Some Basics of Rolling and Rolling Mills...

Some Basics of Rolling and Rolling Mills Rolling is the process of plastically deforming metal by passing it between rolls. It is the most widely used forming process, which provides high production and close control of final product. During rolling metal is subjected to high compressive stresses as a result of the friction between the roll and the metal surface. Leonardo da Vinci invented the first rolling mills but only after a few centuries rolling mills became important for the steel industry. Modern rolling practice is attributed to Henry Cort who got a patent for use of grooved rolls for rolling iron bars. Henry Cort is also called “father of modern rolling”. The first rail mill was established in 1820 while the first plate mill was exhibited in 1851. Three high mills for rolling heavy sections were introduced in 1853. Hot strip mill were developed in America in the first half of the twentieth century. Basic concept of the rolling The arc of contact between the rolls and the metal is a part of a circle. The coefficient of friction is constant in theory, but in reality it varies along the arc of contact. The metal is considered to deform plastically during rolling. The volume of metal is constant before and after rolling. In practice the volume might decrease a little bit due to close up of pores. The velocity of the rolls is assumed to be constant. The metal only extends in the rolling direction and there is no extension in the width of the material. The cross sectional area normal to the rolling direction is not distorted. Factors influencing rolling The major factors which influences the rolling process are given below The diameters of the rolls The amount of reduction in a...