WIRE ELECTRICAL DISCHARGE MACHINING APPARATUS

• US 20100084378A1
• Filed: 10/24/2006
• Published: 04/08/2010
• Est. Priority Date: 10/24/2006
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Hashimoto, Takashi, Ukai, Yoshikazu, Hattori, Koichiro, Yamada, Hisashi, Onodera, Yasuo, Sato, Tatsushi
• Granted Patent: US 8,003,911 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 7/04 Apparatus for supplying current to working gap; Electric circuits specially adapted therefor

Abstract

A machining-energy calculating unit accumulates a discharge current value for each discharge position to calculate a machining energy in a certain time period from the present time to the past time. An energy-distribution changing unit determines the presence or absence of imbalance in the energy by obtaining a machining energy distribution in an up-down direction of the machining gap based on the machining energy, and when there is imbalance, the energy-distribution changing unit produces a new open/close pattern in which a machining energy distribution that eliminates the imbalance. Power feeding is then performed based on the new open/close pattern.

Claims

1. A wire electrical discharge machining apparatus, when comprising an upper-side path that passes through an upper-side feeding point on which a wire electrode is slidable on an upper side of a workpiece and a lower-side path that passes through a lower-side feeding point on which the wire electrode is slidable on a lower side of the workpiece as feeding paths for supplying a discharge current from a machining power supply to an inter-electrode gap that is a machining gap between the wire electrode and the workpiece, the wire electrical discharge machining apparatus comprising:

an upper-side-path open/close unit and a lower-side-path open/close unit capable of separately opening and closing the upper-side path and the lower-side path;

an open/close pattern setting unit that performs power feeding in a manner in which a one-side feeding system using either one of the upper-side path and the lower-side path and an upper-and-lower-both-side feeding system simultaneously using both of the upper-side path and the lower-side path are mixed, and sets an open/close pattern for controlling opening and closing of the upper-side-path open/close unit and the lower-side-path open/close unit separately or simultaneously, as an instruction for realizing a desired feeding mode in each of the one-side feeding system and the upper-and-lower-both-side feeding system;

a discharge position detecting unit that detects a discharge position based on any of a sub discharge current value and a main discharge current value supplied from the upper-side feeding point and the lower-side feeding point to the inter-electrode gap;

a machining energy calculating unit that calculates a machining energy at a present position of the wire electrode based on the main discharge current value for every discharge position that is detected by the discharge position detecting unit in a certain period from a present time to a past time;

a machining-energy-distribution changing unit that, when there is imbalance in machining energy distribution in an up-down direction of the machining gap obtained based on the machining energy calculated by the machining energy calculating unit, generates a new open/close pattern in which the machining energy distribution is changed to obtain a predetermined machining energy distribution for eliminating the imbalance; and

a driving unit that, upon receiving the new open/close pattern from the machining energy distribution changing unit, performs an open/close control of the upper-side-path open/close unit and the lower-side-path open/close unit, which is to be performed in accordance with an open/close pattern from the open/close pattern setting unit, in accordance with the new open/close pattern.

2. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit, when there is imbalance in the machining energy, generates the new open/close pattern in which the machining energy distribution is changed to reduce a machining energy difference between an upper end side and a lower end side of the machining gap.

3. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit, when there is imbalance in the machining energy, generates the new open/close pattern in which the machining energy calculated by the machining energy calculating unit is changed to be close to a preset appropriate machining energy.

4. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes a feeding pattern changing unit that changes the open/close pattern set by the open/close pattern setting unit to the new open/close pattern in which a ratio between number of power feedings from the upper-side path and number of power feedings from the lower-side path is made different, depending upon a magnitude of present imbalance in the machining energy.

5. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes a feeding pattern changing unit that changes the open/close pattern set by the open/close pattern changing unit to the new open/close pattern in which a ratio of number of power feedings is made different between the two one-side feedings and the upper-and-lower-both-side feeding, depending upon a magnitude of the machining energy calculated by the machining energy calculating unit.

6. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes a feeding-pulse-energy changing unit that changes the open/close pattern set by the open/close pattern setting unit to the new open/close pattern in which a feeding pulse energy per feeding pulse is made different between at a time of power feeding using the upper-side path and at a time of power feeding using the lower-side path to cause the machining energy calculated by the machining energy calculating unit to be close to a preset appropriate machining energy, depending upon a magnitude of present imbalance of the machining energy.

7. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes a feeding-pulse-energy changing unit that changes the open/close pattern set by the open/close pattern setting unit to the new open/close pattern in which a feeding pulse energy per feeding pulse is made different between the two one-side feedings and the upper-and-lower-both-side feeding, depending upon a magnitude of the machining energy calculated by the machining energy calculating unit.

8. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes a reference-machining-energy setting unit that sets a reference machining energy that provided a target value for the machining energy to be calculated by the machining energy calculating unit, and generates the new open/close pattern in which the machining energy distribution is changed to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.

9. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes a reference-machining-energy setting unit that sets a reference machining energy that provides a target value for the machining energy to be calculated by the machining energy calculating unit and provides a machining energy value that is different between an upper end side and a lower end side of the machining gap, and generates the new open/close pattern in which the machining energy distribution is changed to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.

10. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes

a reference-machining-energy setting unit that sets a reference machining energy that provides a target value for the machining energy to be calculated by the machining energy calculating unit;

and

a feeding pattern changing unit that changes the open/close pattern set by the open/close pattern setting unit to the new open/close pattern in which a ratio of number of power feedings is made different between the two one-side feedings and the upper-and-lower-both-side feeding to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.

11. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes

a reference-machining-energy setting unit that sets a reference machining energy that provides a target value for the machining energy to be calculated by the machining energy calculating unit and provides a machining energy value that is different between an upper end side and a lower end side of the machining gap;

and

a feeding pattern changing unit that changes the open/close pattern set by the open/close pattern setting unit to the new open/close pattern in which a ratio of number of power feedings is made different between the two one-side feedings and the upper-and-lower-both-side feeding to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.

12. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes

a reference-machining-energy setting unit that sets a reference machining energy that provides a target value for the machining energy to be calculated by the machining energy calculating unit;

and

a feeding pulse energy changing unit that changes the open/close pattern set by the open/close pattern setting unit to the open/close pattern in which a feeding pulse energy per feeding pulse is made different between at a time of power feeding using the upper-side path and at a time of power feeding using the lower-side path to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.

13. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes

a reference-machining-energy setting unit that sets a reference machining energy that provides a target value for the machining energy to be calculated by the machining energy calculating unit and provides a machining energy value that is different between an upper end side and a lower end side of the machining gap;

and

a feeding pulse energy changing unit that changes the open/close pattern set by the open/close pattern setting unit to the open/close pattern in which a feeding pulse energy per feeding pulse is made different between at a time of power feeding using the upper-side path and at a time of power feeding using the lower-side path to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.

14. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes

a reference-machining-energy setting unit that sets a reference machining energy that provides a target value for the machining energy to be calculated by the machining energy calculating unit;

and

a feeding pulse energy changing unit that changes the open/close pattern set by the open/close pattern setting unit to the open/close pattern in which a feeding pulse energy per feeding pulse is made different between at a time of power feeding using the two one-sides and at a time of power feeding using the upper-and-lower-both-side to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.

15. The wire electrical discharge machining apparatus according to claim 1, wherein the machining-energy-distribution changing unit includes

a reference-machining-energy setting unit that sets a reference machining energy that provides a target value for the machining energy to be calculated by the machining energy calculating unit and provides a machining energy value that is different between an upper end side and a lower end side of the machining gap;

and

a feeding pulse energy changing unit that changes the open/close pattern set by the open/close pattern setting unit to the open/close pattern in which a feeding pulse energy per feeding pulse is made different between at a time of power feeding using the two one-sides and at a time of power feeding using the upper-and-lower-both-side to reduce a difference between the machining energy calculated by the machining energy calculating unit and the reference machining energy.