TUBE JOINT FORMING METHOD Russian patent published in 2006 - IPC B21C37/28 B21D53/02 B23K9/16 

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

SUBSTANCE: method comprises steps of preparing tubes to welding, bending end of one tube by radius; assembling said end of tube with reciprocal tube and forming non-detachable tube joint. Said joint is created before bending by forming combination type welded seam and then performing plastic deforming of seam and near-seam zones. Inner annular seam is formed by diffusion welding of tubes along butt. Outer seam is formed by welding additive material onto outer surface of tube butt. At assembling ring of additive material is placed between tubes in outer annular recess preliminarily formed by profiling tube end portions. Then tubes are axially compressed in order to provide contact pressure on ends of tubes and on lateral faces of ring. Combination type seam is formed at fusion of additive material of ring. Plastic deforming of seam and near-seam zones is realized by double straightening of tube due to imparting to it rotation and translation motion. Tube end portion before welded seam is rotated at larger angular velocity than end portion of tube behind welded seam.

EFFECT: possibility for providing desired quality of welded seams, elimination of inner burr formation.

8 dwg