WIRE ELECTRIC DISCHARGE MACHINE PERFORMING DISTORTION REMOVING MACHINING

• US 20130206731A1
• Filed: 11/29/2012
• Published: 08/15/2013
• Est. Priority Date: 02/15/2012
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: TAKAHASHI, Shouji
• Granted Patent: US 9,199,325 B2
• Time in Patent Office: Days
• US Class Current: 219/69.12
• CPC Class Codes: B23H 1/02 Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges
• CPC Class Codes: B23H 2600/12 Switching from rough cutting to finish machining
• CPC Class Codes: B23H 7/065 Electric circuits specially adapted therefor
• CPC Class Codes: B23H 7/20 for programme-control, e.g. adaptive programme-control systems in general G05B19/00

Abstract

When contact between a wire electrode and a workpiece is detected while, after wire electric discharge machining is ended, the wire electrode is moved (retraced) in the direction opposite to the machining direction along the machining path, the movement of the wire electrode is stopped. The wire electrode is moved in the offset direction from the contact position. When the wire electrode and the workpiece are brought into a non-contact state, the non-contact state is detected, and the movement of the wire electrode is stopped. The wire electrode is returned from the non-contact position to the machining path, and the wire electrode is retraced along the machining path in the state where the detection of contact between the wire electrode and the workpiece is neglected. Then, an amount of distortion of the workpiece is calculated from the contact position and the non-contact position.

Claims

1. A wire electric discharge machine performing distortion removing machining and configured to machine a workpiece by moving a wire electrode supported by upper and lower wire guides, and the workpiece relatively to each other, the wire electric discharge machine comprising:

an axial movement control portion which is configured, after the machining is ended, to move, relatively to the workpiece, the wire electrode from the machining end position to the machining start position along the machining path in the direction opposite to the machining direction;

a contact detection portion which is configured to detect contact between the wire electrode and the workpiece at the time when the wire electrode is moved relatively to the workpiece in the direction opposite to the machining direction;

a contact position storage portion which is configured, when the contact between the wire electrode and the workpiece is detected by the contact detection portion, to stop the relative movement of the wire electrode, so as to store, as a contact position, the position of the wire electrode with respect to the workpiece at the time of detection of the contact;

a non-contact position storage portion which is configured, after the contact position of the wire electrode is stored, to move the wire electrode in the offset direction relatively to the workpiece, and is configured, when the wire electrode and the workpiece are brought into a non-contact state, to detect the non-contact state, and to stop the relative movement of the wire electrode, so as to store, as a non-contact position, the position of the wire electrode with respect to the workpiece at the time of detection of the non-contact state;

a machining path return control portion which is configured to move, relatively to the workpiece, the wire electrode in the direction opposite to the offset direction from the non-contact position, and is configured to move, relatively to the workpiece, the wire electrode in the direction opposite to the machining direction along the machining path by a predetermined distance while neglecting the detection of contact between the wire electrode and the workpiece by the contact detection portion;

a distortion amount calculation portion which is configured to calculate an amount of distortion of the workpiece from the contact position stored in the contact position storage portion, and the non-contact position stored in the non-contact position storage portion; and

a distortion removing machining execution portion which is configured to perform distortion removing machining at the time when a maximum value of the amounts of distortion calculated by the distortion amount calculation portion is larger than a value set beforehand.

2. The wire electric discharge machine performing the distortion removing machining according to claim 1, further comprising a speed changing portion which can arbitrarily change the feed speed of the wire electrode at the time when the wire electrode is moved, relatively to the workpiece, from the machining end position to the machining start position along the machining path in the direction opposite to the machining direction.

3. The wire electric discharge machine performing the distortion removing machining according to claim 1, further comprising a stopping portion which stops the wire electrode at every predetermined distance at the time when the wire electrode is moved, relatively to the workpiece, from the machining end position to the machining start position along the machining path in the direction opposite to the machining direction.

4. The wire electric discharge machine performing the distortion removing machining according to claim 1, further comprising a moving portion which moves the wire electrode to the machining start position in the case where, when the wire electrode is moved in the offset direction relatively to the workpiece, the contact between the wire electrode and the workpiece cannot be released.

5. The wire electric discharge machine performing the distortion removing machining according to claim 1, further comprising a moving portion which, in machining a plurality of components successively from the workpiece, moves the wire electrode to the machining start position of a component to be machined subsequently to the currently machined component in the case where the contact between the wire electrode and the workpiece cannot be released at the time when the wire electrode is moved in the offset direction relatively to the workpiece.