Envelope (sheet metal)
In craftsmanship, envelope is the double of the edge of a sheet metal part by folding or swiveling . The purpose of the envelope is to increase the stiffness of the sheet, especially with thin sheets. In addition, the envelope creates a rounded edge that reduces the risk of injury (cutting) on the otherwise sharp edge, e.g. B. in lockers or drawers.
The envelope is also known as a double or a fold .