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.
1. A process for forming a curl in a neck of a closeable container comprising:
providing an internal form plug having a pre-curl groove that substantially matches a desired shape for a pre-curl;
providing an external forming device that has a form roller having a lip that engages said pre-curl groove of said internal form plug;
placing said internal form plug into an opening in said neck of said closable container against an interior surface of said neck of said closable container at a position on said neck of said closable container where said pre-curl is to be formed;
moving said external forming device so that said lip of said form roller engages an exterior surface of said neck of said closable container and is substantially aligned with said pre-curl groove of internal form plug;
rotating said closable container and said form roller to form said pre-curl in said neck of said closable container;
cutting said neck of said closable container along said pre-curl;
inserting a second internal form plug in a longitudinal, inward direction in said neck of said closable container adjacent to said interior surface of said neck at a position that is displaced in said longitudinal, inward direction from said pre-curl;
aligning an intermediate curl groove on an intermediate curl roller with said pre-curl;
moving said intermediate curl roller in said longitudinal, inward direction so that said intermediate curl groove in said intermediate curl roller engages said pre-curl;
causing rotation between said closable container and said intermediate curl roller so that said intermediate curl groove progressively engages said pre-curl to form an intermediate curl in said neck;
aligning a final curl groove on a final curl roller with said intermediate curl;
moving said final curl roller in a lateral, transverse direction so that said final curl groove engages said intermediate curl;
causing rotation between said closable container and said final curl roller so that said final curl groove progressively engages said pre-curl to form a completed curl in said neck.
2. A system for forming a curl in a neck of a closable container comprising:
an internal form plug that is inserted in an opening of said neck of said closable container, said internal form plug having a pre-curl groove that substantially matches a desired shape of a pre-curl;
an external forming device that has a form roller with a lip that engages an exterior surface of said neck of said closable container and is aligned with said pre-curl groove to form a pre-curl in said neck of said closable container;
a cutter that engages said pre-curl and cuts said neck of said closable container at said pre-curl and removes said neck from said pre-curl;
an intermediate curl roller having an intermediate curl groove that is moved in a longitudinal direction along said neck to engage said pre-curl as said closable container is rotated so that said intermediate curl groove progressively engages said pre-curl to form an intermediate curl in said neck; and
a final curl roller having a final curl groove that is moved in a lateral direction from said neck to engage said intermediate curl as said closable container is rotated so that said final curl groove progressively engages said pre-curl to form a complete curl in said neck.