Hey guys and girls. I'm a second year mech eng student, working as an
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)
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
Thanks in advance for any help,
-JP Venturi, Second year McGill engineering,
- posted 16 years ago