Request for a flexible, flexible object (ehm...)

Hi everyone, I'm new to the newsgroup, did a quick search but could
not find an answer to this question.

I've been using Pro/Engineer for a couple of years, mainly to do
optical devices packaging, but recently I got stuck with this problem,
it's quite difficult to explain, I'll try to be as clear as possible.

Let's say I have a "tubular" object, a sort of pipe with a custom
profile (imagine a string of fixed length with several pearls at fixed
positions), and I want do deform it so that it starts from a given
point and ends to another, tangent to two axis. I can use spinal bend
with a sketched curve and it works fine, but it doesn't keep the spine
length of the object intact, I.E. it adapt the object length to the
length of the path. Is there a solution in Wildfire 2.0 for this
problem?

I can also forget about the sketch and simply define a datum curve
from point A to point B, but not fix its length, and that's the
problem.

And then comes the second part of the problem: in an assembly I have
many of this "strings", and they have to start and end all at
different points. Is it possible to do it in some way? With flexible
components maybe?

I hope someone can give an help

Paolo

 

Hi everyone, I'm new to the newsgroup, did a quick search but could
not find an answer to this question.

I've been using Pro/Engineer for a couple of years, mainly to do
optical devices packaging, but recently I got stuck with this problem,
it's quite difficult to explain, I'll try to be as clear as possible.

Let's say I have a "tubular" object, a sort of pipe with a custom
profile (imagine a string of fixed length with several pearls at fixed
positions), and I want do deform it so that it starts from a given
point and ends to another, tangent to two axis. I can use spinal bend
with a sketched curve and it works fine, but it doesn't keep the spine
length of the object intact, I.E. it adapt the object length to the
length of the path. Is there a solution in Wildfire 2.0 for this
problem?

I can also forget about the sketch and simply define a datum curve
from point A to point B, but not fix its length, and that's the
problem.

And then comes the second part of the problem: in an assembly I have
many of this "strings", and they have to start and end all at
different points. Is it possible to do it in some way? With flexible
components maybe?

I hope someone can give an help

Paolo

This might work, but I haven't tried it: Create a spherical surface, create points on the surface (if references are needed, pick the csys and look for a csys type of spherical, though it probably doesn't matter.) Create datums through the points and tangent to the sphere. Create axes through the point and normal to the planes. Put another point at the center of the sphere. Create a 'through points' curve and pick outer, center and outer points. For tangency each end, pick the axes for start and end points. Only question is: will the length vary.

Here's another one that's been recommended before: use sheet metal because it unbends naturally and retains its length. But, in your case, I'd suggest a variation, an additonal step. 'Wrap' a curve onto the sheetmetal and use this for your trajectory.

David Janes

 

Thank you David, actually I never thought of using sheetmetal for this
issue, I'll have to try it!

Paolo

 

Paolo, If you create the extrusion as a sweep and use insert datum
curve thru points. Use a start and end point and then add points along
the line as you need and use the tweek command to show the variation
or the bending.

 

But the swept extrusion will have a "tube like" shape, I need
something that has also a variable section, imagine for example the
metallic or plastic tube of a shower that has a fixed length and fixed
number of ribs, I'd like to be able to conform it to an entry and exit
point.

Paolo

 

If you want to use flexibility, I would setup 3 flexible dimensions/
parameters: 2 for the position of the endpoint of the tube (you only
need 2 because I'm guessing the bend line will always lie within a
plane), 1 for the tangent angle at the endpoint. You can then create a
sweep profile between your start and end points. I would create the
path using 1 arc tangent to line segments. One line segment should be
verical, and the other line sigment should be coincident with the
endpoint and its orientation controlled via angle dimension relative
to the first segment. If you dig a bit on the synthx.com website,
you'll see that it's possible to dimension the length of an arc.
After you create the arc length dimension, make it reference (non-
driving). Now you at least have the means to measure the total path/
tube length and apply some relatively indepth relations to maintain a
constant path length. It would be up to you to enter endpoint
location and angle that are achievable for a given length tube. I'll
leave the geometry/trig relations for you to figure out.

Regarding your qualms about using a sweep; if your custom cross-
section can be described using equations, you can use a sketch
relation inside a VSS (variable section sweep) instead of a normal
sweep. For example, the equation below would yield a sinusoidally
varying cross-section with N bulges and a max/min radius of (R0+A) and
R0, respectively.

R = R0 + A*sin(N*360*trajpar)

Another option is to use a graph to custom plot your cross-sectional
variation. Seems like a lot of work for such a simple task. I'd ask
for funding to buy the routing package. I'm pretty sure it can handle
things like finite length tubes.

 

Paolo, after you create the sweep (datum curve), just select the
curve, hit the var section sweep icon and sketch all the sections you
need. You can go back and redefine the datum curve to add or remove
more points and tweek it where you need it.

 

Paolo,
If you menage to solve your problem, could you send that part to me. I have
somethnig similar but it never became my top priority and it's still waiting
to be solved...

Can we add attachmants to posts in this newsgroup?

Second part of your problem was that you have an assembly with many of those
parts. It can be done with "make flexibile" command. Make those parts
flexibile and define each one of them independently inside the assembly.

 

Thank you all, I really have some material to experiment now I'll
let you know how things will evolve.

@ TC I don't think we can attach binaries, if I get to solve the
problem (which is not highest priority for me too) I can send you the
parts by email

Paolo