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Swept blend on a closed curve loop

nmadsen
1-Newbie

Swept blend on a closed curve loop

Hi,

I am looking for a way to create a model of a lifting sling in a U-hitch where the axis of the attachments in the top and bottom are parallel. This configuration causes the sling to twist as seen below. If you want to visualise it you can try and simulate it with a rubber band and your two index fingers.

I am sure that I could create it by using the pipe feature, which has no icon, but can be found by typing 'pipe' in the search field. I am using Creo 2.0 M130.

The model below is a bit of a mess and I only managed to do it by creating four datum curves and four swept blends. As you can see I have made the section run along the outside of the datum curve in order to check that the model matches the EWL (Effective Working Length) of the actual sling. This is quite important in order to control the complete lifting tool's position in relation to the CoG (Centre of Gravity) so that the riggers can adjust the lifting tool correctly.

I have tried to create a new set of datum curves where the points in the top and bottom are laid out in respect to two different coordinate systems so that (ideally) a new sling could be created just by adjusting the distance between the coordinate systems. This curve can be found in the attached model. The attached model will not accept a swept blend apart from PNT0 to PNT2. Then it fails to regenerate.

Is there anyone out there who has some valuable input? It will be mucha appreciated.

/Niels

Sling U-hitch.JPG


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2 REPLIES 2
mtrautner-2
4-Participant
(To:nmadsen)

Hi Niels,

Here is how I made it work:

1) Merge the 2 curves into 1 curve by creating a copy of the curves

2) Use the newly created curve as the trajectory for the sweep - Note: use the "Sweep" instead of the "Swept Blend" feature

3) Sketch the cross section

4) it will regenerate with warnings:

    - design intent unclear - Creo does not expect that the sweep starts and ends at the same point

    - the trajectory bends to sharply- you may want to consider to adjust the diameter of the sling

5) Ignore the warnings

2016-03-10 08_57_33-VT20002731_SLING_30T_4-5M (Active) - Creo Parametric.jpg

There might be a better and more stable solution out there, but I hope that helps you in the meantime.

Markus

Hi Markus,

Thank you. The sling looks right, but the curve is in the centre of the profile which gives a difference between the curve length (EWL) and the actual length of the inner surface of the sling.

I will try and see if I can use the swept blend feature on a merged curve and then place the cross sections correctly.

/Niels

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