Helical springs with circular and rectangular section
Helical springs with circular and rectangular section
(OP)
Hello Everybody
I was checking the formulas of helical springs, in the machinery handbook of F.jones, but both the formulas are brought in terms of d and D , diameter, not b and w for the rectangular, actually I am not finding the helical springs calculation for the rectangualr section
would you please guide me ?
I was checking the formulas of helical springs, in the machinery handbook of F.jones, but both the formulas are brought in terms of d and D , diameter, not b and w for the rectangular, actually I am not finding the helical springs calculation for the rectangualr section
would you please guide me ?





RE: Helical springs with circular and rectangular section
http://www.roymech.co.uk/Useful_Tables/Springs/Spr...
RE: Helical springs with circular and rectangular section
let me complete my question , for metal forming dies , I think design of the spring is harder , cause there is high velocity of deformation , cold heading , and you dont know the force of the loading , maybe just an approximation, in this case, for helical springs, both circular and rectangular, how can I calculate the stress on the springs ?
RE: Helical springs with circular and rectangular section
RE: Helical springs with circular and rectangular section
RE: Helical springs with circular and rectangular section
Talk to someone with Dayton or Kaller.
RE: Helical springs with circular and rectangular section
RE: Helical springs with circular and rectangular section
Ted
RE: Helical springs with circular and rectangular section
RE: Helical springs with circular and rectangular section
So, what do you hope to gain with your analysis?
Mike Halloran
Pembroke Pines, FL, USA
RE: Helical springs with circular and rectangular section
RE: Helical springs with circular and rectangular section
Thank you so much, that was a great help
while using it, I faced a problem , for the compression helical spring with rectangular section, when I calculate it myself, it give a very higher result regarding to ISO 10243,
there for a green spring of diameter 50, I have the stiffness of 156 N/mm
while I use the formulas i have the external diam = 49mm (should be in fact a bit less than 50), b=5.4, t= 10.9 , n = 6 , free length = 64 mm, Dm = 38.1, k2 = .4 ( with respect to the b*t)
I get the spring constant K = 674.6 N/mm
I just followed the formulations, but I get a very different result
RE: Helical springs with circular and rectangular section
RE: Helical springs with circular and rectangular section
well you are right , but sometimes the spring does not move only cause it is pushed, it moves by the forces of forming. sometimes we use non-standard springs as well. I got involved in reading how to calculate the stiffness of the rectangular springs, and now I found there is a difference, I don't find my mistake, or it's different by formula? I don't know what the catalogue calculations are based on
RE: Helical springs with circular and rectangular section
Heli-Cal couplings appear to be made by a wire-EDM type process to have rectangular sections, so they should obey the classical equations, except for the multiple starts.
It's more common to coil 'rectangular' springs by winding trapezoidal wire or 'double D' wire or 'double D trapezoidal' wire 'the hard way', but the resulting coils don't have truly rectangular section or sharp corners. If accurate equations exist, the spring producers are keeping them to themselves.
Mike Halloran
Pembroke Pines, FL, USA
RE: Helical springs with circular and rectangular section
Right I have a copy of ISO 10243 and all I can see is different spring rates, rod and hole sizes for tooling to compress a spring, which is what ISO 10243 is about:- tooling for compressing springs of rectangular wire.
Further the only reference I can see relating to the 156N/mm stiffness you mention is on page 6 and it states the hole diameter for the spring housing would be 50mm and a rod size of 25 mm and a free length of 64mm but it does not dictate the number of turns, wire section etc, it is up to you to design the spring the ISO is merely quoting a spring which falls into a rate of 156N/mm, with a 50mm housing bore plus a free length.
Now if you study the formula on the Roymech site the dimension 'b' should be the maximum dimension of the material which in your case is 10.9 and t = 5.4, so in the formula I think you have these reversed and in doing so you end up cubing the 10.9 dimension instead of the 5.4 dimension.
If I swop the figures round I get a spring rate of 120N/mm which is much closer to the 156 N/mm you're looking for.
If I do the calculation with t = 10.9 I end up with a spring rate similar to the 674 figure you mentioned.
Incidentally I get K2 to be 0.292 and not 0.4
desertfox
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Helical springs with circular and rectangular section
LCform, take it:
Solution of the problem with Smath Studio (free program similar to MathCAD)
Download Smath Studio
Also look at my PDF file, please.
RE: Helical springs with circular and rectangular section
I looked at the pdf and it states the stiffness is in the order of 563021N/mm which I don't believe is correct, please have a look and tell me what you think.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Helical springs with circular and rectangular section
, (comma) is the decimal mark.
How the world separates its decimals
To the right of the comma there are 4 digits, so the comma, evidently, isn't the thousands separator.
RE: Helical springs with circular and rectangular section
Hi VictorKovtun
We use a full stop here for our decimal points. However even at 56.3 N/mm for the stiffness I still don't agree and what I've found is that the 'D' used in the calculation should be 38.1mm the mean diameter and not the 49mm O.D.
If I run the calculation:-
k= G*b*t^3*k2/(Na*D^3) = 78.3*10^3*5.4^3*10.9*.292/(6*38.1^3)= 118.25N/mm using the 38.1 mean diameter.
k= G*b*t^3*k2/(Na*D^3) = 78.3*10^3*5.4^3*10.9*.292/(6*49^3)= 55.59N/mm using the 49 outside diameter.
The diagrams in the pdf show D/2 as the mean radius, therefore D should be the mean diameter evidently and not the outside diameter which as been used in your calculation.
Note the 118N/mm stiffness is very close to my figure of 120N/mm
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
RE: Helical springs with circular and rectangular section
@desertfox : your attention helped me solve the problem and confusion , great thanks a lot
@Viktor : Special thanks for the software, the best thing for mathematical reports , thanks a lot , also for the help
Best regards
RE: Helical springs with circular and rectangular section
RE: Helical springs with circular and rectangular section
Your both very welcome
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein