Patent GB-416104-A (GB)
Title: Improvements in and relating to feeding devices for webs in printing and like machines
IPC: B41F13/02
Filed: 1933-03-24
Abstract: 416,104. Systems for transmitting mechanical power. GROZIER, T. H., 14, Mitchell Street, Greenwich Point, Sydney, Australia. March 24, 1933, No. 8988. [A Specification was laid open to inspection under Sect. 91 of the Acts, Sept. 25, 1933.] [Class 38 (iv).] In an automatic register-governing and correction apparatus for controlling the unwinding and synchronous feeding of a rolled web of material provided with register-defining indications, and arranged to form an inset web or to be further treated in a web-treating machine, there is provided automatic web-tension governing means interdependent with automatic register-correction means to maintain the register of the web during insetting &c., within a specified range of tolerance determined by early and late limits of arrival of the register-defining indications at any given point, the arrangement being such that by aid of a brake acting on the spindle of the web roll, the web-tension governing means controls the unwinding of the rolled web and prevents oscillation fluctuations in the feeding thereof as the web is advanced or retarded by the register-correction means, which controls web-feeding mechanism positively connected and normally synchronized with the web-treating elements of the machine. The pre-printed inset web W, Fig. 1, after being rewound on the spindle 2 in position 1<a> by rotating it by contact with driven rollers 97, 98, is led from reel position 1 over a compensating roller 25, guide rollers 26, 27, and a floating tension-regulating roller 18 to feed rollers 28, 29, which are geared together. The roller 29 is fixed to its shaft 35, while the roller 28 is loose on a shaft 34, which is constantly driven at a speed synchronous with the speed of the main press &c., by a suitable fixed or infinitely variable speed gear. The roller 28 carries a casing 55, Figs. 4 and 5, in which are mounted shafts 63, 64 carrying gears 62 meshing with gears 61 on a worm 57, mounted in supports 59 fixed to the casing. The worm 57 engages a worm-wheel 56 fixed to the shaft 34, so that the shaft 34 drives the roller 28 through the wormwheel 56 and the worm 57, but the speed of the roller may be advanced or retarded by rotating one or other of the shafts 62. In the arrangement shown in Figs. 4 and 5, this rotation is brought about by two metal discs 87 mounted on the shafts 63 so that a portion of each disc moves in a gap between the side-walls 81, 82 of fixed annular electromagnets 79, 80. According to which of these electromagnets is energized, a braking action is applied to one side of a disc 87, thereby causing this disc and its shaft 62 to turn as the casing 55 rotates on the shaft 34. The electromagnets may comprise a number of separate segments spaced around the periphery of the casing 55. In an alternative form, Fig. 9, electromagnets 89 are fixed to the machine frame and serve to operate plungers 90 which are thereby appropriately projected into the path of sprocket wheels 91 carried by the shafts 63, 64, and cause one of the shafts to rotate to vary the speed of the roller 28 ; the pins 90 are returned by cam-surfaces 92 carried by the casing 55. Each electromagnet 79, 80, or each pair of electromagnets 89, is connected to a contact member forming a distributer over which wipes a contact maker driven in synchronism with the main press, and which serves as a timing - device 68. Cam - operated spring contacts or other distributers may be used. The variable speed of the roller 28 is controlled by a photo-electric cell or the like 65 which receives light from a beam 66, suitably modulated by opaque or transparent spots M provided at suitable intervals along the length of the web. The impulses set up in the cell 65 by the spots M after amplification operate relays in the circuits of the timing-device 68 ; if the web is in register with the main press the rotating contact engages neither of the fixed contacts at the instant these impulses are transmitted, but should the web be out of register one or other of these contacts is so engaged, and operates a relay to close the circuit of one of the electromagnets 79, 80, or one of the pairs of electromagnets 89, and an intermittent variation in the speed of the roller 20 is thereby set up appropriate to the lack of register of the web. To prevent this speed change from being reflected in the web tension, and also to compensate for the change in tension due to the decreasing diameter of the roll 1, the floating roller 18 is arranged to control brake shoes 6 and 7, which engage a brake drum 5<a> on the roller spindle. The shoes 6, 7 are pivoted at 11 and are attached to a spring-held shaft 12, which is engaged by a cam roller 13 carried by a shaft 14, to which is attached by arms 17 the floating roller 18. As the position of the roller changes in accordance with the web tension, the braking effect is varied by the cam 13 which tightens or loosens the brake shoes 6, 7, sudden changes being prevented by an adjustable counterweight 21 and a dashpot 24, the plunger of which is mounted on an arm 20 attached to the shaft 14. According to the Specification as open to inspection under Sect. 91, the inset web feed may be manually controlled, when the photoelectric cell and its amplifying circuit are dispensed with, the electromagnets 79, 80, Figs. 4 and 5, and timing-device 68 being associated in circuits controlled by hand switches, while in the modification of Fig. 9, the electromagnets 89 may also be controlled by hand switches ; alternatively the electromagnets 89 may be omitted the plungers 90 being pushed into the path of the star wheels by hand. This subjectmatter does not appear in the Specification as accepted.