Patent GB-324895-A (GB)
Title: Improvements in and relating to feeding devices for webs of paper and other material
IPC: B65H23/188
Filed: 1928-10-04
Abstract: 324,895. Boothroyd, A., and Knowlson, J. M. Oct. 4, 1928. Feeding and registering webs.-Relates to the method of correcting errors or register in feeding a previously marked or printed web to a cutting, printing, perforating, folding, or other device, in which perforations in the web co-operate with a detector to close an electric circuit to retard or accelerate the web relatively to the cutting &c. device if a perforation arrives at the detector early or late with respect to the disposition of an element moving in synchronism with the cutting &c. device or the web-feeding device, and consists in maintaining the electric circuit operating the web retarding or accelerating device until an error of register in the opposite direction is detected. Any suitable device may be employed to vary the speed of the web relatively to the cutting &c. device. As shown in Fig. 2, the web in a bag-making or other machine is fed by rollers 6 to a cutter 12 and guide rollers 7. The cutter is geared to the rollers 7 by spur and bevel gearing 13, 14 and the rollers 6. 7 are connected by a belt 8 engaging cone pulley discs 9 adjustable to vary the speed of the rollers 6 by a motor 10 and pivoted levers 11. In another form, Fig. 4, the rollers 6. 7 are connected by a belt 16 and cone pulleys 15, the belt being initially adjusted by a hand-wheel 17 so that the speed of the web is slightly above or below the normal. The pulley 15 is secured to a sleeve 20. Fig. 5, loose on the shaft of the roller 6 and connected by reducing or step-up gearing 21, 22, 22a to a gear 23 fast on the shaft, and the gears 22, 22a are carried by a drum 19 with which cooperates an electromagnetically operated brake 18. This brake is applied when the error of register of the web exceeds a certain amount so that the speed of the web is reduced or increased. The belt 16 may be set for normal web speed and two brake drums 19, 25, Fig. 5, one provided with a reducing gear train and the other with a step-up gearing may be provided. One form of control for the electromagnetic brakes is shown in Fig. 11. The web passes over a conducting roller 5 with which co-operate a pair of detector brushes 26, 29 connected to the windings 46, 45 of a standard form of polarized relay 40, the tongue 43 of which is adapted to close a circuit through either of the magnets 47, 48 of the speed-regulating devices. A third brush 28 contacting with the roller 5 is connected to one of a pair of contacts 33 co-operating with a segment 32 of a timing switch 30 rotated in synchronism with the cutting device. The other contact 33 is connected to the magnets 47, 48. The arrangement is such that if the perforations in the web are in advance of or behind their correct position when the contacts 33 are shortcircuited by the switch 30, a circuit is completed through the brush 26 or 29 and the corresponding magnet 48, 47 to retard or accelerate the web. Instead of the form of relay 40 shown in Fig. 11, a relay of the type having locking windings 62, Fig. 12, may be employed. In a further form, the magnets 47, 48 are not connected directly to the relay 40 but are connected to switching relays controlled by the relay 40 and adapted to actuate heavier current carrying contacts. If the web speed is initially set to be slightly above or below the correct speed, a single brush 26 or 29 and a single controlling magnet 48 or 47 only are required, one of the contacts of the relay tongue 43 being an idle one. In the arrangement shown in Fig. 15, the timing switch 30 cooperates with three contacts 33 the central one of which is connected to a detector brush 26 and the outer ones to a split battery 58 connected to the grid of a thermionic device 59, the plate circuit of which contains the coil 55 of a relay. The tongue 56 of this relay is normally held by a spring 57 against a contact 56a so that the switching relay coil 51 is energized and its contacts 50 closed to energize the magnet 47 and thus accelerate the web. When the error of advance of the web is such that the brush 26 makes contact through the perforations with the roller 5 while the switch 30 short-circuits the central contact 33 and the contact connected to the negative side of the battery 58, positive potential impulses are applied to the grid thereby energizing the coil 55 and moving the tongue 56 into contact with the contact 56b. The magnet 47 is thus de-energized and the magnet 48 energized through its relay 51 to cause a retardation of the web until negative impulses are applied to the grid due to the short-circuiting of the central contact 33 and the contact connected to the positive side of the battery 58. Fig. 16 shows an arrangement in which a selenium cell 70 is employed. A shutter 72 driven in synchronism with the cutting device cuts off the light passing from a source 71 through the perforations when the latter are in the correct position. The web speed is normally set to be slightly above normal. When the resulting error is above a predeter mined amount light falls on the cell 70 and current flows through a relay coil 45 to close a contact 69 and thus energize a magnet 73 which produces a retardation of the web speed. When the web is so far retarded that an error in the opposite direction occurs a switch 74 is opened by a cam actuated by a moving part of the machine to de-energize the magnet 73. The switch 74 is allowed to close by a spring when the shutter 72 again synchronizes with the perforations. This arrangement may be modified by the employment of a timing switch in which case the shutter may be dispensed with.