GB1086065A - Improvements relating to web feeding devices - Google Patents

Abstract

1,086,065. Feeding webs. MOLINS ORGANISATION Ltd., H. A. STONE, M. A. PYM, and J. W. CZOCH. May 20, 1965 [July 20, 1964], No. 29481/64. Heading B6B. [Also in Division G3] A web feeding and splicing mechanism comprises a container 1, Fig. 1, in which a reserve of running web 2 can be accumulated prior to splicing, a variable speed servo motor 13, Fig. 3, which drives roller 11 of a pair of nip rollers 11, 12, and splicing means which includes a diamond in pregnated surface 28 attached to a pivoted arm 26 and a stationary surface 23 made of a resilient material. The running web 2 is fed from a web-roll 3 and through the splicing means and a guide 21 before being fed into the container 1 by the nip rollers 11, 12. During normal feeding, the web is immediately fed from the container 1 over the lip 62, and a tension detecting pin 60 mounted on a pivoted arm 65 rest in the bight of the web in the container. The pivot pin 66 of the arm 65 controls the output of a variable reluctance bridge type angular displacement pick-off 69, Fig. 3, via gearing 67 and 68. A spring-biased pivoted arm 41 runs on the surface of the web-roll and operates two microswitches 52 and 54 in turn when the arm takes up the respective positions indicated by broken lines 55 and 56. The arm 41 may be held away from the surface of the web-roll by a permanent magnet 45. The web splicing means further includes a spring-biased pivoted cranked arm 19 which carries a cam follower roller 29 to cooperate with a cam 32. Control system.-The two-phase induction type servo motor 13, Fig. 3, has power supplied from an A.C. voltage supply via a silicon controlled rectifier 72 which is triggered to switch on the A.C. at a phase which varies in accordance with an error signal. The latter comprises a coarse control signal obtained by differencing the outputs of tachometers 92 (driven by the web fed machine, e.g. a continuous rod cigarette machine) and 106 coupled to the motor 13. This voltage difference is combined with a sawtooth voltage from the generator 85, 87 to vary the instant at which the combined voltage strikes the silicon controlled rectifier 72. A fine control is obtained from the pick-off 69 which operates in accordance with the position of the pin 60 to produce via a phasesensitive detector 117, 118 a further error voltage for superimposing on the coarse control error voltage. When the diameter of the webroll 3 is sufficiently decreased for the detector arm 41 to reach the position indicated by broken line 55, switch 52 is closed to shortcircuit summing resistor 98. This increases the signal to amplifiers 88 and 89 causing motor 13 to increase in speed and feed an excess of web into the container 1. The detector pin 60 drops to the bottom of slot 64 thereby reducing the signal from pick-off 69 to a minimum switch 52 also completes a circuit to a warning light 57, Fig. 4 (not shown), to indicate that the splicing operation is impending. Switch 52 also completes a circuit to a warning light 57, Fig. 4 (not shown), to indicate that the splicing operation is imminent. When the arm 41 reaches the broken line 56 position, switch 54 closes and corrects the imput of the amplifier to the negative supply of 12 volts causing motor 13 to stop. Closing switch 54 also switches on the cam motor 34, Fig. 4 (not shown), causing cams 32, 35 and 36 to rotate. The pivoted arm 26 moves downward under the control of camfollower 29, whereby the replacement web 4 is cut between knife 24 and counter-knife 7 while the impact of the diamond impregnated surface 28 against the surface 23 causes the cut end of web 4 to adhere to the circuit web 2. At the same time, the web 2 is brought into contact with a knife 20 which is exposed to the web as the guide roller 18 attached to the cranked arm 19 is lowered. As the cams continue to rotate, switch 38 is closed to start the motor 13. Not until the container 1 is empty, and the sensing pin 60 starts to rise is the supply of web brought up to match the demand. As soon as the motor 13 starts, the old web 2 is severed by the knife 20. Further rotation of the cam 36 operates switch 40 to switch off the cam motor 34. When the arm 41 is pushed down to be retained by the magnet 45, the cam motor 34 is caused to rotate a further 20 degrees so as to bring the cams 32, 35 and 36 into their starting positions.