JPS61274815A - Electric discharge machining control device - Google Patents

Abstract

PURPOSE:To improve machining performance, by providing a main spindle feed gain controller so as to perform a servo control of good follow-up property, in the case of a control device having a discriminator circuit, adjusting a machining gap corresponding to every pulse or plural pulses, and a position control servo system. CONSTITUTION:An up-signal and a down-signal, which are obtained from a discriminator circuit 18 adjusting a machining gap corresponding to every pulse or plural pulses, are supplied to AND circuits 22, 24, and a control device obtains an AND output from an output side to be integrated for a required time in an updown counter 26. The device holds this counted value in every predetermined time in a register 28 to be output to a main spindle feed gain controller 52. And the control device, outputting to a sample value control system a servo signal, which controls a main spindle feed gain so as to be decreased when a difference between the present output value of the register 28 and its just preceding output value is larger than a preset value while so as to be in the preset value when the difference is smaller than the preset value, to be converted into a main spindle position command value, performs a high accurate gap control.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an electric discharge machining control device, in which a special electrode and a workpiece are opposed to each other through a machining gap, and the machining gap has sampling, calculation, and hold functions. This relates to an electrical discharge machining control device controlled by a position control servo system having There is. In this first step, a hydraulic cylinder, a pulse motor, a servo actuator using an Ii flow motor, etc. is used as the electrode drive device, and a position with sampling, logical operation, and hold functions is used to control the machining gap. Attempts have been made to apply a control servo system, and this position control servo system uses a general-purpose processing device such as a microprocessor, a Lisa, or a minicomputer.

As this type of electrical discharge machining control device, one shown in FIG. 8 has been proposed.

That is, the machining gap α→ between the machining electrode αG and the workpiece @
is formed, and electrical discharge machining is performed by applying a current-controlled r co-pulse voltage from a power source αG to this machining gap α4.

(to) is a determination circuit that measures the discharge start time after applying a pulse voltage to the machining gap α4 until the discharge starts, and determines whether this is the first time that is shorter than the predetermined first time.
, a second time region that is longer than the first predetermined time and shorter than the second predetermined time, and an eighth time region that is longer than the second predetermined time or in which no discharge occurs during the application time of the pulse voltage. The servo signal shown in FIG. 2 A and B in this servo signal outputs a servo signal in the direction of narrowing or widening the machining gap α based on whether Only the up signal 8U and down signal 8D are supplied to the AND circuits to which the clock pulses were supplied, and these AND circuits The logical product outputs shown in FIG. 2 C and D are obtained from , respectively, and these are supplied to up/down counters (E) to perform integration over a predetermined time. Regardless of the voltage pulse width, the a.・・Bu signal 8U and down signal SD
Calculation 9 (E) is used to determine the ratio of RESET_I to the logic operation circuit (C) which will be described later.
will be played. Therefore, the counter counter sequentially counts pulses A and I from time 1+, as shown in FIG.
The final count value is held for t3 and is sequentially subtracted by counting down pulses from time t3, and Δ
It is reset at time t4 when T time has elapsed, and the above operation is repeated 2 times.
Repeat every hour.

The count output of the counter (7) is supplied to the register @ζ, and the output from the arithmetic circuit (c) is applied to this register by the save signal S8 shown in the second diagram, which is obtained just before the save signal SR. The stored integral signal of the servo signal in register 9 is converted into a spindle position command value according to the voltage between the poles by a device (to) that has the functions of sampling, logical operation, and holding. , The device (7) is supplied with an input terminal (to) that receives the output of the register (to), the output of this... It is composed of a logical operation circuit (c) which outputs the reset I signal SR and the set/set signal SS, and an output circuit (to) which holds the output value of this circuit (c). Logic operation circuit (goods) is error callan 9C! The following error 2ε between the output of B, that is, the zero-order hold output Zc of the latch (to) and the spindle position detection signal Zf is read, and this is added to the spindle position command value, and the resulting command value is output. lchi(
until the next command value is output.

The command "-" held in the output arm is supplied to the error counter (to) that constitutes the position servo system, and the command value from this counter is detected by the spindle position detector (to). It is subtracted by the signal Zf representing the spindle movement amount, and a γ position error signal 2ε is output.

The position error signal 2ε of the error counter (to) is converted into an analog signal by the D/A converter (a), and the electrode consisting of the speed amplifier (6), the DC servo motor, and the finger speed generator) is supplied as a speed command to the drive speed control servo system of The machining gap α→ is maintained at an appropriate value by moving the DC servo morph until it becomes the same.

[Problem that the invention seeks to solve]

According to the above-mentioned conventional device, the circuit determines the time until the discharge starts after applying the machining gap α pulse voltage.
The machining gap α4 can be maintained at an appropriate value by detecting it in the sample value control system. In the method, the spindle feed gain G is
=8i (K is a constant), but due to the limitation that the mechanical system response time is slow compared to the gap state change time, follow-up control may not be possible and an oscillation state may occur, especially in the finishing area. In many cases, machining performance has to deteriorate.

