Improvements in or relating to envelope making machines

摘要

An applicator for applying a pressure-sensitive adhesive, e.g latex, to envelopes made in a rotary machine, comprises a rotor having a series of arcuate, adhesive-applying members which are successively movable through an applying station, and a pair of co-operating envelope-conveyer belts so arranged that envelopes fed thereto with the surfaces to be coated facing upwards, are carried in inverted position at the adhesive-applying station, and are delivered from the applicator with the adhesive-bearing surfaces facing upwards. The invention is described as applied to a rotary envelope-making machine as described in U.S.A. Specification 1,774,536 and in which the envelopes are advanced continuously by rollers 2 driven by a common longitudinal countershaft, coated with gum on the sealing flaps, and delivered to a drying wheel 8, which may be as described in U.S.A. Specification 1,834,567. A conventional gumming mechanism comprising a gum pan 9, pick-up roller 10, transfer-roller 11 and applicator roller 12 is provided for use as an alternative to the device of the invention. This comprises a belt 40 which is trained around pulleys or rollers 29, 34, 48, 49, 30 and 51, and a belt 41 which passes around pulleys or rollers 31, 37, 38, 36, 32, 39 and 45. The belts have parallel runs 42, 46; 47, 43 and 50, 44, which co-operate to carry envelopes presented by the rollers 2 over the rollers 34, thence in inverted position to the roller 36, and finally deliver them to the conveyer belt 25 for presentation to the drying drum 8. While the envelopes are inverted, strips of latex are applied by applicators such as 59, which are adjustably mounted on the shaft 58. Each applicator comprises a hub 61 from which extend legs 63 carrying arcuate shoes 64, which move through latex in the receptacle 57 and carry a film of latex past a scraper and gauging mechanism 66 which includes an adjustable scraper blade and side scrapers such as 78. The remaining film of latex is then applied to the envelopes which are gripped between the belt runs 43, 47 by pressure devices 93, 94 comprising spring-urged rollers 97, 98 acting on the belts. The portions of the envelope to which latex is applied are supported by a pivoted spring-urged platen 105 having its position adjustable by a set-screw 107. When the machine is in operation the applicator shaft 58 is driven in timed relation with the rollers 2 by a chain-and-sprocket drive connected to their common driveshaft; when the machine is stopped, it may continue to be driven, but at a lower speed, by a separate motor and chain drive, the sprockets on the shaft 58 incorporating an over-running mechanism.