Abstract: Method and apparatus for accumulating and restituting cold, the apparatus comprising a storage vessel containing a heat-exchanging and cold-accumulating liquid mixed with a mass of rigid aggregates of crystals of frozen liquid, the crystals being obtained by freezing the liquid by atomization of a refrigerating fluid contacted directly by the liquid, means to create during the cold accumulation phase a piston composed of a homogeneous, porous and compact mass of rigid aggregates of crystals of the liquid, means to deposit the crystals evenly on top of the piston, and means to resorb the piston from the top.

Abstract: A method and apparatus for generating, by siphon effect, in a housing containing a cold-accumulating and freezable liquid, a current of liquid in a closed hydraulic circuit, the current of liquid comprising at least one ascending current which is located over means for injecting a refrigerating fluid and which contains bubbles of atomized refrigerating fluid, and at least one descending current free of refrigerating fluid in the gaseous phase.

Abstract: A correction system for a travelling wire EDM machine cutting a workpiece by means of a travelling electrode wire stretched between two guide members and comprising a pair of servo motors for effecting displacement of the guide members relative to their respective support arms, such as to incline the electrode wire relative to the workpiece for providing the cut in the workpiece with an appropriate predetermined conicity or draft. One of the servo motors providing such displacement is, in addition, controlled such as to compensate for thermally-induced expansions or contractions of one of the support arm guide members relative to the other.

Abstract: A metallic wire, for cutting a workpiece by electrical discharge machining, coated with at least one layer of a metal having a low temperature of vaporization and a film of a metal oxide on the metal layer. The metallic coating is preferably made of zinc and is subjected to an oxidizing thermal or electrolytic treatment such as to form on the surface of the metallic layer a thin film of zinc oxide.

Abstract: A method and apparatus for cutting a workpiece by electrical discharges by means of a travelling wire electrode according to a path determined by a numerical control program without reducing the machining speed or the current flowing into the wire electrode. At least one of the support and guiding members of the wire electrode is displaced relative to the workpiece along a path resulting from shifting each point of the desired cutting path a predetermined distance in the direction of machining along a tangent to each point of such path. The angle between the tangent at each point of the path relative to the coordinate axes is determined, and each point of the path is shifted relative to the programmed path along coordinates having values proportional respectively to the sine and cosine of the angle.

Abstract: Process and apparatus for cutting by electrical discharge machining cavities and slots in an electrode workpiece by means of an electrode tool, the electrodes being displaced one relative to the other in translation along a predetermined path. The translation motion is controlled such as to maintain predetermined machining conditions in the machining zone between the electrodes, and for additionally displacing the electrodes relative to each other in a direction different from the direction of the cutting path. The additional relative displacement of the electrode may be linear, non-linear, slanted or curvilinear.

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 method for machining materials difficult to cut by EDM conventional processes and consisting in providing contamination of the machining or dielectric fluid used in the course of electrical discharge machining with particles of a metal or metallic alloy of low vaporization temperature selected, for example, from the group consisting of zinc, cadmium, tin, lead, antimony and bismuth. The contamination particles are obtained directly from a surface coating placed directly on the electrode tool or from an additional piece of metal or metallic alloy which is electro-eroded at the same time as a cut is effected by the electrode tool in an electrode workpiece, and the contaminated fluid is circulated in the machining zone between the electrodes, the contaminated fluid facilitating the triggering of the electrical discharges in the machining zone and providing an increase of the machining rate, or material removal rate.

Abstract: A process and apparatus for controlling the retraction of the electrode tool of an EDM machine such as to maintain the material removal rate to a value approaching the maximum theoretical value. The control system comprises monitoring the machining rate for providing an average value of the material removal rate during at least a time interval corresponding to a single retraction period of the electrode, and varying the frequency of subsequent retractions of the electrode as a function of that average value such as to consistently maintain a material removal rate which is self-adaptive and tends to reach a maximum theoretical value.

Abstract: The present invention is an EDM (Electrical discharge machining) process and apparatus for machining an electrode workpiece by means of an electrode tool wherein the electrodes are displaced relative to each other along a principal feed axis while, simultaneously, the electrodes are displaced relative to each other along an orbital path in a plane perpendicular to the principal feed axis, such as to produce between the electrodes a three-dimensional translation motion, and for providing between the electrodes an average machining gap wider than the gap width sustaining electrical discharges. The invention provides a control of the amplitude of the relative translation motion of the electrodes while displacing the direction of said motion as soon as a predetermined orbiting path limit is reached such as to allow a rapid increase of the gap between the electrodes when the electrode tool is retracted.

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: 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: 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.