US1725398A - Metal-treating furnace - Google Patents

Description

Aug. 20, 1929. A, T, KATHNER METAL TREATING FURNACE Filed April 17. 1928 2 Sheets-Sheet l INVENTDR HT TDRNEY EWMWM NN N mN mw m H mlHIlm A. T. KATHNER METAL TREATING FURNACE Aug. 20, 1929. l

Filed April 17, 1928 2 Sheets-Sheet 2 INVENTUR JMW HTTDRNEY nl: I

Patented Aug. 20, 1929.

UNITED STATES PATENT OFFICE.

ARTHUR T. KATHNER, OF NEW CUMBERLND, WEST VIRGINIA.

METAL-TREATING FURNACE.'

Application led April 17,

This invention relates broadly to furnaces for normalizing, heat-treating and/or processing metal sheets and other metal products, and it has for its primary object to provide a continuous furnace of traveling conveyor type of which the top or arch is composed, either in whole or in part of complemental abutting sections which are separately elevatable, removable and interchangeable.

A further object is to provide a continuous furnace of multiple type including a normalizing and heating chamber and a cooling chamber,l said chambers being arranged in alined relation and provided with conveyor mechanism whereon the material under treatment is advanced, said cooling chamber having a length which materially exceeds that of the heating chamber and being designed to afford means for controlling the rate of cooling to the extent that there may be imparted to the mateal practically any desired characteristic o tainable by or through heat treatment. These and other objects of my invention will, however, appear subsequently herein.

This application is a continuation in part of my application, Serial No. 111,754 from which Patent N o. 1,669,902 issued subsequent to the filing of this present application.

In describing the invention in detail, reference isherein had to the accompanying drawings, in which- Figures 1 and 1"L show the invention partly in side elevation and partly in longitudinal section;

Figures 2 and 3 are cross sections taken, respectively, on lines 2 2 and 3 3, Fig. 1; and

I Figure 4 is a similar section on line 4 4,

fig. la.

Referring to said drawings, A designates generally a heating or normalizing furnace which comprises opposite side walls 1 and a plurality of complemental abutting arch sections or units 2 which are superimposed upon said walls. Suitably journaled upon members disposed outside of the said side walls and extending through the latter is a succession of suitably driven, transversely disposed shafts 3 which carry conveyor disks 4 upon which the metal, in the form of sheets,'slabs, bars, or the like, is advanced.

Located in alinement with the heating chamber a of the furnace and communicating with the forward end of the latter is a coolthe annealing or processing desired. Said chamber b has journaled upon its side walls 5 a Isuccession of transverse conve or shafts 6, similar to the `shafts 3 of cli'amber a, which carry conveyor disks 7 upon which the metal under treatment is advanced.

A damper controlled stack 8 is located over the heating chamber at a suitable point, preferably adjacent to one or the other of its ends, through which the products of combustion are permitted to escape at a controlled rate.

Located at the forward end of the heating chamber a is a fire-wall 9 which has its lower end located at a suitably spaced distance from the level of the conveyor so as to provide thereunder an open space or passage 10 which constitutes an avenueof communication between .the said chaniber a and the chamber b. A fire-door orbaflle 11 located adjacent to said re-wall 9 is adjustable vertically relative to the path of travel of the metal borne bythe conveyor disks whereby may be controlled to practically any extent desired the passage of heat from the heating chamber a to the cooling chamber b through said opening 10. f

I The side walls 5 of the cooling chamber b have seated thereon an arch composed of a plurality of complemental relatively abutting umts or sections 12 of suitable dimensions. In the preferred construction, herein shown, the arch sections 12 have their crowns occupying a level materially lowerI than that occupied by the crowns ofthe arch sections 2 of the heating chamber, thereby to confine the products of combustion admitted to the cooling Achamber in relatively close contact with the metal under treatment and to assist in the maintenance Within the cooling chamber of a practically neutralizing atmosphere. Each of the various arch sections 2 and 12 comprises .a metal frame structure which includes transversely disposed structural members 13 having their opposite ends depending in positions to form side members 13 which rest against the outer faces of the parts of its length. In this illustrative construction, the sections 2, which are required to withstand excessively high temperatures,

embody a heavy lining 15 of refractory material, as fire brick, and a heavy outer covering 16 consisting of a suitable heat insulating material, as bricks or blocks of an asbestos composition. Those arch sections 12 of the cooling chamber b which are located more or less directly adjacent to the forward end of the heating chamber a em` body a relatively light lining 17 of refractory brick, or its equivalent, and a light lcovering 1801i heat insulating material, whereas those arch sections of the cooling chamber remote from the heating chamber may be formed with a sheet metal covering 19 and a protective lining 20 of rock wool 1 or asbestos in blanket form.

