Fabrication de cintres de tubes

摘要

973,133. Making tube bends; bending; forging. BABCOCK & WILCOX Ltd. Feb. 4, 1963 [Feb. 7, 1962], No. 4396/63. Headings B3A, B3E, B3H and B3Q. A method of making steel tube bends having a small radius of bend comprises forming a bend of large radius, heating the median part of the bend, holding the rectilineal branches by respective jaw members and giving the jaw members relative motion normal to the transverse plane of symmetry of the bend to effect a compression of the heated region which at least initially is free of contact with any surfaces of support or compression. A tube bend of relatively large radius is heated in the region ABCD and placed between two parallel plates 4, 6 each formed in two parts 41, 411 and 61, 611 positioned by bands 8 to leave a central free space 10. Rectilineal branches 21, 211 of the bend are held by jaws 14, 16, each in two parts 141, 1411 and 161, 1611, which are then moved towards one another in the direction G to deform the bend, thickening the inner and outer bend walls as shown in Fig. 3. A heated neutral gas under pressure may be passed into the tube towards the end of the compression to apply the soft parts of the outside of the bend to contours 24, 26 of the jaws 14, 16. The region ABCD may be heated by a ring of jets during compression. A rib may be formed on the bend between the upper parts 28, 30 of the jaws 14, 16. Grooves may be provided in the jaws 14, 16 to enable ribs to be formed by pressing metal in the grooves. In an alternative arrangement, Fig. 6, plates 4A, 6A are each in one part but are hollowed out at 22 so that the bend 2A may swell freely; bends of 120 degrees may be worked as above.