GB687283A - Improvements in or relating to a method of and apparatus for the manufacture of seamless metal tubes - Google Patents

Abstract

687,283. Making seamless tubes; rolling. STEWARTS & LLOYDS, Ltd. Jan. 23, 1951 [Jan. 23, 1950], No. 1765/50. Classes 83 (ii) and 83 (iv). A method of making a seamless metal tube comprises forming a hollow and delivering it to the inlet side of a skew rolling mill, advancing a mandrel bar into the hollow through the rear end, positioning the mandrel at the rolls and skew rolling the hollow over the mandrel while the mandrel bar is in tension. The hollow may be in the form of a " bottle " or open at both ends, and formed, for example, by piercing a hollow billet which is treated in a plug mill, a push bench or a continuous seamless tube mill. Alternatively the hollow may be produced in a rotary piercing mill or in a plant comprising a system of piercing followed by a pilger mill. Billets are delivered to a piercing mill 6 from a furnace 1, pierced and delivered to a roller table 9 where apparatus 13 inserts a mandrel 30 on a bar 14 into the hollow 7, pusher rolls 15 then feeding the assembly between skew rolls 16 which feed the elongated work away from the mandrel. From the rolls 16 the tubes may pass to polishing rolls 21 and thence to sizing rolls 25, after reheating by a furnace 24. The mandrel bar 14 which, with the mandrel 30 may be hollow to allow the circulation of cooling fluid, is mounted in a thrust-block 32 carried by the piston of an air cylinder 51, by which it may be moved towards a guide block 50 until the faces 52, 53 are in contact, thus positioning the plug axially in the billet. The thrust block may be returned to the position shown, Fig. 5, under the action of a weight 54. The mandrel may be replaced by others of different size. Guide shoes 33, Fig. 4, prevent ovalling of the tube and guide the work.