To flatten the entire part, if the Flat-Pattern1
feature is present, unsuppress Flat-Pattern1,
or click Flatten 
on the Sheet Metal toolbar.
You can flatten the bends in a sheet metal part in the following ways:
To flatten the entire part, if the Flat-Pattern1
feature is present, unsuppress Flat-Pattern1,
or click Flatten on the Sheet Metal toolbar.
The bend lines are shown by default when you unsuppress Flat-Pattern1. To hide the bend lines, expand Flat-Pattern1, right-click Bend-Lines, and select Hide.
When you flatten the entire part in this manner, corner treatments
are applied to create a clean, flattened sheet metal part.
To flatten the entire part, if the Process-Bends1
feature is present, suppress Process-Bends1,
or click Flatten on the Sheet Metal toolbar.
To flatten one or more individual bends, add an
Unfold
feature.
For faster system performance, only unfold the bends that
you need for the task that you are performing. For example, when you add
a cut across a bend, only unfold that one bend.