METHOD FOR MAKING CONE ELONGATED HOLLOW METALLIC PRODUCTS BY HOT ROLLING AND APPARATUS FOR PERFORMING THE SAME Russian patent published in 2006 - IPC B21B21/00 

FIELD: metallurgical production, namely of cone elongated hollow metallic products by hot rolling of cylindrical tubular blanks in new pilger mills at reducing diameter and thickness of blank wall from one end to other.

SUBSTANCE: method comprises steps of heating tube-blanks till plasticity temperature and rolling them in pilger mills on long cone mandrel between rolls whose gage passes along helical line relative to roll axes; placing axes of rolls in parallel on vertical plane; forming grooved pass of upper roll with right-hand helical line and grooved pass of lower roll with left-hand helical line or vice versa; determining number of turns of round variable gage according to expression: n = L sin α/ /(2πRr), where L - length of hollow cone product, mm; Rr - rolling radius of roll, mm; α - inclination angle of roll grooved pass axis to roll axis, °. Feeding mechanism performs reciprocation motion in accordance with roll rotation in horizontal plane by value determined according to formula N = n[(D max + D min)/2]+ K(n-1), where n - number of turns of roll grooved pass along roll, p.; D max - maximum diameter of grooved pass, mm; D min - minimum diameter of grooved pass, mm; K - width of roll beads between grooved passes, mm. Rolling is realized between rolls with sliding bearing assemblies. Rolls are moved in horizontal plane by means of rolling efforts or they are subjected to forced horizontal motion from separate drive operating in accordance with rotation of rolls. Rolls are returned to initial position at rolling process due to reverse rotation of rolls by means of main drive or they are subjected to forced horizontal motion from separate drive. Connection couplings and driving journals of working rolls of apparatus are in the form of telescopic systems providing movement of rolls in horizontal plane by value determined with use of formula N = n[(D max + Dmin)/2] + K(n-1).Feeding mechanism is inclined by angle α to horizontal axis of rolls. Diameters of cone mandrel are equal to inner diameters of base and top of elongated cone product. Conicity degree of mandrel exceeds that of elongated cone product by total elongation degree Σμ at rolling cylindrical tube for forming elongated cone hollow product; length of mandrel is less than that of product by Σμ times. Said values are determined according to formulae α₀ = α_pr x Σμ; L₀ = L/Σμ, where α₀ - conicity angle of mandrel, °; α_pr - conicity angle of product, °; Σμ - total elongation coefficient at rolling cylindrical tube to cone hollow product; L -length of cone product, mm.

EFFECT: possibility to realize industrial flow type production of high-quality cone elongated hollow metallic articles with desired geometry size at satisfying demands of national economy due to making competitive products.

9 cl