US3071500A

US3071500A - Hood-type annealing furnace

Info

Publication number: US3071500A
Application number: US682907A
Authority: US
Inventors: Robert L Corbett; Jr Robert L Corbett
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-09-09
Filing date: 1957-09-09
Publication date: 1963-01-01
Anticipated expiration: 1980-01-01

Description

Jan. 1, 1963 R. L. CORBETT ET AL &07 0

HO0D-TYPE ANNEALING FURNACE Filed se t. 9. 1957 4 sheets-sheet IN V EN TORS Rober# L. (Ea/162#- Jan. l, 1963 R. L. CORBETT ET AL 50 HOOD-TYPE ANNEALING FURNACE Filed Sept. 9, 1957 4 Sheets-Sheet 2 BY/?obe f L. (bI-beft c//c l Jan. 1, 1963 R. L. CORBETT ETAL 9 HOOD-TYPE ANNEALING FURNACE Filed Sept. 9. 1957 4 Sheets-Sheet 5 INVENTORS F/ a. 3. Rebe/f L. Cbrb A ober/ L. Corb e# o Jan. l, 1963 R.'L. CORBETT ETAL L HOOD-TYPE ANNEALING FURNACE Patented Jan. l, 1963 3,071,500 HOOD-TYPE ANNEALING FURNACE Robert L. Corbett, 22664 W. Lake Road, and Robert L. Corbett, Jr., 22732 W. Lake Road, both of Rocky River, Ohio Filed Sept. 9, 1957, Ser. No. 682307 3 Claims. (Ci. 148--13) Our invention relates generally to annealing furnaces and in particular to self-scaling gas tight forced cooler to be used 'with gas tight hood-cover type furnaces for the annealing of heavy charges in the form of strip coils, etc. and more particularly to gas tight, two-part, hoodcover type furnaces to be used with preferably self-scaling gas tight forced coolers for the anuealing of heavy charges in the form of strip coils, etc.

In furnaces of this type, which are generally of the radiant tube fired bell or hood cover type, heat is normally applied to the external side of the cover and then transmitted through an inner sheet metal cover to the coils. Hence, heat is applied in such structures to the coils solely by radiation from the inner cover, except for such heat as may be transferred from the inner cover to other parts of the coils by circulation of the gaseous medium or the protective atmosphere gas within the inner cover. Conversely, in such structures, cooling of the coils, after the charge is annealed, is efected by the dissipation of heat through the inner cover after the furnace is removed therefrom.

With furnaces of this prior art type, a single heating hood or furnace is usually consecutively placed over a plurality of bases with inner covers in succession. Although, such practice represents an improvement over other prior art practices of heating and cooling a charge enclosed in an annealing box in a stationary furnace, considerable expense and time is nevertheless required to raise the temperature of the charge and alternatively to cool the charge to the desired temperature with a resultant high cost of annealing in tons per hour. Hence, in order to reduce the initial and maintenance cost of inner covers and to Shorten the heating and cooling cycles in using such hood-cover type furnaces, many proposals have been made, such as providing various type means for circulating the atmosphere during heating and cooling the charge in inner or protective covers of the type mentioned, providing spacers between stacked coils forming the charge to assist in the absorption of heating through the edges of the coil laps, i.e. aXially instead of radially through successive thicknesses or laps. Corrugated inner covers have further been proposed to increase the radiating surface. Further double wall inner covers have been used in connection with recirculating systems.

` It is therefore an object of our invention to provide means to materially shorten the heating and cooling periods of the annealing cycle.

It is a further object of our invention to provide means whereby economies of time as 'well as expense may be etfected in annealing heavy charges in the form of strip coils, etc.

It is a further object of our invention to provide an annealing furnace which can be used successively with a minimum number of bases and gas tight forced cooling covers, thus increasing the output of annealecl material with a minimum amount of floor space.

Another object of our invention is to provide improved means for self-scaling the gas tight forced cooling covers when these are employed in our invention and placed on the charged bases.

A still further object of our invention is to eliminate purging under inner covers, which is required before placing a furnace over an inner cover with a cold charge.

A further object of our invention is to provide an improved annealing furnace and cooling cover which may be used in the annealing of charges and which will be highly efiicient and economical in use.

Still further objects of our invention and the invention itself will become more readily apparent from a -purview of the description which follows, in which description reference will be made to the accompanying drawings, illustrating a preferred embodiment thereof, in which drawings:

FIG. 1 is a vertical section through a circular twopart hood-cover type furnace disposed upon a granular seal base;

FIG. 2 is a view similar to that of FIG. l showing the cover or upper portion of the two-part furnace of FIG. 1 removed therefrom, the inner liner of the forced cooler being lowered within the lower portion of the two-part furnace of FIG. l for the cooling cycle;

FIG. 3 :is a view showing the furnace of FIG. 1 being removed from the charge covered by the inner liner of the forced cooler;

FIG. 4 is a Vertical sectional view taken through a circular self-scaling gas tight forced cooler with inner and outer granular sealed liners in position with the granular seal base trough associated therewith.

