# US 4,397,668 A · Process and devices for hardening of glassware by ion exchange > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,397,668 A - Document ID: US4397668A - Status: Granted - Kind: A - Application number: 06/266,259 - Filed: 1981-05-22 - Granted: 1983-08-09 - Earliest claimed: 1977-08-08 - Assignees: VEB Wissenschaftlich-Technischer Betrieb Wirtschaftsglas Bad Muskau - Inventors: Siegfried Schelinski; Dieter Patzig; Klaus Heinrich; Bernd Gruger - Web page: https://patentgrep.com/patent/US4397668A ## CPC - C03C 21/002: {to perform ion-exchange between alkali ions (C03C21/005 takes precedence)} - C03C 21/001: {in liquid phase, e.g. molten salts, solutions} - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS ## Abstract The present invention is directed to an apparatus and process for the ion change hardening of glassware by passing the glassware through a stream of molten salt. The glassware may be arranged at different levels on a conveying means, provided with perforations to allow the molten salt to fall from level to level from an overhead salt distributor. The glassware may be positioned on a horizontally spinning rack so that molten salt continuously fills up and empties from the glassware. The molten salt is recycled from the bottom of the apparatus and may be replenished by adding salt to the recycle stream. ## Claims ### Claim 1 An apparatus for hardening glassware by ion exchange, comprising: (A) a molten salt distributor at the top of said apparatus, (B) a series of intermediate perforated salt distributors arranged at discrete intervals underneath said salt distributor (A), to evenly regulate the cascade of molten salt from said initial salt distributor (A), (C) a device for passing said glassware between said intermediate distributors (B) to evenly rinse said glassware with said molten salt, (D) a catch basin for said molten salt underneath said intermediate salt distributors, and (E) means for recirculating said molten salt from said catch basin (D) to said salt distributor (A). ### Claim 2 (depends on 1) The apparatus of claim 1 in which said recirculating means (E) comprises a pipe for recirculating molten salt to said salt distributor (A). ### Claim 3 (depends on 2) The apparatus of claim 2 in which said pipe in said recirculating means (E) additionally comprises an overflow pipe. ### Claim 4 (depends on 3) The apparatus of claim 3 in which said recirculating means (E) comprises at least one of a centrifugal pump, a pneumatic pump, and a compressed air supply to recirculate said molten salt. ### Claim 5 (depends on 4) The apparatus of claim 4 in which said centrifugal pump is submerged in said catch basin (D), with a vertical shaft. ### Claim 6 (depends on 5) The apparatus of claim 5 in which said centrifugal pump comprises (1) a pump housing, (2) a pipe within said housing (1) extending upwardly, and (3) a unit containing rotatable parts comprising an impeller, a pump cover, a drive shaft, and a drive mounting, said unit interchangeable underneath molten salt. ### Claim 7 (depends on 6) The apparatus of claim 6 in which said drive shaft extends through a slidable bearing connected to said pump cover and lubricated with molten salt. ### Claim 8 (depends on 1) The apparatus of claim 1 in which said recirculating means (E) comprises a container lift. ### Claim 9 (depends on 1) The apparatus of claim 1 in which the conveying device (C) comprises a series of extension arms supporting the glassware as it moves through said apparatus. ### Claim 10 (depends on 9) The apparatus of claim 9 in which the glassware is supported in perforated containers which in turn are supported by said extension arms. ### Claim 11 (depends on 10) The apparatus of claim 10 in which said perforated containers each contain between 500 to 5000 holes per square meter arranged equidistantly in staggered rows, said holes from 1 to 5 mm in diameter. ### Claim 12 (depends on 11) The apparatus of claim 11 in which said perforated containers each contain about 2500 holes per square meter, said holes about 3 mm in diameter. ### Claim 13 (depends on 11) The apparatus of claim 11 in which said extension arms are all rigidly connected to a frame which is in turn connected to a running track outside of the apparatus. ### Claim 14 (depends on 11) The apparatus of claim 11 in which each extension arm of said conveying device (E) is provided with an insulating element and labyrinth seal at the edge of said apparatus to retard heat transmission. ### Claim 15 (depends on 14) The apparatus of claim 14 in which each extension arm additionally comprises a removable pallet for supporting the individual containers. ### Claim 16 (depends on 15) The apparatus of claim 15 in which said conveying device (E) additionally comprises a perforated, intermediate plate positioned from 5 to 40 mm above the bottom of each container to support said glassware. ### Claim 17 (depends on 16) The apparatus of claim 16 in which said perforated, intermediate plate is positioned about 20 mm above the bottom of each container. ### Claim 18 (depends on 1) The apparatus of claim 1 in which said salt distributor (A) comprises at least four pieces of pipe in its bottoms for distributing salt. ### Claim 19 (depends on 18) The apparatus of claim 18 in which said salt distributor (A) comprises no more than 80 pieces of pipe to dam up the salt to a depth of at least 20 mm within the salt distributor (A). ### Claim 20 (depends on 19) The apparatus of claim 19 in which said salt distributor (A) comprises about 40 pieces of pipe. ### Claim 21 (depends on 1) The apparatus of claim 1 in the form of a linear furnace for intermittent rinsing of glassware with molten salt. ### Claim 22 (depends on 1) The apparatus of claim 1 in the form of an annular furnace with a series of elements (A)-(E) to incrementally treat glassware. ### Claim 23 (depends on 1) The apparatus of claim 1 additionally comprising an initial means for heating the glassware before the salt rinse and means for cooling the glassware after the salt rinse. ### Claim 24 (depends on 1) The apparatus of claim 1 in which said conveying device (C) comprises a series of rotational racks on which said glassware is mounted with the axis of said glassware perpendicular to the axis of rotation so that molten salt is continuously flowing into and out of said glassware as the glassware rotates. ### Claim 25 (depends on 1) The apparatus of claim 1 additionally comprising meshing aprons to deflect stray splashes of salt back into the catch basin (E). ### Claim 26 A process for hardening glassware by ion exchange, comprising the steps of: (A) arranging said glassware in a plurality of levels on a means for conveying said glassware through a stream of molten salt, (B) passing said glassware through a stream of molten salt, said stream of molten salt originating from jets disposed between 8 mm and 50 mm from each other, causing a rinse density between 5 ml/dm.sup.2 and 500 ml/dm.sup.2, and creating an unbroken salt film between 0.05 mm and 0.5 mm on the outer surface of said glassware, and (C) recycling said molten salt. ### Claim 27 (depends on 26) The process of claim 26 in which said glassware is arranged on said conveying means with openings of said glassware pointing downwardly. ### Claim 28 (depends on 26) The process of claim 26 in which said conveying means comprises a series of rotational racks for rotating said glassware through the stream of molten salt so that the openings in said glassware alternately point towards and away from the oncoming stream of salt. ### Claim 29 (depends on 26) The process of claim 26 in which said molten salt is allowed to creep over the surfaces of glassware not brought directly into contact with said salt stream so that a limited ion exchange may take place on such surfaces of the hollow glassware not directly contacting said salt stream. ### Claim 30 (depends on 28) The process of claim 28 in which said glassware is alternately filled and emptied of molten salt. ### Claim 31 (depends on 26) The process of claim 26 additionally comprising the step of introducing gases and/or vapors to enhance ion exchange on the glassware. ### Claim 32 (depends on 26) The process of claim 26 in which molten salt is resupplied at the step of recycling (C). ### Claim 33 (depends on 26) The process of claim 26 conducted continuously. ### Claim 34 (depends on 26) The process of claim 26 conducted intermittently. ### Claim 35 (depends on 26) The process of claim 26 conducted incrementally.