The metal frame members 13 of the arch sections have formed thereon lifting lugs or-eye portions 21 to which may be readily attached the carrying chains of a lifting crane whereby any such arch sections may be elevated from their seated positions either for the purpose of partially opening the underlying chamber to permit a more rapid dissipation of heat or for bodily removing such sections, as for replacement or to permit access to said chamber for repairs such as removal of the shafts 3 to effect repairs.

to or replacement-of the conveyor disks.

The arch sections are made of such length that, when cold, open joints are provided between adjacent sections. These joints permit of unobstructed expansion of the sections and, when so expanded by heat within the Vunderlying chamber, are sealed withtire clay.

The described sectional arrangementor construction of the furnace has for one of its objects to provide for expansion and contraction of the arches, resulting from the Widely varying temperatures maintained in thechambers, without undue buckling or distortion and without derangement of either the conveyor or the driving mechanism, said sections being more or less free to move upon the side walls by which they are supported. Moreover, when the lining of, any section requires renewal or repair, such sectionl may be removed bodily and a spare section kept for the purpose may immediately be introduced in the place of the removed section without shutting down the furnace,'thereby obviating the long delays which have heretofore been necessitated in cases where repairs, even of minor nature, were required, such delays being greatly prolonged by the usual requirement that `the furnace be allowed to cool oif completely before repairs could be undertaken.

A further important object of the sectional Aarch construction, and the primary object so far as the cooling chamber is concerned, is' to provide means whereby may be controlled the rate of cooling of the metal as it passes through said chamber. As is well understood in the art, the character and quality of the metal product is almost whollyl chamber b, as required. Manifestly, a great variety of results may be arrived at lby elevating or removing different sections of the arch from time to time to vary the rate and duration of cooling of the metal under treatment.

Vent openings 22 are provided in some or all of the arch sections through which heat may be allowed to escape as desired, and which also serve as openings through which a pyrometer may be introduced for taking temperature readings.

Manifestly, the rate of cooling of the product may be additionally controlled by changing the elevation of the bafHe 11, as also by regulation of the speed at which the conveyor disks are driven.

It is to be noted hat the cooling chamber b has the arch. sections thereof overlying the `conveyor disks much more closely than do the corresponding sections of the heating chamber a, the purpose being to hold the excess products of combustion entering the cooling chamber in relatively close Contact with the advancing metal, thereby to preserve a substantially neutralizing atmosphere in the path of travel of the metal.

The cooling chamber b has a length which materially exceeds that of the heating chamber a, it being desirable that the conveyor disks shall operate throughout at a uniform rate of speed andthat the cooling shall be effected at a controllable rate and in time eX- ceeding that'required to effect heating to the maximum required temperature. It has been determined that the rate of the time of cooling to that of heating should in practically every case be somewhat in excess of 4 to 3; that is to say, the cooling of the transported metal should consume not less than four minutes to each three minutes required to effect heating, or, if the conveyor disks 4 and 7 be driven at uniform speed, the cooling chamber shall have a length providing .approximately four feet of cooling travel to each three feet of heating travel in the heating chamber. It will be noted, however, that the distance of such heating travel should be figured from the position of the first of the fuel burners 26 within the heating chamber to the last of said burners, which burner may be located at a distance from 8 to 15 feet from the entrance end of said chamber.

As herein shown, the floor 23 of the heating chamber is formed of refractory material which may have any desired thickness. Such fioor and part of the floor of the cooling chamber overlies a layer 24 of a suitable heat insulating material and -is sealed thereby from excessive heat loss therethrough whereby the rate of dissipation of heat through earth absorption is materially reduced, thus to effect a substantial-conservation of heat, and to permit heat reflection from the floor 23 to the underside of metal pieces carried on the conveyor and thus spaced above the fioor.

Among the practical advantages which ac- 'erue from the employment of the insulated floor structure described may be mentioned that of conserving heat, the insulation preventing the radiation of heat through the hearth or floor structures when the latter occupies positions above the ground level, and preventing the dissipation of heat through earth absorption in cases wherein hearth structures rest upon the ground.

A further highly important result is that, in furnaces of the character to which the invention is applicable, as hereinbefore mentioned, a much more even distribution of heat throughout the furnace chamber is obtained.

