US3374594A - Refractory brick for use in suspended roofs - Google Patents

Description

March 26, 1968 c. A. TATE 3,374,594

REFRACTORY BRICK FOR USE IN SUSPENDED ROOFS Filed Jan. 30, 1964 I /2 I ll //v VEA/ 70 Hg. 5 CARL A. 7:475

United States Patent 3,374,594 REFRACTORY BRICK FOR USE IN SUSPENDED ROOFS Carl A. Tate, Pittsburgh, Pa., assignor to Harbison-Walker Refractories Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Jan. 30, 1964, Ser. No. 341,450 2 Claims. (Cl. 52-598) This invention relates to blocks or brick from which suspended refractory roofs for furnaces and the like are formed, and more particularly to composite blocks formed from basic refractory shapes and sheet metal.

Suspended refractory roofs, for example the open hearth roof, frequently are formed from basic brick which are individually supported from their upper ends by metal hangers. Between the individual brick are plates of metal, usually mounted on the brick themselves. When the furnace is heated, the metal plates increase in thickness to tighten the roof and form a monolith-like structure. The advantages of such a construction are well known and are disclosed in several patents. See, for example, the US. patent to Rochow, No. 2,465,170, entitled, Metalcased Composite Suspended Roof Unit; Mason et al., US. Patent No. 2,846,963, entitled, Reinforcing Insert for Furnace Block; Myers et al., US. Patent No. 2,961,805, entilted, Encased Refractory Brick; and Heuer, US. Patent No. 2,652,793, entitled, Refractory Furnace Roof Brick Resistant to Spelling.

A common form of hanger device for suspending these metal encased basic refractory blocks or brick is comparable in design to an inverted T. With this invented T hanger device, a block is suspended from each side of the crossbar. Opposed adjacent faces of such a pair of blocks are physically in face-to-face contact.

Particularly with the newer developments in open hearth roof construction, in which the entire roof is mounted in rigid assembly, with almost no allowance for expansion and contraction, it has become evident to me that the abutting faces of a given pair of blocks or brick suspended from one of the inverted T-shaped hangers should precisely match. There should be substantially no overhang evident when a given pair of brick are mounted.

Many forms of refractory brick construction have been suggested to accommodate the T-shaped or like hanger. A few are noted above. Another one is disclosed in US. Patent No. 2,517,876, to Heuer entitled Refractory Brick for Use in Suspended Furnace Roofs. This Heuer patent discloses use of an inverted U-shaped device arranged to be comolded with a brick.

As those skilled in the art of refractory brick manufacture realize, uniformity of brick dimension must be carefully controlled. Such control is not particularly easy. Substantially equal weight quantities of brickmaking material must be fed to the press if one wishes to obtain a group of brick of uniform dimensions and physical properties. Also, there must be substantially uniform forming pressure exerted to make each brick. Of course, when I refer to physical properties herein, I mean to include such things as density, porosity, thermal conductivity, modulus of rupture and so forth.

It is my opinion that prior practices of providing means in a refractory brick or block by which the brick or block is to be suspended, have tended to be at cross purposes to the desired substantial uniformity of brick dimension and physical properties. Most of the prior methods have called for comolding of a shape and some manner of metal hanger element to form a composite structure. Such comolding procedures, my opinion, tend to cause nonuniform densification of a brick adjacent the cold face. Very often the metal insert is deformed to such an extent the brick cannot be used. Further, with minor variation in 3,374,594 Patented Mar. 26, 1968 pressing pressure and in quantity of charge to the press, the relative positioning of these metal devices from brick to brick is almost an uncontrollable factor. I realize means could be devised to assure substantially uniform positioning of these metal devices from brick to brick even though they are comolded. However, such arrangements would undesirably increase the cost of manufacture. According to this invention, I provide a novel method of fabricating a composite refractory brick for use in suspended roofs which is very easily practiced, requires no expensive tools or press modifications, and reduces the overall raw materials cost as compared to prior methods.

It is another object of this invention to provide a novel composite refractory shape suitable for use in fabricating suspended furnace roofs.

Briefly, according to one embodiment of this invention a composite refractory shape is provided which consists of a generally rectangular, chemically bonded, basic refractory brick that is metal encased and preferably'has internal reinforcing plates. This much is common to the art as shown, for example, in many of the patents above identified. Adjacent the end of the brick which is to serve as the cold end (ie. the end of the brick farthest removed from the metallurgical process high temperatures) a polarized notch or cut-out is formed. This notch is formed during the pressing of the brick. It is made, for example, by a protuberance on the top pressure plate of a brick press so the polarized notch is formed during pressing of the shape. A tubular metal device of complementary polarization is cemented in the notch. Of course, the insert can be friction fitted if desired. Since the same upper plate is used to fabricate each brick, each brick has its suspending structure in precisely the same position. Further, because the pressure plate is machined from quality steal, it is possible to accurately duplicate a series of top pressure plates and notch forming protuberances.

