A controllable force cushion device that can be programmed to provide a variable and/or pulsating force that can be used in any application where force control is desirable. The frequency of the pulsation can be adjusted to suit different applications and/or circumstances (e.g., forming of sheet metals in die applications, etc.). The cushion can comprise one or more manifolds containing hydraulic cylinders that can be compressed during operation pushing fluid through a proportional relief valve that can be controlled by a motion control device, thereby creating a desired force. Material (e.g., sheet metal, etc.) flow can be controlled by using a gap control method. In use, the variable pulsating, gap control, auto-learning press cushion device of the present invention can optionally be mounted to the underside of a press bolster and can be used in conjunction with a stamping press.

An industrial gas spring with a pressure chamber in a casing with an end wall, a piston rod received at least in part in the casing for reciprocation between extended and retracted positions and a pressure relief assembly carried by the end wall. The pressure relief assembly may have a membrane communicating with the pressure chamber and a plunger configured to breach the membrane when engaged and moved by the piston rod when it overtravels its design intended retracted position.

A die cushion device includes four hydraulic cylinders that support a cushion pad, a die cushion load controller that controls each of the hydraulic cylinders and generates a die cushion load on the cushion pad, and a die cushion position controller that controls each of the hydraulic cylinders to control a position of the cushion pad. In a case where only a left part is produced with a left die by a press machine, the die cushion load controller performs die cushion load control on two hydraulic cylinders on the left side, and the die cushion position controller performs die cushion position control on two hydraulic cylinders on the right side.

A die cushion device includes four hydraulic cylinders that support a cushion pad, a die cushion load controller that controls each of the hydraulic cylinders and generates a die cushion load on the cushion pad, and a die cushion position controller that controls each of the hydraulic cylinders to control a position of the cushion pad. In a case where only a left part is produced with a left die by a press machine, the die cushion load controller performs die cushion load control on two hydraulic cylinders on the left side, and the die cushion position controller performs die cushion position control on two hydraulic cylinders on the right side.

An industrial gas spring with a pressure chamber in a casing with an end wall, a piston rod received at least in part in the casing for reciprocation between extended and retracted positions and a pressure relief assembly carried by the end wall. The pressure relief assembly may have a membrane communicating with the pressure chamber and a plunger configured to breach the membrane when engaged and moved by the piston rod when it overtravels its design intended retracted position.

An industrial gas spring with a pressure chamber in a casing with an end wall, a piston rod received at least in part in the casing for reciprocation between extended and retracted positions and a pressure relief assembly carried by the end wall. The pressure relief assembly may have a membrane communicating with the pressure chamber and a plunger configured to breach the membrane when engaged and moved by the piston rod when it overtravels its design intended retracted position.

An industrial gas spring with a pressure chamber in a casing with an end wall, a piston rod received at least in part in the casing for reciprocation between extended and retracted positions and a pressure relief assembly carried by the end wall. The pressure relief assembly may have a membrane communicating with the pressure chamber and a plunger configured to breach the membrane when engaged and moved by the piston rod when it overtravels its design intended retracted position.

A double-blank detecting apparatus for a press machine that is provided with a die cushion apparatus and is configured to form blanks one by one automatically and repeatedly. The double-blank detecting apparatus includes: a position signal acquiring unit configured to acquire a slide position signal indicating a position of a slide of the press machine; a load signal acquiring unit configured to acquire a die cushion load signal indicating a die cushion load generated on a cushion pad of the die cushion apparatus; and a double-blank detector configured to detect a state in which a plurality of blanks are stacked as a double blank based on the slide position signal acquired by the position signal acquiring unit and the die cushion load signal acquired by the load signal acquiring unit.

A double-blank detecting apparatus for a press machine that is provided with a die cushion apparatus and is configured to form blanks one by one automatically and repeatedly. The double-blank detecting apparatus includes: a position signal acquiring unit configured to acquire a slide position signal indicating a position of a slide of the press machine; a load signal acquiring unit configured to acquire a die cushion load signal indicating a die cushion load generated on a cushion pad of the die cushion apparatus; and a double-blank detector configured to detect a state in which a plurality of blanks are stacked as a double blank based on the slide position signal acquired by the position signal acquiring unit and the die cushion load signal acquired by the load signal acquiring unit.

A piston cylinder device (1) comprising a cylinder (2) with a first and a second end and a guide (6), such that a pressure chamber (8) is formed in the cylinder. A piston (12) is moveable in the pressure chamber (8). The guide (6) is fixedly secured to the cylinder (2) by a lock ring (7). A sealing means (9) is arranged to seal between the guide (6) and an inner wall of a tubular wall (3) of the cylinder (2) to prevent fluid leakage from the pressure chamber (8) to the surroundings. The piston cylinder device (1) is provided with a material weakening zone (13) arranged in the inner wall of the tubular wall (3) of the cylinder (2) axially between the lock ring (7) and the second end (20) of the cylinder (2), the material weakening zone (13) being arranged to be deformed or sheared against the lock ring (7) at a predetermined level of impact of the piston (12) against the guide (6). A leakage gap (14) is arranged to interrupt the sealing means (9) upon deformation or shearing of the material weakening zone (13) such that gas from the pressure chamber (8) is allowed to leave the pressure chamber (8) through said leakage gap (14) to the surroundings.