JPS58137523A - Connection structure for feed cable of discharge work device - Google Patents

Abstract

PURPOSE:To reduce inductance of a cable by connecting one conductor of a feed cable of a wire cut discharge work machine to a wire electrode and connecting another one to the vicinity of a work section for a workpiece by means of an adsorptive contactor. CONSTITUTION:A conductor 8 of a feed cable of a wire cut discharge work machine is connected to a wire electrode 1 through a conductive terminal, while a net wire 9 is connected to the vicinity of a work section part of a workpiece 2 by means of adsorptive contactors 21, 25. The contactor 21 is pressed and fixed to the workpiece 2 by means of a magnet 20a. In case the workpiece 2 is not a magnetic body, the contactor 25 is connected to the workpiece 2 by means of a sucker 24. Thus, not only length of a lead line 22 but also the inductance of the cable can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machining apparatus, and more particularly to a connection structure for a power supply cable that connects an electric discharge machining power supply and a plurality of workpieces.

Figure 1 shows the overall configuration of a conventional electrical discharge machining device, in which a wire electrode 1 fed out from a reel is connected to a workpiece 2.
The workpiece 2 is passed through the machining start hole, and the workpiece 2 is electrically discharge-machined into an arbitrary shape by supplying current. 3.4 is a current-carrying terminal that is connected to the wire electrode 1, a power supply manufactured by 4 manufacturers, and 5 a transistor, which is turned on and off by a switching command from a control circuit (not shown). 8 is a core wire of a coaxial cable that is wired as a current-carrying cable, and 9 is a mesh wire. The core wire 8 connects the current-carrying terminals 6 and 4 and the collector of the transistor 5. The mesh wire 9 is connected to the positive electrode of the processing power source 4 and is wired to the vicinity of the wire electrode 1. 6 and 7 are switches and capacitors connected in series between the collector of the transistor 5 and the positive electrode of the processing power source 4. Reference numeral 10 denotes a single wire cable, which connects the end of the mesh wire 8 which is wired to the vicinity of the current-carrying terminal 3.4 to the metal fitting 12 of the crank that fixes the workpiece 2 and the bolt of the workpiece mounting base 11. It is. In this way, the current-carrying cable includes the core wire 8 and the mesh wire 9 of the coaxial cable. It is composed of a single wire cable 10, and two parts, an upper current-carrying system and a lower current-carrying system, are connected between the workpiece 2'Ik.
It is divided into systems.

According to the same configuration, a pulse voltage is applied to the base of the transistor 5 in response to a switching command from a control circuit (not shown), and a current is supplied to the wire electrode through the current-carrying cable, thereby electrical discharge machining the workpiece. According to such a wiring structure, the characteristic impedance in the coaxial cable section is kept relatively low because the mutual inductance is reduced and the amount between each wire is increased. Since the single wire cable 10 is wired in a long length near the unprocessed layer, mutual inductance occurs between the single wire cable 10 and a nearby conductor, and the characteristic impedance becomes high. In other words, in the area where coaxial cable can be wired, there are core wires (output wires) and mesh wires (
Since the current direction of the regression line (regression line) is opposite, magnetic flux is generated due to each current change, and the magnetic flux does not go outside because the directions of the magnetic lines of force cancel each other out.

In the above-mentioned single-wire cable, the magnetic flux generated when the pulse current changes flows outside, and this magnetic flux couples with a nearby conductor, resulting in mutual inductance between the single-wire cable and the single-wire cable.

If electrical discharge machining is performed with such a high characteristic impedance, the rise and fall of the machining lightning will be delayed as shown in Figure 2, making it impossible to increase the discharge 5Fjt.
It had the disadvantage of low processing efficiency. In addition, the delay in the current waveform causes the machining interval of the workpiece to scatter, and energy is directed to melting that part rather than performing electrical discharge machining, leaving a melted and resolidified layer on the machining surface. . As a result, this layer becomes a deteriorated layer and must be manually scraped or subjected to electric discharge machining again, and must be performed with sufficient energy, which is caused by the delay in the rise and fall of the machining current. There were many problems.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to reduce the total characteristic impedance of an electric discharge machining pulse supply line and improve electric discharge machining efficiency.

In the present invention, one length of the coaxial or parallel cable that is routed close to the wire electrode is connected to the current-carrying terminal of the wire electrode, and the other 1M is connected to the terminal of the coaxial or parallel cable with a current-carrying contact that has an adsorption property to attach the current-carrying contact to the surface of the workpiece. The above object has been achieved by allowing contact connection at any position.

