METHOD FOR PRODUCING BIMETALLIC CENTRIFUGAL-CAST BILLETS AND BIMETALLIC WEAR RESISTANT TUBES FOR TRANSPORTING LOOSE ABRASIVE MATERIALS AND PULPS IN TUBE ROLLING AGGREGATES WITH PILGER MILLS

摘要

FIELD: rolled tube production, namely production of bimetallic centrifugal-cast billets and bimetallic wear resistant tubes, possibly used in tube rolling aggregates with pilger mills.;SUBSTANCE: method comprises steps of centrifugal casting of hollow bimetallic billets with wear resistant inner layer whose thickness consists 50-60% of wall thickness; heating billets till yielding temperature; rolling them in tube rolling aggregates with pilger mills to bimetallic tubes having wear resistant cladding layer consisting no more than 50% of whole thickness of wall at elongation degree no more than 9 that is at μ≤ 9.0. Casting of hollow centrifugal-cast billets and rolling of bimetallic tubes in pilger mills are realized while taking into account loss of plastic outer layer of centrifugal-cast bimetallic billets at heating them for rolling process in heating furnaces till yielding temperature. Thickness values of plastic layer of bimetallic centrifugal-cast billets are increased while taking into account loss caused by heating billets till yielding temperature at increasing their outer diameters according to given formula where D - diameter of centrifugal-cast billet, mm; Δ_s - loss value of thickness of plastic outer layer of centrifugal-cast billet at heating it till yielding temperature, mm; K - metal loss factor at heating centrifugal-cast billets till yielding temperature. Invention provides possibility for producing high-quality tubes with length 10 - 12 m having increased by 1.5 - 2.0 times wear-resistant layer and used for transporting abrasive loose materials at condition of permafrost. It allows not to use for such purpose tubes produced by joint-stock company "Diamonds Russia-Saha" and. It provides increased by 1.5 -2.0 times useful life period of such tubes in comparison with tubes rolled from bimetallic centrifugal-cast tubes according to known process.;EFFECT: improved operational parameters of tubes.;2 cl, 1 tbl