Method and device for manufacturing a double-walled, thermoplastic tube with a connecting sleeve

Abstract

In at least one method for manufacturing a double-walled, thermoplastic tube with a connecting sleeve, which enables precise and complete moulding of the connecting sleeve by simple means, it is provided that a) a first tube () is extruded into a mould tunnel () comprising at least one row of moulds () guided on a path, b) the first tube () is given a corrugated shape in at least one first section and expanded into a connecting sleeve in at least one second section, c) a second tube () is extruded into the first tube and pressed against the corrugation troughs () of the first tube (), d) while the first tube () is being given a corrugated shape and the second tube () extruded into the first, the space (A) between the two tubes () is subjected to a pressure p1 that is above atmospheric pressure, e) the space (A) between the two tubes () is subjected, at a specified time before or after expansion of the first tube () into a connecting sleeve, to an essentially constant pressure p≦pabove atmospheric pressure, or to a variable, but not continuously declining pressure pf) during extrusion of the second tube () into the first tube (), which has already been expanded into a connecting sleeve, the second tube () is internally subjected to a pressure pabove atmospheric pressure and pressed against the first tube (), and g) pressure pis subsequently again applied to space (A) between the two tubes.