JPS5921733B2 - Electric discharge machining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machining method, and particularly to generation of machining pulses, in which the pulse width τ of a short machining unit is used.

n. s and the interval τ. Generate pulses of a group of unit pulses with ff, s, and the width τ of the pulse group. n and interval τo
The present invention relates to an improvement of an electric discharge machining method that processes by repeating a pulse train having ff. A group of such unit pulses has a composite pulse width τ.

Even if n becomes long, the pulse width τ for a short machining unit. n,s
Because it is a collection of unit pulses, the machined surface has good roughness and precision machining is possible, arcing etc. can be prevented by interrupting the group, stable machining is possible, and machining with extremely high machining speed and efficiency is possible. effective. However, the present invention has been proposed to further improve this and improve processing efficiency, and is characterized by controlling the power density of a group of unit pulses to change over time.

The present invention will be explained below with reference to the drawings.

In FIG. 1, 1 is a machining electrode, 2 is a workpiece, and a machining gap is formed by opposing each other. Reference numeral 3 denotes a power source for supplying machining power, which is connected in parallel to the machining gap via a switch 4 such as a transistor.

The on/off switching of the switch 4 controls the power supply 3 on and off to apply pulses to the machining gap. 5 is a resistance circuit that controls the peak value lp of the pulse current.

Normally, the circuit resistance is controlled by the number of parallel operating transistors constituting the switch 4, and the peak value is changed and controlled. 6 is the required pulse width τ.

n and the interval τ. For example, a multivibrator is used as an oscillator that generates pulses corresponding to a pulse group having ff. T is the extremely short pulse width τ. n, s, interval τ. f
This is an oscillator for generating unit pulses having f·, s, which generates a group of unit pulses by combining with the output of the oscillator 6, and this output pulse is applied to the switch 4 for on/off control and processing. Machining is performed by electrical discharge by supplying a pulse train to the trench. The machining performance of electrical discharge machining is τ of the machining unit.

0.8, τ0ff.3, and the width τ of a group of unit pulses.

o, interval τ. It changes depending on Ff etc. That is, the machining speed increases in proportion to the discharge energy, and the machined surface roughness deteriorates in proportion to the discharge time. Also, the electrode extinction ratio is the discharge duration τ. This can be reduced by increasing o, and by appropriately selecting the discharge time depending on the electrode material, almost no consumable machining can be achieved. From this point, empirically τ0
0, τ0ff, etc. are set. Also, the power unit pulse that determines the machined surface roughness, etc. is τ. 0.8 is 1~10QμS, τ
0ff. , is selected and set in a range of about 10 to 50 μs.

Therefore, as described above, the present invention temporally controls the unit pulses constituting each group so that the power density of each group is controlled to change over time, so that an optimal pulse train is generated and repeated. 8 is a control circuit for the oscillator 7 that generates unit pulses.

Activated by the output of an oscillator 6 which generates pulses corresponding to a population of time duration τ. The oscillation state of the oscillator 7 is controlled within o to change the unit pulse temporally. The change control is the pulse width τ of the unit pulse. 0.8, interval τ.

Ff. , , or control the number of repetitions f-s. In FIG. 2, A indicates the unit pulse interval τ0ff. 8 is controlled gradually from the beginning to the end of the group, and in this case, the power density of each group is controlled to be high at the beginning and low at the end.

In this case, stability is improved especially when processing iron materials.
Of course, in some cases the unit pulse interval τ may be the opposite.
Ff. 8 may be controlled to be gradually shorter so that the power density of each group is low at the beginning and high at the end. A control circuit 9 controls the resistor circuit 5 to temporally change the peak value 1p of the unit pulse.

The peak value 1p control of the unit pulse by the control circuit 9 may be performed by temporal increase control as shown in Figure 2, or decrease control as shown in Figure 2, or the time width τ as shown in Figure 2. Control may also be performed such that it increases in the middle of o and decreases at the beginning and end. When such control is performed, it is particularly effective when processing Ni-based materials, and processing can be performed with less electrode wear. In this way, the present invention has an extremely short processing unit pulse width τ.

0.5 and the interval τ.

Ff. Generate a group of unit pulses with width τ.
o and the interval τ. In electric discharge machining that generates a group having Ff, the power density of each group is controlled to change over time by unit pulse control, so that a group of pulses that is optimal for the machining conditions is always generated. The machining speed can be further increased, the machined surface roughness can be improved, and high precision machining can be performed with less electrode wear.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. 2 is a waveform explanatory diagram. 1 is an electrode, 2 is a workpiece, 3 is a processing power source, 4 is a switch, 5 is a resistor circuit, 6 is a pulse oscillator, 7 is a unit pulse oscillator, 8 is a unit pulse control circuit, and 9 is a peak value control circuit. .

Claims (1)

[Claims] 1. In electrical discharge machining in which machining power from a machining power supply is applied as pulses by a switch to a machining gap formed by opposing machining electrodes and a workpiece, a pulse oscillator is used to set the required pulse width τon and interval τoff. , a unit pulse oscillator that oscillates a unit pulse having a pulse width τon·s shorter than the pulse width τon and an interval τoff·s within the pulse width τon generated by the pulse oscillator, and a pulse width τ·s generated by the unit pulse oscillator. It consists of a control circuit for a unit pulse oscillator that changes the on・s and interval τoff・s, and a peak value control circuit that changes the height of the peak value 1p in one or more of the unit pulses, Set the pulse width τon and the interval τoff, and from the unit pulse oscillator within the set pulse width τon,
The pulse signal oscillates while changing the unit pulse width τon・s and interval τoff・s under the control of the control circuit of the unit pulse oscillator, and the power density and waveform of the processing pulse are determined based on the signal of the peak value control circuit. An electric discharge machining method characterized by controlling a high value.