The furnace of our invention, as best illustrated in FIGS. 1 and 2, is of the welhknown type which is removably disposed on a preferably granular seal-type portable base. Such furnace is novelly provided with a removable top 50 in the form illustrated in our invention, or said furnace may :be provided with a hinged top, for purposes later to be described herein.

The hood proper 10 comprises said top St?, a bottom Sea and includes a gas tight structural frame 12 and a ref'actory lining 13. Heating means of any desired type may be mounted in the assembled hood. In the form shown in our invention, radiant tubes 14 extend vertically within the hood and are heated by the combustion of gas supplied.

The portable base 11 includes a gas tight structural fr-ame 15 and a refractory lining or hearth 16 having a cover plate lfia thereon. A charge support plate 17 is carried at suitable elevation above the hearth on radial steel veins 18 and corrugated concentric rings 18a. The support plate 17 has a central opening 41 therein disposed immediately above an opening 41' in the hearth plate 16a. The base 11, as illustrated, is provided with a granular scaling trough 19 to be penetrated by a sealing flange 24 carried by the heating hood. i

In the form of our invention shown in FIG. 1, a recirculating fan motor 22 having a fan shaft 42 and fan blades 43 is positioned immediately below the hearth 16 and centrally thereof and its shaft 42 is: adapted to be projected through the opening 41' in the hearth wherefor its blades may rotate within the central portion of the charge support plate 17 immediately below the opening 41. Atmosphere gases entering through an inlet conduit, indicated at 27, are therefore circulated from below the charge support plate 17 -upwardly through the space betwecn the radiant tubes and the coils 20 stacked coaxially on the support 17, which form the charge to be annealed.

The atmosphere gas is then circulated through coil separators 21 disposed between the adjacent coils 20 and between the bottom coil and the support plate 17 and the orfice plate Zla disposed on top of the charge, then downwardly through the eyes 20b of the coils and the central opening 41 in the charge support plate 17 and thence thlrough the atmosphere gas outlet conduit indicated at By this method of circulation, the atmosphere gas is brought repeatedly into intimate contact with the radiant tubes 14 and the coils 20 which are also subjected to direct radiant heat from the tubes 14, since in this form of our invention no inner cover is used during heating of the charge. Hence the rate of transfer of heat to the charge is appreciably accelerated over that in prior art structures.

If preferred the use of the base fan 22 could be eliminated, wherefor such direct radation from the radiant tubes ;14 to the charge Would be greatly increased, thus aiding in greater production.

After heating the charge, the upper portion of the furnace 50 is removed therefrom. The upper portion 50 may be, as above related, completely removable from the lower portion of the furnace, as in the form shown in our invention in FIG. l where the upper portion 50 is provided preferably with a granular scaling blade 51 and the lower portion 50a is provided With preferably a granular sea1- ing trough 52 into which the sealing blade 51 carried by the upper portion 50 of the furnace is adapted to penetrate when the cover is locked by means of lifting links 53, which may be used to lock the upper portion 50' of the furnace to the lower portion 5011 when the same is in use as above described.

The upper portion, it will be noted, further carries transverse extending guide brackets 54 at various portions about its circumference which are adapted to be disposed over a plurality of guide posts 55 disposed -at a spaced distance about the outer periphery of the base 11, wherefore the furnace may be guided into position and the upper 'portion may be securely seated upon the lower portion when the same are joined.

It will be noted that when the lifting links 53 are disposed in the position indicated by dotted lines, that the said upper cover portion 50 is easily removed from its assembled position with the furnace by lifting same by means of a crane lifting bail 56 secured centrally of the upper portion of said removable cover portion 50. The inner liner 23 of the forced cooler is then lowered through the upper open end of the lower portion of the furnace over the charge, as best shown in FIG. 2, and said inner liner 23, which is a gas-tight cylindrical shell formed of either plain, corrugated or the like steel with granular seal trough 59, is lowered by means 'of the crane hook lifting eye 58 thereof into position. The furnace cover 50 is then again secured to the lower portion 0a of the furnace by lowering the same into seated position therewith and lowering the l-fting links 53 to the position shown Wherefore the assembled furnace is securely locked. The entire furnace is then removed from its association with the charge and forced cooler inner liner 23, as shown in FIG. 3.

The atmosphere inlet connection 2711 is adapted during the lowering of the inner liner 23 to quickly purge the inner *liner while being placed in position over the heated charge as shown in FIG. 2.

