US3456914A - Inorganic fiber riser sleeves - Google Patents

Description

y 22, 1969 H. E. KQNRAD ETAL 3,456,914

INORGANIC FIBER RISER SLEEVES Filed Oct. 25. 1965 INVENTORS. H QWAKD E Kat/RAD BY SIDNEy SPE gad j y United States Patent 3,456,914 INORGANIC FIBER RISER SLEEVES Howard Edwin Konrad and Sidney Speil, Somerville, N.J., assignors to Johns-Manville Corporation, New York, N.Y., a corporation of New York Filed Oct. 23, 1965, Ser. No. 504,231 Int. Cl. B22d 7/10; C04b 35/68 US. Cl. 249201 14 Claims ABSTRACT OF THE DISCLOSURE Resilient and durable, self-supporting riser sleeve products for metal casting composed primarily of refractory fiber and binder.

This invention relates to riser sleeves for metal casting, and in particular to improved riser sleeves of a novel and advantageous composition and construction.

Riser sleeves, which provide reservoir chambers for molten metal to feed the same back into the mold cavity to compensate for shrinkage during solidification of the cast metal Within the mold, have conventionally been constructed of gypsum plaster or of common exothermic materials. Such materials, however, normally provide constructions which lack resilience and durability, are brittle and thus particularly susceptible to breakage through handling and use. Moreover, the gypsum sleeves are frequently wanting in service, and the exothermic materials employed in the latter type are costly.

It is the primary object of this invention to provide a riser sleeve or construction therefor alfording a low cost product of improved thermal insulating properties and which is highly resilient and resistant to breakage and will effectively endure the high temperatures and aggressive effects of common molten metals and alloys.

It is also a principal object of this invention to provide a riser sleeve which is economical to manufacture and may be formed in any of a wide variety of sizes, dimensions and configurations, is versatile in use in that it can be easily out without special tools or care to alter its configuration or reduce its dimensions and presents a rough exterior surface which efiects better keying or union with the sand mold.

It is a further object of this invention to provide riser sleeves which are compatible with and resist most molten metals and alloys and the temperatures of their melts and which are not wetted or attacked by common molten metals.

It is a still further object of this invention to provide an economical riser sleeve which may be roughly handled under abusive factory conditions without damage or breakage.

These and other objects and advantages of this invention will become more apparent from hereinafter detailed description thereof.

The drawing comprises a pictorial view illustrating a typical cylindrical riser sleeve construction and product formed of the fibrous composition of this invention.

This invention consists of the construction or formation of improved riser sleeves from compositions comprising primarily inorganic fibers and binder, preferably inorganic binder, and the resultant products of such compositions which are self-supporting and of highly effective physical and thermal properties providing a practical, handleable and versatile product for use with typical molten metals and casting techniques and molds therefor. Specifically, the riser sleeves of this invention constitute bodies or units comprising essentially and predominantly an intimate admixture of apt inorganic fibers and inorganic binders Patented July 22, 1969 which may be formed by conventional means and in sub stantially any common or typical configuration appropriate for molten metal risers.

Suitable inorganic fibers for the practice of this invention comprise common manufactured fibers, or synthetically formed as opposed to natural mineral fibers such as asbestos, possessing effective resistance and integrity at temperatures of at least about 1000 F., or more specifically an effective temperature resistance generally in excess of that of the particular molten metal material to be handled. Numerous apt fiber compositions or products together with their effective temperature resistance and other physicals are known in the art and literature, and are available in the market; for example, Product En ineering, Aug. 3, 1964, pages 96 through 100 and Aug. 31, 1964, pages 63 through 66. They typically comprise fibers formed from melts of compositions generally predominantly of silicates of calcium, aluminum and the like dior tri-valent metals, and include the familiar rock wools, mineral or slag wools, glass wools or fibers of high temperature melting conditions, ceramic fibers, and in particular the highly refractive fibers consisting wholly of alumina and silica or primarily of alumina and silica with added oxides such as titania or zirconia, or borosilicate fibers, or essentially pure silica fibers, etc., and assorted apt mixtures of any of the foregoing.

