HOW TO RELAX FLEXED SHEETMETAL PART

michael_mcewen

I've looked at the sheet metal tutorials for unfolding boxes, etc. But, this may need a different approach.  Can anyone show me how to derive a flat part for waterjet cutting from the flexed / in tension parts in my TRUSS part studio: https://cad.onshape.com/documents/7ac2bda8403f47ec99dfd4a2/w/62ca548aab6aaa6334415bca/e/64a9ac196b4b6b4f25dcf740

The 3 "truss" arms (top, right, left) sweep parallel to the construction line in CENTERLINE TRUSS (sketch 1).  The part TOP TRUSS is simple, the curved part is already flat and relaxed. the 2 parts titled RIGHT TRUSS and LEFT TRUSS are identical, and are drawn flexed, and in tension.  I need a convert these parts into a relaxed, flat part.  

Any help will be greatly appreciated. 

Thanks,

Michael

brucebartlett

Hi Michael,  You will not be able to use sheet metal to unfold this as it is a free-form surface. the only option I can think is using a Feature Script the will unfold/unwrap it to a sketch.  I think @konstantin_shiriazdanov may have developed a feature to do this. 

konstantin_shiriazdanov

I beleve in this case my FS won't work because we have a shape of double curvature. Though since the length of the part is far greater then the width you can get approximate solution by measuring the length of inner and outer edges and calculating the mean value and considering the width to stay the same

michael_mcewen

Thanks guys, I'm afraid this is a bit over my head. If the relaxed curve can't be mapped with Onshape, do you have any alternative approaches you could suggest?  I attached some files here of an earlier model I made. The dxf files of the relaxed parts and the approach to arriving there are unknown to me, as I contracted the work out to a CAD guy I've since lost track of. In that case, I started with a hand drafted (sketch shown below) with the curve height mapped every 5".  Any suggestions will be appreciated. suggest?

konstantin_shiriazdanov

in Solidworks there is a feature Flatten surface for things like that

http://help.solidworks.com/2017/english/Solidworks/sldworks/c_flatten_surface.htm

since you are a pro user you could create an Improovement request or internal ticket, OS developers usually pay much attention to what pro users need

NeilCooke

@konstantin_shiriazdanov flatten surface is in solidworks premium only! Took them several years and several attempts to develop so it is no trivial matter. 

@michael_mcewen have you taken a look at ExactFlat in the AppStore?

brucebartlett

Unigraphic's also used to have really nice surface unfold tool, I remember using it back in about 2003 when I did have the pleasure of using the software. I don't think the SolidWorks one came in, till a few versions ago. Obviously, it can be done and I'd love to see something like this, even as an FS in Onshape or even better integrated to sheet metal for this example. 

ExactFlat maybe a good option for now. 

michael_mcewen

Thanks for the tips guys. I'll look into ExactFlat, and I guess I should start an OS request ticket, right?