Patent ID: 6250128
Filing Date: 2001-06-26
Classification: B21J,B21K

Abstract:
A forging die device for upset-forging a raw material that is being filled in a cavity of a lower molding die at a portion between an upper punch of an upper molding die provided on a slide and a lower punch of the lower molding die provided on a bolster,wherein said upper and lower punches are provided with an upper pin and a lower pin respectively so that a first end of each pin is protruded and withdrawn from each of end surfaces of said upper and lower punches and said pins are vertically movable in the upper and lower punches respectively, while a second end of said upper and lower pins is applied with a back-pressure by a back-pressure imparting means;wherein said back-pressure imparting means comprises:hydraulic cylinders that apply the back-pressure to the upper and lower pins utilizing hydraulic oil,a hydraulic oil supply that supplies the hydraulic oil to the hydraulic cylinders, anda solenoid valve that shuts off and communicates a circuit between the hydraulic cylinders and an oil tank;wherein said back-pressure imparting means imparts the back-pressure to each of said upper and lower pins by causing the hydraulic oil supply to supply the hydraulic oil to the hydraulic cylinders at a time of a molding operation; andwherein said back-pressure imparting means removes the respective back-pressures by switching the solenoid valve to take a communicating position to discharge the hydraulic oil to the oil tank just before said cavity is completely filled up with the raw material.