JPH0463625A - Discharge machining device - Google Patents

Abstract

PURPOSE:To utilize all discharge characteristic values for statistics processing by reading out the count value from an auxiliary memory during the period synchronized with the timing pulse generating period, and reading out the discharge characteristic value data for the count value from a first-in first-out type memory. CONSTITUTION:When an electric discharge is started, a measurement section 1 measures and outputs the discharge characteristic value as the discharge characteristic value data AD and outputs a writing command Wa when the discharge is completed, a first-in first-out type memory 2 receives and stores the discharge characteristic value data AD, a counter 3 counts the writing commands Wa to count the number of discharges, and the discharge characteristic value data AD of individual discharges are written into the first-in first-out type memory 2 in sequence. The counter 3 counts the number of discharges generated during the preset period T, and an auxiliary memory 4 stores the number of discharges during the previous period T. A controller 6 reads out the number of discharges from the auxiliary memory 4 during the same period synchronized with the pulse generating period T and reads out the discharge characteristic value data AD of discharges generated during the previous period T from the first-in first-out type memory 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a die-sinking electrical discharge machining apparatus. In particular, the present invention relates to an electrical discharge machining apparatus that detects a machining state of electrical discharge machining and controls electrical discharge machining according to the detected machining state.

Conventional electrical discharge machining equipment detects the electrical discharge machining state and controls the gap between electrodes, voltage application time, rest time, etc. according to the machining state to optimize electrical discharge machining. .

In order to detect this electrical discharge machining state, various electrical discharge characteristic values are measured. Important characteristic values that indicate the electrical discharge machining state include the discharge delay time from when a voltage is applied between the electrodes until the insulation is broken and the discharge current flows, and the peak value of the voltage between the electrodes. Further, discharge characteristic values include peak current, leakage current, etc.

For example, when the distance between the electrodes increases, the discharge becomes unstable and the discharge delay time increases. Furthermore, if the distance between the electrodes is too short or the machining fluid is contaminated, insulation recovery after discharge will be insufficient, resulting in a state close to a continuous arc. When this phenomenon occurs, the peak voltage decreases. In this way, the machining state can be detected based on discharge characteristic values such as discharge delay time and peak voltage between electrodes.

These discharge characteristic values are measured, and the control unit controls the discharge machining to be optimal based on the measured discharge characteristic values.However, in conventional electric discharge machining equipment, the measured discharge characteristic values are used for the next The discharge characteristic value is held until discharge, and the control unit uses only the discharge characteristic value held immediately before performing calculation processing for control, performs calculation processing, and controls the electrical discharge machining apparatus. That is, the discharge characteristic values are sampled every cycle of calculation processing, and the calculation processing for control is performed using this sampling data, and the discharge characteristic values of all discharges are not used.

Furthermore, a method has also been adopted in which the average of discharge characteristic values is determined by analog calculation and the electric discharge machining apparatus is controlled based on the average value.

Problems to be Solved by the Invention Discharge characteristic values such as the discharge delay time and the peak value of the voltage between the electrodes are important in understanding the electrical discharge machining state as described above, but they vary widely for each discharge, and due to sampling It is difficult to accurately grasp the machining state based on individual discharge characteristic values. It is desirable to collect as many discharge characteristic values of each discharge as possible and to perform statistical processing based on these data to understand the machining state.

Therefore, in conventional devices, a method has been adopted in which the frequency of sampling the discharge characteristic values, that is, the processing cycle for control, is shortened to increase the frequency of use of the discharge characteristic values of each discharge. is much shorter than the arithmetic processing cycle of the control device, making it impossible to obtain sufficient sampling data.

In addition, the method of calculating the average value of the discharge characteristic values by analog calculation can only use part of the information possessed by each discharge characteristic value, which is insufficient to understand the machining state.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electric discharge machining apparatus in which discharge characteristic values of all electric discharges can be used for statistical processing for electric discharge control.

