METHOD FOR FASTENING PIPES IN PIPE GRID Russian patent published in 1997 - IPC

FIELD: plastic working of metals. SUBSTANCE: method involves forming annular beads on outer surface of pie ends; positioning pipe in pipe grid opening with annular slots till annular slots coincide with annular beads; fixing pipe from axial displacement and fastening it on pipe grid by expanding its inner surface. Annular beads are formed by applying compression force to pipe end so that depression is formed in pipe end. Prior to expansion, pipe wall with annular bead is thickened by applying compression force to stepped punch. Larger diameter step of punch is positioned in slot on pipe end without gap and smaller diameter step is positioned in pipe with gap between them, with following displacement of metal into gap. EFFECT: increased efficiency by improved localized directed plastic deformation of pipe material and improved quality of pipe grid. 2 cl, 6 dwg