Abstract: A hydraulic drawing cushion (17) for a drawing press (10) includes at least one hydraulic cylinder (21) comprising a piston rod (27) that causes a total force (G) to act on the metal sheet holding ring (20). The hydraulic cylinder (21) comprises a hydraulic work circuit (37) to generate a hydraulic work force (A) in a work direction (Z) to act on a ring part (28) to which a force can be applied on both sides. Independently, a spring force (F) acts on the piston (26). The spring force (F) is neither controlled nor adjusted, but is preset. Preferably, the spring force (F) is exclusively a function of the position or location of the piston (26) relative to the cylinder housing (25). The total force (G) acting on the piston (26) results from the addition of the vectors of the work force (A) and the spring force (F).

Abstract: A hydraulic drawing cushion (17) for a drawing press (10) includes at least one hydraulic cylinder (21) comprising a piston rod (27) that causes a total force (G) to act on the metal sheet holding ring (20). The hydraulic cylinder (21) comprises a hydraulic work circuit (37) to generate a hydraulic work force (A) in a work direction (Z) to act on a ring part (28) to which a force can be applied on both sides. Independently, a spring force (F) acts on the piston (26). The spring force (F) is neither controlled nor adjusted, but is preset. Preferably, the spring force (F) is exclusively a function of the position or location of the piston (26) relative to the cylinder housing (25). The total force (G) acting on the piston (26) results from the addition of the vectors of the work force (A) and the spring force (F).

Abstract: The invention resides in a hydraulic cylinder (23) for a hydraulic drawing cushion (20) of a drawing press (10). The hydraulic cylinder (23) includes a first operating chamber (47), a second operating chamber (48), and a third operating chamber (53). An annular piston (45) with a first piston surface area (49) and a second piston surface area (50) separates the first operating chamber (47) from the second operating chamber (48). The first and the second piston surfaces (49, 50) have the same size. A front surface of the piston rod (33) forms a third piston surface (54) which is larger than the first and second piston surfaces. The third piston surface (54) delimits the third operating chamber (53) of the hydraulic cylinder (23). The first and the second operating chambers (47, 48) are provided for controlling the position and/or the movement of the piston rod (33). The third operating chamber (53) serves to control the metal sheet clamping force of the drawing press via the piston rod (33).

Abstract: The invention resides in a hydraulic cylinder (23) for a hydraulic drawing cushion (20) of a drawing press (10). The hydraulic cylinder (23) includes a first operating chamber (47), a second operating chamber (48), and a third operating chamber (53). An annular piston (45) with a first piston surface area (49) and a second piston surface area (50) separates the first operating chamber (47) from the second operating chamber (48). The first and the second piston surfaces (49, 50) have the same size. A front surface of the piston rod (33) forms a third piston surface (54) which is larger than the first and second piston surfaces. The third piston surface (54) delimits the third operating chamber (53) of the hydraulic cylinder (23). The first and the second operating chambers (47, 48) are provided for controlling the position and/or the movement of the piston rod (33). The third operating chamber (53) serves to control the metal sheet clamping force of the drawing press via the piston rod (33).

Abstract: In an electrohydraulic drawing press drive, particularly an electrohydraulic drawing cushion drive including a hydraulic circuit with at least one motor which is operable as a drive motor or as a pump and at least one hydraulic pump which is operable as a pump or as a drive motor, an electric drive motor which is also operable as generator is connected to the hydraulic motor in order to drive the hydraulic motor or to be driven thereby and a control unit is provided for controlling at least one of the electric motor and the hydraulic pump.

Abstract: A vacuum system, particularly for vacuum grippers, has a fluid entrainment pump for generating the vacuum which, when the required vacuum is built up, is supplied with a throttled compressed-air flow. For the throttling of the compressed-air flow, a controlled throttle device is used which, as a function of the detected vacuum value, throttles the compressed-air flow to the fluid entrainment pump when the desired vacuum value has been reached or exceeded.