METHOD FOR PRODUCING CONVERSION TUBE BLANK FOR ROLLING COLD ROLLED LARGE- AND MEAN-DIAMETER TUBES OF TITANIUM BASE ALLOYS Russian patent published in 2006 - IPC B21B3/00 B21C37/08 B21B23/00 B23K101/06 

FIELD: rolled tube production, namely processes for producing conversion tube blanks for rolling cold rolled tubes of large and mean diameters of titanium base alloys, possibly in mills for lengthwise welding.

SUBSTANCE: method comprises steps of producing sheet blank, planing sheet along its width, preparing sheet edges for welding, forming sheet to tube blank and welding lengthwise edges on copper block by means of consumable electrode of the same kind of alloy in protective argon atmosphere while providing growth of outer seam 0.5 -1.5 mm, growth of inner seam no more than 1.0 mm. On copper block along axis of welded joint recess is formed whose geometry sizes are similar to those of inner seam growth contour. Root of inner seam is remelted by means of non-consumable electrode in argon protective atmosphere. Using grinding tool or cutter whose cutting edge is in the form of arc exceeding outer circle of tube blank, part of seam growth and layer of thermal influence zone are removed from outer seam and zone of thermal influence while providing smooth transition to base metal. After remelting inner seam, growth of said seam and layer of thermal influence zone are removed by means of grinding tool or cutter whose cutting edge is in the form of arc being less than inner circle of tube blank while providing smooth transition to base metal. Geometry sizes of removed layer of outer seam are determined according to expressions: B = (1.5-1.8)S, A = (0.07-0.10)S. Geometry sizes of removed layer of inner seam are determined according to expressions: B₁ =(1.2 -1.6)S, A₁ = (0.08 -0.11)S where B - width of removed layer of outer seam and thermal influence zone, mm; A - thickness of removed layer along center of outer seam, mm; S- wall thickness of conversion electrically welded straight-seam tube blanks, mm; B₁ - width of removed layer of inner seam and thermal influence zone, mm; A₁ - thickness of layer removed along center of inner seam, mm. Larger values of coefficients refer to conversion tubes with less thickness of walls. Invention provides reduced factor of alloy consumption for conversion "straight seam conversion tube blank - cold rolled tube".

EFFECT: high-quality tubes produced of welded conversion tube blanks instead of seamless ones, lowered labor consumption for making tubes, reduced cost of cold rolled tubes of titanium base alloys.

6 cl, 1 tbl