Method of and apparatus for forming a double-walled receptacle from thermoplastic sheeting

Claim 1

IN APPARATUS FOR FORMING FROM A SHEET OF THERMOPLASTIC MATERIAL HEATED TO AN ELEVATED SOFTENING TEMPERATURE A DOUBLE-WALLED RECEPTACLE INCLUDING AN INNER LINER DEFINING A SPACE HAVING A CLOSED END AND WALLS EXTENDING THEREFROM TOWARD AN OPENING AND AN OUTER SHELL HAVING WALLS WHICH ARE SPACED FROM THE LINER WALLS AND A WALL ABOUT THE OPENING CONNECTING THE WALLS OF THE LINER AND OUTER SHELL, A SUPPORT HAVING AN OPENING, THE SUPPORT HAVING A SURFACE UPON WHICH THE PERIPHERY OF THE THERMOPLASTIC SHEET IS ADAPTED TO BE SUPPORTED IN A HORIZONTAL PLANE OVER THE OPENING, TOP AND BOTTOM MEMBERS ABOVE AND BELOW THE SHEET WHICH ARE VERTICALLY MOVABLE RELATIVE TO ONE ANOTHER, SAID MEMBERS BEING CONSTRUCTED AND ARRANGED TO MECHANICALLY STRETCH INNER AND OUTER ZONES OF THE SHEET IN OPPOSITE DIRECTIONS PERPENDICULAR TO THE HORIZONTAL PLANE RESPONSIVE TO RELATIVE MOVEMENT OF THE TOP AND BOTTOM MEMBERS TOWARD ONE ANOTHER TO FORM AN OUTER STRETCHED SECTION WHICH IS INCLINED TO THE VERTICAL AND SLANTS INWARD FROM THE PERIPHERY OF THE SHEET TO A SEALING ZONE AT WHICH THE SHEET IS HELD BETWEEN THE TOP AND BOTTOM MEMBERS RESPONSIVE TO RELATIVE MOVEMENT OF THE MEMBERS TOWARD ONE ANOTHER AND AN INNER STRETCHED SECTION WHICH IS ESSENTIALLY PARALLEL TO THE HORIZONTAL PLANE AND AN INTERMEDIATE STRETCHED SECTION BETWEEN THE INNER AND OUTER SECTIONS WHICH IS INCLINED TO THE VERTICAL AND FORMS A V WITH THE OUTER SECTIONS AND SLANTS INWARD FROM THE OUTER SECTION AT THE VICINITY OF THE SEALING ZONE AT THE CLOSED END