Contact detection apparatus for wire electrical discharge machine with capability to vary applied gap voltage

Patent metadata

Field	Value
Publication number	US-9314859-B2
Application number	US-201313780813-A
Country	US
Kind code	B2
Filing date	Feb 28, 2013
Priority date	Apr 24, 2012
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A contact detection apparatus for a wire electrical discharge machine includes a voltage application unit adapted to apply a detection voltage to detect contact between a wire electrode and a workpiece; a contact determination unit adapted to determine contact or non-contact between the wire electrode and the workpiece based on changes in the detection voltage applied by the voltage application unit; and a voltage value changing unit adapted to change a voltage value of the detection voltage applied by the voltage application unit.

First claim

What is claimed is:

1. A contact detection apparatus for a wire electrical discharge machine, said apparatus comprising:
a voltage application unit configured to apply a detection voltage to detect contact between a wire electrode and a workpiece during non-machining periods;
a contact determination unit configured to determine contact or non-contact between the wire electrode and the workpiece based on changes in the detection voltage applied by the voltage application unit; and
a controller configured to change, during the non-machining periods, a voltage value of the detection voltage applied by the voltage application unit according to a property of the workpiece.

2. The contact detection apparatus according to claim 1 , wherein
the voltage application unit comprises voltage sources, resistors, and switching units coupled to the voltage sources and resistors, and
the controller is configured to change the voltage value by switching over the voltage sources and/or the resistors using the switching units.

3. The contact detection apparatus according to claim 1 , wherein the voltage application unit comprises a variable-voltage source.

4. The contact detection apparatus according to claim 1 , wherein the property of the workpiece comprises a roughness of a surface of the workpiece to be contacted with the wire electrode.

5. The contact detection apparatus according to claim 1 , wherein
the detection voltage has a first voltage value corresponding to a first roughness of a surface of the workpiece to be contacted with the wire electrode, and a second voltage value corresponding to a second roughness of the surface,
the first voltage value is higher than the second voltage value, and
the first roughness is higher than the second roughness.

6. A contact detection apparatus for a wire electrical discharge machine, said apparatus comprising:
a voltage application unit configured to apply a detection voltage to detect contact between a wire electrode and a workpiece during non-machining periods;
a contact determination unit configured to determine contact or non-contact between the wire electrode and the workpiece based on changes in the detection voltage applied by the voltage application unit; and
a controller configured
to change, during the non-machining periods, a voltage value of the detection voltage applied by the voltage application unit;
to store a data table containing voltage values of the detection voltage in association with materials of the workpiece; and
to determine the voltage value of the detection voltage based on the data table as well as on the material of the workpiece set as a machining condition.

7. The contact detection apparatus according to claim 6 , wherein the voltage application unit comprises a variable-voltage source.

8. The contact detection apparatus according to claim 6 , wherein
the voltage application unit comprises voltage sources, resistors, and switching units coupled to the voltage sources and resistors, and
the controller is configured to change the voltage value by switching over the voltage sources and/or the resistors using the switching units.

9. A contact detection apparatus for a wire electrical discharge machine, said apparatus comprising:
a voltage application unit configured to apply a detection voltage to detect contact between a wire electrode and a workpiece during non-machining periods;
a contact determination unit configured to determine contact or non-contact between the wire electrode and the workpiece based on changes in the detection voltage applied by the voltage application unit;
a controller configured
to change, during the non-machining periods, a voltage value of the detection voltage applied by the voltage application unit;
to store a data table containing voltage values of the detection voltage in association with materials and sizes of the wire electrode; and
to determine the voltage value of the detection voltage based on the data table as well as on the material and size of the wire electrode set as machining conditions.

10. The contact detection apparatus according to claim 9 , wherein
the voltage application unit comprises voltage sources, resistors, and switching units coupled to the voltage sources and resistors, and
the controller is configured to change the voltage value by switching over the voltage sources and/or the resistors using the switching units.

11. The contact detection apparatus according to claim 9 , wherein the voltage application unit comprises a variable-voltage source.

Assignees

• Fanuc Corp

Inventors

• Matsunaga Tomoaki
• Takayama Yushi
• Kawahara Akiyoshi

Classifications

• B23H7/04 Primary

  Apparatus for supplying current to working gap; Electric circuits specially adapted therefor · CPC title

• B23H1/02 Primary

  Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges · CPC title

• B23H7/18

  for maintaining or controlling the desired spacing between electrode and workpiece · CPC title

• B23H2500/20

  Methods or devices for detecting wire or workpiece position · CPC title