A primary power supply charges a capacitor by turning on a switching element and, upon completion of charging, turns off the switching element. Then, an AC pulse voltage is applied to the gap between a wire electrode and a workpiece by alternately turning on and off a switching element present in a secondary power supply. After a dielectric breakdown occurs between the wire electrode and the workpiece, the switching element is turned on to connect the capacitor so that the capacitor supplies a pulse current for machining.

In a method of welding a cut-out part with a workpiece at a preselected area in a thickness direction of the workpiece in a wire electrical discharge machining to retain temporarily or tentatively the part on the workpiece, a wire electrode 5 tilted in posture cuts the workpiece 6 to form a slant cutting surface 30 at a spark discharge location in a desired contour 21 in the workpiece 6. The wire electrode 5 after kept in an upright posture executes the welding process on the workpiece 6 along the slant cutting surface. A plurality of the welded spots is formed over a preselected length at preselected areas in the thickness direction of the workpiece 6. Even if the cut-out part 26 weighs more or the spark discharge is executed on the workpiece 6 overlapped one on the other, the welding spot 20 is formed in the thickness direction of the workpiece 6 adequately depending on the working situation to tentatively retain the cut-out part 26 on the workpiece 6.

In a method of welding a cut-out part with a workpiece at a preselected area in a thickness direction of the workpiece in a wire electrical discharge machining to retain temporarily or tentatively the part on the workpiece, a wire electrode 5 tilted in posture cuts the workpiece 6 to form a slant cutting surface 30 at a spark discharge location in a desired contour 21 in the workpiece 6. The wire electrode 5 after kept in an upright posture executes the welding process on the workpiece 6 along the slant cutting surface. A plurality of the welded spots is formed over a preselected length at preselected areas in the thickness direction of the workpiece 6. Even if the cut-out part 26 weighs more or the spark discharge is executed on the workpiece 6 overlapped one on the other, the welding spot 20 is formed in the thickness direction of the workpiece 6 adequately depending on the working situation to tentatively retain the cut-out part 26 on the workpiece 6.

The present invention relates to an electric discharge machining device. The electric discharge machining device includes: a first switch provided between the positive pole of a power supply and a work piece; a second switch provided between the negative pole of the power supply and the work piece; a third switch provided between the negative pole of the power supply and a tool electrode; a fourth switch provided between the positive pole of the power supply and the tool electrode; and a pulse generating device. In order to supply current pulses with a straight polarity, the pulse generating device repeatedly switches on and off either the first or third switch while the other switch is on. In order to supply current pulses with a reverse polarity, the pulse generating device repeatedly switches on and off either the second or fourth switch while the other switch is on.

The present invention relates to an electric discharge machining device. The electric discharge machining device includes: a first switch provided between the positive pole of a power supply and a work piece; a second switch provided between the negative pole of the power supply and the work piece; a third switch provided between the negative pole of the power supply and a tool electrode; a fourth switch provided between the positive pole of the power supply and the tool electrode; and a pulse generating device. In order to supply current pulses with a straight polarity, the pulse generating device repeatedly switches on and off either the first or third switch while the other switch is on. In order to supply current pulses with a reverse polarity, the pulse generating device repeatedly switches on and off either the second or fourth switch while the other switch is on.

In a wire electric discharge machine, a control unit is configured to deposit constituents of a wire electrode between a workpiece and a portion to be cut off from the workpiece to bond the workpiece and the portion to be cut off by outputting a signal for making an output voltage of a variable DC power supply lower than during normal machining and the on-time of a second switching element longer than during the normal machining, at least in a part of a machining path.

In a wire electric discharge machine, a control unit is configured to deposit constituents of a wire electrode between a workpiece and a portion to be cut off from the workpiece to bond the workpiece and the portion to be cut off by outputting a signal for making an output voltage of a variable DC power supply lower than during normal machining and the on-time of a second switching element longer than during the normal machining, at least in a part of a machining path.

High-speed wire electrochemical-discharge cutting method (HS-WECDM), in which a work piece is processed by means of a wire electrode, in which consecutive negative polarity pulses are applied at said wire electrode, thereby at least partially developing discrete electrical discharges, wherein the method further includes, applying positive polarity pulses at the wire electrode between the negative pulses, and that an ignition occurring with each positive polarity pulse is immediately detected, and that the positive polarity pulses are immediately interrupted.

A device for machining a part by electrical discharge machining using an electrode wire. The device includes equipment for holding the electrode wire taut and driving the wire to translate longitudinally, in proximity to the part to be machined, in a sparking zone. The device further includes equipment for making a stream of dielectric liquid flow through the sparking zone between the electrode wire and the part to be machined. An electrical power source generates electrical pulses that cause sparks in the sparking zone between the electrode wire and the part to be machined. The quantity of gas bubbles present in the sparking zone is measured, and a signal is produced, representative of the quantity of bubbles, the signal being delivered to a controller. The controller modifies machining parameters so as to maintain the value of the signal within a suitable range.

A device for machining a part by electrical discharge machining using an electrode wire. The device includes equipment for holding the electrode wire taut and driving the wire to translate longitudinally, in proximity to the part to be machined, in a sparking zone. The device further includes equipment for making a stream of dielectric liquid flow through the sparking zone between the electrode wire and the part to be machined. An electrical power source generates electrical pulses that cause sparks in the sparking zone between the electrode wire and the part to be machined. The quantity of gas bubbles present in the sparking zone is measured, and a signal is produced, representative of the quantity of bubbles, the signal being delivered to a controller. The controller modifies machining parameters so as to maintain the value of the signal within a suitable range.