Method for producing concrete pipes having a plastic inner pipe

A method for producing a concrete pipe which comprises a basic body made of concrete and a plastic inner pipe and which is intended for conducting a liquid, the method comprising:

• introducing a mould core into the plastic inner pipe;
• introducing the plastic inner pipe into an outer mould;
• and
• pouring concrete into an intermediate space between the outer mould and the plastic inner pipe to form the basic body made of concrete, wherein after the concrete has solidified, the plastic inner pipe remains as inner formwork in the basic body made of concrete and the mould core is removed after the concrete has at least partially solidified, and
• wherein the plastic inner pipe extends, as one continuous piece formed of a plastic film, from one end of the mould core to another end of the mould core, and the plastic inner pipe comprises a middle section and, at both ends, respective widened sections which have a larger cross section than the middle section;
• wherein the shape of the mould core is adapted to the shape of the plastic inner pipe along the entire length of the plastic inner pipe in such a way that the mould core substantially has a cross section corresponding to the cross section of the plastic inner pipe along the entire length of the mould core from one end of the mould core to another end of the mould core, wherein:
• the shape of an inner section of the mould core is adapted to the shape of the inner section of the plastic inner pipe and the inner section of the mould core substantially has a cross section corresponding to the cross section of the inner section of the plastic inner pipe,
• the shape of a wider first outer section of the mould core is adapted to the shape of the first widened section at one end of the plastic inner pipe and the wider first outer section of the mould core substantially has a cross section corresponding to the cross section of the first widened section at one end of the plastic inner pipe, and
• the shape of a wider second outer section of the mould core is adapted to the shape of the second widened section at the other end of the plastic inner pipe and the wider second outer section of the mould core substantially has a cross section corresponding to the cross section of the second widened section at the other end of the plastic inner pipe;
• wherein the mould core is formed in at least two parts and a first mould core part of the at least two-part mould core comprises the wider first outer section and a second mould core part of the at least two-part mould core comprises the wider second outer section;
• and
• wherein the plastic inner pipe has a substantially constant cross section prior to the introduction of the mould core into the plastic inner pipe and introducing the mould core into the plastic inner pipe comprises, with the introduction of the mould core, moulding of the widened sections at the ends of the plastic inner pipe by introducing the wider outer sections of the mould core.