Abstract: A discharge-processing power-source assembly, in which a processing liquid is interposed at a minute gap defined between a workpiece and an electrode, and processing is executed by discharge energy, comprises a D.C. power source supplying electric energy to the minute gap, switching elements for converting D.C. voltage from the D.C. power source to pulse voltage, and a snubber circuit for protecting the switching elements. The discharge-processing power-source assembly further comprises a relay contact for cutting off the snubber circuit when a switching frequency is high.

Abstract: Accurate control of the tension of a wire electrode in a wirecut electrical discharge machine is achieved by eliminating a direct-current (DC) component from a speed difference signal between a braking section and a recovery section of the machine. The DC component of the speed signal which is eliminated is associated with the stretching of the wire electrode while under tension. As a result, the tension can be maintained constant dynamically as well as statically, thereby improving machining accuracy.

Abstract: A wire cut electric discharge machining apparatus capable of machining a workpiece with a machining solution to produce a work having a desired shape. The work is magnetically attracted to be held and conveyed to a desired position by one of a pair of nozzles through which the machining solution is supplied to an interelectrode gap between the workpiece and a wire-shaped electrode. Since the attraction condition is controlled to be maintained unchanged, it is possible to move and convey the work and the like to the desired position with high accuracy and safety.

Abstract: In an electric discharge machine having a main switching circuit 24 for supplying a current high in current peak value between which are an electrode 10 and a workpiece 12, and an auxiliary switching circuit 26 for supplying a current low in current peak value between the electrodes, to intermittently cause electric discharge between the electrodes which are the electrode 10 and the workpiece; a voltage is applied across the electrodes by the auxiliary switching circuit 26, and when no electric discharge occurs between the electrodes before a decision set time of 1 to 4 .mu.

Abstract: In a power source for wire cut electrical discharge machining by which a pulsating voltage which is higher than a discharge voltage and has a quiescent time is applied to cause an intermittent discharge between the poles defined by an electrode wire and the material to be machined, the quiescent time or the discharge current continuing time is controlled in accordance with the number of times of a repeated discharge in order to restrict an average current flowing between the poles per unit time to a predetermined level to prevent the breakage of the wire and increase the machining speed.

Abstract: The present invention relates to a power supply unit for an electric discharge device of the type used in electric discharge machining. First and second DC sources are employed, and the output of the two sources are applied to the machining gap, by way of main and auxiliary switching circuits. The output of the first DC source is applied to the machining gap initially, and a discrimination device operates to detect whether normal electric discharge takes place. The second DC source is applied to the machining gap in dependence upon the operation of the main switching circuit, the operation of which is in turn dependent upon the output of the discrimination circuit and a delay pulse derived from an oscillator which initiates the closure of said auxiliary switching circuit.