Rolling

Abstract

Terminology of rolled product, different methods of rolling and quantities characterizing deformation. Classification of rolling mills. Different types of rolling mills, such as cluster mill, Sendzimir cold-rolling mill and planetary hot-rolling mill, pendulum mill, contact-bend-stretch mill, universal mill. Hot and cold-rolling practice. Deformation zone in rolling, angle of bite and artificial methods to increase it, neutral point (no-slip point) and no-slip angle. Ekelund expression for no-slip angle. Forward slip, its relation with no-slip angle, its measurement and importance. Elastic deformation of rolls: roll flattening and roll deflection. Simplified assessment of rolling load and Ekelund equations for loads in cold and hot rolling. Theory of rolling: derivation of differential equation of friction hill. Bland and Ford theory of cold rolling: roll pressure with no external tensions and with back and front tensions, no-slip angle, rolling load and torque, maximum allowable back tension, estimation of friction coefficient. Sims’ theory of hot rolling: roll pressure, no-slip angle, rolling load and torque, limitations of theory. Mean strain rate in flat rolling with sticking friction. Lever arm ratio and its estimation from Sims’ theory, torque and mill power. Minimum thickness of rolled product. Factors controlling rolling process. Gauge control by considering mill modulus line and plastic deformation curve for work-metal and factors affecting outgoing gauge of rolled product. Defects in rolled products. Fundamentals of roll-pass design: types and shapes of passes, gap and taper of sides in pass, pass arrangement, pass sequences used in rolling of billets to rods and square bars. Production of seamless pipe and tube by hot rolling using rotary piercing mill, plug mill, continuous mill, pilger mill and finishing mills, such as reeling, sizing, stretch-reducing and expanding mills. Problems and solutions.