Furnace bottom supports

Aug. 26, 1958 f. j. boron 2,849,219

FURNACE BOTTOM SUPPORTS

Filed Dec. 19, 1955 2 Sheets-Sheet 1

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Aug. 26, 1958 f. j. boron 2,849,219

FURNACE BOTTOM SUPPORTS

Filed Dec. 19, 1955 2 Sheets-Sheet 2

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Fran/C -Rβοτοη '•Atterneys

United States Patent Office

2,849,219

Patented Aug. 26, 1958 to be used in a heat treating furnace such as the kind illustrated in U. S. Patent No. 2,686,665, so that the furnace bottom support 10 comprises a work-container support defined in part in the present instance by an upper wall or flange afforded by complemental 180° half-circle wall segments 12A and 12B corresponding to the respective half castings 10A and 10B. It will be observed in Fig. 1 that the fully complemented upper wall thus afforded defines an opening 15 of relatively large diameter, but of somewhat smaller diameter than the bottom of the work-container or basket that is adapted to be supported by the complemental upper wall segments 12A and 12B.

Spaced from the upper wall of the bottom support 10 is an annular or full-circle lower wall defined by complemental 180° half circle wall segments 18A and 18B. The wall segments 12A, ISA and 12B, 18B are integrally united by corresponding half-circle vertical web sections 20A and 20B so as to provide a chamber for gases below the work-container.

The lower wall afforded by the wall segments 18A and 18B extends radially inwardly of the opening 15 in the upper wall, and the rounded inner edges thereof form a lower wall opening 23 which is of substantially less diameter than the diameter of a fan that is adapted to be mounted below the lower wall. Preferably, reinforcing ribs . 25 are cast integral with the half castings so as to extend between the respective upper and lower wall segments as .shown in Fig. 2.

In the furnace, a fan is arranged below the bottom support 10 with the shaft thereof directed upwardly so that the fan blades rotate in a horizontal path beneath the lower wall segments ISA and 18B. The fan thus rotates within a housing or chamber afforded by four helically disposed vanes as 26, there being two such vanes dependent from the respective half castings 10A and 10B in regular circumferential spacing. The vanes are cast integral with the two half castings so as to depend from the respective lower walls 18A and 18B. In this connection, it will be observed that the arrangement of the vanes is such that the inner ends 27, Figs. 1 and 2, terminate at points on the circumference of the opening 15 in the upper wall of the bottom support, and flare outwardly on diverging arcs so that the outer ends 28 thereof are radially outwardly of the respective webs '20A and 20B. The inner ends 27 of the vanes 26 are on a circle that is somewhat larger than the path of the fan blades, and the lower edges 30 of the respective vanes are adapted to serve as standards reposing on the upper face of a base member of the furnace such as illustrated in the aforesaid patent.

It is advantageous to prevent debris or particles of the material undergoing heat treatment from entering the circular fan housing afforded by the vanes 26, and to this end gusset-like guards 33 and 34 are provided so as to extend horizontally between the webs 20A and 20B and the upper edges of the vanes 26 that are outwardly of the webs 20A and 20B as shown particularly in Fig. 1. To assist in centering the work container on the flange or upper wall of the work support 10, vertical lugs 35 are provided outwardly of the webs 20A and 20B. These are preferably located at points where the guards 33 and 34 are joined to the webs 20A and 20B.

As shown in Fig. 1, there is substantial circumferential spacing between the outer edge 28 of one vane and the inner edge 27 of the next adjacent vane, and it will be further observed that the respective ends of the half castings terminate at two such areas, which is to say that the end portion of one half casting extends slightly in a forward direction beyond the outer end 28 of the associated vane 26 while the adjacent end portion of the

2,849,219

FURNACE BOTTOM SUPPORTS 5

Frank J. Boron, Elyria, Ohio, assignor to American Brake Shoe Company, New York, N. Y., a corporation of Delaware

Application December 19,1955, Serial No. 554,075 10

Claims. (Cl. 263—40)

This invention relates to work-container supports for 15 heat treating furnaces of the well known forced convection type.

