Process and apparatus for forming an outwardly curled lip on cylindrical container body

An apparatus for forming containers from a plurality of container bodies, each having an open end and a second end comprising a plurality of radially oriented forming mandrels mounted on a rotatable turret, each of said mandrels comprising:

• a cylindrical shaped portion for supporting the interior of one of the cylindrical container bodies;
• and
• a lip forming die having annular cavity positioned coaxially with and axially spaced from the cylindrical portion of the mandrel, the annular cavity having a generally semi-circular cross-section and including an open mouth and a closed bottom extending radially outwardly of the mandrel and being oriented with the open mouth generally transverse to the axis of the mandrel and in a direction facing the cylindrically shaped portion of the mandrel;
• and
• a frusto-conically shaped portion positioned between said cylindrical portion and said lip forming die, the frusto-conically shaped portion tapering radially outwardly in the direction from the cylindrical portion of the mandrel towards the lip forming die;
• said cylindrical shaped portion of the mandrel, said frusto-conically shaped portion of said mandrel and said lip forming die, forming portions of a substantially smooth and substantially continuous exterior compound surface to allow said deformable container body to slide smoothly axially along the mandrel.

The process for forming an outwardly rolled lip on a cylindrical container body of predetermined diameter having at least one open end and a second end, the process comprising;

• placing said open end of said cylindrical container body coaxially on a cylindrical portion of a mandrel having substantially the same outside diameter as the inside diameter of the cylindrical container body;
• forcing said open end of said container body axially along said cylindrical portion of said mandrel and axially along a frusto-conically shaped portion of said mandrel to thereby outwardly stretch the open end of said container body;
• and
• forcing said stretched open end of said container body into an annular cavity of generally semi-circular cross-section having an open mouth and closed bottom extending radially outwardly of the mandrel, and being oriented with the open mouth generally transverse to the axis of the mandrel and in a direction facing the cylindrical shaped portion of the mandrel, to thereby cause said stretched open end of said container body to roll outwardly to form said outwardly rolled lip on said container body;
• said cylindrical portion of said mandrel, said frusto-conically shaped outwardly tapering portion of said mandrel and said annular cavity, forming portions of a substantially smooth and substantially continuous exterior compound surface whereby said forcing steps of said lip forming process are conducted as said container body slides axially along the mandrel.