Plasticizing injection unit with in-line screw for processing long glass fiber reinforced thermoplastics has barrier ring and restrictor ring between screw and screw head with specified flow path dimension

摘要

A cylinder(12) houses a plasticizing screw(14) of not less than100mm diameter. A screw head(20) is connected via a shaft(24) to the screw and a restrictor plate(22) lies at the rear end of the shaft. A barrier ring(26) moves along the shaft between the screw head and restrictor plate and forms a melt flow path(34) with the shaft and cylinder. The ratio of screw length to diameter(D) is 18-24 and the length of the screw feed section is 10-14 times screw diameter. Screw flight depth in the feed section is not less than13mm and in the metering section is not less than8mm. Flow path width is perpendicular to the flow direction is 3-6% of screw diameter. The angle(theta ) of the end faces of the restrictor plate(22) and barrier ring(26) to the vertical axis is 70-90[deg]. A extension(26') on the front side of the barrier ring inserts in a notch(36) in the screw head(20) and turns the barrier ring during screw rotation. Barrier ring width(W) is 0.3-0.4 times screw diameter(D).