US2878005A - Coil support for box annealing furnace - Google Patents

Description

March 17, 1959 Y K. EGGE 2,878,005

COIL SUPPORT FOR BOX ANNEALING FURNACE Filed Dec. 15, 1955 3 Sheets-Sheet 1 P1E-.- i-

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Mar h 7, 1959 K. EGGE 2,878,005

COIL SUPPORTv FOR BOX ANNEALING FURNACE Filed Dec. 15, 1955 5 Sheets-Sheet 2 hrs-K 3- rm 32 W Wi 1". Q I y t I if:

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his Attorney.

March 17, 1959 K. EGGE 2,878,005

. COIL. SUPPORT FOR BOX ANNEALING FURNACE Filed Dec. 15, 1955 I 1 3 Sheets-Sheet 5 IN VENTOR. KLAUS 5665,

BY. AMA A 5 his Attorney.

United States Patent F 2,878,005 .COIL' SUPPORT FOR BOX ANNEALING FURNACE Klaus Egge 'Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Application December 15, 1955, Serial No. 553,288 11-Clairns. (Cl. 263-47) This invention relates to an improved support for. strip metal coils in a two-high box annealing. furnace.

. The present application is a continuation-in-part of my three earlier applications Serial No. 384,615 filed October7, 1953,.Serial No. 465,277 filed October 28, 1-954, and Serial No. 467,267 filed November 8, 1954, all now abandoned.

Certain types of steel (for example that of high silicon content) require annealing at temperatures exceeding 2000 F. while in the form of coiled strip. 'At such temperatures steel .is mechanically weak, and in a twoehigh furnace the bottom coil cannot sustain the weight of the top coil without becoming damaged. Consequently it is necessary to equip the furnace with a support which carriesthe top coil independently of thebottom coil. in actual practice I have-encountered a further problem in that'most-top coil supports tend to sag at the annealing temperature. If sagging occurs, portions of the top coil telescope downwardly to produce a defective coil. -.I have also observed that the furnace requires internal means for distributing the atmosphere over the coils to anneal them properly.

An object of the present invention is to provide an improved support which carriesthe-weight of a topcoil independently of the bottom coil, prevents telescoping of any portion of the top coil, and also-assists in distributing the furnace atmosphere.

A further object is to provide an--improved support which includes an annular upper hearth plate and cooperating columns supporting this plate at bothits inner and outer circumferences to assure that-it does notsag under the weight of a top coil.

A further object is to provide an improved support which has the foregoingfeatures andin whichthe inner column serves to distribute the furnace atmosphere as-well as-support the upper hearth plate at its inner circumference.

-=A-=further object is totprovide an 'improvedsupport which has'the f'oreg'oingfeaturesand in which the outer column can bemade up of superposed annular" sections to facilitate installation and afford a more stable: structure.

In accomplishing these and other'obj'ects oflthetinvention; I have provided improved details of stmcture preferred forms of which are shown inizthevaccompanying drawings, jirr which:

Figure' 1 is a vertical sectional view' of a boxannealing furnaceequipped with a preferred-form of top coil support constructed in: accordance with my invention;

Figure 2 is ahorizontal se'cti'onon line 1 1-1101; Figure 1;

-Figure= 3 is avertical sectionarsimil'ar tot-Figure 1,. but showing a modified: outer column;

, Figure 4 isa horizontal sectiona on line I-V.:-PV of Figure 3; and

l igure 5 1's another vertical; section-similar tot'Figure 1 but" showing: a: further modified outerc'olumn.

' I Figures- 1,. 31-and 5: show. somewhatudiagrammaticallya portion of a conventional: .box::annealingf furnace which 2,878,005 Patented Mar. 17, 1959 includes an annular refractory pedestal or base 10, a fan 12, and a metal stool 13'. The upper face of the stool carries a plurality of.upstandingribs14'01I'which an annular metal lower hearth plate 15 rests. Anannular metal. upper hearth plate 16 rests on a support constructed in accordance with my invention and hereinafter described. The lower and upper hearth platcs'respectively carry bottom and top coils A and B of strip: metal for annealing. A removable cylindrical inner cover1-7 rests on the pedestal ,10 and can be lifted for charging the furnace. A gas inlet 18 extends upwardly through the pedestal 10 and stool 13 and discharges into the space between said stool and the lower hearth plate 15. The furnace also includes an outer cover and appropriate means for heating the coils to the annealing tempera ture, but not shown since they areconventional.

