US1858678A - Sheet metal normalizing furnace - Google Patents

Description

E. E. MCVEY ET AL. 1,858,678

Filed Feb. 2s, 1929 z sheetssneet 1 Nrn May 17, 1932.

SHEET METAL NORMALIZING FURNACE Patented May 17, 1932 UNITED 'STATES SELLIER E. MCVEY, OF YOUNGSTO'WN,

PATENT OFFICE SHEET METAL NORMALIZING FURNAC'E Application illed February 23, 1929. Serial No. 341,925.

Our invention relates to that class of furnaces employed foi' normalizing metal sheets or the like by subjecting them tol heat for the purpose of eliminating the effects of the strains and stresses incident to the preceding rolling or other operations, among the principal objects of the invention being to provide a normalizing furnace so constructed as to be capable of normalizing a much greater quantity of material in a given time than the normalizing furnaces heretofore in use and at a materially lower cost per ton of material treated; to provide a normalizing furnace in which `the principles of recuperation and regeneration are employed in such manner as to preheat the incoming cold sheets by heat radiated from the outgoing hot sheets whereby material economy in fuel cost is effected through utilization for the performance of useful work of a large amount of heat which would otherwise be entirely lost, and to provide a normalizing furnace so constructed that the sheets to be normalized may be fed thereinto from opposite ends of the furnace and moved therethrough in opposite directions whichl results, among other things, in substantially doubling the capacity of the furnace without a corresponding increase in its size, this construction also permitting the normalizing in a single normalizing furnace of sheets supplied from separated furnaces, mills or other sources and at a far less fuel cost than would be required for normalizing a like quantity| of sheets in two separate normalizing furnaces of the type usually heretofore employed and respectively located adjacent the separate sources of sheet supply.

Further objects of the invention are the provision of a normalizing furnace embodying means for rapidly reducing the temperature of the sheets passing therethrough after the same have been raised to the temperature required for normalization so as to quickly bring about a practical fixation of the fine grain structure of the metal; to provide a normalizing furnace having a central hot or final temperature zone and a cooling zone adjacent each end thereof and which embodies a system of bailles or equivalent means whereby the heat supplied to the final temperature zone is in large measure confined Y thereto and prevented `from escaping therefrom.

Still further objects of the invention are to provide a normalizing furnace in which accurate temperature regulation may be read- 11y obtained, which is satisfactorily and eiliciently operative for-the performance of its intended function, and in which, in that embodiment thereof which is generally preferred, the heat for normalizing the sheets 1s applied to the latter both from above and from below.

Our invention additionally includes other objects and novel features of design, construction and arrangement hereinafter more particularly pointed out or which may be apparent to those skilled in the art from the following description of certain embodiments of our invention as illustrated in the accompanying drawings.

In said drawings, Fig. 1 is a fragmentary longitudinal vertical central section through one form of normalizing furnace constructed in accordance with our invention; Fig. 2 is an enlarged transverse vertical-section on line 2-2 1n Fig. 1 and Fig. 3 is a fragmentary top-plan view, partiallyin horizonal section, of some of the conveyor rolls and adjacent parts. In Figs. 5, 6 and 7, which respective- 'ly correspond to the ligures just described, we vhave illustrated a normalizing furnace constructed in accordance with another embodiment of our invention and in which the conveyor rolls, instead of being superposed as in the first form, are arranged side 4by side in the same horizontal plane as will hereinafter more fully appear. Thus Fig. 4 is a fragmentary longitudinal vertical central section through the furnace, Fig. 5 an enlarged transverse vertical section on line 5-5 v of Figi/J: and Fig. 6 a fragmentary top plan view of'some of the conveyor rolls and adjacent parts. The same symbols of reference are used to designate like parts in the several figures, and all sectional views are taken in the directions indicated by the arrows on the section lilies.-

