METHOD FOR PRODUCING CONVERSION STRAIGHT-SEAM TUBE BLANK FROM TITANIUM BASE ALLOYS FOR ROLLING COLD ROLLED LARGE AND MEAN DIAMETER TUBES WITH IMPROVED ACCURACY OF WALL GEOMETRY Russian patent published in 2007 - IPC B21C37/08 B23K5/02 C21D9/08 

FIELD: rolled tube production, namely processes for making conversion tube blank for rolling cold-rolled large and mean diameter tubes from titanium base alloys with improved accuracy of their wall geometry, possibly in lengthwise welding mills and in other mills with use of conversion tube blank.

SUBSTANCE: method comprises steps of planing sheet along its width; preparing edges of sheet blank to welding; shaping sheet blank in rollers for producing tube conversion blank for rolling large diameter tube; welding lengthwise edges of blank on moving copper shoe in argon gas shield atmosphere by means of consumable electrode of the same kind of alloy at reinforcing outer and inner seams. Sheet blank edges to be welded are in the form of blunted broken line. Geometry size of said broken line are determined according to expressions: A= S/3; C = (0.35 - 0.45)S; D = (B - C)/2; D' =(B'- C)/2; K = K' = A = S/3 where S - wall thickness of sheet blank, mm; A - blunting value of welded edges, mm; C - gap value between welded edges of sheet blank, mm; D - width of edge dressing for welding outer seam, mm; D' - width of edge dressing for welding inner seam, mm; K = K' = A - thickness value of edge dressing of outer and inner seams, mm. Welding process is realized on copper shoe at accuracy of assembling edges ± 0,5 mm. Roots of inner seams are fused by means of non-consumable electrode in argon gas shield atmosphere. Geometry size of welded seams are determined according to expressions: B = 30 - 35 mm; B' = 25 - 30 mm; H = (0.1 - 0.2)8; H' = (0.05 - 0.1)S where B - width of outer seam of conversion tube blank, mm; B' - width of inner seam of conversion tube blank, mm; H - reinforcement of outer seam of conversion tube blank, mm; H' - reinforcement of inner seam of conversion tube blank, mm. Invention allows produce high quality tubes according to ASTM B 862 -02 from welded conversion tube blanks.

EFFECT: lowered labor consumption of production of high quality tubes from conversion welded tube blanks, reduced factor of alloy consumption of conversion of straight-seam conversion tube blank to cold rolled tube, lowered cost of cold rolled tubes of titanium alloy base.

4 cl, 1 dwg, 1 tbl