JPS5856735A - Discharge work controller - Google Patents

Abstract

PURPOSE:To achieve stable sampling of a servo signal in the entire time region, by feeding back up and down signals for each charging voltage in the integrated stage through an up/down counter and a register, to the servo system. CONSTITUTION:Up and down signals from a decision circuit 18 corresponding to each charging voltage and a referential clock 46 of the pulse width narrower than said charging voltage width are integrated for the predetermined time by a cuonter 52 through AND gates 48, 50. On the other hand set 58 and reset 56 signals are produced from a logic operating circuit 24 for every sampling interval DELTAT to set the count from the counter 52 in a register 54 then reset the counter 52 to upcount from the count (a) and to hold said count between (b) and (c) then to down count while after elapsing the interval DELTAT the count (d) is set in the register 54 by an output signal from the citcuit 24. Similar operations are followed to feed a servo signal during the sampling operatin to the servo system under the integrated state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machining control device, which controls a machining gap between a 0VC pole and a workpiece by a position control servo system having sampling, calculation, and hold functions. It is.

In general, the servo system of the W7J construction requires rapid control of the machining gap according to the discharge state.

For this reason, a servo actuator such as a hydraulic cylinder, a pulse motor, or a DC servo motor is used as the drive device for the W pole, and a position control servo system with sampling, logical calculation, and hold functions is used to control the machining gap. Attempts have been made to use it. This position control servo system uses, for example, a processing device such as a microprocessor or a mini combinator.

FIG. 1 shows an example of a conventional electric discharge machining control device of this type, in which a DC servo motor is used as the actuator. In Figure 1, [#M@
In the machining gap where and workpiece α→ are opposed, 1fWIJ
A charging voltage of 11 is applied from I to the capacitor (1), and this charging voltage is determined by a discrimination circuit (to) for each discharge time region, and a servo signal (gran) in the direction of narrowing the machining gap or a servo signal in the direction of widening it. After being converted into a signal (up), it is sent to device 4, which has sampling, logical operation, and hold functions.

In the above device, the input car latch circuit 4 samples the servo signal at regular intervals JT.

This sampled servo signal is converted by the logical operation circuit (c) into a spindle position command value according to the servo signal, and this command value is held by the output latch (2) until the next command value is output. be done.

This command value is a binary rate multiplier (BR
The parallel digital output is converted into a serial digital output by M) and is given as a count input to an error counter (to) constituting the position control servo system. This counter (1) subtracts the above command value by the spindle diameter 6ttJt detected by the spindle position detector (incorporated), and the position error value, which is this subtracted value, is This converted signal is converted into a signal, and this converted signal is sent to the speed amplifier 6K, DC servo motor (to)
The driving speed of the above-mentioned ipole is given as a speed command to the power supply system, which is composed of the finger speed power generation system and the finger speed power generation system. This
``From LK, move the DC servo motor e to rotate the ball screw (g), move the main shaft □□□ to which the electric j There is a method that controls the machining gap by rotating a DC servo motor until it becomes equal.

Next, the operation of the above-mentioned discrimination circuit (to) will be explained. The voltage and current waveforms appearing in the machining gap in FIG. 1 are normally as shown in FIG. 2, where (a) is the voltage waveform, and (b) is the current waveform.

In the same figure (a), the charging voltage changes depending on the state of the machining gap, and in a normal machining gap, discharge occurs when the charging voltage reaches the applied voltage value (100), and the arc potential (101 ) At this time, a current (104) shown in the figure (b) flows, and the discharge ends. Further, when the machining gap is wide, the no-load time (105) increases, leading to a decrease in machining efficiency. On the other hand, when the machining gap is narrow, insulation recovery in the machining gap is not appropriate, so discharge occurs before the charging pressure reaches the applied voltage, and only an extremely small amount of energy can be supplied, resulting in a decrease in machining efficiency.

Normally, the appearance of the no-load voltage (105) as described above means that the dielectric strength in the machining gap has sufficiently recovered, so in order to generate a "down signal" as a servo signal, the voltage is detected A level (102) is provided, and if the voltage between electrodes is higher than this, Wt2 diagram (d)
When the inter-electrode voltage is below the voltage detection level (103), the "lowering signal" shown in Fig. 2 (c) is generated.
Generate a "raise signal".

Further, when the detection level is between A/(10B) and (102), the servo is in the "stop area". As described above, the discrimination circuit (to) outputs a servo signal for each charging voltage.

As described above, the conventional discrimination circuit (to) outputs a servo signal in response to the charge voltage - one shot, so the sample is used as an input to the sample A/value control system that samples every fixed l1 interval. Since the instantaneous value of time M is sampled and the servo signal during the sampling interval is ignored, it is clear from the sampling theorem that
It was difficult to form a fill of about 1/2 of the number, and as a result, it was difficult to perform servo control with good followability.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide an electric discharge machining control device that can perform servo control with good followability.