Means for Solving the Problems The present invention provides an electric discharge machining control device that controls electric discharge machining based on electric discharge characteristic values measured by a measuring means that measures electric discharge characteristic values for each electric discharge during electric discharge machining. A first-in, first-out type memory that sequentially stores discharge characteristic value data of each discharge measured by the means, a counter that counts the number of discharges, an auxiliary memory that stores the counted value of the counter, and a timing pulse that generates a timing pulse every predetermined period. By providing a timing pulse generator that stores the counted value of the counter in the auxiliary memory and clears the counter, the control section of the electrical discharge machining apparatus can operate at a cycle synchronized with the timing pulse generation cycle of the timing pulse generator. , the count values stored in the auxiliary memory are read out, and each discharge characteristic value data is read out from the first-in, first-out type memory as many as the read count values, and the discharge characteristic values of all discharges are used for statistical processing for discharge control. I made it possible.

The discharge characteristic values of each discharge measured by the action measuring means are sequentially stored in the first-in, first-out memory. Further, the counter counts up and counts the number of discharges every time the discharge characteristic value of the discharge is detected, that is, every time a discharge is performed. On the other hand, the timing pulse generator generates a pulse every predetermined period, inputs and stores the count value of the counter in the auxiliary memory, and then clears the counter.

Further, the control device of the electrical discharge machining apparatus reads the number of electrical discharges stored in the auxiliary memory in the same cycle in synchronization with the pulse generation cycle of the timing pulse generator, and reads out the number of electrical discharges stored in the auxiliary memory in synchronization with the pulse generation cycle of the timing pulse generator, and stores the electrical discharges of each electrical discharge from the first-in, first-out memory. Characteristic values are read and various statistical processing for discharge control is performed.

Example FIG. 1 is a block diagram of one embodiment of the present invention.

1 is a measurement unit that measures the discharge characteristic value of each discharge, and it starts counting when the switching element etc. is turned on and voltage is applied between the electrodes, and when the discharge starts and the voltage between the electrodes suddenly increases. A timer that measures the discharge delay time during the drop,
It is comprised of conventionally known discharge characteristic value measuring means such as a voltage detector having a peak hold circuit and detecting the peak voltage between the electrodes. Furthermore, the measurement unit 1 includes an A/D converter that converts each discharge characteristic value measured by each discharge characteristic value measuring means into a digital signal, and each discharge characteristic value data AD converted into a digital signal is First-in, first-out memory 2
The discharge characteristic value data AD is written into the first-in, first-out memory 2 according to the write command Wa sent from the measuring section 1 when the discharge of a predetermined time width is completed and the switching element is turned off. The first-in, first-out memory 2 is a dual-port memory or the like having a configuration in which writing and reading can be performed independently, and data that is input first is read out first. In addition, in the electric discharge machining in this example, a voltage is applied between the electrodes, electric discharge occurs,
A type of discharge in which the switching element is turned off after the discharge has been carried out for a predetermined time, and after a predetermined off time (discharge body stop time), the switching element is turned on again and a voltage is applied between the electrodes. It is processing.

3 is a counter that counts the number of discharges by counting the write command Wa output from the measuring section 1. Further, 4 is an auxiliary memory, and 5 is a timing pulse generator. The timing pulse generator 5 outputs a write command wb to the auxiliary memory 4 at predetermined intervals T, and stores the value of the counter 3 in the auxiliary memory 4. , and then outputs a clear signal C to the counter 3 to clear the counter 3. Reference numeral 6 denotes a control unit such as a numerical control device for controlling the electric discharge machining apparatus, which reads electric discharge characteristic value data and performs various statistical processing for electric discharge control to control electric discharge machining.

FIG. 2 is a timing chart in a process in which the control section 6 reads the electrical discharge machining characteristic value data AD, and the operation of this embodiment will be explained with reference to this timing chart.

