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Rectangular helical sweep feature

Re: Rectangular helical sweep feature

Evalgraph has been covered in depth here in the community.

The idea behind it is to draw an X-Y graph where X is your origin (path zero to one) and Y is the value at that location on the path.

Your graph will look like a stair-step.

Re: Rectangular helical sweep feature

Attached is an example of how to do this using evalgraph.  After you have setup a graph, you setup the relation in the section for the sweep.  I have also set a relation at the part level to set the pattern distance to equal the value set by the graph.

Re: Rectangular helical sweep feature

Hello to all,

first of all thanks for all that help here!!!! Even there is still no perfect solution yet.

Antonius Dirriwachter‌ thanks for your explanation about how is a evalgraph working.

I think I have understood the function with the evalgraph and the trajpar. As far as I can tell. "I'm still a rookie about this"

, I tried to understand the example what you have attached. So far so good. But your example has one serious error.

The slope consists of 2 Sweep's and not one. AND the blue Sweep is completely flat along the curve. Only the green sweep has the slope.

evalgraph_trajpar.jpg

After this diagnosis I tried to use one curve (Skizze 1) where the profile is pulled along. But this only works when the start and end of the curve have a minimum distance.

curve_distance.JPG

However, this is technically wrong. It must be closed and only separated in one place.In order for the following curve (patterned) to be combined with the original curve. And no intermediate piece has to be patched.

>> However, if the curve is closed and only separated at one point, the sweep will fail. << I'm getting confused.

Still waiting for a good solution.

Re: Rectangular helical sweep feature

I used a normal sweep together with trajpar it should give the required geometry. to my suprrise the sweep feature in Creo 2 doesn't allow closed curves having a trajpar parameter

Re: Rectangular helical sweep feature

Correct, I set it up as 2 sweeps, a flat section and a sloped section, as is shown in the black and white image you attached. If you're trying to do it as a constant slope it's the same process.  Attached is one with a constant slope.

Re: Rectangular helical sweep feature

The original angles the wide section; and it steps only in one of the two short sections.

This is the reason an evalgraph will work well.  It is not a constant rate of "anything" which trajpar can utilize.

However, you can bury the evalgraph in the trajpar statement.

It appears that the angle of the "blade" is constant.  Correct me if that is not true.

Re: Rectangular helical sweep feature

Antonius Dirriwachter

you are absolutely correct with your explanation about the angles definitions in the white picture from the first post.

Shame on me, about the white example picture. It was only a fast screenshot, what should show what I like to have.

And I didn't realize which section (area) has the slope. I thought it is linear or. constant. My mistake, sorry about that.

And yes you are right, the "blade" is constant.

And I want to have a linear or constant slope over the complete sweep Feature.

Re: Rectangular helical sweep feature

Oh, that changes things a lot

Re: Rectangular helical sweep feature

This is probably another way to model the geometry. It requires more steps  but I hope it does give you what you wanted. I apologize if I have misunderstood the intent.

Capture.JPG

Re: Rectangular helical sweep feature

I am looking at your model and wish to make a couple of comments worth investigating.

This is the right way to do something when you have to know the system does what you expect.

In the end, the analysis tools provided by Creo will bring out a lot of little things that take a moment to understand.

1st comment is that the section needs to be normal to the trajectory is you are forming materials...

   which causes an unwanted twist to the geometry normally not noticed on round sections.

This is where that "trust" issue with the system comes in.  If it is "analysis critical", then you would have to manage the twist also.

We have done that in other posts, but in short, ...

   you create a guide curve for the Sweep feature as a chain (second pick) just to keep your section oriented throughout the sweep.

Also, I am no fan of copy geometry.  This one easily patterns.  If the sweep was solid, it would all merge automatically too.