US Patent 7503741 Formation of a curl in a unitary closable container

Disclosed is a device and method for forming a curl in a closable container. A process of forming a pre-curl is used, which is followed by a second separate step of forming the completed curl. The two-step process provides for higher tolerances with respect to the shape of the curl that allows the curl to be used as a sealing surface for a recloseable metal bottle. A three-step process provides for even greater tolerances and reduces longitudinal forces by completing the curl using lateral forces. Also, a die curler is disclosed that has an eccentric motion that forms a curl in a single progressive curling process.