METHOD OF MAKING DOWEL JOINTS FOR TUBES Russian patent published in 2005 - IPC

FIELD: plastic working of metals, possibly manufacture of dowel joints for tubes, mainly of similar materials for U-shaped heat exchange apparatuses.

SUBSTANCE: method comprises steps of preparing tubes for welding, bending end of one tube along radius, assembling bent end of tube with reciprocal tube having rectilinear generatrix; forming non-detachable joint of tubes by means of argon-arc welding. Non-detachable joint is formed before bending by making combination type welding seam designed for plastic deforming. At forming welded joint inner annular seam is made by diffusion welding of joined tubes along butt and outer annular seam is made by surfacing additive material onto outer surface of tube butt. At assembling tubes ring of additive material is placed between them. Then tubes are subjected to axial compression until creation of contact pressure on tube ends and lateral faces of ring. Combination type joint is formed during melting additive material of ring in space of outer annular recess.

EFFECT: enhanced quality of welded joints, elimination of internal burr occurring.

8 dwg