Method and apparatus for heat sealing a free marginal edge of an upstanding columnarwall to a peripheral edge

Claim 1

APPARATUS FOR HEAT SEALING A FEEE MARGINAL EDGE OF AN UPSTANDING COLUMAR WALL OF THERMOPLASTIC SHEET MATERIAL TO A COEXTENSIVE ABUTTING PERIPHERAL EDGE OF AN OVERLYING THERMOPLASTIC SHEET-LIKE TOP WALL SPANNING SAID COLUMNAR WALL AND HAVING A MARGINAL CONTOUR CORRESPONDING TO THE CROSS SECTIONAL CONFIGURATION OF SAID COLUMNAR WALL AT SAID FREE EDGE THEREOF TO FORM A FUSED SUBSTANTIALLY SMOOTH BUTT JOINT BETWEEN CORRESPONDING CONTIGUOUS ABUTTING AND REGISTERING EDGE PORTIONS OF SAID COLUMNAR WALL AND SAID TOP WALL, AND TO PROVIDE A UNITARY OPEN-ENDED CONTAINER; SAID APPARATUS COMPRISING COOPERATING INNER AND OUTER ELECTRODES OF A HIGH FREQUENCY ELECTRONIC PLASTIC WELDING CIRCUIT, AND MEANS TO APPLY HIGH FREQUENCY CURRENT TO SAID ELECTRODES; SAID INNER ELECTRODE DEFININ A CANNISTER HAVING HORIZONTALLY EXTENDING VERTICALLY SPACED PARALLEL UPPER AND LOWER PLATENS AND A VERTICAL WALL EXTENDING THEREBETWEEN AND RADIALLY INWARDLY OF SAID COLUMNAR WALL OF SAID THERMOPLASIC SHEET MATERIAL EXTENDING THEREAROUND; SAID OUTER ELECTRODE COMPRISING AN INVERTED DISH INCLUDING A DEPENDING MARGINAL FLANGE HAIVNG A VERTICALLY EXTENDING INNER ANNULAR FACE WHICH IS FLAT IN SECTION;