Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/04—Casings; Linings; Walls; Roofs characterised by the form, e.g. shape of the bricks or blocks used
  • F27D1/06—Composite bricks or blocks, e.g. panels, modules
  • F27D1/08—Bricks or blocks with internal reinforcement or metal backing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/14—Closures
  • B22D41/22—Closures sliding-gate type, i.e. having a fixed plate and a movable plate in sliding contact with each other for selective registry of their openings
  • B22D41/28—Plates therefor
  • B22D41/30—Manufacturing or repairing thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/50—Pouring-nozzles
  • B22D41/52—Manufacturing or repairing thereof

Definitions

• the present invention relates to a co-molding process for producing co- molded, chemical-bonded, canned refractory articles.
• a refractory composition containing a refractory aggregate and a chemical binder is co-molded under relatively high pressures to form the article followed by drying at temperatures sufficient to cure the chemical binder but not at temperatures high enough to be detrimental to the metal can.
• the present invention relates to a process for producing co-molded, canned refractory nozzles and co-molded, canned refractory slide gate plates.
• One of prior art methods for producing canned refractory articles comprises mixing a refractory aggregate with a chemical binder or wetting agent to fo ⁇ n a refractory composition of pressing consistency. The composition is pressed to shape the article. The article is sized, dried, and then fired to form ceramic bonds. The article is assembled in a can typically by using mortar in the joint between the can and the article and positioned in the can to achieve the correct final dimensions of the article. The canned article may then be dried again. This process of fo ⁇ rjing a canned refractory article is very expensive as it requires high temperature firing to form the ceramic bonds and a separate canning process.
• Another method for forming canned refractory articles comprises mixing a refractory aggregate with a chemical binder to form a refractory composition of pressing consistency.
• the composition is pressed to shape the article.
• the article is sized and then dried or cured to form chemical bonds.
• the article is assembled in a can typically by using mortar in the joint between the can and the article and positioned in the can to achieve the correct final dimensions of the article.
• a further method for forming canned refractory articles comprising mixing a refractory aggregate to form a refractory castable.
• the composition is cast into a can and mold assembly to form the shape of the article and the article is sized.
• the article stays in the mold at ambient temperature until the castable sets.
• the canned article is then removed from the mold and dried at a higher temperature. This process eliminates the high temperature firing and canning steps but the range of compositions which can be used to fo ⁇ n the articles is limited. Further, the production rates are limited by the number of molds and set time of the castable.
• Another method for producing canned refractory articles comprises mixing a refractory aggregate with a chemical binder to form a refractory composition of ramming consistency.
• a can is placed in a mold assembly.
• the refractory composition is rammed into the can and mold to form the shape of the article and the article is sized.
• the canned article is then dried or cured to form the chemical bonds.
• This process in which the refractory composition is rammed into the can and molded to form the article takes a lot of time. Further, the rarnming of the composition into the can and mold to form the article is not able to be done at relatively high pressures.
• FIG. 1 is a cross-section of a press cavity die used in the co-molding process of the present invention.
• FIG. 2 is a cross-section of a nozzle manufactured according to the process of the present invention showing the various elements making up the nozzle.
• FIG. 3 is a cross-section of a slide gate plate manufactured according to the process of the present invention showing the various elements making up the slide gate plate.
• the present invention is directed to a co-molding process for producing co- molded, chemical-bonded, canned refractory articles.
• the process of the present invention comprises mixing a refractory aggregate with a chemical binder to form a refractory composition, placing a metal can into a press cavity die, charging the refractory composition into the metal can and press cavity die, subjecting the refractory composition to high pressures while in the press cavity die to shape and size the refractory article, and drying the refractory article at temperatures sufficient to cure said chemical binder.
