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US 4,870,243 AGranted
Electrical discharge methods and apparatus therefor
AssigneeSarclad International Limited
InventorsGeoffrey Wilson, Gareth A. Evans
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AssigneeSarclad International Limited
InventorsGeoffrey Wilson, Gareth A. Evans
Estimating the term…
An electrical discharge apparatus comprises a plurality of electrodes mounted on an electrode carrier and spaced from a workpiece surface to define a gap across which a train of electrical pulses are transmitted. Dielectric fluid is present within the gap and controlled additions of solid particles are made to the dielectric fluid, with the particles being of a material of different electrical conductivity and/or permittivity to that or those of the dielectric fluid. The concentration by volume of the particles within the dielectric fluid lies within the range 0.05% to 7.0% and the size of the majority of the added particles is in excess of 7 microns. The particles are of a material having a relatively high electrical conductivity, e.g., graphite or metallic particles. Alternatively, the particles are formed from a material having good electrical insulating properties, e.g., glass, ceramic or certain metallic oxides.
Electrical discharge apparatus comprising a plurality of electrodes mounted on a carrier and spaced from a workpiece surface to define a gap across which a series of electrical pulses is transmitted and within which a dielectric fluid is present, means for moving the electrode carrier relative to the workpiece surface, and means for making to the dielectric fluid controlled additions of solid particles of a material of different electrical conductivity and/or permittivity to that or those of the dielectric fluid, the concentration by volume of the particles in suspension within the dielectric fluid lying in the range 0.05% to 7.0% and the size of the majority of the added particles in suspension being in excess of 7 microns.
A method of applying a machined or textured finish to the surface of an electrically conductive workpiece, which method comprises effecting relative movement between an electrode carrier including a plurality of electrodes and the workpiece surface, applying across the gap defined between the electrodes and the adjacent workpiece surface a series of discrete electrical discharge thereby to remove particles from the workpiece surface, and supplying to the gap present between the electrodes and the workpiece surface a dielectric fluid in which is dispersed a quantity of particles of a material of different electrical conductivity and/or permittivity to that or those of the dielectric fluid, the concentration by volume of the particles in suspension within the dielectric fluid lying in the range 0.05% to 7.0% and the size of the majority of the particles in suspension being in excess of 7 microns.
Dependencies are inferred from the claim text.