In order to achieve the above object, the present invention connects a capacitor in parallel to the machining gap with the workpiece facing each other, and based on the light N''k pressure to the capacitor, the machining gap is a first time region determined according to a voltage range lower than the first voltage detection level, and a voltage detection level higher than the voltage detection level in 6.q 1 above;
A second time region determined by a voltage range lower than the voltage detection level of 8g2 and an eighth time region determined by a voltage range higher than the second voltage detection level. In an electric discharge machining control device comprising a discrimination circuit that outputs a servo signal and a sample value control position servo system that servo-controls the machining gap based on the servo signal of the discrimination circuit, the discrimination circuit corresponds to each of the pulse voltages. An up-down counter that integrates the servo signal at a predetermined period corresponding to the sampling period, and a register that holds the count value of this up-down counter for each predetermined period are provided, and the output of this register is used in the position control servo system. It is characterized by adding to.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 8 shows a clock diagram of the present invention in which the same parts as in FIG. AND circuit - and connected to the ring. The output terminals of this AND circuit ■ and - are connected to the up input terminal and down input terminal of the up/down counter wheel, and the output side of the up/down counter wheel has a register that holds the count value of the up/down counter. The output of this register is connected to the input circuit inside the device. The reset terminal R1 of the up-down counter and the set terminal SK of the register are connected to a logic operation circuit (c).

The embodiment of the present invention has the above configuration.
The operation will be explained with reference to the operation explanatory diagram shown in the figure. In Fig. 4, (a) and (to) are up and down servo signals output from the discrimination circuit (to), (Q)
and) are the input signals supplied to the up input terminal and down input terminal of the up/down counter Q, (e) a
Set signal supplied to terminal S, () of the register, (
f) is a reset signal supplied to the reset terminal R of the up-down counter, and (b) shows the counting state of the up-down counter wheel.

First, see Figure 4 for each charging voltage).

As shown in (b), only the up signal and down signal are extracted from the servo signal from the discrimination circuit. In order to find the ratio of the up signal and down signal within a predetermined time regardless of the charging voltage width, the output of a high frequency reference clock circuit with a pulse width extremely narrower than the charging voltage width and the above up signal and down signal are compared. AND circuit −, 11+1
W7t4 diagram (C), ←
) is sent to the up/down counter for integration over a predetermined period of time.

-4. As shown in Figure 4 (e) and (f) every 11 hours corresponding to the sampling period, when the set signal (■) and the reset signal (to) are outputted to the logical operation circuit (c), the above-mentioned reset occurs. Depending on the signal, the above up/down counter (
The count value of b) is set in the register. Next, after being reset by the above reset signal, the up/down counter f4 counts up pulses from member (2) in FIG. 4, holds the count value at (2), and counts down pulses from (2) After the time T, the count value of 2 is set in the register by the set signal output from the logical operation circuit. Thereafter, by performing similar operations, the servo signal can be sent to the sample value control system via the register in the form of an integrated servo signal during the sampling interval.

As described above, the present invention includes an up-down counter that integrates a servo signal from a discriminating circuit that determines the shape of a machining gap at a predetermined period corresponding to the sampling period, and a count 1 of this up-down counter for each predetermined period.
Since a digital integration circuit having a register etc. that holds 11f is combined with the sample value control system, it is possible to stably sample the servo signal over the entire time domain without ignoring the servo signal during the sampling interval, and the sample value It is famous for being able to accurately detect all machining gap conditions even in electrical discharge machines, which are control systems.
Based on the detection results, servo control with extremely good followability corresponding to the machining gap state can be performed, which has the effect of improving machining performance.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional frame processing system. I! 2 is an illustration of the above-mentioned apparatus, FIG. 8 is a block diagram of the electrical discharge machining control apparatus of the present invention, and FIG. 4 is an illustration of the operation of the apparatus of the present invention. In the figure, the expression is the actuator, (to) is the ', and α is the actuator.
→ is the workpiece, Qfe & [ source, (to) is the discrimination circuit, @ is the input car latch circuit, % is the logic operation circuit, @ is the output latch,
(to) is the binary rate map chip 1 year, ... is the error Curran IJ% (Foundation) is the digital M/analog converter,
CI4 is the speed amplifier, (to) is the DC servo motor, (to) is the finger speed generator, (to) is the ball screw, (2) is the main shaft,
@4 is the main axis position fl detector, 2) is the reference clock circuit, -
The 9 wheels are an AND circuit, the 1 wheel is an up/down counter, and @ is a register. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Shin Kuzuno −

Claims (1)

[Claims] A capacitor is connected in parallel in a machining gap where an electrode and a workpiece face each other, and the elapsed time until the machining amount NK discharge occurs is calculated based on the charging voltage to the capacitor. a first time range determined by a voltage range lower than the voltage detection level V;
a second time domain determined by a voltage range higher than the detected voltage level V and lower than the second voltage detection level;
The processing gap is divided into iEg time domains determined by the voltage range higher than the second voltage detection V, and the processing gap is narrowed based on the time domain detection signal of each charging voltage that is sequentially applied to the processing gap. A discrimination circuit that outputs a servo signal in the direction or direction of expansion, and a sample value control position ml? that servo-controls the machining interval @ based on the servo signal of this discrimination circuit. - The discharge W machine control device i1 equipped with a control system includes an up-down counter that integrates the servo signal of the discrimination circuit corresponding to the charging voltage at a predetermined period corresponding to the sampling period, and a predetermined period of the up-down counter. An electric discharge machining control device characterized in that a register is provided to hold a count tMf of each time, and the output of this register is applied to the sample value control position servo system.