| 摘要 |
PURPOSE:To remove necessity to supply hydraulic oil by sucking the same, by so constituting that the pressure of a large-diameter extending chamber does not turn negative in a manner wherein a pressure receiving area of the large-diameter extending chamber and that of a large-diameter contracting chamber are made identical with each other and the hydraulic oil is circulated at the time of extension of a large- diameter piston. CONSTITUTION:A two rod type large-diameter piston 54 is inserted into a large- diameter cylinder tube 52, through which a large-diameter extending chamber 55 and large-diameter contracting chamber 56 whose pressure receiving areas are identical with each other are formed. A small-diameter contracting chamber 60 is formed by a small-diameter piston 59 by ejecting a rod 58 into a small-diameter cylinder tube 53, and a small-diameter extending chamber 63 is formed by inserting a pipe 62 into a blind hole 61. At the time of mold clamping, discharge hydraulic oil of a pump P is supplied to the extending chamber 63 by making an operation valve 66 into an extended position I, the contracting chamber 60 is connected with a drain, and a piston 54 is extended at a high speed. In this instance, an operation valve 65 is at a neutral position N, the extending chamber 55 and contracting chamber 56 are connected with each other, pressure of the extending chamber 55 does not turn negative and the piston 54 is extended smoothly. |
