| 摘要 |
A device for continuously manufacturing a plastic tube with helical grooves comprising an extruder with an annular nozzle situated between a casing and a core, and two rows of mould halves, each row being movable along endless guide paths extending parallel to each other in an operative track, opposite mould halves in this track completing one the other by their mould cavities so as to form a hollow mould, the core of the annular nozzle being provided with a continuous bore for introducing a gaseous pressure between the annular nozzle and closing means consisting of a number of discs of flexible material, whereby the discs have a diameter such that helical grooves are closed when a plastic tube is provided with grooves in the moulds.
|
