- Hi friend hear i write a topic on Study Note on Rolling with video. Rolling is the most extensively used metal forming process and its share is roughly 90%.
1.The material to be rolled is drawn by means of friction into the two revolving roll gap
2.The compressive forces applied by the rolls reduce the thickness of the material or changes its cross sectional area
3.The geometry of the product depend on the contour of the roll gap
4.Roll materials are cast iron, cast steel and forged steel because of high strength and wear resistance requirements
5.Hot rolls are generally rough so that they can bite the work, and cold rolls are ground and polished for good finish
6.In rolling the crystals get elongated in the rolling direction. In cold rolling crystal more or less retain the elongated shape but in hot rolling they start reforming after coming out from the deformation zone
7.The peripheral velocity of rolls at entry exceeds that of the strip, which is dragged in if the interface friction is high enough.
8.In the deformation zone the thickness of the strip gets reduced and it elongates. This increases the linear speed of the at the exit.
9.Thus there exist a neutral point where roll speed and strip speeds are equal. At this point the direction of the friction reverses.
10.When the angle of contact α exceeds the friction angle λ the rolls cannot draw fresh strip
11.Roll torque, power etc. increase with increase in roll work contact length or roll radius
See The Video of Rolling