Referring now more particularly to that embodiment of the invention illustrated in Figs. 1, 2 and 3, the furnace, as best shown 1n Fig. 1, is of elongated form and arranged to provide three zones through which the sheets are consecutively passed as they traverse the furnace from one end to the other. These zones, respectively indicated by the brackets More particularly the furnace comprises a roof 1 which may desirably .be arched and supported on parallel, longitudinally extending side walls 2 joined at their lower extremlties by a floor or hearth 3, the Walls and roof being formed of bricks or other suitable, preferably refractory, material. End walls 4 and 5 are. also provided, the former being ierced with upper and lower openings form- 1ng doors 6-6 and the latter with corresponding openings forming doors 7--7, all of these doors being desirab y in the form of transversely extending slots of sufficient height to permit the introduction to and discharge from the furnace of the sheetswhich vare to be normalized,l The furnace roof may be rovided with a covering 1 of heat-insulating material to cut down radiation losses. The furnace is of maximum height throughout the length of the hot or final temerature zone b, and is desirably of slightly esser height throughout the zone c and of still lesser height throu hout the zone a, said zones, of course, being. m'the form of chambers 8, 9 and 10 respectively bounded by the roof, sides and bottom of the furnace and communicating with each other. The sidewalls and roof of the furnace may be supported and tied together in the usual way by .buckstays 12 and tie rods13 as indicated in .l Fig. 2 or in any other suitable way as-will be well understood by those familiar with the art.

In the form of the invention now being described two sh-eet conveyors, generally-,designated as 15 and 16, are provided and arranged one above the other in spaced relation. Each of these conveyors comprises a plurality of transversely extending shafts, those in the upper conveyor being designated as 17 and those in the lower as 18, respectvelyprovided with a plurality of laterally spaced discs'19rand 20 which are arranged in staggered relation on each adjacent pair of shafts so as to form a support for the sheets operativeV to convey them through the furnace when theshafts are rotated. The ends of the shafts are extended through the side walls of the furnace and any suitable means is pro-- vided for driving them. Thus each ofthe upper shafts may be furnished at one e'nd with a bevel gear 21 cooperative with, a similar gear 22 on a driving shaft 23 extending horizontally along the side wall of the furnace and the lower shafts similarly furnished of power and arranged to rotate in opposite directions so that the upper conve or 15 will be effective to move the sheets t rough the furnace in one direction, for example as indicated by the arrow adjacent thereto, while the lower conveyor will be effective to move'the sheets through the furnace in the opposite'direction as indicated by the adjacent arrow. The conveyor shafts may be journalled in supports 28 disposed outside of the furnace and the side walls of the latter provided with apertures for .the passage of the shafts of such size as to provide a certain amount of clearance therefor so that the shafts, as well as the walls themselves, are free to expand and contract under changes of temperature vwithout interfering with the operation of the shafts. While we have shown the shafts as solid, it will of course be understood that if desired they may bemade hollow and also that provision may be made for the effecting a circulation of water through them or for otherwise cooling them in any of thevvarious ways commonly employed in the art.

The heat requisite for the normalizing operation is introduced to the hot or final temperature chamber 8 of the furnace by means of burners extended through the side walls of the latter and we prefer to employ for this purpose an upper and a lower set of burners, the former being disposed adjacent the roof of the chamber and the latter adjacent the hearth 3 so that the heat will'be introduced to the chamber both above and below the conveyors. Thus, more particularly, we prefer to arrange a plurality of burners 30 at longitudinally'spaced intervals throughout the length of the cham-ber 8 and on opposite sides thereof so that the burning gases therefrom will be projected toward the center of the chamber-from each side thereof and preferably horizontally or substantially so, and we also provide another set of longitudinally spaced burners 31 below the` lower conveyor on opposite sides of the chamber so that the burning gases from, these burners will likewise be directed inwardly toward the center of the chamber from both.

to dispose thesel burners 4horizontally in a4 may be of any suitable construction and design adapted for the burning of gas, either natural or artificiah'or any other desiredv heating medium, and are preferably capable of individual regulation and soarranged that any desired number of them may be employed simultaneously as it frequently happens that not all of the burners are reqlured to produce the requisite .heating effect.

In order to ,confine within the final temperature chamber 8 as much as possible of' the heat derived from the burners` we provide between this chamber and the chamber 9 an upper baille 40 and a lower baliie 4l, these baflies preferably consisting of walls extending transversely across the chamber, the

baiiie .40 being disposed between the conveyors and the baille 41 below the lower conveyor. With the same end in view, We also provide adepending transversely extending baflle wall 42 adjacent the juncture of that portion of the furnace roof which is over the chamber 9 and that which is over the chamber 8, this wall extending down to a point uite closelyl adjacent Vthe upper surface of t e upper conveyor. At the opposite end of the final temperature chamber and for a like purpose, we provide similar upper and lower baiiies 43 and 44 generally corresponding to the bafiies 40 and 41,-but as the roof of the chamber l() is preferably, as hitherto stated, somewhat lower than theroof of the chamber 9 and thus lies 'more nearly adjacent the upper conveyor, it is ordinarily unnecessary to provide a depending bafHe wall corresponding to the wall42 vat the juncture of the roof of the final heating chamber and the recuperativel-jchamber l0.