Inorganic binders preferably constitute clays, for example, bentonite or hectorite due to their case of application, I

effective integrating capacity and low cost, among other useful and beneficial properties thereof. However, other inorganic binders may serve either alone or in combination with clay or other given materials; for example, common temperature resistant binders comprise common alkali metal silicate binders of sodium or potassium silicate, borax, phosphoric acid and assorted phosphates or salts as for example aluminum phosphates, colloidal mica, colloidal silica, colloidal alumina such as boehmite, etc.

Also, organic binders such as resins, starch, glues, dextrin, polysaccharide gums, drying oils, rubber, asphalt, which are generally temporary or fugitive in nature in that they decompose and are destroyed at the elevated temperatures of molten metals, are nevertheless effective in uniting the fibrous body and particularly useful in introducing Wet or green Strength into the products. And in combination with high proportions of inorganic fiber, organic binders such as starch alone will provide bodies which will retain their integrity even when in direct contact with many molten :metals during its solidification.

Aside from the essential and predominant high temperature resistant inorganic fibers and binder components referred to above, the compositions of this invention for the formation of riser sleeves may embody ancillary ingredients to, for example, facilitate manufacturing or formation of the sleeves, introduce or modify various properties such as the degree of porosity, bulk or density, and which are compatible with the particular molten metal materials with which the sleeve will be used, and in amounts not suflicient to change the basic and essential characteristics and/or functions of the primary components of the product. For instance, when the riser sleeves are formed by filter molding and ingredients from a dilute aqueous slurry, the most expedient and thus preferred means of manufacturing fibrous riser sleeves or containers of typical configurations, it is desirable to include small quantities of an organic or cellulosic fiber, such as kraft pulp, to facilitate the filter molding and increase the porosity of the product which facilitates removal and dissipation of any vapors formed during pouring of the molten metal and thereby retarding boiling and splattering of the melt. Moreover the products of this invention can normally tolerate minor amounts, for example up to about 50% by weight, of fillers which do not materially affect the properties or function of the essential and viable components or of the product, either for cost reducing or other purposes. For example likely fillers comprise salvage or scrap from either unused or used riser sleeves of this invention, assorted refractory grogs and particles, light weight filler such as expanded perlite, calcined diatomaceous earth, or kyanite, calcined kaolin, alumina, silica, pyrophyllite, etc.

Effective and readily produced riser sleeves of this invention comprise products or constructions composed of inorganic high temperature resistant fibers and binders, either with or without ancillary components, generally within the relative proportions, in approximate percentages by weight of: inorganic fibers40 to 95%; binder-5 to 40%, which preferably comprises 3 to 20% of inorganic binder and up to 20% of organic binder; organic fiber-O to 20%; and filler to 50%. Riser sleeve products of generally overall optimum properties are provided by the preferred ranges of essential and ancillary ingredients, in approximate percentages by weight, of: inorganic fiber45 to 90%; inorganic binder such as bentonite clay-4 to 15%; organic binder such as starch- 3 to 10%; organic fiber such as cellulosic pnlp4 to 15%; and filler-0 to 35%.

The fibrous riser sleeves, or molten metal retainers of this invention can be formed and produced from the above given compositions by means of conventional techniques for shaping and integrating an admixture of fiber and binder into a shape retaining configuration including common means of casting or molding, felting, etc. Preferred techniques contributing to product uniformity and consistency consist of integrating and consolidating a body of the designed shape from a dispersion of the ingredients in an aqueous or the like suspending medium by filter molding. The typical riser sleeve configurations, among others, can be expediently formed by vacuum filter molding with perforated or screened male or female molds defining the configuration and filtering from a dilute water slurry of the fiber and binder, etc., whereby the product may be uniformly shaped and formed by accretion of the constituent solids from the liquid medium passing through the filter mold and thus extended to the required dimensions whereupon the formation is terminated by removal from the aqueous medium and the resulting formed body partially dried by maintaining the vacuum. This technique, in conjunction with the fiber based formulations of this invention, provides bodies which can be promptly removed from the molds while wet and immediately thereafter are handleable and resist breakage through dropping and the like typical abusive factory methods. Other forming means can of course be applied such as simple pan casting or press molding more concentrated slnrries of the ingredients to impart form and remove the liquid medium. However, procedures wherein formation of the product is through gradual and relatively uniform accretion of the components as in filter molding either with or without a vacuum or other actuating means, are preferred as the components are more uniformly united and consolidated into a continuous integrated mass forming the ultimate body.

