Calculation of Centrifical Force of Vibrator

BobOstlund
(not verified)
Posted in: , on 19. Oct. 2005 - 19:33

I would like to know if I am calculating the pounds of centrifical force of a vibrator correctly.

I have the formula: Pounds of Centrifical Force

= 0.0000284 (inch-pounds) (RPM) (RPM)

As an example, I have a 2 inch diameter shaft turning at 1000 revolutions per minute. If I weld on a parallel 5 pound piece of 3 inch shafting (which is hard to do at 1000 rpm), the inch-pounds would be (1+1.5 inches)(5 pounds) = 12.5.

The Pounds of Centrifical Force =

= 0.0000284 (12.5) (1000) (1000) = 355

Is this the correct application, and formula??

Thanks, Bob Ostlund

Re: Calculation Of Centrifical Force Of Vibrator

Erstellt am 20. Oct. 2005 - 10:22

Gooday Bob,

Yes it all looks good to me.

Your static moment would be 12.5 lb.in, and your dynamic moment 25 lb.in.

If you were to fit your high tech mechanism into a screen with an all up weight of 100 lb, then you could expect a 0.25" dia vibrating stroke. (ie: dynamic moment divided by screen mass).

Your formula for centrifugal force in imperial units is correct.

You take care welding onto that shaft now!

John McKenzie
BobOstlund
(not verified)

Re: Calculation Of Centrifical Force Of Vibrator

Erstellt am 20. Oct. 2005 - 05:09

John, thanks for your review of my calculations. Especially, thanks for your additional notes on calculation of screen throw! Opps, I discovered that I have been using the static moment instead of the dynamic moment in figuring this- but not to worry, I don't work in a nuclear plant.

I better try an example to make sure I have this-

If I design a vibrating grizzly with a 0.5 inch diameter circle of throw, and a total weight of the grizzly screen plus gravel directly on the grizzly deck of 10,000 pounds, the required dynamic moment of the actuator would be:

(0.5 inch throw)(10,000 pounds) = 5000 inch pounds

The static moment would then be 5000 divided by 2 = 2500 inch pounds.

This moment could be developed by a 250 pound hunk of pig iron, the center of mass of which is 10 inches from the center of the turning shaft.

How does this look??

Thanks again, Bob Ostlund

Re: Calculation Of Centrifical Force Of Vibrator

Erstellt am 21. Oct. 2005 - 09:38

It still all looks good Bob. Your solution for the example that you give is correct.

Another way to look at it is:

m x R = M x r

where

m = mass of the eccentric counterweight

R = radius from centre of rotating shaft to the centre of gravity of the counterweights.

M = mass of total screen

r = radius of screen vibrating throw

John McKenzie

Calculation Counterbalance For Vibrating Screen

Erstellt am 29. May. 2012 - 10:57

dear all.

I am engineer for limestone process, I want to ask what is the simple steps to design and calculation for vibrating screen, eccentric type and conterbalance type

thanks before

Re: Calculation Of Centrifical Force Of Vibrator

Erstellt am 15. Jul. 2012 - 01:29
Quote Originally Posted by belly bertoView Post
dear all.

I am engineer for limestone process, I want to ask what is the simple steps to design and calculation for vibrating screen, eccentric type and conterbalance type

thanks before

Belly

I can't understand your request - could you please rephrase your question?

Regards

Ziggy Gregory

Ziggy Gregory www.vibfem.com.au