Two equivalent springs for one?
Two equivalent springs for one?
(OP)
I've got a compression spring that gives me the function I need, but is a bit too large a diameter. Is there a way for me to figure out how to turn this single spring (21 winds over 6", .188" diameter wire, 1.0" OD) into two springs that would deliver similar force as what I've got, each with less OD? The spring is compressed just under an inch in a normal working cycle.
I'd appreciate any direction as to how to figure this out. Thanks!
I'd appreciate any direction as to how to figure this out. Thanks!
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.





RE: Two equivalent springs for one?
RE: Two equivalent springs for one?
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
K = P/f = Gd^4/(8D^3N) where, G = shear modulus
D = Coil diameter
d = wire diamter
N = number of active coils
Now you can play with the parameters. Ultimately, sounds like you want each spring to have half the stiffness of your current spring. Easy way would be to half the modulus by selecting another material, or double the number of active coils per spring.
Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
RE: Two equivalent springs for one?
It will be interesting to see if I can find a value for each of those variables, since what I've got currently is what "works"--unknown material, but I can otherwise measure the physical dimensions. (This spring resembles a long rocker arm spring.)
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
If you are going to fabricate the spring, a quick metallurgical test will tell you what type of metal...or wave a magnet over it...if it sticks, it's a form of ferrous steel.
The other thought is that if you set K = 2*k, substitute the equation above, you get:
Gd^4/(8D^3N) = 2G1d1^4/(8D1^3N)
Assuming the same material, active coils, and coil diameter leaves you with:
d^4 = 2*d1^4
taking the forth root of both sides gives:
d = 1.19 d1
or d1 = d/1.19
That help a little more?
Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
RE: Two equivalent springs for one?
Thanks!
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
However, you didn't give the work conditions of the spring such as, is it for cyclic use? Then how many cycles are required before fail. What are the environment temperatures? Does it has to be a stainless steel? etc.
http://israelkk.googlepages.com/home
RE: Two equivalent springs for one?
RE: Two equivalent springs for one?
A smaller diameter for the same sort of functional purpose would be great--this spring's life will probably be long-lived in the current configuration.
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
If not you need to make sure that your new spring won't buckle.
You could also look at nesting one spring inside the other. One RH, one LH.
RE: Two equivalent springs for one?
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
RE: Two equivalent springs for one?
Yes, design and analysis of mechanical springs is one of my specialties. But, can you explain what did you mean by "weigh in on this one". English is not my native language and especially not slang. I think I gave enough information even though Theophilus didn't give more info about the current spring material and what it is used for. Anyway, because this is a spring that is cyclical loaded or maybe even under impact loads there is no point to be more specific.
MintJulep
You can not use nested springs 6" long with those diameters the outer spring will buckle and rub on the inner spring even if the inner spring is guided.
RE: Two equivalent springs for one?
By the way, I do not need stainless steel on this. What I've got seems to be some sort of a hard steel--as you said, perhaps a "music wire"--although the wire is quite thick.
Thanks for your help.
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
Where did you get the spring? Is it a custom designed spring or a catalog spring?
RE: Two equivalent springs for one?
So I don't know about the origin of the design--custom or catalog. It has ground ends to meet a flat face (each end).
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
http://www.engineersedge.com/spring_menu.shtml
Thanks for your help, everyone! This should at least get me close enough to create a prototype that will function fairly closely to the spring I've got--but with two smaller-diameter springs.
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Two equivalent springs for one?
http://www.centuryspring.com/
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RE: Two equivalent springs for one?
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.