Referring to the drawing, although the transverse configuration of a riser sleeve product shown as 10 may be of any design, it is usually more expedient both as to their manufacture and use that they be of generally round or cylindrical configuration as illustrated. The preferred riser sleeve products of the fibrous construction of this invention, as shown in the drawing, constitute a cylindrical tube-like body 12 formed of an annular wall 16 provided with an internal cavity 14 passing therethrough. Due to the basically fibrous composition of the annular wall 16 forming the cylindrical tube body 12, the overall structure is highly resilient but of more than ample strength to support itself and contain molten metal within the reservoir chamber formed by the internal cavity 14.

The following examples comprise illustrations of the preferred and typical compositions and formation techniques for the manufacture of the products for this invention and the properties thereof demonstrating the pronounced improvements and advantages of this invention. It is to be understood that the specific proportions or ratios and components of the compositions given in the examples as well as the means, conditions, techniques, etc., set forth therein are primarily exemplary and are not to be construed as limiting this invention to any specific ingredients or proportions thereof and compositions other than those hereinbefore specified as essential.

A number of riser sleeves in a standard product configuration and dimensions of cylindrical sleeves measuring 12 inches in length and of various internal diameters of from 1 to 12 inches in /2-inch increments and standard wall thicknesses of about to /2 inch, were vacuum filter molded on the outside of cylindrical screen core molds provided with internal vacuum, from a dilute aqueous slurry having a solids content of about 0.84% by weight of each of the inorganic fiber and binder, etc., compositions given in the hereinafter examples. Molding was effected by submerging the filter cores into the suspension of ingredients and liquid medium with an internally applied vacuum for a period of about 8 to 16 seconds depending upon the sleeve diameter, then withdrawing the mold and accreted solids forming the sleeve and retaining the vacuum following removal of the sleeve from the slurry for about 10 to 20 seconds, again depending upon the sleeve diameter, to partially dry the product whereupon it may be removed from the mold core. Such products exhibit average dry densities of about 10 to 12 pet. The solid constituents of each dilute aqueous slurry and approximate composition of the formed products were:

The refractory fiber of Examples 1 and 4 consisted essentially of approximately equal parts of alumina and silica, providing an effective temperature resistance in the order of 2300" F. and constituted Johns-Manville Corporations product Cerafelt. The high iron mineral wool fiber of Example 2 was an Eagle Picher Corporation product identified as high iron mineral wool I-ID-2 produced from a lead slag high in .iron and providing an effective temperature resistance of about 1500" F. to 1700 F. The mineral wool of Example 3 was a product formed from metallurgical slags, commercially available from Johns-Manville Corporation as a domestic insulating material under the trademark of Spintone and having a temperature limit of about 1000 F. to 1200 F. In each case the temperature endurance of the riser sleeve products was substantially commensurate with the temperature resistance of the inorganic fiber constituents which constitutes a property available from the vendor or otherwise readily determined and which is generally provided in the art and literature. Thus the inorganic fibrous constituents can be readily selected on the basis of the designed application of the ultimate product.

