How Much Torque is Required to Rotate a 1500lb Steel Drum?

In summary, the conversation discusses the need to rotate a 1500lb steel drum with an 8 foot diameter to wrap up air filter material. The drum is supported by bearings and needs to turn at 0.02rpm. The torque required is calculated using the moment of inertia equation for a hollow cylinder and is found to be 8.81lb-in. The group discusses if this value seems low and considers the bearing friction and efficiency, as well as the tension of the filter material, as potential factors affecting the required torque. They also review the correct formula for calculating moment of inertia and consider the slow rotational speed of 0.02rpm. Finally, they discuss the possibility of the wrapping mechanism adding additional load to the drum.
  • #1
SevenToFive
56
3
We have a 1500lb steel drum that has a 8 foot diameter that we need to rotate to wrap up air filter material. The drum is supported by bearings on both sides and needs to turn at 0.02rpm.
I calculated the torque, using T=Moment of Inertia * Angular Acceleration. For the moment of inertia I used the equation for a hollow cylinder.
Gravity =386.088in/sec^2
For the weight I figured 2500lbs to factor in losses through friction(0.5). Outside diameter with the roll of air filter material would be 109 inches, inside diameter =100 inches. Final rpm = 0.02, Acceleration time is 5 seconds.

The angular acceleration =0.02*2*3.14/60/5 = 0.00042Rad/sec^2
Moment of inertia = 21041.835lb-in-sec^2
T=I*AA = 21041.835lb-in-sec^2 * 0.00042rad/sec^2
T=8.81lb-in

However that value seems very low to me. Any help is greatly appreciated.
 
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  • #2
SevenToFive said:
T=8.81lb-in
... and, in "ft-lbs?" Can you turn it by hand? With a "cheater?"
 
  • #3
Bystander said:
... and, in "ft-lbs?"
Went the wrong way, sorry. The "by hand" inquiry stands.
 
  • #4
Calculate the torque required to turn the drum based strictly upon the bearing friction as a comparison for judging if your calculated starting torque is greater than the basic required rotating torque.
 
  • #5
JBA said:
Calculate the torque required to turn the drum based strictly upon the bearing friction as a comparison for judging if your calculated starting torque is greater than the basic required rotating torque.
I would have 1500lbs, 0.50 for bearing efficiency, and 48" from the center of the drum to the outside, which would give me 36000lb-in, which seems a bit on the high side.
 
  • #6
I am not sure to what the term "bearing efficiency" refers, since the rolling resistance of an anti-friction bearing is generally based upon the "bearing friction factor" and 0.50 is an extremely high "bearing friction factor" for any type of anti-friction (rolling type) bearing.

See the below website for a typical anti-friction (rolling bearing) resistance torque calculation.

http://www.skf.com/us/products/bear...ction/estimating-frictional-moment/index.html

Also, I believe you used the wrong Moment of Inertia equation for your calculation; and, should have used the "Polar Moment of Inertia" equation for a cylinder rotating about its axis.
 
  • #7
.02 RPM is VERY VERY slow (once an hour?).. I think in this case the amount of energy needed to accelerate it can pretty much be ignored, you're BIG one is friction which will be orders of magnitude higher.

Looking at this http://www.skf.com/ca/en/products/b...ction/estimating-frictional-moment/index.html and getting some guidelines, the formula is
M = 0,5 μ P d
It seems to me you've mistaken 0.5 as the friction coefficient μ, it is NOT.

From their table, I'm going to choose "Self aligning ball bearings" since most pillow block bearings in industrial applications would fall into that category.. μ for them is 0.0010. You haven't mentioned the shaft size, for that kind of load I'm going to take a stab at guessing a 3" bearing (the d component in the formula)
So that brings me to the following
M = 0.5 * .0010 * (1500 lb * .454kg/lb) * (3in * 25.4 mm/in)
M = 0.5 * .0010 * 681 * 76.2
M = 25.9N*mm (This is far less than I had estimated in my mind)

However, is the wrapping mechanism going to put any load on the drum? that may be the largest force working against you.
 
  • #8
Rx7man said:
However, is the wrapping mechanism going to put any load on the drum? that may be the largest force working against you.

+1.

What is the tension in the filter material?
 

1. What is torque and how does it relate to rotating a drum?

Torque is a measure of the turning force on an object. In the case of rotating a drum, torque is the force applied to the drum in order to make it spin.

2. How is the torque needed to rotate a drum calculated?

The torque needed to rotate a drum depends on several factors such as the mass of the drum, the inertia of the drum, and the speed at which it needs to rotate. It can be calculated using the formula: torque = mass x acceleration x radius.

3. What factors can affect the torque required to rotate a drum?

The torque required to rotate a drum can be affected by the size and weight of the drum, the friction between the drum and its bearings, and the speed at which it needs to rotate. Additionally, the shape and distribution of the load inside the drum can also affect the torque needed.

4. How can torque be applied to rotate a drum?

Torque can be applied to rotate a drum through various methods such as using a motor, a gear system, or manual force. The amount of torque needed will depend on the method used and the factors mentioned in the previous questions.

5. How can torque be controlled to rotate a drum at a specific speed?

To control the speed at which a drum rotates, the torque can be adjusted accordingly. This can be done by changing the motor speed, adjusting the gear ratio, or applying more or less force manually. Additionally, using sensors and controllers can also help regulate the torque and maintain a specific speed for the drum rotation.

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