Springs that change in length?

[JonnyBoy]

I want to create a spring that will adjust in length as my assembly moves. It is the sort of spring you get on a desk lamp. i.e. with hooks on the end and stretches from its neutral position.

Can anyone tell me how i can make a springs length change and the method/ approach i should take?

I'm using Pro/E 2001 Student edition btw.



TIA

 

[charleskim]

Look at PTC's Technical Support Knowledge Base



http://www.ptproducts.com/cs/cs_20/howto/afu309/afu309.htm

 

[gregl]

I did it once with just a simple compression spring, but the same technique will work.

This is what I did:



I assembled the spring part with no geometry into my assembly, aligning the spring axis to my spring pocket axis, and mating one of the spring dtm planes to the bottom surface of my spring pocket.

Then I added an assembly datum in the spring part at an offset of 0 from the surface that will be able to move.

Now your spring part has two planes that represent the desired length of the spring.



In the part I created a dtm curve aligned to the axis with each endpoint aligned with each cooresponding dtm plane. Then I created a surface VSS (pivot direction) using the previously created curve as the trajectory.

In the sketcher I used the TRAJPAR relation variable to create a helical profile with the amount of coils I wanted.

Then you can sweep a protrusion along the edge of the surface to create the actual geometry.



After typing all this out, it sounds kinda long and envolved, but if you've ever made a helix by using a surface VSS and TRAJPAR before, it's not difficult.