Device for producing pipes made of thermoplastic

A device for producing pipes made of thermoplastic with annular transverse profilings with a cross section in the form of undulation peaks and undulation troughs,

• with half-moulds,
• which complete one another pairwise along a straight mould section to form a closed mould, which is moveable in a motion direction, with a central longitudinal axis,
• which is transportable in the circuit counter to the movement direction of the mould to an upstream end of the mould section and
• which have an annular internal profiling, which is loadable with a partial vacuum, with a smallest internal diameter D39 to produce the transverse profiling, and
• with an extrusion tool,
• which has a nozzle support body with one of an external diameter D33 and D33′ with at least one channel for plastic melt,
• which has a nozzle with a diameter D19, which is connected by means of a channel end portion widening toward the nozzle to the channel,
• which has an inner nozzle ring and an outer nozzle ring, which between them limit the channel end portion and which are fastened to the nozzle support body,
• wherein one of the external diameter D33 and D33′ is smaller than the internal diameter D19,
• wherein the nozzle support body) in relation to the movement direction upstream of the outer nozzle ring, is covered with exchangeably attached hollow half-shells, which form a cylindrical external face with a diameter D37 and wherein a narrow annular gap with a gap width a is formed between the cylindrical external face and the internal profiling with the smallest internal diameter D39.