Method for making curved tubes

Claim 1

A method of constructing a curved tube comprising the steps of forming a first wall section by deforming a first sheet to form an elongated substantially semicylindrical element having laterally spaced cheek regions extending longitudinally along its opposite sides, and draw bending said semicylindrical element by clamping an end region thereof against a rotatable form having a channel extending in a sweep thereabout which channel substantially matches in cross sectional profile the cross sectional profile of said semicylindrical element and then rotating such form to bend the element to conform to the curve of said sweep along the longitudinal axis thereof with drawing of the element across a shoe which confines said element in said channel with such confinement introductory to the bending of the element, the cheek regions in said first wall section facing inwardly toward the axis about which the wall section bends, forming a second wall section by deforming a second sheet to form another elongated substantially semicylindrical element having laterally spaced cheek regions extending longitudinally along its opposite sides and draw bending said other semicylindrical element by clamping an end region thereof against a rotatable form having a channel extending in a sweep thereabout which channel substantially matches in cross sectional profile the cross sectional profile of said other semicylindrical element and then rotating such form to bend the element to conform to the curve of said sweEp along the longitudinal axis thereof with drawing of the element across a shoe which confines said element in said channel with such confinement introductory to the bending of the element, the cheek regions in said second wall section facing outwardly from the axis about which the wall section bends, and joining said sections together, with the edges bounding the cheek regions of the first section joined to the edges bounding the cheek regions on the second section.

Claim 2

A method of constructing a curved tube comprising the steps of forming a first wall section by deforming a first sheet to form an elongated substantially semicylindrical element having laterally spaced cheek regions extending longitudinally along its opposite sides, and draw bending said semicylindrical element by clamping an end region thereof against a rotatable form having a channel extending in a sweep thereabout which channel substantially matches in cross sectional profile the cross sectional profile of said semicylindrical element and then rotating such form to bend the element to conform to the curve of said sweep along the longitudinal axis thereof with drawing of the element across a shoe which confines said element in said channel with such confinement introductory to the bending of the element, the cheek regions in said first wall section facing inwardly toward the axis about which the wall section bends, forming a second wall section by deforming a second sheet to form another elongated substantially semicylindrical element having laterally spaced cheek regions extending longitudinally along its opposite sides and draw bending said other semicylindrical element by clamping an end region thereof against a rotatable form having a channel extending in a sweep thereabout which channel substantially matches in cross sectional profile the cross sectional profile of said other semicylindrical element and then rotating such form to bend the element to conform to the curve of said sweEp along the longitudinal axis thereof with drawing of the element across a shoe which confines said element in said channel with such confinement introductory to the bending of the element, the cheek regions in said second wall section facing outwardly from the axis about which the wall section bends, and joining said sections together, with the edges bounding the cheek regions of the first section joined to the edges bounding the cheek regions on the second section.

Claim 5

A method of manufacturing a curved tube comprising forming first and second elongate complementary wall sections, each having a transverse curvature corresponding to the circumferential curvature of the final tube and the two wall sections over their length bending in sweeps along their longitudinal axes, one of the wall sections having cheek regions facing toward the axis about which the wall section bends and the other wall section having cheek regions facing outwardly from the axis about which the wall section bends, each of the wall sections being produced by first forming an elongate sheet in the shape of a substantially semicylindrical element with laterally spaced cheek regions extending longitudinally along opposite side margins, and then draw bending the semicylindrical element, by clamping an end region thereof against a rotatable form having a channel extending in a sweep thereabout which channel substantially matches in cross sectional profile the cross sectional profile of the semicylindrical element and then rotating such form to bend the element to conform to the curvature of such sweep with drawing of the element across a shoe where confining of said element in said channel occurs introductory to the bending thereof, the two wall sections so produced being joined to each other through the edges which bound the cheek regions to the elements.

Claim 6

A method of manufacturing a curved tube comprising forming first and second elongate complementary wall sections, each having a transverse curvature corresponding to the circumferential curvature of the final tube and the two wall sections over their length bending in sweeps along their longitudinal axes, one of the wall sections having cheek regions facing toward the axis about which the wall section bends and the other wall section having cheek regions facing outwardly from the axis about which the wall section bends, each of the wall sections being produced by first forming an elongate sheet in the shape of a substantially semicylindrical element with laterally spaced cheek regions extending longitudinally along opposite side margins, and then draw bending the semicylindrical element, by clamping an end region thereof against a rotatable form having a channel extending in a sweep thereabout which channel substantially matches in cross sectional profile the cross sectional profile of the semicylindrical element and then rotating such form to bend the element to conform to the curvature of such sweep with drawing of the element across a shoe where confining of said element in said channel occurs introductory to the bending thereof, the two wall sections so produced being joined to each other through the edges which bound the cheek regions to the elements.