In many furnaces of the foregoing kind, a fan or such forced draft means is mounted at the bottom of the furnace beneath the basket or work-container carrying the 20 work to be heated, so that the furnace atmosphere is forcibly directed upwardly through and about the workcontainer to heat the work. It has been proposed to dispose between such forced draft means and the workcontainer a so-called bottom support on which the con- ²⁸tainer is rested and which affords a housing in which the forced draft means operates beneath the lower open end of the work-container. Such bottom support has been furnished in the form of a one-piece part, either a unitary casting or segments that are welded to afford a ³⁰full circle bottom support, and .it has been found that these have a relatively short life due to the rather..severe thermal expansions .that ..are encountered.

The primary object of the present invention Is to increase the life of the bottom support of a furnace by ³⁸constructing the bottom ..support of two complemental half castings connected in . such a way . that these complemental parts ..can expand and contract freely, .and .to facilitate this by assuring that certain connecting joints between the half castings do not carry .any of the load ⁴⁰of the work container. Specifically, the .object of .the invention is to provide ears at the opposed ends of the half castings that afford loose joint connections between the half castings so as to unite these while .allowing thermal expansion or creep to occur freely. 45

Other and further objects of the present invention will be apparent from the following description .and claims and are illustrated im the accompanying, drawings which, by way of illustration, show a preferred embodiment of the present invention and the principles .thereof ..and 50 what I now consider to be the best mode in which I have contemplated applying that principle.. Other embodiments of the invention .embodying the same or ..equivalent principles may be used and structural .changes may be made as desired by those skilled in the art with- 55 out departing from the present invention and the .purview of the appended claims.

In the drawings:

Fig. 1 is a top plan view of a furnace bottom support constructed in accordance with the present invention; θθ

Fig. 2 is a .sectional view taken substantially on the line 2—2 of Fig. 1;

Fig. 3 is a top plan view of a half casting; and

Fig. 4 is a side elevation of the half casting shown in

Fig· 3. . _6S

The present invention is illustrated in Fig. -1 as embodied in a furnace bottom support .10 that comprises two complemental half castings IDA and 10B -which at opposite ends are connected together so as to compensate for thermal expansion in a way to be described more γθ specifically hereinbelow.

The bottom support in the present instance is adapted

2,849,319 other half casting extends somewhat rearwardly beyond the inner end 27 of its associated vane 26. The half casting thus having the end portion extended forwardly beyond the outer end of the associated vane is provided with an ear 40 which, as shown particularly in Figs. 2 and 4, is off-set upwardly and then forwardly in a horizontal plane so as to overlap and rest on the flat, free end portion 41, Fig. 2, of the adjacent half casting. Such constitutes an expandable joint, and normally there is slight spacing between the respective ends 43 and 44 of the two half castings as shown in Fig. 1.

To connect loosely the half castings together so that the ears 40 provided on opposed ends of the respective half castings overlap the free end portion as 41 of the adjacent half casting, off set ears are also afforded on the webs 20A and 20B. Thus, as shown particularly in Figs. 1 and 3, ears 46 are off set radially outwardly and then forwardly from ends of the webs 20A and 20B corresponding to the ears 40, and the arrangement is such that these ears 46 overlap the flat, free end portion of the adjacent end of the opposite web 20A or 20B. In the present instance, pairs of fastening bolts as 47 having associated nuts and washers are passed through pairs of aligned openings in each ear 46 and the portion of the web of the opposite half casting that is behind the ear 46. Such openings are indicated at 50 in the ears 46, Figs. 3 and 4 and at 51 at the opposite, flat end of the web 20A, and are slightly larger in diameter than the shank of the bolts so that the half castings are enabled to creep or expand thermally to the full extent as defined by the predetermined spacing between the aforesaid ends 43 and 44 of the half castings.

Of particular importance in the present instance is that the ears 40 are provided at areas where there is circumferential spacing between the adjacent ends of adjacent webs 26 as was mentioned above. This assures that the joint afforded by the ear 40 and the underlying flat end portion of the lower wall segment of the opposite half-casting does not carry any of the load that is carried by the vanes 26 reposing on the support of the bottom of the furnace as was mentioned above. This particular arrangement frees the ears 40 of any vertical thrust so that thermal expansion occurs without resistance.

Hence, while I have illustrated and described the preferred embodiment of my invention, it is to be understood that this is capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.