Apparatus for the continuous production of pipes with cross-profiled walls

In apparatus for the continuous production of pipes with cross-profiled walls from a pipe strand of thermoplastic plastic emerging in still plastic state from an extrusion nozzle comprising

• two sequences, moving in endless paths, of mould halves which run adjacent each other along a straight working section following the extrusion nozzle and complement each other in pairs to form a travelling hollow mould for the profiling of the tube walls,
• and a return means which for each of said sequences at the end of the working section moves the arriving mould halves transversely of the working section apart into positions adjacent the end of the working section, then conveys the mould halves back to positions adjacent the start of the working section in a state not joined together within the sequence by means of return conveyors extending along the working section spaced from the latter and places them there again at the start of the hollow mould, and a plurality of mould halves of each sequence may be disposed simultaneously in the return conveyor,
• the sequences of mould halves circulating guided on a horizontal base and the return means having for each mould half sequence separate transverse conveyor means at the start and end of the working section to convey the mould halves for each of the sequences from the position adjacent the start of the working section to the start of the hollow mould and from the end of the hollow mould into the position adjacent, the end of the hollow mould, the improvement wherein
• the conveyors each comprise beneath the mould half path an endless pulling member having a run circulating in the conveying direction of the respective conveyor,
• that the pulling members carry drivers which at the start of the conveying path come into engagement with the mould halves entrain the latter and at the end of the conveying path come out of engagement with the mould halves again,
• that the mould halves in the region of the return means are moved in spaced relationship with each other,
• and that guide elements are provided for parallel guiding of the mould halves in the region of the return means.