Method and apparatus for forming can end

A method of forming, from a generally rectangular blank of paperboard having a recess at one corner thereof, a convolute, cylindrical, can body end portion with a relatively smooth surface at the area of side seam overlap to accommodate a relatively snug fit with a plug type closure, comprising the steps of:

• (a) forming the blank into a tubular structure with the recessed corner of the blank underlying another corner thereof;
• (b) inserting a cylindrical mandrel within said tubular structure;
• (c) inserting said tubular structure and mandrel within a hollow, cylindrical, sleeve shaped forming tool which has an opening at one end adjacent said recessed corner;
• (d) applying pressure against said tubular structure and mandrel, in the area where said corners of the tubular structure overlap, by a pressure bar having a head contour matching the shape of said corner recess to compress material of said other corner into the recess of said one corner.