predetermined distance from one jump distance is calculated, and the first maximum machining efficiency and the second maximum machining efficiency are calculated. The apparatus further includes jump parameter setting means for setting a jump distance of the electrode by comparing.

In the jump control device for an electric discharge machine, the number of effective discharge pulses is obtained by subtracting the number of defective pulses and the number of short pulses from the number of all output pulses of the pulse voltage applied between the gaps. is there.

[0021]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic block diagram showing a first embodiment of a jump control device for an electric discharge machine according to the present invention. FIG. 1 shows a jump control device of a die sinking electric discharge machine in which a pulse voltage is applied from a machining power source 3 between a pole between an electrode 1 and a work 2 and the work 2 is machined by a discharge generated between the poles. The work 2 is placed on the XY moving table 4. The XY moving table 4 moves in the X-axis and Y-axis directions by driving the X-axis servo motor 5 and the Y-axis servo motor 6, respectively. Thereby, the work 2 is positioned in the XY axis directions. On the other hand, electrode 1
Are gripped by a main shaft (not shown), and driven by a Z-axis servomotor 7 attached to a column (not shown).
It moves with the spindle in the axial direction. Thereby, the positioning of the electrode 1 in the Z-axis direction during the non-discharge machining and the control of the gap (gap) during the electric discharge machining are performed. X
The axis servomotor 5, the Y-axis servomotor 6, and the Z-axis servomotor 7 each have an encoder (not shown), and provide a signal indicating the rotation angle of the X, Y, Z-axis motor to the servo control means 8, ie, The position signals of the electrode 1 in the X, Y, and Z axis directions are fed back.

The machining power supply 3 has a search power supply used for igniting electric discharge between the poles and a main power supply used during electric discharge machining. A pulse voltage is supplied between the electrode 1 and the work 2 in accordance with the parameters for the machining power supply such as (discharge time) and τoff (pause time). The processing control means 10 sets the XY moving table 4 on the X axis,
Control parameters for moving in the Y-axis direction are sent to the table feed control means 11, while control parameters for moving the electrode 1 in the Z-axis direction are sent to the electrode feed control means 12.

The inter-electrode state detecting means 13 determines whether the inter-electrode state between the electrode 1 and the work 2 is a state in which the discharge has not yet started after a search voltage has been applied between the electrodes from the search power supply of the machining power supply 3. Alternatively, it has a function of detecting a short-circuit state, an effective discharge state after application of a main voltage from a main power supply between poles, or an abnormal discharge state such as leakage or arc. The machining control means 10 receives the gap state signal from the gap state detection means 13 and sends the machining power parameter suitable for machining to the machining power supply 3.

The gap state detecting means 13 detects a gap state from, for example, a voltage applied between the gaps, and sends, for example, an average voltage between the gaps to the arithmetic unit 14. The arithmetic unit 14 sends a servo signal to the electrode feed control unit 12 based on the difference between the detection amount received from the gap state detection unit 13 and the target reference value received from the processing control unit 10. The electrode feed control means 12 outputs the forward / retreat amounts of the electrode 1 to the servo control means 8 based on the control parameters sent from the processing control means 10 and the servo signals sent from the calculator 14.

The data input means 15 is provided for the processing control means 10.
Is a means for inputting various data to the computer, and is composed of a keyboard, a CRT, and the like (not shown). The machining control means 10 processes machining power parameters necessary for machining the workpiece 2 based on the input data from the data input means 15 and the gap state signal received from the gap state detection means 13.
Set control parameters and target reference values for each servomotor. Further, the processing control means 10 is provided with an RS (not shown).
The processing program read by the H.232C or a floppy disk drive (FDD) can also be read for each block.

The jump control means 16 starts a jump operation of the electrode 1 in response to a jump request signal sent from the jump time setting means 31 and the abnormal machining judgment means 18. The jump timing setting means 31 is determined by the effective discharge counter 20, the average value calculation means 33 and the deviation value calculation means 35 based on the effective discharge pulse output from the gap state detection means 13 when the gap is in the effective discharge state. The jump time is set based on the jump period thus set, and a jump request signal is sent to the jump control means 16. The jump request signal is generated substantially every predetermined jump period according to the state of the gap.

The abnormal machining judging means 18 receives the count value of the abnormal discharge pulse signal indicating the abnormal state between the gaps sent from the gap state detecting means 13 to the abnormal discharge counter 19 and counting the count value. Is exceeded, the gap is determined to be abnormal, and a jump request signal is sent to the jump control means 16.

