Abstract: A method and a circulating-air furnace for heating one end of a length of plastic pipe for the purpose of belling the end of the pipe. The circulating air is made to flow through a fan and a heater and thereinafter along the outer and inner faces of the pipe end. In order to improve the adjustability of the heating of the pipe end, the circulating air is blown as an annular shaped flow in the direction of the center axis of the pipe end towards the pipe end so that the air flow is divided onto the inner and outer faces of the pipe.

Abstract: A device for producing expansions and in particular inside grooves, such as packing grooves, in plastics pipes and pipe components. The device comprises a form ring for shaping the inside profile of the expansion, the circumference of which ring is divided into two groups of segments, which can be shifted radially inwards so that the form ring can be disassembled and removed from the pipe after shaping of the expansion, a mandrel that can be shifted axially through the form ring, a core body that surrounds the mandrel and in relation to which the mandrel can be shifted axially, and two groups of first inclined faces, in connection with the mandrel, one face group for each segment group, so as to produce radial movement of the segments, for example by forcible controlling, whereby the first group of inclined faces is arranged axially at a distance from the second group of inclined faces.