Method and arrangement for producing knockouts for electrical equipment cabinets

摘要

A method of producing concentric knockouts on a planar portion of sheet metal to be formed into an equipment housing. The sheet metal is successively positioned with respect to punch sets of increasing diameter and knockout portions of increasing size are sequentially cut, but for retaining anchors, to surround previously cut portions. Successive knockout portions are cut by punches moving in opposing directions. The punch sets comprise a cutting punch and an embedding punch. The cutting punch cuts and displaces the knockout in a first direction and the embedding punch of the same punch set moves in an opposite direction to at least partially restore the cut and displaced portion within the surrounding portions of the sheet metal.