Calculating Torque with Auger
Calculating Torque with Auger
(OP)
I am developing an application with an auger in which this auger will be pushing balls up a tube. I am assuming this is working much like a worm gear. The weight of the balls equals about .5 lbs but I would like to have 2.5lbs of pressure applied to them. The auger will be powered by a DC motor and I need to figure out the torque rating needed for this motor to push this kind of weight in inch pounds. The motor needs to spin at 1500-1800 RPM if that is helpful. Does anyone have a formula or formulas for calculating something like this? The auger spec drawing is located at www.develonet.com/auger1.GIF
Please detail your formula if you have one.
Thanks a ton!
Please detail your formula if you have one.
Thanks a ton!





RE: Calculating Torque with Auger
RE: Calculating Torque with Auger
T = n*Wb*f*p/(2*pi)
Where T = torque applied
p = screw pitch
n = number of balls present in 1 turn of screw (probably non-integer)
Wb = weight of a ball
f = desired weight multiplier factor (5 as specified)
This totally ignores any friction effects which might be present. Hopefully, your 5x multiplier will take care of that. Figuring out n is an exercise in geometry.
RE: Calculating Torque with Auger
T=F (d_m/2) [sin(a) + u cos (a)] / [[cos (a) - u sin (a)]
F= force/load being moved
d_m = mean diameter
u = coef of friction
a = lead angle of auger
RE: Calculating Torque with Auger
Since my equation is for a frictionless power screw, your equation should reduce to the same thing as mine for u = 0, and indeed it does.
Using your nomenclature, without friction your equation would be:
T = F*d_m/2*tan(a)
Since tan(a) = p/(pi*d_m), we obtain
T = F*p/(2*pi)
which is the same as my equation where F = n*Wb*f
Exactly how one should incorporate friction seems somewhat arguable, (possible extra friction on side walls, unknown entry and exit conditions etc), but since DEVELONET is using such a large safety factor, it would not seem terribly important, at least to me.
RE: Calculating Torque with Auger
I'll buy your argument, since we are talking about balls which are probably rolling, so negligible friction. (Especially with your fudge factor, f)
RE: Calculating Torque with Auger
RE: Calculating Torque with Auger
RE: Calculating Torque with Auger
There are two pieces of software that will help you with your problem.
One deals with worm drives where you can calculate torques for a given axial load
The other has to do with matching a DC motor with a gear box to achieve a desired speed of operation.
http://members.rogers.com/webgear/home.htm