, A better understanding and other objects and advantages of this brick construction will become readily apparent to those skilled in the art from a study of the following detailed description together with the referenced drawings.

In the drawings:

FIG. 1 is a schematic view with some parts broken away to better show the internal arrangement of parts of brick construction according to this invention;

FIG. 2 is an enlarged fragmentary schematic view of the upper end of the brick of FIG. 1 and the tubular insert immediately prior to assembly;

FIGS. 3 and 4 are alternative insert constructions; and

FIG. 5 is a schematic view of a top pressure plate which can be used to make the bricks of FIGS. 1 and 2.

Before describing the drawings in detail, it should be understood they are but exemplary of the best modes now known to me for the practice of my invention and should not be considered limiting. Rather, the spirit and scope of this invention is as defined in the hereafter appended claims.

Most basic open hearth roof brick are basic in character. That is, they are fabricated of materials, for example, selected from the group dead burned magnesia, chrome ore, dead burned dolomite, and so forth. Commerically available ones which are often used are brick made entirely of chrome ore, ones made entirely of magnesia, ones made of a mixture of chrome ore and magnesia in which the chrome ore constitutes from 50 to by weight, of the total brick, which brick are termed chrome ore-magnesia brick, and brick made from a mixture of magnesia and chrome ore in which the magnesia predominates and constitutes on the order of 50, and more usually 60 to 80%, of the total brick. These later brick are termed magnesia-chrome ore" brick.

As is understood by refractory technologists, brick made on a brick press are formed from a semi-dry, size graded, granular material. The granular material is so size graded as to provide good packing when subjected to the action of the brick press to thereby obtain selfsustaining, handleable shapes. Size grading may be, for example, about 30%, by weight, 3+10 mesh, about 20% 10+65, the rest passing a 65 mesh screen. This latter 65 mesh batch component is sometimes referred to as ball mill fines in the refractory brickmaking aft. Ball mill fines usually have from 40 to 60% held on a 325 mesh screen. 'I hese sizings are all Tyler series. This size graded granular brickmaking material is usually tempered with a minor amount of a fluid, for example, 4 or 5% of water, a water-lignin liquor mixture, water and dextrine, cornstarch, etc. Thus, fabrication of refractory brick on a brick press is quite a different art from treatment of very fine powders such 'as are used for the production of electrical porcelains, cutting tools and the like; and while related, is, of course, quite distinct from the art of making shapes from wet or plastic mixtures such as 'are used to make ordinary red clay building brick, concrete blocks, etc.

A composite unit of this invention is comprised of an unburned or chemically bonded basic refractory block -11 having a polarized notch 12 formed in an upper edge thereof, which edge is formed by the intersection of the upper or intended cold end of the brick and one of the larger side faces. A two-piece overlapping metalcase construction is carried on the block or brick 11. I prefer that this case be installed according to the teachings of the US. patent to Cotfman et al., No. 2,736,187 entitled, Composite Furnace Block. Of course, other arrangements can be used such as, for example, gluing the case to the brick, by punching ears through the case and into the brick body, etc. Further, while I prefer a metal sheath about the four long sides of the refractory shape, a single U-shaped metalcase is satisfactory for some uses. Alternatively, one U-shaped case can be used for three sides and a separate, flat plate can be applied to the fourth side.

The brick 11 can include a pair of internal metal reinforcing plates 13 installed, for example, in the manner taught in US. Patent No. 3,082,503, of Myers et al., entitled, Method of Comolding a Metal Insert in a Brick. It should be understood such plates are not necessary. In fact, I believe, in some instances, it is desirable to omit them in order to obtain still better dimensional accuracy and uniformity of densification in the brick.

The notch 12, which is formed in the upper edge of the brick 11, generally can be characterized as having a truncated triangular cross section. Adhesively mounted by cement 14a in that notch is a tubular insert 14 of complementary shape.

A particularly desirable aspect of tubular inserts, such as, the insert 14, is that they may be made by cutting lengths from an extruded tube having substantially uniform cross sectional dimensions from one end to the other. They may be drawn from roundtubing. The inserts 14 are easily inserted in the preformed notch 12. Since the notch 12 and the insert 14 are of very precise dimensions, the resulting composite shape is substantially identical to other shapes made of inserts cut from the same tube and made on the same press (or other presses having an identical protuberance formed on one of the pressure plates).

