Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Denki K.k.

Yoshio Ozaki

Akihiro Goto

Mitsuyoshi Wada

Takeshi Yatomi

Kazuo Tsurumoto

Yutaka Tanaka

Atsushi Taneda

Morihisa Nishikawa

Tatsushi Sato

Yoshihito Imai

Masahiro Yamamoto

Yoshihide Kinbara

Shigeo Yamada

Toshiaki Tanaka

Masahiro Nakata

Kooji Akamatsu

An electrical discharge machine for applying a pulsed voltage to a machining gap between an electrode and a workpiece disposed opposite thereto. An insulating dielectric fluid, such as oil or water mixed with a compound additive, is disposed in the gap. A positive polarity voltage and an opposite polarity voltage are applied via switches and respective impedances to the machining gap in order to generate a discharge for machining the workpiece. A pulse having a first polarity is applied to machine the workpiece and a pulse having a second polarity is applied when the first polarity pulse is not applied. A misfire pulse detector detects an undesired drop in the machining voltage by determining whether the first polarity voltage is in a range between two voltages, the first of which has a magnitude greater than the magnitude of the machining gap during discharge and the second of which has a magnitude greater than the magnitude of the first voltage.

Bipolar electrical discharge machine which detects misfire

An electrical discharge machine for applying a pulsed voltage to a machining gap between an electrode and a workpiece disposed opposite thereto. An insulating dielectric fluid, such as oil or water mixed with a compound additive, is disposed in the gap. A positive polarity voltage and an opposite polarity voltage are applied via switches and respective impedances to the machining gap in order to generate a discharge for machining the workpiece. A pulse having a first polarity is applied to machine the workpiece and a pulse having a second polarity is applied when the first polarity pulse is not applied. The time of application of the second polarity pulse is increased depending upon the number of short-circuits detected between the electrode and the workpiece.

Bipolar electrical discharge machine which adjusts voltage polarity

A method and apparatus for detecting the build up of tar on the electrode or workpiece in an electric discharge machine is achieved by determining the difference between a machining gap impedance found from dielectric fluid resistivity and an electrode area and a machining gap impedance actually measured.

Electrical discharge machine with tar build-up detector

An electrical discharge machine for applying a pulsed voltage to a machining gap between an electrode and a workpiece disposed opposite thereto. An insulating dielectric fluid, comprising an oil or water with compound additive, is disposed in the gap. A positive polarity voltage and an opposite polarity voltage are applied via switches and respective impedances to the machining gap in order to generate a discharge for machining the workpiece. The impedance values may be selectively set and the switching of the voltages controlled such as to apply a positive polarity voltage at the stop time of an opposite polarity pulsed voltage, whereby the average voltage approximates a predetermined value, preferably zero, during the stop time. Voltage control during the stop time will result in high speed and finish, especially for control in connection with a jump operation.

Electrical discharge machine with pulses of both polarities

An electrical discharge machine for applying a pulsed voltage to a machining gap between an electrode and a workpiece disposed opposite thereto. An insulating dielectric fluid, comprising an oil or water with compound additive, is disposed in the gap. A positive polarity voltage and an opposite polarity voltage are applied via switches and respective impedances to the machining gap in order to generate a discharge for machining the workpiece. A high frequency alternating current voltage is applied between the electrode and the workpiece when the first polarity and second polarity voltages are not being applied.

Electrical discharge machine

An electrical discharge machine for applying a pulsed voltage to a machining gap between an electrode and a workpiece disposed opposite thereto. An insulating dielectric fluid, including either oil or water with a compound additive, is disposed in the gap. A first voltage is applied to the machining gap. If a predetermined period of time passes and a discharge has not occurred at the machining gap, then a second voltage, opposite in polarity to the first voltage, is applied to the machining gap.

Electrical discharge machine which uses voltages of opposite polarity

A machining pulse control apparatus applies a first polarity pulse voltage during a machining operation and a second opposite polarity voltage in a machining stop period in which the electrode is moved away from and toward the workpiece during a jump operation. Preferably, the second opposite polarity is applied for a period of time sufficient to maintain the voltage across the machining gap at zero voltage. The amount of direct current voltage applied during the jump operation is adaptively controlled.

Electrical discharge machine with an opposite polarity voltage applied

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.

Electrical discharge machine and machining method therefor

A method for electrochemical machining a work piece using an electrochemical machining device including a tool electrode opposing the workpiece across a predetermined machining gap and a device for supplying a pulse current to the machining gap via electrolyte provided in the machining gap includes the steps of determining a predetermined pulse current having a predetermined pulse width, selecting a plurality of partial pulse currents each having a predetermined partial pulse period, calculating a plurality of rest periods based on said partial pulse widths and applying the partial pulse currents, each of the partial pulse periods separated by at least one of the rest periods. According to the method of the present invention, the predetermined pulse width is in the range of about 10-50 msec. An electrochemical machining device, which includes a control unit, a tool electrode, a machining tank and circuitry for supplying a predetermined amount of the electrolyte to the machining gap during a dwell time between two sequential pulse currents to remove residual electrolytic products from the machining gap and the tool electrode is also disclosed.

Electrochemical machining process and equipment

A waveform control device for an electrical discharge machine apparatus which supplies current pulses to the gap between an electrode and a workpiece for machining of the workpiece. A first D.C. source, which supplies at least a part of a voltage that is applied across the gap, is connected in parallel with first and second circuits comprising a series connection of a switch and a diode. Connected between a first and second series circuit is a switched conductive circuit which, together with an auxiliary D.C. source, maintains the current flow at a base current level. Control of operation of the switches in the first and second circuits permit a controlled discharge of current across the gap while permitting the output voltage to be clamped at a safe level. A plurality of inductive circuits may be used to provide selectivity, where the inductances are different and to provide further control of the discharge current shape. A variable inductance, whose value is proportional to the output peak current, may be used to control current ripple.

Waveform control device for electrical discharge machining apparatus

Electric discharge machining method and device

Electric discharge machine with control of the machining pulse's current

Power source for wire cut electrical discharge machining

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.

Power supply unit for electric discharge machine

A command average machining current It(n) corresponding to change of a workpiece thickness is given by the following equations: ##EQU1## wherein the reference Ia(n) designates an actual average machining current Ia(n) at the workpiece thickness (Tn); It(n) designates an average machining current of the control command; Fn designates an actual machining feed rate; Ia(o) designates an actual average machining current at the initiation of the machining; S(o) designates a machining width; and To designates a workpiece thickness. The command average machining current It(n) is compared with the actual average machining current and the electric condition is changed and controlled to approach the actual average machining current to the command average machining current It(n) thereby controlling the work groove width to be constant in an electric discharge machining of the workpiece with a wire electrode.

Growing community of inventors

Aichi, Japan

Yoshio Ozaki