METHOD FOR MANUFACTURING WELDED STRAIGHT-SEAM PIPES OF TITANIUM ALLOYS Russian patent published in 2017 - IPC B21C37/08 

FIELD: metallurgy.

SUBSTANCE: method includes forming of a strip into a pipe blank in the form of oval cylinder, welding and calibration. Forming is performed after conventional division of strips by width into two equal parts and additional separation of each half of width into extreme sections of approximately ≤2.5 mm size and three successively arranged and approximately equal inner portions: peripheral, middle and central which are successively processed by the same forming radius R_f equal to (0.8-0.95) from the radius of the tube (R_t), in three successive stages. At the first step, the peripheral portions are bent to the fold radius R_f with simultaneous bending of edges with radius equal to (0.65-0.75) R_t, and the central and middle sections are bent with radius of back bending with a value which does not take the strip out of elastic deformations area. At the second stage gradual folding of the central sections is carried out up to the bend radius R_f, the middle sections are treated with radius which does not take the strip out of elastic deformations area. At the third stage, the middle sections are treated up to radius R_f under condition of gradual forced stretching of central and peripheral sections to radius providing an ellipse form with a larger horizontal axis in the range of 1.02÷1.1 with respect to the vertical axis at the forming mill outlet.

EFFECT: increased accuracy of geometric sizes of pipes.

3 dwg