DEVICE FOR FORMATION OF BELL MOUTHS ON TERMINAL CONNECTING SECTION OF PIPES OF THERMOPLASTIC MATERIAL

摘要

FIELD: device for formation of bell mouths having a stable shape with an even inner surface on the terminal connecting section of pipes of preheated thermoplastic material. SUBSTANCE: the device has a part for a preliminary action, the first and second parts. The part for preliminary action includes a hollow rubber member that can be freely inserted inside the terminal section of the pipe and inflated for preliminary formation of the first bell mouth. The first part has mechanical sectors transferred radially from the first extreme pulled-in position, in which the first part can be freely inserted inside the terminal section, to the second extreme separated position, in which the diameter of the first part exceeds the diameter of the first bell mouth, for formation of the precise temporarily expanded bell mouth. The second part has a permanent bell mouth. The second part has a permanent geometric form and is positioned behind the first part. The diameter of the second part equals the nominal and final inside diameter of the finally formed bell mouth. The parts of the device make up a gang mandrel executing several operating phases. With the aid of the mandrel first a bell mouth is preliminarily formed, whose diameter exceeds the nominal diameter and on whose surface there are no roughnesses. The mentioned bell mouth, partly expanded for preliminary action, is then expanded with the aid of the first part, after which it is spontaneously compressed and calibrated in the second part with attainment of the nominal diameter. EFFECT: produced bell mouths having a stable shape. 8 cl, 5 dwg