JPS61219520A - Electric discharge machine - Google Patents

Abstract

PURPOSE:To increase the number of discharge pulses within a certain time and improve machining efficiency by closing a switching element by means of a pulse generated at every set time in accordance with a machining condition and applying voltage between electrodes in an electric discharge machine. CONSTITUTION:A field-effect transistor 5 as a switching element is provided in the electric discharge driving circuit of an electric discharge machine. The transistor 5, is connected to a discharge passage between a part between a wire electrode 4 and a workpiece electrode 2 and a DC power source 1, opens and closes the discharge circuit to generate discharge in a machining gap G, and applies voltage between both electrode 2, 4 from the power source 1. And, a current detecting circuit 9 detects a discharge which is carried out between both electrodes 2, 4 with the transistor 5 being turned on, and generates a detecting signal. And, further, a first delaying means which outputs an operating signal based on the detecting signal of the circuit 9, means of generating a pulse signal regardless of the detecting signal, and a switching control means which controls the transistor 5 as the switching element are provided.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention is a method for machining a workpiece by utilizing a discharge phenomenon when a voltage is applied between a workpiece electrode and a discharge electrode. Regarding electric discharge machines.

``Prior art'' In order to stably repeat electric discharge in wire-cut electric discharge machining, it was thought that a necessary and sufficient discharge body dwell time was required for each discharge (Japanese Patent Laid-Open No. 56-89434).
issue). Patent application relating to the applicant's own earlier application 1986-1985
．． No. 193 focuses on this point.

Equipped with a programmable timer that fixes the sum of rest time and discharge time to a constant value 1. □゛ Surface roughness selection switch! Tsuchi°′
The discharge period set by 5゛ has elapsed since the start of discharge.
.

□Delay circuit that generates an off signal when
□Set by the off signal of the
- It was equipped with a 7-lip, 70-tub circuit that was set by the drive signal of the multiplex timer.

As shown in FIG. 4, it is determined by the voltage of the power supply, the size and condition of the machining gap, the no-load time TC, the surface roughness, etc.

Electric discharge machining was performed by setting the total time of the discharge time (load time) Ta and the necessary and sufficient fixed discharge body stop time Tb to -□ cycle time To, but in this conventional electric discharge machine, Since the sum of the discharge time 1°a and the discharge body stop time Tb was predetermined by the oligograph timer, machining efficiency can be improved by increasing the number of discharge pulses within the predetermined time To. I couldn't do anything.

1. , [Problems to be solved by the invention] The present invention has been made in view of the above problems.
:Discharge-(An object of the present invention is to provide an electrical discharge machine that can improve machining efficiency by increasing the number of passes.

[Means for Solving the Problems] According to the present invention, 1. a discharge electrode is connected between the electrode and the workpiece electrode on the discharge path between the electrode and the source, and the discharge is connected to the machining gap between them; The said discharge 7 electric path (
A switching element which opens and closes and applies a voltage 5 between the two electrodes from the power supply, and when the switching element is turned on, it detects that a discharge has occurred between the two electrodes and generates a detection signal. a first delay means connected to the discharge occurrence detection means and outputting an activation signal after a first set time based on a detection signal of the detection means; A pulse signal generating means that generates a pulse signal at every second set time irrespective of the detection signal of the generation detecting means and a pulse signal of the pulse signal light generating means are present, and the defense switching element is turned on. An electric discharge machine is provided which includes a switching controller stage ′ □ ° ′ for turning on a switching element based on an activation signal for a delay means ′ ′ □ □ . - “Sakuishi”
・According to the above configuration, the set time for the foreign language in which discharge is continued according to the upward surface roughness, etc. is arbitrarily set in the □-th delay/means, and □These are independent of □. Since the second setting time is arbitrarily set by the pulse signal generating means according to the plate thickness of the workpiece, etc., the discharge body time is not fixed, and in principle, it can be set according to the plate thickness and other conditions. Since a discharge pulse is generated at every second set time corresponding to , the dwell time of the discharge body is shortened and the number of discharge pulses is increased.

Examples] Next, an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a circuit diagram showing the entire discharge drive circuit of the electrical discharge machine according to this embodiment, Fig. 2 is a circuit diagram showing the relation between the discharge control circuit and the central processing unit, and Fig. 3 is the discharge control circuit. It is a timing chart of a circuit.

