Bearings for Rolling mill Rolls...

Bearings for Rolling mill Rolls Rolling mills for rolling of steel differ in many aspects with each other. The rolling mills are of different sizes and capacities. The mills roll steel materials of different cross-sections, sizes and qualities and in material conditions which are either hot or cold. The mills have different configurations and speeds of rolling. The configurations of the mills can vary from cross country, reversing, semi continuous to continuous. The equipments of rolling mills can have manual operations, mechanical operations, electro-mechanical operations, pneumatic operations, hydraulic operations, or a combination of all of these. The controls provided in the mills can be manual controls, remote controls, instrumented controls, or fully automated controls. Further in many types of mills even heat treatment processes are integrated. In spite of the so many differences, all the rolling mills have in common some basic technologies and equipments. All the rolling mills have rolls for the rolling of materials which are fitted in roll stands. Rolls are either driven by electric power or friction driven and are to resist many forces for normal rolling. The roll stands can have two rolls, three rolls, four rolls, six rolls, or a set of multiple rolls mounted on them depending on the types of mills. During rolling, the load on the rolls gets transferred to the roll neck bearings and their assembly (chocks). Rolls for their smooth rotation as well as for resistance to different forces need ‘bearings’.  Roll bearings are to meet the basic need of the rolling mill which is the smooth rolling of the steel products. They are friction reducing devices which provide support to the rolls for effective rolling with minimum of energy loss. The bearings are designed to withstand high rolling loads, heavy shocks, varying...

Rolling Process for Steel Mar27

Rolling Process for Steel...

Rolling Process for Steel Rolling is the process of plastically deforming steel by passing it between rolls. Rolling is defined as the reduction of the cross sectional area of the steel piece being rolled, or the general shaping of the steel products, through the use of the rotating rolls. Rolling of steel is one of the most important manufacturing processes for steel. It is usually the first step in the processing of steel after it is made and cast either in Ingot or continuous cast product in a steel melting shop. The initial rolling of steel is done in a hot rolling mill where blooms and slabs are rolled down to various rolled products such as plate, sheet, strip, coil, billet, structures, rails, bars and rods. Cold rolling of steel is also carried out for some products. Many of these rolled products such as rails and reinforcement bars etc. are directly used by the consumers while the other rolled products are the starting raw materials for subsequent manufacturing operations such as forging, sheet metal working, wire drawing, extrusion, machining, and fabrication industry. Steel rolling can produce a wide range of products. The width of a rolled product can vary from a few millimeters to several meters while the thickness can vary from 0.1 mm to more than 200 mm. The rolled section can be square, rectangular, round or shaped sections. Different rolling processes for steel are shown in Fig 1 Fig 1 Rolling processes of steels Principle of rolling steel During rolling, steel work piece is subjected to high compressive stresses as a result of the friction between the rolls and the surface of work piece being rolled. The work piece is plastically deformed by the compressive forces between two constantly rotating rolls. These...

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...