Extension Spring Model in Solidworks 2007
Extension Spring Model in Solidworks 2007
(OP)
I have a model created by someone else of an extension spring. It is comprised of a circular "section" (that is the wire dia), swept over the "path" which has five parts: start loop, start transition, helix, end transition, and end loop. The helix is defined by 'height' and 'revolution' parameters. It appears these are calculated. In my equations sheet I have the following formulas:
HelixHeight@Helix=Length-(2*(OD-(WireDia*1.5)))
and
HelixRev@Helix=INT(FreeLength-(2*(OD-(WireDia*1.5)))/WireDia)
I don't quite understand the equations and what "FreeLength" is?
It is shorter than the length - there is a "FreeLength" plane parallel to the right plane at a distance equal to the value entered for this same named variable in the design table.
HelixHeight@Helix=Length-(2*(OD-(WireDia*1.5)))
and
HelixRev@Helix=INT(FreeLength-(2*(OD-(WireDia*1.5)))/WireDia)
I don't quite understand the equations and what "FreeLength" is?
It is shorter than the length - there is a "FreeLength" plane parallel to the right plane at a distance equal to the value entered for this same named variable in the design table.






RE: Extension Spring Model in Solidworks 2007
http://www.engineersedge.com/spring_menu.shtml
ht
I think your free length is the length of the spring "at rest"--no forces being applied.
Jeff Mowry
www.industrialdesignhaus.com
Reason trumps all. And awe transcends reason.
RE: Extension Spring Model in Solidworks 2007
RE: Extension Spring Model in Solidworks 2007
RE: Extension Spring Model in Solidworks 2007
Most extension springs are preloaded . Their "free" length is shorter than the coil diameter × the number of coils. If effect, if I start to compress a compression spring, it immediately starts to compress. An extension spring has a miniumum extension force below which it does not move.
Your numbers make no sense in a purely mechanical model, but they make a lot of sense if the model is based on an engineering analysis.
This probably is explained in any machine design book you have lying around. If it isn't, you need a new machine design book.
JHG