Abstract: An EDM machine in combination with a wire sectioning device. The wire sectioning device has two rotating members consisting of a rotating member 2 having an anvil 16 and a member 3 rotating in the opposite direction. The rotating member 3 has four cutting blades made of a tough material such as tungsten carbide or tungsten nitride. At least one of the anvil and the tool possesses a low moment of inertia to improve the longevity of the sectioning means.

Abstract: A device comprising an element mounted on the frame 1 and having a microswitch 8 that can be actuated by a mechanical part 9 and which causes the machining current to be cut off when this part 9 arrives opposite it when the machining head 5 moves up.The mechanical part 9 is movable along the guide rod 10 mounted on the machining head 5 and can be fixed at a given height at the start of machining. This height is such that the distance h between the part 9 and the microswitch 8 is less than the distance H between the surface of the workpiece 4 and the level of the machining liquid.The part 9 moves as one with the machining head 5.

Abstract: An EDM machine with a travelling wire electrode having a device for straightening and rethreading the wire electrode. The device has a pivotally rotating arm that has a clamp to grasp the free end of the wire after accidental breakage. The clamp applies a tightening stress (optionally the wire is being heated), the wire portion to be discarded is wound on a capstan (configured with circumferential grooves) associated with the clamp on the arm, a wire cutter severs the wire above the capstan, and finally the wire is rethreaded.

Abstract: Machine for cutting by electrical discharge machining includes an electrode wire tensioned between and running betwee two guide heads each of which is mounted on an arm, one at least of the arms passing through a hole in one of the walls of a tank. The tank can move with respect to the arm and contains a machining liquid. A sealing plate 1 masks the hole in the tank and is linked by at least one seal 4 to the arm 5 through the wall. The wall 2 of the tank through which the arm passes slides along this plate. To prevent the forces due to friction and pressure arising between the plate 1 and the wall 2 and between the seal 4 and the arm 5 and acting asymmetrically on the arm through the wall being transmitted to the arm 5 and causing its deflection, a sheath 6 is mounted between the seal 4 and the arm 5 and encloses this arm without coming into contact with it.

Abstract: A device permits fastening a tool (preferably an EDM tool) to a machining head in at least two different orientations. The tool is mounted on a tool holder, and a pair of portions alternately fix the holder to the head in two different orientations, for example, one in which the tool is positioned for machining operations, and another in which it is positioned for touching up. In a first embodiment the portions are formed as two studs provided on the holder each engageable with the machining head. The studs are positioned with respect to the tool so that engagement with the machining head presents the tool in the two different orientations. In a second embodiment one of the portions is formed on a first tool holder which carries the tool thereon, while the other portion is formed on a second holder mountable to the machining head, the first holder being being mountable either to the machining head directly or to the second holder.

Abstract: An electrical discharge machining fluid consisting principally of de-ionized water and a triethanolamine salt, the latter being at a concentration of 0.2% to 10% by volume.The method for preparing the machining fluid consists in adding to the de-ionized water, under vigorous stirring, from 0.2% to 10% by volume of a mixture of triethanolamine and a fatty acid. The machining fluid of the invention permits to operate at an increased machining speed and to obtain clean machined surfaces.

Abstract: A device for machining by electroerosion has a tool electrode driven in a rotary motion controlled by a servomotor and showing the shape of a solid of revolution around its axis of rotation. A measuring circuit continuously evaluates the degree of contamination of the machining dielectric liquid in relation to a reference value. The measurement is made by a transducer for the instantaneous voltage U.sub.i of each spark and by comparing it to a predetermined value U.sub.b, thus determining the proportion of so-called low-level sparks for which U.sub.i .ltoreq.U.sub.b, a signal being delivered when this proportion surpasses a predetermined threshold, or by a current transductor working during the waiting time preceding the striking of each spark, a signal being delivered when a predetermined current threshold is attained. A servo circuit modulates the rotation speed of the tool electrode as a function of this signal. The detector makes it possible to detect and remedy the appearance of ejected sparks.

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: Device placed at the outlet of a machining zone and having an outflow gauge equipped with two barrels in which a metal wire passes, an electrical current running through the wire which travels under tension between two guides, a pumping installation injecting a machining fluid under pressure through an opening of this guage, an element mounted at another opening of the gauge to measure the outflow of this fluid between wire and barrel, a transducer converting this measurement into an electrical variable, and a comparator suitable for sending a signal to a control unit when this measurement reaches or surpasses a reference value. The control unit is arranged for controlling a pulse generator to change at least one machining parameter in such a way as to bring the measurement of the outflow to or to below the reference value. This device is useful for monitoring the variation in the cross-section of the wire and preventing its breaking.

Abstract: An electro-erosion machine for automatic completion of a cutout according to a closed trajectory or whose ends reach the edges of a part to be machined, or for completing a hollowing by means of piercing the part to be machined all the way through, as well as separating, at a certain predetermined machining moment, a clipping still retained by a narrow bridge of material, said machine being fitted with a numerical control device and at least one machining head, as well as with an auxiliary device, designed to break the bridge which retains the clipping, said clipping being of any shape, and to drop or eject said clipping, the separating being accomplished either by percussion or by exerting a pressure on it, or by shearing the bridge or exerting a torsion-tearing couple on it, or by submitting it to a thermal effect or by localized radiation of the bridge. It can also include an attachment for receiving and automatically evacuating the clipping expelled in this manner.

