Necked-in container body and apparatus for and method of forming same

A method of necking-in a container body comprising the steps of providing a neck-in ring and a center ring;

• said neck-in ring having an inner generally cylindrical guide surface joined to a frustoconical necking surface by a first in-turned radius, an inner cylindrical sizing surface joined to said frustoconical necking surface by an out-turned radius, said sizing surface terminating in a second in-turned radius;
• and said center ring having an outer cylindrical sizing surface terminating in a third in-turned radius;
• positioning said outer cylindrical sizing surface in telescoped radially opposing relation to said guide surface and said necking surface with said third in-turned radius generally radially opposing said out-turned radius;
• and with said neck-in ring and said center ring in said telescoped radially opposing relation effecting relative telescoping thereof with a free end of a container body with the container body being guided into engagement with said first in-turned radius and said frustoconical necking surface and being radially inwardly shaped thereby until a free edge of the container body is generally overlapping said out-turned radius and said third in-turned radius;
• and then while retaining said center ring stationary relative to the container body continuing the telescoping of said neck-in ring and the container body until said second in-turned radius opposes said third in-turned radius to define on the container body a cylindrical end portion of reduced radius terminating in an in-turned terminal portion for facilitating the starting of the cylindrical end portion into telescoped relation with another container component.