Patent GB-674888-A (GB)
Title: Improvements in or relating to sheet separating and forwarding machines
IPC: B65H3/08
Filed: 1948-04-22
Abstract: 674,888. Feeding sheets. BACKHOUSE, H. T. April 22, 1949 [April 22, 1948; Feb. 9, 1949], Nos. 10709/49. Divided out of 674,842 and 3586/49. Class 100 (i). In a sheet separating and forwarding apparatus wherein a suction gripper engages the top sheet of a pile at or near its rear edge to raise the sheet and forward it to a printing or other machine, the gripper. 208 is raised and lowered by a piston-and-cylinder 200, 201 (or equivalent bellows or diaphragm device) to which suction is applied, and which is oscillated to effect the movements of the gripper over the top of the pile, the arrangement being such that free communication exists between the mouth of the gripper and the cylinder when the gripper is lowered to engage a sheet, and the closing of the mouth by the sheet enables the suction to raise the piston and gripper with the sheet; at the end of the forward movement of the cylinder, air is admitted to the gripper only, to release the sheet, the cylinder and gripper being retained in the raised position by the maintenance of the suction in the cylinder. Suction is applied continuously to the cylinder 201 from a tubular shaft 4 about which the cylinder oscillates, and tends to move upwardly the piston 200 against the action of a spring 204. The interior of a tubular piston rod 206 is open to the cylinder at its upper end. At its lower end, the rod 206 is enlarged and carries one or more suction grippers 208. In the enlarged part is formed a slide-way 211 for a valve comprising two parts 212, 213 urged apart into sealing engagement with the walls of the slideway by an intermediate rubber strip 214. A passage 217 is provided in the valve so that when the cylinder moves to its rearward position and the valve is moved to the position shown, by engagement with a stop 221, the passage 217 is aligned with the piston rod. Air is now admitted to the cylinder via gripper 208, passage 217 and rod 206 so that the suction is destroyed and the gripper moves downwardly on to the sheet. The closure of the gripper mouth by the sheet reestablishes the suction and the gripper and sheet are raised. At the forward end of the cylinder travel, another stop 220 moves the valve to the opposite end of its travel where passage 217 is out of alignment with the piston rod and the gripper is cut off from the cylinder but is put into communication with atmosphere by passages 218, 219 so that the sheet is released. The gripper remains raised because the suction is maintained in the cylinder until the stop 221 again reverses the valve. The gripper is attached to a hollow shaft 230 mounted in the end of the piston rod 206, and the shaft has a spring- controlled arm 231 attached thereto with a roller 232 at its end engaging a track 233 to maintain the gripper axis in proper relation to the top of the pile as the cylinder oscillates. The apparatus preferably includes a presser foot formed with a nozzle for directing an air blast beneath the separated sheet and a second nozzle for directing an air blast on to the rear of the pile to " fluff " the sheets as described in Specifications 674,842 and 674,844.