One end of a DC power source 1 serving as a power source is connected to a workpiece 2, and a charging capacitor 3, which also serves as a power source, is connected to a workpiece 2.
・Connected to the - pole of. In addition, a wire electrode 4 that faces the workpiece @ 2 through a machining gap G and is movable relatively.
is a field effect transistor (
(hereinafter simply referred to as FET) 5, a diode 6, a current detection resistor 7 consisting of a non-inductive resistor, and a diode 8, the wire electrode 4 is connected to the charging capacitor 3 via a PE 75. connected to the other pole. Further, a current detection circuit 9 for detecting discharge having an isolator or the like having a well-known configuration is connected to both ends of the current detection □ resistor 7, and the output signal path of the current detection circuit 9 is introduced into the discharge control circuit 10. , the output signal path of the discharge control circuit 10 is introduced into the gate terminal of the FET 5. In addition, a series circuit of a diode 11 and a resistor 12 is connected in parallel with both ends of the liquid adding material 2 and the wire electrode 4.

As shown in FIG. 2, a delay circuit 13 serving as a first delay means is connected to the current detection circuit 9. This delay circuit 13 is activated by a short pulse fFi after a set time to which corresponds to the load time after the signal is input.
This set time 1 (, is arbitrarily set by the medium heat treatment unit &(CI'U) 14 according to the operation of the surface Ju1 degree selection switch 15.Discharge control layer A programmable timer 16 is provided in the circuit 10, which generates a very short pulse signal every arbitrarily set time (discharge cycle time) ts, regardless of the detection signal of the current detection circuit 5. The programmable timer 16 serves as a pulse signal generating means, and its discharge cycle time ts is determined by the thickness of the workpiece 2, the wire diameter of the wire electrode 4, and the like by operating the keyboard 17 provided in the CPU 14. It is set according to machining conditions such as the electrical conductivity of water supplied to the machining gap G and discharge energy (time to turn off the FET 5).

The programmable timer 16 outputs the output 1 of the timer 16.
It is connected to a clock terminal CLK of a 7-lip prop (hereinafter simply referred to as FF) 18, which constitutes switching control means and which generates a high-level output signal based on a word. The output signal of the delay circuit 13 is introduced into the clear terminal CLR of the FF 18, and when the output signal of the delay circuit 13 is at a high level, the FF 18 is cleared and the output signal disappears (becomes a low level).

The output signal of the FF 18 is introduced into the date terminal of the FET 5 via an AND date 19 for controlling the start-up of the discharge control circuit 10.

"Operation" In the above configuration, a starting signal 1iso is sent to the AND gate 19.
When n is introduced, this AND date 19 is opened, and it becomes possible to give an output signal from the FF 18 of the discharge control circuit 10 to the date terminal of the FET 5.

As shown in FIG. 3, when the programmable timer 16 generates the first pulse, this pulse is transmitted to the FF 18.
clock terminal C! , is added to K.

Since the output signal of the delay circuit 13 is not generated, FF1
Since clear terminals CI and R of FET 8 are at low level, this F)'18 is set and generates a high level output signal at output terminal Q, and this output signal is sent to the gate terminal of FET5 via AND date 19. signal is applied and FET 5 turns on. Then, a voltage is applied from the DC power source 1 and the charging capacitor 3 to the liquid injector 2 and the wire electrode 4. After some no-load time has passed, discharge occurs in the discharge gap G between them, and the current detection circuit Detection signal S from 9
G is generated and applied to the delay circuit 13. Delay circuit 1
3 is the load time 1 (,
After , a pulse signal is generated for a short period of time, and this signal is applied to the clear terminal CLR of the FF 18. Since the FF 18 eliminates the output signal of the output terminal Q by applying a signal to the clear terminal CLR, the PE 75 can no longer apply a signal to the date terminal and turns off.

Then, the discharge in the discharge gap G ends after a short period of time.

When the #2 pulse is generated by the programmable timer 16 after the discharge cycle time ts, this pulse is applied to the clock terminal CLK of the FF 18, so that the FF 18 outputs an output signal to the output terminal Q at the rising edge of this pulse. PET through and date 19
Since this output signal is added to the date terminal of FE
T5 is turned on, voltage is applied to the workpiece 2 and wire electrode 4 from the DC power supply 1 and charging capacitor 3,
Discharge occurs in these discharge gaps G after some no-load time. A detection signal SG is generated from the current detection circuit 9, and a short pulse is generated from the delay circuit 13 after the load time to. The pulse of the delay circuit 13 is applied to the clear terminal CLK of FF1B, which eliminates the output signal at the output terminal Q and turns off the FET 5.

