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

FIELD: plastic working of metals, possibly manufacture of dowel joints of tubes, mainly of different 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 and forming non-detachable joint of tubes by means of argon-arc welding at using additive material; forming non-detachable joint before bending operation by making combination type welded joint; subjecting combination type welded joint and zones near it to plastic deforming; forming inner seam by diffusion welding of joined tubes and additive material along butt and forming outer seam by surfacing additive material onto outer surface of tube butt. At assembling ring of additive material with stepped inner profile is placed between tubes. Then tubes are axially compressed for achieving contact pressures on ends of tubes and on lateral faces of ring. Combination joint is formed at melting additive material of ring in space of outer annular recess. Plastic deforming of joint and zones near it is realized by double straightening of tube.

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

8 dwg