Abstract
In this study, a method to facilitate the check ring closing motion by reversing or advancing the screw after the metering process was proposed for the purpose of stabilizing the injection amount of resin. Experiments were conducted on the proposed method, and it was confirmed that rotating the screw in the reverse direction resulted in good closing efficiency in the plastication of PBT, but the check ring did not completely close even when the screw was rotated in the reverse direction in the plastication of low viscosity PC. On the other hand, advancing the screw in the normal direction was found to be effective for improving the check ring closing motion and suppressing backflow in the plastication of PBT and PC. It was also confirmed that these effects are further increased when screw advancement and rotation are both performed. Furthermore, it was indicated that backflow estimation by detecting screw rotating motor load was a useful tool for optimally setting the screw reverse rotation angle when reversing screw rotation and the compression pressure when advancing the screw. Variation of the weight of the molded part was evaluated, and it was confirmed that the stability of resin injection improved remarkably with this stabilization method compared to the standard injection method without screw reverse rotation or advancement.
