How to create a concave bend in SolidWorks

Ok, I am creating a reverse engineering project for one of my
engineering Graphics classes. My project is to recreate a model of
toenail clippers in SolidWorks. I am struggling with how to bend the
front of the clipper blade to recreate the concave appearance of the
original object. I am building the model using the Sheet metal tools.
I think I should be using the Sketch Bend feature, but I am unsure of
how to orient the sketch to bend to the concave shape that I am
looking for. I have asked my instructor, but he is unfamiliar with
using any of the sheet metal techniques in SolidWorks and referred me
to this Site. Does anyone have any suggestions?

 

I believe your problem is that you are trying to create a suface with
compund curvature, also called a non-gaussian surface.

The curved end of the nail clipper is not really bent, but formed.
Solidworks sheetmetal does not support this type of deformation.
You will need to model the part as a solid, without the use of SWX
sheetmetal functions.

Rule of thumb: If you cannot make the part by taking a piece of paper
and bending it without wrinkles, you cannot (properly) model it in SWX.

A little explanation:
First, let's talk about zero-thickness surfaces. There are two types of
surfaces; gaussian and non-gaussian.
Gaussian surfaces can be flattened without any distortion or tearing.
Examples of gaussian surfaces include cylindrical and conical surfaces.
Non-Gaussian surfaces CANNOT be flattened without distortion or tearing.
Examples of non-gaussian surfaces include a saddle shapes and spherical
shapes (think orange peel).

Now, lets extend this to solids.
If we take a gaussian surface and thicken it with a uniform thickness,
we get a solid which can pretty easily be flattened. Calculating flat
patterns from these surfaces is quite easy and can be done with minimal
knowledge of the material properties and bending process. Solidworks
(and other CAD tools) use k-factors or bend tables to determine how the
inner and outer serfaces stretch in relation to eachother accross the
bend.
However, if we take a non-gaussian surface and thicken it with a uniform
thickness, we get a solid that cannot be easily flattened. In order to
flatten this part, the material must either tear or stretch.
Calculating this deformation is quite complex and requires extensive
knowledge of both the material properties and the forming process.
SolidWorks does not support this. Complex non-linear FEA programs are
ususally necessary for this type of sheetmetal modeling.

That probably goes into

For a little more information, check out this link:
http://www.eng-tips.com/faqs.cfm?spid=559&sfid=807

 

How about if you used an 'Extrude Cut' on the flat end? I believe
it would be a secondary grinding type of operation after the part
is bent to give you that sharp edge.

Mike Wilson

 

I just took a look at some clippers and I see the problem. I was
wondering if a Lofted Bend would be of any use here or is it
like trying to put a flange on a cylindrical edge?

Mike Wilson

 

Doesn't seem like it is going to work. The only other option is to create a
forming tool and apply it to the end of the clippers. You won't be able to
unfold this though

Corey