FIG. 5 shows a pressure plate with the protuberance 21 as an integral part thereof. If desired, the plate and protuberance combination can be cast and then machined to dimension or the protuberance 21 can be formed from a separate piece of stock which is subsequently welded to the plate 21. Of course, the resultmg welded combination would be mac ined t assure dimensional accuracy.

While I prefer the truncated triangular configuration as shown in FIGS. 1 and 2, other polarized shapes may be used. For example, shapes 30 and 31 shown in FIGS. 3 and 4.

I prefer that the notch 12 be formed through an edge. It is easier to maintain dimensional accuracy. However, the polarized notch can be formed through a side surface of the brick a short distance below the intended cold face of the brick. However, I do not suggest this as the most satisfactory manner of accomplishing a composite brick construction according to this invention. One reason is because the resulting wall or thicknes of brick between the cold end and the notch is susceptible to breakage and cracking.

I prefer that the portion of the outer metal casin which covers the side face through which the polarized notch is formed, be itself notched or cut as, for example, thenotch 22 on the case 23 in FIG. 1. Such an arrangement assures maximum coverage of the face of the brick through which the notch is formed. Of course, if one desires, a short plate can be used which terminates just below the notch 12.

The preferred embodiment of this invention is the arrangement shown in FIG. 1, and the brick is of the magnesia-chrome ore type. Preferably the brick contains between 60 and dead burned magnesite of the type disclosed and claimed in US. Patent 3,060,000, of Snyder et al., entitled, Production of Dead Burned Magnesia. The remainder of the brick is refractory grade chrome ore; I prefer Philippine chrome ore. The sizing of the ingredients is substantially, as set forth above, referring to typical size grading for this type of brick. In a 9 by 4% by 3 inch brick, the notch and the complementary insert can be about 2 inches in height, about 3 inches in width at the widest point and about 2 inches in depth.

Having thus described the invention in detail and with sufficient particularity as to enable those skilled in the art to practice it, what is desired to have protected by letters patent is set forth in the following claims.

I claim:

1. A composite refractory shape comprised of a refractory body having opposed ends and sides extending between the ends, an aperture formed through an intersecting side and end said aperture having a base and sidewalls which converge to form a narrow aperture at one of the ends of said body, a tubular oxidizable metal insert of cross-sectional configuration mating the crosssection of said aperture, said insert fixed in said aperture and filling the cross-section thereof, said insert being fixed against upward and downward movement perpendicular to the ends of said body, the said metal insert having at least one planar outer face which is substantially coplanar with the remainder of the end of the shape through which the aperture is formed.

2. The shape of claim 1 in which said insert is adhesively mounted in the aperture.

References Cited UNITED STATES PATENTS 2,930,601 3/1960 Hever llO99 3,204,586 9/1965 Marsh -99 3,086,327 4/ 1963 Samuel et a1. 52270 3,234,703 2/1966 Sullivan 52596 3,292,333 12/ 1966 Sandmeyer et a1. 52--509 FOREIGN PATENTS 927,632 5/1963 Great Britain. 865,537 3/1941 France. 1,278,173 10/ 1961 France.

FRANK L. ABBOTT, Primary Examiner.

JAMES L. RIDGILL, JR., Examiner.

Claims (1)

1. A COMPOSITE REFRACTORY SHAPE COMPRISED OF A REFRACTORY BODY HAVING OPPOSED ENDS AND SIDES EXTENDING BETWEEN THE ENDS, AN APERTURE FORMED THROUGH AN INTERSECTING SIDE AN END SAID APERTURE HAVING A BASE AND SIDEWALLS WHICH CONVERGE TO FORM A NARROW APERTURE AT ONE OF THE ENDS OF SAID BODY, A TUBULAR OXIDIZABLE METAL INSERT OF CROSS-SECTIONAL CONFIGURATION MATING THE CROSSSECTION OF SAID APERTURE, SAID INSERT FIXED IN SAID APERTURE AND FILLING THE CROSS-SECTION THEREOF, SAID INSERT BEING FIXED AGAINST UPWARD AND DOWNWARD MOVEMENT PERPENDICULAR TO THE ENDS OF SAID BODY, THE SAID METAL INSERT HAVING AT LEAST ONE PLANAR OUTER FACE WHICH IS SUBSTANTIALLY COPLANAR WITH THE REMAINDER OF THE END OF THE SHAPE THROUGH WHICH THE APERTURE IS FORMED.

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