Abstract: The device has a case (1) which has a wire guide (2) and a chamber (4) filled with machining liquid which is brought there under pressure by a pipe (7). A nozzle (5) in the shape of a truncated cone fits in the case and closes the chamber (4) in its normal working position by supporting its periphery on the flange (6) provided around the case (1), under the action of the pressure exerted by the dielectric liquid and if necessary by a return spring (8). The thrust exerted on the nozzle by an obstacle (10) during a lateral collision tilts the nozzle without damaging it and it causes at L an escape of liquid which causes the pressure to drop in the chamber (4). A transducer (13) signals the drop in pressure following the collision to the operator and/or to a control system of the erosion machine.

Abstract: A method and apparatus for automatically rethreading the electrode wire of a traveling wire EDM apparatus through a pair of close tolerance wire support and guide members, one disposed on one side of a workpiece and the other on the other side of the workpiece, and for threading the end of the wire through a starting aperture in the workpiece. Prior to threading or rethreading the wire, the wire is heated in a heating zone while a pull is exerted on the wire such as to elongate the heated portion of the wire to reduce its diameter. After cutting off the wire at the beginning of its reduced diameter portion, the reduced diameter portion of the wire is threaded through the wire guide members and the aperture in the workpiece. The threading of the wire is effected by a feed mechanism disposed upstream of the first wire guide member which preferably is the same mechanism as the brake mechanism effecting a pull on the wire during normal operation of the EDM apparatus.

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: 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 having orientable swivelling wire guide and support members, or wire guide heads, the orientation of each wire guide head is effected by a pair of hydraulic slave cylinders each connected to a master cylinder. Each master cylinder has an input member displaceable along one direction and the desire inclination of each wire guide head is the resultant of the composite motions of the output members of the corresponding slave cylinders.

Abstract: An EDM device includes two support bars bearing on the same reference surfaces as the workpiece. Gibs are provided which engage into driving units able to displace them axially while holding them at a small distance under one support bar. The other support bar carries the receiving units wherein the gibs engage at the end of their stroke. Each driving unit may push the gib engaged therein against the lower surface of the respective bar. Whenever one or several such gibs are stopped under a part cut out of the workpiece, the part will lie thereon and remains fixed even after the electrode has completed a closed path cutout by electroerosion separating the cut-out part from the workpiece. The cut-out part may then be automatically removed by means of a mobile member equipped with a suction cup.

Abstract: A device installed on a traveling wire EDM apparatus for straightening the electrode wire and providing the electrode wire with a needle point end for facilitating manual threading of the electrode wire through close tolerance closed wire guide members. The device takes the form of a pair of spaced-apart current conductive metallic studs, a heat shield being located at some intermediate portion between the metallic studs. The metallic studs are connected across a source of electrical power. A length of wire proximate its end is held manually over the metallic studs, with an intermediate portion of the wire disposed within the heat shield, and a pull is manually exerted on the wire beyond the metallic studs while the wire is being heated by electrical current flow through the wire between the two metallic studs. The wire is heat-straightened and ruptures at its portion within the heat shield, with sharp needle point ends being formed at the point of rupture.

Abstract: A method and apparatus for holding an electrically conductive workpiece in a machine tool by forming at least one positioning cavity or recess on a face of the workpiece by a holder having a tip used for machining the cavity or recess by a conventional EDM sinking operation. Subsequently to forming the cavity, the tip is used as one of the holding members for the workpiece. Two tips may be used to sink cavities or recesses on opposite surfaces of the workpiece, or the tips may take the form of fingers sunk into the workpiece from one side only. The tips form part of support members mounted on the end of displaceable arms for enabling the workpiece to be positioned relative to a tool or to be displaced. The tip-provided supports may be used for supporting a portion of the workpiece being cut off or severed from the workpiece.

Abstract: A contact device for an electrical current supply of an electrode wire operating in an electro-erosion machine having an electrical conducting part, mounted in free rotation and solidly attached to a shaft extending perpendicularly to the plane of rotation. The shaft is, preferably, also conducting and extends through a leakproof cavity, containing a conductive fluid, such as mercury for example. The conducting part is preferably a steel roller, provided either with a V-shaped groove on its periphery, or animated with a back and forth movement parallel at its axis of rotation.

Abstract: An EDM apparatus having a first support member for the workpiece and a second support member for the guide members of an electrode wire. A cross-slide provides relative linear motions between the two support members for effecting a cut in the workpiece by the electrode wire. A third support member carrying a form electrode tool is arranged to be selectively held stationary either relative to the first support member, by an appropriate first coupling member, or relative to the second support member, by a second coupling member. Under the first condition, the cross-slide provides the necessary relative linear displacements between the electrode wire and the form electrode tool for cutting the electrode tool by the electrode wire and, under the second condition, the same cross-slide provides the necessary displacements for sinking the electrode tool into the workpiece.