Involute spline alignment 3

[KllrWolf]

One of our customers has asked us at what angle of misalignment will problems start to occur. I am at a loss as to how to solve this, as all specs I have show no space. The customer is the one who has chosen the spline and coupling, and they are making the coupling themselves. I do know the coupling spline is DIN 5480 N100x2x48 and we are having our shaft sent out to get the matching spline. I do not know the tolerance, but was told it is standard tolerance. I also do not have the spec. The best(worst) part is that the customer wants to see all calculations and not just an answer (not allowed to tell them to bug off either). Any help to get me going in the right direction would be appreciated.

 

[gearcutter]

Any misalignment between the mating members of a spline coupling is going to cause some kind of wear.
The problem is in calculating what the actual amount of misalignment under load is.
If a fully aligned coupling cannot be guaranteed and keeping the wear to a minimum is the priority; then I would suggest you barrel or crown the profile of the male member and force feed the coupling with a recirculating lubricant.
There is no such thing as a “standard tolerance” in any of the spline standards I know of.
You must decide how much backlash and profile accuracy is required to do the job effectively and then chose the tolerances required.
To cover yourself; you need to get your customer to quote the tolerances that they require.
Generally tolerances are chosen based on the type of fit at assembly.

Zak Gear has posted an online calculator using equations derived from an article by Darle W. Dudley "When Splines Need Stress Control".
It uses fatigue and misalignment factors which are only based on constants so use with caution.
Here is the link:

http://www.zakgear.com/External_Spline_IN.html

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[KllrWolf]

Thanks for the link. It has been a help. While I am trying to figure out the math, I am still pushing to just tell the customer he is not allowed to cause the misalignment in the first place.

 

[linares]

KllrWolf,

You can have misalignment by having crowned teeth and the allowed misalignment will depend on the teeth design itself. Now the ANSI/AGMA 6123-B06 mentions that if you don't have crowned teeth in your spline you will have issues if your misalignment goes beyond 0.001 rad.

Here is also a paper that might help run through the calcs on the effect of misalignment if your client wants you to go that far.

http://www.hindawi.com/journals/ijrm/2008/321308/

I hope that helps,

cheers

 

[dinjin]

To answer your customers request, are they asking this for stiffness considerations, engaging considerations, is it one direction application, the length of the splines, the dp, the type of fit, etc.

 

[mfgenggear]

In addition what was said I just wanted to add to reinforce
the statement a spline must be designed with or with out misalignment.

In other words if there is going to be misalinement then the spline needs to be designed with a crown to allow for it.

My experience has been, that if the assembly is rigit. then there should not be any misallignment, there fore crowning not required.

The question needs to be asked if there is misalignment how much?
then the answer can be given.

But I wanted to add in the US spline spec. version ANSI B92.1
there are 2 types of splines. side fit splines(flat & fillet root) & a major dia fit splines, depending on what is required for the assembly.
In order for splines to assemble there must be clearance or back lash between the splines, A go gage & a no go gage are to use to verify that #1) it will assemble, #2) the spline are not out of spec. In addition there diffrent class of fits. depending on the
back lash required. close fit vs semi close fit, ect.

My 2 cents
Mfgenggear