09-10-2010, 01:43 PM
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Rolling mill
Presented
By
Viraj
Introduction to Rolling
Rolling is a bulk deformation process in which the thickness of the work is reduced by compressive forces exerted by two opposing rolls. The rolls rotate to pull and simultaneously squeeze the work between them.
“Flat Rolling”, used to reduce the thickness of a rectangular cross section. A closely related process is “shape rolling”, in which a square cross section is formed into a shape such as an I-beam.
Introduction to Rolling
After casting, ingots are rolled into one of three intermediate shapes called blooms, billets, and slabs:
Blooms have square cross section 6” x 6” or larger. They are rolled into structural shapes.
Billets have square cross section 1.5” x 1.5” or larger. they are rolled into bars and rods.
Slabs have rectangular cross section 10” x 1.5” or larger. They are rolled into plates, sheets and strips.
As any other metal forming process, rolling can be performed hot (hot rolling) or cold (cold rolling).
Most rolling is carried out by hot rolling, owing to the large amount of deformation required.
Hot-rolled metal is generally free of residual stresses, and has isotropic properties. On the other hand, it does not have close dimensional tolerances, and the surface has a characteristic oxide scale. Moreover, cold rolled metals are stronger.
