An actuator assembly for a redraw sleeve that operates independently of the ram drive mechanism is provided. The actuator assembly utilizes a servomotor. The servomotor is structured to provide its output shaft with a variable rotation speed so as to accommodate the need for the redraw sleeve to be in selected locations at specific times.

The die cushion device according to the present invention includes a first hydraulic cylinder and a second hydraulic cylinder that are independently and simultaneously controlled. When a cushion pad is pre-pressurized, pressure control is performed on the first hydraulic cylinder via a first hydraulic circuit so that a pressure in a lower chamber of the first hydraulic cylinder is pre-pressurized to a preset pressure, and position control is simultaneously performed on the second hydraulic cylinder via a second hydraulic circuit so that the cushion pad is held in the die cushion standby position. A force with which the first hydraulic cylinder moves the cushion pad upward is balanced with a force with which the second hydraulic cylinder moves the cushion pad downward (a force for holding the die cushion standby position).

The die cushion device according to the present invention includes a first hydraulic cylinder and a second hydraulic cylinder that are independently and simultaneously controlled. When a cushion pad is pre-pressurized, pressure control is performed on the first hydraulic cylinder via a first hydraulic circuit so that a pressure in a lower chamber of the first hydraulic cylinder is pre-pressurized to a preset pressure, and position control is simultaneously performed on the second hydraulic cylinder via a second hydraulic circuit so that the cushion pad is held in the die cushion standby position. A force with which the first hydraulic cylinder moves the cushion pad upward is balanced with a force with which the second hydraulic cylinder moves the cushion pad downward (a force for holding the die cushion standby position).

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.

In a press machine having a die cushion device which supports a cushion pad and which generates a die cushion force when a slide of the press machine is lowered, the wrinkle generation detection device includes: a slide position detector which detects a height position of the slide; a cushion pad position detector which detects a height position of the cushion pad; and a computing unit which consecutively calculates a deviation between the height position of the slide detected by the slide position detector and the height position of the cushion pad detected by the cushion pad position detector, during a time period from the start of forming of a material by the slide lowering to the end of the forming, wherein a wrinkle generated in the material is detected based on an increase of the deviation consecutively calculated by the computing unit.

In a press machine having a die cushion device which supports a cushion pad and which generates a die cushion force when a slide of the press machine is lowered, the wrinkle generation detection device includes: a slide position detector which detects a height position of the slide; a cushion pad position detector which detects a height position of the cushion pad; and a computing unit which consecutively calculates a deviation between the height position of the slide detected by the slide position detector and the height position of the cushion pad detected by the cushion pad position detector, during a time period from the start of forming of a material by the slide lowering to the end of the forming, wherein a wrinkle generated in the material is detected based on an increase of the deviation consecutively calculated by the computing unit.

An actuator assembly for a redraw sleeve that operates independently of the ram drive mechanism is provided. The actuator assembly utilizes an eccentric journal coupled to a drive shaft of a servomotor. The servomotor is structured to provide its output shaft with a variable rotation speed so as to accommodate the need for the redraw sleeve to be in selected locations at specific times. Further, the redraw sleeve includes a collapsing redraw cylinder to allow the redraw sleeve to dwell in a forward position.

A method for press forming an automotive outer panel includes: providing an elastic body to a punch such that the elastic body abuts against a metal sheet away from a portion corresponding to a character line in the metal sheet; abutting a contact surface portion of the protruding elastic body against the metal sheet; and forming the character line with the ridgeline and the valley line by relatively moving the die toward the punch while abutting the contact surface portion against the metal sheet to deform the elastic body such that the elastic body becomes flush with the punch-side forming surface portion at a bottom dead center of forming. A protrusion amount of the elastic body from the punch-side forming surface portion is set such that the elastic body contacts the metal sheet before the ridgeline contacts the metal sheet to cause the metal sheet to become plastically deformed.

A method for press forming an automotive outer panel includes: providing an elastic body to a punch such that the elastic body abuts against a metal sheet away from a portion corresponding to a character line in the metal sheet; abutting a contact surface portion of the protruding elastic body against the metal sheet; and forming the character line with the ridgeline and the valley line by relatively moving the die toward the punch while abutting the contact surface portion against the metal sheet to deform the elastic body such that the elastic body becomes flush with the punch-side forming surface portion at a bottom dead center of forming. A protrusion amount of the elastic body from the punch-side forming surface portion is set such that the elastic body contacts the metal sheet before the ridgeline contacts the metal sheet to cause the metal sheet to become plastically deformed.