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flatten out top of spring

L

Lambrusco75

New member
I have made my helical sweep(spring) but I want to flatten out the top of it I know I do cut>sweep do I make a make datum and cut everything above that or is there a rule of thumb as to where I start?
 
Are you asking how to make a cut, or what dimensions to use?



I would just use a cut > extrude > both sides, and pick a datum plane that runs down the center of the spring.
 
TO ADD THE FLAT PORTION TO THE TOP OF A COMPRESSION SPRING - TRY ADDING A 3D CURVE AN SWEEP A PROTRUSION.
 
i donno how to that but i once downloaded a spring model which have everything in one feature.. didn't study how the model is made till now..
 
Can anybody tell me how to make a 3D curve of a spring with flatten ends?

I was checking this forum for a sollution, but I haven't found it yet.
 
A few suggestions to make

have a datum plane at each end seperated by the nominal length of the spring

reduce the pitch in at least 2 steps at each end as Alex (AHA-D) suggested

extend the ends of the spring past each datum plane by about 70-90% of the wire thickness/diameter.

Use the datum planes to cut off the extensions at each end flat at the correct nominal length

View attachment 4235

I recommend you DON'T put fillet radii on the corners of square sectioned springs. This will seriously slow down your model for very little benefit. This is particularly important if you use a lot of springs in your assemblies. I put my springs on their own layer


If you want to get flash you can link all the pitches together via relations so as the spring compresses, the coils get closer together and if you build in the spring constant you can get Pro/E to calculate the loads at any particular compression

View attachment 4236

DB
 
Hi Dell_Boy,


is it possible to put the file you've made here? So we can download it, and see how you've done the whole stuff.


Is it also possible to make a spring with a round wire?


Kind regards
 
Sorry but I am not prepared to publish the spring model above as it stands. What you can't see is that it is derived from a family table that is 3 layers deep and currently contains over 500 instances.

I have far too much time invested in it to simply give it away.

View attachment 4238

Yes it is perfectly possible to create a spring with round wire instead.

DB
 
Hi Dell_Boy,


you can also put here a copy of one instance. I understand that you don't want to put the whole family table here.


Kind regards
 
I haven't downloaded your file, but I think the problem you're facing is pretty generic and one I have faced in the past.


I think you are trying to achieve 'closed and ground ends'. You need to use the variable pitch option on your helix to close the ends. This is a little tricky in Pro/E, because you cannot have the colis overlap as you reduce the helix angle (pitch): you cannot have the pitch less than the wire diameter. The spring pitch curve is trapezoidal in shape in this example: while Pro/E will do some smoothing at the transitions in the pitch, it still isn't perfectly smooth, and you will have to live with this. Once you have achieved the closed ends, you need to create an offset plane at the ground end of each end of the spring, and make a cut there to finish the spring.


When I last did this in Pro/E about seven years ago, the variable pitchoption on thehelix generation feature was not very robust, and it took a number of iterations before the spring would be successfully modeled without regeneration failures. Hopefully the stability of this function has been improved since then.
 
Variable pitch works fine, at least in the last 3-4 years I played with it.


Flatten springs by cutting away top and bottom is - in the field - only done for large springs because it's an extra fabrication step that takes money. Small springs are specified to have last part of the coil flat wounded. Variable pitch helix does not end flat because you can't have zero pitch. If you really want the last end flat you need to "knit" a revolved protrusion to both ends. For assembly sake it is easier to create a datum that is normal to the axis and tangent to the end of the spring (you need a datum curve at the end to attach to).
 
'Flatten' springs in the field, esp. large springs?? I cannot imagine anyone doing this. Most compression springs (large and small) have 'closed ends' because it increases the bearing area at the end of the spring and makesthe areamore uniform, resulting in a better load distribution. While it is true that you cannot have a zero pitch helix, the pitch of the helix can be reduced via the variable pitch option toa minimum. This is where the instability in the feature arises, as Pro/E is picky about just how close to zero pitch you can get. And just how close you can get depends on the geometry of the specific spring, thus the need to putz with it a bit in each example.


I do not mean to suggest this is a fatal flaw in the modeling feature, just a characteristic of it. This is probably due to roundoff errors that get ugly because the pitch is used in the divisor of some equation, thus resulting in a 'divide by zero' problem in the algorithm. The feature probably works a lot better in 64-bit systems than 32-bit systems. Every CAD system I have dealt with struggles with the pitch curve a bit when you try to close the endsof a compressionspring.


To trim the end of the spring (grind it flat), you need a datum plane normal to the helix axis and through a (datum) point at the end of the helix curve: it will not be tangent to the end of the helix curve.
 
Hey Geertdaenen, check your PM Inbox.

I suppose it all depends on your definition of how big is 'large".

Coil springs in car suspension systems are typically made from round wire with closed ends which fit into a shaped receptacles to spread the load more evenly.

Die springs are usually made from "rectangular" wire (small ones with round wire) with closed and ground ends so they are truly flat.

Pro/E will tolerate a SMALL amount of interference in the end pitches before it tosses it's toys out of the cot.

View attachment 4265

By the way, if you really want to you can have pitch less than the wire diameter. The following screenshot was made with a single protrusion (variable pitch helix)


View attachment 4266





DB


Edited by: Dell_Boy
 
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