Question

Explain analytically why the neutral point willshift toward the entry point in hot rolling for (a) increasedfriction coefficient values, and (b) increasedreduction in workpiece thicknesses.

Answer 1

The moment the plate touches the rolls, the rolls try to pull it and increase its velocity. The point at which the velocity of the plate becomes equal to the velocity of the roll (tangential velocity) is called neutral point and it's position from the initial point of contact depends upon how easy or difficult it is for the rolls to pull the plate.

As an increase in the coefficient of friction makes pulling easier so the neutral point shifts to the left.

Similarly by keeping the same parameters if the thickness of the incoming plate is increased, then pulling becomes difficult and external pressure has to be applied at the entry and thus the neutral plane shifts to the right.