The present invention was made in view of the above-mentioned problems in the prior art, and its purpose is to perform servo control with good followability by controlling the spindle feed gain as a function of the differential value of the interpole servo main signal. [The first means to solve the problem] The aim of the present invention is to provide an electrical discharge machining control device that can maintain the machining gap state in a stable machining region at all times and improve machining efficiency. The electrode and the workpiece with zero wave force are opposed to each other with a machining gap interposed therebetween, and $11@ is placed in the machining gap.
a discrimination circuit that applies a pulse voltage applied to the γζ, measures the discharge start time required until the γζ post-discharge occurs, and outputs a servo signal for adjusting the machining gap; In an electrical discharge machining control device having a position control servo system that servo-controls the servo system, the servo signal of the discrimination circuit is supplied to an up-down counter that integrates at a predetermined period corresponding to the sampling period, and the count value of the up-down counter is calculated. It is supplied to the register 9 which is held at every predetermined cycle, and when the difference between the output values of the register at every predetermined cycle is greater than or equal to the set value, the spindle feed gain is set to 7! The dynasty feed gain is controlled as a function of the difference in the output values of the registers so that the difference in the output values of the registers decreases, and the dynasty feed gain is controlled to a predetermined dynasty feed gain when the gain is equal to or greater than the set value. The output is supplied to the position control servo system.

[Effect]

In this invention, the dynasty feed gain is controlled as a function of the differential value of the servo signal between poles. are given the same reference numerals and a detailed explanation thereof will be omitted, but according to the present invention, in the 80th configuration, the dynasty feed gain system a bag direct Q between the register (7) and the input column of the device (to) This dynasty feed gain control device 521, which has a configuration in which the dynasty feed gain control device 521 has a configuration in which a
If the difference in the output signals from If the spindle feed gain is small, the spindle feed gain is controlled to a predetermined value. The up/down signal 8U and down signal 8D shown in A and Bl are obtained, and these are supplied to the AND circuits - and Kan, and the AND outputs shown in Fig. 2 C and D are obtained from their output sides. , this is integrated over a predetermined time by an up/down counter (7). The count value of the counter every predetermined time is held in the register and output to the dynasty feed gain control device 6z.

Thereafter, the same operation is repeated, and if the difference between the current output value of the register and the output value immediately before it is larger than the set value from the dynasty feed gain control device, the register outputs the dynasty feed gain so that the dynasty feed gain decreases. A servo signal is output to the sample value control system to control the dynasty feed gain as a function of the difference in values, and to control the spindle feed gain to a predetermined value when the difference in the register threat output values is smaller than a set value.

This servo signal is first processed by a device (1) having sampling, logical operation, and hold functions to generate a voltage between poles ζζ.
It is converted into the corresponding spindle position command value. Here, the logic operation circuit (c) reads the output of the error counter (to), that is, the difference (following error) 2ε between the zero-order hold output zO and the position detection signal Zf, adds it to the spindle command value, and calculates the difference in the fifth-order minute time. Calculate the zero-order hold output. By this operation, even in the zero-order hold control of the position servo system, it is possible to safely close and close the position, and high-precision gap control is possible.2 The zero-order hold output described above is This error counter (to) is sent as parallel data.
Since the output of the error counter (to) becomes an impulse output during presetting, sufficient starting torque can be generated for the DC servo motor, and a servo system with good responsiveness can be constructed. It goes without saying that the magnitude of the impulse signal is set to a value that does not overshoot, taking into account the characteristics of the intuitive servo motor, the load characteristics, the predetermined minute time, etc.

〔Effect of the invention〕

As described above, according to the main F4yAf, the servo signal from the discriminating circuit for discriminating the state of the machining gap is supplied to the A and J down counters that integrate at a predetermined period corresponding to the sampling period. A spindle feed gain control device that controls the spindle feed gain for each predetermined period is added to the digital integration circuit that holds the count value for each cycle, and a servo signal during the sampling interval is combined with the sample value control system. It is possible to stably sample the servo signal over the entire time domain without being ignored, and the output of the zero-order hold circuit that outputs the position control command to the position servo system is reset, and the electrode position signal and An error counter that outputs the difference between
A D/A converter is provided that outputs the count output to the speed servo system.1 This makes it possible to achieve a completely closed loop position even in zero-order hold control, making it possible to control electrical discharge machining using a sample value control system. However, it is possible to accurately detect the machining gap condition, and based on the detection results, it is possible to perform servo control with extremely good followability in response to the machining gap condition, improving machining performance. You can measure your improvement.

[Brief explanation of drawings]

Fig. 1 is a flow diagram of an electric discharge machining control device according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of the conventional electric discharge machining control device and the present invention, and Fig. 8 is a conventional IC271 control device. In the figure, αG is the processing electrode, (2
) is the workpiece, α4 is the discharge gap, (to) is the discrimination circuit, (
c) is a logical operation circuit, (to) is a -7 down counter, (to) is an error counter, (to) is a D/A converter, (
Product) is a DC servomorph. In the figures, the same symbols indicate the same or equivalent parts.

Claims (1)

[Claims] After the electrode and the workpiece are opposed to each other through a machining gap and a controlled pulse voltage is applied to the machining gap, a servo signal is output to adjust the machining gap for each pulse or in response to multiple pulses. In the electric discharge machining control device, the servo signal of the discrimination circuit is controlled at a predetermined period corresponding to the sampling period. The count value of the up-down counter is supplied to an up-down counter for integration, and the count value of the up-down counter is supplied to a register that holds it every predetermined period. An electric discharge machining control device characterized in that the gain is changed and controlled so that the gain is changed and controlled, and the gain is supplied to a spindle feed gain control device, and the output of the spindle feed gain control device is supplied to the position control servo system.