JPH02274428A - Electric discharge machine - Google Patents

Abstract

PURPOSE:To increase a machining speed by connecting one part of a shield to its other part by a lead wire and forming a loop by the shield and the lead wire. CONSTITUTION:A machining current is supplied to a mashining electrode E and a workpiece W from a power supply through a core wire 11 of a coaxial cable 10, while a loop is formed by a shield 12 and a lead wire 21 by connecting one part of the shield 12 to its other part, of the coaxial cable 10, by the lead wire 21. In this way, a machining speed can be increased, and power consumption of machining can be decreased when the machining speed is equal.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electric discharge machine.

[Prior Art] As shown in Fig. 4, a conventional electric discharge machine has a power supply
An electric discharge machining current is supplied from O to the machining electrode E and the workpiece W via the diode D, the transistor TO1, and the coaxial cable CC.

A power supply device having a power supply PSO, a diode D, a transistor TO, etc., and a main body of an electric discharge machine having a machining electrode E, a workpiece W, etc. are connected by a coaxial cable CC. The coaxial cable CC reduces the inductance between the power supply device and the electrical discharge machine main body, thereby improving the machining speed.

[mB to be solved by the invention] In the above-mentioned conventional device, in the electrical discharge machine main body, the work W
There is a part where the and processing electrode E are separated, and the coaxial cable CC cannot be used in this part, and a single wire SW is used in this part. In particular, in the area between the machining electrodes E and the work W, it is necessary to use a single wire SW.

When the machining current flows, induced inductance is generated in the above-mentioned middle &lSW, and due to this inductance, the rise of the discharge machining current waveform is poor, the peak value of the discharge current is small, and the machining speed is reduced. There's a problem.

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

Furthermore, as the overall shape of the electric discharge machine becomes larger, the single wire SW becomes longer, so the machining speed gradually decreases. Therefore, the performance such as the machining speed changes depending on the shape of the electric discharge machine and is not constant. There's a problem.

The present invention can increase the machining speed, reduce the power consumption at the same machining speed, and even if the shape of the electric discharge machine changes, the machining speed remains constant. The purpose is to provide a certain electric discharge machine.

[Means for Solving the Problems 1] The present invention supplies a machining current from a power source to a machining electrode and a workpiece through a core wire of a coaxial cable, and also connects a part of the shield of the coaxial cable to another part of the shield. They are connected by a conductive wire, and a loop is formed with the shield indicated by -h and the conductive wire.

[Function] The present invention supplies a machining current from a power source to a machining electrode and a workpiece through a core wire of a coaxial cable, and also connects a part of the shield of the coaxial cable and another part of the shield with a conductor. , since a loop was formed with the above shield and the above conductor.

The machining speed can be increased, and the power consumption can be reduced at the same machining speed, and even if the shape of the electric discharge machine changes, the machining speed remains constant.

[Example] FIG. 1 is a circuit diagram showing one embodiment of the present invention.

In this embodiment, the core wire 11 of a coaxial cable 10 is used instead of the single wire SW of the conventional example, and the tip 13 and rear end 14 of the shield 12 of the coaxial cable 10 are connected as lead wires.
21, and a variable resistor 20 in series with this lead wire 21.
is connected.

In this case, the core wire of the coaxial cable CC is connected to the workpiece W, and between the shield of the coaxial cable CC and the processing electrode E,
It is connected by the core wire 11 of the coaxial cable 10.

The transistor To is repeatedly turned on and off at a predetermined timing in order to send a predetermined electric pulse to a gap between the electrode E and the workpiece W. Variable resistor 2
0 is for adjusting the value of the current flowing through the shield 12. Note that the lead wire 21 is an example of a conducting wire.

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

When performing electric discharge machining on the workpiece W, the transistor TO is configured to apply an electric pulse between the machining electrode E and the workpiece W according to the state of the machining gap, the material of the workpiece W, the machining speed, the state of the machining fluid, etc. Repeat on and off.

Then, when the pulse of the transistor TO is turned on and discharge is started, a machining current flows from the coaxial cable CC toward the machining electrode E, and the machining current l flows through the core [11] of the coaxial cable 10.

At this time, as shown in FIG. 3, the processing current I flowing through the core wire 11 of the coaxial cable 10 causes the shield to
Since the shield 12 forms a loop via the lead wire 21 and the resistor 20, an induced current i flows due to the induced voltage. Further, the direction of this induced current i is opposite to the direction of the machining current I.

At this time, the rise of the waveform of the machining current I becomes better and steeper than in the conventional example shown in FIG. 4), the peak value of the machining current I increases, and the machining speed improves. Furthermore, in order to process at the same speed as the conventional example shown in FIG. 4, the voltage of the power source PSO can be lowered, and therefore power consumption can be reduced.

The reason why the peak value of the machining current increases by using the coaxial cable lO instead of the 5 single wire SW and forming a loop with its shield 12 as a part as described above is due to the power supply around the machining electrode E. This is because the inductance value of the wire (coaxial cable 10) is smaller than the inductance value of the single wire SW in the conventional example.

Furthermore, the length of the part where single wire SW was conventionally used (the third
By adjusting the axial length Ll of the shield 12 with respect to the length shown as L2 in the figure, the inductance value of the part used in place of the conventional single wire SW (coaxial cable 18 and the single wire part) can be adjusted. can be adjusted. Therefore, in the largest shape electrical discharge machine, the single wire S
It is possible to match the inductance value of the part used in place of W to the inductance value of an electrical discharge machine of another size. This makes it possible to unify the machining speed even if the electric discharge machines have different sizes. Moreover, conventionally, the inductance value of the single-wire SW portion was decreased by increasing the number of single-wire SWs, but according to the above embodiment, the inductance value can be adjusted without increasing the number of coaxial cables. I can do it.

A fixed resistor may be used instead of the variable resistor 20 of the above embodiment, or the variable resistor 20 and the fixed resistor may be omitted, and as shown in FIG.
1 may form a loop.

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

Furthermore, other switching elements may be used in place of the transistor TO.

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

[Effects of the Invention] According to the present invention, the machining speed can be increased, and at the same machining speed, the power consumption can be reduced, and furthermore, the shape of the electric discharge machine can be changed. This also has the effect of keeping the machining speed constant.

Figure 3

[Brief explanation of 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. lO...Coaxial cable. 11... Core wire. 12... Shield, 21... Lead wire. Patent applicant: Sodick Co., Ltd. Same agent Arata Yokubo - Figure 4

Claims (2)

[Claims] (1) An electrical discharge machine that supplies machining current from a power source to a machining electrode and a workpiece through the core wire of a coaxial cable consisting of a core wire, a shield, and an insulating material that insulates these, a part of the shield. and another part of the shield are connected by a conductor, and the shield and the conductor wire form a loop. (2) An electrical discharge machine according to claim (1), characterized in that a resistor is provided in the loop.