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?
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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?spidU9&sfid 7
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Arlin
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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
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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

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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
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