The effective discharge counter 20 counts the effective discharge pulses output from the gap state detecting means 13 at a predetermined sampling cycle, for example, every 10 ms, and counts the counted value. The average value calculating means 33 and the deviation value calculating means 35 Output to

The jump time setting means 31 sets the next time to instruct a jump request based on the number of effective discharge pulses for each sampling cycle counted by the effective discharge counter 20. Here, the number of effective discharge pulses is a value obtained by subtracting the number of defective pulses and the number of short pulses due to leaks, arcs, etc. from the total number of output pulses among the pulse voltages applied between the electrodes.

The average value calculating means 33 receives the count value from the effective discharge counter 20, that is, the number of effective discharge pulses every 10 ms, and counts the value every jump cycle from the start of electric discharge machining in the jump cycle to the sampling time. The number of effective discharge pulses is accumulated for each sampling cycle, and the average number of effective discharge pulses in the sampling cycle is calculated from the latest number of effective discharge pulses for a predetermined plurality of times up to the sampling time based on the accumulated number of effective discharge pulses for each sampling cycle. , The result of the calculation is set as jump cycle setting means 3
Output to 1. Specifically, the number of effective discharge pulses output from the effective discharge counter 20 every 10 ms is accumulated a predetermined number of times, for example, five times, and the number of effective discharge pulses accumulated during the 50 ms is averaged. The average number of effective discharge pulses for each sampling period, that is, every 10 ms is calculated. The latest five sampling data is used as the number of effective discharge pulses for each of the five sampling periods.

Further, the jump time setting means 31 determines a next command for a jump request based on the average number of effective discharge pulses calculated in the previous sampling cycle and the average number of effective discharge pulses calculated in the current sampling cycle. Set. That is, the jump time setting means 31 determines that the number of times of sampling since entering the electric discharge machining process is a predetermined number of times,
For example, when the m-th cycle is reached, the average number of effective discharge pulses during the current sampling cycle is compared with the average number of effective discharge pulses during the previous sampling cycle, and the current average number of effective discharge pulses is calculated as the previous average number of effective discharge pulses. When greater than
The machining state is considered to be good, and the next command for a jump request is set to be later than the initial set value by a predetermined time.
That is, the setting value of the jump cycle is set to be longer than the initial setting value by a predetermined time.

On the other hand, when the present average effective discharge pulse number is smaller than the previous average effective discharge pulse number, the jump time setting means 31 regards the machining state as defective and sets the next time when a jump request is issued to the initial setting value. It is set to be earlier by a predetermined time. That is, the setting value of the jump cycle is set shorter than the initial setting value by a predetermined time. Deviation calculation means 35
Is the count value from the effective discharge counter 20, that is, 1
Receives the number of effective discharge pulses every 0 ms, accumulates the number of effective discharge pulses counted from the start of electric discharge machining in the jump cycle to the sampling time for each jump cycle, and accumulates the number of effective discharge pulses for each sampling cycle. Based on the calculated average number of effective discharge pulses for a plurality of times up to the sampling time, a deviation value of the number of effective discharge pulses in the sampling cycle is calculated, and the calculation result is output to the jump time setting means 31.

When the deviation value output from the deviation value calculating means 35 is larger than the threshold value, the jump time setting means 31
Next, the timing of instructing the jump request is set to be earlier by a predetermined time. That is, the set value of the jump cycle is shortened by a predetermined time. The deviation value calculating means 35 obtains a coefficient of variation as a deviation value using sampling data X _j (j = 1 to n) of the number of effective discharge pulses output from the effective discharge counter 20. This coefficient of variation is calculated using statistics as follows.

First, the variation S _X is calculated by the following equation (1). S _X = Σ (X _j −X _av ) ² (1) Here, X _av is an average value of the sampling data X _j of the number of effective discharge pulses of n times. Therefore, the variation S _X is j = 1 of the deviation (X _j −X _av ) indicating the dispersion from the average value.
From j to j = n.

Next, the variance and standard deviation are calculated by the following equation (2).
It is calculated by (3). Variance = fluctuation / number = S _x / n (2) Standard deviation = SQR variance = √ (S _x / n) (3) Variation coefficient C _x = standard deviation / average from the above equations (2) and (3) The value is calculated by the following equation (4).

C _x = √ (S _x / n) / X _av (4) The variation coefficient C _x thus obtained indicates the degree of dispersion from the average value of the sampling data. Therefore, in the present invention, this time variation coefficient as a deviation value C _x is greater than a predetermined threshold value, there is a possibility to shift to the arc discharge, then sets the timing for instructing the jump requested to faster predetermined time Prevents arcing.

The jump parameter setting means 24 receives a jump parameter as an initial setting value, for example, data of a jump cycle and a jump distance from the machining condition setting means 10 before the start of electric discharge machining of the predetermined work 2, and after the start of electric discharge machining. The data of the jump period and the jump distance are received from the machining efficiency calculating means 23 and these data are output to the jump control means 16.

