GB973422A - - Google Patents

Abstract

973,422. Feeding webs. PORTALS Ltd., and A. J. TOOTH. Aug. 8, 1962 [Aug. 16, 1961], No. 29640/61. Heading B6B. [Also in Division G3] Relates to a longitudinal registering of a web being fed into a processing machine, wherein means are provided for measuring at a sensing station along the web and in relation to the timing of a particular operation in the process, the distance from the sensing station of a mark on the web. In the particular embodiment shown, a web 2 is fed by continuously driven nip rollers 3 to be cut into sheets by a rotary knife 5. The registration apparatus comprises photo-electric means, 13, spaced along the web from the knife at the required nominal sheet length, which produces an electric signal when sensing a mark such as one of a plurality of water marks 6, 7 and 8, spaced along the web also at the required nominal length. The rotary knife 5 is driven through epicyclic gearing 14, a clutch 11, and a variable gear-box 9 by a motor 10, which also drives the nip rollers 3. A rotary switch 12 is provided to give a reference signal once per revolution of the knife 5. A correction motor 15 is connected to drive the planet gear carrier of the epicyclic gear 14 to advance or retard the speed of the knife 5 relative to the nip rollers 3. The epicyclic gear could equally be applied to the nip rollers and give the same result. A correction pulse generator 17, is driven directly by the correction motor 15, and is capable of producing 10,000 or more discrete pulses for one revolution of the knife 5 when the motor 15 is driven at maximum speed (the main motor 10 being stationary). Each pulse therefore represents a small fixed percentage of the nominal sheet length. The generator 17 may be of the type having a rotating transparent disc engraved with opaque radial lines which are sensed by a photo-electric device. An error pulse generator 18, driven by the gear-box 9, produces discrete pulses, each pulse corresponding to the same percentage of the nominal sheet length represented by a correction pulse. Two pulse counters 19, 20, are permanently connected to receive pulses from the error and correction pulse generators respectively. When the machine is operating, a signal from either the switch 12 or the photo-electric device 13, whichever is first, energizes the error counter 19 so that the error pulses are counted. A signal generated from the device 13 or the switch 12, whichever is last, de-energizes the error counter 19 so that it stops counting. At the instant the error counter is de-energized, the correction motor 15 is started, and correction pulses generated are counted by the correction counter 20. A coincidence sensing device 27 connected between the error and correction counters continuously compares the counts stored until coincidence occurs. The device 27 then stops the correction motor 15, since, longitudinal registration is achieved, and resets both counters in preparation for the next sheet. An automatic brake acting on the correction motor 15 may be applied 5 pulses before coincidence occurs, which will prevent over-run.