Patent GB-914150-A (GB)
Title: Improvements in or relating to the splicing of preprinted webs
Inventor: ASTLEY EDWARD THOMAS
IPC: B65H19/16
Filed: 1960-07-04
Abstract: 914,150. Feeding webs. CROSFIELD ELECTRONICS Ltd. July 3, 1961 [July 4, 1960], No. 23294/60. Class 100 (1). [Also in Group XL (b)] Apparatus, Fig. 1, for sticking a moving web of paper 1, carrying a repeated pattern from an expiring reel 2 to a new rotating reel 3 of paper carrying a corresponding pattern comprises control means 10, 16 responsive to photo-electric means 6, 8 sensing register marks 5, 7 on the two webs and operative to actuate sticking means 17 when the interval between the photoelectric cell signal indicates that the patterns on the attached webs will be substantially in register, means 23-25 operable to vary the relative speed of the web and the new reel being provided and further means being provided to prevent the operation of the speed-varying means until a predetermined time has passed since the commencement of a search for an in-register condition of the web and reel without operation of the sticking means. The invention is based on the principle that the relative register of the two webs will change on each reel revolution by an amount determined by the reel circumference and the length of the repeated pattern and that the two webs will consequently come into register in time, of their own account, without requiring any speed control. However, if no such correspondence is obtained after, say, twenty-three revolutions of the new reel, it is evident either that the change of register between the two webs is inconveniently slow, or the new reel has a circumference equal to an exact number of patterns and its peripheral speed exactly equals that of the expiring web so that no change of register is taking place. In that event the speed-varying means is operated and the speed of the new reel is altered by, for example, one per cent, so as to increase the speed of, or bring about, a register change. If a point of good register is still not obtained, means may be provided for stopping the machine before the web of the expiring reel is completely exhausted. As illustrated, the speed change is brought about by a motor 23 which applies a correction through differential gearing 24 to the main driving-shaft 25. Alternatively, an electromagnetic clutch in the main drive may be momentarily de-energized. The search for an in-register condition may be initiated either by actuation of manual means 30 or by photoelectric means measuring the diameter of the expiring web. In the apparatus for determining the in-register condition, Fig. 2, the impulses from the photo-electric reel scanners 6 and 8 are applied through respective amplifiers 11 and 12, the first to develop, by means of circuits 21 and 22, a voltage proportional to the speed of the expiring web, and the second to trigger a gate pulse generator 13. The voltage from circuit 22 controls generator 13 so that the pulses are inversely proportional to the speed of the expiring web and thus represent a certain length of paper. The pulses control a gate 14 and if a pulse from amplifier 11 is received within the time occupied by a gating pulse the register is sufficiently good for a paste to be made and an output signal is applied to actuate a paste trigger circuit which controls sticking means 17, Fig. 1, and subsequently operates a knife (not shown) to cut the expiring web. A counter integrator responds to the pulses from gate 13 and produces a signal to actuate the speed-varying means 16 if an in-register condition is not detected within a predetermined time. To allow for the operate time of the sticking mechanism, the register mark 7 may be displaced around reel 3 or an equivalent effect may be introduced by electronic delay means. Specification 797,527 is referred to.