Injection apparatus

Abstract

In an injection apparatus, a first cylinder and second cylinder for driving an injection cylinder connected to an injection plunger are connected in parallel with each other with respect to the injection cylinder. A piston of the first cylinder and a piston of the second cylinder are synchronously driven by driving means. A directional control valve and flow rate adjustment circuit are provided between one end of the injection cylinder and one end of the first cylinder.

1 . An injection apparatus, comprising:
 an injection cylinder driving an injection plunger to inject a molding material;   a first cylinder connected to the injection cylinder, the first cylinder feeding hydraulic oil to the injection cylinder and draining hydraulic oil therefrom;   a second cylinder connected to the injection cylinder in parallel with the first cylinder, the second cylinder feeding hydraulic oil to the injection cylinder and draining hydraulic oil therefrom;   a single unit of driving means for reciprocatingly driving a piston of the first cylinder and a piston of the second cylinder;   a directional control valve provided between one end of the injection cylinder and one end of the first cylinder, the directional control valve allowing a flow of hydraulic oil from the first cylinder toward the injection cylinder but cutting off the flow of hydraulic oil from the injection cylinder toward the first cylinder;   flow rate adjustment means provided between the directional control valve and the first cylinder, the flow rate adjustment means being for adjusting a flow rate of hydraulic oil between the one end of the first cylinder and the one end of the injection cylinder, and   wherein the driving means drives the piston of the first cylinder and the piston of the second cylinder in synchronization with each other.   
     
     
         2 . The injection apparatus according to  claim 1 , wherein the flow rate adjustment means includes:
 a buffer tank capable of temporarily storing hydraulic oil;   a pilot switching valve capable of discharging to the buffer tank the hydraulic oil present between the directional control valve and the first cylinder; and   a replenishment control valve supplying the hydraulic oil in the buffer tank between the directional control valve and the first cylinder when there is insufficient hydraulic oil between the directional control valve and the first cylinder.   
     
     
         3 . The injection apparatus according to  claim 1 , wherein a cylinder diameter of the first cylinder is greater than that of the second cylinder.