JPS61279429A - Electric discharge machining controller - Google Patents

Abstract

PURPOSE:To provide servo control with satisfactory follow-up property by supplying the difference between the output values in every predetermined cycle of a register to a spindle feed gain controller for controllably changing the gain into zero in a predetermined set range to supply the output of the controller to a position servo system. CONSTITUTION:The servo signal of a judging circuit 18 permits an AND circuit to obtain the AND output which is integrated for a predetermined time in an UP-DOWN counter 26. The values counted by the counter 26 in every predetermined time are held in a register 28 to be generated to a spindle feed gain controller 52. Thereafter, similar operations are repeated. When the difference between the present output value and the right preceding one of the register 28 is larger than a set value, the spindle feed gain as a function of the output value difference of this register is controlled by said controller 52 to reduce the gain, and when said output value difference is smaller than the set value, the servo signal for controlling the spindle feed gain to a predetermined value is supplied to a sample value control system.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electric discharge machining control device, in particular, an electrode and a workpiece that are opposed to each other with a machining gap interposed therebetween, and which performs sampling, calculation, and hold functions for the machining gap. This may relate to an electrical discharge machining control device controlled by a position control servo system [Prior art] General VC discharge W1. The pass-port system of a processing machine is required to quickly control 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 electrode drive device, and in order to control the machining interval i, a position with sampling, logic, and Attempts have been made to apply a control servo system. This position control servo system 1c uses a general-purpose processing system such as a microprocessor or a minicomputer.

This kind of electrical discharge machining side? As an A3 device, one shown in FIG. 8 has been proposed.

That is, a machining gap α4 is formed between the machining tti(lo) and the workpiece @, and electric discharge machining is performed by applying a current-controlled pulse voltage from the power source α0 to this machining gap α4.

(To) is a determination circuit that measures the discharge wL start time after applying a pulse voltage to the machining gap α4 until the discharge starts, and determines whether this is shorter than a predetermined first time. a time domain, a second time domain that is longer than the first predetermined time and p shorter than the second predetermined time; and an eighth time domain in which discharge does not occur for more than the second predetermined time or during the application time of the pulse voltage. A servo signal for narrowing or widening the machining gap α4 is output based on which of the two types it belongs to. Among these servo signals, only the up signal SU and the DOWN signal SD shown in FIG. and (c), obtain the AND outputs shown in FIG.
The up signal SU and the Dhawan signal SD within the predetermined time are supplied to
Find the ratio 4'It.

The counter is reset by a reset signal SRK obtained every 37 hours corresponding to the sampling period from a logic operation circuit (described later). Therefore, the counter 28 is configured as shown in FIG. It is subtracted and reset at time t4 when ΔT time elapses.

Repeat the above operations every 37 hours.

The count output of the counter is fed into the register)
This register (g) is stored by the set signal SS shown in the diagram 'tJ112 obtained immediately before the reset signal SR from the arithmetic port f) (c).

The integral signal of the servo signal stored in the register (2) is converted into a spindle position lit command value according to the pole rWJ voltage by a device member having the functions of sampling, logical operation, and holding.

The device (to) is supplied with an input latch (to) that receives the output of the register (to), the output of this latch and the output of an error force output (to) to be described later, and is supplied with a reset signal SR and a set signal SS of a predetermined period. ? Logical operation circuit (goods) that outputs
And this time v! A threshold value is collected from the output latch 34 that holds the output of r (goods). logic operation circuit hh,
Read the tracking error z6 between the output of the error counter (to), that is, the zero-order hold output Zc of the latch ■, and the spindle position detection signal Zf, and add this to the entire spindle position command list, and the resulting command room is the output latch diagram. until the next command room is output.

The command 1i1fI held by the output latch is supplied to the error counter (to) of the 1st position servo No. 7; A position error signal Zε subtracted by a signal Zf representing .

The position error signal 2ε of the error counter (to) is converted into an analog signal by the D/A converter, and then sent to the speed amplifier (6).
It is supplied as a speed command to the drive speed control servo system of the electric kettle (a), which is composed of a DC servo motor and a finger speed generator, and drives the DC servo motor (b) to generate the ball screw (
9) is rotationally driven to move the main @ wheel that fixes the electrode (6) fully forward and backward, and the Lff flow is rotated until the displacement of the pin axis becomes equal to the position command. 04 Maintain all qualifications.

[Problem that the invention seeks to solve]

According to the above conventional device, after applying a pulse voltage to the machining gap α4, is there a discharge? ! - It is possible to maintain the machining gap α4J at an appropriate value by detecting the time until the start with the discriminating circuit (to), but the sump 1vfIt
The temporal change in the servo signal input to the control system is shown in Figure H in $2.
In this control method, the feed gain G of the spindle is determined by G = KSj - (K is a constant), but the response time of one mechanical system is slow compared to the time for changing the state between the poles. From restrictions.

Particularly in the finishing area, follow-up control may not be possible and the machine may fall into an oscillating part, and machining performance often has to be reduced.

The present invention has been made to solve the conventional problems mentioned above, and has achieved servo control with good followability by controlling the spindle feed gain as a function of the differential slope of the servo signal between two poles. An object of the present invention is to provide an electrical discharge machining control device that can improve machining efficiency in a stable machining region at all times in the machining state.

