| 摘要 |
PURPOSE:To improve the accuracy of change-over point to dwell while preventing the growth of the shock pressure within a cavity, and enabling the product with a stabilized accuracy to be manufactured by interposing the braking circuit capable of being changeable in the back pressure of an injection cylinder during the advance period of an injection screw to a back pressure side circuit. CONSTITUTION:When a compression process comes nearly to the end, a switch-over electromagnetic valve 27 is put in an ON-position, and shifted to an I position so as not to generate a shock pressure Ps within a cavity 1, so that an oil conduit 25 is closed, and the back pressure set by a relief valve 24 is generated to the oil within the chamber 22c of a cartridge valve 22, so that a braking force is applied to a back pressure side chamber 8b. It is most preferable for the timing in shifting ON that each position of injection piston screws 9, 7 is put ON immediately before the change-over point to the dwell. When the detecting pressures by the signal of detecting sensor 32 of the pressure within the cavity for detecting this timing and by the signal of a detecting sensor 33 of an injection oil pressure are compared with the pressure set previously, and reach the set value, or when a position detector 40, which is rotated by the shift of injection piston screws 9, 7, reaches the predetermined position, these conditions are detected and the switching-over electromagnetic valve 27 is put to an 'ON' position. |
