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J
John.Pryal1-Visitor
1-Visitor
October 2, 2017
Question

Helical Curve

  • October 2, 2017
  • 5 replies
  • 19308 views

Hi all, I think I already know the answer to this question before I even ask it, but here goes anyway. Is it possible in Creo to create a helical curve which follows a profile, in a single feature? A colleague of mine who works with Catia is able to do this. I know I can achieve the same geometry using a helical sweep & intersect with my revolved profile but this is 3 or 4 features versus 1 (2 including the profile curve) in Catia, plus, its much easier to set up. Anyone who also knows Catia probably knows the feature I speak of, its the Helical Curve Definition with 'Profile' selected for the radius variation. Hopefully this makes sense.

 

Regards

John 

5 replies

J
jhaston-31-Visitor
1-Visitor
October 2, 2017

Hi, This can be done using Creo with ease!

Simply create a datum curve defined by an equation! (or in this case three equations).

The only other feature required is a csys.

Creo Helical CurveCreo Helical Curve

I uploaded this model as an example of a helical curve which is defined by three simple parametric equations...

x = 5*t
y = 2*cos(t*360)
z = 2*sin(t*360)

In this case,

The helix is projected along the x axis with pitch = 5 units.
The shape is defined by the equations for a circle in the y-z plane using cartesian co-ordinates, with radius = 2 units.
The helix is right handed.

t is a system parameter which varies between 0 and 1.

Please open the model and explore its interesting properties.

J
John.Pryal1-VisitorAuthor
1-Visitor
October 3, 2017

Thank you for your reply, but this does not answer my original question. I have used this method in the past, it creates a cylindrical helix, it does not follow a profile, it has a constant radius, in your case 2.

I realized after making my post that i can almost achieve my goal but i end up with a redundant surface which i guess isn't the end of the world. I figured I could just use the Helical Sweep feature & sweep a surface in the form of a straight line along my sketched profile, then I have 2 edges I can use for my helix curve.

 

Regards

 

John   

B
BHOoi16-Pearl
16-Pearl
October 3, 2017

You can use relational sweep as shown in the attached file. 

J
John.Pryal1-VisitorAuthor
1-Visitor
October 3, 2017

Thanks for the reply, see my response to the first, I think the same applies. I have attached an image of my requirement & my solution.helix_to_profile.JPG

B
BHOoi16-Pearl
16-Pearl
October 3, 2017

Hi, I tried to solve by adding another equation to the sweep. Is this something you have in mind?

J
John.Pryal1-VisitorAuthor
1-Visitor
October 3, 2017

Thank you for your reply. This is the same as my approach, the image I posted earlier was done in Creo using Helical Sweep just as you show. The only disadvantage to this method is I end up with a redundant surface once i extract my helical curve/edge. In Catia, it appears you can create the helical curve without the surface, so you don't have to deal with hiding it somehow or merging it with other surfaces.

 

Regards

K
KenFarley21-Topaz II
21-Topaz II
October 3, 2017

Seems like the only way to generate this in one feature would be if you can somehow define your profile curve in a simple mathematical way, so you could then calculate the three coordinates based upon the parametric "t" value. The math would be kind of horrendous, and changing the profile wouldn't be fun.

    J
    jhaston-31-Visitor
    1-Visitor
    October 3, 2017

    Hi, I used your method to create a datum curve by projecting the edge of the sweep surface onto the surface of the sweep. I've placed the sweep on a layer and hidden it (I don't see this as a significant drawback). Seems okay and accurately follows the profile. Only two features and relatively straightforward procedure.

    Creo Helical Curve Following a User-defined ProfileCreo Helical Curve Following a User-defined Profile

    I think Ken is dead right about the maths and taking the route using parametric equations. That would be difficult and time very consuming, requiring a different solution for each profile.

     

    T
    TomD.inPDX17-Peridot
    17-Peridot
    October 5, 2017

    The other approach for equations may be a cylindrical equation with R (radius) being controlled by a graph.

    Can we use evalgraph in equations?  ...and if not, why not 🙂

    That's the difference between Creo and Catia... not to mention an exta digit in the price.

     

     

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