Rolling of Steel in small and medium sized Rolling Mills Jun09

Rolling of Steel in small and medium sized Rolling Mills...

Rolling of Steel in small and medium sized Rolling Mills Rolling of steel consists of passing the material, usually termed as rolling stock, between two rolls driven at the same peripheral speed in opposite directions (i.e. one clockwise and the second anti-clockwise) and so spaced that the distance between them is somewhat less than the thickness of the steel section entering them. In these conditions, the rolls grip the material and deliver it reduced in thickness, increased in length and probably somewhat increased in width. This is one of the most widely used processes among all the metal forming processes, because of its higher productivity, close control of the rolled product, and lower operating cost. Rolling is able to produce a product which is having constant cross section throughout its length. Many shapes and sections are possible to roll by the steel rolling process. Rolling of steel is a metal forming process used for plastic deformation of the steel. Plastic deformation is caused by the compressive forces applied through the rotating rolls. High compressive stresses are as a result of the friction between the rolls and the surface of the steel material. The steel material gets squeezed between the pair of rolls mounted in a roll stand, as a result of which the thickness of the steel being rolled gets reduced and the length is increased. Steel sections are generally rolled in several passes, whose number is determined by the ratio of initial input material and final cross section of finished product. The cross section area is reduced in each pass and form and the size of the rolling stock gradually approach to the desired profile. Mostly, rolling is done at high temperature, which is called hot rolling, because of requirement of large deformations....

Slit rolling for bar production May30

Slit rolling for bar production...

Slit rolling for bar production In merchant bar mills with conventional rolling, rounds and rebars (both of them commonly known as bars) are produced from billets which are rolled in a sequence of passes through a multi stand rolling mill. Each of the stands is having a set of two rolls, grooved on the circumference to give together a desired pass shape. Cross section of the billet is gradually reduced and shaped in a sequence of passes till the final shape and cross sectional size is obtained. While rolling bars in a merchant bar mill, the productivity of smaller diameter bars is generally lower than the bigger diameter bars. To improve such productivity, one of the most significant developments in the area of bars production in recent years is the slit rolling. This method of rolling bars is also called “Multi Slit Rolling (MSR)”. The process of slit rolling is to roll two or more bars simultaneously from a single billet. When compared with the conventional single strand continuous rolling, MSR has reduced number of passes. The multi slit rolling technology use a combination of special roll pass design and designated guide equipment to prepare, shape and longitudinally separate the incoming billet into two or more individual strands for further rolling into the finished size. The bar is slit by rolls without any other special slitting devices. The numbers of slits can be selected by the appropriate design of the roll grooves. A bar can be separately split into two, three or four pieces in one pass. By selecting the number of slits according to the product size, the same productivity of all the products can be achieved in the bar mill. The slitting is done by applying axial force which is done by using special pass...