UA82972C2 - Method of plugless continuous longitudinal rolling of pipes in multistand mill - Google Patents

Abstract

The invention relates to the methods of metal forming and can be used for continuous plugless rolling of seamless and welded pipes. A method includes deformation of billet in several consecutive roll openings. Moreover, first the module of elasticity () and yield point () of the material of billet are defined at deformation in the last roll opening, which diameter (is defined by mathematical dependence as function of the diameter of pipe in cold state (), coefficient of linear temperature expansion of the material of pipe (), temperature of rolling in last roll opening (), module of elasticity () and yield point () of the material of billet at deformation in the last roll opening, in accordance with the relationship:,where- diameter of last roll opening in the direction of rolling, mm;- diameter of pipe in the cold state, mm;- coefficient of linear temperature expansion of the material of pipe, 1/°C;- temperature of the material of pipe in the last roll opening in the direction of rolling, °C;- yield point of the material of pipe at deformation in the last roll opening in the direction of rolling, MPa;- modulus of elasticity of the material of billet at deformation in the last roll opening in the direction of rolling, MPa. The invention provides for decrease of the divergence between real and assigned nominal diameter of finished pipes by 15 %.