Apparatus for the manufacture of molded articles

Claim 1

MOLDING APPARATUS FOR HEAT AND PRESSURE MOLDING, COMPRISING UPPER AND LOWER MOLD PARTS MOVABLE RELATIVE TO EACH OTHER TO CLOSED CONDITION, AT LEAST ONE OF THE MOLD PARTS HAVING A PLURALITY OF MOLDING CAVITIES, A FLAT FILM OF STRETCHABLE MATERIAL DISPOSED INWARDLY OF A MOLD PART CONTAINING CAVITIES AND ARRANGED BETWEEN SUCH MOLD PART AND A QUANTITY OF A HEAT-HARDENABLE SUBSTANTIALLY LIQUID RESINOUS COMPOSITION, SUFFICIENT FOR ALL OF THE CAVITIES, CHARGED INTO THE MOLDING APPARATUS, A SEALING RING SURROUNDING THE PLURALITY OF CAVITIES AND NORMALLY PROJECTING INTO THE SPACE BETWEEN THE MOLD PARTS, MEANS YIELDINGLY RESISTING THE RETRACTILE MOVEMENT OF THE RING, SO AS TO CAUSE IT TO CLAMP THE PERIPHERAL REGION OF THE STRETCHABLE FILM WITH SUCH PRESSURE AS THE MOLD PARTS APPROACH EACH OTHER THAT SAID PERIPHERAL REGION IS HELD AGAINST BEING DRAWN INTO THE MOLDING AREA WHILE ESCAPE OF RESINOUS COMPOSITION IS PREVENTED, SO THAT SAID COMPOSITION FORCES THE FILM TO EXPAND INTO THE INDIVIDUAL CAVITIES AND LINE THE WALLS THEREOF AS SAID COMPOSITION IS PLACED UNDER INCREASING PRESSURE AS THE MOLD CLOSES, SAID FILM BEING COMPOSED OF SUCH HIGHLY STRETCHABLE MATERIAL THAT IS EXPANDS INTO THE CAVITIES AT THE TEMPERATURE AND PRESSURE OF THE APPARATUS WITHOUT RUPTURE.