Question

Q3. ( 25 points) A rolling mill used to reduce a sheet strip by 3 mm in thickness. The sheet has 2.5 cm thickness and 30 cm in width. The rolling speed is 0.83 rev/sec. The sheet material flow stress is given by a = 275€0.15. A compression test was conducted to find the coefficient of friction and revealed that the coefficient of friction is 0.12. Check if the friction is adequate for the rolling operation. If it is calculate the roll force, torque, and horsepower.

Answer 1

Solution Given data > The sheet has thickness t=2.5cm = 25mm thickness to = 85-3- Jamm Roll Radios R=25cm - 250mm Rolling speed 7-0.83 revisec. Material flow stress or -> coefficient friction f-o-12 of » width W = 30cm =300mm 275 €° 15 Ih= teta -25-22 Dh:3mm Dhmax fxR 20.12x250 2 Domar = 3.6mm Sh <ohman So the friction is adequate for rolling operation To find - E= ln (+1/+2)

:lo 22 E=0.129 Length of contact: L: VRLOW -V250(3) 14:27.39mm Average flow stress Targe of its = 275 € 0:15 1.15 - 275x(0:12930 1 1:15 Darg = 175.88mpa Roll force (f) FF Sarg PargyA e gange wx L co - 175-88x300x21-39 -1445228.76N p= luus. 23 KM

Torque (7) = f*42 1445.23x27:39 Torque (1)- 1979 2.4m Horse power = P = 2nXFL. = 2xitxo.83% 145.23x10x27.39 P= 206.43x10 m/s P-206.43 kw (1Kw=13the P=276.83hp