Method and Device for Heating an End Section of a Plastic Pipe

A method for heating an end section of a plastic pipe (1) for preparing to form a sleeve on the plastic pipe, wherein the end section can be heated on the exterior by means of external heating jaws (2, 3) and in the interior by means of a heating mandrel (4) that can be inserted into the plastic pipe (1), so that it can be heated to the deformation temperature of the plastic pipe or higher, characterized in that the heating of the internal end section of the plastic pipe is accomplished by means of a heating mandrel (4) having at least one first length section (6) and one second length section (5), such that the diameter of the heating mandrel (4) along the first forward length section (6) is selected to be smaller than the internal diameter of the end section of the pipe;

• the diameter of the heating mandrel (4) increases over the second length section (5), which is connected to the first length section (6), toward the end of the heating mandrel (4), such that the end of the second length section (5) comes in contact with the interior of the end section of the pipe on heating of the internal end section of the pipe, so that, when heated, the end of the end section of the pipe to be heated comes in contact with the external heating jaws (2, 3) as well as the heating mandrel (4);
• and after heating the end section of the plastic pipe (1), the heating mandrel (4) is removed from the plastic pipe before the sleeve is formed.