JPS6125723A - Method and device for controlling electric discharge processing power supply - Google Patents

Abstract

PURPOSE:To enable the optional alteration of the peak value and rise ratio per unit time of the amplitude of electric discharge current pulse, by performing binary addition to an electrical current at the least significant bit of a counter to set other electrical currents at the more significant bits thereof. CONSTITUTION:When electric discharge is caused, the output of the electrical current pulse width setting unit 5 of a control means for the processing power supply of an electric discharge processing quipment takes a level H, a train of pulses is sent out from a NAND element 4, a counter 8 starts counting, outputs corresponding to a number of pulses are sent out from output terminals A0-D0, and an electrical current is stepwise increased as an inter-electrode current wave form. When the output of the counter 8 which corresponds to the current in the gap between electrodes has reached a value set by a current peak value setting unit 12, a condition for the element 4 is blocked to stop the passage of the train of pulses. The peak value and rise ratio per unit time of the amplitude of electric discharge current pulse can thus be optionally altered.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for controlling a machining power source of an electric discharge machining device that machines a workpiece by generating intermittent electric discharge in the gap between a machining electrode and a workpiece, and It is related to the device.

[Prior art]

Conventionally, as a power source for this heel electrical discharge machining device.

This device, which was disclosed in Japanese Patent Publication No. 44-13195, applies an electric current FE'& between the machining electrode and the workpiece to cause a discharge, and after the discharge occurs, a current is passed for a predetermined period of time. This is a device that then shuts down for a predetermined period of time.

According to this apparatus, it is known that processing can be performed with less electrode wear if the current pulse and current peak values are set at an appropriate level. However, with this device.

Processing copper with iron-based electrodes? If we use the workpiece as an example and the electrode is at a positive potential, the electrode weight consumption rate can be reduced to about 1 to 5%, but a consumption rate lower than that will require a significant increase in the current pulse width. Q] Under these conditions, the discharge frequency could not be increased, so there were disadvantages such as an extremely low machining speed.

Another example is the one shown in Japanese Patent Publication No. 47-2840-g, in which it is known that the electrode weight consumption rate can be reduced to less than 0.1 inch or less. A method of reducing electrode wear by making the rising and falling edges of the trailing edge steeper and increasing the current amplitude during the pulse duration,
(a) Setting the initial value of the pulse current oscillation value This step 5 is used to adjust the rate of increase per unit time of the current oscillation value. (o
The inductance and resistance shall be variable. (c)
A capacitor and a first gate are connected in series in parallel with the discharge gap, and a connection point between this series circuit and a parallel circuit of an inductance and a resistance is connected to the first gate workpiece 6(-1:l in parallel with the first gate). The rectifier is constructed by connecting a one-way conductive element in antiparallel to a single-power control rectifier.

In general, the former 01 device is often used, including its modifications and improvements, but the latter device is hardly used. In addition, even for sharpening tools that require low electrode consumption processing, the former device is usually used to obtain a neutral ζ strainer that increases the processing speed. The reason why the latter device is not used is because the circuit is a capacitor.

It is complex, including inductance and resistance, and changing the processing conditions requires changing the capacitor, inductance, and resistance, making it difficult to select values suitable for the application and processing details. , the peak current becomes too high and low surface roughness level 1 is not suitable.

[Summary of the invention]

This invention has been made to eliminate the drawbacks of the conventional CDO described above, and has a counter and a switching element corresponding to the binary output terminal of the counter, 0) Rise rate per unit time of the midpoint value of the discharge current pulse waveform, which is calculated by adding io×2n to the current value lo of the least significant bit and adding each current in binary as the upper bits move up. set the peak value arbitrarily,
Furthermore, the present invention provides a machining power supply control method and apparatus for an electrical discharge machining apparatus that can be easily changed.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained.

In FIG. 1, (1) is a clock signal generator, (2)
is a binary 1) rate multiplier (e.g. SN 7
497) and (6) are slope rate setters, which are input to the binary rate multiplier (2).