When the discharge starts, the measurement unit 1 measures discharge characteristic values such as the discharge delay time and the peak voltage between electrodes, performs A/D conversion, and outputs the discharge characteristic value data AD, and when the discharge ends, When the switching element turns off, write command W
a (see FIG. 2(a)). Write command Wa
When is output, the first-in, first-out memory 2 takes in and stores the discharge characteristic value data AD. Further, the counter 3 counts the write command Wa (see FIG. 2(b)).
. Thereafter, the number of discharges is counted by counting the write command Wa with the counter 3, and the first-in first-out memory 2
The discharge characteristic value data AD of each discharge is sequentially written into.

On the other hand, the timing pulse generator 5 outputs the write command wb to the auxiliary memory 4 every predetermined period T, and then outputs the clear command C to the counter 3 with a slight delay (see FIG. 2(c)). When the write command wb is output, the auxiliary memory 4
takes in and stores the value of the counter 3, and when a clear command C is issued, the counter 3 is cleared and the count value becomes "0". That is, the counter 3 counts the number of discharges that occurred during one predetermined period, and the auxiliary memory stores the number of discharges that occurred during the previous period (see Figure 2 (d).
)reference).

On the other hand, the control unit 6 of the electrical discharge machining apparatus operates in synchronization with the pulse generation period T of the timing pulse generator 5 at the same period.
After the write command wb is output, a read command Rb is output to the auxiliary memory 4, and the number of discharges stored in the auxiliary memory 4 is read.

Then, a read command Ra is output to the first-in, first-out memory 2 for the number of read discharges, and each discharge characteristic value data AD of the discharges that occurred within the previous cycle T is read (see Fig. 2).
(see e)).

In this way, the discharge characteristic value data AD of the discharge that occurred during the period T of the previous cycle is read into the control unit 6 of the electric discharge machining apparatus, and based on the discharge characteristic value data AD, the average value, standard deviation, etc. Various statistical processes are performed to determine the state of electrical discharge machining, and electrical discharge machining is controlled by adjusting the gap between electrodes, voltage application time, rest time, etc. Note that this method is of various types and is already known, so a description thereof will be omitted.

In the above embodiment, the timing pulse generator 5 is provided, but the operation of the timing pulse generator may be performed by the control section 6 of the electrical discharge machining apparatus.

Effects of the Invention In the present invention, the discharge characteristic value data of all discharges during electric discharge machining can be detected and various statistical calculation processes can be performed based on this discharge characteristic value data, so that the electric discharge machining state can be improved. Since it can be detected accurately, it becomes possible to optimally control the electric discharge machining apparatus. Furthermore, if the controller of the electrical discharge machining device reads the discharge characteristic value data of each discharge from the first-in, first-out memory for the number of discharges read from the auxiliary memory, the temporal correlation of the data becomes clear, and batch reading from the memory is possible. , − data can be read out faster than in the case of reading out the discharge characteristic value data individually.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is an operation timing chart of the embodiment. 1... Measuring section, 2... First-in, first-out memory, 3.
... Counter, 4... Auxiliary memory, 5... Timing pulse generator, 6... Control unit of electrical discharge machining device.

Claims (1)

[Claims] In an electric discharge machining control device that controls electric discharge machining based on electric discharge characteristic values measured by a measuring means that measures electric discharge characteristic values for each electric discharge during electric discharge machining, electric discharge characteristic values of each electric discharge measured by the above-mentioned measuring means are used. A first-in, first-out type memory that sequentially stores data, a counter that counts the number of discharges, an auxiliary memory that stores the counted value of the counter, and a timing pulse that generates a timing pulse every predetermined period to store the counted value of the counter in the auxiliary memory. and a timing pulse generator that stores and clears the counter, and the control unit of the electrical discharge machining apparatus reads out the counted value stored in the auxiliary memory at a period synchronized with the timing pulse generation period of the timing pulse generator. An electric discharge machining apparatus characterized in that each electric discharge characteristic value data is read out from the first-in first-out memory as many times as the read-out number, and statistical processing for control can be performed.