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· Assume the reaction on the
rolls occurs at l/2 (as shown on the lower roll) then the roll torque T =
(Fl)/2 = (σy w l2)/2 = σy w r(t1 - t2)/2.
· The torque required to
drive the rolls increases as the yield stress of the material.
· The torque, and hence the rolling work,
increases with roll diameter. Small diameter rolls should, therefore, be used.
· In general, the yield
stress
decreases with temperature and hot rolling may be favored over cold rolling
from the point of view of energy requirements.
· Hot rolling also reduces the work hardening during
the forming of non-ideal plastic materials.
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