The electric discharge machining control apparatus 100 for performing the functions of the above-described means includes, for example, a CPU, a ROM, a RAM, a B (battery backup) RAM, various input interfaces and various outputs, which are interconnected by a bidirectional bus (not shown). It consists of a microcomputer system with an interface. A keyboard and an A / D converter are connected to the input interface. A /
For example, an analog voltage between the poles is input to the D converter at a low level via an attenuator, and is converted into digital data. A CRT, a printer, a D / A converter, and the like are connected to the output interface.

Next, the jump control performed by the jump control device of the electric discharge machine according to the first embodiment of the present invention shown in FIG. 1 will be described below. FIG. 2 is a flowchart showing a main routine of jump control according to the present invention. Hereinafter, description will be made with reference to FIG. 1 and FIG. This routine decodes a machining program read by the machining condition setting means 10 in response to a start command, and performs necessary preprocessing such as setting parameters for the machining power supply 3, the table feed control means 11, and the electrode feed control means 12. 9 is a partial flow showing the control of the main part of the electric discharge machining after the machining from the start of machining to the end of machining. Although not explicitly specified in the flow, a loop portion in the flow is executed at predetermined intervals, for example, at intervals of 10 ms.

First, in step 201, a machining flag is set.
Set EDFLG to 1 and jump flag JPFLG to 0. In step 202, it is determined whether or not a jump operation is being performed by the flag JPFLG. If JPFLG = 1, it is determined that the jump operation is being performed, and the process proceeds to step 209. If JPFLG = 0, it is determined that the jump operation is completed, and the process proceeds to step 203. . The jump control in step 209 will be described later with reference to FIG.

In step 203, it is determined whether or not a jump request command has been input from the jump time setting means 31 or the abnormal machining determination means 18 to the jump control means 16. If the determination result is YES, the flow advances to step 206 to discharge. The machining flag EDFLG is reset to 0, and then the flag JPFLG indicating that a jump operation is being performed is set to 1 in step 207.
After that, the process proceeds to step 208 to perform jump setting. The jump setting in step 208 will be described later with reference to FIG. On the other hand, if the decision result in the step 203 is NO, the process proceeds to a step 204 to execute the electrode feed control. FIG. 3 shows the electrode feed control in step 204.
This will be described later with reference to FIG.

In step 205, it is determined from the position in the Z-axis direction of the electrode 1 whether or not the processing of the workpiece 2 has been completed. When the electrode 1 has reached a predetermined processing depth, it is determined that the processing has been completed. When the electrode 1 has not reached the predetermined processing depth, it is determined that the processing has not been completed, and Step 20 is performed.
Return to 2. In step 210, it is determined whether or not the electrode 1 has completed the jump operation and has reached the jump end position.
If the determination result is YES, the process proceeds to step 211 to reset the jumping flag JPFLG to 0, and then proceeds to step 212 to write and register the measured required jump time in, for example, RAM, and then proceed to step 213. If the decision result in the step 210 is NO, a step 213 is executed.
Proceed to. After resetting the machining flag EDFLG to 1 in step 213, the process returns to step 202 and repeats the above control until the machining is completed. The determination that the electrode 1 has reached the jump end position in step 210 is performed, for example, by reading movement command data to the Z-axis servomotor 7 that moves the electrode 1 in the Z-axis direction. That is, from the generation of the jump request command, the electrode 1 is moved by a jump distance L described later.
_JMP apart in the Z-axis direction from the workpiece 2, that it has approached only work 2 jump distance L _JMP again confirmed by counting the move command and position data, performs the above determination. Next, the electrode feed control in step 204 in FIG. 2 will be described below.

FIG. 3 is a flowchart showing a subroutine of the electrode feed control of the first embodiment. This routine shows the details of step 204 in FIG. 2. In step 301, the voltage between the gaps detected by the gap state detecting means 13 is read. In step 302, the arithmetic unit 14 sends a servo signal to the electrode feed control unit 12 based on the difference between the voltage between the gaps detected by the gap state detection unit 13 and the target reference value set by the processing condition setting unit 10. The electrode feed control means 12 calculates the F based on the servo signal and the control parameter sent from the processing condition setting means 10 based on the sent difference amount.
/ B (forward / backward) and sends it to the servo control means 8. In step 303, the servo control means 8 performs an interpolation calculation to calculate the amount of movement to each axis. Step 30
At 4, the servo control means 8 drives each axis servomotor,
The positioning control of the electrode 1 is performed. Step 30
The control from 1 to step 304 may be performed in another loop (indicated by a dotted line in FIG. 3) and repeated at a speed higher than 10 ms.

