Patent ID: 7104775
Filing Date: 2006-09-12
Classification: B29C

Abstract:
1. An injection unit having a rotatable device for preventing reverse flow, the injection unit comprising: an injection screw rotatably mounted inside a cylindrical barrel to inject resin into the cylindrical barrel therethrough; a spacer mounted at an end portion of the injection screw, the spacer rotating integrally with the injection screw and having at least one or more first flow channels arranged on the circumferential surface thereof at predetermined intervals; a screw head perforating the spacer and rotatably supported on the injection screw, the screw head having at least one or more second flow channels arranged on the circumferential surface thereof at predetermined intervals and corresponding to the first flow channels; spring means mounted at an end to the injection screw and mounted at the other end to the screw head, the spring means elastically accumulating a repulsive force when the injection screw rotates and being elastically restored to an original position when the rotation of the injection screw stops; and channel phase control means for rotatably connecting the screw head relative to the spacer, so that the phase of the first flow channels corresponds to the phase of the second flow channels by being rotated in the first direction when the injection screw rotates, and the phase of the first flow channels is discordant to the phase of the second flow channels by being rotating in the second direction, which is the opposite direction of the first direction, when the rotation of the injection screw stops.