Extruder for foam polymer sections - which maintains final circumference of section constant from first narrow gap onwards

摘要

Extruded foam sections are produced using a cooled or heated extruder. The material passes through a narrow gap and then through a widening section in the bore of the extruder whilst it is continuously expanding, and the circumference of the section remains constant throughout allowing for the shrinkage factor. Large sections are produced without surface cracking. The internal pressure is raised to prevent premature foaming before the narrowest gap in the barrel.