Method and apparatus for forming a can end with controlled thinning of formed portions of the can end

A can end blank is initially cupped and a central portion of the cup is rolled up with an annular portion of the cup being free formed with limited contact with any tooling except to prevent wrinkling, to prevent overextension of the free formed material and to define a final geometry of the free formed material as the forming press reaches a bottom of its forming stroke. The free forming is performed by controlling the motion of a pre-panel punch using a double action piston so that the pre-panel punch is selectively moved between an extended position for formation of a cup of a cupped can end blank and a retracted position for free forming material between a central portion of the cup and a clamped portion of the cupped can end blank.