A device for forming a closure, including first and second dies for cooperatively forming the closure. The dies come into mutual contact against both sides of an annular disc. The dies form a center hole and cooperatively operate to form a shoulder and skirt on the outer part of the closure. The annular...http://www.google.com/patents/US5152413?utm_source=gb-gplus-sharePatent US5152413 - Bridge design for tamper evident closures
