NX sheet metal 1

[TechnicalConsultant]

Morning all,

I'm hoping someone can help me on this one. When producing sheet metal parts I dont want the flanges with a minimum bend radius to give me any additional material on the flat pattern. I can change the formula to give me this but if the part has a bend with a radius which is actually important and dimensioned on the drawing I would want the bend allowance formula to work.

In older versions of NX I used a formula which basically said if the expression of inside rad exists and is to the value of 0.01 then give me 0.01 material. If not use the traditional formula. This doesn't seem to work in new versions though.

Any thoughts appreciated.

 

[JohnRBaker]

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.com/museum/

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

 

[TechnicalConsultant]

7.5, the method which used to work was in NX4

Thank you

 

[JohnRBaker]

The Sheet Metal module in NX 4.0 was replaced with the newer NX Sheet Metal module which is based on a totally different scheme for computing such things as the flat-solid blanks and the 2D wireframe flatpattern. While the new module has many more capabilities and functionality, access to the sheet metal 'deformation engine' is not the same as it was in the old module which was 100% developed by the UG/NX team, unlike the current tools which are more like a 'toolkit' with only a predefined set of parameters which can be linked to Expressions and/or which we have control over. Now I'm not saying that the 'toolkit' can't be leveraged to do what you want, it's just that that level of granularity has never been accessed before. Perhaps this could be opened-up more, but it may require some enhancements on the part of the team responsible for the toolkit itself, which while they're part of the Siemens PLM Software organization, they are NOT part of the NX development group.

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.com/museum/

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

 

[TechnicalConsultant]

Thanks for the update John, I will have to try and think of a way round this, the only method that comes to mind is manually moving the 2D geometry of the pattern to suit. It's not too much of an issue when ALL the bends are minimum bend radius as I presume I can set the bend allowance formula to 0? It's just when the part has a combination of minimum bends and precise radii.

I also noticed that you can put 0 as an inside radius now? I don't think we could do that in NX4.

Regards

 

[JohnRBaker]

As I said, overall the new module is more usable than was the old one, as long as you can accept the idea that the toolkit knows exactly how metal is supposed to behave and that's how it's going to create the flattened solids as well as the 2D Flatpattern. But as you have already discovered, since a bend radius of 'zero' is valid (at least as far as the deformation engine is concerned) you might be able to use that feature to accomplish what you're attempting. Note that in addition to a bend radius of 'zero' you can also assign the 'Neutral Factor' on a bend-by-bend case which means that if you make both values 'zero' for a particular bend, that there will be no additional material added to the flatpattern for that bend while those that have normal values will contribute the additional length as you would expect them to. Therefore, is you're willing to edit the bend radius/neutral factor for your so-called 'null' bends (in that they contributed nothing the size of the final flatpattern), this just might work for what you're looking for.

Anyway, I hope that's clear, but give a try and see if this is what you're looking for.

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.com/museum/

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

 

[TechnicalConsultant]

THAT WORKS!

That seems to work a treat, by putting an inside rad of 0 and 0 as the neutral factor the flat pattern is not giving the additional material.

Thank you!

 

[frankbe]

If your sheet metal designs have mostly 90° angles I suggest that you use another approach.

Designing sheet metal parts with inside radius=0 leaves you pretty miserable models and they will never resemble something you will see in real life.

Try the following and see what this brings to you; I think you might like it even better:
Make the inside radius = sheet thickness AND make the neutral factor (NF) = 0.2732

Check out for yourself; The bend radius will be within real life scale AND you will see that the flat pattern dimensions will be the result of the sum of the inside dimensions.

AND if you ever exchange 3D files with 3rd parties they will also prefer this because it will be MUCH easier to import and convert the files to sheet metal.


I hope this helps you.

Greetings,
Frank

2x NX 7.5.4.4 mp2 Mach Design
1x Solid Edge ST2

 

[HercalloY]

This is something i've been wanting to do as well (i mainly have been doing it in other CAD software but also in NX). Its good to see someone else wanting to do the same thing after all these years!

I have come up with a few methods to fudge it in other software but have managed to escape having to worry to much about it in NX as we have multiCAD licenses so i just use what works at teh time. But i am keen to test out the suggestion of BR=0 and kF=0.

As Frank mentions its not as "correct" with a sharp inside radius and given a perfect world i'd love to have a R=t defaulf and get to the same pattern sizes (inside virtual sharp= bendlines). But i have yet to find a real eligant solution in other software we use heavily here. I will play with NX some more to see if i can get it to work how i want (when i get some spare time).

There was a method introduced called "Bend Allowance" and this works how one would expect.... untill you do a fold of anything other then 90 degrees. So back to the drawing board fudging for those kinds of bends! So close

 

[TechnicalConsultant]

Many thanks for the suggestions and feedback, it's good to see I'm not alone in wanting to do this You're absolutely correct that the model isn't an exact replication with a zero inside bend radius, this is done purely to produce a flat pattern without the additional material where a minimum bend radius is required.

I'll keep you all updated with how I get on.