| 摘要 |
FIELD: rolled tube production, namely methods for making and using technological tools, possibly at making mandrels of pilger mills for rolling hot rolled tubes with large and mean diameters. ^ SUBSTANCE: method for making mandrels of pilger mills for rolling hot rolled tube with diameters 273-550 mm comprises steps of casting steel ingots; forging cylindrical or hollow blanks; rough working and heat treatment of them; mechanically working mandrels for final size and strengthening them due to rolling out by means of roller; exploiting mandrel until formation of lattice of thermal-erosion cracking. Mandrel blanks are made of carbon steel. On outer surface of blanks heat- and wear-resistant layer is surfaced. After occurrence of thermal-erosion cracking mandrels are reground; heat- and wear- resistant layer is surfaced. Blanks are worked for final size and strengthened due to rolling out by rollers. Thickness of surfaced heat- and wear-resistant layer is determined according to expression Delta = A (1 + K* D/S), where A - minimum thickness of surfaced layer after finishing equal to 10 mm; D - maximum diameter of tube rolled on mandrel, mm; S - minimum thickness of wall of tubes rolled on mandrel, mm; K - coefficient taking into account geometry size of tubes. Heat- and wear-resistant layer is multiply surfaced on mandrel blanks. Invention provides possibility for using mandrel blanks of carbon steel instead of alloy steel. ^ EFFECT: lowered consumption of mandrels, reduced cost of conversion of hot rolled tubes in tube rolling aggregates with pilger mills. ^ 3 cl, 1 tbl |
