TWI773919B

The present disclosure relates to a screw of an injection molding machine in which a heating cylinder is formed with a first compression section, a starvation section, and a second compression section, and in which an inert gas is to be introduced into the starvation section. At a portion of the screw corresponding to the first compression section, a barrier flight as a double flight including a combination of a main flight and a sub-flight having a lead angle larger than that of the main flight is formed, and a dam flight having a predetermined-width ring shape is formed, downstream of, i.e., in front of the barrier flight. A seal structure to prevent backflow of the resin may be provided between the dam flight and the starvation section.