Patent GB-737181-A (GB)
Title: Improvements in or relating to the manufacture of viscose
Inventor: NEWTON THOMAS DAVID
IPC: D01F2/08
Filed: 1952-08-26
Abstract: Apparatus for the manufacture of viscose comprises, in combination with a xanthating churn, such as that described in Specification 737,182, a weighing device for extracting weighed quantities of alkali cellulose crumbs from a stream of such crumbs supplied continuously to it and delivering those weighed quantities in succession to the churn, mechanism for feeding a metered supply of carbon bi-sulphide to the churn, and means controlled by the weighing device for so controlling the feed mechanism that the rate of supply of carbon bi-sulphide to the churn is varied to suit the changes in the rate of supply of crumbs.  As shown in Fig. 1, matured alkali cellulose, which may be produced as described in Specification 707,422, is supplied from a device C to the uppermost compartment a of a rotary segmental hopper 34.  The counterweight 37 is thereby over-balanced, thus causing the beam 35 pivoted on the bracket 36 to rock and thereby to free one of the four projections 38 on the hopper from a fixed stop 39 carried by an extension 40 of the bracket 36. The hopper is thus allowed to rotate clockwise to tip out the alkali cellulose into the compartment b of the upper rotary segmental valve 44 contained in a vertical trunk 41 and to bring the next compartment of the hopper into position for filling.  During the tipping of the alkali cellulose, the counter-weight 37 restores the beam to its initial position, <PICT:0737181/IV (a)/1> with the result that, after one-quarter revolution of the hopper, the next projection thereon coacts with the fixed stop 39 to arrest the hopper.  The upper and lower rotary segmental valves 44 and 45 each have four compartments and are a close fit in correspondingly-shaped housings in the trunk 41; thus they constitute, with the trunk 41, a trap to prevent escape of carbon bisulphide vapour from the inlet end of the churn F.  Any carbon bi-sulphide vapour leaking past the lower rotary valve 45 is removed through the vacuum connection 46 provided in the trunk 41 between the rotary valves 44 and 45.  These valves are periodically rotated through one-quarter revolution by means of an electric motor 47, fitted with an electromagnetic band-brake BR1 and driving, via gear-box 48, gear-wheel 49, and gear-wheel 50 on the lower valve 45, and via idler gear 52 and gear-wheel 51 on the upper valve 44.  When the beam 35 is tipped by discharge of alkali cellulose into the compartment a of the hopper 34, the micro-switch MS1 is closed and, by means of an automatic electrical control system, supplies current to the motor 47 driving the rotary valves 44, 45.  After these valves have turned through one-quarter of a revolution, the next point of a four-point cam 53 actuates a micro-switch MS2 and thereby stops the motor 47 and prevents it from over-running by means of the electro-magnetic band-brake BR1.  The rotation of the valves 44, 45 and consequent periodic actuation of the micro-switch MS2 by means of the cam 53 causes current to be automatically supplied to an electric motor 55 actuating a pump 54 to squirt into the fixed inlet pipe 42 of the churn F a quantity of carbon bi-sulphide appropriate to the charge of alkali cellulose delivered into the inlet pipe 42 at each one-quarter revolution of the lower valve 45.  After a predetermined time delay, the motor 56 is started and the motor 55 is stopped.  The motor 56 drives a disc fly-wheel 57 carrying a crank-pin 58 for imparting reciprocating movement to a ram 43 by means of a connecting-rod 59, and the ram 43, when moving from right to left in the inlet tube 42, discharges into the churn F the mixture of carbon bisulphide with the alkali cellulose previously discharged into the tube 42 by rotation of the valve 45 through one-quarter revolution. When the ram 43 has completed its return stroke the microswitch MS3 is actuated and discontinues the supply of electricity to the ram motor 56, which is prevented from over-running by its brake BR2.  The cycle of operations is then restarted by re-closure of the switch MS1 by the beam 35.  Specifications 700,693, 707,442, [Group XXXVII], and 737,185 also are referred to.