Best way to model electrical windings?

[ScottAW]

Company I work for now often works with windings, and by that I mean wire wrapped around various shaped objects, creating coils. Not always round tubes, sometimes squares or odd-ball shaped objects.

What I have been doing is to use a trajectory and then creating an extrusion along that, which is just a bunch of circles tangent to one another. I then pattern that normal to the trajectory and that gives me a fairly good representation of the windings.

In reality, the windings aren't wrapped this way, as they are really wrapped at a slight angle, and the ends overlap as they change direction and wrap in the other direction when starting the next layer.

Any ideas on how to best model something like this?

 

[im4cad]

Have you tried to use helical curves instead of a bunch of circles tangent to each other? I hope I didn't misunderstood your question.

im4cad
Pro Design Services, Inc.

http://www.cadproe.com/pds/home.asp

 

[ScottAW]

Well, I've done helical coils before, the only problem is when you get to the end of one "wrap" you must then go out and reverse directions and begin wrapping in the other axial direction.

I figured if I ever got *really* bored one day, I could figure out a formula for the curves to do this. But, it'd be limited to a circle most likely to keep the formulas somewhat simpler.

Basically... I just don't think there is a good way to do this.

 

[im4cad]

A JPEG picture of what you're doing would be helpful, but I think there is no way to attach it here.

im4cad
Pro Design Services, Inc.

http://www.cadproe.com/pds/home.asp

 

[ScottAW]

Remember back in technology class of high school when you had to create your own electro-magnet by wrapping wire around a nail? That's what I'm trying to do essentially, except it's not just one layer of wire, instead when I get to the end of the nail I start wrapping in the other direction over the layer of wires I just wrapped.

 

[mjcole]

You should be able to make a curve or Var Sec Surface that's driven by an equation or datum graphs. For instance you could create the kind of curve you're describing on a simple cylinder by using a curve by equation and driving it as follows.

r=4
theta=360*10*t
z=evalgraph("z_graph",t*10)

Where z_graph would be a datum graph named z_graph with two diagonal lines one up and one down with a fillet between them with x range 10 inches.

For a magnet type shape you would have to use two VSS "Var Sec Sweep" surfaces with straight lines driven by a datum graph for angle.

I'll try to create an example and send you a pic.
Helical sweeps don't work as easily for what I think you're describing.

Michael

 

[ScottAW]

mjcole -

Yes, that sounds about what I'm looking for. I look forward to an example, as I didn't quite follow everything you said. Youl could e-mail the prt file to me, swheeler@fosmiltech.com

Thanks!!!!!!!!!

 

[dgallup]

Generally speaking, it is not necessary to draw every wire in a coil just like it is not necessary to actually model the thread of a screw. I usually just model the envelope of the coil. If necessary, I will model the lead in and out wires as pipes because these have to be bent around lugs and terminals.

Even my electromagnetic FEA is quite happy with the envelope model. It automatically calculates the coil resistance for a stranded coil from the material conductivity and the number of turns. I use the zinc cross hatch pattern in drawings to make the coil look more "stranded".

I can not think of any applications where there is value added from modeling the coil exactly. Even if you want to calculate wire length or resistance, it won't be accurate because the winding tension tends to stretch the wire and deform the round cross section into a hex.