GB483443A - Improvements in offset printing machines and to transfer rollers therefor - Google Patents

Abstract

483,443. Printing-machines. OXVAR, Ltd. (Oxford Varnish Corporation) July 27, 1937, No. 20808. [Class 100 (iij] A hollow transfer roll for an offset printing- machine has a flexible transfer surface which can adapt itself to correspond with irregular contours on workpieces, internal means being provided to lock the flexible surface against deformation when desired. The transfer roll can be used manually by providing a pair of handles on its shaft, or can as described be incorporated in an offset decorating-machine. A pattern roll 10, preferably intaglio, receives colour from a duct roll 15 and transfers it to a transfer roll 20. The roll 20 is supported on a shaft 21 by a pair of end plates 80 which are secured to the opposite ends of the roll and are rotatably mounted in the arms of a yoke 19. The roll 20 has a core comprising a number of relatively thin rings 24 and a central thicker ring 25 each of which, apart from the two end ones, is provided with two central openings, a smaller one 28, and a larger one 27. Discs 26, all of the same diameter and corresponding to the openings 28 in the rings, are secured to the shaft 21 in 'spaced relationship, and adapted to be moved by the shaft to register with either the smaller or larger openings in the rings, whereby in the former positions they hold the rings rigid to form a cylindrical transfer roll, and in the latter positions they allow the rings to move transversely to the shaft 21 and relatively to each other as shown in Fig. 4. If desired, the openings in the rings may be of the same diameter, and the rings may have two different diameters. A hollow cylindrical body 30 of a glue and glycerine compound embraces the rings 24, 25, and intermediate the body and the rings is a tubular sleeve 32 of pre-stretched rubber. The workpiece W is fed between the transfer roll 20 and a platen roll 40 by a pair of endless chains 35 provided with lugs 36 which engage a workholder 43. The roll 20 is oscillated to engage the pattern roll 10 and then to engage the workpiece. To effect this the yoke 19 carrying the shaft 21 of the roll 20 is pivoted on a shaft 46, and a roller on the yoke engages a groove 51 in a rotating cam disc. As the roll 20 moves upward toward the roll 10, the shaft 21 is moved longitudinally by a fixed cam on the machine frame so that discs 26 hold the rings 24, 25 concentric with the shaft. As the roll 20 descends, a further fixed cam moves the shaft 21 in the opposite direction to release the rings whereby the surface of the roll can accommodate itself to the workpiece W. The shaft 41 of the platen roll 40 is power-driven, and is geared to the pattern and transfer rolls, and also to the conveyer chains 35, whereby all are driven in timed relationship with each other.