Patent ID: 7517210

Claim:
An apparatus for the manufacture of compound pipes, wherein mould halves ( 2 , 2 ′), which are provided with annular mould recesses ( 33 ) and of which two at a time are combined as a pair on a moulding path ( 5 ) to form one mould, are arranged to be guided in a circuit and in a direction of production ( 6 ), wherein the mould recesses ( 33 ) are connected to partial vacuum ducts ( 35 , 35 ′) formed in the mould halves ( 2 , 2 ′), wherein an injection head ( 10 ) of at least one extruder is arranged upstream of the moulding path ( 5 ), wherein the injection head ( 10 ) is provided with an external nozzle ( 20 ) for extrusion of an external tube ( 11 ), and, arranged down-stream in direction of production ( 6 ), with an internal nozzle ( 32 ) located inside the moulding path ( 5 ) for extrusion of an internal tube ( 12 ), and with a cooling and calibrating mandrel ( 26 ) arranged downstream at a rear end of the injection head ( 10 ) in direction of production ( 6 ), wherein the mould recesses ( 33 ) have an oval cross-section with a vertical major axis ( 23 ) of a length g and a horizontal minor axis ( 24 ) of a length h, wherein the internal nozzle ( 32 ) has an oval cross-section similar to the oval cross-section of the mould recesses ( 33 ), wherein the external nozzle ( 20 ) has an approximately circular cross-section with a diameter f, with h<f<g, and wherein the external nozzle ( 20 ) is arranged at a distance e upstream of the moulding path ( 5 ) and beyond a region of collision with mould halves ( 2 , 2 ′).