| 摘要 |
A device for manufacturing a plastic tube with transverse or helical grooves comprised of an extruder, and a die consisting of two movable halves forming a mold cavity with a ribbed profile through which the tube is extruded. The halves of the die are each provided with semi-circular elongated heating elements or members for heating a region between the opening of the extruder and the beginning of the die forming the mold cavity. One embodiment of the present invention uses an inflatable member disposed interior to the tube which when inflated forces the tube outwardly causing portions of the tube to conform to the grooves in the mold cavity to form a ribbed profile in the tube. The inflatable member comprises a movable cylinder having an inflatable wall and two expandable spaced apart end discs. Another embodiment of the present invention comprises an inflating member having two spaced apart expandable closing discs which, when expanded, communicate with the interior wall of the plastic tube thus, creating a high-pressure chamber therein. A spring-loaded valve for controlling the ingress and egress of the inflating medium, such as compressed air, into and out of the pressure chamber is situated between the two closing discs. The inflating medium trapped in the chamber under high pressure exerts a force on the tube thus, displacing portions of the tube into the ribbed profile in the mold cavity to form transverse or helical grooves in the tube.
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