Helical Spring Design - Calculating "true" wire length

[keyser456]

I'm finding different formulas in different places, but I would like to find the one that is generally accepted as correct. I know it's not just:

pi * (mean dia) * (# of coils)

Because this doesn't take into account the horizontal travel. Can someone help me out? Thanks!

 

[desertfox]

Hi keyser456

To get the developed length of the spring you need to develop the length of the helix, this can be done if you know the lead of the helix ie the axial length along the cylinder the wire travels in one turn and the diameter of the spring coils. From here you just use trignometry and the total length of wire in one turn will be:-

a^2 = b^2+c^2

let c = the lead of the helix

b = circumference of the spring coil

so a= sqroot[b^2+c^2]

hope this helps

regards desertfox

 

[mloew]

keyser456,

You can also use the equation for the arc length of the curve.

The link:
Eric W. Weisstein. "Arc Length." From MathWorld--A Wolfram Web Resource.

http://mathworld.wolfram.com/ArcLength.html

Provides the equations for arc length in Cartesian & polar coordinate systems.

Best regards,

Matthew Ian Loew
"Luck is the residue of design."
Branch Rickey

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

 

[metman]

Machinery's Handbook has detailed step by step design for all types of springs with tables and curves. It is very thorough.

Jesus is THE life,
Leonard