Cellular, resinous products and methods and apparatus for making them

Claim 1

THE METHOD OF FORMING A CELLULAR SHEET FROM EXPANDED POLYSTYRENE PEARLS WHICH COMPRISES INTRODUCING THE PEARLS INTO THE FIRST OF A SERIES OF TUNNELS DEFINED BY SHEET SHAPING BELT CONVEYORS, HEATING THE PEARLS TO THEIR SOFTENING TEMPERATURE IN AN UPSTREAM TUNNEL WITHOUT SUBSTANTIAL COMPRESSION UNTIL THEY ARE AUTOGENEOUSLY WELDED TOGETHER INTO A POROUS BODY BY BLOWING HOT GASES THROUGH THE PEARLS IN SAID TUNNEL, CONTINUING TO BLOW HOT GASES THROUGH THE BODY TO MAINTAIN THE TEMPERATURE OF THE BODY, PASSING THE BODY INTO A DOWNSTREAM TUNNEL WHILE AT THE SOFTENING TEMPERATURE AND COMPRESSING IT THEREIN TO ITS DEFINITIVE DIMENSIONS, COOLING THE BODY UNDER COMPRESSION TO SOLIDIFY IT, PASSING THE BODY INTO A FURTHER DOWNSTREAM TUNNEL, AND REHEATING AT LEAST ONE SURFACE OF THE BODY ABOVE THE SOFTENING TEMPERATURE, WITHOUT SUBSTANTIAL COMPRESSION AND WITHOUT RAISING THE CORE OF THE BODY TO THE SOFTENING TEMPERATURE, UNTIL THE SURFACE SOFTENS AND BECOMES SMOOTH, AND COOLING THE BODY.

Claim 2

THE METHOD OF FORMING A CELLULAR SHEET FROM EXPANDED POLYSTYRENE PEARLS WHICH COMPRISES INTRODUCING THE PEARLS INTO THE FIRST OF A SERIES OF TUNNELS DEFINED BY SHEET SHAPING BELT CONVEYORS, HEATING THE PEARLS TO THEIR SOFTENING TEMPERATURE IN AN UPSTREAM TUNNEL WITHOUT SUBSTANTIAL COMPRESSION UNTIL THEY ARE AUTOGENEOUSLY WELDED TOGETHER INTO A POROUS BODY BY BLOWING HOT GASES THROUGH THE PEARLS IN SAID TUNNEL, CONTINUING TO BLOW HOT GASES THROUGH THE BODY TO MAINTAIN THE TEMPERATURE OF THE BODY, PASSING THE BODY INTO A DOWNSTREAM TUNNEL WHILE AT THE SOFTENING TEMPERATURE AND COMPRESSING IT THEREIN TO ITS DEFINITIVE DIMENSIONS, COOLING THE BODY UNDER COMPRESSION TO SOLIDIFY IT, PASSING THE BODY INTO A FURTHER DOWNSTREAM TUNNEL, AND REHEATING AT LEAST ONE SURFACE OF THE BODY ABOVE THE SOFTENING TEMPERATURE, WITHOUT SUBSTANTIAL COMPRESSION AND WITHOUT RAISING THE CORE OF THE BODY TO THE SOFTENING TEMPERATURE, UNTIL THE SURFACE SOFTENS AND BECOMES SMOOTH, AND COOLING THE BODY.

Claim 7

The method of imparting distinctive appearance and dense strong surface layers to sheets of foamed polystyrene, comprising, continuously feeding discrete pearls of fully pre-expanded polystyrene between first and second superposed essentially parallel runs of foraminous belts moving at synchronous speed in order to fill the space defined thereby, while blowing heated gas therethrough, to thereby autogeneously weld the pearls into a porous, incipient sheet of initial thickness, compressing the hot incipient sheet to its definitive form and cooling it throughout below the softening temperature of the polystyrene, rapidly reheating at least one surface of the cooled sheet, to a temperature at which the surface layer of the sheet is softened and flattened by surface tension, while keeping the central internal layers of the sheet below the softening temperature of the polystyrene, and cooling the surface thus reheated while retaining the sheet under compression sufficient to maintain said final thickness.

Claim 8

The method of imparting distinctive appearance and dense strong surface layers to sheets of foamed polystyrene, comprising, continuously feeding discrete pearls of fully pre-expanded polystyrene between first and second superposed essentially parallel runs of foraminous belts moving at synchronous speed in order to fill the space defined thereby, while blowing heated gas therethrough, to thereby autogeneously weld the pearls into a porous, incipient sheet of initial thickness, compressing the hot incipient sheet to its definitive form and cooling it throughout below the softening temperature of the polystyrene, rapidly reheating at least one surface of the cooled sheet, to a temperature at which the surface layer of the sheet is softened and flattened by surface tension, while keeping the central internal layers of the sheet below the softening temperature of the polystyrene, and cooling the surface thus reheated while retaining the sheet under compression sufficient to maintain said final thickness.