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.

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.

Provided is a method for manufacturing an iron core that enables reduction of variations in dimension of a plurality of metal plates that occur during pressing of the laminate of these metal plates. The method includes: a laminate preparation step of stacking a plurality of metal plates to prepare a laminate; a pressing step of giving a temperature gradient to the laminate and pressing the laminate with a pressing machine having a punch and a die; and a temperature-gradient removal step of removing the temperature gradient from the laminate. The pressing step gives the temperature gradient to the laminate so that the temperature rises from the punch-side to the die-side in the stacking direction of the laminate.

Provided is a method for manufacturing an iron core that enables reduction of variations in dimension of a plurality of metal plates that occur during pressing of the laminate of these metal plates. The method includes: a laminate preparation step of stacking a plurality of metal plates to prepare a laminate; a pressing step of giving a temperature gradient to the laminate and pressing the laminate with a pressing machine having a punch and a die; and a temperature-gradient removal step of removing the temperature gradient from the laminate. The pressing step gives the temperature gradient to the laminate so that the temperature rises from the punch-side to the die-side in the stacking direction of the laminate.

A device for forming a sheet-metal blank, the device including: a press frame; a tool top part including an outer die and an inner die; a tool base part including a punch and a sheet-metal holder; at least one drive assigned to the tool top part and/or the tool base part; and an annular sheet-metal holder surrounding the punch and having a support face; wherein one drive is in each case assigned to the inner die on the one hand, and to the outer die and the sheet metal holder on the other hand, and the one drive displaces the inner die and the outer die at different speeds in the drawing direction. A method of forming a sheet-metal blank including: using the device during a starting period, an intermediate phase, and a final phase where the movement and/or direction of the two dies vary.

A device for forming a sheet-metal blank, the device including: a press frame; a tool top part including an outer die and an inner die; a tool base part including a punch and a sheet-metal holder; at least one drive assigned to the tool top part and/or the tool base part; and an annular sheet-metal holder surrounding the punch and having a support face; wherein one drive is in each case assigned to the inner die on the one hand, and to the outer die and the sheet metal holder on the other hand, and the one drive displaces the inner die and the outer die at different speeds in the drawing direction. A method of forming a sheet-metal blank including: using the device during a starting period, an intermediate phase, and a final phase where the movement and/or direction of the two dies vary.

To reduce warping of vertical wall portions without causing buckling occurring in a component shape not having a flange portion. A punch and a pad sandwiching a top sheet portion therebetween in the sheet thickness direction, bending blades for bend-forming the vertical wall portions, and stoppers facing the bending blades in the press direction and constraining end portions of a material to be machined are provided. The punch is supported by a first cushion component elastically expandable and contractible in the press direction. The bending blades each have an upper die component and a lower die component disposed facing each other in the press direction with an interval (D) equal to or larger than a set compression amount and a second cushion component interposed between the upper die component and the lower die component, maintaining the interval (D), and contractible in the press direction at a predetermined pressure or more. The cushion pressure of the second cushion component is lower than the cushion pressure of the first cushion component and has such cushion pressure that the second cushion component does not contract during the bend-forming of the vertical wall portions.

To reduce warping of vertical wall portions without causing buckling occurring in a component shape not having a flange portion. A punch and a pad sandwiching a top sheet portion therebetween in the sheet thickness direction, bending blades for bend-forming the vertical wall portions, and stoppers facing the bending blades in the press direction and constraining end portions of a material to be machined are provided. The punch is supported by a first cushion component elastically expandable and contractible in the press direction. The bending blades each have an upper die component and a lower die component disposed facing each other in the press direction with an interval (D) equal to or larger than a set compression amount and a second cushion component interposed between the upper die component and the lower die component, maintaining the interval (D), and contractible in the press direction at a predetermined pressure or more. The cushion pressure of the second cushion component is lower than the cushion pressure of the first cushion component and has such cushion pressure that the second cushion component does not contract during the bend-forming of the vertical wall portions.

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.