Pressure molding process using salt cores and composition for making cores
AssigneePark Chemical Company
InventorsRobert W. Foreman, Michael T. Ives
Life of this patent
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Abstract
A process for pressure molding an article around a hardened salt mold core made from a mixture of relatively low melting temperature salt and sand wherein the core is removed from the finished article by immersion of the article containing the core into a molten bath mixture of the core material thereby to melt the core out of the article, recover the core material, and thus replenish the bath for use in making additional cores. The bath is originally constituted by melting a suitable quantity of a dry premix of the salt and sand.
Claims14
A premix composition for producing mold cores for use in process for making molded plastic articles by forming a moldable material around solidified salt cores or mold cores made of particles of inert material intimately mixed and covered with fused salt comprising the steps of:
- (A) preparing a bath by means of mixing and heating the particles and salt to obtain a homogeneous molten bath mixture:
- (B) forming a mold core of given shape from a portion of the molten bath mixture and cooling and solidifying the formed core;
- (C) pressure molding a moldable plastic material around the resulting solid core to cause the moldable material to solidify and thus obtain a solid structurally rigid molded article containing the core;
- and
- (D) thereafter heating the molded article positioned in or over the molten bath under temperature conditions sufficient to melt and recover the core from the article into the bath but insufficient to adversely affect the article thus freed of the core;
- wherein said premix composition is comprised of:
- an unfused, blended, dry mixture of granulated mold core salt and an inert material selected from the group consisting essentially of:
- glass fibers, carbon fibers and mica flakes.
A process for making molded articles by forming a moldable material around solidified cores made of particles of inert material selected from the group consisting essentially of:
- glass fibers, carbon fibers, and mica flakes, at least one of which is of such physical character as to add tensile strength and flexibility to said cores, said inert materials being intimately mixed and covered with fused salt said process comprising the steps of:
- (A) preparing a bath by mixing and heating the particles and salt to obtain a homogeneous molten bath mixture;
- (B) forming a mold core of given shape from a portion of the molten bath mixture and cooling and solidifying the formed core;
- and
- (C) pressure molding a moldable plastic material around the resulting solid core to cause the moldable material to solidify and thus obtain a solid structurally rigid molded article containing the core.
Dependencies are inferred from the claim text.