JPH0487721A - Control method and device for wire electric discharge machine - Google Patents

Abstract

PURPOSE:To improve stability of electric discharge machining by constituting one cycle with the wait time form the time when a sub-power supply is turned on to the time when electric discharge occurs, a certain power supply time which is set in advance until supply of electric discharge energy from the main power supply is completed after electric discharge occurs, and the halt time until the sub-power supply is turned on again after that. CONSTITUTION:A sub-power supply control means 11 which constitutes a part of a pulse control device 3 is turned on by a control signal from a numerical control device 15 which is set in advance. A first predetermined time elapse detection means 12 is started, and electric discharge start detection section in the pulse control device 3 is made into the condition where detection is possible. When electric discharge is started in a clearance between a workpiece W and a wire electrode 1 after uncertain wait time elapses, pulse is output from a main power supply control means 10, and pulse width setting means which sets pulse width of the main power supply is operated. When setting of pulse width ends, the main power supply and sub-power supply control means are turned off by end signal. After this, a second predetermined time elapse detection means 14 which sets the minimum pulse halt time width is started.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method and apparatus for controlling a wire electrical discharge machine equipped with a pulse control device for applying a pulse voltage to a wire electrode of the wire electrical discharge machine. It is something to do.

[Prior Art] A conventional power supply device for a wire electrical discharge machine equipped with this type of pulse, 91 m device has a power supply device connected to the wire t8ii when the device is used to generate a pulse discharge. The waiting time from when the wire electrode is turned on until discharge occurs in the gap between the wire electrode and the workpiece, and the power supply time from when the main power is turned on after the discharge occurs until the supply of discharge energy ends. One cycle consists of the pause time from immediately after that until the sub power supply is turned on again.

However, in this case, although the power supply time and rest time can be controlled by using a counter, it is impossible to control the waiting time because it varies depending on conditions such as the gap between the wire electrode and the workpiece. Therefore, the cycle of pulsed discharge, which is the sum of the waiting time, power supply time, and rest time, differs for each pulsed discharge, making electrical discharge machining unstable.

In addition, if pulse discharges of relatively short cycles occur continuously in this unstable pulse discharge cycle, that is, if the pulse discharge frequency is high, the wire electrode may be locally damaged and the wire tffA may be suddenly disconnected. may occur.

[Problems to be Solved by the Invention] This invention stabilizes the cycle of unstable pulsed discharge that was unavoidable in the conventional power supply device for a wire electrical discharge machine, and improves the stability of electrical discharge machining using the pulsed discharge. The purpose is to

Another purpose is to prevent local damage to the wire electrode due to the unstable pulse discharge period, thereby eliminating the risk of sudden breakage of the wire electrode.

[Means for Solving the Problems] This invention solves the unstable waiting time until discharge occurs in the gap between the wire electrode and the workpiece, and the supply of discharge energy from the main power source after the discharge occurs. This is a control method and apparatus for a wire electric discharge machine, in which a so-called pulse discharge period, which is defined by a period including a power supply time until the end of the power supply and a rest time immediately after that until the sub power supply is turned on again, is made constant.

In detail, a main power source that outputs high current pulses and a sub power source that outputs low current pulses are connected in parallel between the wire wire pole and the workpiece to supply pulse current and generate electric discharge. In a wire electric discharge machine that processes a workpiece while causing the electric discharge, the waiting time from when the sub-power supply is turned on until discharge occurs, and the time required for the discharge to occur @ until the supply of discharge energy from the main power supply is terminated. A fixed power supply time set in advance,
There is provided a method for controlling a wire electric discharge machine, characterized in that the pulse discharge period is controlled to a predetermined constant time period, which includes a period of rest until the sub power source is turned on again.

In addition, a main power source that outputs high current pulses and a sub power source that outputs low current pulses are connected in parallel between the wire electrode and the workpiece, and a pulse current is supplied to the workpiece while generating electric discharge. A control device for a wire electrical discharge machine for machining a wire electrical discharge machine, comprising: a discharge start detection unit for detecting the start of discharge between the machining electrodes by a pulse current output by the sub-power supply; and a pulse width setting means for setting the discharge duration. main power supply control means for turning on the output of the main power supply in response to a discharge start signal from the discharge start detection section and turning off the output of the main power supply in response to a pulse width end signal from the pulse width setting means; first predetermined time elapse detection means for detecting the elapse of a predetermined time set longer than the pulse width after the output of is turned on;
and a second predetermined time elapse detection means for detecting elapse of a set minimum OFF time from when the predetermined time has elapsed and the output pulse of the sub power supply is OFF, Turn on the output signal of the sub power supply with the signal
There is provided a control device for a wire electric discharge machine, characterized in that the pulse control device comprises a sub-power supply control means for turning off the output of the sub-power supply in response to a pulse width end signal from the pulse width setting means. Ru.

