Wire electric discharge machine capable of starting machining from short-circuit state
First Claim
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1. A wire electric discharge machine, comprising:
- a discharge inducing circuit including a first DC power supply connected to a machining gap between a wire electrode and workpiece via a first switching element and a current limiting resistance;
a current supply circuit including a second DC power supply connected to the machining gap via a second switching element;
a voltage detection circuit that detects a voltage of the machining gap;
a short-circuit detection circuit that detects a short-circuit state between the wire electrode and the workpiece based on the voltage detected by the voltage detection circuit; and
a control circuit that controls on and off of the first switching element and the second switching element, whereinthe control circuit is configured to supply a first current to process the workpiece, and a second current until a predetermined state is reached after starting machining,the second current being (i) smaller than the first current, (ii) insufficient to fuse the wire electrode even in a short-circuit state with the workpiece, but (iii) sufficient to form a discharge arc between the wire electrode and the workpiece, andthe first current and the second current are discrete and separated from each other.
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Abstract
Even if a machining gap between a wire electrode and workpiece is in a short-circuit state at a start of machining by a wire electric discharge machine, a high-frequency voltage in a pulse shape is applied and a small current is supplied to an extent that the wire electrode is not fused only in an initial fixed time at the start of machining. Then, the short circuit is released, though instantaneously, and a discharge occurs in that instant and the short circuit state is eliminated by discharge repulsion thereof and therefore, machining can be started.
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Citations
8 Claims
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1. A wire electric discharge machine, comprising:
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a discharge inducing circuit including a first DC power supply connected to a machining gap between a wire electrode and workpiece via a first switching element and a current limiting resistance; a current supply circuit including a second DC power supply connected to the machining gap via a second switching element; a voltage detection circuit that detects a voltage of the machining gap; a short-circuit detection circuit that detects a short-circuit state between the wire electrode and the workpiece based on the voltage detected by the voltage detection circuit; and a control circuit that controls on and off of the first switching element and the second switching element, wherein the control circuit is configured to supply a first current to process the workpiece, and a second current until a predetermined state is reached after starting machining, the second current being (i) smaller than the first current, (ii) insufficient to fuse the wire electrode even in a short-circuit state with the workpiece, but (iii) sufficient to form a discharge arc between the wire electrode and the workpiece, and the first current and the second current are discrete and separated from each other. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A wire electric discharge machine, comprising:
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a discharge inducing circuit including a first DC power supply connected to a machining gap between a wire electrode and workpiece via a first switching element and a current limiting resistance; a current supply circuit including a second DC power supply connected to the machining gap via a second switching element; a voltage detection circuit that detects a voltage of the machining gap; a short-circuit detection circuit that detects a short-circuit state between the wire electrode and the workpiece based on the voltage detected by the voltage detection circuit; and a control circuit that controls on and off of the first switching element and the second switching element, wherein the control circuit is configured to supply a first current to process the workpiece, and a second current until a predetermined state is reached when the short circuit is detected by the short-circuit detection circuit at a start of machining, the second current being (i) smaller than the first current, (ii) insufficient to fuse the wire electrode even in a short-circuit state with the workpiece, but (iii) sufficient to form a discharge arc between the wire electrode and the workpiece, and the first current and the second current are discrete and separated from each other.
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8. A wire electric discharge machine, comprising:
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a discharge inducing circuit including a first DC power supply connected to a machining gap between a wire electrode and workpiece via a first switching element and a current limiting resistance; a current supply circuit including a second DC power supply connected to the machining gap via a second switching element; a voltage detection circuit that detects a voltage of the machining gap; a short-circuit detection circuit that detects a short-circuit state between the wire electrode and the workpiece based on the voltage detected by the voltage detection circuit; and a control circuit that controls on and off of the first switching element and the second switching element, wherein the control circuit is configured to supply a first current to process the workpiece, and a second current until a predetermined state is reached after the wire electrode and the workpiece reach an open state by a pulse voltage being applied to the machining gap when the short circuit is detected by the short-circuit detection circuit at a start of machining, the second current being (i) smaller than the first current, (ii) insufficient to fuse the wire electrode even in a short-circuit state with the workpiece, but (iii) sufficient to form a discharge arc between the wire electrode and the workpiece, and the first current and the second current are discrete and separated from each other.
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Specification
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Current AssigneeFanuc Corporation
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Original AssigneeFanuc Corporation
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InventorsHasegawa, Yasuo
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Primary Examiner(s)Evans, Geoffrey S
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Application NumberUS14/823,360Publication NumberTime in Patent Office1,211 DaysField of SearchUS Class CurrentCPC Class CodesB23H 1/024 Detection of, and response ...B23H 1/026 Power supply protection, e....B23H 7/02 Wire-cuttingB23H 7/04 Apparatus for supplying cur...
