Original Question:
I am trying to model a coil winding: a helical layer on a former, followed
by another helical layer at a larger diameter and so on.
I have figured out the helical layer. I can even get it to increase in
diameter as it goes along the drum. I can't get how to increase diameter and
start winding at the new diameter and in the other direction along the curve
to get the second layer, then increase diameter again for the third, etc.
I hope that makes sense.
Any ideas?
Replies:
1. I don't have a solution, but I do have a recommendation.prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Don't do it. Helical features take up huge amounts of memory.
Whenever I am working on a coil, I just revolve a stack of doughnuts
And nobody ever knows the difference. I once had a 400 part assembly
on my screen. My springs were real springs and my helicoils were real
helicoils.
I had a total of 11 helical sweeps in my assembly. I replaced each with a
stack
of doughnuts and the difference in performance was like night and day.
Now I never use helical sweeps in parts that are going to be assembled into
something else.
2. We do a similar thing for winding fuel hoses onto a drum. One way is to
create curves using equations then link the ends using a curve though
points with added tangency.
Equation
Cylindrical coordinate system
IR='start radius'
OR='final radius'
r=IR + t * (IR-OR)
theta=t * 360 * 'no of turns'
z='height' * t (or pitch * no of turns * t)
Eg 10 turns by 200 high
R=20
theta=t*360*10
z= 200*t
to reverse
R=20
theta=t*360*10
z= -200*t+200
(add 200 to offset start point)
To change direction either use a csys that is reversed or add - in front of
height
3. Draw each "layer" of your coil winding and ignore the layer to layer
transitions for a second. After you have created each layer, go back and
create transitions between each layer (which is a tangent to tangent
transition). I would use a one wrap transition between each layer for ease
of design.
i.e. 4 layer coil would consist of 4 helical sweeps (standard layers) & 3
helical sweeps (tangent to tangent) to combine layers.
Hope that this makes sense.
4. You can do it with a pair of graph features to control the winding helix
and z transitions.
The initial feature will be a curve created by equation, and the equations
will include evalgraph functions.
Once the curve is created. A vss feature can be created on that.
Thanks. everybody, for the help.
As usual, you were brilliant!
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