Inventor 2016, Lofted Flange won't play nice

[Cortman]

I am a 2nd year student and am stuck on a problem that I think Inventor should be able to handle, most likely the problem is me, but I have honestly worked on this for over 3 hours and 2 days, looked at all I could find on line and at school.

The part is fairly simple formed bracket, steel, a stamped part I am revers engineering from a sample. I am trying to create it in Sheet metal, so that I can flat pattern the blank. I will attach a picture of the Geometry and the part that I drew using the 3d loft tool, not the Flanged loft tool in sheet metal. I am also attaching the best I could do with the "Flanged Loft" tool in sheet metal.

The Geometry is pretty simple, I get the feelng that inventor is having trouble creating the part facets in a press brake module, but it would seem that in the press formed output it should be doable? I even tried cahnging the sheet metal defaults to a really thin and soft material thinking it would bend easier with out thickness to model but nothing seems to help it Flange loft.

Any suggestions would be greatly appreciated.

[PaulMunford · Accepted solution]

Hi Cortman,

Inventor will only create flat patterns for parts that can be press braked, not stamped. 

In order to flat pattern, the model must be a developable surface, of consistent thickness and have all edges perpendicular to the faces.

I've created a blog post here on the subject that you might find helpful:

https://graitec.co.uk/blog/entry/autodesk-inventor-sheet-metal-flat-pattern-success-every-time

Your model has edges that are not 90d eg to the faces:

 Fillets with an inconsistent radius, that couldn't be press braked.

 Twist.

 You also have unconstrained sketches with non tangent geometry which could also cause a problem!

I think that your major problem is that you didn't use Inventor's sheet metal tools to create your model in the first place. If the sheet metal tools won't let you create the model you want, then you could take this as a warning that your shape won't unfold.

Your model using lofted flange is better. The reason you have those weird splits across the part is because Inventor is trying to compensate for the twist as shown in the last image.

I've had a crack at an example for you that uses the sheet metal tools. It won't be dimensionally perfect to the shape that you want, but have a look at how I've modelled it and let me know if the technique used helps you?

Cheers,

Paul 

[Cortman]

Paul;

Thanks a bunch for taking time to look at this and completely explain to me why I was having trouble. I reviewed you drawing completely step by step through the model tree and see you using tools that I have never yet learned to use. I will continue to practice using the sheet metal tools when I am expecting a part to be flat patterned. Explaining to me why the part wouldn't model properly is a huge help in my learning to use Inventor properly going forward.

I think that the developers maybe should remove the "Press Formed" output and leave only the "Press Brake" button from the Flanged loft, if as you stated its not an active output, as I spent time trying this as the part seemed it would be developed easily in a press die environment.

Thanks also to JD, and other of you guys who always are so helpful!

All have a great Thanksgiving!

Sincerely; CORTMAN (Randy)

[PaulMunford]

You are welcome Cortman 🙂