Twisting sheetmetal?

[OTE_TheMissile]

I feel like I might've asked this ages ago when I was active on these forums after first taking this job in 2008, but I can't figure out how to find my old threads from back then...

We have this bracket that we farm out to a laser shop to get cut & bent, and today a fresh batch of them came across my desk for inspection upon arrival. Last time I looked at the print for these was in 2013 according to the revision notes and I remember having to fudge a twist feature for the model using a Loft. The result looks pretty enough but I can't Flatten it with the straight bend and had to do double the amount of fudging for the print to get the layout view.

That was then and this is now, and I'd like to think I'm a better Alibre CAD tech than I was, so is there a less-stupid way of doing this nowadays so the twist can be Flattened like a regular Sheetmetal feature?

 

[HaroldL]

I'd use configurations. One would be the formed sheet metal bracket without the twist so I could get a flat pattern. The second would be a sheet metal bracket with the lofted twist using Part modeling tools. The slight amount of twist is likely not enough to affect the flat pattern development. The amount of forming tolerance also would allow for some variation in the part size with the twist.

I did something similar to this in SolidWorks using the SW Flex tool and was able to produce a part within tolerance. No reason the same technique shouldn't work with Alibre.

edit: I thought I'd upload a couple of images and add that a twist that is greater than what your image shows will affect the flattened part length, how much depends on the amount of twist. It would be beneficial to to make some prototype parts to work out the flat pattern to allow for that twist.

 

[OTE_TheMissile]

Hmm...not exactly what I was thinking but would definitely be an improvement over what I did in 2013. Yeah this isn't anything too fancy, it's a bracket for one of our air horns meant to attach to the front tubes of a motorcycle frame just ahead of the engine (you can just see it above the lower trumpet in the photo); the twist is to get the pair of horns somewhat aligned vertically, for purely visual reasons.

Management looked up the process sheet for these and the twist is made by just sticking the bracket in a vise and cranking on it with a pipe wrench Not our most elegantly manufactured product, I'd say, but it works

 

[HaroldL]

The bracket I did at work with SolidWorks had a 90 degree twist. That's where the Flex tool came into use, since there is no way to twist metal in sheet metal you have to "modify" the model directly. Kind of like your pipe wrench in the shop. It still ends up as a configuration in SolidWorks.

Alibre, not having a Flex tool, is just a bit more work to get the design shaped the way that is needed. If you don't need to show a bend region in the twist then you wouldn't use the 3D sketch guide curves that I did in the images I posted.

And here's a model in case you or anyone else is interested.