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Making a Twisted Sheet Metal Part
4

Making a Twisted Sheet Metal Part

Making a Twisted Sheet Metal Part

(OP)
In some product applications we need to make a sheet metal part that has a twist in it. How can we create it?

How should a Twisted Sheet Metal Part be modeled in NX? What feature (other than Free Form Feature) should be used?

Thanks

RE: Making a Twisted Sheet Metal Part

What version of NX are you running?

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/

To an Engineer, the glass is twice as big as it needs to be.
 

RE: Making a Twisted Sheet Metal Part

(OP)
John,
I use NX6.........

RE: Making a Twisted Sheet Metal Part

In modelling I'd just use a 'Through Curves'.
I've not got enough experience with Sheet Metal to suggest a route there.

RE: Making a Twisted Sheet Metal Part

Hmmm Law curves

I managed to replicate your model mmauldin, however law curves are vague and somewhat mysterious. I remember doing something with a sweep where the area was defined by a law curve to remain the same through difference shaped sections like a molded rubber hose on a car for instance, and for some strange reason, the area the area defined by the position of the start point of an associative curve relative to the ABS in the Y direction. What on earth is that all about?

Has anybody got anymore good examples of models that use law curves that I can pick through please?

Many thanks.

Best regards

Simon NX4.0.4.2 MP10 - TCEng 9.1.3.6.c - (NX7.5 native)

www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

RE: Making a Twisted Sheet Metal Part

mmauldin,
  Very nice, but how the heck did you figure that out? I assume that angular law is using the delta y value as the degrees of rotation, but I can't find anything in the documentation that describes it. I'm with JCBCad, any more examples, and/or documentation?
Thanks
  John

RE: Making a Twisted Sheet Metal Part

I understand you asked for a method that did not use freeform features.  The attached part does use ruled surfaces.  This part is fully parametric.  The end blocks may be rotated and/or translated as you wish.  The important associate features are the four studio splines which must be created as degree 4 and are created through the block corner points and tangent (G1) to the edges of the blocks.

If this meets your requirements it is possible to write a journal to automate the creation of the twisted piece.

Frank Swinkels

RE: Making a Twisted Sheet Metal Part

Very impressive mmauldin, it's not obvious how you turn a stright line of length 90mm into a twist of 90 deg. It would be nice if you could elaborate on the law curve method step by step as it seems to be a very efficient way of producing geometry. I note that you used the same method on a coil spring also where the 2d line drives the behaviour of the spring. However I can only describe what it does rather than explain it :)
 

Solid Edge; I-Deas 7 to 12; NX4, NX5 & currently NX6.

RE: Making a Twisted Sheet Metal Part

Have a look at the attached model. How would I create the twist in the middle so it stays nice and tangential using a law curve.

I'm feeling a few shiney purple stars being dished out!!

 

Best regards

Simon NX4.0.4.2 MP10 - TCEng 9.1.3.6.c - (NX7.5 native)

www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

RE: Making a Twisted Sheet Metal Part

Simon,

I'd like to put my 2 cents worth in on your law curves part but I am stuck back here on NX6.

RE: Making a Twisted Sheet Metal Part

Quote (mmauldin):

I'd like to put my 2 cents worth in on your law curves part but I am stuck back here on NX6.
Same here.

RE: Making a Twisted Sheet Metal Part

(OP)
Thanks to all that sent answer to my request!
For mauldin, FrankSwinks and eex23:
Could you gentelmen, please, resend your links for NX5 or NX6? I do not have access at NX7 or NX7.5!
Thanks!

cowski: Thanks a lot for your attachment; It has been sent for NX5 or 6 and worked perfectly!

JCBCad (Mechanical):Thanks for your comment.

RE: Making a Twisted Sheet Metal Part

Attached is an update.  It is NX6.  On layer 1 are the two end pieces.  Layer 2 has the twisted piece using through curves with G2 continuity.  Layer 3 has the twisted piece using through curves with G1 continuity.  Layer 4 has the twisted piece using studio splines and sewn ruled surfaces.

I think the through curves is simpler then the layer 4 option however if you wish to modify the shape to have it closer to reality (if that is important) then this can be done by moving the three internal spline poles for each of the four splines.  You can certainly see the difference between the G1 and G2 examples.

Frank Swinkels

RE: Making a Twisted Sheet Metal Part

Quote:

I originally posted it in another thread about a year or so ago.
OK, so it was more like 2 1/2 years ago: thread561-229687: Twisted Flat Bar

RE: Making a Twisted Sheet Metal Part

Just overviewed all models posted here, and have one question: is it possible to control thickness of twisted zone. If yes, so then it should be possible to convert whole part to sheet metal and have flat pattern, am I right?

 

RE: Making a Twisted Sheet Metal Part

Sheet Metal flat patterns work on nuetral axis length nothing to do with controlling thickness.  The sheet metal bends are thus straightened out using the bend length (along the nuetral axis) which is approximated as I am sure you know.  Now if you look at the twisted section you will note considerable difference in length between the centre and the external edges.  This requires plastic flow both in tension and compression across and along the twisted section as compared to a bend when we have uniform plastic flow across the bend section.  There is therefore no simple flat pattern method for the twisted part. In other words going from a CAD model to a valid flat pattern is not possible for such a piece.  If you have data for a range of twisted pieces it is possible to write an algorithm to modify the twisted part to an appropriate flat pattern.

Frank Swinkels

 

RE: Making a Twisted Sheet Metal Part

The files I submitted are in NX6.  We're a little behind the times.  

As for controlling thickness, the models I submitted are created by first making a sheet and then adding thickness, so they are by default, within the tolerance setting, controlled for thickness.

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