As the sheets pass from the final temperature zone after having been raised to the requisite normalizing heat therein, it is desirable to quickly reduce their temperature to a point at which further grain growth is arrested and a practical fixation of the fine grain structure e'ected. We therefore provide means for bringing about a relatively rapid reduction in the temperature of the sheets at this point in their traverse through the furnace, and while said means may be of any form suitable for effecting the desired function we nd that good results may be obtained by providing a plurality of transversely extending, flattened pipes 46 adjacent the inner end of the roof of the recuperative chamber 10 and thus substantially above the bames 43 and 44, these pipes being suitably connected to a source (not shown) of cooling fluid, such as Water, which is circulated through the pipes. Thus as the subjacent sheets S are moved past the relatively cool pipes they are cooled or quenched to theVv requisite extent. Similarly and for a like purpose, we may provide a plurality of correspondingpipes 47 adjacent the inner end of the recuperative chamber 9 and above the lower conveyor so as to suitably-cool or quench the subj acent sheets S. as they are carried past the pipes by this conveyor; these pipes 47 may be conveniently'supported on the under side of the baille 40 and connected, like the pipes 46, to a convenient source of cooling fluid supply. As stated, however, While these flattened pipes, through which a circulation of cooling fluid is maintained,

are satisfactorily operative for effectingthe requisite rapid' cooling or quenching of` the sheets as they pass from-the final temperature chamber, any other means suitable for the performance of this function may be employed in lieu thereof if preferred.

ln the operation of the furnace the sheets S either alone or supported on a waster sheet are consecutively fed into the furnace through the upper door 7 in the end wall 5 and are then progressively carried by the conveyor entirely through the furnace and discharged therefrom through the upper door 6 at the opposite end thereof While in a similar way sheets S are-consecutively fed into the furnace through the lower door 6, either singly or each supported on a waster sheet, progres-` sively carried through the furnace by the lower conveyor and nally discharged therefrom through the lower door 7 at the opposite end. Heat is of course continuously supplied to the final temperature zone 8 in sufficient quantity to bringthe sheets S to the requisite normalizing temperature by the time they reach the left-hand end of this zone or chamber when viewed as in Fig.'1 and to similarly bring the sheets S to the requisite-normalizing temperature by los the time'they reach the right-hand end of said zone or chamber. As the sheets S pass beneath Vthe pipes 46 and similarly as the sheets S pass beneath the pipes 47, they are subjected to the action of the cooling medium which quickly lowers their temperature sufficiently to practically fix the fine grain structure of the sheets and prevent further graingrowth therein; the cooling or quenching effect, however, is desirably regulated so that the temperature of the sheets will not be reduced materially below the point at which the desired fixation of grain-structure is effected whereby as the sheets pass beyond their respective cooling or quenching points they still retain a considerab-le amount of residual heat which is radiated from the'sheets into tive .chamber 10 a considerable portion of their residual heat is given off within the chamber and'refiected downwardly by the low Y roof thereof to the subjacent sheets on the conveyor 16 which, entering the chamber through the lower door 6, are thus rogressively heated as they approach the fina temperature chamber 8 so that upon entering the same they are much hotter than when introduced to the fur- 10 nace with the result that they can be raised to the required normalizing temperature more quickly land with less. expenditure of heat than would be required if they entered the filial temperature zone at the temperature at v.15 which they were initially introduce to the -furducedto the furnace and thus need` less heat and less time to raise them to the normalizing temperature than would otherwise be required. Additionally, the radiation of heat l which takes place from the hot sheets S or S as the case may be during .their passage -throughthe respective recuperative zones or chambers results, bythe time the sheets are ready to pass ont of the furnace, in so reducing 36 the temperature of the sheets-as to prevent the formation of scale thereon after they are ejected from the furnace while, of course, all

of their heat'which has been transferred to the relatively cold incoming sheets has Vbeen vuse- 40 fully employed in reheating the latter and thus conserved andp utilized in .the performance of useful work with consequent enhancement of economy of operation. u

