Issues Creating Flat Pattern from Part File

[tmoney315]

Hello everyone,

I'm somewhat new to Inventor and don't seem to understand working within the sheet metal environment. I assumed that this part would lay out flat completely without too much fuss. I modeled this part quickly just as an example. It's similar to the one I am having issues with, but this is much more simple. I originally designed the part in the modeling environment and then hit "convert to sheet metal." I thought that once I was there, I could use the "flat pattern" button...but apparently not so. The end goal is to have a handful of flat pieces to be cut out on a laser cutter and then welded together to make a bumper. However, it seems that only one face lays flat. Is what I'm trying to accomplish simply not possible? I don't see it as being that difficult of a procedure...I'm using Inventor Pro 2019.

[TheCADWhisperer]

I haven’t taken a look at the file yet - 

did you set the Thickness.

is your part uniform thickness.

are your bends cylindrical or conic?

[tmoney315]

Thickness should be uniform at .1875" and the radii are cylindrical.

[CadManagerMoffatNZ]

tmoney

you will need to model this as separate parts for the front and top/bottom edges.

Inventor 2019 will not unfold - flat pattern the compound curves your model contains.

[TheCADWhisperer]

I took a look at your part.

It is not uniform thickness.

It is missing obvious bends.

[CadManagerMoffatNZ]

here is the front part with a working flat pattern.

[tmoney315]

Where is it not uniform? If you were to seperate the top, bottom, and front wrap around piece they all measure .1875" thick. And I guess my question is if the flat pattern button serves as a "do it all" solution. Or am I supposed to add bends to the aprt aftrer converting it to sheet metal? Because it doesn't seem to want to let me do that. Looking for some guidance here as I don't know much about working in the sheet metal environment.

[tmoney315]

So it IS possible to have those different sized radii on the same flat pattern! I'm sorry if this is something very basic, but please explain how you can make those other bends and curves on the ends lay down flat. When I try to make the flat pattern, I can only get the wide front face to flatten out.

[CadManagerMoffatNZ · Accepted solution]

In this release of inventor the un-folder is "planar" in the way it creates the flat pattern.

So for you bumper example it can only unfold the "front" (wide) face.

When you introduce the top and bottom flanges the curves become compound and the current un-folder will not work.

Another way to think of planar unfolding is can the part you are modelling be folded up on a standard brake press. 

Yes you can have different radii on a part as long as the solution is "planar".

i model parts daily using standard fold (brake press) and large radii roll form (step bending).

[tmoney315]

Interesting. Thank you for your help and input. So I guess I'll just need to use the split tool to remove the top and bottom pieces to have them laser cut as needed. Then make the necessary adjustments to the bends on the front one to lay it out flat to be cut out and then have it rolled on the press?

[CadManagerMoffatNZ]

Yes that sounds about right.

If i can find a few spare minutes i will remodel the example you have posted in a more correct (sheet-metal) format as a bit of a rough guide for you.

Sheetmetal comes easy when you have been doing it for 34 years!!!!!

[tmoney315]

If you don't mind, that would be great. I have gained most of my experience in 3D modeling using Solidworks primarily. The company I just got a job with uses Inventor and I've been picking it up fairly well. Unfortunately, I don't have hardly any sheet metal experience in either program...So I'm currently trying to absorb any advice, tricks, and Youtube videos I can come across.

[tmoney315]

Another question I have for you is if a press brake can run off of 3D model geometry alone. The real bumper I am working with has a spline that controls the curvature of the front face. Will it be possible for a press brake to get the measurement information from the 3D file for the bending? Or will I need to remake it with a measurable radius across the front?

[CadManagerMoffatNZ]

Here is a bumper that i have thrown together during my lunch break.

It illustrates how i would attack this problem to give a manufacturable part albeit with some fabrication. Others may do it differently however.

To answer your second question we have software that we can drive our press brakes directly off the 3D model we produce. It will then set back gauges and shut heights to produce the part and even display a graphical fold sequence on the screens on the press brakes to assist the operator. It would depend on what you have in house or your sub-contractor network can utilize to realize your designs if a 3D model file can be used in downstream manufacturing.

[tmoney315]

Thanks so much for your help Daren. You cleared up quite a few of my questions and have given me a great starting point. After viewing your workflow, I'm quickly realizing that it's much easier to just model within the sheetmetal environment from the very beginning rather than trying to convert a part file to sheetmetal.