22-06-2012, 05:34 PM
ROLLING
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Introduction
Rolling is a metal forming process in which metal stock is passed through a pair of rolls.
Due to compressive stress exerted by rolls, the metal thickness reduces.
History of modern rolling
Modern rolling practice can be attributed to the pioneering efforts of Henry Cort (England).
Used grooved rolls for rolling iron bars.
Patent issued- 1783
Modern writers have called him “father of modern rolling."
Hot rolling
Occurs above the recrystallization temperature of the material.
Poor surface finish due to oxidised metal
Complex part shapes can be generated
Cold rolling
metal usually at room temperature
increases strength via
strain hardening
(strengthening of a metal by plastic deformation)
improves surface finish and holds tighter tolerances
Processes
Roll bending produces a cylindrical shaped product from plate or steel metal.
Flat rolling is the most basic form of rolling with the starting and ending material having a rectangular cross-section.
Ring rolling is a specialized type of hot rolling that increases the diameter of a ring.