JP2869538B2 - Discharge current supply device for electric discharge machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge current supply device for an electric discharge machine, and more particularly, to connecting a power supply device and a main body of the electric discharge machine with a coaxial cable, and using the coaxial cable. The present invention relates to a discharge current supply device in which a power supply line formed of a coaxial cable connects between a power supply and an electrode or a work.

[Prior Art] In a conventional machining current supply device of an electric discharge machine, for example, as shown in FIG. 4, a power supply PS0 supplies a machining electrode E and a work W via a diode D, a transistor T0, and a coaxial cable CC. Devices configured to supply an electrical discharge machining current are known.

A power supply device having a power supply PS0, a diode D, a transistor T0, and the like, and an electric discharge machine main body having a machining electrode E, a work W, and the like are connected by a coaxial cable CC. The coaxial cable CC reduces the inductance between the power supply device and the electric discharge machine main body, thereby improving the machining speed.

[Problems to be Solved by the Invention] However, since the electrode E and each power supply terminal of the work W are located to some extent, the end of the coaxial cable CC on the processing machine main body side remains in the coaxial cable shape. In fact, it cannot be connected to the electrode E and the work W. That is, in the gap between the machining electrode E and the work W, a single wire SW must be used for connection with either the electrode E or the work W.

Then, when the machining current flows, an induction inductance is generated in the single wire SW, and due to this inductance, the rising of the discharge machining current waveform is poor, the peak value of the discharge current is small, and therefore, the machining speed is reduced. There's a problem.

Further, in order to increase the processing speed, it is necessary to increase the power supply voltage, which causes a problem of increasing power consumption.

Furthermore, as the size of the electric discharge machine becomes larger,
Since the length of the single wire SW must be increased, when a power supply device having the same power supply voltage is connected, the machining speed becomes slower as the size of the electric discharge machine becomes larger. Therefore, there is a problem that the performance such as the machining speed changes depending on the shape of the electric discharge machine and is not constant.

According to the present invention, the machining speed can be increased, and if the machining speed is the same, the power consumption can be reduced.Also, even if the shape of the electric discharge machine changes, the machining speed is constant. It is an object of the present invention to provide a discharge current supply device for a certain electric discharge machine.

Means for Solving the Problems The present invention includes an electric discharge machine main body, a machining power supply device, and a first coaxial cable connecting a power output of the machining power supply device to the electric discharge machine main body, In a discharge current supply device of an electric discharge machine in which one end of one of a core wire and a seal wire at the end of the coaxial cable at the main body side of the electric discharge machine is connected to the work side, The end of the other line at the EDM body side end is
A second coaxial cable connected to the electrode side via one of the core wire and the shield wire, and a loop circuit including a conductive wire connecting both ends of the other wire of the second coaxial cable. It is a discharge current supply device of an electric discharge machine having the above.

[Operation] According to the configuration of the present invention, an induced voltage is generated in the other line by the discharge current flowing in one line of the second coaxial cable, and both ends of the other line of the second coaxial cable are connected. A current in a direction opposite to the discharge current flowing through the one line flows through the loop circuit including the conductor. By the action of the current in the opposite direction, the inductance of the circuit formed by the one line is reduced, and the lowering of the peak value of the discharge current is more effectively prevented. Further, according to this configuration, it is possible to connect the coaxial cable as much as possible in the vicinity of the gap, thereby improving the machining speed, and further reducing the power consumption when performing the electric discharge machining at the same machining speed. be able to.

Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In this embodiment, the core wire 11 of the coaxial cable 10 is used instead of the conventional single wire SW, and the shield of the coaxial cable 10 is used.
The end 13 and the end 14 of 12 are connected by a lead wire (conductor) 21,
The variable resistor 20 is connected in series with the lead wire 21.

In this case, the core wire of the coaxial cable CC is connected to the work W, and the space between the shield of the coaxial cable CC and the processing electrode E is
The coaxial cables 10 are connected by a core wire 11.

The transistor T0 is repeatedly turned on and off at a predetermined timing in order to supply a predetermined voltage pulse to a gap between the electrode E and the work W. The variable resistor 20 adjusts the value of the current flowing through the shield 12. Note that the lead wire 21 is an example of a conductive wire.

 Next, the operation of the above embodiment will be described.

