ROLLER TYPE EXPANDING TOOL FOR DIFFUSION WELDING OF DIFFERENT-KIND LARGE-DIAMETER TUBES Russian patent published in 2002 - IPC

FIELD: welding of large-diameter tubes. SUBSTANCE: expanding rollers are arranged by two rows. First row includes centering rollers of the same diameters; circle described around said rollers has diameter equal to initial diameter of expanded tube. Second row of rollers includes working rollers with different diameters spaced by different distance from tool body. Working roller with minimum diameter is spaced by the largest distance; working roller with maximum diameter is spaced by the least distance. Centering rollers are cylindrical ones; they have inlet cone chamfer on outer end. Expanding rollers are changeable ones. Tie rods have the same length and configuration. Working rollers are fixed at different distance relative to tool body by means of spacing washers. On tool body at side of tie rod with expanding rollers heat insulation screens made of polished plates are mounted. EFFECT: improved design of tool providing its increased useful life period due to uniform expanding process and due to protection of bearing assemblies against overheating. 5 cl, 1 dwg