In step 305, the effective discharge counter 2
The average value calculation means 33 averages the count value obtained by counting the number of effective discharge pulses output from 0 every predetermined period, for example, every 10 ms, by a plurality of latest times to calculate the average number of effective discharge pulses. In step 306, the count value, that is, the number of effective discharge pulses every 10 ms, is received from the effective discharge counter 20, and the average effective number of the latest predetermined multiple times from the start of the electric discharge machining in the electric discharge machining process to the sampling time is set every jump cycle. The number of discharge pulses is calculated, the deviation from the number of effective discharge pulses in the sampling cycle is calculated, and the calculation result is output to the jump time setting means 31.

At step 307, the deviation value calculating means 35
Judge whether the deviation value output from is larger than the threshold value,
When the result of the determination is YES, the process proceeds to step 308,
If the determination result is NO, the process proceeds to step 309. In step 308, the next instruction for a jump request is set to be earlier by a predetermined time. That is, the set value of the jump cycle is shortened by a predetermined time.

In step 309, the m-th sampling in the current jump cycle is, for example, m = 6 or m>
It is determined whether 6 or m <6, and if the result of the determination is m = 6, the process proceeds to step 310; if the result of the determination is m> 6, the process proceeds to step 314; if the result of the determination is m <6, Ends this routine. In step 310, the jump timing setting means 31 compares the previous average effective discharge pulse number with the current average effective discharge pulse number, and executes a predetermined number of times, for example, the m-th (m = 6) sampling, first sampling. The first average effective discharge pulse number calculated in the cycle is (m-1) which is one time earlier than the predetermined number m times.
When it is larger than the second average effective discharge pulse number calculated in the second sampling period, the machining state is considered to be good,
In step 311, it is set so that the timing of next instructing a jump request is delayed by a predetermined time from the initial setting value. That is, the setting value of the jump cycle is set to be longer than the initial setting value by a predetermined time.

On the other hand, in step 310, the first average effective discharge pulse number for executing the m-th (m = 6) predetermined number of samplings by the jump timing setting means 31 is (m) one before the m-th predetermined number of times. -1) If the number of times is smaller than the second average effective discharge pulse number, the machining state is regarded as defective, and in step 312, the next command for the jump request is set to be earlier than the initial set value by a predetermined time. That is, the setting value of the jump cycle is set shorter than the initial setting value by a predetermined time. If it is determined in step 310 that the first average effective discharge pulse number is equal to the second average effective discharge pulse number, the process proceeds to step 313.

In step 313, a jump request command is output from the jump time setting means 31 to the jump control means 16. Next, in step 314, the jump time setting means 31 determines that the third average effective discharge pulse number calculated in the third sampling cycle of the predetermined number n (n> m) is (n) one before the predetermined number n. -1) When it is determined that the value is larger than the fourth average effective discharge pulse number calculated in the fourth sampling period, the same processing as the processing of the set value of the jump period changed in the fourth sampling period is performed in step 315. That is, if the jump period is set longer by a predetermined time during the previous sampling, the jump period during the current sampling is also set longer by a predetermined time. The cycle is also set shorter by a predetermined time.

On the other hand, in step 314, when the third average effective discharge pulse number is smaller than the fourth average effective discharge pulse number,
The reverse processing of the processing of the set value of the jump period changed in the sampling period is performed. That is, when the jump cycle is set to be longer by a predetermined time at the time of the previous sampling, the jump cycle at the current sampling is set to be shorter by a predetermined time, and when the jump cycle is set to be shorter by the predetermined time at the last sampling, the jump at the current sampling is set. The cycle is set longer by a predetermined time. In step 314, when the first average effective discharge pulse number is equal to the second average effective discharge pulse number, the process proceeds to step 313.

FIG. 4 is a flowchart showing a jump setting subroutine of the first embodiment. The jump distance shown in FIG. 4 is set only once each time a jump operation is started by a jump request, as can be seen from FIG. Done. In step 401, the output of the movement command at the time of electric discharge machining from the electrode feed control means 12 to the servo control means 8 is temporarily stopped. In step 402, the electric discharge machining time in the machining cycle is written and registered in, for example, a RAM. In step 403, the jump distance L _JMP is set, and this routine ends.

FIG. 5 is a flowchart showing a subroutine for jump control. The jump setting subroutine shown in FIG. 5 is executed by the jump control means 16, and the jump distance L _JMP , the jump speed V _JMP and the jump acceleration / deceleration time constant T _JMP are set. The servo control means 8
Jump distance L set by jump control means 16
_JMP , jump speed V _JMP and jump acceleration / deceleration time constant T _JMP are received, and based on these, in step 501, acceleration / deceleration of the jump block is calculated. Step 5
In step 02, the interpolation of the jump block is calculated based on the acceleration / deceleration of the jump block calculated in step 501.
In step 503, feed command data is output based on the interpolation calculation in step 502, and the Z-axis drive motor 7
To control the positioning of the electrode 1 in the Z-axis direction.

