Method and apparatus for fabricating thermoplastic containers

The method of fabricating a cup-like container comprising the steps of:

• providing a rectangular blank of heat-shrinkable thermoplastic material;
• winding said blank about a generally cylindrical wrapping member to provide a tubular shape with a trailing end portion of said blank overlapping a leading end portion;
• transferring said tubular shape axially on said wrapping member;
• forming a cylindrical sleeve by joining said overlapping end portions of said tubular shape to one another in a liquid-tight seam extending the full length of said sleeve;
• providing an upwardly facing mandrel having an enlarged diameter portion at its lower end, the outer surface of said mandrel having the configuration of the inner surface of the sidewall of said container, and having a circumferentially extending concave rimming die portion located at said lower end;
• heating said mandrel rimming die portion to an elevated temperature;
• telescoping said cylindrical sleeve over said mandrel;
• forcing said sleeve axially downwardly about said lower end and into said mandrel rimming die portion to cause a portion of the lower end of the sleeve to be turned upwardly;
• rotating said mandrel as said sleeve is forced downwardly;
• advancing a complementary rimming die in juxtaposition with said mandrel rimming die portion during rotation of said mandrel to cause said upwardly turned portion to be directed inwardly to form a curled rim;
• subsequently exposing the sleeve to heat while it is in position over the mandrel to cause it to shrink so that the inner surface conforms to the outer surface of the mandrel;
• fusing a bottom closure disc to the end of said shrunken sleeve opposite said rim to form a liquid-tight seal and thus complete said container;
• and removing said container from said mandrel.