[Operation] A preset control signal from the numerical control device turns on the auxiliary power supply control means constituting a part of the pulse control device, starts the first predetermined time elapse detection means, and restarts the pulse control device. The discharge start detection unit in the main power source is set in a detectable state, and when a discharge starts in the gap between the workpiece and the wire electrode after an irregular waiting time, a pulse is output from the main power control means and the main power source is turned on. A pulse width setting means for setting the pulse width of the power supply is activated. When the setting of the pulse width is completed, the main power supply control means and the sub power supply control means are turned off by the completion signal. Further, when the first predetermined time elapse detection means finishes counting and the sub power supply control means is in the OFF or OFF state, the second predetermined time elapse detection means for setting the minimum pulse rest time width is started. let When the second predetermined time elapse detection means finishes counting, the sub-power supply control means is turned on to return to the initial state, and then the operation is repeated, and the pulse discharge period is controlled to be constant. .

[Embodiment] An embodiment of the control device for a wire electric discharge machine of the present invention will be explained with reference to the accompanying drawings.
FIG. 3 is a block diagram showing details of the pulse control device 3 shown in the figure.

As shown in FIG. 1, a main power source 4 and a sub power source 5 are connected in parallel to each other between the feeder 2 of the wire electrode 1 facing the workpiece W with a gap C therebetween and the output side of the pulse control device 3. In the source device for a wire electrical discharge machine, the sensor 6 of the wire electrode 1 and the input side of the pulse control device 3 are connected via a gap detector 7. As shown in FIG. 2, the pulse control device W3 includes a discharge start detection section 8 that detects the occurrence of discharge between the electrodes, an M-ON counter 11 that sets the discharge duration based on the output signal of the discharge start detection section, and The number is detected by the signal of the start detection unit 8 and the M-
0N-O of the main power supply 4 by the output signal of the ON counter 11
A circuit configuration consisting of an M-ONN pulse generator 1 that controls the FF, and a TA that is activated by the state signal of the 5-ONN pulse generator that controls the auxiliary power supply 5 and sets the pulse period.
The counter 12 receives the count end signal of the TA counter 12 and the state signal of the 5-ONN pulse generator,
A 5-ON pulse OFF determining unit 13 that determines the state of the sub power supply 5; a TB that is activated based on the determination result of the 5-ON pulse OFF determining unit 13 and sets the minimum pulse rest time;
It has a counter 14, and the output signal of the TB counter 14 and the output signal of the M-ON counter 11 are used to control the output voltage of the sub power supply.
It has a circuit configuration consisting of a 5-ON pulse generating section that controls N-OFF.

In the embodiment, the pulse width setting means, the main power supply control means, the sub power supply control means, the first predetermined time elapse detection means, and the second predetermined time elapse detection means described in the claims are an M-ON counter, They are called an M-ON pulse generating section, a 5-ON pulse generating section, a TA counter, and a TB counter. The operation of this device will be explained with reference to FIGS. 1 and 2. First, the pulse control device 3
The 5-ONN pulse generator, which forms part of the
Then, a pulse voltage is applied to the wire electrode 1. At the same time, the TA counter 12 for setting the pulse period is started, and the discharge start detection section 8 is brought into a detectable state.

In this state, when a discharge starts in the gap C between the workpiece W and the wire electrode 1 after an undefined waiting time Tw has elapsed, the discharge start detection section 8 detects this, and the M-ON pulse generation section 1o is activated. After that, turn on the main power supply 4 and turn on the wire power 8i! 1 with discharge energy. At the same time, the M-ON counter 11 is activated, and when the preset count of the M-ON counter 11 is completed, the M-ON counter 11 is activated with the completion signal.
Turn off the ON pulse and 5-ON pulse. Also, the TA counter has finished counting and 5-O
If the N pulse is OFF, the TB counter 14 is started. When the TB counter 14 finishes counting, the 5-ON pulse is turned on to return to the initial state, and then the operation is repeated.

FIG. 3 is a flowchart showing the above operation, and also shows the interelectrode voltage V applied to the wire electrode l during this operation, and the 5-ON pulse generated from the 5-ON pulse generator 9.
-ON pulse v1, M-ON pulse v2 generated from the M-ON pulse generator generator, TA pulse v3 generated from TA counter 12, and TB pulse V4 generated from TB counter 12 are shown in FIG. 4, respectively. Form the waveform shown.

