GB986218A - Improvements in or relating to a method and apparatus for electrolytically removing material from a workpiece - Google Patents

Abstract

In the anodic erosion, using D.C., of material from an electrically conductive workpiece wherein an electrolyte is pumped to and through a work gap between the workpiece and a cathode, the used electrolyte containing insoluble particles formed from eroded workpiece material is recovered for re-use by causing gas to bubble through a body of the used electrolyte to float flocs of the eroded material to the surface of the electrolyte and at least periodically skimming the scum from the surface. As shown, electrolyte such as a common salt solution is pumped at a pressure of 40-250 p.s.i. controlled by valves V2, V1 from a tank 46 along a fixed pipe 42 through a filter F for dirt to a feed hose 30 connected to an injector conduit 28 in an insulating block 22 which is clamped to the workpiece W to define a working area and through which projects a hollow cathode 10 insulated except at its working tip and carried by a ram 12. The electrolyte, eroded material and evolved gas (mainly hydrogen) is removed through the cathode, hose 34 and pipe 62 and passed through a valve V3 so that the stream enters a flotation well 44 open to the air through a perforated T-junction pipe 64 at about 1/3 of the working pressure, say 50-75 p.s.i. This results in flocculant material being carried to the surface while other insoluble material sinks to the bottom of the well. Scum may be raked or blown by air jets from nozzles 70 into a gutter 55 from which its is withdrawn through a valve. If required scum formation may be assisted by bubbling air from line 76 and header 74 through the electrolyte in the well to which household detergents or pine oil may be added. Clear electrolyte between the scum and the bottom settlements passes through pipe 52 into the supply tank 46 to which make-up solution is added from reservoir 66. <PICT:0986218/C6-C7/1>