GB1021447A - Improvements in or relating to electrolytic shaping and cavity sinking apparatus - Google Patents

Abstract

Electrolytic shaping and cavity sinking apparatus comprises an axially movable power driven ram carrying a shaping electrode extending into the work area adjacent to an electrolyte chamber at one end and conduits to supply electrolyte under pressure to this chamber from the remote end of the ram together with current-carrying members for said electrode extending from the remote end of the ram so that the work area is free of current and electrolyte supply connections. As shown, the ram 26 comprises a hollow casting of square cross-section slidably mounted on bearings 34 in a housing 22 and driven by a lead screw 40 powered by a rapid transverse motor 58 and a variable speed machining drive motor 56. On the forward end 32 of the ram and insulated from it by a plate of nylon or epoxy resin an electrolyte chamber 68 is attached including a mounting plate 36 for a hollow electrode 38, two current-carrying rods 82 being secured to the chamber wall 66 into which are screwed the ends of two electrolyte <PICT:1021447/C6-C7/1> <PICT:1021447/C6-C7/2> conduits 70, all supported by but insulated from the ram at the far end by resin-bonded glass fibre mounting members 74, 75. Currents of up to 8000 amps./sq. inch may be employed. To protect the ram from electrolyte splash, a stainless steel guard plate 98 coated with an epoxy or other insulating resin is connected by a chlorinated synthetic rubber bellows 96 to an electrolyte chamber surround 94 of metal coated with epoxy resin. A flexible non-conducting hose 78 joins the pipes 70 to a pump-fed supply pipe 81. Electrolyte pressures of up to 300 lbs./sq. inch may be used. The work-holder (not shown) is connected to the positive grounded side of a D.C. supply and the ram and its housing are also grounded, the electrode 38, chamber 68 and rods 82 being negative. In an alternative form for an electrolytic lathe, Figs. 6-11 (not shown), the ram comprises two rods slidably supported in a fixed block through apertures in which pass the current-carrying rods and electrical conduits. A nylon or epoxy resin section may be included in the conduits and outside the ram housing below a non-conductive flange there may be arranged a sacrificial section of pipe lined with graphite and grounded. The work area is surrounded by a stainless steel housing adjoining the ram as at 98 in Fig. 4 and through a lubricated fixed seal in which extends a work-holder mounted on a driven shaft to which electrical connection is made by brushes. A modified form of the construction of Fig. 4 in which insulation in the ram is avoided, the ram and housing and the base plate for the work-holder all being connected to the negative grounded side of the supply, is shown in Fig. 13, the work-holder being insulated from the base by an epoxy resin bonded glass cloth laminated pad 318. The electrode 322 is solid and extends into an epoxy resin bushing 324 into which electrolyte is fed by a hose 330 from the electrolyte chamber, a vent 332 also being provided. Compressed air may be fed into the interior of the ram for cooling purposes. Reference is made to employing hollow heavy section copper bus-bars to serve both as current carriers and electrolyte conduits.