The tubing (2) leaving the extruder (1) is guided through the inlet opening (3) into the pre-cooling chamber (4). Here it is pre-cooled and the dosing components (6) are bonded with the wall and completely pressed onto it. The tubing is then led through a calibrator (11) and reduced to its final diameter. It then enters a main cooling chamber (12) for further cooling. The dosing components are led into the still-soft tubing using a guide track (5). They are pressed against the wall (8) by a roller which supports the wall, and by the end region (7) of the guide track.
