JP2720680B2 - Electric discharge machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machine which variably controls a rising characteristic of a discharge current value and which can maintain a constant discharge pulse energy during electric discharge machining.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram showing a typical conventional electric discharge machining apparatus. In the drawing, reference numeral 1 denotes a DC power supply circuit. A DC voltage from the DC power supply circuit 1 is turned into a pulse voltage by a switching element 3 that is turned on and off by a pulse control circuit 2, applied between an electrode 5 and a workpiece 6 via a resistor 4, and generated. Machining is performed by intermittent discharge.

[0006] Here, by sequentially supplying a current to the switching element 3 and the resistor 4 in parallel at the time of the rise of the current, the switching element 3 and the resistor 4 can be increased stepwise as shown in FIG. That is, the rising speed of the discharge current is reduced, and the consumption of the electrode 5 is reduced. Such a method is already disclosed in Japanese Patent Publication No. 56-41367.

[0004]

However, in the above method, as shown in FIGS. 6 (b), 6 (c) and 6 (d), the discharge pulse energy differs every time depending on how the discharge current value rises. For this reason, there has been a problem that the electric discharge machining surface is difficult to be uniform.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric discharge machine in which the surface roughness is uniform in an electric discharge machine with less electrode wear. .

[0006]

Means for Solving the Problems The electric discharge machining apparatus according to the present invention, the electric discharge machining apparatus for variably controlling the rising characteristics of the discharge current value during discharging current application, count the time required for the specified peak value of the discharge current circuits and, above circuit
By time and discharge current specified peak value
Set the discharge extension time to the specified timetable
Be prepared .

[0007]

[0008]

[0009]

The electric discharge machining apparatus according to the present invention is capable of regulating a discharge current.
A circuit that counts the time required to reach a constant peak value
It corresponds to the counted time and the specified peak value of the discharge current.
Timetable set to indicate the extended discharge time
Control to extend the application time of the processing pulse .

[0010]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG.
In the circuit 7 for counting the time required for the specified peak value of the discharge current, required at that time and the discharge time setting
Depending on the electrode material and workpiece material,
The discharge extension time is set for each specified peak value and the
It is a timetable 8 to be input .

[0011] Next, a description will be given of the operation. After the discharge starts,
The time detected by the circuit 7 that counts the time required to reach the specified peak value of the discharge current, that is, the discharge extension time A shown in FIG. Is output. The pulse control circuit extends the discharge time according to this time. Thus, no matter how the current rises, the discharge energy can be made constant every time by the time table for the rise time and the specified peak value.

Embodiment 2 FIG. Alternatively, in FIG. 2, by adding an integrator 9 for maintaining the current value up to the specified peak value of the discharge current in FIG. 1, the discharge energy up to the specified peak value can be calculated more accurately. Can be.

As described above, the integration amount calculated by the integrator 9 which holds the current value of the discharge current up to the specified peak value, C in FIG. 4B, is transferred to the time table for each specified peak value to discharge. For an extended time, B in FIG. 4B is output. This makes it possible to make the discharge energy constant each time more accurately than in the first embodiment.

Embodiment 3 FIG. In FIG. 3, a circuit 7 counts a time required to reach a specified peak value of the discharge current, an integrator 9 holds a current value up to the specified peak value of the discharge current, and holds a current amount after a preset discharge time. The integrator 10 is a logic circuit 11 for comparing these integrated values.

FIG. 4 shows the integral obtained by the integrator 10 which holds the current value up to the specified peak value of the discharge current.
C of FIG. 4B is passed to the logic circuit, and is compared with D of FIG. 4B obtained by the integrator 11 holding the current value after the preset discharge time. When the two integrated values become equal, the logic circuit issues an OFF command to the pulse control circuit. This makes it possible to more accurately make the discharge energy constant each time.

[0016]

As described above, according to the present invention, the discharge
Circuit that counts the time required for the specified peak value of the flow
By time and discharge current specified peak value
The discharge extension time is set according to the timetable specified.
Is controlled to extend the application time of the machining pulse.
In the past, only a certain level of control was possible,
Can be controlled arbitrarily by changing the value of the
It can be implemented at low cost. In addition, processing speed and short
Change the timetable according to the
Time table values based on the surface roughness obtained.
Can be controlled by changing the electric discharge machining surface, and the electric discharge machining surface roughness can be made uniform without variation in the control.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the present invention.

FIG. 3 is a configuration diagram showing another embodiment of the present invention.

FIG. 4 is a waveform chart for explaining the operation of the present invention.

FIG. 5 is a configuration diagram showing a conventional electric discharge machine.

FIG. 6 is a waveform diagram of a conventional electric discharge machine.

[Explanation of symbols]

5 Electrode 6 Workpiece 7 Discharge time detection circuit 8 Time table 9 Integrator holding current amount up to specified peak value of discharge current 10 Integrator holding current value after specified time of discharge current 11 Logic circuit

Claims (1)

(57) [Claims] 1. An electric discharge machining apparatus which variably controls a rising characteristic of a discharge current value while a discharge current is flowing, counts a time required until a specified peak value of the discharge current.
That circuitry and, defined peak of the discharge current and the counted time by the circuit
Set the discharge extension time according to the
Electric discharge machining apparatus being characterized in that a bull.