GB1405563A - Electrochemical machining - Google Patents

Abstract

1405563 Electro-chemical machining holes TRW Inc 30 Nov 1973 55715/73 Heading C7B Material is electrolytically removed from a workpiece 24 without penetrating with a tool by flowing an electrolyte through a dielectric material (e.g. boro-silicate glass) nozzle 20c to impinge as a jet 21 against the workpiece surface 24a, maintaining a fixed gap between the nozzle tip end 20d and the surface, e.g. by providing a glass rod 22 centrally in the nozzle tube 20 using washers or collars 23 to project beyond the tip end and bottom against the surface, applying a potential to cathodically charge the electrolyte in an enlarged zone upstream from the nozzle, e.g. in header (30) Fig. 10 (not shown), provided with electrode (Ti, Pt, Ni, or W wire 41) common to a plurality of nozzles (10), and simultaneously anodically charge the workpiece, controlling the potential and jet flow-rate to remove material from the workpiece (e.g. of alloy steel, Ni, WC, W, Mo, Ti, V, Cr, alloy thereof or Fe) only at the area of impingement of the jet, including maintaining a relatively low potential until a stream directing dimple is formed in the workpiece, then increasing the potential as the cavity deepens until a hole is formed through the workpiece, and then increasing the potential to straighten the hole bore. As shown a large cylindrical hole 25 may be cut leaving a central core 26, but a plurality of small holes (63, 64, 65) Fig. 11 (not shown), may be drilled into jet engine nozzle blades (60). The electrolyte may comprise sulphuric, hydrochloric, nitric or citric acid.