GB478362A - Improvements in or relating to sheet feeding mechanism for printing machines - Google Patents

Abstract

478,362. Printing - machines. HOE & CO., Ltd., R. (Hoe & Co., Inc., R.) July 17, 1936, No. 19896. [Classes 100 (i) and 100 (ii)] Rotary machines ; feeding sheets.-A rotary printing- machine of the kind in which the sheets are carried through rotary couples, or a single couple, by grippers on chains is constructed so that the gripper mechanisms have imparted to them in passing each unit such a movement relative to the conveyer chains as will cause the grippers to reduce the tension exerted on a sheet after the sheet is gripped by the printing-couples that the sheet will be propelled during the printing operations by the couples. The sheets may be severed from a web fed from a feed roll to rollers fitted with transverse cutters, or sheets may be fed direct from a pile L, Fig. 1, by sheet-feeding mechanism including sheet forwarding rolls 10<1> and a pair of cylinders 136, 137 to grippers on chains 138, Fig. 1, which feed the sheets through printing-couples B<1>, C<1>, D<1>, and finally to a delivery mechanism E, all driven in synchronism by worm gearing from a horizontal shaft 133. To ensure accurate registration, the rollers 10<1> are arranged to advance the sheet faster than the motion of registration stops 137<1> on the cylinder 137, so that the sheets are buckled and are maintained in contact with the stops by the tension of the sheet due to the buckling. The grippers of cylinder 137 transfer the sheets to grippers 158 on carriers 139, Fig. 2, which are adapted to register in cut-out portions of the impression cylinders. The carriers 139 are secured in adjustable manner to the chains 138. The spring-controlled grippers 158, which engage pads 162 in the carriers 139, are opened by cams situated at the feed-in cylinder 137 and at the delivery cylinder. The gripper support comprises a pair of pivoted bifurcated members 139 connected to the chain by a pivot 143 at one end, and at the other end by a pin-and-slot connection 140 which allows the grippers 158 to move slightly radially when the members 139 pass over the pulleys of the impression cylinders. This causes the sheets to be fed through the printing-couple by the friction of the printing-members. The downward movement of each member 139 is caused by the action of a cam 151 on a roller 148 mounted in the bifurcation of the member, and this movement is limited by a segmental plate 153 which serves as an abutment for the member 139, the movement being controlled by the engagement of a groove of a sheaf 144 with a segmental plate 154 on the sprocket wheel 145. The gripper mechanism is carried by a T- shaped bracket 156, Fig. 5, to which is bolted the support of the gripper seat 162. The grippers 158 are pressed by springs 164 against the seat 162 when a pivoted roller 168 engages in a recess in a shaft 173. This shaft is actuated by a cam 179, Fig. 2, secured to the machine frame which engages a roller 178 on a bracket 174 connected by a screw to the shaft 173. The gripper chains may be controlled between the printing-couples by means of upper and lower parabolic guides 181, 182; 188, 189, Fig. 6, which are spring-supported and which cause the chains to have a steady movement free of whipping.