Process for preparing a molded cellular article

Claim 1

A PROCESS FOR PREPARING A MOLDED CELLULAR POLYURETHANE ARTICLE WHICH COMPRISES INTRODUCING INTO THE CAVITY OF A RIGID MOLD A FOAMABLE POLYURETHANE COMPOSITION WHICH IS PERMITTED TO EXPAND UPWARD THEREIN, EMPLOYING A COVER-PLATE FOR SAID MOLD WHICH COVER-PLATE UNIFORMLY RISES IN A SUBSTANTIALLY VERTICAL DIRECTION WHEN CONTACTED BY SAID EXPANDING FOAMABLE COMPOSITION, SAID COVER-PLATE EXERTING A COMPRESSIVE PRESSURE OVER SUBSTANTIALLY THE ENTIRE SURFACE OF SAID EXPANDING FOAMABLE COMPOSITION, SAID COMPRESSIVE PRESSURE BEING FROM ABOUT 10 TO 90 PERCENT OF THE MAXIMUM UPWARD PRESSURE EXERTED BY SAID EXPANDING FOAMABLE COMPOSITION, IMMOBILIZING SAID COVER-PLATE AFTER SAID FOAMABLE COMPOSITION HAS FULLY EXPANDED AND OCCUPIES FROM ABOUT 1.005 TO 1.5 TIMES THE VOLUME OF THE MOLD, APPLYING SUFFICIENT PRESSURE ON SAID FOAM WITH THE COVER-PLATE WHEN THE FOAM HAS BECOME TACK-FREE TO CAUSE THE FOAM, WHILE STILL PLASTIC, TO CONFORM TO THE DIMENSIONS DEFINED BY THE CAVITY OF SAID MOLD AND THE UNDERSIDE OF SAID COVER-PLATE, ALLOWING SAID COMPRESSED FOAM TO BECOME NON-PLASTIC, REMOVING SAID COVER-PLATE AND STRIPPING SAID FOAM FROM THE MOLD.