Referring now more particularly to 'FIG. 4, the forced ,cooler outer liner 60 is lowered into position over the inner liner after the furnace is removed by means of the crane hook bail 61 to provide gas tight accelerated cooling.

of the charge. This outer shell 29 is preferably provided with a motor driven suction type fan 30 coaxially mounted above a central aperture 29a of its upper portion 29' and is provided with knee braces 31, which serve as members for testing an outer ring of the portable base frame 11. Knee braces 'also serve for supporting the gas tight apron 34 with scaling blades 19' and 59' to penetrate

scaling troughs

19 and 59, thus forming a gas tight seal With inner liner 23 without manual scaling or attention after the extended guide brackets 54' which are adapted to be disposed over guide posts 55 to properly join the forced cooler outer liner 60 with the inner liner granular scaling trough 59. A fan motor frame 35 is secured to the top of the cooler shell 60 as by rivets, bolts 35' or the like and is provided with vents therein to assist in cooling the inner liner 23 adjacent the shell 60. A motor 70 for driving the fan 30 is preferably mounted at one side of the forced cooler 60 adjacent the upper portion thereof and belt means 71 are driven thereby to drive the fan shaft 37.

It will thus be noted that in the annealing furnace of our invention, the heating cycle is considerably Shortened and greater production may be achieved'by the direct heating of the charge due to the elimination of an inner cover. V

Secondly, it will be noted that the inner liner of the forced cooler can be placed over the heated charge with a two-part hood type furnace for protecting the heated charge when removing the furnace and placing the outer liner of the forced cooler into position, thus producing bright annealed coils without the use of an inner cover during the heating cycle.

Third, by providing an inner liner with a granula' sealing trough and the outer liner of the forced cooler with a. gas tight apron having sealing blades to penetrate the inner liner scaling trough and the portable base sealng trough will thus produce bright annealed charges -free from scale `or stains during the cooling cycle.

Fourth, by providing a cooler having fan means associated therewith, the cooling cycle is considerably expedited.

Fifth, by providing the inner liner with a scaling trough, eliminates manual sanding required when using an inner cover during the heating cycle, also any possibilities of occasional sand disturbances in which event -the charge would be discolored requiring re-annealing.

Sixth, improved economics in time will be achieved by the successive use of the two-part furnaces and forced coolers with inner and outer liners and with a minimum number of bases wherefore the output will be increased with a minimum of floor space, time and labor, together with eliminating excessive inner cover maintenance costs.

We are aware that certain improvements may be made in the :form of our invention herein illustrated and described, without however departing from the spirit of our invention or the scope of the rapp'ended cl aims.

*What we claim is:

1. The process of annealing a met-al of a strip coil comprising, in sequential steps, .placirg a hood-type furnace over said charge and heating said charge to an annealing temperature, removing an uppermost portion of said furnace and exposing the strip coil to the atmosphe-re while leaving `a lower portion thereof protecti-vely `surrounding said ch arge, plac-ing :a cooling bell over said change within said lower portion of the furnace, removing said lower portion of said fiurnace, and subsequently allowing said cooling bell to remain in place until said charge has cooled.

2. The process of annealing a metal charge of a strip coi-l compr ising, in sequential steps, placing a hood-type furnace over said change and heating 'said charge to an annealing temperature, removing an upper-most portion of said furnace and ex-posing the strip coil to the atmosphere While leaving a lower portion thereof protectively surrounding said charge, plaoing an unheated cooling cover bell over said charge within said lower portion while concu-rrently purging said cooling bell, removing said lower portion of said furnace, and subsequently al lowing said cooling bell .to remain in place during the References Cited in the file of this patent cooling Of said charge. UNITED STA E PATENTS 3. The process of -annealng a metal charge of a strip T S coil comprising, in sequential steps, placing a hood-type 1268685 Cooudge June 1918 furnace over said charge and directly heating said charge 5 1534319 Ganaghan July 1927 to `an annealing temperature, removing an uppermost 1367737 Hatcher July 1932 portion of said furnace and expos-ing the strip coil to the 2278391 Munford 1942 atmosphere While leaving a lower portion thereof pro- 2781188 MCKOWH 1957 teotively surrounding said charge, placing an unheated 2303449 Ludwlg 1957 cooling bell over said charge within said lower portion of 10 FOREIGN PATENTS the furnace, removing said lower portion of said furnace i without removing said cooling bell, and encompassing x f said cooling bell With a forced air cooler whereby air is rea n am u y caused to pass over the outer surface of said cooling bell to rapidly cool said charge.

Claims

1. THE PROCESS OF ANNEALING A METAL OF A STRIP COIL COMPRISING, IN SEQUENTIAL STEPS, PLACING A HOOD-TYPE FURNACE OVER SAID CHARGE AND HEATING SAID CHARGE TO AN ANNEALING TEMPERATURE, REMOVING AN UPPERMOST PORTION OF SAID FURNACE AND EXPOSING THE STRIP COIL TO THE ATMOSPHERE WHILE LEAVING A LOWER PORTION THEREOF PROTECTIVELY SURROUNDING SAID CHARGE, PLACING A COOLING BELL OVER SAID CHARGE WITHIN SAID LOWER PORTION OF THE FURNACE, REMOVING SAID LOWER PORTION OF SAID FURNACE, AND SUBSEQUENTLY ALLOWING SAID COOLING BELL TO REMAIN IN PLACE UNTIL SAID CHARGE HAS COOLED.