METHOD FOR PRODUCING CONE ELONGATED HOLLOW METALLIC ARTICLE BY HOT ROLLING Russian patent published in 2006 - IPC B21B21/00 

FIELD: metallurgical production processes, namely method for hot rolling of cone elongated hollow metallic articles from cylindrical tube blanks in tube rolling plants with pilger mills and automatic mills at lowering diameter of blank and increasing its wall thickness from one end to other.

SUBSTANCE: method comprises steps of heating blanks up to yielding temperature; piercing them in skew rolling mills; rolling in plants with pilger mills and automatic mills; cutting by measured length pieces; rolling in stretch reducing mills including stands with three or four rolls. After cone elongated hollow product is fed to roll pass of last stand of stretch reducing mill, rolls of all stands are braked for arresting them during time period t. Rolls of each stand except one during said time period are drawn apart by value δ. Time period till complete arresting of stretch reducing mill is determined according to formula: t = L₁ / v_blμ₁ = L _i/_{Vi μi where L1 -spacing between axes of first and second stands, mm; Vbl - blank speed, mm/s; μ 1 - elongation degree in first stand; L i - spacing values between axes of stands of stretch reducing mill, mm; V i - motion speed of blank of cone elongated hollow article in i-stand, mm/s; μ i - elongation degree in i-stand of stretch reducing mill determined according to formula: μi = {(Di-1 - S i-1)S i-1}/{(Di -Si)Si} where D i -diameter of cone elongated hollow article after i-stand, mm; Si - wall thickness of cone elongated hollow article after i-stand, mm; D i-1 -diameter of cone elongated hollow article after (i - 1)-stand, mm; Si-1 - wall thickness of cone elongated hollow article after (i-1)-stand, mm. Drawing apart value of rolls in each stand is determined with use of expression: δ i =D i-1 - Di. Spacing between axes of stands of stretch reducing mill are variables whose values are determined according to expression L i = L 1 μ2 μ3 μ i-1. Cone elongated hollow articles are discharged to inlet side of stands of stretch reducing mill due to reversing of stand rolls. Then articles are fed to skid for cooling and feeding for finishing operations including straightening, removal of technological scrap, inspection and reception of ready products.}

EFFECT: possibility for realizing (for the first time in world) flow type industrial production of high-quality cone elongated hollow metallic articles with desired geometry parameters_{in tube rolling plants with pilger mils and automatic mills, possibility for satisfying demands of national economy in such products suitable for export.}

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