Flexible Spring

[purple66sbc]

i am having trouble making a spring i have modeled flexible. i modeled the spring (helical sweep), added it into my assembly, made it flexible, but when i go to change the height, it removes coils rather than compresses the spring, what am i doing wrong here??

 

[AHA-D]

ProE defines pitch, not number of coils so you have to add a relation that changes the pitch value in function of the height.


Alex

 

[sanjeevkar1]

purple you have to give a relation between length of the springand pitch.


so that when the length changes pitch also changes hence keeping the number of coil same.

 

[purple66sbc]

can someone let me know how to do this, i do not have any experience with relations..


thanks, sean

 

[Jonathan21409]

open up relations then double click on the feature and it will show the dimensions that are included with that feature. Then you click on the dimension that you want and write an equation for what that should be equal to you can toggle between dimensions and d1 by a hotkey in the relations toolbar which can be helpful when writing your relations.


in your case you'll want a relation that is set up by pitch we'll say (d3) and height (d4) it will look like


d3=d4/(number of coils that you want) and that should solve your problem

Another helpful thing is before writing your relations you can highlight the dimensions and right click on them go to properties and its the middle tab and you can change the name to whatever you want like height or width so its easier to tell what it is rather then d1.
Edited by: Jonathan21409

 

[sanjeevkar1]

ok purple





make a spring with helical sweep


i used folowing dimensions


length of spring 200 (d637)


diameter of spring 50 (d636)


pitch 5 (d638)


wire dia 5 (d641)


add a parameter name:NO_OF_COILS


type: real number


value 20(you can change it according to your requirment)


now in relation vindow.


select(or type) pitch value = length of spring/ no_of_coils(or the name you gave in parameter)


in my case it is d638=d637/NO_OF_COILS

 

[purple66sbc]

thanks alot, worked perfect!!!

 

[anand_m_s]

Hello Everyone,


Recently I had to create a variable pitch helcal spring model. Also, I had to create two instances of the spring at different compression levels. The variable pitch of the spring are controlled through a parameter "pitch". What I realised during modeling was, although Pro E accepts paramter name for defining the variable pitch, the process is not strictly parametric. If the total length of the spring is changed, one would expect just reduction in the pitch of the spring and not in the no. of turns. But this was what exactly happened with me. Then I realised that, while defining the variable pitch I used the parameter "pitch". Pro E was accpting the numerical value of that paramter at that point of time without maintaining the parametric relationship with the parameter. Hence, once the total length is changed, the numerical value of the parameter "pitch" is alsochanged. However, the variable pitch defined earlier did not get updated; it retained the pitch value corresponding to the previous value of "pitch" parameter. I had to manually re-define the the variable pitch using the current value of "pitch" parameter. Is there any solution to this problem? Or is it a bug in the software? I have tried this in both WF 2 and WF 4 and the results are same.


Also I noticed one more point because of the same problem. I can not use this spring in an assembly as a flexible member. If I choose the total length of the spring dor defining the flexibility, the pitch does not get updated automatically. As the length of the spring defined in the assembly is different from that of the part, the value of "pitch" parameter gets calculated for the length as specified in the part model and not corrsponding to the new flexible length as defined in the assembly.


Is there any ready made solution for these problems? if not, can anybody bring them to the notice of PTC? Thanks in advance.


Anand

 

[kdem]

I've had some partial success if I'm doing this right. However, with a variable pitch spring the relations area little different than those given above. I created a constant diameter variable pitch spring. If I understand what you are doing correctly the problem with the variable spring is that you have two pitch values that need to be specified (in my case) not just one; one at the start of the profile and one at the end. The number of coils seems to be defined by the average of the two start pitch values. From there you can specify the length of the spring and the pitch at one of the ends (I specified the start pitch), and use equations to get the average pitch and from that the pitch value at the other end. You'll need to watch the pitch values.

 

[tobbo]

If you do your spring using VSS instead of helical sweep, then you wont have this problem, the spring will update perfectly. Just one dimension to change when making it fleixble.


(and with a vss spring...you can even "bend" the spring if necessary ....as a bonus.)


Ido all my springs with VSS.


//Tobias
Edited by: tobbo

 

[anand_m_s]

I have no problems in making the variable pitch spring model using the numerical values. Only problem is that the variable pitch graph does not get updated automatically if it is driven by a parameter.

 

[kdem]

But it's not controled by one pitch value which is what you seem to be doing from your description. From what I've found so far you have to specify one of the pitch values and calculate the otherif I'm doing it right. I can post the file so you take a look at what I'm doing to see if it makes sense. Haven't tried the VSS but does it work with variable pitch?
Edited by: kdem

 

[kdem]

Here is my attempt at the variable spring using a helical sweep, relations, and parameters.


2009-06-18_091006_VARIABLE_SPRING.ZIP

 

[anand_m_s]

Thanks a lot kdem. I had missed the last line of the relations given in your model. Its working perfect. I was trying to model a spring with two constant pitch and a transition pitch between them. The requirement was to create a spring with its first and last turn completely compressed and the rest with a different constant pitch. Hence, I had to use variable pich for the transistion between two constant pitch. Here is the snapshot of the spring I made.





Once again, thank you very much


Anand