GB598118A - Improvements in or relating to rotary printing machines - Google Patents

Abstract

598,118. Feeding webs. JONES, K. W. July 20, 1945, No. 18629. [Class 100 (i)] In a web-fed rotary printing machine comprising one or more printing-units each comprising a stereo cylinder 1 and an impression roller 2, and means for maintaining tension on a web 3 as it passes through the units, a suction roller 7 either following or preceding the couple is provided constituting a master control cylinder effective to coordinate the draw of the web with the requirement of the cylinder 1 and maintain accurate register, the roller 7 being driven from the cylinder 1 or roller 2 by gearing co-related with the respective diameters to maintain constant the predetermined relation of the peripheral speeds of the roller 7 and the cylinder 1. The use of a suction roller is said to preclude slip between the web and the roller, any variation in the feed of the web due to variations in the diameter of the stereos being adjusted when gaps between the plates release the web. The roller 7 may be a perforated roller, e.g., as described in Specifications 559,388 and 570,795, or a non-perforated roller in a suction box 9 as described in Specification 598,148. By means of an intermediate gear 8, the roller 7 is driven from the roller 2 at a speed which may allow for known stretch of the web in travelling from the couple 1, 2 to the roller 7. Tension on the web is maintained by a brake on a supply roller 4 or by a suction bar or a suction roller 11 having a peripheral speed less than that of the couple 1, 2, the suction being such that the web can slip. Where the roller 7 precedes the couple, a roller 11 driven faster than the couple follows the latter, the suction allowing slip. A two-colour machine is described, the couples being connected by a gear between the impression rollers. Each couple of a multi-colour machine may have its own rollers 7 and 11.