METHOD FOR PREPARING BLANKS (SLEEVES) OF ALLOYED STEELS AND ALLOYS FOR PILGER ROLLING OF TUBES Russian patent published in 2003 - IPC

FIELD: rolled tube production processes, namely manufacture of seamless hot rolled tubes in tube rolling lines with pilger mills. SUBSTANCE: method for preparing sleeve blanks comprises steps of using carbonaceous branch pipes (backing rings) having cylindrical and cone portions whose dimensions are determined according to expressions: Lt = 0.6 - 0.8 Dsl; Lcyl = 0.35 - 0.4 Dsl; Lcon = 0.25 - 0.4 Dsl; Dcyl = 1.15 - 1.3 Dsl; Dcon = 1.0 - 1.1 Dsl, where Dsl - sleeve diameter, mm; Lt - total length of carbonaceous bran h pipe,mm; Lcyl - length of cylindrical portion of branch pipe, mm; Lcon - length of cone portion of branch pipe, mm; Dcyl - diameter of cylindrical portion of branch pipe, mm; Dcon - minimum diameter of cone portion of branch pipe, mm. Invention provides multiple use of carbonaceous branch pipes (backing rings), elimination of jamming mandrels at rolling tubes of high-alloy steels and alloys with increased casting expansion factor, total rolling around of pilger heads. In order to provide multiple use of branch pipes and to eliminate jamming of mandrels in tubes, diameter of cylindrical portion is increased until 1.3 Dsl at length 0.35 - 0.40 Dsl. In order to enhance starting-up, small base of cone portion of branch pipe adjoins to sleeve end whose outer diameter is equal 1.0 - 1.1 Dsl. When diameter of cylindrical portion increases outer diameter of sleeve end increases from 0.25 until 0.40 Dsl. EFFECT: multiple use of carbonaceous branch pipes, elimination of mandrel jamming in tubes at rolling. 3 cl, 1 dwg