WIRE ELECTRICAL DISCHARGE MACHINING APPARATUS, MACHINING CONTROL DEVICE, AND MACHINING CONTROL PROGRAM

• US 20150290733A1
• Filed: 10/30/2012
• Published: 10/15/2015
• Est. Priority Date: 10/30/2012
• Status: Abandoned Application

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Nakagawa, Takayuki
• Application Number:
  US14/439,349
• Publication Number:
  US 20150290733A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23H 7/104 Wire tension control
• CPC Class Codes: B23H 7/14 Electric circuits specially adapted therefor, e.g. power supply B23H3/02 takes precedence
• CPC Class Codes: B23H 7/20 for programme-control, e.g. adaptive programme-control systems in general G05B19/00

Abstract

The wire electrical discharge machining apparatus includes: a tension control motor controlling tension and feed speed of the wire extending under tension between a tension control roller and a winding roller by controlling the tension control motor; an external force estimator calculating an external force estimate applied to the tension control motor; an external force determiner determining, based on the external force estimate, whether there is a sign indicative of breaking of the wire; a machining power control device controlling a machining power source to reduce electrical discharge machining energy between the wire and a workpiece when determining that there is a sign indicative of breaking of the wire; a motor position detector detecting a rotational position of the tension control motor; and a motor control device controlling the tension control motor on the basis of the rotational position such that the feed speed stays within a predetermined range.

Claims

1. A wire electrical discharge machining apparatus, comprising:

a machining power source that applies a voltage between a wire and a workpiece;

a wire feed roller that is arranged on a side from which the wire is fed and feeds the wire;

a winding roller that is arranged on a side to which the wire is collected and winds the wire at a constant speed;

a tension control motor that controls a tension and a feed speed of the wire extending under tension between the wire feed roller and the winding roller by controlling the wire feed roller;

an external force estimator that calculates an estimated value of an external force applied to the tension control motor as an external force estimate;

a determining unit that determines, on a basis of the external force estimate, whether there is a sign indicative of breaking of the wire;

a power control device that, when it is determined that there is a sign indicative of breaking of the wire, controls the machining power source such that electrical discharge machining energy that the machining power source is to apply between the wire and the workpiece is reduced;

a motor position detector that detects a rotational position of the tension control motor; and

a motor control device that controls the tension control motor on a basis of the rotational position such that a feed speed of the wire stays within a predetermined range, wherein

the rotational position of the tension control motor detected by the motor position detector and a current detection signal detected with respect to current supplied to the tension control motor by the motor control device are input to the external force estimator as information on an operation of the wire feed roller, and

the external force estimator calculates the external force estimate by using the rotational position and the current detection signal that have been input.

2. The wire electrical discharge machining apparatus according to claim 1, wherein the determining unit determines, on a basis of a transition of the external force estimate, whether there is a sign indicative of breaking of the wire.

4. The wire electrical discharge machining apparatus according to claim 1, further comprising a display unit that displays information indicating that there is a sign indicative of breaking of the wire when it is determined that there is a sign indicative of breaking of the wire.

3. (canceled)

5. A machining control device, comprising:

a control unit that controls a tension and a feed speed of a wire extending under tension between a wire feed roller and a winding roller by controlling the wire feed roller, the wire feed roller being arranged on a side from which the wire is fed and feeding the wire and the winding roller being arranged on a side to which the wire is collected and winding the wire at a constant speed;

an external force estimator that calculates an estimated value of an external force applied to the tension control motor as an external force estimate in accordance with a magnitude of the tension;

a determining unit that determines, on a basis of the external force estimate, whether there is a sign indicative of breaking of the wire; and

a power control device that, when it is determined that there is a sign indicative of breaking of the wire, controls a machining power source such that electrical discharge machining energy to be applied between the wire and the workpiece is reduced, wherein

the control unit controls a tension and a feed speed of the wire by controlling the tension control motor on a basis of a rotational position of the tension control motor that provides a tension and a feed speed to the wire such that a change in a feed speed of the wire stays within a predetermined range,

the rotational position and a current detection signal detected with respect to current supplied to the tension control motor by the control unit are input to the external force estimator as information on an operation of the wire feed roller, and

the external force estimator calculates the external force estimate by using the rotational position and the current detection signal that have been input.

6. A machining control program that causes a computer to execute;

a wire controlling step of controlling a tension and a feed speed of a wire by controlling a tension control motor on a basis of a rotational position of the tension control motor that provides a tension and a feed speed to the wire such that a feed speed of the wire stays within a predetermined range, the wire extending under tension between a wire feed roller and a winding roller, the wire feed roller being arranged on a side from which the wire is fed and feeding the wire, and the winding roller being arranged on a side to which the wire is collected and winding the wire at a constant speed;

an external force calculating step of, when the rotational position and a current detection signal detected with respect to current supplied to the tension control motor are input as information on an operation of the wire feed roller, calculating an estimated value of an external force applied to the tension control motor as an external force estimate by using the rotational position and the current detection signal that have been input;

a determining step of determining whether there is a sign indicative of breaking of the wire on a basis of the external force estimate; and

a power controlling step of, when it is determined that there is a sign indicative of breaking of the wire, controlling a machining power source such that electrical discharge machining energy to be applied between the wire and the workpiece is reduced.