When electric discharge machining is performed on the work W, the state of the gap, the work W
The transistor T0 is repeatedly turned on and off so as to apply a voltage pulse between the processing electrode E and the work W according to the material, the processing speed, the state of the processing liquid, and the like.

When the transistor T0 is turned on and a voltage pulse is applied between the poles to generate a discharge, a pulsed discharge current flows between the poles via the coaxial cable CC, and the discharge current I flows through the core wire 11 of the coaxial cable 10. .

At this time, as shown in FIG. 3, an induced voltage is generated in the shield wire 12 by the discharge current I flowing through the core wire 11 of the coaxial cable 10, and this shield wire 12 is connected via the lead wire 21 and the resistor 20. Since the loop is formed, the induced voltage causes the induced current i to flow through the loop circuit, and the induced current i is opposite to the discharge current flowing through the core wire 11 in the shielded wire 12 of the coaxial cable 10.

Therefore, the circuit inductance of the core wire 11 of the coaxial cable 10 is smaller than the circuit inductance of the single wire SW shown in FIG. 4, and the rise of the waveform of the discharge current I is improved (sharper), and the discharge current I , And the processing speed is improved. To process at the same speed as the conventional example shown in FIG.
Can be reduced, and therefore power consumption can be reduced.

As described above, the reason why the peak value of the discharge current I is increased by using the coaxial cable 10 instead of the single-wire SW and forming a loop with the shield 12 as a part is as follows.
This is because the inductance value of the power supply line (coaxial cable 10) connected between the machining electrode E and the coaxial cable CC and wired around the electric discharge machine main body is smaller than the inductance value of the single wire SW in the conventional example.

Furthermore, the length of the part where the single wire SW was used conventionally (No. 3
By adjusting the axial length L1 of the shield 12 with respect to the length shown as L2 in the figure, the inductance value of the portion (coaxial cable 10 and single wire portion) used instead of the conventional single wire SW Can be adjusted. Therefore,
It is possible to match the inductance value of an electric discharge machine of another size to the inductance value of the portion used instead of the single wire SW in the largest shape electric discharge machine. As a result, even if the size of the electric discharge machine is different,
The processing speed can be unified. Moreover, conventionally, the value of the inductance of the portion of the single wire SW was reduced by increasing the number of the single wire SW. Can be.

A fixed resistor may be used in place of the variable resistor 20 of the above embodiment, and the variable resistor 20 and the fixed resistor are omitted, and as shown in FIG. And may form a loop only.

Note that the coaxial cable 10 and the lead wire 21 or the coaxial cable 10 and the lead wire 21 and the resistor 20 as described above may be used between the core wire of the coaxial cable CC and the work W.

Further, another switching element may be used instead of the transistor T0.

Further, a portion connected to the core wire of the coaxial cable CC may be connected to the shield, and a portion connected to the shield may be connected to the core wire.

[Effects of the Invention] According to the present invention, the machining speed can be increased, and if the machining speed is the same, the power consumption can be reduced. Further, the shape of the electric discharge machine changes. Also,
There is an effect that the processing speed can be kept constant.

[Brief description of the drawings]

 FIG. 1 is a circuit diagram showing one embodiment of the present invention. FIG. 2 is a circuit diagram showing another embodiment of the present invention. FIG. 3 is an explanatory diagram of the operation in the above embodiment. FIG. 4 is a diagram showing an example of a conventional electric discharge machine. 10 ... coaxial cable, 11 ... core wire, 12 ... shield, 21 ... lead wire.

Claims (2)

(57) [Claims] An electric discharge machine main body, a machining power supply device, and a first coaxial cable for connecting a power output of the machining power supply device to the electric discharge machine main body, wherein the electric discharge machining of the first coaxial cable is performed. A discharge current supply device for an electric discharge machine, wherein an end of one of a core wire and a shield wire at an end of the electric machine main body is connected to a work side; And a second coaxial cable connected to the electrode side via one of the core wire and the shielded wire; between the two ends of the other wire of the second coaxial cable. And a loop circuit including a conducting wire for connecting the discharge current to the discharge current supply device. 2. The electric discharge machine according to claim 1, wherein a resistor is provided in series in a loop circuit connecting both ends of the other line of the second coaxial cable. Discharge current supply device.