FIG. 6 is a schematic block diagram showing a second embodiment of the jump control device of the electric discharge machine according to the present invention. The second embodiment shown in FIG. 6 is different from the first embodiment shown in FIG. 1 in that the jump time setting means 31 of FIG.
1 in that a filter 21, a frame filter 22, and a processing efficiency calculating means 23 are newly provided in place of the average value calculating means 33 and the deviation value calculating means 35 in FIG. The functions of these newly added units are performed by the microcomputer system described above. Next, these first
The function of each means of the second embodiment different from the embodiment will be described below.

The jump control means 16 starts a jump operation of the electrode 1 in response to a jump request signal sent from the jump time setting means 17 and the abnormal machining judgment means 18. The jump timing setting means 17 is configured to output the effective discharge counter 20 and the filter 2 based on the effective discharge pulse output from the gap state detecting means 13 when the gap is in the effective discharge state.
1, frame filter 22 and processing efficiency calculating means 23
The jump timing is set based on the jump cycle determined by the above, and a jump request signal is sent to the jump control means 16. The jump request signal is generated substantially every predetermined jump period according to the state of the gap.

The effective discharge counter 20 counts the effective discharge pulses output from the gap state detecting means 13 at a predetermined sampling period, for example, every 10 ms, and outputs the counted value to the filter 21. The filter 21 receives the count value from the effective discharge counter 20, that is, the number of effective discharge pulses every 10 ms, and outputs the count at a predetermined period, for example, 10 ms.
The average effective discharge pulse number obtained by averaging the five effective discharge pulse numbers during each time is output to the frame filter 22 and the machining efficiency calculating means 23.

The frame filter 22 outputs a frame average effective discharge pulse number obtained by averaging the average effective discharge pulse number among a plurality of frames with one jump period as one frame, to the machining efficiency calculating means 23.

The machining efficiency calculating means 23 receives the average number of effective discharge pulses from the filter 21 and the average number of frame effective discharge pulses from the frame filter 22, respectively, and calculates and calculates the processing efficiency and the average processing efficiency according to the processing described later. The data of the processing efficiency and the average processing efficiency are stored in the jump time setting means 17 and the jump parameter setting means 24.
Respectively.

Next, the jump control performed by the jump control device of the electric discharge machine according to the second embodiment of the present invention shown in FIG. 6 will be described below. The main routine of the jump control according to the second embodiment of the present invention is the same as the flowchart of the main routine of the jump control according to the first embodiment of the present invention shown in FIG. 2, except that the electrode feed control of step 204 is performed by a subroutine shown in FIG. The only difference is that the jump setting in step 208 is performed by the subroutine shown in FIG. Therefore, the electrode feed control of FIG. 7 and the jump setting of FIG. 10 according to the second embodiment will be described below.

FIG. 7 is a flowchart showing a subroutine of the electrode feed control of the second embodiment. This routine shows the details of step 204 in FIG. 2. In step 701, the voltage between the gaps detected by the gap state detection unit 13 is read. In step 702, the arithmetic unit 14 sends a servo signal to the electrode feed control unit 12 based on the difference between the voltage between the gaps detected by the gap state detection unit 13 and the target reference value set by the processing condition setting unit 10. The electrode feed control means 12 calculates the F based on the servo signal and the control parameter sent from the processing condition setting means 10 based on the sent difference amount.
/ B (forward / backward) and sends it to the servo control means 8. In step 703, the servo control means 8 performs an interpolation calculation to calculate the amount of movement to each axis. Step 70
At 4, the servo control means 8 drives each axis servomotor,
The positioning control of the electrode 1 is performed. Step 70
The control from 1 to step 704 may be performed in another loop (indicated by a dotted line in FIG. 7) and repeated at a speed higher than 10 ms.

In step 705, the effective discharge counter 2
The number of effective discharge pulses output from 0 is counted a predetermined period, for example, every 10 ms. The filter 21 reads the count value a plurality of times and averages them to calculate an effective number of effective discharge pulses. I do.
In step 706, the average number of effective discharge pulses output from the filter 21 is read by the frame filter 22, and further averaged over a plurality of frames having one jump period as one frame to calculate a frame average effective discharge pulse number. The effective discharge number frame filtering process is performed, and the calculation result is output to the machining efficiency calculation means 23.

