| 摘要 |
PURPOSE:To obtain a sufficient pushing-in effect, by controlling the pressing force of a hydraulic cylinder used for pushing-in a blank to a force corresponding to a forming stroke. CONSTITUTION:Relief valves 16, 17 are provided to the hydraulic pressure supplying lines 13-15 of hydraulic cylinders 11 of a blank push-in device 8, and the actuations and the pressure adjustments of these valves are performed through a controlling mechanism 20 following up a deep drawing stroke. That is, when a press head 5 is raised to press a blank 7, the mechanism 20 actuates to raise the hydraulic pressure of cylinders 11 thereby the blank 7 is pushed inside, and when the head 5 reaches a certain point, the action of the mechanism 20 is released to maintain a certain hydraulic pressure. When the head 5 is raised while maintaining this state, the mechanism 20 changes a solenoid changeover valve 18 to an I-position to reduce the hydraulic pressure. Further, when the head 5 is raised to a nearly final state of deep drawing, the mechanism 20 changes the valve 18 to a III position to release the hydraulic pressure. |
