Mitsubishi Denki Kabushiki Kaisha

Tamio Takawashi

Shigeo Yamada

Toshimitsu Sakakibara

A control apparatus for an EDM machining device includes electrode a position control servo system provided with a zero order hold circuit. This circuit issues a position control instruction which is preset in an error counter which outputs an electrode difference signal used to drive the electrode. The difference signal is also applied to a processor or the like wherein it is added to the position control instruction and applied to the zero order hold circuit.

Electrospark machining control device

An EDM machining apparatus is provided with means for automatic shut off upon completion of a machining process, including a voltage variation pattern detector capable of discriminating electrode penetration of the workpiece. Several other machining parameters, such as machining solution flow and pressure, machining depth, and electrode speed and direction may be used is secondary or confirmation detection factors, so as to positively detect the time of electrode penetration, and halt the machining process.

Breakthrough detection means for electric discharge machining apparatus

In an electric discharge machine in which the machining gap between an electrode and a workpiece is maintained suitably by a control device having sampling, logic operation and holding functions, an up-down counter is provided for integration, over a predetermined period corresponding to the sampling period, servo signals from a discrimination circuit adapted to discriminate the conditions of the machining gap, so that sampling for all periods of time within the sampling period can be achieved.

Electric discharge machining control device

An electric discharge machining device is provided with detecting means operable to determine when a particular machining operation, e.g. the formation of a through-hole in a workpiece, has been completed. In all cases, the position of the electrode is monitored to determine the present machining depth, and whether this depth is the largest depth thus far achieved. The detection of an increasing machining depth is coupled with at least one other detection factor, such as electrode speed, machining fluid flow or machining fluid pressure, such that the penetration of the electrode through the workpiece can be positively sensed. In response to such an indication, a stop signal is output to the power supply unit, to end the machining operation.

A discharge machining apparatus wherein the workpiece is supported over an aperture in the work support plate on top of a tank at the machining station for cooperation with an electrode movable toward and away from the workpiece in alignment with the aperture. A machining solution recirculation device injects the solution into the tank and removes the solution from the tank at a greater rate than it is injected into the tank. Additional fluid is directed into the tank through the aperture between the workpiece and electrode. An additional conduit having a solenoid controlled valve is provided for supplying an excess of solution to the tank upon raising of the electrode to overflow the tank and remove all sludge and combustible gases. The exhaust pipe for the solution is also adjustably mounted within the tank to more effectively position the inlet of the exhaust pipe for the optimum removal of combustible gases. A pressure release valve is provided in the side wall of the tank to vent explosive gases and prevent damage to the workpiece and electrode.

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Aichi, Japan

Tamio Takawashi