Abstract: The invention relates to electrical discharge milling machines using tool electrodes subject to longitudinal wear. The inventive discharge milling machine is equipped with a numerical controller executing at least one control cycle for compensating the wear considering the following steps: (a) determining the volume Q eroded by each discharge, (b) calculating the distance s travelled by the tool from one effective discharge to the next, (c) calculating the actual eroded linear volume M [m3/m] for at least one effective discharge, M forming a measurement sample from the values Q and s, (d) comparing said sample M with the corresponding set value C to generate an error D=C?M [m3/m], and (e) calculating and transmitting a command by the numerical controller intended to reduce this error D during the following cycle or cycles.

Abstract: The invention relates to electrical discharge milling machines using tool electrodes subject to longitudinal wear. The inventive discharge milling machine is equipped with a numerical controller executing at least one control cycle for compensating the wear considering the following steps: (a) determining the volume Q eroded by each discharge, (b) calculating the distance s travelled by the tool from one effective discharge to the next, (c) calculating the actual eroded linear volume M [m3/m] for at least one effective discharge, M forming a measurement sample from the values Q and s, (d) comparing said sample M with the corresponding set value C to generate an error D=C?M [m3/m], and (e) calculating and transmitting a command by the numerical controller intended to reduce this error D during the following cycle or cycles.

Abstract: An electroerosion machining device to machine a piece (14) by milling successive layers includes a member (30) to drive in rotation an electrode-tool (31) of tubular shape and a digital control unit (CN) to control the three-dimensional movement (x, y, z) between the electrode-tool and the piece (14). A regulation module (MR) is adapted to simulate the longitudinal wear of the electrode-tool and to compensate it along its path. According to the type of geometric configuration between the electrode-tool and the piece, namely the presence or absence of an opening below the electrode-tool and the presence or absence of one or two walls, different values of longitudinal wear are provided and transmitted to the digital control unit (CN). There is thus obtained a high precision and planarity of machining.

Abstract: An electroerosion machining device to machine a piece (14) by milling successive layers, comprises a member (30) to drive in rotation an electrode-tool (31) of tubular shape and a digital control unit (CN) to control the three-dimensional movement (x, y, z) between the electrode-tool and the piece (14). A regulation module (MR) is adapted to simulate the longitudinal wear of the electrode-tool and to compensate it along its path. According to the type of geometric configuration between the electrode-tool and the piece, namely the presence or absence of an opening below the electrode-tool and the presence or absence of one or two walls, different values of longitudinal wear are provided and transmitted to the digital control unit (CN). There is thus obtained a high precision and planarity of machining.

Abstract: Electrical discharge machining of a positively charged workpiece with a negatively charged wire electrode (2) by a pulse generator (3), with water as the dielectric fluid, generates a stray current known as "leakage current" that leads to a form of corrosion on the surface of the workpiece known as "anodic dissolution". A secondary circuit fed by a generator (5) and located between the workpiece and auxiliary electrodes (6), creates an equalizing current that cancels the leakage current and diminishes or eliminates anodic dissolution of the workpiece (1). The auxiliary electrodes (6) can be mounted on machining heads (7) with a non-conductive material (8) between the auxiliary electrodes.

Abstract: A method and apparatus for determining the amount of deflection, or curvature height, of an electrode wire during machining of a workpiece by the electrode wire in a travelling wire EDM apparatus. A parametr affecting the curvature height of the electrode wire is varied from a first value to a second value and the resulting variation .DELTA.f of the curvature height is measured. The measuring is effected by determining the difference between the length of the path travelled by the wire guide members and the length of the path travelled by the active portion of the wire. The ratio between the curvature height of the wire and the inverse of the relative variation of the parameter is subsequently determined. Preferably, a parameter independent of the machining speed is selected, such as the force of longitudinal traction exerted on the wire or the distance separating the two wire guide members.

Abstract: A method and apparatus for polishing a workpiece by electrical discharges by way of an electrode tool, machining pulses of relatively low power being obtained from a machining pulse generator. A cross-slide table provides the workpiece with a translation cyclical motion during polishing. Input control circuits enable the machine operator to program a chosen speed of translation for the cyclical motion, the radius of circular translation and the time of duration of machining. A counter counts the number of cycles being effected and a discriminator stops the pulse generator as soon as the chosen number of desirable cycles is obtained, such number being inversely proportional to the amplitude chosen for the translation motion.

Abstract: A unitary assembly supporting an electrode wire guide member and a machining fluid nozzle providing a jet of fluid coaxially disposed with the wire, in a travelling wire EDM apparatus. The unitary assembly is mounted on a plate connected through a universal swivel joint to the lower slide of a cross-slide table. Lateral displacements of the plate cause the unitary assembly to orient itself under the action of a pair of fingers mounted on the plate co-operating each with a ramp mounted on the cross-slide table such as the unitary assembly constantly remains coaxial with the electrode wire.

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: A process and apparatus for increasing the frequency of the effective machining electrical discharges between the electrode workpiece and the electrode tool of an EDM apparatus. The process of the invention consists in monitoring the electrical parameters in the machining zone between the electrodes such as to detect short circuits, and, when a short circuit is detected, in continuing monitoring the electrical parameters until monitoring indicates the disappearance of the short circuit, in cutting off the ongoing electrical discharge after a predetermined time interval following the moment at which said short circuit disappears and in re-establishing normal electrical voltage pulses after another time interval following the end of the discharge. The invention also provides appropriate apparatus for practicing the process.

Abstract: An EDM process and apparatus for effecting a cut in an electrode workpiece by means of an electrode tool wire, wherein consecutive current pulses are caused to flow through a machining gap between the electrode wire and the workpiece, and the electrode wire is maintained under traction in the machining zone and is displaced longitudinally and fed laterally through the machining zone. The electrical resistance of the wire is measured through the portion of the wire disposed in the machining zone, and the machining current or the force stretching the wire by exerting a traction thereon, or both, is adjusted such as to maintain the electrical resistance within a predetermined range. This adjustment insures a continuous control of the mechanical and thermal constraints exerted on the electrode wire as well as preventing rupture of the wire.

Abstract: Process and apparatus for eliminating short circuits occurring in the machining zone between an electrode workpiece and an electrode tool in the course of an electrical discharge machining operation. Short circuits, caused by bridging of the electrodes by metallic particles, are burnt by an auxiliary high intensity electrical discharge across the gap between the electrodes applied after a predetermined time interval, or time delay, from the beginning of a normal current pulse.

Abstract: Support and guiding means for a wire electrode in an electro-erosion machining apparatus comprising a V-block support and guide having two angularly disposed guiding surfaces substantially parallel to the wire electrode longitudinal axis mounted on a base automatically orientable radially about the wire longitudinal axis such that the axis of a linear cut through the workpiece or, alternatively, the tangent of a curvilinear cut substantially bisects the angle formed by the two angularly disposed guiding surfaces.