Adjustable sizing head for extruding plastic pipes includes air pressure chamber to reduce diameter of emerging extrudate

摘要

The extruded pipe emerging from the extruder enters a pressure chamber (30) supplied with air (5) at a higher pressure than exists within the pipe so that the outer diameter of the extrudate can be adjusted. The pipe (10) is then cooled in a vacuum sizing bath (4) and emerges through a vacuum seal (9).