GB691996A - Improved method of manufacturing tube bends - Google Patents

Abstract

691,996. Bending tubes. HUET, A. March 12, 1951 [March 10, 1950; July 7, 1950], No. 5899/51. Classes 83 (ii) and 83 (iv). In forming tube bends a tube is bent in successive operations over a length not exceeding that which will remain in the finished bend, each operation reducing the radius of curvature of the partly formed bend. A tube a, Fig. 2, which is to be bent through an angle of 180 degrees is first bent through 90 degrees by backing-up rolls c, c<SP>1</SP> over a rotatable former b to which it is held by a yoke d. The bent tube is then further bent to 180 degrees over a former b<SP>1</SP>, Fig. 4, by backing-up rolls c, c<SP>1</SP>, the roll c<SP>1</SP> being adjustable in position so as to engage the initially bent tube. The process may be carried out in any number of stages over formers with successively reduced diameters. Heat may be locally applied to the inner part of the bend as described in Specification 649,638, and the tube may be initially deformed to elliptical &c. cross-section in the region of bend to reduce the resistance to bending. The method may be applied to tubes of unsymmetrical cross-section in which a part of the wall is thickened and arranged in the outer part of the tube bend, the inner part being thickened during the bending process. Specification 663,427 also is referred to.