GB1064372A - Automatic machine for piercing and feeding baths for fusion electrolysis - Google Patents

Abstract

1,064,372. Agitating furnace charges; charging electrolytic furnaces. PECHINEY COMPAGNIE DE PRODUITS CHIMIQUES ET ELECTROMETALLURGIQUES. Sept. 24, 1964 [Sept. 24, 1963], No. 39010/64. Heading F4B. An automatic machine for piercing crusts on and feeding alumina to baths for fusion electrolysis comprises a support carriage displaceable in front of the baths, a fluid-operated jack carrying a fluidoperated piercing hammer, an alumina hopper with discharge member operating behind the hammer, and a sequence mechanism controlled by a time switch and positioning members producing the following operations :- (1) refilling the buffer, (2) moving the machine opposite an anode, (3) piercing the crust at a number of points, (4) discharging alumina over the pierced area, (5) repeating the above at a number of anodes, and (6) returning the machine to the starting point. The machine support frame 110 mounted on upper wheels 121, 122 and lower wheels 111 carries winches 210 and 220 respectively supporting a flexible compressed air pipe and an electric cable, the pneumatic hammer assembly 300, the hopper assembly 400, and the sequence control assembly 500. The hammer assembly comprises a pick 306 sliding in the hammer head 301, the length of stroke being indicated by a detent 308 engaging a stop 309, and a doubleacting jack 312 vertically movable about its piston 313, the piston-rod 311 being attached at 302 by a universal joint to the support frame and movable horizontally to vary the piercing position by a pneumatic jack 320. Energization of an electrically-operated valve 332 introduces air to the full face of piston 313 moving jack 312 downwards and at the same time closing an obturator 305 above the pick-rod 307. When the pick strikes a crust, the obturator 305 is opened, allowing compressed air in the space 303 to operate the pick. Vertical movement of the jack 312 is controlled by stops 516, 517 engaging a contact 533. Swinging movement of the jack 312 is induced by the double-acting pneumatic jack 320 controlled by electricallyoperated valve 333. This movement is guided by arms 341, 342 articulated to the hammer and to a plate 343 attached to straps 344 articulated to the upper frame 120. The jack 320 is articulated to straps 344 at 346 in series with a double-bodied jack 350, Fig. 7 (not shown), by which a plurality of piercing points are obtained in line. The hopper assembly 400 comprises a feed hopper 410, a deformable diaphragm valve 420 and a delivery hopper 431 having a discharge flap 432 operated by a pneumatic jack 433 controlled by the electrically-operated valve 423. When the latter is energized, compressed air from the system 331 closes valve 420 and operates jack 433 to open flap 432 delivering a measured quantity of Al 2 O 3 . Air passing through a porous slab 413 encourages movement of the Al 2 O 3 in the bottom of feed hopper 410 which is fed from a silo 447, Fig. 6 (not shown). When the feed hopper is full, a small motor driven fan 416 is slowed down closing a relay controlling a valve to arrest the flow of Al 2 O 3 . The sequence control assembly 500 comprises proximity detectors supplying input signals mounted on the machine and energizing members mounted on the series of baths, Fig. 9 (not shown). The detectors are :- (1) detectors of the position of the machine relative to the series; DPA ref. 511 and DPB ref. 512; (2) detectors of the position of the machine relative to a bath; DPC ref. 513 and DPD ref. 514; (3) detector of the position of the machine with a view to piercing in case of preburning; DPE ref 515; (4) detectors of the position of the piercing hammer; DPH ref. 516 (raised) and DPI ref. 517 (lowered); (5) the detector responsible for stopping the supply of Al 2 O 3 to a bath; DPF ref. 518. The energizing members are :- (1) plates 521 for energizing DPA 511 and DPB 512 when the machine is at the end of the series; (2) plate 522 for energizing DPA 511 when the machine is in position for piercing at the end of a bath; (3) plate 523 for energizing DPB when the machine is at the beginning of a series; (4) winding 524 for energizing DPE 515 at the beginning of a piercing operation in the case of preburning; (5) seven plates 525-531 including a retractable plate 526 for energizing DPC and DPD simultaneously in pairs when the machine is in position in front of an anode to initiate piercing; (6) retractable plate 532 energizing DPF to inhibit feeding of a bath with Al 2 O 3 ; (7) plate 533 energizing DPH 516 when the piercing hammer is raised and DPI 517 when the hammer is lowered. The input signals emitted by the detectors control the machine through a known interlocked signalling memory-storing system, Figs. 11-25 (not shown). The working of this system depends on the programme imposed on the machine, and enables the following automatic operations:- (1) discontinuous preventive piercing (A programme); (2) continuous piercing (B programme); (3) piercing for burning unpacking or preburning unpacking (C programme); (4) feeding with Al 2 O 3 after each piercing cycle.