Patent ID: 7073365

Claim:
A method of reducing the diameter of a sidewall of a seamless unitary metal container body having a sidewall, an endwall at one end of the sidewall, an open end at an opposite end of the sidewall, and a longitudinal axis extending between the endwall and the open end, which method comprises: introducing a knockout element into the container body through the open end, providing a forming die shaped to reduce the diameter of the sidewall of the container body when the open end of the container body is forced therein to produce a neck portion of reduced diameter on the container body, driving the open end of the container body into the forming die, retracting the knockout element through the neck portion as the neck portion is formed, and removing the container body from the forming die and knockout element; wherein at least one of the driving of the open end of the container body into the forming die and the movements of the knockout element are carried out by at least one linear reciprocal prime mover arranged to create movement and force in the direction of the longitudinal axis of the container body under computer numerical control, thereby enabling at least one of said driving and movement to be optimized for said container body and said neck portion formed thereon.