When the third pulse is generated by the programmable timer 16 after the discharge cycle time ts, in the example shown in FIG. Since terminals CI and R are at a low level, the pulse of programmable timer 16 is set by being applied to clock terminal CLK, producing an output signal at output terminal Q. Then, this output signal is applied to the date terminal of FET 5 via AND date 19, so FET 5 is turned on. At this time, after the FET 5 is turned off after a load time tD due to discharge detection, the FET 5 is turned on at an interval much shorter than the discharge cycle time ts. After that, a discharge is generated in the discharge gap G. A detection signal SG is generated from the current detection circuit 9, and the delay circuit 13 generates a pulse signal after a load time to from the rising edge of this detection signal SG, and when the pulse signal rises, the FF 18 causes the output signal to disappear. ,F
ET 5 is turned off.・Discharge cycle time ts
elapses and the fourth pulse is programmable timer 1.
6, the FF 18 is set and generates an output signal, and by adding this output signal to the date of the PET 5, the FET 5 is turned on and a voltage is applied to the discharge gap G. When a discharge occurs in the discharge gap G after some no-load time, the current detection circuit 9 generates a detection signal SG, and the delay circuit 13 generates a short pulse signal after the load time tD to clear the FF 18. Terminal CLR
Give this pulse signal to The FF 18 eliminates the output signal at the rising edge of the pulse signal of the delay circuit 13, and
Turn off ET 5.

In the darkness where there is a signal from the delay circuit 13 (high level),
When the fifth cycle time ts arrives, a pulse is sent from the programmable timer 16 to the FF18 glue/lock terminal C.
Even if the signal is input to I and K, since the output signal of the delay circuit 13 is input to the clear terminal CLR of the FF 18, the FF 18 is not set, and no output signal is output to the output terminal Q of the FF 18. Then, the FET 5 is turned on by the next sixth pulse of the programmable timer 16.

(Advantages of the Embodiment According to the embodiment described above, the load time to- of the delay circuit 13 and the cycle time ts of the programmable timer 16
are all set by the CPU 14, which has the advantage of being easy to set and requiring no consideration. However, the present invention is not limited to the configurations of the above-described embodiments. '1 Effects' As mentioned above, the electrical discharge machine of the present invention has the above configuration, and the pulses generated at every second set time set according to the machining conditions. Since the switching cable f is closed and a voltage is applied between both electrodes, the predetermined time is reduced compared to the conventional case where the discharge and rest times were fixed at necessary and sufficient values regardless of the machining conditions. This has the excellent effect of increasing the number of discharge pulses within the process and improving machining efficiency.・, □

[Brief explanation of the drawing]

li diagram is a circuit diagram showing the entire discharge drive circuit of an electrical discharge machine according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing the relation between the discharge control circuit and the central processing unit, and FIG. 3 is a circuit diagram showing the discharge control circuit. (Circuit Timing Chart) FIG. 4 is a wave/form diagram for explaining the discharge cycle in a conventional electric discharge machine. DESCRIPTION OF SYMBOLS 1... DC power supply, 2... Workpiece, 3... Charging capacitor, 4... Wire electrode, 5... Field effect transistor (FET), 7... Current detection resistor, 9・
...Current detection circuit, 10...Discharge control circuit, 13...
・Delay circuit, 14... Central processing device, ・16...
Programmable timer, 18,...7 lips, 70 knobs (FF), G...machining gap, SG...detection signal, t
o: Load time, tS: Discharge cycle time. .

Claims (1)

[Claims] A discharge electrode and a workpiece electrode are moved relative to each other, and a voltage is applied between these electrodes to generate an electric discharge in the machining gap between them, and the workpiece is moved by the discharge energy. In an electrical discharge machine for machining, switching is connected to a discharge path between the electrodes and a power source, and opens and closes the discharge path so as to generate a discharge in the machining gap, and applies a voltage between the two electrodes from the power source. an element, a discharge occurrence detection means for detecting the occurrence of discharge between the two electrodes and generating a detection signal when the switching element is turned on, and a discharge occurrence detection means connected to the discharge occurrence detection means; a first delay means that outputs an activation signal after a first set time based on a detection signal; and a pulse signal generator that generates a pulse signal every second set time regardless of the detection signal of the discharge occurrence detection means. and switching control means for turning on the switching element when a pulse signal from the pulse signal generating means is present, and turning off the switching element based on the activation signal of the first delay means.