In step 707, the processing efficiency η is calculated according to the following equation. η = ΣN _i (t) / (J _T + M _T ) (1) Here, N _i (t) indicates the count value of the average number of effective discharge pulses for each sampling period, and ΣN _i (t) indicates the current value. of the cumulative value of N _i from the discharge machining start time of the jump period T _J until the sampling timing (t), J _T denotes a jump time required in the discharge machining immediately before the jump operation of the current jump period, M _T Indicates the electric discharge machining time from the electric discharge machining start timing of this jump cycle to the sampling timing.

FIG. 8 is an explanatory diagram of a jump cycle. Horizontal axis
Represents the time t, and the vertical axis represents the electrode position L between the electrode 1 and the work 2.
You. One jump period T_JIs the jump process J_TAnd release
Electric machining process M_TIn the present invention, the jump time is set.
The time when the processing efficiency becomes maximum is determined by the setting means 17,
Outputs a jump request command to the jump control means 16
You. Jump process J_TIndicates that a jump request command is output.
Jump distance L _JOnly electrode 1 escapes from work 2
The electrode 1 is brought close to the work 2 again and electric discharge machining is resumed.
It is the time it takes to do.

Returning to FIG. In step 708, 1
The machining efficiency η calculated in step 707 is further averaged between a plurality of frames in which one jump cycle is defined as one frame to calculate an average machining efficiency η _F. In step 709, it is determined whether or not it is the machining process end time that gives the maximum machining efficiency. That is, by comparing the magnitude relation between processing efficiency computed in the previous processing cycle of this routine η _(i-1) and the processing efficiency eta computed to the current processing cycle _{(i) η (i-1} )> η _(i) , the processing efficiency has reached the maximum value, or the processing efficiency η _(i) is compared with the average processing efficiency η _F, and η
_(i) If the condition of << η _F continues, it is determined that machining should not be continued, and the process proceeds to step 710, where
At 10, a jump request command is output from the jump time setting means 17 to the jump control means 16. Step 70
If η _(i−1) ≦ η _(i) in 9, the machining efficiency has not yet reached the maximum value, so it is determined that machining should be continued, and this routine ends.

FIG. 9 is a diagram showing experimental results of the number of effective discharge pulses and machining efficiency during electric discharge machining. The horizontal axis shows the machining time with the time to start the electric discharge machining process in the jump cycle set to 0, and the vertical axis shows the effective discharge pulse number per unit time, for example, within 10 ms, and the machining efficiency. The number of effective discharge pulses per unit time indicates the machining speed. A curve 51 indicates the average effective discharge pulse number, and a curve 52 indicates the frame average effective discharge pulse number. A curve 53 indicates the processing efficiency per unit time, and a curve 54 indicates the average processing efficiency. Next, the jump setting in step 208 of FIG. 2 will be described below.

FIG. 10 is a flowchart showing a subroutine for setting a jump in the second embodiment. The setting of the jump distance shown in FIG. 10 is performed only once each time a jump operation is started by a jump request, as can be seen from FIG. Done. First, in step 1001, the electrode feed control means 1
The output of the movement command at the time of electric discharge machining from 2 to the servo control means 8 is temporarily stopped. In step 1002, the electric discharge machining time in the machining process is written and registered in, for example, a RAM. In step 1003, the jump distance evaluation flag JP
When the flag watches LFLG is 0 (NO in step 1003), or jump distance L _JMP set by the jump control means 16 is properly set, that determines whether to evaluate the jump distance L _JMP, If the result of the determination is NO, the process proceeds to step 1004. In step 1004, it is determined whether to evaluate and correct the jump distance or to check the jump distance or the like every time the machining position advances by 0.5 mm.
If it is O, it is determined that the jump distance L _JMP has been appropriately set, and the routine proceeds to step 1005, where the jump distance L _JMP is set, and this routine ends.

In step 1003, when the jump distance evaluation flag JPLFLG is checked and the flag is 1 (YES in step 1003), and it is determined that the jump distance L _JMP is to be evaluated, the flow proceeds to step 1006. In step 1006, the average processing efficiency η _{F (i-1)} calculated in the previous processing cycle and the average processing efficiency η _{F (i-2)} calculated in the processing cycle _two times before are read from the RAM. In step 1007, the magnitude relationship between these average machining efficiencies η _{F (i-1)} and η _{F (i-2)} is compared. If the determination result is NO, that is, η _{F (i-1)
When F (i-1)} ≧ η _{F (i-2)} , this routine is terminated when it is determined that the previous average machining efficiency is equal to or higher than the average machining efficiency of the previous _two times.

In step 1007, η _{F (i-1)} <η
_{In the case of F (i-2)} , it is determined that the average machining efficiency has become worse than before two times, and the process proceeds to step 1008, where the jump distance L
Back subtracted from _JMP predetermined distance α a (L _JMP-.alpha.) to jump distance L _JMP before last, and outputs a jump distance L _JMP to maximize the processing efficiency from the jump parameter setting means 24 to the jump control means 16. Then, the process proceeds to step 1009, where the jump distance evaluation flag JPLFLG is set to 0.
And the routine ends.

