JPS61219518A - Machining energy feeding circuit for electric discharge machine - Google Patents

Abstract

PURPOSE:To carry out high speed machining with an electric discharge machine by increasing the length of a cable for moving an electrode and a workpiece and, further, forming a circuit in such a way that it suppresses increase in inductance, in a feeding cable for an electric discharge machine. CONSTITUTION:The inside and outside conductors at one end of a cable A are connected to each other, and one end of a cable C is connected to the other end of the cable A between their inside and outside conductors respectively, while a junction part between both outside conductors is connected to a work table T, and the inside conductor on the other end of the cable C is connected to a discharging electrode E. Further, its outside conductor is connected to one end of a cable D, the other end of which is connected to a part (f) of the work table T in the vicinity of a workpiece W. In the cable A, a magnetic flux due to a current is restricted within the cable, sharply reducing inductance. In the cable C, a magnetic flux of a return passage current is reduced due to the magnetic flux of a divided outgoing passage current, reducing inductance in accordance with the magnitude of the divided current. Inductance is negligible in the cable D.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application This invention relates to a circuit that supplies machining energy between an electrode and a workpiece from an energy supply power source of an electric discharge machine.

b. Conventional technology An electrical discharge machine requires a cable that supplies machining energy generated by a machining power source to two parts (an electrode and a liquid inlet provided in the machine body). This processing cable is required to have various characteristics depending on the processing purpose. For example, when high-speed machining is performed in a wire-knot electric discharge machine, the machining cable is required to have low inductance. As a method of reducing the inductance of the cable for processing, for example, a shielded wire (J: A in FIG. 2) is used.

In this example, the a @ terminal of the left-most internal conductor of shielded wire A is connected to the θ pole of the power supply, the b terminal of the external conductor is connected to the O pole, and the C terminal of the right-most internal conductor is connected to single-core cable B. , the d terminal of the outer conductor is connected to the worktable T. The right end of the cable B is connected to a discharge electrode F, a workpiece W is placed on a workbench T, and electrical discharge machining is performed between the workpiece W and the discharge electrode E. When processing is performed, the current changes from b to cable A (
The flow is as follows: external conductor)→d→workbench T→workpiece W→electrode E→cable β→C→cable A (internal conductor)→a. At this time, current flows in opposite directions in the outgoing and returning paths in cable 8, and the generated magnetic flux is canceled out, reducing the inductance of this portion. Although the size of the cape/L and 17) structural stage is 1 to 1 different in length, it is only a fraction of that of a single-core cable.

C0 Problems to be Solved by the Invention However, in the conventional method, the portion of cable B in Figure 2 does not have the effect of canceling the magnetic flux like cable A, so as this portion becomes longer4, the inductance increases. I will do it. Since an electric discharge machine performs machining by relative movement between the electrode and the workpiece, it is necessary to make cable B long in order to allow the electrode and workpiece to move freely. , an increase in inductance could not be avoided.

This invention was made with attention to these points,
The purpose is to provide a machining energy supply circuit that uses conventional technology to lengthen the cable C section in Figure 1 (cable B section in Figure 2) and suppresses the increase in inductance. be.

Means for Solving the d0 Problem In order to achieve the above object, the present invention provides an inner and outer conductor at one end of the cable A consisting of concentric mutually insulated inner and outer conductors at both poles of the processing energy supply power source. Connect the outer conductors to each other, and connect one end of a cable C having the same structure to the other end of the cable A using the inner and outer conductors, and connect the connection parts of the inner and outer conductors to the workpiece. Connect the internal conductor of the other end of the cable C to a workbench with good conductivity on which the cable D is placed, and connect the internal conductor of the other end of the cable C to the discharge electrode.
The cable D is connected to one end of the cable D, and the other end of the cable D is connected to a location on the workbench near the workpiece.

03 Operation The operation of this invention will be explained with reference to FIG. When machining is carried out, current flows from the Φ side of the machining energy supply power source to terminal 31 of the leftmost external conductor of cable A, along the arrow, and to the rightmost terminal d.
It is divided into two parts. One of them flows from the left end of cable C through the outer conductor to the right end, and at this point, cable D
The liquid flows from point f of the workbench T through the workbench T with low resistance as shown by the arrow, and reaches the liquid □ workpiece W. The other one flows into the workbench 1 from the □ terminal d as shown by the arrow and reaches the workpiece W. The current that has reached the workpiece is discharged between the electrodes E, flows from the electrode E through the internal conductor of the cable C as shown by the arrow, passes through the internal conductor from the leftmost terminal C to the cable, and then passes through the leftmost terminal A. Flows from □ to the θ゛ side of the power supply.

In cable A, the currents are of equal magnitude and opposite in direction, so the magnetic flux due to the current is confined within the cable, significantly reducing the inductance. In cable C, the magnetic flux due to the forward shunt current reduces the magnetic flux due to the backward current, and the inductance decreases in accordance with the magnitude of the shunted current.

Since there is no reciprocating current in cable D, it has an inductance corresponding to the diameter and length of the core wire, but since d and f are connected by a conductor with low resistance, the inductance can be ignored. Therefore, in this circuit, the inductance is reduced compared to the conventional circuit due to the shunt current in the cable C section.

f. Example Next, an example of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of an embodiment in which the present invention is applied to a wire-cut electrical discharge machine. Cable A uses a shielded wire, and cable C also uses a similar shielded wire. An actual cable is used by bundling several to several dozen shielded wires with such a configuration. Further, the cables A and C are not limited to shielded wires, but may be of any structure as long as the magnetic fluxes generated by the currents on the outward and return paths cancel each other out.

The left ends of the inner and outer conductors of cable A are connected to the OO side of the power supply, and the right ends are connected to the left ends of the inner and outer conductors of cable C,
The connection point d of the external conductor is connected to the worktable T with low inductance and resistance.

The right end of the inner conductor of the cable C is connected to the electrode terminal e, and the right end of the outer conductor is connected to a point f on the workbench T near the workpiece W through the single-core cable D. Regarding the operation of this circuit, as described above, cable 8 has a small inductance as before, and cable C has a reduced inductance M due to the shunt current on the outward path. cable]
] Since the inductance and resistance between d and f of the workbench are small, the inductance of (horn pull C, I') and d,
(parallel circuit between f) This can be ignored. Therefore, the circuit as a whole has less reductance than the conventional circuit.

g6 Effects of the Invention As can be seen from the above explanation, this invention has the configuration described in the claims, so the couple C portion (see Fig. 1) is made long and the inductance is small. It is possible to provide an energy supply circuit.

[Brief explanation of drawings]

FIG. 1 is a detailed explanatory diagram of the present invention, and FIG. 2 is an explanatory diagram of a conventional machining energy supply circuit. A... Shield wire (cable consisting of inner and outer conductors) B
... Single-core cable C ... Shield wire (cable consisting of inner and outer conductors) D
・・・Single core cable

Claims (1)

[Claims] Connect the inner and outer conductors of one end of a cable A consisting of concentric, mutually insulated inner and outer conductors to both poles of the processing energy supply power source, and connect a cable with the same structure to the other end of the cable A. Connect one end of cable C to the inner and outer conductors, connect the connecting parts of both outer conductors to a good conductor workbench on which the workpiece is placed, and discharge the inner conductor at the other end of cable C. A machining energy supply circuit for an electrical discharge machine, which is connected to an electrode, an external conductor is connected to one end of a cable D, and the other end of the cable D is connected to a location on the workbench close to a workpiece.