All three embodiments of my support comprise an inner tubular metal column 19 which rests on a shoulder 20 formed around the inner circumference of-thelower hearth plate 15. This column carries a plurality of rig.- idly affixed radial brackets 21 which are spaced abov'e the height of the bottom coil A and whose upperi faces constitute a ledge. The portion of the upper hearthplate 16 adjacent its inner circumference retst's on this ledge. The inner column contains a plurality of gas circulation openings 22 located between the bottom coil-A and the upper hearth plate 16. This column terminates inter= mediate the height of the upper coil B and its upper end is partially closed to form a restricted orifice 23' of smaller area than the total area-of the openings 22. Thecolumn has an outside diameter of a size to fitnloosely within the central openings of the coils. and leave some clearance; as illustrated.

My support also comprises a cooperating outer. column, the preferred embodiment of which is shown in Figures 1 and 2. This outer column is made upof a plur ality of similar superposed cylindrical sections.24,..24a and 24b, each formed as an integral metal casting. The lowermost section rests on the pedestal; 10 immediately, outside the stool 13. Each section includesan upright'barrehwhich containsga'sscirculation openings 25. The. lower edge of the barrel has a horizontal flange 26 which afiordsra relatively wide supporting. surface. The upper. edge of the'barrel has a horizontal ledge or .flange 27 which: is surrounded by an upstanding rim 28. The upper flange and rim are adapted toreceive the section thereabove, or the uppermost to receive the upper heanth'plate; 16 and thus furnish support thereto adjacent its outer circumference. The inner. and-outer columns are, of course, proportioned so that the brackets 21 of the former and the uppermostflan'ge 27 of the latter are at the; same height. Preferably the outside of the barrel has stiffening ribs. 29. The, outer column has an inside diameter ofa size to fit loosely over the coils A and B andlleavesome clearance as illustrated.

Figures 3 and 4 showa modified construction ofsectional outer column made up of a plurality .ofssimilar superposed cylindrical fabricated metal sections-30, 30a and 30b. The lowermost section again rests on the pedestal 10 outside the stool 13. Each section includes a bottom angle iron ring 31, a plurality of circumferentially spaced uprights 32, and a pair of reversely disposed top. angle iron rings 33 and 34. The uprights; 32 are welded :at their lower ends to theinside of the bottom angle iron 31, and the horizontal leg of the latterthus affords a relatively wide supporting surface. The, uprights 32 are welded at their upper ends to the:.outside ofthe horizontal leg of the top angle iron 33. The .vertic'al-leg of this top angle iron forms an upstandingrim around the column section for receiving thesection thereabove, or the uppermost for-receiving .the upper hearth platev 16- and thus furnishing support thereto adja;

cent its outer circumference. The other top angle iron 34 is placed over the angle iron 33 with its vertical leg extending downwardly inside the uprights 32 to alford increased rigidity. The spaces between the uprights allow gas circulation. Again the column is of a size to fit loosely over the coils.

Figure 5 shows a further modified outer column which is of one-piece fabricated metal construction. This column includes a bottom ring 35, a plurality of circumferentially spaced uprights 36, a pair of intermediate reinforcing or binder rings 37 and 38 and a top ring 39. The uprights 36 are welded at their lower ends to the upper face of the bottom ring 35 and at their upper ends to the underface of the top ring 39. The intermediate rings 37 and 38 encircle the uprights and are welded to the outside faces thereof. The column rests on the pedestal immediately outside the stool 13 and supports the upper hearth plate 16 adjacent its outer circumference, and loosely receives the coils A and B.

'In each embodiment of my invention the inner and outer columns cooperate to support the upper hearth plate 16 at both its inner and outer circumferences independently of the bottom coil A. At the annealing temperature this hearth plate is structurally weak and would sag if supported at only one of its circumferences. The resulting unevenness would allow portions of the top coil B to telescope downwardly and thus produce a defective coil. In each embodiment gas which forms the furnace atmosphere enters the inlet 18 and flows outwardly beneath the lower hearth plate 15. A portion flows over the bottom coil A and into the interior of the inner column 19 via the openings 22. Another portion flows through the openings in the outer column, over the top coil B and into the interior of the inner column 19 via the orifice 23. The fan 12 draws gas downwardly from the inner column and recirculates it outwardly beneath the lower hearth plate. Proper proportioning of the areas of the openings 22 and orifice 23 distributes the circulating .atmosphere between the two coils.

In the embodiments shown in Figures 1 to 4 each section of the outer column is of relatively low height and provides a substantial bearing surface on which the section above can rest. Consequently each section has a low slenderness ratio to resist buckling. Different levels of the furnace may be at different temperatures, and hence thermal expansion of the support may not be uniform. The sectional construction enables different parts of the support to expand independently and thus overcomes any tendency of the support to buckle because of non-uniform expansion. The number of sections of the outer column can vary with the height of the bottom coil A as long as the height of the inner column corresponds.

