Snap ring force

[carter213]

How can I calculate the radial squeezing force of a snap ring or retaining ring? I've done some searching, but I can only find info on dimensions and thrust loads.

Since it's a spring, I'm assuming there's a formula to calculate the force.

 

[israelkk]

Associated Spring - Barnes (SPEC) Design Handbook -Engineering Guide To Spring Design 1987 edition page 66 gives the required formulas for constant cross section area (of the wire/strip) retaining rings. If you are referring to standard retaining rings with a variable cross section area where in the middle it is the thickest you will probably need Finite Element Analysis.

 

[carter213]

I am referring to constant cross section area. Do you have the formulas available to post them?

 

[israelkk]

It is not just a formula. There are some graphs to select stress correction factors too. This is a few pages chapter with examples and things to consider when you design a retaining rings. Try your local university or old book sellers. I have older version of the handbook even from 1948, 1950 and 1951 and they include the same chaper.

You can purchase the 1955 edition at Alibris

http://www.alibris.com/booksearch.d...k=0&siteID=5Nv03vHgBCI-59Hv7S84LCf.RqlHe1Tffg

for $18. I am convinced it has the chapter in it.

Or the 1950 edition for $22 at Alibris

http://www.alibris.com/booksearch.d...k=0&siteID=5Nv03vHgBCI-f6Y9C2q5dZqALR_7m1q8XA

Or the 1950 edition for $20 at AbeBooks

http://www.abebooks.com/servlet/BookDetailsPL?bi=792424319

 

[desertfox]

Hi carter213

Not the ultimate in snap ring design but it might help you
get an idea of the force.





regards

desertfox

 

[carnage1]

Why do you need to calculate the squeeze? It is very rare to have a snap ring that is actually an interference fit on its shaft, that's not what they are used for.

 

[carter213]

The application is not actually for a snap ring, but the calculation should be useful.

I'm trying to calculate the force required to close the seam gap on a pipe rolled from a flat plate.

 

[carter213]

Question to desertfox or anyone else who would like to answer:

In desertfox's supplied equations, the only material property considered is the modulus of elasticity, which is constant for steel. Why isn't the tensile strength of the steel a factor? Wouldn't a higher strength steel make for a stronger spring?

 

[israelkk]

The stress in the ring need to be calculated due to the deflection and compared to the yield/tensile strength. A weak steel will yield and will have a permanent set under the force. A strong steel will hold and maintain the load without permanent set. The load will be the same because it depends only on the modulus of elasticity and the deflection.

 

[carnage1]

are there any standard equations for roll pins? It sounds like what you have is essentially a giant roll pin.

 

[Cockroach]

You need to look at Curved Beams and some of the associated examples in an advanced textbook for stress analysis. Try the Sidebottom reference.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[GregLocock]

Yup

M/I=E/R=s/y should cover it. R is the extra bend due to M, not the geometrical shape of the ring. You'll need to integrate along the circumference of the snap ring, depending on the loading condition. I think your design approximates to a pair of opposing tangential forces, pretty much, so the bending moment diagram is fairly straightforward.







Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.