GB785589A - Improvements in or relating to machines for manipulating cut tobacco - Google Patents

Abstract

785,589. Cigarette - making machines. MOLINS, D. W., POWELL, G. F. W., and MOLINS MACHINE CO., Ltd. June 16, 1954 [March 16. 1953], No. 7201/53. Class 130. [Also in Group XXXV] In a machine for manipulating cut tobacco, variations in the mass per unit length of a moving tobacco filler are automatically corrected by an electrical signal, responsive to such variations, which controls the distribution of tobacco on to an endless conveyer whose speed at the delivery end is constant. In a cigarette making machine, Fig. 1, tobacco is showered from a hopper @ to a hopper tape 2 @ succession by @elt @ eyers 4 and 6. Thereafter it passes down a sloping passage 11 as described in Specification 646,746 and is delivered on to a cigarette paper web 12 moved by a garniture tape 13. To effect the long-term correction, the output of a radioactive detector 15, which is dependent on the mass per unit length of the tobacco on tape 13 is applied to an amplifier and feedback filter 16 so as to control, through a variable-speed oil unit 19 a differential gear 23 in the drive between a motor 22 and tape 13. Still longer-term variations are effective through a filter circuit 17 to produce additional correction by controlling, through a relay 21 and a solenoidoperated ratchet device 20, a variable speed pulley 18 in the drive between motor 22 and hopper 1. To effect short-term correction, the output of a further radio detector 5 associated with a short length of the tobacco stream near its point of delivery on to conveyer 6 is applied through a feedback thermionic valve amplifier 24 to control one of a cathode-coupled pair of thermionic valves in a filter stage 25 controlling differential moving coils 67 operating a valve 68 of an hydraulic unit 69 controlling a differential gear 9 in the drive between pulleys 7 and 8 of conveyer 6. Since pulley 8 is directly driven by motor 22 the speed of pulley 7 is thus varied to alter momentarily the rate of supply of tobacco on to belt 6. Although metal teeth (not shown), bonded on to the inner surface of the belt, engage with grooves on pulleys 7 and 8, momentary difference in speed of the pulleys is possible because belt 6 is elastic, being of rubber, plastic or canvas and rubber. The output of a potentiometer 70, operated with differential gear 9, is applied through an integrating circuit to control the other valve in stage 25 in a sense tending to prevent excessive movement of differential gear 9. In a modification, Fig. 6 (not shown), belt 6 runs at constant speed and the point at which tobacco is fed to it is adjusted to effect the short-term correction. An alternative arrangement in which the long-term variations are correction before the short-term variations is referred to. Use of scintillation counters instead of ionization chambers is referred to. Specifications 781,041, [Group XXXV], 781,042, 785,590 and 785,591, [Group XL (a)], also are referred to.