Side paper clamping for continuous foam sheet production

Claim 1

A method of continuously producing a cured sheet of foam resin, comprising the steps of: providing a closed mold formed by opposed upper and lower parallel endless conveyor belts having adjacent portions driven in a common molding direction and being held in spaced parallel relationship with respect to each other to respectively form the upper and lower mold surfaces, and further by providing side walls for the mold to close the mold and close the spaces between said upper and lower conveyor belts, with the side walls being driven at the same speed as the conveyor belts in the molding direction; providing a flexible cover sheet extending over the face of one of said conveyor belts that forms said mold and over the face of one of said side walls that form said mold, and with the cover sheet being of indefinite length with one longitudinal edge portion extending in the mold direction and extending out of the mold between the one side wall and the other of said conveyor belts; depositing a mixture of foamable chemicals at the upstream entrance end of said mold on one of said conveyor belts so as to move through a first expansion zone of said mold as it rises to fill the mold and thereafter move through a curing zone of said mold to cure into the foamed product that will exit at the downstream end of said mold; moving said one side wall and other conveyor belt into engagement to clamp there between the longitudinal edge portion of said cover sheet to prevent leakage of the expanding foamable material between said cover sheet and said other conveyor where the cover sheet is clamped; thereafter moving said one side wall and other conveyor belt away from each other to thereby unclamp the longitudinal edge portion of said cover sheet at least within a portion of said expansion zone so that the forces produce by the expanding foamable mixture against the cover sheet may move the cover sheet into close conformity with the adjacent surfaces of the one conveyor belt and one side wall, if needed, while the cover sheet is unclamped and free to move transversely of the molding direction between the other conveyor belt and one side wall while providing a sufficiently close spacing between said other conveyor belt and one side wall to prevent substantial leakage of the expanding mixture from the mold; thereafter moving said one side wall and said other conveyor belt toward each other to reclamp the longitudinal edge portion of said cover sheet between said one side wall and said other conveyor to thereby prevent leakage from between said other conveyor belt and said one side wall, with said unclamping and reclamping being performed with said mold being substantially entirely filled with the expanding mixture at least in a portion of said mold adjacent the unclamped longitudinal edge of said cover sheet; and curing the mixture within the curing portion of said mold.

Claim 2

A method of continuously producing a cured sheet of foam resin, comprising the steps of: providing a closed mold formed by opposed upper and lower parallel endless conveyor belts having adjacent portions driven in a common molding direction and being held in spaced parallel relationship with respect to each other to respectively form the upper and lower mold surfaces, and further by providing side walls for the mold to close the mold and close the spaces between said upper and lower conveyor belts, with the side walls being driven at the same speed as the conveyor belts in the molding direction; providing a flexible cover sheet extending over the face of one of said conveyor belts that forms said mold and over the face of one of said side walls that form said mold, and with the cover sheet being of indefinite length with one longitudinal edge portion extending in the mold direction and extending out of the mold between the one side wall and the other of said conveyor belts; depositing a mixture of foamable chemicals at the upstream entrance end of said mold on one of said conveyor belts so as to move through a first expansion zone of said mold as it rises to fill the mold and thereafter move through a curing zone of said mold to cure into the foamed product that will exit at the downstream end of said mold; moving said one side wall and other conveyor belt into engagement to clamp there between the longitudinal edge portion of said cover sheet to prevent leakage of the expanding foamable material between said cover sheet and said other conveyor where the cover sheet is clamped; thereafter moving said one side wall and other conveyor belt away from each other to thereby unclamp the longitudinal edge portion of said cover sheet at least within a portion of said expansion zone so that the forces produce by the expanding foamable mixture against the cover sheet may move the cover sheet into close conformity with the adjacent surfaces of the one conveyor belt and one side wall, if needed, while the cover sheet is unclamped and free to move transversely of the molding direction between the other conveyor belt and one side wall while providing a sufficiently close spacing between said other conveyor belt and one side wall to prevent substantial leakage of the expanding mixture from the mold; thereafter moving said one side wall and said other conveyor belt toward each other to reclamp the longitudinal edge portion of said cover sheet between said one side wall and said other conveyor to thereby prevent leakage from between said other conveyor belt and said one side wall, with said unclamping and reclamping being performed with said mold being substantially entirely filled with the expanding mixture at least in a portion of said mold adjacent the unclamped longitudinal edge of said cover sheet; and curing the mixture within the curing portion of said mold.