Method and apparatus for sealing the sidewall and bottom seam portions of two-piece containers during manufacture thereof

A seaming means for sealing the side and bottom seams of a two-piece container comprising:

• mandrel means for supporting the bottom blank and sidewall portions of a said container, said mandrel means including forming section means having a peripheral surface shaped to conform to the ultimate sidewall configuration of a said container and including a side seaming area extending longitudinally of said peripheral surface for supporting a lapped side seam of said container;
• seam clamp means coextensive with said side seaming area and extending to a position beyond said forming section means coincident with a desired wet bottom line for said sidewall portion of said container for compressing the said lapped side seam against said side seaming area;
• said mandrel means further including tip means mounted for selective movement toward and away from said forming section means and having a peripheral surface shaped to conform to the ultimate bottom blank and sidewall configuration of the bottom end of said container;
• said tip means in its closest position to said forming section means having a portion of its peripheral surface coincident with and acting as an extension of said side seaming area for compressing a coextensive portion of said lapped side seam against said seam clamp means and in its most extended position having its peripheral surface symmetrically disposed with respect to said forming section means and conformally disposed with respect to the ultimate shape and location of the bottom most portion of said container to be fabricated on said mandrel means;
• and
• said tip means, in translation from said closest to said most extended position progressively compressing said lapped side seam against said seam clamp means from said forming section means to a wet bottom line.

The method of forming a two-piece container from a bottom blank and sidewall blank, on a two-piece forming mandrel having a retractable tip section and a main forming section, comprising the steps of:

• providing a bottom blank on said retractable tip section of said two-piece forming mandrel;
• wrapping a sidewall blank about said main forming section with side and bottom seam sealing areas defined thereon to provide a lapped side seam on said sidewall while maintaining said retractable tip section in its retractable position;
• clamping said lapped side seam against said main forming section and the tip section to partially seal said lapped side seam over the combined longitudinal extent of said forming section and the retracted tip section wherein said tip section in its closest position to said main forming section has a portion of its peripheral surface coincident with and acting as an extension of a side seaming area of said main forming section;
• forming a bottom curl on the lowermost extremity of said sidewall beneath a ultimate wet bottom line of a container to be formed to present said bottom seam area internally of said bottom curl;
• extending said retractable tip section, in continuous juxtaposition with said lapped side seam to progressively seal the latter and said bottom blank with said bottom seam area in said bottom curl;
• and
• compressing said bottom seam area against said bottom blank to provide a sealed bottom seam in said container.