assistant to engineers in the coil coating industry for the summer. We coat

aluminium and then roll form it into various building products. Naturally,

we have a great deal of high capacity coilers/uncoilers.

I wish to calculate the torque required to accelerate the shaft to the

needed 400 feet per minute feed speed, given a coil outside diameter of 55

in., inside diameter of 20 in., and a coil mass of about 5000 lbs.

What i did was just took the coil alone by itself and calculated the torque

required to accelerate it to the needed speed within 2 seconds (reality),

but i got some ridiculously huge numbers. I used:

sum of torques = (polar moment of inertia)

***(angular acceleration)**

Taking polar moment to be: (0.5)*(mass)*(OD^2 + ID^2)

Taking polar moment to be: (0.5)*

and angular acceleration = tangential / radius.

The kicker is we have a 14.8 lb-ft 5 hp 1765 RPM motor, through a 20:1 gear

box, then a 2:1 reduction driving the shaft. Could anyone run the numbers

for me, or let me know if i'm missing something? Maybe i just have the

blinders on..

Thanks in advance for any help,

-JP Venturi, Second year McGill engineering,

formatting link