US3324811A

US3324811A - Metal encased refractory

Info

Publication number: US3324811A
Application number: US485879A
Authority: US
Inventors: Thomas W Lloyd
Original assignee: Harbison Walker Refractories Co
Current assignee: Harbison Walker Refractories Co
Priority date: 1965-09-08
Filing date: 1965-09-08
Publication date: 1967-06-13
Anticipated expiration: 1984-06-13
Also published as: GB1101869A

Description

June 13, 1967 T. w. LLOYD 3,324,811

METAL ENCASED REFRACTORY Filed Sept. 8, 1965 Fig. 3

INVENTOR. THOMAS w. LLOYD ATTORNEY United States Patent 3,324,811 METAL ENCASED REFRACTORY Thomas W. Lloyd, Glen Burnie, Md., assignor to Harbison-Walker Refractories Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 8, 1965, Ser. No. 485,879 4 Claims. (Cl. 110-99) ABSTRACT OF TI-E DISCLOSURE A composite metal-encased refractory encased in two sheets of bent metal of different thicknesses. Each bent shape is of generally U-shape in which the web portion is relatively narrow and placed over the narrower side faces of the encased brick.

Metal casing for various types of basic refractory brick, both burned and unburned, has long been known as desirable to, among other things, obtain a monolithic hot face when the furnace is placed on line. Basic refractory most usually covers chrome ore brick, magnesia brick, and brick made of mixtures thereof. It additionally covers such materials as olivine, forsterite, dolomite, lime and so forth, alone, in mixture with each other and/ or additionally in mixture with magnesia and/ or chrome ore.

There are many types of open hearth roof construction including sprung arch, flat, hold-up hold-down, etc. Details of these and other constructions will be found in Modern Refractory Practice, 4th edition, published in 1961 by the Harbison-Walker Refractories Company, which details are hereby incorporated by reference.

It is known that refractory brick, with or without metal cases, and roofs made therefrom, expand upon heating. Many and varied have been the expansion compensating suggestions. Among them have been spring loaded skew backs, combustible materials such as cardboard attached to brick faces, compressible materials such as asbestos attached to brick faces or inserted between adjacent brick. Additionally, compressible corrugated metal sheets, or the like, have been inserted between brick, and compressible expansion compensating crimps or protuberances have been formed from the metal which encases the brick. However, in roofs of the low pressure type in which almost no thrust is present across the arch, these prior arrangements have not been altogether satisfactory (usually all the brick in such a roof are suspended rather than using a rib and a valley arrangement). One has not been able to predict expansion as accurately as desired. Looseness across an arch due to miscalculated expansion allowance can cause difiiculties. It thus is considered an object of this invention to provide metal encased refractory particularly suited for low pressure roofs in which expansion is more accurately predictable.

Briefly, the present invention will be described as relates to a standard 9" straight. A 9" straight is the normal standard of the refractories industry and is a brick which is nominally 9 x 4 /2 x 3". It should be understood, however, that the invention is not limited to this specific brick size. According to this invention, such a brick is encapsulated about its four side faces with two overlapping, preformed sheet metal pieces. The outer of the two preformed pieces is of regular U-shaped configuration. The web of the U is considerably deeper than wide. In a preferred embodiment, this first case piece is formed of 22 gauge steel.

A second case piece is preferably formed of 16 gauge steel. Viewed from an end, it also is generally U-shaped in cross sectional configuration. However, instead of two unidirectionally extending integral arms interconnected 3,324,811 Patented June 13, 1967 by a short web, there is provided along one edge of the web a plurality (preferably three) very short tabs or arms. From the other edge of the web extends a single, integral plate section substantially equal in length to one of the side faces of a brick to be cased. This latter section includes an extending edge section which is apertured to serve as means by which a cased brick can be suspended. When the two case sections are overlapped about a brick, they are attached to each other as by welding. The resulting construction will be better understood by reference to the drawings. In these drawings:

FIG. 1 is a perspective view of a metal encased refractory brick according to this invention;

FIG. 2 is a plan view of a blank from which one of the case sections is formed; and

FIG. 3 is a plan view of the other case section.

I believe one reason expansion has not been as predictable as might be desired with previous casing methods is because of the manner in which the cases are associated with the brick. As might be expected, the preferred manner in which to form case sections has been to provide a wide web with short side arms since such a configuration is more easily bent or formed in a die. \Nhen two of such cases are put about a brick, there has been some looseness where two case arms overlap over the smaller brick side faces. It has been easy to install a tight and contiguous sheet over the wide brick faces simply by exerting pressure while the overlapping side arms were welded or subjected to some other means of integrating the case sections and the brick.

