Patent GB-1031491-A (GB)
Title: Electrolytic plating
Inventor: SPAULDING ROBERT ALLEN
IPC: B65G49/04
Filed: 1964-02-24
Abstract: <PICT:1031491/C6-C7/1> <PICT:1031491/C6-C7/2> <PICT:1031491/C6-C7/3> <PICT:1031491/C6-C7/4> In electroplating workpieces, each workpiece is mounted on a conveyor and is halted at successive work stations, at least one of which is an electroplating station, and at each work station a treatment liquid is supplied to and removed from a cell which encloses the workpiece.  Typically car bumpers are subjected at spaced stations to a succession of treatments as indicated in Fig. 18 for applying successive electroplatings of flash and coating layers of cyanide copper (stations 9, 10), semi-bright nickel (station 18), bright nickel (station 19), and two chromium layers (stations 25, 27), preferably to produce finely cracked chromium. If desired the bright nickel bath may be omitted or both nickel baths may be the same.  As shown, the bumpers are clamped on appropriately moulded insulating plastic supports 210 formed over castings 186 carried on pallets 118, spring electrical contact fingers extending out of the support engage the work.  The pallets are moved intermittently from the loading point (station 1) to the unloading or exit position (station 32) by a conveyer system comprising idle support rollers 105 and two pairs of transfer rods 477,479 and 478,480. Rods 480,478 carry at the station interval, at positions corresponding in the rest position shown at the left of Fig. 18 to all the stations except stations 16 to 20, 32, pairs of dogs 568, 569 and 570, 571 respectively and single dogs 568 and 571 at stations 16 and 20, while rods 477, 479 carry at stations 16 to 19 only single dogs 573 or 572. The transfer rods are driven by a carriage 474 powered by a hydraulic cylinder 476; rods 478, 480 being fixed to the carriage which also bears a pair of laterally spaced pinions engaging fixed racks secured to the machine base; while rods 477, 479 are slidably mounted within the carriage and bear racks which engage the pinions on the carriage so that rods 477, 479 move twice as far as rods 478, 480.  A double-acting cylinder 520 on the carriage is provided to rotate the rods successively to the various positions shown in Fig. 19 to bring the dogs into and out of engagement with transversely slotted transfer blocks 271, 272, 273, 274 on the base plate 254 of each pallet.  The sequence of operation commences with the dogs in the positions shown at the top Fig 19. Operation of cylinder 520 then causes engagement of dogs 568, 571 with the transfer blocks and operation of cylinder 476 then moves the pallet system from the state of the left hand array in Fig. 18 to that of the next array.  Return operation of cylinder 520 then allows return movement of the rods and operation of cylinder 520 in the opposite direction causes the dogs on both pairs of rods to cause movement on the next operation of cylinder 476 of the appropriate pallets from the right centre array positions to the right hand array positions of Fig. 18.  The sequence of operation proceeds automatically under control of limit switches controlled by the conveyor movements and continues as long as a fresh pallet is introduced into the loading point to keep an "on-station" switch closed.  To provide other sequences of pallet movements a further pair of transfer rods may be provided and different arrangements of dogs which are removable from the rods may be used. When pallets arrive at the electrolytic stations 3, 6, 9, 10, 13, 18, 19, 25, 27, a housing 114 (Figs. 5, 13 not shown) at each such station containing electrode structures 166 having surfaces 167 conforming to the workpiece contour are lowered down over the pallets, sealing gaskets 217, 130 being provided between the housing and pallet and the upper electrode and a run surrounding the workpiece holder, the roller frame 66 also being lowered so that the pallet too is lowered to make senling connections with liquid supply and drain hosss connected to a supply tank such as 89, 90, 91 and pumps 92, 93, 94.  A supplementary electrolyte supply may also be furnished via the upper electrode housing.  The upper electrodes which are anodes except at the acid electropolishing station 6 are of cast-rion for the alkaline cleaning and cyanide copper baths, of cast iron sprayed-coated with lead for the acid polishing and nickel baths, and of aluminium spray-coated with lead for the chromium baths. Electrolyte regenerating tanks may be connected to the solution tanks.  For the cyanide copper bath regeneration is effected by addition of cyanide and hydroxide and anodic dissolution in a cell having a porous diaphragm between anode and cathode.  At the non-electrolytic liquid treatment stations, there is lowered over the pallet a housing containing spray heads (Fig. 4 not shown) while the pallet overlies a drain unit, the treatment liquid from stations 2, 4, 11, 15, 23, 26, 28 being returned to the supply tank while rinse water from stations 5, 7, 8, 12, 14, 16, 21, 22, 24, 29 are let to a main drain.  Ventilation exhaust ducts as 446, 447 (Fig. 4) may be provided at each work station.