EXTRUSION TECHNIQUE FOR FORMING POLYMER PREFORMS, AND TUBE-FORMING TECHNIQUE

摘要

The invention relates to a tube-forming device for an extruder unit (4) or an extrusion device (1) and a tube-forming process. The tube-forming device (8) comprises at least one shaping sleeve (21a, 21b, 21c), which is designed to shape a supplied stream of polymer melt from a substantially strand-like cross section (QS) into a tubular cross section (QT). The shaping sleeve (21a, 21b, 21c) has a guiding passage (23) embedded in the sleeve wall (22), such that the guiding passage (23) is a cavity which lies within the sleeve wall (22) and, in the radial direction of the shaping sleeve (21a, 21b, 21c), is enclosed in a sealed manner with respect to the outer surfaces.