Patent EA-002505-B1 (EA)
Title: Method for hot pressing workpieces and hot pressing machine therefor
Inventor: SCHONENBERGER RAYMOND
IPC: B21J5/08
Filed: 1999-04-19
Abstract: 1. A method for the hot-pressing of workpieces, in which a workpiece (4) heated to forging temperature is descaled outside a die (5;105) by pre-upsetting with a press ram (1) and is thereafter compression moulded to the desired shape within one or a plurality of dies (5;105), wherein the pre-upsetting and the compression moulding are both accomplished in said die (5;105) by the same press ram (1) during a single cycle of movement of said press ram (1). 2. The method according to claim 1, wherein, during pre-upsetting, the workpiece is held outside said die by an extended ejector (7;107) of said die (5;105) and, after pre-upsetting, is conveyed by pressure generated in response to the forward movement of said press ram (1) into said die (5;105), where it is compression-moulded as a result of the further forward movement of said press ram (1). 3. The method according to claim 2, wherein the workpiece (4) is already being moved towards said die (5;105) during pre-upsetting, but the speed of movement of said workpiece during pre-upsetting is less than the speed of movement of said workpiece after pre-upsetting. 4. A hot-forming machine for hot-pressing workpieces according to claims 2 or 3, said machine comprises at least one die 95;105), an ejector (7;107) that is moveable between an extended position and a retracted position, and a forwardly and backwardly movable press ram (1), wherein comprising delay means by which the movement of said ejector (7;107) from its said extended position to its said retracted position in response to the forward movement of said press ram (1), via a workpiece (4) arranged between said ejector (7;107) and said press ram (1), is delayed such that the workpiece (4) is pre-upset outside said die (5;105) 5. The hot-forming machine according to claim 4, wherein said delay means comprises a control piston (8) positioned in a pressure chamber (28) and connected directly to said ejector (7;107), fluid supply means for supplying fluid to said pressure chamber (28), and fluid discharge means for discharging fluid from said pressure chamber (28), said fluid discharge means being adapted such that the discharge of fluid from said pressure chamber occurs partially with a delay, thereby delaying the retraction of said control piston (8) and said ejector (7). 6. The hot-forming machine according to claim 5, wherein said fluid discharge means comprises a fluid discharge line (23) and a throttle (25) positioned within said fluid discharge line. 7. The hot-forming machine according to claim 5, wherein said fluid discharge means comprises a fluid discharge line (23) and a pressure relief valve (26) that opens only at a predetermined fluid pressure and which is positioned within said fluid discharge line. 8. The hot-forming machine according to claim 5, wherein said fluid discharge means comprises a fluid discharge line which is opened and closed by means of a control pin (30). 9. The hot-forming machine according to claim 8, wherein said control pin (30) is connected to a forwardly and backwardly movable ejector rod (17) for moving said ejector (32) into its said extended position, and further comprising means (32) for moving said ejector rod (17) backwards prior to the movement of said ejector (7) to its said retracted position. 10. The hot-forming machine according to claim 4, further comprising a rotatable cam (160) for controlling the movement of said ejector (107) between its said extended position and its said retracted positions, said cam being shaped and its rotation coordinated with the forward and backward movement of said press ram such that the movement of said ejector (107) from its said extended position to its said retracted position occurs with a delay. 11. The hot-forming machine according to claim 10, wherein the position of said rotatable cam (160) relative to the position of said press ram is adjustable. 12. The hot-forming machine according to claim 11, further comprising an ejector lever (150) that is moveable outwards and inwards by means of said rotatable cam (160) and which moves said ejector (107) between its said extended position and its said retracted position via an ejector rod (117).