Automatic control of extruder feed system - screw speed is varied by probe measuring melt height level in vacuum chamber

摘要

Improvement of prod. quality in the vacuum extrusion process is achieved by controlling the capacity of the extruder in relation to the melt characteristics e.g. viscosity. A probe mounted in a vacuum chamber above the screw responds to contact with the melt and signals are conveyed electrically to the screw motor drive which is varied accordingly. Input of material into the extruder is controlled by the screw speed changes. Also claimed are alternative control systems for erratic melt flow and combined smooth and erratic flow.