• the process of the present invention does not require the costly and problematic firing step as the use of chemical bond eliminates the need for high temperature firing.
• the process of the present invention further eliminates the separate canning and sizing steps of the conventional methods of the prior art as in the present invention the forming, canning, and sizing steps are all accomplished in one step.
• the co-molded, chemical-bonded, canned refractory article of the present invention is prepared by first mixing a refractory aggregate with a chemical binder to fo ⁇ n a pressable refractory composition.
• the refractory aggregate material may be in granular or powder form.
• the size of the refractory aggregate particulate is in the range of about a few microns to about a centimeter in diameter. In a preferred embodiment, the size of the refractory aggregate material panicles is in the range from about -3 mesh to about -325 mesh.
• the amount of refractory aggregate material in the refractory composition of the present invention is from about 85% to about 97% by weight. In another embodiment, the amount of refractory aggregate material is from about 90% to about 98% by weight.
• the refractory aggregate may be comprised of aggregate materials known in this field. These aggregates may include, but are not limited to, alumina, mullite, alumina-silicates, silica, zirconia, alumina-zirconia, zirconia-mullite, magnesia, alumina-magnesia spinel, carbon, graphite, metal powders, antioxidants, and combinations thereof.
• the refractory composition further comprises a chemical binder.
• the chemical binder used in the present invention can be any chemical binder known in the art for forming refractory materials.
• the chemical binder can be an inorganic material, an organic material, or combinations thereof.
• Inorganic materials which can be used as chemical binders are phosphates, silicates, sulfates, cements, alumina hydrates, and combinations thereof.
• Organic materials which can be used as chemical binders are resins, pitch, polyvinyl alcohols, and combinations thereof.
• the preferred organic materials used as chemical binders are resins. These resins include, but are not limited to, resole resins, novolac resins, liquid resins, powder resins, and combinations thereof.
• the refractory composition may further comprise amounts of metallic aluminum, silicon, and magnesium metals, or a combination thereof.
• the refractory composition may also comprise components such as modifiers or fillers, so long as the modifiers and fillers do not appreciably change the characteristics of the nozzle.
• the refractory composition is formed by mixing the refractory aggregate, the chemical binder and the other components by any means shown in the art.
• the refractory aggregate and other components may be preblended for a specified time and then mixed for a time.
• the resin binder can then be added, and the composition further mixed for a specified time.
• a metal can is placed into a press cavity die and the refractory composition is then charged into the metal can and press cavity die. While in the die, the refractory composition is subjected to high pressure to form, shape, and size of the refractory article.
• the pressure applied is preferably between about 3 T/in 2 to about 12 T/in 2 .
• Typical presses used in the process include but are not limited to hydraulic presses, friction or screw presses, toggle presses, and isostatic presses.
• the preferred press is a hydraulic press because pressure and size are easily controlled and production rates are high.
• An example of a press cavity die 10 in the present invention is illustrated in
• the press cavity die 10 is comprised of an opening 11 which is su ⁇ ounded by top pad 12, bottom pad 13, liner 14, and liner holder 15.
• the liner 14 is located on the face of the liner holder 15 nearest the opening 11.
• the bottom pad 13 is comprised of several components.
• a facing pad 16 is located on the side of the bottom pad 13 nearest the liner 14. Adjacent the facing pad 16 is a pad sleeve 17, the pad sleeve 17 having one side which is in contact with the opening 11.
• a center pad 19 is located at the bottom of the bottom pad 13.
• a metal can 20 is inserted into the opening 11 adjacent to the liner 14 or adjacent to the liner 14 and on top of the bottom pad 13.
• the refractory composition is then charged into the opening 11 in the press cavity die and pressed to form, shape, and size the refractory article.
• the press provides several advantages over the process for manufacturing canned refractory articles of the prior art.
• One advantage is that forming the article in the press provides higher pressures for better compaction of the refractory material.
