METHOD FOR MAKING MANDRELS OF PILGER ROLLING MILLS

摘要

FIELD: rolled tube production, namely processes for making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters. ^ SUBSTANCE: method of making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters in range 273-550 mm comprises steps of casting steel ingots; forging cylindrical solid or hollow blanks; subjecting blanks to rough working, to heat treatment and working them for final size; hardening blank surface by means of roller; maintaining mandrels until formation of lattice of thermal erosion cracking. Before heat treatment constant- thickness heat- and wear-resistant layer is welded on outer surface of carbonaceous mandrel blank along 2/3 of its working length of mandrel from its joint part while taking into account allowance for mechanical working. Thickness of said layer is decreased towards end of mandrel by 3-4 times. During process of operation mandrel is reground. Then heat- and wear-resistant constant-thickness layer is welded on outer surface of mandrel along 2/3 of its working length from joint part. Thickness of said layer is decreased towards end of mandrel by 3-4 times. Regrinding and layer surfacing steps are performed multiply. Invention allows to use carbon steel instead of alloyed steel at making mandrels, provides increased by 3.5 - 4 times strength of mandrels. ^ EFFECT: lowered cost of mandrels and therefore reduced cost of conversion of hot rolled tubes in tube rolling aggregates with pilger mills. ^ 1 tbl