[41 is a NAND element, (5) is a current pulse width setter, (6) is a voltage pulse width setter, (C is a one-shot
The multivibrator, (8) is a counter, and (9) C is an initial current setting device, which inputs a binary signal to the counter (8).

(10) In the power element drive circuit, the counter (8
) is a circuit that transmits the signal corresponding to each binary output to the power element and performs switching.
5P), (12) is a current peak value setter.

FIG. 2 is a block diagram illustrating the current pulse width setting device (51 and voltage), the pulse width setting device (6), and (13) i
The workpiece, (14) is the machining electrode, (15) is the resistor for detecting the gap between the electrodes Ff and Y and dividing the voltage, and (16) is the comparator, which is the base voltage, the gap between the electrodes 3f, and the partial pressure value of E. Compare with. (17) Hawanshot multivibrator, (18) ijNOT element, (19111 current pulse width und circuit).

It consists of a device that sets the pulse width Y of the discharge current, a counter, etc.

Figure 6 shows a power switching circuit with resistors R1 to B@
, switching elements TR4 to TR, (transistors), (21) is a DC voltage source, (io) is a blower element drive circuit, (13) is a workpiece, (
14) is a machining electrode, and the resistances 11,1 to T(,) are determined to be a machining electrode whose value is R, -=Ri/2'' (y+=1 to 8).

Next, while referring to the timing chart (7) in FIG. 4, we will discuss the operation. First, in Fig. 2, when the output of the O-pulse setter (6) is at H level, that is, when the voltage E' is being applied between the electrodes, if a discharge occurs at this time, 't71FE' of the gap between the electrodes will change. , decreases, is detected by the comparator (16), and an elipulse output from the one-shot multivibrator (17) is generated. The [7 current pulse 1] setting device (5) receives the timing of the occurrence of electric discharge from the NOT element (18) and operates the current pulse width counting circuit (19) 'l' to obtain a predetermined current Halus width. After counting, it is output to the current pulse oscillator (5) and at the same time, it is output to the electrical pulse oscillator (6) to set the output of the fixed setting device to YL level, thereby stopping the voltage application to the gap between the poles. The pause pulse width count circuit (20) is
Starts operation by the signal from the voltage pulse setting device (6),
After counting the predetermined rest time, 'kx8: Pulse width setting device (
6), and no voltage is applied to the gap between the electrodes again. In FIG. 1, the voltage pulse width setting device (61
When the output of the counter (8) reaches L level, the output terminal A of the counter (8)
. + Bo + (-o All +D0 become L level, and the power element drive circuit (10) becomes the power element TR.
, 1 to TR, all 8 are turned OFF'. On the other hand, when the output of the voltage pulse width setting device (6) becomes H level, the counter (8) becomes possible to input the pulse input terminal (CD),
In addition, the load terminal (LO) receives the pulse signal of the one-shift multi-pipe brake C71, c, reads the output of the initial current value setter (9), and outputs the output terminals A6, B6,
C(1, output to Do. For example, initial current value setter (
9) Data is DA, DBb″-H level, DC, D
When D is at L level, power elements TR,..., TR・2
are turned on, and 5TP3 to TR8 are turned off, thereby connecting the resistors R, l, R, , between the poles. Also, binary
The output of the rate multiplier (2) becomes a pulse train with a frequency set to 1 in the slope rate setter (81), and is output to the NAND element (41), but the output of the current pulse setter (51) is output to the NAND element (41). When it is at L level, the NAND condition is not satisfied and no pulse train is output to the counter (8).

When discharge occurs, the output of the current pulse width setting device (5) becomes H level, a pulse train is output to the NAD element (4), the counter (8) starts counting, and the output terminal AO# is output according to the number of pulses. BO@C0e D(lEri output level 1) The current increases in a stepwise manner according to the current waveform between the poles shown in Figure 4.On the other hand, the output terminal of the counter (81) is connected to the digital comparator (11 It has been done.

