Abstract: A process and apparatus for monitoring machining conditions in a travelling wire EDM apparatus. The resistivity of the machining fluid in the machining zone is measured and is compared to a reference value. A signal is provided as soon as the measured resistivity increases beyond the reference value and the signal is used for decreasing or interrupting the machining current.

Abstract: A support mechanism for a workpiece cut off by electrical discharges in a travelling wire EDM apparatus. The workpiece is supported between support members provided with clamps. One support member is controllably pivotable around a horizontal axis, while the second support member is displaceable vertically and horizontally along crossed axes. In addition, the second support member may be rotated around a vertical axis. Through appropriate sequential operation of the clamps and relative displacement of the support members, the areas of the workpiece clamped by the clamps may be changed at will, and the cuttings from the workpiece may be supported by one of the clamp members to prevent the fall of the cuttings at the end of a cutting operation.

Abstract: A method and apparatus for threading the electrode wire of a travelling wire EDM apparatus through an aperture in a workpiece. Prior to threading the wire through the aperture in the workpiece, the wire is continuously annealed and straightened and is passed through a nozzle to which fluid under pressure is supplied for forming a jet stream at the outlet of the nozzle. Prior to a threading or rethreading operation the wire, which is continuously fed by pulling by a wire conveyor mechanism, is cut off proximate to the outlet of the nozzle. The jet stream is aimed at the aperture in the workpiece and the end of the wire is fed through the aperture, while being maintained coaxially by the jet stream.

Abstract: A method and apparatus for threading or rethreading the end of an electrode wire through an aperture in a workpiece in which a cut is to be effected, by electrical discharges in a machining zone between the electrode wire and the workpiece. While the end of the electrode wire is brought in proximity with the inlet of the aperture in the workpiece, the end of the electrode wire is disposed in a pressurized fluid flowing towards the inlet of the aperture in the workpiece such that the end of the electrode wire is automatically centered relative to the aperture, and threading the end of the wire through the aperture.

Abstract: A method and apparatus for threading the electrode wire of a trailing wire EDM apparatus through a starter hole or aperture in the workpiece or through the machined slot, the workpiece being submerged in a machining fluid. A chamber is disposed in contact with the workpiece under the workpiece, the chamber being in communication with an end of the aperture through the workpiece. The chamber is connected to a source of suction, with the result that fluid being sucked through the aperture in the workpiece converges towards the inlet of the aperture and guides the end of the electrode wire into the inlet of the aperture.

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: In a travelling wire EDM apparatus, a unitary assembly of at least one of the electrode wire support members and a machining fluid nozzle disposed coaxially to the wire is installed on a plate which is displaceable such as to provide the electrode wire passing through the machining zone in the workpiece with an appropriate inclination. Inclination of the unitary assembly of the electrode wire support member and machining fluid nozzle is obtained by a swivel member mounted on the plate and oriented by a tube through which the electrode wire is passed. The tube is supported along its length by a pivot which is at all times disposed symmetrically to the electrode wire lower support member relative to a plane of symmetry. The unitary assembly is also supported by a swivel joint member interconnected to the first swivel joint member such that the angular displacement of the respective swivel joint members are symmetrical.

Abstract: An orientable unitary assembly for the support and guide member for the electrode wire of a travelling wire EDM apparatus, the assembly also comprising a nozzle supplying a machining fluid jet coaxial to the electrode wire. The assembly is supported by a cross-slide table permitting to incline the axis of the wire relative to a wire support and guide member disposed on the other side of a workpiece. The displacements of the slides of the cross-slide table are effected by leadscrews each driven by a servo motor, and the orientation of the assembly is controlled by the same servo motors via second screwthreads of different pitch each displacing a nut which, through a push-rod, controls the inclination of the assembly.

Abstract: In the electrical discharge machining of the surface of a recess in a workpiece electrode to a shape corresponding to that of a tool electrode, the electrodes are relatively displaced, during a finishing phase of machining, along an axis of penetration and simultaneously in a plane perpendicular to the axis of penetration with a cyclic translational movement whose amplitude increases with the penetration of the tool in the workpiece. This provides a virtual 3-dimensional dilatation of the tool as it advances, and enables control of the sparking in both the frontal and lateral parts of the machining zone, such that the shape of the machined portion is an image of the tool shape. The cyclic translational movements can be obtained with an eccentric member whose eccentricity relative to a shaft is controlled by limiting axial movement of the shaft at a position corresponding to a predetermined penetration.

Abstract: An adjustable and controllable electrode wire support and guide mechanism for traveling wire EDM apparatus wherein an electrode wire, longitudinally fed, is stretched between a pair of support and guide members, and wherein at least one of the support and guide members is in the form of a helically grooved cylindrical member directly driven by a servo-motor. The helical groove defines guiding surfaces for the electrode wire which is in engagement with opposite sidewalls of the groove and, by rotating the helically grooved support and guide member by the servo-motor, the electrode wire is caused to take a predetermined inclination relative to the workpiece.

