Abstract: A power supply unit for wire electrical discharge machining using an ac high-frequency power supply for applying an ac high-frequency voltage between a wire electrode (1a) and a workpiece (2) includes a high-frequency oscillation and amplification circuit (4) and a pulse power supply (5) which is an ac-high-frequency-voltage intermittently supplying means for effecting the application of the ac high-frequency voltage between the electrode and the workpiece and a pause thereof. In wire electrical discharge machining using this power supply unit for wire electrical discharge machining, it is possible to suppress the vibration of the wire electrode (1a) due to the electrostatic force acting between the wire electrode (1a) and the workpiece (2), making it possible to improve the straightness accuracy of a machined surface of the workpiece (2) and make surface roughness small.

Abstract: The electric discharge machining apparatus comprises a wire electrode for machining a workpiece, and a first voltage applying unit for applying a voltage pulse. The voltage pulse is such that it has a rise time longer than a discharge formative time lag when a rectangular voltage pulse is applied when a distance between the workpiece and the wire is an average value in machining and rises up to the same voltage value as the rectangular voltage pulse.

Abstract: An electric discharge machine apparatus has a numeric control unit which can optimally set jumping conditions without forcing the user to perform any complicated setting operation. The numeric control unit calculates an optimal jumping velocity from a value indicating a machine-allowable load for the electric discharge machining apparatus, a machining area according to the electric discharge machining conditions, and a machining gap length computed from the electric discharge machining conditions. The machining area is computed by the ratio between the proceeding velocity in machining and a discharge pulse frequency. The machining gap length is computed according to the current value of a machining current pulse as well as to a voltage loaded to the machining gap.

Abstract: A power supply unit for a discharge machining apparatus which eliminates overshooting in current rise and improves the electrode consumption characteristics by preventing an operational amplifier as well as a current control element from being saturated, thereby eliminating overshooting during the rise time of the machining current, by clamping the output voltage of the operational amplifier during the stand-by time for electric discharge. The output is clamped by a plurality of resistors and diodes to a state where the output voltage is higher than a power-supply voltage (the output clamp level is set by a resistor). Namely, during the stand-by time when inverted amplification (feedback) via a resistor in an operational amplifier is being carried out, a constant state of feedback is maintained by the diodes.

Abstract: In a power supply apparatus of an electrical discharge machine, a power supply high in efficiency and small in current ripple is provided to achieve a power supply reduced in size and price. In addition, a switching power supply system is used jointly to generate an optional waveform. A first switching device is switched on/off in an optional cycle under the control of a current command value signal corresponding to the waveform shape of a current pulse to be supplied to a machining gap, whereby an optional shape of current pulse is supplied to the machining gap and a current component which compensates for a current ripple generated by said switching at the time of supplying said current is superimposed on said optional shape of current pulse and is supplied to the machining gap.

Abstract: A method and apparatus for detecting and controlling the operation of an electric discharge machine for machining a workpiece. The machining is conducted by generating pulse discharges at a machining gap formed by a machining electrode and the workpiece opposed to each other. The alternating-current components or high frequency components of at least one of the current, voltage and impedance of the machining gap, the rectified components thereof, or amplitude, frequency or other signal characteristics thereof are detected and processed for control of the machining. The processing may include frequency analysis, pulse counting, threshold detection and the like using analog and digital processing.

Abstract: An electronic discharge machining system in which an electrode and workpiece are coupled between first and second power supply circuits. The first power supply circuit includes a DC power source, a switching element, and a current limiting resistor, which are controlled by a control circuit. The second power supply circuit includes a machining gap status detecting DC power supply, which is composed of a voltage source and a controllable output impedance, and a switching element, all of which are controlled by a control circuit. The secondary power supply circuit is controlled by the control circuit, which sets and controls the voltage source and/or the output impedance of the machining gap status detecting DC power supply in accordance with machining conditions, such as the voltage detected across the machining gap.

Abstract: In a wire cut electric discharge machine, a plurality of magnetic field generating coils are arranged on the path along which a wire electrode is introduced into a workpiece, currents different in phase from one another are applied to the magnetic field generating coils thus arranged, so that the wire electrode is driven by the electromagnetic induction caused by the shifting magnetic fields which are produced by the magnetic field generating coils, whereby the wire electrode is smoothly fed without deformation. The leakage of magnetic flux is reduced by using a wire electrode made of magnetic material. The magnetic field generating coils are wound coaxial with the wire electrode, or they are provided so as to form magnetic fields perpendicular to the direction of insertion of the wire electrode, whereby the resultant wire electrode feeding device is simple in structure, but can produce a strong force of driving the wire electrode.

Abstract: An interelectrode distance controlling device in an electric discharge machining apparatus which is capable of automatically setting the proportional constant for a drive unit for driving an electrode to machine a workpiece, so that the machining is performed with high accuracy and smoothly. Such an interelectrode distance controlling device, detects the oscillation of a system in an electric discharge machining apparatus during machining, and the device automatically sets the proportional constant to an optimum value in a range within which no oscillation occurs with the system.

Abstract: An electric discharge machining device, in which a pulse voltage is repeatedly applied between electrodes, which are an electrode and a workpiece to be machined, to cause electric discharge between the electrodes and thereby machine the workpiece. The electric discharge machining device includes a switching device (4) connected between a power source and the machining section, for controlling energy supplied by the power source; interelectrode impedance detecting apparatus (10) for detecting an interelectrode impedance affected by the variation in place of electric discharge which takes place between the electrodes; discharge detecting apparatus for detecting when electric discharge takes place between the electrodes; and a control device (18).