In the preferred method of charging the furnace, the outer column is positioned and the bottom coil inserted with a crane. Next the inner column is inserted in the central opening of the bottom coil and the upper hearth plate placed on the two columns. Finally the top coil is placed on the upper hearth plate.

While I have shown and described certain preferred embodiments of my invention, it is apparent that other modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

I claim:

1. In a two-high box annealing furnace which includes a base, a lower hearth plate supported on said base and adapted to support a bottom coil, said base and plate having aligned central openings, and a fan positioned below the opening in said plate, the combination therewith of a support for a top coil comprising a cylindrical outer column of greater inside diameter than the outside diameter of said plate, said column resting on said base surrounding said plate and adapted to surround the bottom coil, a tubular inner column open at its lower end 4 resting on said plate in alignment with said openings and adapted to extend through the central opening of the bottom coil, said columns having respective supporting surfaces at the same height above the height of a bottom coil, and an annular upper hearth plate removably resting on the supporting surface of said outer column adjacent its outer circumference and on the supporting surface of the inner column adjacent its inner circumference and adapted to support a top coil, said columns cooperating to provide positive support for said upper hearth plate adjacent both its outer and inner circumferences, thereby preventing the upper hearth plate from sagging under the weight of a coil at annealing temperatures, said outer column having gas circulation openings, said inner column extending above the supporting surface thereon and having gas circulation openings located beneath the supporting surface thereon, the upper end of said inner column being partially closed to form a restricted orifice of smaller area than the area of the circulation openings in the inner column enabling said fan to move gas vertically through said inner column via both the restricted orifice and the circulation openings therein and thus distribute gas between the two coils.

2. A combination as defined in claim 1 in which said fan draws gas downwardly through said inner column.

3. A support as defined in claim 1 in which said outer column is made up of a plurality of superposed sections each having a relatively wide horizontally extending supporting surface at its bottom, a second horizontally extending supporting surface at its top and an upstanding rim surrounding said last named supporting surface and adapted to receive the section thereabove.

4. A support as defined in claim 3 in which each of said sections is formed as an integral casting including a barrel and flanges on the top and bottom thereof.

5. A support as defined in claim 3 in which each of said sections is formed of uprights and top and bottom angle irons welded to said uprights, said uprights being spaced to provide the gas circulation openings in the outer column.

6. A support as defined in claim 1 in which said outer column is of one-piece construction and includes bottom and top rings, a plurality of spaced uprights welded at their respective ends to said rings, and intermediate reinforcing rings welded to said uprights.

7. Apparatus for supporting coils in a box annealing furnace having a base with a center opening therethrough, which aparatus comprises a lower hearth plate having a center opening therethrough supported on said base with its center opening in communication with the center opening in said base and being adapted to support a coil disposed thereon, an inner column having a circumferential supporting ledge ainxed thereon intermediate its ends removably disposed on said lower hearth plate over the center opening therein, said supporting ledge being spaced above said lower hearth plate a distance exceeding the height of a coil, an outer column having an inside diameter greater than the outside diameter of said lower hearth plate and projecting upwardly therefrom surrounding said lower hearth plate, the top of said outer column being in the same horizontal plane as the top of said supporting ledge, and an upper hearth plate having a center opening therethrough disposed on the top of said outer column and said supporting ledge with its center opening fitted around said inner column, said inner column projecting upwardly a distance above said upper hearth plate.

8. Apparatus for supporting coils in a box annealing furnace as defined by claim 7 characterized by said inner and outer columns having a plurality of openings through the walls thereof.

9. Apparatus for supporting coils in a box annealing furnace as defined in claim 7 characterized by said inner column including a tubular member having gas circulation openings beneath said ledge, and means forming a restricted orifice of smaller area the upper end thereof.

10. Apparatus for supporting coils in a box annealing furnace as defined by claim 7 characterized by the periphery of said outer column including a plurality of spaced-apart vertically disposed bars, a ring attached to and spanning the tops and bottoms of said bars, and at least one binder ring attached to and extending concentrically around said outer column.

11. Apparatus for supporting coils in a box annealing furnace as defined in claim 7 characterized by said outer column including a plurality of superposed cylindrical sections.

than said openings at References Cited in the file of this patent UNITED STATES PATENTS Chapin Apr. 19, 1932 Machlet Feb. 16, 1943 Burdette Dec. 6, 1949 Hoop June 26, 1951 FOREIGN PATENTS Great Britain July 7, 1927 Patent No 2,878,005 March 17', 1959 Klaus Egge It is hereby certified that error of the above numbered patent requiring Patent should read as corrected below.

appears in the printed specification correction and that the said Letters Column 4, line 32 claim 3, after thereafoove ancl before the period insert and the uppermost to receive said upper hearth plate we Signed and sealed this 30th day of June 1959a E Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents

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