Hello
Does anyone have a method to define the perpendicularity and parallelism defects that can be found on compression spring planes?
Kind regards
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Hello
If that's what I think it's called buckling, you can find info here:
http://www.meca.insa-toulouse.fr/~paredes/Ressorts/Compression/Flambage/flambage.htm
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Hello
On the link below, you go to the information section on buckling.
In any case, I advise you to take springs with a close ground finish.
http://www.federnshop.com/Druckfedern/DruckfedernSuche.aspx
After all, a spring is not a guiding element, you can add a shaft in the center or a bushing on the outside.
S.B
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Hello
Thank you for your answers but it's not so much the fambage that interests me (although related to the geometric defect I'm talking about). The springs are not perfectly cylindrical, there are necessarily defects in perpendicularity and parallelism (see attached image).
My question is how to define the acceptable defects on a spring so that the desired function is always fulfilled.
Ground coils theoretically improve these defects, but you have to pay attention to the grinding process, sometimes the cure can be worse than the disease. Indeed I understand (I am not a spring specialist) that grinding can sometimes deform the last coil ...!
Kind regards
ressort.jpg
4 Likes
Maybe try to contact a manufacturer like VANEL, they can give you this information in my opinion.
Hello
Could you specify the function you want to perform exactly?
As @s.b says, you can't use a spring (which deforms by nature) to ensure a precise parallelism between 2 parts for example. You need rigid guidance.
Otherwise, the function of a spring being to provide a force proportional to the displacement, if there is no buckling, this will always be the case.
After that, you can use claw systems that pre-stress the end coils to compensate for this type of defect (in addition to binding your part to the spring). They are sometimes seen on children's rocking games.
on this page Springs - calculation http://www.lynkoa.com/forum/creo/les-ressorts-calcul
I think I gave you what you needed, right?
@+ ;-)
Hello gt22,
The pages you indicated to me allow me to size the springs, it's very practical, thank you for it. Here what interests me is to define the acceptable defect on the spring so that the function of the mechanical assembly is always respected.
The spring is mounted in a flap. The operation is "very precise". What interests me is to calculate the lack of acceptable form, perpendicularity and parallelism so that the function is not degraded. For example, if you push too askew and not perfectly in the axis, the piston "locks" in its housing, resulting in a displacement of the piston that is not continuous.
Kind regards
2 Likes
In fact, the real question is rather at the level of the piston/cylinder mechanism. If you know how to determine the maximum defect that can be tolerated by the piston, you will be able to reflect it on the shape of the spring.
Despite everything, I still think that you shouldn't rely on the spring alone to ensure "very precise" guidance. It would be better to have a rod, linked to the piston, going through the spring to have a long centering and thus avoid piston misalignment.
After that it depends on your space constraints, ... Without more information, it is difficult to be more precise.