| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently exhaust gas in a metering zone by continuously forming a degassing groove of a predetermined lateral width on a top surface of a flight to a site disposed near a material dropping port of a cylinder at the time of mostly retracting a screw from an end of the screw. SOLUTION: The screw for a thermoplastic resin comprises a flight 3 continuously formed from an end of the screw to the vicinity of a rear end on a periphery of a shaft 2. A degassing groove 4 is continuously formed on a top surface of the flight 3. The screw 1 in a heating cylinder has a clearance for slightly rotating and sliding for a difficulty of an invasion of a molding material even in a molten state between the top surface of the flight 3 and an inner wall surface of the cylinder. In this case, the groove 4 communicates with any of a supply zone, a compressing zone and a metering zone in the cylinder via the clearance, and communicates with an exterior via a material dropping port or a gap of a periphery of the rear end of the shaft 2. |
