Patent GB-427692-A (GB)
Title: Improvements in and relating to sheet feeding mechanisms
IPC: B41F21/05
Filed: 1934-07-11
Abstract: 427,692. Feeding sheets. POLLAK, J. E., 20, Holborn, London.-(Faber & Schleicher Akt.-Ges. ; 8, Sedanstrasse, Offenbach-on-Main, Germany) July 11, 1934, No. 20375. [Class 100 (i)] Sheet - carriers and registering - devices.-A sheet-feeding device comprises a set of grippers and means impressing on the grippers a continuous cyclic movement of varying speed such that the speed of the grippers, which is equal to the peripheral speed of the impression or other equivalent cylinder in a printing or other machine at that point where the sheet is transferred from the grippers to the cylinder, is accelerated up to the peripheral speed of the cylinder from a lower speed at which the grippers initially engage the sheet. The grippers may move in a circular path, or they may be moved in a rectangular path by a chain or the like ; in the latter case one of the sprocket wheels is driven at varying speed. As shown, the rotary impression cylinder 111 of a printing- press is provided at each side with spur gearwheels secured to the shaft 127 of the cylinder, each driving, through similar sets of gear-wheels 116<a>, 118<a>, 119<a> and 120<a>, two gear-wheels 121<a> loosely mounted adjacent each end of a shaft 122, on which are secured arms carrying grippers 114. Fixed to each spur-wheel 121<a> is a bevel gear, and fixed to the shaft at each end and spaced apart from the bevel gear is another bevel gear 126<a>. Two other bevel gears 125<a>, each meshing with each pair of the above bevel gears, are supported by rocking frames 124<a> which turn loosely around the shaft 122, so that the bevel gears 125<a> act as planetary wheels. Two cams 128, 129 secured to one end of the shaft 127 of the cylinder 111 actuate, through rollers, levers 133, 134, respectively, mounted loosely at 132. The lever 133 is connected by a rod 135 with one of the frames 124<a>. A spring 139 is mounted between an extension 138 on the lever 134 and the lever 133, and an adjusting-screw 137 in an extension on the lever 133 bears on the lever 134. At the opposite end of the shaft 127 an eccentrically-mounted pin carries a spring 141 (not shown) which is connected to the other frame 124<a>. The end faces of the cylinder 111 are provided with teeth 143 which mesh with teeth 144 fixed to the grippers 114 at the moment at which the grippers transfer a sheet to the grippers on the cylinder. Sheets are placed or fed on to a table 145 and registered. An oscillating feeding device 146, which may have a variable rocking or rotating motion, has grippers thereon for transferring the sheets from the table to the intermediate grippers 114, and is also provided with teeth 147 which engage the teeth 144 on the grippers 114 during the transfer of the sheets. When the frames 124<a> are stationary, the shaft 122 and grippers 114 are rotated at a constant speed, but the cam 128 acting through the levers 133, 135 superimposes on the frames by the aid of the planetary bevel gears 125<a>, an oscillatory movement with the result that the grippers 114 rotate at varying speed. The cam 128 is shaped to allow the grippers 114 to take off the sheets from the grippers on the device 146 at the speed of the latter, and to deliver the sheets to the cylinder 111 at the speed of that cylinder. The springs 139, 141 take up the play or back-lash in the levers and gear-wheels, the eccentrically mounted pin moving in sympathy with the movements of the frames 124<a> so that the spring 141 is only tensioned to a slight extent, and the cam 129 being so shaped that the extension 138 on the lever 134 does not compress the spring 139 to any great extent; these springs also facilitate engagement of the teeth 144, 147, and 144, 143 during transfer of the sheets. In a modification, the spring 141 is dispensed with, and a spring is arranged between two gear-wheels in the driving arrangement of the frames 124<a>. Also, the cam 129, lever 134, and spring 139 may act independently on the frame 124<a> instead of through the levers 133, 135. The grippers 114, and those on the device 146, may be mechanical or pneumatic, and the sheets may be registered by known means when in motion. Further, the sheets on the table 145 may be moving instead of stationary, and the device 146 may be rocked or rotated at either constant or varying speed, or the device 146 may be eliminated and the sheets fed to the grippers 114 direct from the table.