Patent GB-558660-A (GB)
Title: Improvements in and relating to tobacco feeding mechanism particularly for cigarette making machines
IPC: C08F2/00
Filed: 1942-06-03
Abstract: 558,660. Automatic control systems. AMERICAN MACHINE & FOUNDRY CO. June 3, 1942, No. 7554. Convention date, June 6, 1941. [Class 38 (iv)] [Also in Groups VI, XXXVI and XL] Means for feeding tobacco to the rear end E of an advancing tobacco layer or column TC is controlled by an electrostatic device to vary the feed of tobacco in accordance with variations in the position of the rear end of the layer or column relative to the electrostatic device, which preferably controls a variable speed transmission by which the feeding means is driven. As shown in Fig. 1, tobacco from a feed drum 13 in a hopper 10 is showered by a picker roll 19 upon a feed plate 21 supported on leaf springs 25 and vibrated by means of an electromagnet 37. A tobacco layer TC formed between the plate 21 and a plate 47 is fed over a concave surface 49 by a roller 53 and a picker roll 55 showers the tobacco through a chute 57 upon the travelling web or cigarette-paper strip P of a continuous rod machine. An electrostatic device adjacent to the rear end E of the tobacco layer TC comprises a pair of condenser plates 63, 65 responsive to variations in capacity due to movement of the rear end E, and connected to a control circuit, Fig. 4, for a motor 352 serving to adjust a variable-speed gear 356 through which the feed drum 13 is driven from a motor 357. The condenser plates 63, 65 are located in recessed non-conducting plates 47, 21 and are supported by studs from brackets 49 adjustable in two directions by bolts 71 engaging slots in the brackets 69 and in the side walls. In a slight modification, brackets such as 69 are provided with pointers moving over scales to indicate the adjustment. The plates 63, 65 are connected, together with a variable and standard condenser 302, between a tuned coil 312 and respective opposite ends of the centre-tapped anode coil 306 of an oscillator valve 307 generating, say, 500 kc/s oscillations, whereby normally equal and opposite currents are produced at the ends of coil 306 and no voltage is impressed on coil 312. In the event of a change of capacity in the plates 63, 65, the resulting voltage across the coil 312 is amplified at 313 and fed through a high-frequency transformer 336, the two-part secondary of which is connected to an indicator tube 316 and also, for separate rectification of the H.F. voltages, to a double-diode 337, the rectified voltages from which are impressed on the grids of output valves 317, 317a adjustably biased by series-connected potentiometers 341, 341a. The valve plates are connected to electromagnets 325, 325a operating on a balanced armature 344 to control the reversible motor 352, which adjusts the variable-speed gear 356. In setting up the system, condenser 302 is adjusted for zero output of the valve 313 with the detector device unoccupied. When the tobacco layer has reached the desired position and the rheostat 330 has been set for maximum amplification, potentiometers 341, 341a are set below the trip points of the valves 317, 317a. When one of the latter is tripped, depending on the sense of the variation, the feed is adjusted to restore the desired average. A cam 343 driven by the mechanism opens a switch 342 to cut off the valve 317 or 317a after a time sufficient for the correction to be detectable betwen the plates 63, 65 and if the correction is insufficient a further correction will be made when the switch 342 recloses. Specification 558,491 is referred to. The Specification as open to inspection under Sect. 91 comprises also a modification of the detector device, the condenser plates are replaced by a feeler plate, pivoted in the upper plate of the feed channel and connected to a bar having rack teeth meshing with a gear acting upon a shaft of a pivoted contact arm which coacts with two contacts in the circuits of a reversible motor such as 352, Fig. 4. This subject-matter does not appear in the Specification as accepted.