METHOD OF PRODUCING VARIABLE CROSS-SECTION THIN-WALL SHELLS Russian patent published in 2012 - IPC B21D22/14 

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to production of thin-wall high-strength shells from steel tube billets. Tubes made from killed steel represent said billets. Forming is performed by rotary and/or press processing to produce curvilinear, transition and cylindrical sections with axial direction of deformation. First, machined are transition conical and curvilinear parts with wall thickness and ultimate strength increasing and diameter decreasing toward reduced end. Then, transition part with variable cross-section and cylindrical part with tapering wall sections are processed in opposite direction. Note here that transition part is formed with cylindrical fillet with inclination of smaller than inclination of transition part generatrix in initial machining. At the end of machining, annealing is performed to reduce strain at 340-360°C.

EFFECT: higher surface precision and quality.

10 cl, 8 dwg, 1 tbl, 2 ex