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.

To provide a die cushion device which is inexpensive, functional, and capable of locking completely (at or below the slide bottom dead center). The die cushion device includes a cushion pad, a hydraulic cylinder that moves the cushion pad up and down, and a hydraulic closed circuit connected to a die cushion pressure generation chamber of the hydraulic cylinder. The hydraulic closed circuit includes a cushion pad lowering pressure generation line and a second system pressure line in addition to a die cushion pressure generation line and a first system pressure line. When the cushion pad is locked at the bottom dead center, the cushion pad lowering pressure generation chamber is connected to the first system pressure line, and the die cushion pressure generation chamber is connected to the second system pressure line such that the cushion pad is held at or below the slide bottom dead center.

To provide a die cushion device which is inexpensive, functional, and capable of locking completely (at or below the slide bottom dead center). The die cushion device includes a cushion pad, a hydraulic cylinder that moves the cushion pad up and down, and a hydraulic closed circuit connected to a die cushion pressure generation chamber of the hydraulic cylinder. The hydraulic closed circuit includes a cushion pad lowering pressure generation line and a second system pressure line in addition to a die cushion pressure generation line and a first system pressure line. When the cushion pad is locked at the bottom dead center, the cushion pad lowering pressure generation chamber is connected to the first system pressure line, and the die cushion pressure generation chamber is connected to the second system pressure line such that the cushion pad is held at or below the slide bottom dead center.

A die cushion device includes a hydraulic cylinder that supports a cushion pad and generates die cushion force when the slide of the press machine descends, a first hydraulic circuit that is connected to a cap side hydraulic chamber of the hydraulic cylinder, and a second hydraulic circuit that is connected to a rod side hydraulic chamber. Before die cushion force control starts, the second hydraulic circuit of the die cushion device causes hydraulic oil in the rod side hydraulic chamber to be prevented from flowing out, and the first hydraulic circuit of the die cushion device causes the cap side hydraulic chamber to be pressurized.

A die cushion device includes a hydraulic cylinder that supports a cushion pad and generates die cushion force when the slide of the press machine descends, a first hydraulic circuit that is connected to a cap side hydraulic chamber of the hydraulic cylinder, and a second hydraulic circuit that is connected to a rod side hydraulic chamber. Before die cushion force control starts, the second hydraulic circuit of the die cushion device causes hydraulic oil in the rod side hydraulic chamber to be prevented from flowing out, and the first hydraulic circuit of the die cushion device causes the cap side hydraulic chamber to be pressurized.

A spring assembly is provided which decreases the fatigue and wear on the springs of the assembly. The spring assembly includes upper and lower pistons separated by a substantially incompressible fluid. The lower piston is attached to one or more springs. The surface area of the upper surface of the lower piston is greater than the surface area of the lower surface of the upper piston. As such, the springs are deflected by a distance less than the distance traveled by the upper piston. By decreasing the length the springs are compressed, the springs are subject to less fatigue and wear. As a result, the life span of the springs is increased and the maintenance required of the spring assembly is minimized relative to that of typical spring assemblies.

A spring assembly is provided which decreases the fatigue and wear on the springs of the assembly. The spring assembly includes upper and lower pistons separated by a substantially incompressible fluid. The lower piston is attached to one or more springs. The surface area of the upper surface of the lower piston is greater than the surface area of the lower surface of the upper piston. As such, the springs are deflected by a distance less than the distance traveled by the upper piston. By decreasing the length the springs are compressed, the springs are subject to less fatigue and wear. As a result, the life span of the springs is increased and the maintenance required of the spring assembly is minimized relative to that of typical spring assemblies.

The disclosure pertains to a fine blanking press comprising a first press unit comprising a first press drive for driving the first press unit in a first driving movement during a fine blanking process step, and a second press unit wherein the second press unit is driven in a second driving movement at least partially during the first driving movement of the first press unit, and wherein a force control unit exerts a counter force against a force exerted by the first press unit during its first driving movement, and wherein the force control unit comprises at least one sensor and a controller operative to receive measuring data collected by the at least one sensor, and wherein the controller is configured to carry out a closed loop control on basis of the received measuring data. The disclosure further pertains to a method for operating a fine blanking press.

A plurality of hydraulic cylinders capable of adjusting height direction positions of a plurality of die-cushion pins that are inserted into a plurality of die-cushion pin holes formed in a bolster, respectively, are arranged in a lattice state on a cushion pad, and the hydraulic cylinder faced with a die-cushion pin located below a projection surface of a blank holder in the plurality of hydraulic cylinders is selected. Then, by independently adjusting a height direction position of a piston rod of each of the selected hydraulic cylinders, respectively, the shim adjustment of substantially each of the die-cushion pins is realized.

A plurality of hydraulic cylinders capable of adjusting height direction positions of a plurality of die-cushion pins that are inserted into a plurality of die-cushion pin holes formed in a bolster, respectively, are arranged in a lattice state on a cushion pad, and the hydraulic cylinder faced with a die-cushion pin located below a projection surface of a blank holder in the plurality of hydraulic cylinders is selected. Then, by independently adjusting a height direction position of a piston rod of each of the selected hydraulic cylinders, respectively, the shim adjustment of substantially each of the die-cushion pins is realized.