| 摘要 |
<p>Described is an apparatus for producing double-walled corrugated pipes (72) comprising an extrusion nozzle (12) and a cooling mandrel (14) which protrude into a molding passage (16) formed by corrugator molding jaws (18, 20). The extrusion nozzle (12) has a first annular nozzle opening (34) for delivering an outer shell (62) and a second annular nozzle opening (40) for delivering an inner shell (64). The outer shell (62) delivered from the first annular nozzle opening (34) is sucked in the molding passage (16) by means of a vacuum against the corrugated transversely ribbed inner surface (66) of the corrugator molding jaws (18, 20). In order to prevent a reduced pressure which thereby acts on the inner shell, that is to say to prevent a pressure difference between the inside and the outside of the inner shell (64) which issues from the second annular nozzle opening (4), the extrusion nozzle (12) has at least one first and at least one second venting hole (74) and (76) which are in fluid communication with the atmosphere surrounding the apparatus.</p> |
