How to determine the power rating of both a pinion and a girth gear set

[pat123__]

Hi,

I'm a mechanical engineering intern who has been assigned a job that requires me to determine the power rating of pinion + girth gearset for a ball mill, because a more powerful motor is going to be added (so the mill can have a higher throughput).

I've been reading up on the two fundamental AGMA equations in the links below:

(For reference, these screenshots are taken from the document I found in

https://eis.hu.edu.jo/ACUploads/10526/CH 14.pdf)

My thought process is I would solve for the tangential load in both cases, with the bending and the contact stress set as the yield strength of the material the gears are made from. After I've solved for the tangential load, I would be able to work out the torque on the gears, hence I would be able to figure out the maximum power the gears can withstand before failing (since I know their rotational speeds).

Is this a correct thought process?

Any feedback would be much appreciated.

 

[mfgenggear]

There are a few you tube videos based on the agma calcs.that very good that are very in depth. And take a while.

 

[TWilkinson]

I'd recommend creating a parameterized spreadsheet so you can tweak your initial design. I'd also recommend using your material's fatigue strength instead of yield for peak continuous load; work with your engineering team to determine an ideal FoS. Fatigue strength can be estimated with UTS or measured surface hardness. I believe AGMA also has published values for most common gear materials. I would avoid yield strength unless you are interested in peak intermittent loading.

 

[desertfox]

Hi pat123

Won’t the torque requirement be the same as the current set up? In which case if you know that you can work out the power rating.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Compositepro]

A ball mill works by tumbling balls in a drum. There is an optimum speed and product loading to get the best tumbling action. If it is already optimized, a larger motor will do nothing. A variable speed drive may be more useful for finding the optimum speed, which will be the speed at which horsepower drawn by the mill is at maximum. Above a certain speed, the balls will just orbit with the drum. If this overloads the existing motor, then a larger motor would help.
The torque required by the mill is determined by the mill, not the motor.