Normal Cutout in Contour Flange not displaying in Flat Pattern

[rpiian]

I'm having an small issue in NX Sheetmetal. (NX 7.5.1.5)

If you can view the attached picture, you can see my process.

I created a cylinder, unfolded it, added a contour flange (on the end), made large cutouts, refolded, unfolded, created the smaller slot cutouts, refolded and tried to create a flat pattern.

The next shot is a picture of the flat pattern. If you notice where I circled, the only cutout not displaying is the small one located ON the contour flange. Everything else worked perfectly.

As you can see the model refolds nicely, but the flat pattern does not display this last cutout on the end.

The flat pattern is to be laser cut. All layers are displayed and all objects are shown. I can give more details of the process if necessary.

Any thoughts or ideas? Thanks so much!

-Ian

 

[JohnRBaker]

I would have to have the actual part file before I could make any comment about what is or what is not happening.

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.

 

[rpiian]

The file is about 6.6Mb, I can't seem to get it to post. Any suggestions? Unless there is another way of getting it to you, I guess I'm out of luck.

 

[rpiian]

Hold the phone, I was able to upload a .rar compressed file. Let me know if it works.

 

[JohnRBaker]

I think I've figured out what's happening, but you're going to have to contact GTAC and have them open a PR since only the Sheet Metal development team is probably going to be able to solve this problem, and then it's still going to require that they make some changes to their code.

What I think that is happening is that the Solid Flattening software (which is used to create the Flat-Pattern from) is not able to handle a 'bend' which is GREATER than 360 degrees. Now under normal conditions there could never be a bend greater than 360 degrees since even using a Contour Flange, as you did for your base feature, would not allow you to use a sketch of a complete circle, it had to be less then 360 degrees resulting in a 'gap' in the solid. However, you proved to be very creative by utilizing a set of cutouts and tabs you ended with a solid bady that actually did go MORE than 360 degrees, but those cutouts prevented you having a self-intersecting solid. And it turns out that when you flattened this solid despite the OUTER loop of edges spanning MORE than 360 degrees that seemed to work OK since I suspect that it just kept laying down the edges since it formed a single loop and besides, you can have a solid WITHOUT an 'outside' loop of edges. But I think when it comes to laying out the interior cutouts that the code assumes that there couldn't be anything more than 360 degrees of face to look at and so when it gets to 360 it just stops. And if you look you will note that that LAST cutout, the one that's coming up missing, it's PAST that 360 degree limit. You can sort of prove that this has nothing to do with the Flat-Pattern part of the code since if you replaced it with either a Flat-Solid feature or even another Unbend feature, you would see the same problem since they are all based on the some underlying 'fattening' code.

Now hopefully the Sheet Metal team can fix this by removing this albeit arbitrary appearing limitation, but in the mean time, at least for your particular example, if you desire was to get a useable 2D profile which could be used as a 'flat-pattern', what I did was to extract a 'Composite Curve' (basically a set of associative curves) from the last time that the solid was flat right after that final set of cutouts was added, but before you have 'Rebent' the model back to its final shape. Since these curves were created with a timestamp before the last 'Rebend' they will be valid and you should be able to use them for what you need. To see what I mean, I've attached an example of my model below.

Anyway, take a look and let me know if this is usable or not.

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.

 

[rpiian]

Thank you John for your input. That was my workaround as well, I was able to manipulate the projection or composite curves to get the correct curves for my laser parts. Just wanted to make sure that I wasn't doing something wrong.

I appreciate you looking into this and yes, hopefully the Sheet Metal team can fix this limitation in future releases. It certainly is not a big deal. I figured it would be icing on the cake if the flat pattern actually worked as I intended it to.

Best regards,

-Ian

 

[JohnRBaker]

But please, contact GTAC and have them open a formal IR/PR as this is the proper way to get issues like this to the right people so that we can enhance/correct these issues.

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.