In practice with a normalizing furnace in which the hearth or floor is insulated or sealed as described above, the temperature at or adjacent to the center of the heating chamber approximates 1800 degrees Fahrenheit with about 100 degrees Fahrenheit difference between the temperatures at the top and bottom of the furnace chamber. In furnaces of identical construction, except that the floor or hearth is not so insulated, the temperatures often vary as much as from about 150 degrees to about 350 degrees, between the top of the furnace and the floor of the furnace. When the floor is so much cooler than the other parts of the furnace the amount of heat reiiected from the floor to the underside of the metal pieces on the conveyor will be correspondingly diminished and the efficiency of the furnace correspondingly lessened or the expense of properly heating all of the metal pieces on the conveyor somewhat increased. Furthermore, with such wide temperature variations and with metal pieces in sheets or packs on the conveyor the lowermost metal may not be heated to the extent to which the upper pieces are treated and consequently the product obtained will notbe of the desired uniformity.

A further very important advantage in the furnace described herein is that, by reason of the sealing of the hearth or floor from excessive heat loss and dissipation of heat therethrough, the width of the furnace may be very materially increased without any noticeable effect upon the desired quality of the metal pieces heated in such a furnace. In other words, the resulting product has the same desired properties regardless of the width of the furnace. Furthermore, by widening the furnace metal material of a greater width or metal in side by side rows may be passed through the furnace, where in previously constructed furnaces narrow metal pieces had to be used or only one set of wider pieces could be passed through in single ileat a time. The wider furnace results in greatly increasing the tonnage which can be turned out by afurnace, but the fuel consumption is not increased in proportion to the tonnage turned out by the larger furnace. By widening the furnace as this invention makes possible, the labor costs of treating metal are considerably decreased.

The term heat insulating material as employed in this specification and in the claims includes such material as asbestos, infusorial earth, diatomaceous earth and other materials having similar properties of relativelyv low heat penetration characteristics in contrast with such materials as brick work or steel plate which more readily permit the passage of heat therethrough.

Claims to methods which may be practiced in furnaces constructed as herein described are presented in my copending application, for U. S. 'Letters Patent, Serial No. 338,780 filed February 9, 1929.

What is claimed is- 1. A continuous open ended annealing and heat treatingv furnace comprising a heating chamber and a cooling chamber aligned therewith, means providing a continuously open passage communicatiner with and joining said chambers, means for continuously conveying metal to be treated successively through said chambers, and means for continuously passing heated gases through the cooling chamber around the material and out at the exit end of the cooling chamber, said chambers having proportionate lengths affording approximately four feet of cooling zone travel -to each three feet of heating zone travel of the conveyed material.

2. In a continuous furnace of the character described, open ended, aligned, continuously communicating heating and cooling chambers, the cooling chamber being formed in part by anelevatable crown consisting of an arch and side Walls to permit of ready access to conveyor mechanism in the cooling chamber, conveyor means for moving metal to be treated through the heating and cooling chamber, the cooling chamber having a length between about one and about one and a third times that of the heating zone of the heating chamber.

3. A continuous open ended annealing and heat treating furnace comprising aheating chamber, a cooling chamber continuously communicating with the heating chamber, means for passing metal to be treated successively through the heating and cooling chamber, and means for continuously passing heated gases through the cooling chamber around the metal being treated and out at the exit end of the vcooling chamber, said cooling chamber having a length between about one and about one and a third times that of the heating Zone of the heating chamber. Y

Ll. The herein described continuous method of heat treating metal, which resides in creating continuously open ended and communicating heating and cooling zones, the cooling zone being at least equal in length `to that of the heating zone, controlling the amount of heatadmitted to the cooling zone from the heating zone, continuously passing heating gases through the cooling zone about the metal being treated and out through the exit end of the cooling zone, continuously moving the metal being treated through the heating zone and then through the cooling zone, and controlling the time rate and uniformity of cooling of the metal in-the cooling zone.

5. The herein described continuous method of heat treating metal, which resides in creating continuously open ended and communicating heating and cooling zones, the length of the cooling zone being from about one to about one and one-third times that of the heating zone, controlling the amount of heat admitted to the cooling zone from the heating zone, continuously passing heating gases through the cooling zone about the metal being treated and out through the exit end of the cooling zone, continuously moving the metal being treated through the heating zone and then through the cooling zone, and controlling the time rate and uniformity of cooling of the metal in the cooling zone.

