Verfahren zur Herstellung von Rohrleitungsverbindungen aus Polyolefin

摘要

Pipes are joined in a process in which one end of a polyolefin pipe is expanded and fitted over a connecting piece. The end, whose i.d. is smaller than the o.d. of the connector, is reversibly expanded at room temp. by means of a spreader mandrel to an i.d. greater than the o.d. of the connector; the spreader is removed and the pipe and connector are fitted together, after which the connector is attached formly to the pipe by reversing the expansion. Medium density and crosslinked polyolefins in partic. are cold formed and they tend to revert to their original shape. The expanded pipe therefore shrinks back again. It does so relatively quickly. Moreover the shrinkage causes the polymer to adapt itself to such features as beads, dimples, grooves etc.. Clamping ring of such reversibly formed polymer can also be fitted over the end of the pipe in the same way. Equally an e.g. metal clamping ring is used conventionally. ADVANTAGE - Produces tight joints at room temp..