The digital comparator (11) compares the output of the current peak value setter (12'y/) and sets the output terminal YH level while the output of the counter (8) is small;
) becomes equal or becomes larger, it is set to L level and output to the NAND element (4), that is, the output of the counter (8) corresponding to the current in the gap between the electrodes is set at the current peak value setting device (12). When the set value is reached, the NAND element (blocks the condition 41) stops the pulse train from passing.

Figure 5 shows the wFE waveform fal and the current waveform fblIc between the poles.
Tweet, Telephone [Pulse width setting device (6) output tel (
! : This shows the correspondence with the 1M current pulse width setter (5) output [dl. In the above example, a pulse train equivalent to a current step was generated using a binary rate multiplier, but a variable frequency transmitter? May be used. Also, current peak value setting? Although this was done using a Digimel comparator, it can also be configured using a counter, etc. Further initial current setting? Although the counter is initially set, a power element drive circuit and a power element that directly respond to the output of the Gunou pulse width setter may be provided. Furthermore,
In the above embodiment, the switching circuit is configured using a constant voltage source and a current control resistor, but even if the switching circuit is configured using a constant current source, the present invention has the same effect as the above embodiment. , a counter and a switching element corresponding to each output of the counter? and the current value of the least significant bit of the counter is 10, and the current value of the upper bit is 16×2n.
Since the counter is configured so that the counting operation of the counter starts from the moment when the discharge occurs, the rate of increase per unit time of the amplitude value of the current pulse waveform and the low leakage value can be arbitrarily and easily changed. can also be wealth,
It is possible to maintain a constant flow peak value and prevent deterioration of surface roughness.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of a machining power source tilting device according to an embodiment of the present invention, FIG. 2 is a partial circuit diagram of a pulse oscillator of the machining power source, and FIG. 3 is a power circuit diagram of the present invention. Figure 4 is a timing chart, and Figure 5 is a waveform diagram showing interpolation \tIE waveform and current waveform. (1) Clock signal generator, ]2) Binary rate multiplier , (3)... Slope rate setting device, (4)... NANJ) SC-7% (51...
Current pulse setting device, (6)... Voltage pulse setting device, +7...One-shot multivibrator, (8
)...Counter, (9)...Initial current value setter. (10)...Power element drive circuit, (11)...
・Digital comparator, (12)...Current peak value setting 5-(13)...Workpiece, (14)...Both machining poles, (15)...Resistance, (16)...Comparator, (17)... One-shot multivibrator, (18)... NOT element, (19)... Current pulse width counting circuit + (20)... Rest pulse width counting circuit, (21)...・DC voltage source, in Fig. 5, fal...Tsubaki market pressure waveform, (bl...Central current waveform, (cl...Voltage pulse width setting device output, Td
l... Output of current pulse width setting device. Note that the same reference numerals in the drawings indicate the same or corresponding parts. Agent Patent Attorney Sanro Kimura 111 Figure L j Figure 2 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) In an electric discharge machining device that processes the workpiece by applying a voltage to the gap between the machining electrode and the workpiece to generate intermittent discharge, the initial value of the current flowing through the gap is determined, and the electric discharge machining A current having the initial value is passed when starting the process, and the current value is sequentially increased stepwise at a predetermined period, and when the current value reaches a predetermined peak value, the increase in the current value is stopped. A power supply control method for machining of an electrical discharge machining device. (2) A binary counter and a plurality of pairs of switching circuits each having a switching element and a current limiting resistor connected in series are provided, and each of the switching circuits responds to the binary output terminal of the binary counter, and each of the switching circuits responds to the binary output terminal of the binary counter. A machining power supply control device for an electric discharge machining apparatus, characterized in that the current value is set to an initial current value i_0×2^n corresponding to the bit of the binary output, and the binary counter is driven by a pulse train from the time of occurrence of electric discharge. .