Backflow prevention device for in-line screw type injection molding machine

摘要

A screw tip is provided in front of a screw with a shaft interposed therebetween, and a check ring is fitted around the shaft. The check ring is separated from a front end portion of the screw when the screw is rotated in a forward direction. The check ring contacts the front end portion of the screw when the screw is advanced. A front end surface of the check ring is provided with teeth, and a rear end surface of the screw tip is provided with grooves with which the respective teeth are engaged. Respective one side surfaces of the grooves and the teeth which are pressed against each other when the screw is rotated in the forward direction are formed vertical to the front end surface of the check ring, and side surfaces thereof located on the reverse sides of the above respective one side surfaces are inclined.