Process for the production of thinwalled plastic articles

Claim 1

A PROCESS FOR PRODUCING A THIN-WALLED, HOLLOW TERMO-PLASTIC ARTICLE HAVING A BEADED, HOLLOW RIM OF ROUNDED CONTOUR ENCIRCLING A LONGITUDINAL AXIS COMPISING THE STEPS OF SHAPING SAID ARTIICLE FROM A SHEET OF THERMOPLASTIC MATERIAL TO PROVIDE A RIM PORTION HAVING A ROUNDED CONTOUR ENCIRCLING SAID AXIS AND A SUBSTANTIALLY UNBEADED, FLARED SKIRT EXTENDING OUTWARDLY AND BACKWARDLY FROM SAID RIM PORTION, SAID ARTICLE BEING SHAPED BY APPLYING A VACUUM TO DRAW A PORTION OF SAID SHEET OF THERMO-PLASTIC MATERIAL INTO A SHAPING CAVITY, APPLYING A STRETCHING FORCE TO SAID THERMO-PLASTIC MATERIAL TO DIRECT IS INTO SAID CAVITY, AND APPLYING PULSES OF COMPRESSED AIR TO SAID THERMO-PLASTIC MATERIAL TO ASSIST IN DIRECTING IT INTO SAIID CAVITY, CUTTING THE THUSLY SHAPED ARTICLE OUT OF SAID SHEET TO LEAVE AT LEAST A PORTION OF SAID SKIRT EXTENDING FROM SAID RIM PORTION, PROGRESSIVELY BACKWARDLY BENDING SAID SKIRT OF THE THUSLY CUT-UT ARTICLE BY ENGAGING SAID SKIRT WITH A FIRST HEATED DIE RING SURFACE BEGINNING AT THE TREE MARGINAL PORTIONS OF SAID SKIRT AND PROGESSING INWARDLY TOWARD SAID RIM PORTION UNTIL SAID SKIRT IS APPROXIMATELY PARALLEL WITH SAID LONGITUDINAL AXIS, AND THEREAFTER CURLING SAID SKIRT TOWARDS THE UNDERSIDE OF SAID TIM PORTION BY SO ENGAGING THE FREE MARGINAL PORTIONS THEREOF WITH A SECOND, CURVED, HEATED DIE RING SURFACE AS TO PRODUCE A SMOOTH FINISHED BEAD OF ROUNDED, HOLLOW CONTOUR ON THE RIM OF SAID ARTICLE.