WIRE ELECTRIC DISCHARGE MACHINE

• US 20090314747A1
• Filed: 10/24/2006
• Published: 12/24/2009
• Est. Priority Date: 10/24/2006
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Hashimoto, Takashi, Hattori, Koichiro, Yamada, Hisashi, Onodera, Yasuo, Sato, Tatsushi
• Granted Patent: US 8,093,526 B2
• Time in Patent Office: Days
• US Class Current: 219/69.130
• CPC Class Codes: B23H 1/022 for shaping the discharge pulse train B23H1/024 takes precedence
• CPC Class Codes: B23H 2300/20 Relaxation circuit power supplies for supplying the machining current, e.g. capacitor or inductance energy storage circuits
• CPC Class Codes: B23H 7/04 Apparatus for supplying current to working gap; Electric circuits specially adapted therefor
• CPC Class Codes: B23H 7/14 Electric circuits specially adapted therefor, e.g. power supply B23H3/02 takes precedence

Abstract

A wire electric discharge machine includes a wire electrode; a machining power supply that supplies a machining current to between the wire electrode and a workpiece; a first power feed contact and a second power feed contact that respectively feed power to the wire electrode; a first machining-current loop that lets a first machining current to flow from the first power feed contact toward the workpiece; a second machining-current loop that lets a second machining current to flow from the second power feed contact toward the workpiece; an impedance switching circuit that is provided in at least any one of the first machining-current loop and the second machining-current loop; and a control unit that controls a flow ratio of the first machining current and the second machining current by changing an impedance of the impedance switching circuit.

Claims

1-10. -10. (canceled)

11. A wire electric discharge machine that generates an electric discharge between a wire electrode and a workpiece by application of a voltage thereby machining the workpiece, the wire electric discharge machine comprising:

a wire electrode that is capable of moving;

a machining power supply that supplies a machining current to between the wire electrode and a workpiece;

a power feed contact including a first power feed contact and a second power feed contact that respectively feed power by having contact with the wire electrode at least two points opposed to each other across the workpiece;

a first machining-current loop that includes the machining power supply, the first power feed contact, the wire electrode, and the workpiece, and lets a first machining current to flow from the first power feed contact toward the workpiece;

a second machining-current loop that includes the machining power supply, the second power feed contact, the wire electrode, and the workpiece, and lets a second machining current to flow from the second power feed contact toward the workpiece;

an impedance switching circuit that is provided in at least any one of the first machining-current loop and the second machining-current loop, the impedance switching circuit having a variable impedance; and

a control unit that controls a flow ratio of the first machining current and the second machining current by changing the impedance of the impedance switching circuit.

12. The wire electric discharge machine according to claim 11, wherein

the impedance switching circuit includes a first impedance switching circuit and a second impedance switching circuit,

the first impedance switching circuit is provided between the first power feed contact and the machining power supply in the first machining-current loop,

the second impedance switching circuit is provided between the second power feed contact and the machining power supply in the second machining-current loop, and

the control unit controls the flow ratio of the first machining current and the second working current by changing impedances of the first impedance switching circuit and the second impedance switching circuit.

13. The wire electric discharge machine according to claim 11, wherein the impedance switching circuit is arranged between the power feed contact and the machining power supply.

14. The wire electric discharge machine according to claim 11, wherein the impedance switching circuit includes

a plurality of reactors;

and

a switch for switching connections to the reactors.

15. The wire electric discharge machine according to claim 11, wherein the impedance switching circuit includes

a plurality of resistor elements;

and

a switch for switching connections to the resistor elements.

16. The wire electric discharge machine according to claim 11, wherein

the machining power supply includes

a sub machining power supply that applies a low voltage so as to supply a discharge current pulse to between the wire electrode and the workpiece for a purpose of detecting an interelectrode state;

and

a main machining power supply that applies a voltage higher than that is applied by the sub machining power supply so as to supply the machining current to between the wire electrode and the workpiece, and

any of the sub machining power supply and the main machining power supply is selectively used as the machining power supply.

17. The wire electric discharge machine according to claim 11, wherein the control unit controls the impedance based on at least any one of a magnitude of the machining current, a shape of the workpiece, a type of the wire electrode, a type of a machining fluid, and a vibrational state of the wire electrode.

18. The wire electric discharge machine according to claim 11, wherein the impedance switching circuit is integrated with the machining power supply.

19. The wire electric discharge machine according to claim 11, wherein the impedance switching circuit is arranged near the power feed contact.

20. A wire electric discharge machine that generates an electric discharge between a wire electrode and a workpiece by application of a voltage thereby machining the workpiece, the wire electric discharge machine comprising:

a wire electrode that runs is capable of moving;

a machining power supply including a first machining power supply and a second machining power supply that respectively supply a machining current to between the wire electrode and a workpiece;

a power feed contact including a first power feed contact and a second power feed contact that respectively feed power by having contact with the wire electrode at least two points opposed to each other across the workpiece;

a first machining-current loop that includes the first machining power supply, the first power feed contact, the wire electrode, and the workpiece, and lets a first machining current to flow from the first power feed contact toward the workpiece;

a second machining-current loop that includes the first machining power supply, the second power feed contact, the wire electrode, and the workpiece, and lets a second machining current to flow from the second power feed contact toward the workpiece;

a third machining-current loop that includes the second machining power supply, the first power feed contact, the wire electrode, and the workpiece, and lets a third machining current to flow from the first power feed contact toward the workpiece;

a fourth machining-current loop that includes the second machining power supply, the second power feed contact, the wire electrode, and the workpiece, and lets a fourth machining current to flow from the second power feed contact toward the workpiece;

an impedance switching circuit that is provided in at least any one of the first machining-current loop and the second machining-current loop and at least any one of the third machining-current loop and the fourth machining-current loop so as to be shared among at least two machining-current loops, the impedance switching circuit having a variable impedance; and

a control unit that controls a flow ratio of the first machining current and the second machining current and a flow ratio of the third machining current and the fourth machining current by changing the impedance of the impedance switching circuit.

21. The wire electric discharge machine according to claim 20, wherein the impedance switching circuit is arranged between the power feed contact and the machining power supply.

22. The wire electric discharge machine according to claim 20, wherein the impedance switching circuit includes

a plurality of reactors;

and

a switch for switching connections to the reactors.

23. The wire electric discharge machine according to claim 20, wherein the impedance switching circuit includes

a plurality of resistor elements;

and

a switch for switching connections to the resistor elements.

24. The wire electric discharge machine according to claim 20, wherein

the machining power supply includes

a sub machining power supply that applies a low voltage so as to supply a discharge current pulse to between the wire electrode and the workpiece for a purpose of detecting an interelectrode state;

and

a main machining power supply that applies a voltage higher than that is applied by the sub machining power supply so as to supply the machining current to between the wire electrode and the workpiece, and

any of the sub machining power supply and the main machining power supply is selectively used as the machining power supply.

25. The wire electric discharge machine according to claim 20, wherein the control unit controls the impedance based on at least any one of a magnitude of the machining current, a shape of the workpiece, a type of the wire electrode, a type of a machining fluid, and a vibrational state of the wire electrode.

26. The wire electric discharge machine according to claim 20, wherein the impedance switching circuit is integrated with the machining power supply.

27. The wire electric discharge machine according to claim 20, wherein the impedance switching circuit is arranged near the power feed contact.