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JWayman1-Visitor
1-Visitor
October 9, 2013
Solved

Winch Cable wound on drum

  • October 9, 2013
  • 3 replies
  • 6861 views

Using WF4, here.

 

I have been asked to create a model of a cable, wound in a series of layers onto a spool, like a winch cable onto a drum.

The smart money says 'Don't do it', because it will take an age to regenerate. I know that. However, I want to know how to do it anyway. I'm curious like that.

 

I first made a series of curves based on equations like the one shown below:

winch+cable+layer+equation.png

For each layer, I reversed the z direction, incremented the r value and started theta with an offset so I could fake the join between layers using a curve between points, tangent at each end to the spiral curves.

 

 

Once I had a series of coiled layers and joins between them, I tried to Copy, Paste, Approximate, the curves to make the whole ugly mess into a single composite curve. No! Can't do that. No idea why not, but Pro/E insists they should all remain separate curves.

 

So, then I made a series of separate VSS features, one for each layer and one for each joining piece.

That worked after a fashion, I ended up with the model shown:

 

2013-10-09+15_40_59-WINCH_CABLE+coil.png

However, what I would ultimately like to do is to have the whole cable as a singe curve and control the number of layers by making the overall curve length a fixed value. So, if I tell it that 10m of cable is paid out from the winch, I want to have the remainder shown coiled up on the drum.

I therefore tried to write an equation for all the layers. Now, I'm no programmer and I'm doing this in the Pro/Table editor that starts up when you insert a datum curve from equation, so I am working with a bit of a handicap to start with. Clearly, I want to increment my radius by the pitch value and reverse my z direction each time my theta reaches no_of_turns*360. Problem is, Pro/Help tells me I can't use the ABS, FLOOR or CEIL functions in a curve equation.

Is it, therefore, even possible to do what I am trying to do with a single equation?

If not, is it possible to combine all my separate curves into a single composite curve, despite what Pro/E tells me?

 

I look forward to your comments on this interesting little conundrum.

 

 

Cheers,

 

 

John

    Best answer by ptc-5008082

    compcurve.png

    So, the <Shift> key is the one-by-one selection within the composite curve collection and it will only let you select curves that are touching one another.

    In the image the pink and green curves are equation driven and the blue one is a point to point curve with tangency joining them together, I can create them as one composite curve with the <Shift> key.

    Apologies if you know and have tried the following but, you need to be careful with your selection, you need to be picking the entities inside the curve feature... ... you need to (with Smart filter on):

    · Select the first curve – it will turn red

    · Then you need to move your mouse slightly and select again and it will turn into a fuzzy red highlight – as shown.

    · In the bottom right hand corner of the Pro/E interface (near where it says Smart filter) you will see that it says ‘1 selected’

    · Double click on that and it will tell you that is has selected e.g. ‘Curve:F6 CURVE’

    · If it just says F6 CURVE then it is not the correct thing highlighted

    · Now <Ctrl> C and <Ctrl> V to copy and paste and you will be in the composite curve definition and the <Shift> key should stitch them together.

    If this doesn’t work share your model with me and I’ll have a look after work

    3 replies

    T
    TomD.inPDX17-Peridot
    17-Peridot
    October 9, 2013

    I don't know the answer without some more serious equations but I will congratulate you on this accomplishment. Thanks for sharing!

    J
    JWayman1-VisitorAuthor
    1-Visitor
    October 10, 2013

    Thanks, Antonius.

    Today, I have tried a different route: I made a spreadsheet to calculate the r, theta & z values and used it to create a datum point feature, then made a single curve and a VSS to make the cable reel.

    That's fine, but not easy to modify when values change. Extra steps, exporting the points and changing file names, etc.

    I would like to pursue the original method, with a number of separate curves, but I think I really need to be able to combine them all into one single curve, so that I can play tunes on overall length and cable tails, etc., without it all falling over.

    Am I missing a way to combine a number of composite curves into a single composite curve? Come on, Charlotte, you must know the answer to this one!

     

    WF4 (still...)winch cable points curve.png

     

     

    John

    P
    ptc-50080821-Visitor
    1-Visitor
    October 10, 2013

    I'm loving your curves

    (hmmm, that might not sound very politically correct to those not following the thread )

    I think that you issue might be the approximate that you went for?

    Will it allow you to create the curve with exact?

    I have some equation curves, through point curves, composite curves in a model and I can create composite curves of bits of them and then string a bunch of composite curves together into one conposite curve so it is definitely allowed to join multiple composite curves together.

    Approximate aims for curvature continuity and so there is a tolerance that is has to adhere to or some such mathematical nonsense

    D
    dschenken1-Visitor
    1-Visitor
    November 7, 2013

    If you want to make your cable as one piece look at http://communities.ptc.com/docs/DOC-3063

    I devised it for springs, but anything that is wound would work the same.

    J
    JWayman1-VisitorAuthor
    1-Visitor
    November 7, 2013

    Thank you, David.

    I have had a go using this technique and the results look OK, though i say it myself:

    WINCH_CABLE_2.jpg

    I used 3 graphs:

     

    Radius,

    Turns

    and

    Z_Value

     

    RADIUS.jpg

    TURNS.jpg

     

    Z_VALUE.jpg

     

    Each graph was based on a maximum extent of 100.

     

    The curve was constructed using the equation:

    r =evalgraph("radius",t*100)

    theta = 360*evalgraph("turns",t*100)

    z=evalgraph("z_value",100*t)

     

    Add a VSS and Bob's your Uncle...

     

    Thank you to everyone for your help.

     

    John

      P
      ponnarasu1201-Visitor
      1-Visitor
      August 2, 2019

      Can you share the full equation please?

       

      Thanks  in advance.

       

      Regards.

      Ponnarasu Mathialagan

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