[Means for solving problems]

In the electric discharge machining system according to the present invention, the electrode and the workpiece are opposed to each other through the machining gap, and a controlled bus voltage is applied to the machining gap until electric discharge occurs. electric discharge machining control comprising: a determination circuit that measures the required discharge start time and outputs all servo signals to adjust the machining gap; a position control servo system that performs the machining amount Pjl-servo control based on the servo signal of the determination circuit; In the apparatus, the servo signal of the discrimination circuit is supplied to an updawan quanta that integrates at a predetermined period corresponding to the sampling period, and the servo signal of the updawan kawanta [[? The output a of the register is supplied to the register for each predetermined period.
V, the main shaft feed gain is controlled as a function of the difference between the outputs of the register so as to reduce the main transport p gain when the difference is greater than or equal to the set ring.

When the spindle feed gain is equal to or less than the setting I, it is supplied to a spindle feed gain control device that controls the spindle feed gain to a predetermined spindle feed gain, and the output of the spindle feed gain control device is fed to the position control servo system.

[Operation] In this invention, the spindle feed gain is controlled as a function of the differential servo signal between poles. All corresponding parts have the same reference numerals, and a detailed explanation thereof will be omitted. 1 In the present invention, the main shaft is attached between the register (7) and the input latch of the device Feed gain control bag [(trans) is inserted into the constituent notes. This spindle feed gain control device @.

The set signal SS of the logic operation circuit (c) is supplied, and if the difference between the output signals from the register (to) is larger than a preset setting ring for each required period, the register is set so as to reduce the spindle feed gain. The spindle feed gain is controlled as a function of the difference between the outputs of the spindle and the spindle feed gain, and when the spindle feed gain is smaller than the set ring, the spindle feed gain is controlled slightly by a predetermined value.

Next, to explain the operation of the above-mentioned device of the present invention, as in the case of FIG. 8, the Aride signal SU and the DOWAN signal SD shown in FIG. (1) and - are supplied.

The AND outputs shown in FIG. 2C and D are obtained from these outputs, and these are integrated over a predetermined period of time. The count value of the counter (to) every predetermined time is stored in the register (to) and output to the spindle feed gain control device 62. After that, the same operation is repeated, and the current output box of the register (company) and its u! If the difference between the Itl output range and the output range is larger than the set ring, the main shaft feed gain is controlled as a function of the difference between the register output ranges so that the main transport gain is reduced, and the difference between the register output ranges is smaller than the set ring. In this case, the servo signal that controls the spindle feed gain to a predetermined position is output to the control system.

This servo signal is first converted into a spindle position command value according to the inter-electrode voltage by a device (2) having sampling, logical operation, and hold functions. Here, the logical operation circuit 2 calculates the difference (following error) Zgt-d between the output of the error counter (total), that is, the zero-order hold output Zc and the position detection signal Zf, and adds it to the spindle command value and calculates the difference in the first-order minute time. Calculate all zero-order hold outputs. By this operation, even in zero-order hold control in the position servo system, it is possible to perform a safe closed μm loop of the position, and high-precision gap control is possible. Since the zero-order hold output is preset as parallel data to the error counter (to) at every predetermined minute time, the output of the error counter (to) becomes an impulse output at the time of presetting. As a result, sufficient starting torque can be generated for the DC servo motor, and the entire servo system can be configured with good responsiveness. In addition.

The magnitude of the in /

Needless to say, it is set to a value that does not cause overshoot.

〔Effect of the invention〕

As described above, according to the present invention, the servo signal from the discrimination circuit that discriminates the entire state of the machining gap is supplied to the adder unit that integrates it at a predetermined period corresponding to the sampling period, and the count [ In addition to the digital/L/@ minute circuit held in all registers, the spindle feed gain control device #J''r is added to the spindle feed gain control device for each predetermined cycle, and the servo control during the sampling interval is Stable servo signal sampling is possible over the entire time domain without completely ignoring the signal.
Also, the output of the zero-order hold circuit that outputs the position control command to the position servo system is reset, and is supplied to the error counter that outputs the difference with the electrode position signal, and the output of the counter is output to the speed servo system. D/A strange 11! Even with zero-order hold control, it is possible to achieve a completely closed loop at one position, and even with an electric discharge machine with a sump YW control system, it is possible to accurately detect the machining gap shape. With what you can do. Based on the detection result, servo control with extremely good followability corresponding to the machining gap state can be performed, and machining performance can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an electrical discharge machining control device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the conventional electrical discharge machining control device and the present invention, and FIG. 3 is a block diagram of a conventional electrical discharge machining control device.
-J diagram. In the figure, αq is processed! pole, (2) is the workpiece, α4 is on the verge of discharge, (to) is the discrimination circuit, cd is the ethical calculation circuit, (to)
is an up-down counter, (to) is an error counter, C
314u D/A converter and (9) a DC servo motor. Note that the same reference numerals in Figure 0 indicate the same or equivalent parts.

Claims (1)

[Claims] A servo that aligns an electrode and a workpiece with a machining gap in between, applies a controlled pulse voltage to the machining gap, measures the discharge start time required for electric discharge to occur, and adjusts the machining gap. In an electric discharge machining control device having a discriminating circuit that outputs a signal and a position control servo system that servo-controls the machining gap based on the servo signal of the discriminating circuit, It is supplied to an up-down counter that integrates at a predetermined period, and is supplied to a register that holds the count value of the up-down counter at each predetermined period, and the difference between the output values of the register at each predetermined period is determined to be within a predetermined setting range. An electric discharge machining control device characterized in that the power is supplied to a spindle feed gain control device that changes and controls the gain so that the gain becomes zero, and the output of the spindle feed gain control device is fed to the position control servo system.