JPH0362492B

A mandrel which can be supplied with pressurised fluid is proposed for the widening of portions of a tube in order simultaneously to fix a plurality of external construction elements, such as cams, bearings or gears, with a cylindrical basic body and seal elements and distance sleeves slipped onto the latter alternately, it being possible to separate those portions of the tube which are to be widened from those portions of the tube which remain undeformed by means of the seal elements. According to the invention, the mandrel is distinguished by the fact that a device for bringing the distance sleeves closer together axially, simultaneously compressing and radially expanding the seal elements to press them against the inside of the tube, and means for limiting the axial displacement path of at least some of the distance sleeves relative to the basic body of the mandrel are provided. The mandrel thus produced makes possible simultaneous, positionally accurate widening of individual portions of the tube in exact association with construction elements slipped on, and, while being of simple structural design, makes possible better sealing than known mandrels for widening several portions while providing good stability under load of the seals and easy introduction of the mandrel into the tube.