Machines for molding plastic products

Claim 1

APPARATUS FOR MOLDING A PLASTIC MATERIAL, COMPRISING: (A) A HOPPER HAVING AN OUTLET; (B) MEANS DEFINING A MOLD CAVITY, SAID CAVITY: (1) CONFORMING SUBSTANTIALLY TO THE SHAPE AND DIMENSIONS OF THE DESIRED MOLDED PRODUCT, (2) BEING DEFINED BY SEPARABLE WALLS AT LEAST PARTIALLY PERFORATED, AND (3) SAID WALLS BEING ENCOMPASSED BY OUTER HOUSING WALLS SPACED FROM THE PERFORATED WALLS; (C) MEANS FOR SELECTIVELY CONNECTING AND DISCONNECTING SAID CAVITY TO AND FROM SAID HOPPER OUTLET; (D) MEANS FOR EVACUATING SUBSTANTIALLY ALL OF THE AIR FROM THE SPACE BETWEEN THE PERFORATED WALLS AND SAID OUTER HOUSING WALLS AND SAID CAVITY, WHILE MAINTAINING ABOVE THE MATERIAL IN SAID HOPPER A SUBSTANTIALLY GREATER AIR PRESSURE FOR A LONG ENOUGH PERIOD OF TIME TO PERMIT AN AMOUNT OF SAID MATERIAL SUFFICIENT SUBSTANTIALLY TO FILL SAID CAVITY TO BE FORCED THROUGH SAID OUTLET, BY SAID GREATER AIR PRESSURE ABOVE THE MATERIAL IN SAID HOPPER; (E) MEANS FOR RESTORING THE AIR PRESSSURE TO SAID SPACE; AND (F) MEANS FOR OPENING THE SEPARABLE MOLD WALLS AND REMOVING THEREFROM THE MATERIAL MOLDED THEREIN.