Abstract: The process and device for machining by electroerosion are arranged so as to produce during each erosive discharge the following succession of phases: a delay phase (tD) during which an alternating voltage is applied between the tool and the piece at a frequency such that the ions present in the machining fluid follow shorter oscillating paths than the machining distance, separating the tool and the piece, a sparking phase (tA) including a lag period (tR) and an erosive discharge phase (tC) and a pause phase (tB) during which no voltage is applied so that the ionized path through the machining fluid disappears. There is thus obtained the complete suppression of all phenomena of electrolysis and deterioration of the tool and of the piece and a high efficiency of triggering and machining.

Abstract: A wire electrode arrangement for electroerosion cutting includes an elongated core. Multiple electrode elements are arranged sequentially along the elongated core. The electrode elements are separated by gaps and are mutually insulated.

Abstract: A machine which uses electroerosion with an electrode piece by means of a stretched electrode wire unwound between two wire guides with at least one device with crossed movements to fabricate other pieces, these wire guides are equipped to displace in a parallel plane to that of the trajectory and to cut off in this way by inclining the wire to a predetermined angle in relation to a neutral perpendicular axis to this plane and to make it pivot on itself around a mobile axis parallel to this neutral axis passing by this guide and displacing itself with it. It presents also an equipped device in order to subjugate the rotation of the guide wire to displacements of the device to crossed movements. At least one of the wire guides is in preference to an open guide open to a gap.

Abstract: An apparatus and method for preventing machining errors due to changes in the inclination of the electrode wire in a travelling wire EDM apparatus wherein the electrode wire effectuates a cut on a workpiece such that the workpiece is provided with a bevel or taper on its peripheral surface. A test or trigger electrical pulse of low power is applied between the electrode wire and the workpiece in the machining zone and the location where the trigger electrical pulse occurs along the length of the electrode wire in the machining zone is detected and the trigger electrical pulse is converted into a machining electrical discharge, or not converted, according to the speed of feed of the electrode wire at such location while being displaced transversely along the cutting path in the course of a change of inclination of the electrode wire.

Abstract: In a travelling wire EDM apparatus, the electrode wire is divided into a plurality of sectors disposed along the active length of the electrode wire, and the numbers of electrical discharges occurring in each of the sectors from a predetermined starting time is detected. Those numbers are compared to reference values to determine the difference between the numbers of detected electrical discharges and corresponding reference values. In its simplest form, all the reference values are equal to the average value of the number of electrical discharges per sector. If one or more of the differences is higher than a predetermined threshold, an adequate modification of the machining parameters is effected as a function of the difference.

Abstract: A travelling wire EDM apparatus wherein a workpiece is cut by electrical discharges by a travelling wire electrode, relative motion of the workpiece and the wire electrode being controlled by a numerical control unit which, in addition, controls transverse oscillations of the electrode wire relative to the workpiece along the cutting path. The energy of the electrical discharges is varied as a function of the amplitude of the transverse oscillations of the electrode wire relative to the workpiece such as to obtain maximum electrical discharge energy when the amplitude of vibration of the electrode wire is at a minimum and minimum energy when the amplitude of vibration of the electrode wire is at a maximum.

Abstract: A device for applying electrical current and voltage pulses between an electrode workpiece and an electrode tool, in the form of a wire or ribbon, in a travelling wire EDM apparatus, wherein a pulse generator providing such current and voltage pulses is connected across the electrodes. The travelling wire electrode is supported and guided by a pair of support and guide members and the pulse generator is connected across one of the support and guide members of the travelling wire electrode and the workpiece. A capacitor is connected across two contact members one engaged with the travelling wire electrode and the other with the workpiece, and is supported by one of the travelling wire support and guide members. The effect of the capacitor connected directly across the machining gap is to reduce considerably to a negligible value the inductance of the electrical circuit applying the current and voltage pulses across the electrodes.

Abstract: An electrode for machining a workpiece by electrical discharges, the electrode having an active surface comprising at least 50% by weight of a metal or alloy selected from the group consisting of zinc, cadmium, tin, lead, antimony and bismuth. Preferably, the active surface is in the form of a coating electrolytically plated on the surface of a conventional metallic wire having good mechanical characteristics. The invention contemplates continuously plating a metallic filament electrode such as an electrode wire with the active surface coating after the electrode wire has been used for machining a workpiece by EDM.

Abstract: A process and apparatus for monitoring the efficiency of an EDM machine by providing an electrical magnitude or signal representing the current flow actually used for machining or, in the alternative, the actual material removal rate. Several circuits are disclosed permitting to provide the operator of an EDM machine with a visual display of the practical efficiency of the machine during a machining operation.

Abstract: In electrical discharge machining, an electrode is displaced towards a workpiece at a rate controlled as a function of the sparking conditions. The relative position of the electrode and workpiece is measured and, beyond a preset reference relative position, advance of the electrode is slowed as a function of the displacement past the reference position, or is stopped at the reference position, while continuing sparking and allowing withdrawal of the electrode if necessitated by the sparking conditions.

Abstract: An electro-erosion process and apparatus for improving the rate of material removal from a workpiece and for decreasing the rate of wear of the electrode tool in an electrical discharge machining apparatus, by controlling the average value of the machining current across the machining gap between the electrode tool and the workpiece by providing cut-off time intervals between consecutive pulse trains at a frequency of at least 200 Hz, and by controllably varying at least one of the parameters of operation consisting of the number of the pulses included within a single pulse train, the duration of application of said pulses within a single pulse train, and at least the longest of the intervals of time comprised between two consecutive voltage pulses.

Abstract: In electrical discharge machining, an electrode is displaced towards a workpiece at a rate controlled as a function of the sparking conditions. The relative position of the electrode and workpiece is measured and, beyond a preset .[.reference.]. relative position, advance of the electrode is slowed as a function of the displacement past the reference position, or is stopped at the reference position, while continuing sparking and allowing withdrawal of the electrode if necessitated by the sparking conditions.