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

Discussion in 'Pro/Engineer & Creo Elements/Pro' started by Paolo Zago, Aug 9, 2007.

  1. Paolo Zago

    Paolo Zago Guest

    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
     
    Paolo Zago, Aug 9, 2007
    #1
  2. Paolo Zago

    David Janes Guest

    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
     
    David Janes, Aug 9, 2007
    #2
  3. Paolo Zago

    Paolo Zago Guest

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

    Paolo
     
    Paolo Zago, Aug 10, 2007
    #3
  4. Paolo Zago

    miggy Guest

    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.
     
    miggy, Aug 10, 2007
    #4
  5. Paolo Zago

    Paolo Zago Guest

    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
     
    Paolo Zago, Aug 10, 2007
    #5
  6. Paolo Zago

    takedown Guest

    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.
     
    takedown, Aug 10, 2007
    #6
  7. Paolo Zago

    miggy Guest

    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.
     
    miggy, Aug 10, 2007
    #7
  8. Paolo Zago

    TC Guest

    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.
     
    TC, Aug 10, 2007
    #8
  9. Paolo Zago

    Paolo Zago Guest

    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
     
    Paolo Zago, Aug 12, 2007
    #9
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