METHOD FOR MAKING SEAMLESS HOT ROLLED TUBES IN TUBE ROLLING AGGREGATES WITH PILGER MILLS Russian patent published in 2005 - IPC

FIELD: rolled tube production.

SUBSTANCE: method comprises steps of heating ingot-billets; piercing them in helical rolling mill to sleeves with different lengthwise elongation factors μ_pr and μ_pr1; rolling in pilger mill with elongation factor μ_{pil .} Ingot-billets are pierced to sleeves at different lengthwise elongation factors μ_pr, μ_pr1, μ_pr2 where maximum elongation value μ_pr2 corresponds to front end of sleeve forming guided end of tube in pilger mill. Elongation factor of front end of sleeve is decreased from μ_pr2 to μ_pr due to drawing roll apart along length (0.15 -0.20)L_T forming guided end of tube in pilger mill and determined according to expression μ_pr2 = (1.4 -1.6)μ_pr where μ_pr -elongation factor in piercing mill at stable rolling process of central portion of sleeve equal to (0.65 -0.75)L_T. Elongation factor of back end of sleeve is increased from μ_pr to μ_pr1 due to drawing rolls together along length of sleeve equal to (0.1 - 0.15)L_T forming pilger head determined according to expression μ_pr1 = (1.3 -1.5)μ_pr.

EFFECT: lowered metal consumption, enhanced efficiency of pilger mills, prevention of crumbling back ends of sleeves.

3 cl, 1 dwg, 1 tbl