Electrical discharge machining apparatus having means to sense the position of the electrode at the start of EDM machining of a workpiece. The apparatus includes means to measure the forward movement of the electrode during each machining cycle and regulate the backward retracting movement of the electrode to a preselected distance so as to compensate for erosion of the electrode during the machining cycle to thereby facilitate positioning of the electrode in the correct location for the next machining cycle. The apparatus includes a sensing device operable to transmit electrical pulses corresponding to incremental movements of the electrode and control circuitry which receives the pulses and controls subsequent movement of the electrode.

Apparatus for compensating for electrode wear in an electrical discharge machine

Structure for and method of electrical discharge machining with a wire electrode to produce small holes including completely controlling electrical discharge machining parameters such as voltage, reactance, current and servo speed with a programmable microprocessor, central processing unit sensing first sparking between the wire electrode and the workpiece and controlling depth of cut from the position of the electrode on spark initiation electrode feeding to replenish eroded electrode through clamping sequencing between an electrical discharge machine head and an electrode carrying slide thereon. In accordance with the invention there is also provided ultrasonic vibration of at least one of the workpiece, a wire electrode guide and the electrode during machining. Also, the slide is driven by a screw and nut combination including a plastic extruded between the screw and nut to remove backlash therefrom and the tapered end of the wire electrode is removed prior to electrical discharge machining therewith by machining with the tapered end of the electrode with a reverse polarity, that is with a high wear polarity, between the electrode and workpiece, and splitting of the wire electrode is substantially eliminated by increasing the pulse time of the cutting parameters and lowering the current thereof while flushing at a low velocity.

Structure for and method of electrical discharge machining

An electrical discharge boring machine including: a main unit (12) which is moved vertically relative to a workpiece (W); a rotary chuck (14) attached to the lower part of the main unit (12) for holding a hollow bar electrode (16); a guide (36) for slidably guiding the hollow bar electrode (16) near the workpiece (W); a nozzle unit (40) provided on the lower part of the guide for supplying a machining liquid; a rotary joint (28) for introducing the machining liquid into the hollow bar electrode; and a connection (34) for supplying electric power for electrical discharge machining to the hollow bar electrode.

Electrical discharge boring machine

An electrical discharge machining device that is used for both rotational EDM, such as tapping, and the like, and for conventional or non-rotational EDM applications The device includes a base support to which a carriage is slidably mounted, with a motor driven, rotating electrode assembly mounted thereon A threaded lead screw is removably coupled to the upper end of the rotating electrode assembly and a mating threaded collar is removably mounted on the support so as to receive the lead screw and thereby advance the carriage as the lead screw is rotated The lead screw and threaded collar are interchangeable with other lead screws and collars having different thread pitches, so as to regulate the advancement of electrodes having different thread pitches An electrode is mountable both on the rotating electrode assembly and on the carriage itself

Mechanical feed EDM machine for making threaded and nonthreaded bores

A method of machining a workpiece to a predetermined depth using an electrode machining discharge apparatus including electrodes which wear during the machining process. The machining of a workpiece to a first level is effected, after which the electrodes are withdrawn and a refeed member having a surface matching that of the workpiece is positioned for engagement with the electrodes, followed by the electrodes engaging the refeed member to align the ends thereof, after which the machining operation continues. The machining operations are in increments less than the depth to which the machining is to be effective, and several alignments of the electrodes may be required.

Method of machining a workpiece to a predetermined depth using a machining process in which machine tool wear occurs

Apparatus for compensating the electrode wear in an electric discharge machine tool wherein an end of electrode travel signal is generated by actuation of a limit switch. The limit switch is actuated by a lead screw which is physically connected to the electrode holding means. The lead screw is moved a predetermined distance away from the limit switch by a motor means on each operation of the electrical discharge machine (EDM).

Berger Allen

Papers

Electrode wear compensating apparatus for an electrical discharge machine