GB725966A - Improvements in or relating to drawing buffers for presses - Google Patents

Abstract

725,966. Cupping. SCHULER AKT.-GES., L. March 9, 1953 [April 2, 1952], No. 6459/53. Class 83 (4). An hydraulically cushioned drawing buffer for a cupping press is characterized in that the buffer cylinder which is guided on a stationary piston is operated pneumatically or hydraulically and encloses all other elements of the drawing buffer. The buffer cylinder 1 is guided externally in a cylinder 3 formed on the machine frame 2 and internally by a stationary piston 4. Pins 6 connected with the drawing tool (not shown) rest on the end 5 of the buffer cylinder. The piston 4 has an annular shoulder 7 and the lower end of the buffer cylinder is restricted by a threaded ring 8, a packing sleeve 10 and a retaining ring 9 so that a fluid-tight chamber 11 is formed between the buffer cylinder and the piston 4. A channel 12 connects the chamber 11 with a non-return inlet valve 13 which controls the flow of pressure fluid 14 from a chamber 15 formed within the buffer cylinder. The chamber 15 also contains compressed gas supplied through a pipe 16. A return flow release valve 17 also communicates with the chamber 11, said valve being operated by an hydraulically or pneumatically actuated piston 18. The valve 17 controls the fluid return flow through a channel 23 into which is built a throttle 25 adjustable by a tapered shank 24 and an outflow non-return valve 26. In operation when the buffer cylinder is depressed by the pins 6 the chamber 11 enlarges and pressure fluid is drawn from the chamber 15 through the inlet valve 13. When the press ram moves upwards after the drawing operation the return of the buffer cylinder is delayed by the valve 17 to prevent damage to the drawn article. After the ram has moved a predetermined distance the valve 17 is opened by supplying fluid pressure to the chamber 21 and releasing the pressure from chamber 19 of the valve thus the pressure fluid in the chamber 11 meters back to the chamber 15 and the buffer cylinder returns to its initial position. The delaying effect of the valve 17 can be overcome by removing pressure fluid from both sides of the piston 18 in which case a spring 27 or the weight of the piston holds the valve 17 open so that the buffer cylinder moves upwards immediately after reaching its lowest position.