Hereinafter, specific examples thereof will be described in detail with reference to FIGS. 3 to 7. FIG. 3 shows an embodiment of the present invention, and the same reference numerals as in FIG. a@1 indicate the same parts. In this embodiment, the coaxial cable is wired close to the wire electrode, and its core 1s8 is connected to the current-carrying terminals 3 and 4, which is the same as the conventional structure, but the end of the mesh wire 9 has a short length. A lead wire 22 covered with an insulator 23 is attached to the end of the lead wire 22, and a magnet 2 is inserted into the center of the lead wire 22, as shown in FIGS. 4(a) and 4(b).
0m, 20b is the installation. This magnet is 20m long,
20b is attracted to a location close to the electrical discharge machining portion of the workpiece 2, and electrical connection is established by the contactor 21. As a result, the wiring distance using a single wire can be significantly shortened, and mutual inductance can be reduced. That is, the delay in the rise and fall of the electrical discharge machining current, which has been a problem in the past, is almost eliminated.

Note that the length of the lead wire 22 varies somewhat depending on the processing area of the workpiece 2, but a large number of lead wires of different lengths with clips attached to both ends are prepared, and the mesh wire 9 and the contact 21 are prepared in advance.
This request can be met by connecting it with a clip.

Further, there are cases where the workpiece 2 is not a magnetic material, and in that case, the purpose can be achieved by configuring the contact structure as shown in FIGS. 5 to 7.

Figures 5 and 6 use a pneumatic suction cup.
In the figure, a bent pin 25 made of a spring material is fixed inside the suction cup 24, and the pin 25 is electrically connected when the suction cup is suctioned to the workpiece 2. .

Further, in FIG. 6, in order to obtain an electrical connection, a metal wave 26 is filled inside the suction cup 24, and the lead edge 22 is connected to it. According to this, workpiece 2
The contact area is large and the reliability is high.

As is clear from the above-described embodiments, according to the present invention, the single-wire wiring portion of the coaxial or parallel cable for supplying electrical discharge machining pulses can be wired as short as possible, and the total characteristic impedance can be minimized. In other words, shortening the rise time υ and fall time of the electric discharge machining current can shorten the current pulse width, which in turn increases the number of pulses per fixed time and increases the electric discharge 5FIt, which enables high-precision machining and It can be said to be ideal as a processing device.

[Brief explanation of drawings]

Figure 1 is an overall configuration diagram of a conventional electric discharge machining device, a configuration diagram of main parts of an electric discharge machining device showing one embodiment, Figure 11g4 (a) is a plan view of a magnet that is an adsorption part, and Figure 4 (b) is a The cross-sectional view, FIG. 5, and FIG. 6 are cross-sectional views showing other actual examples of suction components showing other embodiments. DESCRIPTION OF SYMBOLS 1... Wire electrode, 2... Workpiece, 3, 4... Current-carrying terminal, 8... Coaxial cable core wire, 9... Coaxial cable network wire, 20a, 20b... Magnet, 21...・・・
Contactor, 22... Lead wire, 23... Insulation, 24...
...Suction cup, 25...pin, 26...metallic wave. Agent Patent Attorney Tadashi Akimoto Figure 1 0 Figure 2 Figure 3 Figure 5° Figure 6

Claims (1)

[Scope of Claims] 1. A wire-cut electric discharge machining apparatus for machining a workpiece by generating an electric discharge in a machining gap where a wire electrode and a workpiece face each other, the electric discharge machining power supply, the wire electrode, One wire of a power supply cable, which is a coaxial or parallel cable, is connected to the wire electrode side, and the other wire is connected to the end of the power supply cable, which is wired between the workpieces and has an adsorption property to the workpiece. A power supply cable in an electric discharge machining apparatus characterized in that the power supply cable is connected to a suction means provided with a current-carrying contact, and is configured such that the power supply cable can be connected to the vicinity of the machining part of the workpiece by means of the cough suction means. connection structure. 2. The connection structure for a power supply cable in an electric discharge machining apparatus according to claim 1, wherein the attraction means is a magnet having a contactor therein. 5. The connection structure for a power supply cable in an electric discharge machining apparatus according to claim 1, wherein the suction means is a suction cup having a contactor therein.