6. The herein described continuous method of heat treating metal, which resides in creating continuously open ended and communicating heating and cooling `zones, the. length of the coolingv zone being approximately one and one-third times that of the heating zone, controlling the amount of heat admitted to the cooling zone from the heating zone, continuously passing heating gases through the cooling zoneabout the metal being treated and` out through the exit end of the cooling zone, continuously moving the metal being treated through the heating zone and then through the cooling zone, and controlling the time rate and uniformity of cooling of the metal Ain the cooling zone.

7. A continuous open ended annealingand heat treating furnace of the conveyor type comprising a heating chamber, a cooling chamber arranged in aligned relation therewith and having continuous communication with the heating chamber, and means including a restricted passage between the heating and cooling chambers for passing heated gases from the heating chamber through'the cooling chamber around the metal in the cooling chamber and out at the exit end thereof, said cooling chamber having a length between about one and about one and a third times that of the heating zone of the heating chamber.

8. A furnace for heating metal pieces comprising a heating chamber formed by side Walls, a roof, and a floor, a conveyor on which metal pieces are moved through the chamber while spaced apart from the ioor, fuel firing heating means in the side walls for producing heated products of combustion in the furnace in the presence of metal pieces on the conveyor, and means including heat insulating material underlying and sealing the floor against excessive dissipation of heat therethrough.

9. A furnace for heating metal pieces comprising communicating heating and cooling chambers formed lby side walls, a roof and a floor, a conveyor on which metal pieces are moved through the chambers while spaced apart from the floor, fuel firing heating means in the side Walls of the heating chamber Afor producing heated products of combustion in the furnace in the presence of metal pieces on the conveyor, and means including heat insulating material underlying and sealing the floor of the heating chamber and part of the floor of the cooling chamber against excessive dissipation of heat therethrough.

In testimonywhereof, I affix 'my signature.

ARTHUR T. KATHNER.

DlscjuatlS/IER Y `V1,725,3985flrtih'm T. Katharer, New ,Cumberland Va. METALfTREA'rING' FUaNaoa. c Patent dated August 20, 1929. Disclaimer .iled- June 5, 1931,

by tliepatentee, exclusive licensee, The vDumloy Company, approving. v Hereby does disclaim from the scope -of claim 3 of the said Patent No. 1,725,398, any andI all furnaces except sheet metal treating furnaces in which heat insulating '-materal is employed in a vportion 'of the cooling zone' adjacent to. the heating zone to'retard the dissipation-of vcooling zone. l y .y

Your petitioner' further doesherebydisclai'm from 4the scope of claim,4 of the said Patent No.YV 1,725,398 any and all processes of ,heat treating metal except sheet metal treating processes in which ythe contro-lof the time, rate and uniformity of cooling of the metal'in the cooling zone is accomplished in part by slowly dissipating heat Afrom the entering end of the cooling zone tothe discharging end thereof While eat from the sheet metal and gases in such portion of the Y maintaining narrow temperature variations in any given transverse section of the cooling zone.

Your petitioner hereby further does disclaim from thescope of claims v5 and 6 of the said Patent No. 1,7 25,398 any and all methods of heat treating metal except sheet metal treating methods -in W 1chl the time, rate and uniformity of cooling of the sheet' metal is controlied in-.part by retarding'the dissipation of' heat fromthe .sheet metal for a portion of thelength of the cooling zone adjacent to the heating l ZODB.

Youi` petitioner further hereby does disclaim -from the scope of claim 7 o the said PatentNo. 1,723,398 any andall furnaces except sheet metal treatin .furnaces havmgconveyors Winch' space tll sheet metalapart from the Walls of7 vt e coolingl chamber and employing heat ins` wall or wallsv of a portion of the 'ooling chamber. to retardv dissipation of heat from gases in the portion of the cooling chamber adjacent to the heating. chamber.

` Your petitioner further hereby does disclaim from the scope of claim l9 of the said Patent No.` 41,725,398 any and` all furnaces for heat treating metal except. sheet ating material below the lsheet'metal and/or in a.

metal treating furnaces Which have a restricted passage therein and are adapted to:

I I causea gradual and prolonged cooling of the metal by heated gases passing through the restricted passage, aboutthe metal and out the exit end of the furnace.

[Ojicial Gazette June .93, 1931.]

DISCLAIMERv 1,725,398.-Arthur T. Katlmer, New Cumberland, W. Va. METAn-TREA'IING Fon- NAoE. Patent dated August 29, 1929. Disclaimer filed May 16, 1935, by the patentee, the exclusive llcensee, The Duraloy Company, assenting.

Hereby disclaims from the aforesaid patent claims 3, 4, 5., 7 8 and 9. [omi Gazette, June 4, 1935.1

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