UNBENDING SHEET METAL

I have a question for the sheet metal experts here. I have a sheet
metal part with a broad radius. I created the part by drawing the
radius as a thin feature base bend, then I created a cut extrude to get
the contour of the part. What I need is the flat pattern, but the part
will not unbend. I get an error saying the part has features that
cannot be unbent. It is a very simple part, just the sheet metal base
flange and a cut extrude. Any ideas on this? I can email it to anyone
who wants a peek too.
Oh yes, I am running SW2006....

 

Are your cuts perpendicular to the material thickness? If not, that may be
your problem.

WT

 

Picture this: you cut off a section of a tube to create a trough, with
the large open part of the trough aligned toward the top plane. Now
extrude a cut downward from the top plane. That is my situation.
Is there a better way to do this?

 

You need to make your profile, make it a sheet metal part, insert an unfold,
make your cut, insert a fold. The problem is that you told SW to make a
part and then go in with an endmill and make sides of the cut that are
vertical, but in the sheet metal world, the edges of the material would not
be that way unless manufactured that way.

WT

 

I tried this but it wouldn't work. I created the curved base flange,
flattened, then cut out my profile. Then when I unflatten, I lose
everything after the flatten feature. I cannot insert a sketch bend
while in the flattened state either.

Maybe I am going about this the wrong way. What I have is a 55" radius
on a 7.5" x 8.4" sheet metal part. I have a print defining the curved
shape, and I want to create the flat pattern. What is the best way to
go about this?

 

How about sending it to me and I will take a look.

WT

 

You probably need to check "Normal cut" . (I may have that backwards and you
have to uncheck it.) If it won't make the cut with it checked, then you are
probably in trouble and will have to try something like making your part as
a surface and thickening it. Then you should be able to add the sheet metal
feature and unbend it.

Jerry Steiger
Tripod Data Systems
"take the garbage out, dear"

 

I took a look at his part and the problem is that SW wants to have a flat
face to be a reference for the bends. In some instances you can work with
an edge, but it has to be a linear edge. If you use an edge as a reference,
the subsequent fold that is based on that edge will be parallel to that
edge - might make your part skewed & screwed if it creates an axis that is
not oriented properly. I was able to start with a rectangular part, but the
subsequent cuts to form the desired outer shape removed the straight edges,
leaving no reference. The part is formed as only a large radius with no
flat portions, as in rolling a part on urethane rollers to completely radius
the part. I did get something usable (I think) by suppressing the fold
feature to obtain the flat configuration. Interesting exercise.

WT