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Spring Modeling Help (Solidworks) 1

Helepolis

Mechanical
Joined
Dec 13, 2015
Messages
212
Location
IL
Hi all,

Trying to model a spring with both ends closed-&-ground, using the Helix tool and defined by 'Pitch and Revolution'.
I just can't figure this tool out, how the F the parameters in the table work/linked.
various AI chats didn't help, neither google/youtube, nor the laughable "help" of Solidworks, where only the meaning of the different parameters is explained (thanks for nothing!) and not how the feature actually works.

I've never been so frustrated with a Solidworks feature, at a point of just breaking something just the relive the anger.

Just in case here are the parameters of the spring:
  • Wire Dia. 1.37mm
  • Spring OD 9.83mm
  • Total length (end to end) 19.5mm
  • Total coils 10
  • Active coils 8
  • End Type closed-&-ground
Any reference will be more than appreciated, so I can learn Helix feature (specifically the variable pitch).


Thanks,
SD
 
The YouTube tutorials are pretty obvious; it's more limited than the method I used in Pro/E, now Creo, where the spring pitch equation was described using a curve rather than what appears to be linear interpolations**; it also looks like the Solidworks method is not able to use the overall length as a variable that would allow the spring to conform in the next assembly to the action of the mating mechanisms. This is pretty typical of SW to make something that is easy to get 50% of the way on and then nothing for the remaining 50%. I noticed they manually set the minimum pitch to be larger than the wire diameter, probably to avoid self-intersection. This means the end coils cannot actually be closed as they normally would be for such a spring, particularly with ground ends.

"variable pitch helix solidworks" is what I used to search in google with.

** one interesting variation in Pro/E / Creo was the ability to shift to negative pitch while changing the spring diameter, allowing the spring to wind back down over itself. Never had a need for a spring to do that, but it is something that a wire-bending machine could do. I suppose a pan-cake or clock spring would also be possible, with a pitch of zero and a variable radius smoothly transitioning.

Overall I think that smart tools make users less adaptable.
 
You can also download a spring model from McMaster-Carr and see how it's done.
 
Basically, Mcmaster has used 3 curves to make the spring. 1 for the main body and 2 separate helixes for either end. Then they stich the curves together, sweep the complete curve, and use an extrude cut to grind the ends.

Not too hard to do, and you could still make it parametric. But it does leave a non-tangent joint to the closed ends. Not ideal if you were going to do FEA.
 
Hi all,

Trying to model a spring with both ends closed-&-ground, using the Helix tool and defined by 'Pitch and Revolution'.
I just can't figure this tool out, how the F the parameters in the table work/linked.
various AI chats didn't help, neither google/youtube, nor the laughable "help" of Solidworks, where only the meaning of the different parameters is explained (thanks for nothing!) and not how the feature actually works.

I've never been so frustrated with a Solidworks feature, at a point of just breaking something just the relive the anger.

Just in case here are the parameters of the spring:
  • Wire Dia. 1.37mm
  • Spring OD 9.83mm
  • Total length (end to end) 19.5mm
  • Total coils 10
  • Active coils 8
  • End Type closed-&-ground
Any reference will be more than appreciated, so I can learn Helix feature (specifically the variable pitch).


Thanks,
SD
Why?

Helices are one of the worst things you can do to a large, complex CAD model. There is no need for a helical spring model unless you plan to 3D print it. Just do an array of circles (toruses?). Create a drawing showing the dimensions, the number of coils, and the spring rate. Provide a compression that the spring must recover from when your inspectors test it. The spring manufacturer will not use your CAD model. They will enter your specifications into their tooling to produce the spring.

The spring rate is not only useful to the next engineer who has to work with your stuff. It gives your spring manufacturer a chance to check your calculations.
 
I use Solid Edge instead of Solidworks but I have created springs over the years and have used these methods:
1. Download from McMaster Carr as the fastest route
2. If the spring must be adjustable and move with an assembly, I just model a cylinder. For extension springs, I just create a ring at the ends. If it needs to look "pretty" I put a jpg texture on the surface of the main cylinder. The goal is to reduce the load on the computer.
3. I have never tried the "stacked torus" method mentioned above but that's a great idea. It might even be possible to use a pattern to drive the stacking and adjust the spacing to simulate a deflected spring
4. For torsion springs, I create a ring representing the main body and then create the arms as features or sometimes as an assembly.

Unless necessary, spring coils and screw threads increase the load on the computer and slow things down. Regarding threads, McMaster Carr hardware downloads have threads. I typically extrude a cylinder over them to clean things up. As with springs, a jpg texture can represent the threads if necessary.

Kyle
 
I definitely avoid modeling threads They require very high triangle count burden on the graphics hardware. But helical sweeps have their place and the occasional coil spring is perfectly reasonable.

A few months back I had to model a heavy-wire coil compression spring. It's nice to have and makes the model and assembly drawing look professional.

Variable pitches are much harder. I used to know how to do it in Creo but I have not done it in any other software. I would simplify the pitch as much as you can tolerate looking at.

As long as you don't load your model with hundreds of them it should not be a burden.
 
I use Solid Edge instead of Solidworks but I have created springs over the years and have used these methods...
SolidWorks supports flexible components. I have modelled a coil spring that fits between two flexible faces, although I have not done it for production. There was a fair big of jiggerypokey to achieve this, and I don't know how stable it all is on final models.
 
I only use springs in free state and compressed state for visual purposes only. Sometimes they are used to get accurate mass properties of an assembly.
 

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