Riser sleeves produced from each of the compositions of the gven examples were evaluated by filling the same with molten metal. The test sleeves were mounted with their base imbedded in sand and the upper part unsupported and the'metal poured into their interior, permitted to solidify and the casted body resulting therefrom removed whereupon the sleeves were examined and found to be intact. Samples of all compositions of the examples were tested with molten aluminum poured at 15 F. and molten brass poured at 2200" F. The refractory fiber containing products of Examples 1 and 4 performed excellently with both the aluminum and brass whereas the mineral fiber containing compositions of Examples 2 and 3 were very good with alumina but marginal with the molten brass which substantially exceeded their anticipated temperature tolerances. In all cases the molten metals poured quietly with no evidence of boiling or mushrooming and there was no evidence of metal penetration or wetting or chemical attack upon the product. Moreover, it was evident that with careful handling the sleeves could be reused, particularly with aluminum, and provided their evident temperature limits had not been exceeded. The high temperature refractory fiber composition of Examples 1 and 4 in particular appeared unaffected by either the aluminum at 1500 F. or the brass at 2200 F. and it is evident that this version would be reuseable notwithstanding its exposure to temperatures approaching its apparent tolerances.

Further examples of diverse and apt fiber based compositions of this invention suitable for service as riser sleeves for many molten metal casting operations comprise the following given in approximate percentages by weight of the solids, In each of the hereinafter Examples 5 through 7, the refractory fiber is composed of about equal parts by weight of alumina and silica and corresponds to that of Examples 1 and 4.

EXAMPLE 5 Percent Refractory fiber 90 Starch binder EXAMPLE 6 Refractory fiber 95 Acrylic resin 5 EXAMPLE 7 Refractory fiber 70 Bentonite clay l3 Colloidal silica solids 17 (DuPonts Ludox 30% solids) It will be understood that the foregoing details are given for purposes of illustration and not restriction, and that variations Within the spirit of this invention are to be included within the scope of the appended claims.

What we claim is:

1. An improved riser sleeve reservoir retaining chamber for molten metal casting having a self-supporting resilient and thermally durable and insulating hollow body forming the molten metal retaining chamber consisting essentially of inorganic fiber consisting of at least one metal silicate selected from the group consisting of divalent metal silicates and trivalent metal silicates and binder.

2. The improved riser sleeve reservoir retaining chamber for molten metal casting of claim 1, wherein the inorganic fiber consists of at least one metal silicate selected from the group consisting of divalent metal silicates and trivalent metal silicates and the binder comprises clay.

3. An improved riser sleeve reservoir retaining chamber for molten metal casting having a self-supporting resilient and thermally durable hollow body forming the reservoir chamber for the retention of molten metal comprising inorganic fiber and a binder, the said body forming the reservoir chamber for the retention of molten metal being formed of a composition consisting essentially of, in approximate percentages by weight:

Percent Inorganic fiber 45-95 Binder 540 Organic fiber 0-20 Filler 0-35 4. An improved riser sleeve reservoir retaining chamber for molten metal casting having a self-supporting resi-ient and thermally durable hollow body forming the reservoir chamber for the retention of molten metal comprising inorganic fiber and inorganic binder, the said body forming the reservoir chamber for the retention of molten metal being formed of a composition consisting essentially of in approximate percentages by weight:

Percent Inorganic fiber 45-90 Inorganic binder 4-15 Organic fiber 4l5 Organic binder 3-10 Filler 0-35 5. An improved riser sleeve reservoir retaining chamber for molten metal casting having a self-supporting resilient and thermally durable hollow body forming the reservoir chamber for the retention of molten metal comprising inorganic fiber and an inorganic binder, the said body forming the reservoir chamber for the retention of molten metal being formed of a composition consisting essentially of, in approximate percentages by weight:

Percent Inorganic fiber 45-95 Clay binder 3-20 Cellulosic fiber 0-20 Starch binder 020 Filler 0-35 Percent Inorganic fiber 45-90 Clay binder 4-15 Cellulosic fiber 0-15 Starch binder 3-10 Filler 0-35 7. The improved riser sleeve for molten metal casting of claim 6, wherein the inorganic fiber comprises a high temperature resistant refractory fiber composed predominately of alumina and silica.