Further, in step 1004, if it is determined from the jump distance flag that the jump distance is to be investigated, the process proceeds to step 1010, where the current position on the Z-axis of the electrode 1 at the time when the jump request is instructed. L _JMP is _{previously stored} in the RAM as a distance to return the electrode 1 from the position in the Z-axis direction so as to separate the electrode 1 from the work 2, that is, a jump distance.
Set by adding a jump distance L _JMP predetermined distance alpha to (L _JMP + α) as a new jump distance L _JMP stored in. Then, the process proceeds to a step 1011, wherein a jump distance evaluation flag JPLFLG is set to 1, and the present routine ends.

In the above-described embodiment of setting the jump distance, an example has been described in which the respective processing efficiencies in two consecutive jump cycles are compared to set the jump distance. However, each processing efficiency in a plurality of consecutive jump cycles is set. Based on
A jump distance may be set, whereby a highly reliable jump distance can be set.

[0069]

As described above, according to the jump control method and apparatus of the electric discharge machine of the present invention, the jump period or the jump distance of the electrode can be performed without considering the machining depth of the workpiece and the discharge area of the electrode. Can be automatically set, thereby preventing processing defects due to processing waste and performing stable processing.

Further, according to the jump control method and apparatus of the electric discharge machine of the present invention, the jump cycle and the jump distance that maximize the machining efficiency can be automatically determined without depending on the experience of the operator.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a first embodiment of a jump control device of an electric discharge machine according to the present invention.

FIG. 2 is a flowchart showing a main routine of jump control according to the present invention.

FIG. 3 is a flowchart illustrating a subroutine of electrode feed control according to the first embodiment.

FIG. 4 is a flowchart illustrating a jump setting subroutine according to the first embodiment.

FIG. 5 is a flowchart showing a subroutine of jump control.

FIG. 6 is a schematic block diagram showing a second embodiment of the jump control device of the electric discharge machine according to the present invention.

FIG. 7 is a flowchart illustrating a subroutine of electrode feed control according to a second embodiment.

FIG. 8 is an explanatory diagram of a jump cycle.

FIG. 9 is a diagram showing experimental results of the number of effective discharge pulses and machining efficiency during electric discharge machining.

FIG. 10 is a flowchart illustrating a jump setting subroutine according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrode 2 ... Work 3 ... Machining power supply 4 ... XY movement table 5, 6, 7 ... X, Y, Z axis servo motor 8 ... Servo control means 10 ... Machining control means 11 ... Table feed control means 12 ... Electrode feed Control means 13 ... gap state detection means 14 ... arithmetic unit 15 ... data input means 16 ... jump control means 17, 31 ... jump time setting means 18 ... abnormal machining determination means 19 ... abnormal discharge counter 20 ... effective discharge counter 21 ... filter Reference Signs List 22 frame filter 23 machining efficiency calculating means 24 jump parameter setting means 33 average value calculating means 35 deviation value calculating means 100 electric discharge machining control device

Claims (16)

