Mixer and melter for plastics compsns. - has a cylinder and a pair of counter rotating screws one of which rotates at a lower rat thane the other

摘要

A twin-screw mixer/melter for plastics compsns. has a cylinder and counter-rotating screws inside the same, one of the screws rotating more slowly than the other one. Both screws are adapted to be longitudinally displaced wtc. the cylinder. This is achieved by means of adjusting plates arranged at one end of each screw. Each screw consists of a conveying section (I) and a discharge section (II) the former having 2 conveying thread sections with 2 or 3 thread turns with a larger pitch than the preceeding one =1 counter-directed windings an enlarged portion forming a constriction and arranged near the end of the counter-winding, and a chamfered section. The discharge section has a conveying winding adapted to improve the working-up of the moulding cpd. being processed, a discharge winding and a return winding for preventing overspill. The cylinder has a slanting surface opposite the chamfered portion of the screw, and there is a slot between cylinder and screw. The cylinder also has a discharge aperture and a degassing aperture at a point corresponding to the discharge winding. The cylinder discharge aperture and the de-gassing aperture face perpendicularly wrt. each other. The mixer/melter is a relatively simple construction and has high efficiency.