FORFARANDE FOR FRAMSTELLNING AV ETT VERME- OCH LJUDISOLERAT LEDNINGSROR

摘要

Using an extruder die (1), in the process an outer pipe (2) made of thermoplastic is extruded coaxially to an inner pipe (6) fed continuously over a guide pipe (5). Then, using a mixing device (9), a reactive foam composition (11) forming the heat-insulating layer is introduced by means of a mixing device (9) into the annular space between the inner pipe (6) and the outer pipe (2). This foam composition (11) is sprayed onto a conveyor belt (7) running off from a supply reel (8). The foam composition (11) is formulated such that it does not fill the annular space until the outer sheath (2) has sufficient strength. The extruded outer pipe (2) is calibrated in a subatmospheric pressure chamber (3) partly filled with water and intensively cooled in a second chamber (4). The film used hitherto for forming a mould cavity for the insulating layer and the forming device for this film are dispensed with.