[Claims] 1. A jump control method of an electric discharge machine for applying a pulse voltage between a pole between an electrode and a work to perform electric discharge machining on the work and to cause the electrode to perform a jump operation in response to a jump request. Discriminating whether the electrode is an electric discharge machining process or the jump operation process, and when the electrode is determined to be an electric discharge machining process, counts the effective discharge pulse number of the pulse voltage applied between the electrodes at a predetermined sampling cycle. A jump control method for an electric discharge machine, wherein a timing for instructing the jump request is set based on the counted number of effective discharge pulses for each sampling period. 2. The number of effective discharge pulses for each predetermined sampling cycle in each jump cycle is counted, and the average number of effective discharge pulses in a plurality of sampling cycles is determined based on the number of effective discharge pulses counted for each sampling cycle. The electric discharge machine according to claim 1, wherein a time when the jump request is commanded is set based on an average number of effective discharge pulses in a previous sampling cycle and an average number of effective discharge pulses in a current sampling cycle. Jump control method. 3. The present average effective discharge pulse number is compared with the previous average effective discharge pulse number, and when the current average effective discharge pulse number is larger than the previous average effective discharge pulse number, the jump request is commanded. 3. The timing according to claim 2, wherein the timing is set to be delayed by a predetermined time, and when the current average effective discharge pulse number is smaller than the previous average effective discharge pulse number, the timing for instructing the jump request is set to be advanced by a predetermined time. Jump control method for electric discharge machine. 4. A method for calculating a deviation value of the number of effective discharge pulses for each of the sampling periods based on the number of effective discharge pulses counted for each of the sampling periods. 4. The jump control method for an electric discharge machine according to claim 2, wherein the instruction timing is set to be earlier by a predetermined time. 5. The jump control method for an electric discharge machine according to claim 4, wherein the deviation value is a coefficient of variation. 6. The number of effective discharge pulses for each predetermined sampling period in each jump cycle is counted, and the machining efficiency is calculated from the counted number of effective discharge pulses, the required jump time in the jump cycle, and the electric discharge machining time in the jump cycle. The jump control method for an electric discharge machine according to claim 1, wherein a timing at which the jump request is issued is set by comparing the calculated machining efficiency with a previous machining efficiency. 7. A first maximum machining efficiency in a first jump cycle when the electrode performs the jump operation at a preset first jump distance, and the electrode is adjusted by a predetermined distance to the first jump distance. By calculating a second maximum processing efficiency in a second jump cycle when the jump operation is executed at a second jump distance, and comparing the first maximum processing efficiency with the second maximum processing efficiency, the electrode jump is performed. The jump control method for an electric discharge machine according to claim 6, wherein the distance is set. 8. The method according to claim 1, wherein the number of effective discharge pulses is obtained by subtracting the number of defective pulses and the number of short pulses from the number of all output pulses of the pulse voltage applied between the electrodes. 2. The jump control method for an electric discharge machine according to claim 1. 9. A jump control device of an electric discharge machine for applying a pulse voltage between a pole between an electrode and a work to perform electric discharge machining on the work and to cause the electrode to perform a jump operation in response to a jump request. A gap state detecting means for determining whether the electrode is an electric discharge machining step or the jump operation step, and a pulse voltage applied between the gaps when the electrode is determined to be an electric discharge machining step by the gap state detecting means. A jump control device for an electric discharge machine, comprising: an effective discharge counter for counting the number of effective discharge pulses for each predetermined sampling period; and jump time setting means for setting a time for instructing the jump request. 10. The number of effective discharge pulses for each predetermined sampling cycle in each jump cycle, and an average effective discharge pulse for each of a plurality of predetermined sampling cycles based on the number of effective discharge pulses counted for each sampling cycle. Average value calculating means for calculating the jump request, based on the average number of effective discharge pulses in the previous sampling cycle and the average number of effective discharge pulses in the current sampling cycle. The jump control device for an electric discharge machine according to claim 9, wherein a timing for instructing is set. 11. The jump time setting means compares a current average effective discharge pulse number with a previous average effective discharge pulse number, and determines whether the current average effective discharge pulse number is larger than a previous average effective discharge pulse number. Setting the timing for instructing the jump request to be delayed by a predetermined time; and when the first average effective discharge pulse number is smaller than the second average effective discharge pulse number, the timing for instructing the jump request is advanced by a predetermined time. The jump control device for an electric discharge machine according to claim 10, wherein the jump control device is set as follows. 12. The jump time setting means, further comprising: a deviation value calculating means for calculating a deviation value of the number of effective discharge pulses for each sampling cycle based on the number of effective discharge pulses counted for each sampling cycle. The jump control device for an electric discharge machine according to claim 10 or 11, wherein when the deviation value calculated by the deviation value calculation means is larger than a threshold value, the timing of instructing the jump request is set to be earlier by a predetermined time. 13. The method according to claim 1, wherein the deviation value is a coefficient of variation.
3. The jump control device for an electric discharge machine according to claim 2. 14. The number of effective discharge pulses for each predetermined sampling cycle in each jump cycle is counted, and the machining efficiency is calculated from the counted number of effective discharge pulses, the required jump time in the jump cycle, and the electric discharge machining time in the jump cycle. The jump timing setting means sets the timing at which the jump request is issued by comparing the machining efficiency calculated by the machining efficiency calculation means with the previous machining efficiency. Item 10. A jump control device for an electric discharge machine according to item 9. 15. The first maximum machining efficiency in a first jump cycle when the electrode performs the jump operation at a first jump distance set in advance, and the electrode performs the first jump processing.
Calculate a second maximum machining efficiency in a second jump cycle when the jump operation is executed at a second jump distance obtained by adding or subtracting a predetermined distance from the jump distance, and compare the first maximum machining efficiency with the second maximum machining efficiency. The jump control device for an electric discharge machine according to claim 14, further comprising jump parameter setting means for setting a jump distance of the electrode. 16. The method according to claim 9, wherein the number of effective discharge pulses is obtained by subtracting the number of defective pulses and the number of short pulses from the number of all output pulses of the pulse voltage applied between the electrodes. 2. The jump control device for an electric discharge machine according to claim 1.