| 摘要 |
PURPOSE:To eliminate overloading during forging and to prevent the failure of dies, by making the flowing of working fluid into and out from a lower cylinder free and placing a crank pin via a wrist pin on a piston. CONSTITUTION:When a solenoid valve 15 of a hydraulic circuit is set at (b) in a crank press, pressure oil is supplied into a lower cylinder 9, and a slide 2 is moved downward by the force for pressing a crank pin 4 generated with a lower wrist pin 8 from a piston 10. The oil in an upper cylinder 6 returns to a pneumatic-hydraulic converter 12. When the valve 15 is set neutral and a crank shaft 3 is rotated, pressurizing force is generated in the slide 2. When the slide 2 is overloaded, a relief valve 16 is opened to limit the pressurizing force. The valve 15 is set at (a) upon passage of the shaft 3 through the bottom dead point, then the pressure oil flows into the cylinder 6, and the oil in the cylinder 9 returns into a tank 20, thus forcing the slide 2 to move upward. The shaft 3 stops at the top dead center after rotating once and one cycle is completed. |
