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torsion spring mechanism
3

torsion spring mechanism

torsion spring mechanism

(OP)
Hi all,

I'm trying to assemble a torsion spring into my assembly. I would like one end of the spring to be fixed while the other end to be pushed by another part to compress the spring. How can i simulate this mechanism in WF? I'm using a pin connection to assemble the spring and to change the angle of the spring, i'm varying the height slightly. Is this the right way to do it?

Thanks!

gwen

RE: torsion spring mechanism

2
Hi Gwenn

This cannot be directly modeled into Pro/E with your spring. That is, you won't actually be able to model in the spring itself so that it reacts to the applied torque.

Spring entities in the Mechanism Dynamics option allow you to simulate the effect of having an actual torsion spring in your assembly, and allow you to enter in the spring parameters (for a torsion spring, these are the K- factor and the Uncoiled angle). So when you apply loads and such to the rest of your model, the spring entitiy should react accordingly.

Now, assuming that there are two components assembled to the spring, one fixed (part A) and the other one moving (Part B), there should be a pin connection between Parts A and B. The torsion spring which you have modeled can technically be supressed for the mechanism analysis, as you will be simulating it with the mechanism entity.

Once you have the pin connection set up, select Mechanism-->Springs-->New and select the joint axis of the pin connection. You can now enter in the appropriate parameters.

Unfortunately, Pro/E will represent this spring with a tiny icon, so if you are trying to make a movie for the boss, the spring will be missing, and he or she might ask why. The use of these springs is generally for dynamic analysis, and it really speeds things up if Pro/E doesn't have to calculate an elastic deformation in a solid model of a coiled spring, especially since it is simply a matter of the K-Factor anyways.

The spring which you have modeled (judging from some past posts it sounds like youve worked hard on it!) is definitely useful for your drawings and photorenders, but unfortunately there is no easy way to make a movie with it deflecting, if thats what you are trying to do.

P.S... I hope your license allows for Mechanism Dynamics. Otherwise this post won't really help at all :(

Mark

RE: torsion spring mechanism

(OP)
Thank you Mark,

I'm embarrassed that all i ask about is this spring! Anyway, I've done what you suggested and yeah, i got myself a tiny spring icon that doesn't really show in my animation. I tried another method which is make the spring flexible, change the height slightly for it to deflect more, go into animation and take a snapshot, back to standard and change the value again. But this did not work either, it only shows the last deflection.

What is the not easy way you have in mind? I don't need this urgently, actually i don't need it at all, it's just that I've never done an animation and would really like to get one done!

Thanks again!

Gwen

RE: torsion spring mechanism

Gwen,

For a real animation, export all yours parts in Lightwave or 3D STUDIO and there you can morph your spring. This is what I have done for a project.

-Hora

RE: torsion spring mechanism

If you've already made the part flexible, you're half way there

What you need to do next is make a relation that makes the spring deflect by a tiny bit with every regen. So if the dimension is d1, the relation should be

d1 = d1 + .005

(Or minus, whatever you need to do)

What will happen now is every time you regenerate, the dimension will change itself slightly. When you want this to stop happening, you can comment out this relation (add a /* before it).

The next thing you should do is create a mapkey that goes something like:
Regenerate-->Orient to view-->Save a copy-->Save as JPEG.

Running the mapkey will allow you to take a snapshot of the assembly and save it to a JPEG. Since the part changes with each regen, each jpeg will be a little bit different.

This is the time consuming part: Run the mapkey for as many frames as you need. As a guideline, 25 FPS for an MPEG is okay, make sure that however many seconds you want this clip to be times the FPS is how many times you run the mapkey. Save the images a new file every time (e.g. spring001.jpg, spring002.jpg, etc).

You then need to get a program that will let you make an MPEG from a bunch of JPEGs. I've even used Windows Movie Maker, which comes with XP, but I wouldnt go out of my way to recommend that. I've used something else too, but the name escapes me right now. As soon as I remember, I will post it.

Good Luck

RE: torsion spring mechanism

(OP)
Thanks Hora and Mark,

Hora, i read your tips in Thread554-109006 and I'm wondering is it possible for me to do a relation in assembly mode to the pin connection? something like, while part A rotates and pushes spring B, spring B's deflection will decrease. On top of that, add the regenerate relation suggested by Mark, then I'll regenerate every time to sort of show my 'animation'. My parts are small and i don't need alot of angle of deflection. Do you think this might work? I don't have the softwares you mentioned, and I'll try out Mark's method too. (thanks Mark!)

gwen

RE: torsion spring mechanism

Hi Gwen,

The program I told you are for animation purposes only. They are not CAD program. Lightwave was used to create effects in MATRIX.

In ProE you can simulate the spring movement thru relations, as Mark mention above. All relations must be written in assembly mode. When you increment a relation and then regenerate the model will adjust. But you should be careful and add a "IF THEN ELSE" rule when your spring compresses or any other dimensions change value because after multiple regenerations you can obtain a line segment wihch has a 0 length and a error message will be displayed because the geometry cannot be created.

I suggest you to create in backgound a skeleton (use curves and points) and control these curves. Asemble all components at these points and you only have to control the skeleton. Even the length of your spring can follow the mechanism.

It's easy to do it and will give good results.

But in this way you cannot create a movie. If you still want to do it, then you must save your assembly as a TIFF file (with different names, of course) after each regenaration. Then you must put all tiffs together. I think you can use Photoshop ImageReady to do this. Don't forget that for a smooth continuous animation movie you'll need at least 25 frames/second. So you'll have to adjust the increment in your mechanism. And keep the same view angle, pan or zoom.

Good luck,

-Hora

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