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...

Bearing Basics and Types of Bearings...

Bearing Basics and Types of Bearings  The term bearing is derived from the verb ‘to bear’, a bearing being a machine element that allows one part to bear (i.e., to support) another. Bearings are highly engineered, precision made components that enable machinery to move at extremely high speeds and carry remarkable loads with ease and efficiency. Generally speaking, bearings are devices that are used to enable rotational or linear movement, while reducing friction and handling stress. Bearings are considered to be the most critical components of machinery. Bearings are machine elements that constrain relative motion and reduce friction between moving parts to only the desired motion. The design of the bearings may provide for free linear movement of the moving part or for free rotational around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Many bearings also facilitate the desired motion as much as possible, such as by minimizing friction. Bearings can have many forms, but supports only two types of motions namely linear motion or rotary motion. There are two types of bearings, contact and noncontact. Contact bearings – They have mechanical contact between elements, and they include sliding, rolling, and flexural bearings. Mechanical contact means that stiffness normal to the direction of motion can be very high, but wear or fatigue can limit their life. Fig 1 shows different types of sliding and rolling bearings. Non contact bearings – They include fluid bearings and magnetic bearings. The lack of mechanical contact means that static friction can be eliminated, although viscous drag occurs when fluids are present; however, life can be virtually infinite if the external power units required to operate them do not fail. Fig 1 Different types of sliding and rolling bearings  Contact bearings Contact bearings are...