GB621170A - Improvements in pneumatic bars for controlling the movement of paper in printing andlike machines - Google Patents

Abstract

621,170. Feeding webs; preventing set-off. JONES, K. W. Oct. 31, 1946, Nos. 32351 and 33098. [Classes 100 (i) and 100 (ii)] A pneumatic bar 1 for controlling the movement of paper passing through a printing or like machine, and which is connected to an exhauster when used for tensioning the paper and to a source of pressure when used to prevent set-off, is constructed with a number of grooves 3 of small cross-section, each having communication as by an aperture 2, Fig. 2, with a tube 4 connected to the source of pressure or vacuum, the arrangement being such that the pneumatic action is not materially affected if a web is used which does not cover all the slots 3. The slots 3 are eccentric as shown in Fig. 2, being readily cut in a lathe. A similar arrangement is applied to the air passages 7, Fig. 3, of a bar 6 which is of flat form with the slots 3 formed in a convex surface 6. In Fig. 5 the slots 3 are formed in separate rings 16 which are adjustably mounted on a tube 15 formed with apertures 17 with which the apertures 2 of the slots 3 can be put into or out of register, retaining means being provided to hold the rings in operative or inoperative position. In a modified form the rings are arranged only at the extremities of a fixed central member, the slots 3 of which are in constant communication with the tube 15. In a further modification the tube 15 is formed with a stepped aperture and the outer slots 3 are cut off successively by adjustment of the outer bar 1 relatively to the tube 15. Instead of providing radial apertures 2 the apertures may be formed by cutting the grooves 3 deep enough to penetrate into the interior of the bar 1. Helical grooves may replace the circumferential ones, and each ring or segment may have two grooves of opposite hand crossing one another with the aperture 3 located at the point of intersection.