The name could be anything.... since the user can edit it.
I would loop thru all features and get the name once the feature type matches. You could look in this macro to see how I got all chamfer names. It will give you an idea how to loop thru and check feature types and get/set their names.
and here is further reference for the GetTypeName2 method
So instead of looking for "Chamfer" you would loop and look for "SheetMetal".
I do not know if it will be an issue for you. But you could have multiple Sheet metal features if you are working with multi bodies sheet metal.