• Another advantage is that forming in the press provides better size and shape control.
• a further advantage is that forming in the press requires less time than the ramming and casting processes.
• the article is removed from the die to be dried. The article is dried at temperatures sufficient to cure the chemical binder but not fire or sinter the nozzle. Typically, the drying is carried out in a proper oven and at a temperature lower than that of firing.
• the refractory articles are dried at a temperature of about 200 °F to about 800 ⁇ F.
• the co-molding process of the present invention produces co-molded, chemical-bonded, canned refractory nozzles as shown in FIG. 2.
• FIG. 2 shows a cross section and general structure of a nozzle 30.
• the nozzle has a hollow chamber 31 centrally located in the core of the nozzle and inner wall 32 forming the chamber 31 and an outer wall 33 forming the nozzle proper.
• the nozzle has an inlet
• the outer wall of the nozzle is surrounded by a metal can 36.
• the nozzle is formed by mixing a refractory aggregate with a chemical binder to form a pressable refractory composition.
• the refractory aggregate contains about
• the refractory aggregate contains about 61% coarse aggregate and about
• the chemical binder is preferably a resin.
• the amount of resin present in the composition is from about 3% by weight to about 15% by weight, preferably from about 6% by weight to about 8% by weight.
• a metal can is placed into a press cavity die and the refractory composition is charged into the metal can and press cavity die.
• the refractory composition is subjected to pressures from about 3 T/in 2 to about 7 T/in 2 to form the shape and size of the nozzle.
• the refractory composition is subjected to pressures from about 4 T/in 2 to about 5 T/in 2 .
• the nozzle is dried at temperatures from about 300 °F to about 700 °F, preferably from about 350 °F to about 450 °F.
• FIG. 3 shows a cross section and general structure of a slide gate plate 40.
• the slide gate plate 40 consists of a flat sliding surface 41 which mates with the flat surface of another plate, a boss 42 on the opposite surface to mate with a nozzle, and a bore 43.
• the plate is designed to fit into the slide gate.
• the upper plate is stationary, and the lower plate is moveable to fully or partially align the bores. Molten steel flow is controlled from full stream to complete shutoff by the degree of alignment or misalignment of the bores.
• the slide gate plate is encased in a metal can 44 except the sliding face surface and the boss.
• the slide gate plate is formed by mixing a refractory aggregate with a chemical binder to form a pressable refractory composition.
• the refractory aggregate contains about 50% to about 80% coarse aggregate and about 20% to about 50% fine aggregate.
• the refractory aggregate contains about 62% coarse aggregate and about 38% fine aggregate.
• the chemical binder is preferably a resin.
• the amount of resin present in the composition is from about 2% by weight to about 10% by weight, preferably from about 4% by weight to about 6% by weight.
• a metal can is placed into a press cavity die and the refractory composition is charged into the metal can and press cavity die.
• the refractory composition is subjected to pressures from about 5 T/in 2 to about 12 T/in 2 to fo ⁇ n the shape and size of the plate.
• the refractory composition is subjected to pressures from about 7 T/in 2 to about 10 T/in 2 .
• the plate is dried at temperatures from about 300 °F to about 700 °F, preferably from about 350 °F to about 550 ⁇ F.
• the co-molding process for producing co-molded, chemical-bonded, canned refractory articles of the present invention eliminates the firing or sintering steps required by the prior art processes for producing refractory shapes.
• the firing step requires large amounts of energy that in the process of the present invention can be supplied by the final working environment.
• the co-molded process of the present invention eliminates the separate forming, canning, and sizing steps of the processes of the prior art as in the process of the present invention, the forming, canning, and sizing steps are all accomplished in one step.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• General Engineering & Computer Science (AREA)
• Press-Shaping Or Shaping Using Conveyers (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (4)

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• 1996
  • 1996-05-16 EP EP96920223A patent/EP0963537A1/de not_active Withdrawn
  • 1996-05-16 AU AU58598/96A patent/AU5859896A/en not_active Abandoned
  • 1996-05-16 WO PCT/US1996/006976 patent/WO1997043590A1/en not_active Ceased
  • 1996-05-16 JP JP09540817A patent/JP2000509340A/ja active Pending

Non-Patent Citations (1)

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