SETT OCH ANORDNING ATT FORMA ETT INVENDIGT, RINGFORMIGT SPAR I EN PLASTRORDEL

摘要

A socket of a thermoplastic pipe is provided with an internal groove by subjecting the tube to an upsetting action and simultaneously inflating the tube by an inner pressure. Subsequently a moulding ring is expanded and the tube is shrunk onto the expanded ring by cooling. Before shrinkage the inner diameter of the bottom of the groove is at least equal and preferably greater than the outer diameter of the moulding ring in expanded form.