An apparatus for the controlled return of the stems in cylinders of the types that can be applied to a press for stamping sheet metal, comprising: at least one fluid-operated cylinder), at least one hydraulic accumulator which is fluidically connected to the at least one cylinder by means of a hydraulic circuit which comprises: a duct for the discharge of the working fluid from the at least one cylinder and a duct/branch for the intake of the working fluid in the hydraulic accumulator, a duct for loading the working fluid in the at least one cylinder and at duct/branch for the output of the working fluid from the hydraulic accumulator.

A cushion pin pressure equalizing device that can absorb a variation in height of a plurality of cushion pins and control a die cushion load highly accurately, a die cushion device, and a cushion pin pressure equalizing method are provided. An initial pressure in ascending-side pressurizing chambers of a pressure equalizing hydraulic cylinder group for absorbing a variation in height of cushion pins is controlled so as to be an appropriate pressure. The variation in height of the plurality of cushion pins can be absorbed within a shortest stroke of a slide after the slide comes into collision with a cushion pad so as to equalize die cushion loads that are applied individually to the cushion pins and a target die cushion load can be generated within the shortest stroke of the slide, whereby a response to application of the die cushion load can be stabilized without excessive delay.

A cushion pin pressure equalizing device that can absorb a variation in height of a plurality of cushion pins and control a die cushion load highly accurately, a die cushion device, and a cushion pin pressure equalizing method are provided. An initial pressure in ascending-side pressurizing chambers of a pressure equalizing hydraulic cylinder group for absorbing a variation in height of cushion pins is controlled so as to be an appropriate pressure. The variation in height of the plurality of cushion pins can be absorbed within a shortest stroke of a slide after the slide comes into collision with a cushion pad so as to equalize die cushion loads that are applied individually to the cushion pins and a target die cushion load can be generated within the shortest stroke of the slide, whereby a response to application of the die cushion load can be stabilized without excessive delay.

A method for producing a molded body of particularly steel, and including a hub and a bell-shaped lower part axially connected thereto, in which an inner contour is made in the lower part by non-cutting forming in a convex region. The inner contour includes of ball tracks and cage paths that are concave in the axial direction and arranged in a peripherally alternating manner, for receiving rolling bodies, the cage paths being shallower than the ball tracks. The hub is formed from a rotating round blank and reducing the thickness thereof using at least one pressure roller. The flat region of the round blank that radially connects to the hub is pressed onto contour segments of a rotating first inner contour tool, partially forming the inner contour using at least one axially and radially moving pressure roller to form a preform of the lower part. The fixed preform is pressed against contour segments of a second inner contour tool by a die of partial dies, fully forming the cage paths and ball tracks.

A cushion pin device for a press having a cushion pad in which a blank holder is seated on the top thereof outside a lower mold, and locks a blank holder to an upper mold while pressurizing an edge of a molded panel, includes: a cushion support disposed below the cushion pad, a cushion cylinder connected with a lower part of the cushion pad to move up or down the cushion pad from the cushion support, a linear scale mounted between the cushion pad and the cushion support to measure the position of the cushion pad, a main pressure control unit that keeps internal pressure of each cushion cylinder similarly, and a sub pressure control unit that is interconnected with the main pressure control unit so as to control the locking position of the cushion pad when each cushion cylinder operates.

A cushion pin device for a press having a cushion pad in which a blank holder is seated on the top thereof outside a lower mold, and locks a blank holder to an upper mold while pressurizing an edge of a molded panel, includes: a cushion support disposed below the cushion pad, a cushion cylinder connected with a lower part of the cushion pad to move up or down the cushion pad from the cushion support, a linear scale mounted between the cushion pad and the cushion support to measure the position of the cushion pad, a main pressure control unit that keeps internal pressure of each cushion cylinder similarly, and a sub pressure control unit that is interconnected with the main pressure control unit so as to control the locking position of the cushion pad when each cushion cylinder operates.

A method for regulating output pressure of a hydraulic drive system by using a rotational speed as the actuating variable. The method includes determining a setpoint rotational speed main component of motor drive as a pilot control signal, determining an error rotational speed as a regulating deviation from a comparison of an actual pressure value of the hydraulic drive system and a setpoint pressure value of the hydraulic drive system and adjoining regulating amplifier, adding the determined setpoint rotational speed main component to the determined error rotational speed to create the setpoint rotational speed as the actuating variable, and converting the created setpoint rotational speed into an input rotational speed of the motor drive to drive the hydraulic drive system at the converted rotational speed in order to generate regulated output pressure of the hydraulic drive system which represents actual pressure value.

A method for regulating output pressure of a hydraulic drive system by using a rotational speed as the actuating variable. The method includes determining a setpoint rotational speed main component of motor drive as a pilot control signal, determining an error rotational speed as a regulating deviation from a comparison of an actual pressure value of the hydraulic drive system and a setpoint pressure value of the hydraulic drive system and adjoining regulating amplifier, adding the determined setpoint rotational speed main component to the determined error rotational speed to create the setpoint rotational speed as the actuating variable, and converting the created setpoint rotational speed into an input rotational speed of the motor drive to drive the hydraulic drive system at the converted rotational speed in order to generate regulated output pressure of the hydraulic drive system which represents actual pressure value.

A die assembly for use with a stamping die. The die assembly having a system for monitoring a gas pressure in the stamping die. The system including first and second piston-cylinder assemblies acting on a flag block wherein movement of the flag block corresponds to a pressure change. A sensor detects a movement of the flag block.

A die assembly for use with a stamping die. The die assembly having a system for monitoring a gas pressure in the stamping die. The system including first and second piston-cylinder assemblies acting on a flag block wherein movement of the flag block corresponds to a pressure change. A sensor detects a movement of the flag block.