METHOD FOR FASTENING TUBE IN TUBE WALL Russian patent published in 1997 - IPC

FIELD: plastic metal working, namely, processes for fastening tubes in tube walls by local oriented plastic deformation of tube material. SUBSTANCE: method for fastening tube in tube wall comprises steps of forming annular protrusions on outer surface of tube ends, placing tube into wall with annular rectangular cross section recesses at matching protrusions and recesses, fixing tube against axial motion and securing it to tube wall by applying axial compression effort to it at side of inner surface of tube. Annular trapezoidal cross section protrusions are formed on end portions of tube at simultaneously sizing its opening due to placing onto end of connectable die with annular trapezoidal recesses disc made of elastic material. Disc is placed coaxially relative to opening; diameter of its own opening exceeds that of die opening . Tube is placed in such a way that its end is laid in plane of free end of disc. Then tube is fixed against axial motion and loaded by axial compression effort on part of its cross section area by means of stepped punch in order to realize successive expansion of tube until diameter of disc opening. At final stage tube is trimmed along line laying in plane of mutual contact of ends of disc and die; then tube material is pressed in between d disc and large step of punch for completely filling annular recesses and separating tube in trimming plane. Tube separation is performed by rotating ring of elastic material relative to its axis or by moving stepped punch in direction opposite relative to its motion direction at tube separation. EFFECT: enhanced reliability of tube fastening. 3 cl, 3 dwg