In loose roof construction, it has been found that expansion longitudinal of the roof, in which brick are laid with their wide edges parallel with the arch of the roof (as shown, for example, on page 425 of the book Modern Refractory Practice, cited above), is not as critical as expansion through the arch. Thus, I first thought to modify prior casing methods to simply have two deep cases in which the overlapping portions of the cases covered the width, i.e. 9 x 4" faces, in the case of a 9" straight. However, forming such deep cases proved extremely difficult because of the thickness of the metal which had to be used. And it is necessary to have a certain minimum quantity of metal over side surfaces of the brick so simply going to thinner sheets was not the solution. I therefore decided on a combination of sheet thicknesses using a relatively thin sheet for an outer case and a relatively heavy sheet for an inner case, which inner case had a novel configuration. Referring to the drawings, brick according to my invention include a refractory block or brick 10 encapsulated within an inner case section 11 and an outer case section 12. The inner case section 11 is of relatively heavy 16 gauge steel and the outer one of relatively lighter 22 gauge steel. The inner case section 11 is made from a sheet metal blank of the type shown in FIG. 2 and is comprised of a relatively narrow web 15 having a relatively wide first arm 16 depending from one long edge and a plurality of short tabs 17 extending from the opposed edge. In length, the tabs 17 are shorter than the width of web 15. Preferably, their length is less than about half the width of the web, whereas the side piece or arm 16 is considerably wider than the web 15. For example, at least a third again as wide. roughly, when one considers the 9" straight.

The case piece or arm 16 has an extending tab 18 apertured at 19 to form a hanger tab. The aperture 19 is pressed out of the arm 18 to form a finger 20 which is contiguous to the plane of the cold end of the brick 10 (see FIG. 1). This serves to better hold the cases on the brick and prevent them slipping off. Welds 18 affix the arms or tabs 17 to one of the longer arms of the case 12. Similar welds afiix the case sections and the opposed brick face.

To more positively hold the cases and brick together, one of the wider faces of the brick has a plurality of depressions complementary in size and number to the tabs 17, which tabs then are recessed in the brick body and in combination with the arm 20 of the tab 18 assure unit integrity. If desired, ears can be pressed through the brick case into the brick body to further hold the cases on the brick.

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 metal-encased basic refractory block comprised of a generally rectangular refractory shape defined by a hot face and a cold face and four side faces extending between said hot face and said cold face, two of said sides being of substantially equal size and smaller than the other two larger sides of the generally rectangular shape, there being oxidizable metal casing about said side faces extending substantially from the hot face to the cold face, said casing comprised of two overlapping case sections, a first of said case sections being the inner section and comprised of a relatively narrow web, there being an integral sheet metal arm extending from one edge of said web and being wider than said web, there being a plurality of short tabs extending from the other edge of said web, a second case section, said second case section being of metal substantially thinner than that used for the first case section and being comprised of a generally U-shaped piece including a web from which unidirectionally extends two arms, the arms being of substantially equal width, which width is substantially larger than the width of the web, the width of the web of both the inner and the outer case sections being substantially equal to each other and also substantially equal in width to the width of the opposed smaller side surfaces of the generally rectangular shape and a single thickness of metal casing in the form of said web being tight and contiguous to a smaller side surface it overlies, and the width of both arms of the outer case and the integral sheet metal arm of the inner case being substantially equal in width to the width of opposed larger faces of said generally rectangular shape, said tabs seated in complementary depressions formed in the face of the shape over which they lie, there being depressions in a face of said shape complementary in number and size to said tabs, there being means interconnecting the tabs to an overlapping arm of the outer case and additional means fastening the other arm of the outer case to the arm of the inner case it overlies, there being hanger means extending from the cold face of the shape.

2. The composite shape of claim 1 in which the tabs of said first case section are shorter than the web is wide.

3. The composite shape of claim 1 in which said hanger means is integral with the sheet metal arm of the inner case.

4. The composite shape of claim 3 in which the hanger means includes means arranged to cooperate in gripping relation with the cold face and said tabs to hold the case sections and brick together.

References Cited UNITED STATES PATENTS 2,736,187 2/1956 Coffman et al 52599 2,787,345 4/1957 Soubier et al. 52599 X 2,932,265 4/1960 Heuer -99 3,089,284 5/1963 Heuer 110-99 X 3,192,672 7/1965 Heuer 110-99 X FREDERICK KETTERER, Primary Examiner.