Abstract: A machine tool provided with a movable table supported by a stationary table, the movable table being displaceable relative to the stationary table in all directions and being supported by the stationary table by pressurized fluid bearing. The movable table is positioned by at least three actuators pivotally connected at one end to the stationary table and at their other end to the movable table such that the lengths of the actuators, controlled by an appropriate numerical control system, result in a predetermined position of the movable table relative to a reference position.

Abstract: A process and apparatus for accurately controlling the dimensions of a workpiece machined by EDM, by developing a linear function of the average value of the delay between the application of voltage pulses and the flow of electrical discharges through the gap between an electrode tool and an electrode workpiece. The function is linear and is an inverse function of the machining gap width to the logarithm of the average delay time. Two measures effected under well-determined machining conditions permit to develop the function with precision under such conditions, and it is thus possible to instantaneously know the real machining gap width by determining only the average value of the triggering delay.

Abstract: A threading mechanism for threading the electrode wire of a travelling wire EDM apparatus, the end of the electrode wire being passed through a starter hole or aperture in the workpiece prior to effecting a cutting operation in the workpiece, wherein the entrance throat to the wire conveying mechanism adapted to take hold of the wire after passage through the starter aperture is offset laterally relative to the axis of the starter hole such as to laterally displace the wire to engage the wire with a guiding surface and a current feeding surface which are also offset relative to the axis of travel of the wire through the starter aperture.

Abstract: A method and apparatus for machining, by electrical discharges, an electrode workpiece by means of an electrode tool, wherein machining fluid supplied by a nozzle to the machining zone between the electrode tool and the electrode workpiece is returned to a tank and circulated by a pump from the tank to the nozzle through two lines, one provided with a filter and the other having no filter but controlling the flow of fluid therethrough and comprising a solid particle proportioning device. The flow rate and proportioning device is controlled by an electrical signal for regulating the concentration of solid particles in suspension in the fluid, and the adjustment for the concentration of solid particles is effected on the basis of measuring the average delay of triggering of the machining electrical discharges.

Abstract: A vented heat transfer tube assembly comprising a pair of fluid circulation tubes disposed co-axially one within the other, the inner tube being double-walled and held substantially concentric within the outer tube by a plurality of pairs of diametrally opposed depressions or dimples formed in the peripheral surface of the outer tube at regular intervals. Each depression or dimple projects inwardly such as to engage and indent the peripheral surface of the inner tube and to cause a corresponding portion of the inner tube to bulge inwardly during forming of the dimples in the periphery of the outer tube.

Abstract: In the electrical discharge machining of the surface of a recess in a workpiece electrode to a shape corresponding to that of a tool electrode, the electrodes are relatively displaced, during a finishing phase of machining, along an axis of penetration and simultaneously in a plane perpendicular to the axis of penetration with a cyclic translational movement whose amplitude increases with the penetration of the tool in the workpiece. This provides a virtual three-dimensional dilatation of the tool as it advances, and enables control of the sparking in both the frontal and lateral parts of the machining zone. The cyclic translational movements are obtained from a rotatable shaft having an axis parallel to the axis of penetration and an eccentric member cooperating with the rotatable shaft to slide relative to the shaft in a direction forming a predetermined angle with the direction of penetration, the eccentric member being rotated in unison with the shaft about its axis.

Abstract: In the electrical discharge machining of the surface of a recess in a workpiece electrode to a shape corresponding to that of a tool electrode, a method whereby the electrodes are relatively displaced, during a finishing phase of machining, along an axis of penetration and simultaneously in a plane perpendicular to the axis of penetration with a cyclic translational movement whose amplitude increases with the penetration of the tool in the workpiece. This provides a virtual 3-dimensional dilatation of the tool as it advances, and enables control of the sparking in both the frontal and lateral parts of the machining zone such that the shape of the machined portion is an image of the tool shape. The cyclic translational movements can be obtained with an eccentric member whose eccentricity relative to a shaft is controlled by limiting axial movement of the shaft at a position corresponding to a predetermined penetration.

Abstract: In the electrical discharge machining of the surface of a recess in a workpiece electrode to a shape corresponding to that of a tool electrode, the electrodes are relatively displaced, during a finishing phase of machining, along an axis of penetration and simultaneously in a plane perpendicular to the axis of penetration with a cyclic translational movement whose amplitude increases with the penetration of the tool in the workpiece. This provides a virtual 3-dimensional dilatation of the tool as it advances, and enables control of the sparking in both the frontal and lateral parts of the machining zone, such that the shape of the machined .[.position.]. .Iadd.portion .Iaddend.is an image of the tool shape. The cyclic translational movements can be obtained with an eccentric member whose eccentricity relative to a shaft is controlled by limiting axial movement of the shaft at a position corresponding to a predetermined penetration.

Abstract: A process and apparatus for achieving relative displacement between the electrode tool and the electrode workpiece of an EDM apparatus about a closed or looped path at a speed varying as a function of the machining gap width, such as to remove material from the machined surfaces at a substantially constant material removal rate.

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.