8. An improved riser sleeve reservoir retaining chamber for molten metal casting having a self-supporting resilient and thermall durable hollow cylindrical body forming a reservoir chamber for the retention of molten metal comprising an annular wall consisting essentially of inorganic fiber consisting of at least one metal silicate selected from the group consisting of divalent metal silicates and trivalent metal silicates and an inorganic binder, the said annular wall being of a compositon comsisting essentially, in approximate percentages by weight, of:

Percent Inorganic fiber 45-95 Inorganic binder -20 Organic fiber 0-20 Organic binder 0-2O Filler 0-35 9. An improved riser sleeve reservoir retaining cham- 12. The improved riser sleeve reservoir retaining chamber for molten metal casting of claim 1, wherein the inorganic fiber is predominately of refractory alumina and silica composition and is present in amount of approximately 45 to-approximately 90% by weight of the riser sleeve and the binder comprises clay.

13. An improved riser sleeve reservoir retaining chamber for molten metal casting having a self-supporting resilient thermally durable, hollow cylindrical body forming the reservoir chamber for the retention of molten metal comprising an annular wall consisting essentially of, in approximate percentages by weight, 45 to 95% of refractory inorganic fiber predominately of alumina and silica, 4 to of bentonite clay, and 3 to 10% of starch binder.

14. An improved riser sleeve reservoir retaining chamber for molten metal casting having a self-supporting resilient thermally durable, hollow cylindrical body forming the reservoir chamber for the retention of molten Percent Inorganic fiber 45-90 Clay binder 4-15 Cellulosic fiber 0-15 Starch binder .3-10 Filler 0-35 10. An improved riser sleeve for molten metal casting 1 having a self-supporting resilient thermally durable hollow body forming the reservoir chamber comprising an annular wallconsisting essentially of inorganic fiber and an inorganic binder, the said annular wall forming the reservoir chamber being of a composition consisting essentially, in approximate percentages by weight, of: 80 to 90% of inorganic refractory fiber predominantly of alumina and silica, 4 to 10% of bentonite clay, 4 to 8% of kraft cellulosic fiber 3 to 7% of starch.

11. An improved riser sleeve for molten metal casting having a self-supporting resilient thermally durable hollow body forming the reservoir chamber comprising an annular wall consisting essentially of inorganic fiber and an inorganic binder, the said annular wall forming the reservoir chamber being of a composition consisting essentially, in approximate percentages by weight of: 45% of inorganic refractory fiber, 4% of bentonite clay, 10%

kraft cellulosic fiber, 6% starch and 35% kyanite.

metal comprising an annular wall consisting essentially of, in approximate percentages by weight, 45 to of refractory inorganic fiber predominately of alumina and silica composition, 4 to 15 of inorganic binder of bentonite clay and colloid silica solids, 3 to 10% of starch binder, 4 to 15% of cellulosic fiber, and kyanite filler in amounts up to 35%.

References Cited UNITED STATES PATENTS 1,989,096 1/1935 Jones 106-38.9 2,366,485 1/1945 Brink et al. 106--38.9 3,173,451 3/1965 Slayter 106-3827 3,072,981 1/1963 Davidson 249201 X 3,262,165 7/1966 Ingham 249197 X 3,321,171 5/1967 Gorka et al. 249201 FOREIGN PATENTS 843,098 8/ 1960 Great Britain, 708,524 4/ 1965 Canada.

J. SPENCER OVERHOLSER, Primary Examiner EUGENE MAR, Assistant Examiner Us. Cl.'X.R. 1os 3s.27, 38.5

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 456 914 Dated July 22 2 1969 Inventor(s) Howard Edwin Konrad and Sidney Speil It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 53, "Simple" should read -simp1y--, Column l, line 71, "gven" should read -given-, Column 6, line 11, "resi-ient" should read resi1ient--, Column 7, line 4, "Inorganic binder 0-20" should read -Inorganic binder 320-,

line 22, "starch binder" should read --starch Column 7,

SIGNED KND SEALED APR 2 81970 {SEAL} Anest:

Edward M. Fletcher, In. R

WIZHLIAM E SGHUYLER, Aucsung Officer Commissioner of Patents

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