| 摘要 |
An apparatus for molding externally ribbed and corrugated thermoplastic pipes, including a pipe die for extruding a parison of a thermoplastic material; moldblock halves circulating in endless paths and cooperating with each other to form a travelling mold; and a means withstanding the hydraulic pressure of molding. The means is represented by yokes having shanks for engagement with complimentary recesses made in the halves. The yokes are provided with rollers guided in parallel paths ensuring that the shanks are driven toward and away from the recesses in a progressive motion without changing their orientation.
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