In this Figure 4, V. 1 is the voltage between 8i when the 5-ON pulse generator 9 in FIG. This is the voltage between the electrodes that gradually increases with the passage of time until the discharge td starts. vo is the voltage between the electrodes when the discharge d is being performed, and VO2 is the voltage between the electrodes after the discharge td is completed.

Thereafter, after the pause time 'ropt has elapsed, the voltage V between the electrodes rises again from VOI to V, and thereafter this operation is repeated to generate the pulse voltage V.

Moreover, TV is the waiting time at the door from the voltage between electrodes VOI to V peeling. Furthermore, for TON, the electrode voltage vM is ■. 2
, and T is the waiting time TV, the discharge time TON, and the rest time T. , F is the pulse discharge period consisting of a total time of F.

Then, as shown in the pulse time chart of FIG. 4, the pause time T. There is no setting for FF, and the period counter T
A and the minimum pause time counter TB are set in advance.

Further, the discharge pulse period T is set as TA+TB.

As a result, according to the present invention, even if variations in the waiting time Tw inevitably occur for each pulse discharge, the waiting times TwfJ' TA and T. When the difference is smaller than N, the discharge pulse period T is always constant.

Furthermore, when the waiting time Tw is greater than the difference between TA and ToN, the discharge pulse period is greater than or equal to T, but according to experimental results, such discharge pulses account for less than 10% of the total.
There is no practical problem with variations in the discharge pulse period.

On the other hand, as in the conventional power supply device, the downtime is
The pulse time chart when 1'P is constant is the fifth
As shown in the figure, variations in the waiting time Tw, which differ for each pulse discharge, affect the period of the pulse discharge, and as a result, the discharge machining becomes unstable.

[Effects of the Invention j This invention is as described above, and stabilizes the unstable period of pulsed discharge that was unavoidable in the conventional power supply device for wire electrical discharge machine, and improves the stability of electrical discharge machining by the pulsed discharge. can be improved.

In addition, local damage to the wire pole due to the unstable pulse discharge cycle described above is prevented, and there is no risk of sudden disconnection of the wire electrode.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a power supply device for a wire electric discharge machine according to the present invention, FIG. 2 is a detailed block diagram of a pulse control section that constitutes a part of FIG. 1, and FIG. 3 is shown in FIG. 2. FIG. 4 is a pulse time chart of the present invention, and FIG. 5 is a pulse time chart of a conventional power supply device for a wire electric discharge machine. 1...Wire electrode 2...Feeder 3...Pulse control device 4...Main power source 5...Sub power source 6... ...Detector 7...Match detection device 8...Discharge start detection section 9...5-ON pulse generation section lO...M-ON pulse generation section 11...M-ON counter 12...TA counter 13...5-ON pulse OFF determining section 14...T
B counter 15...numerical control device

Claims (1)

[Claims] 1. A main power source that outputs high current pulses and a sub power source that outputs low current pulses are connected in parallel between the wire electrode and the workpiece to supply pulse current and cause discharge. In a wire electrical discharge machine that processes a workpiece while generating electric discharge, there is a waiting time from when the sub power source is turned on until electric discharge occurs, and after the electric discharge occurs until the supply of electric discharge energy from the main power source is terminated. Wire electric discharge machining, characterized in that a pulse discharge period is controlled to a predetermined constant time, with one cycle consisting of a preset constant power supply time and a rest time until the sub power source is turned on again. How to control the machine. 2. A main power source that outputs high current pulses and a sub power source that outputs low current pulses are connected in parallel between the wire electrode and the workpiece to supply pulse current to the workpiece while generating electric discharge. A control device for a wire electrical discharge machine for machining a wire electrical discharge machine, comprising: a discharge start detection unit for detecting the start of discharge between the machining electrodes by a pulse current output by the sub-power supply; and a pulse width setting means for setting the discharge duration. and turning on the output of the main power supply with a discharge start signal from the discharge start detection section;
Main power supply control means for turning off the output of the main power supply in response to a pulse width end signal from the pulse width setting means, and detecting the elapse of a predetermined time set longer than the pulse width after the output of the auxiliary power supply is turned on. a first predetermined time elapse detection means; and a second predetermined time elapse detection means for detecting elapse of a set minimum OFF time from when the predetermined time has elapsed and the output pulse of the sub power supply is OFF. and a sub-power supply control means for turning on the output signal of the sub-power supply in response to an elapsed signal of the minimum OFF time, and turning off the output of the sub-power supply in response to a pulse width end signal of the pulse width setting means; A control device for a wire electrical discharge machine, characterized by comprising a control device.