Non-return valve for plasticizing and injection screw comprises inner section and tubular outer section, both having sloping bores connecting when tubular section is forward, but sealed when it is back

摘要

Non-return valve (2) comprises an inner section (6) mounted in front of the screw and a tubular outer section (7) mounted around it. The central section has sloping bores (12) uniformly distributed around it which connect with similar bores (10) in the tubular section. This can slide, and preferably also rotate, to a position where it rests against a seating (17) on the front of the screw and the bores are sealed.