Process and device for cooling hollow profiles, especially pipes or tubes, of thermoplastics during extrusion

摘要

Hollow profiles, especially pipes or tubes, manufactured by extrusion of thermoplastics are subjected to both an external cooling and an internal cooling during the extrusion process in order, on one hand, to avoid thermal damage to the material structure and, on the other hand, to prevent, but at least to reduce, internal stresses within the profile walls. The hollow profile is cooled after emerging from the extruder head, on the one hand, externally by the sizing sleeve and following this by sprayed water and, on the other hand, from the inside by means of an extended region delimited by the extruder head and a plug system and fed with cooling water. In the hollow profile 2, upon emergence from the extruder head 1, the cooling water is sprayed in such a manner that it evaporates due to the effect of the material temperature at least in the effective range of the sizing sleeve 3 adjacent to the extruder head 1, whilst adjacent to this the vapour condenses on the externally cooled, colder areas of the extended region, which is delimited by the plug system 8, on the inner side of the hollow profile walls.