A further advantage of our invention resides in the fact that when waster sheets are used as a support for the-sheets to be normalized and are thus ejected from the furnace with the latter at one end or the other there.-

of, they may be immediately separated from `l thenormalized sheets and used on the other conveyor as supports for the unnormalized sheets which are passing into theV furnace fromA that end; 'the waster sheets being thus returned to the furnace before all of the heat which they have absorbed in their passage therethrough is dissipated, a further economyy is effected through-the conservation in this manner of heat which is otherwise lostfif the waster sheets are'allowedl'to eoolto-.atmos- L30 pheric temperaturel after leaving the furnace and before being returned thereto.

" When normalizing sheets of the same -thickveyor is substantially the same. However,

the furnace may be used with e ual facility for normalizing sheets` of two di erent thicknesses in which case as the thicker sheets naturallyl require a longer time for normalization-under lthe same temperature conditions than do the thinner sheets, that conveyor upon which the former are carried through the furnace may be run at a lower speed than the conveyer transporting the. lighter sheets ,thereby maintaining the heavier sheets in the .furnace for the additional time required to properly normalize them.

In Figs. 3, 4 and 5 we have shown a somewhat modified formvof our invention in which the conveyors, instead of being superposed, are arranged side by side thus ordinarily dccreasing the height ofgthe furnace but increasing its width for a given capacity.

Since ,in this form of the invention the construction of the side walls, bottom, roof and supporting means therefor are desirably substantially similar to that heretofore described, extended reference thereto would be superfiuous. As stated, however, theA furnace is usually made wider and lower as will be -apparent from an inspection of Fig. 5 and because of this decrease in height but a single 'set of burners 30'will generally be found sufficient, these burners being directed into the finafl temperature zone justbelow the furnace roo Two horizontally aligned series or sets of conveying rolls 50-and 5l are employed and extended respectively inward Athrough the side walls of the furnace which are provided with suitable openings for the passage thereof. The rolls are desirably of such length as lto leave av longitudinally .extending space between their adjacent inner ends along the center line of the furnace and those portions of the rolls within the furnace are provided with conveying discs 52, 53 corresponding to .the discs 19 and 20 heretofore-described. The

outer end of the rolls beyond the side walls of the furnace may be journaled in supports 55 and any suitable means provided for driv- `ing each setof rolls, for example, sprockets and chains generallydesignated as 57 and 58 may bev employed, or drive shafts and bevel gearing. of the general character of that shown 1n connection with the form of the inventionheretofore described.

For confining the heat as much as possible within the final temperature zone, the furnace may be provided with transverselyextending b-ailie walls 60 and 61 beneath the conveyor rolls at the ends of the final temperature zone while quenching means 62 .and 63 corresponding to the quenching means 47 land 46 are ldisposed respectively above the conveyors so as to quench the sheets as they `passfrom the-final temperature zone in either direction, In this form of the invention,

p however, the quenching means, for example the inner ends of the subja'cent conveyors and are thus respectively effective onlyupon the sheets carried thereby. v In this form of the invention the height of the recuperative 4chambers is' preferably the same, as shown in Fig. 4, instead of the roof of the chamber 9 being somewhat higher than that ofthe chamber 1 0 as in the other form of the invention previously described.;

thus there is no necessity for providing a transversely extending baiiie bet een cham-- ber 9 and the final temperature zo e corresponding to thebaiiie wall 42 in that form of the invention.

1n operation the two horizontal aligned series of conveyor rolls are rotated in opposite directions and the sheets S to be normalized consecutively fed thereto from opposite ends of the furnace so that they will be. carried through the furnace in' opposite directions and discharged from opposite ends thereof, the sheets being successively quenched by the superjacent quenching means as they pass from the nal temperature zone so as to effect substantial fixation of the grain structure in the manner already described. Whenwaster sheets are utilized' for supporting the sheets to be normalized in their passage through the furnace, the waster sheets as they are discharged` therefrom at the opposite ends thereof may be immediately returned to the furnaceupon the other and oppositely moving conveyor so as to conserve their heat as far as possible while, asin the .case of the other form of the invention, the heated sheets,

and waster sheets if used, after leaving the final temperature zone and during their passage through'the recuperative chambers are effective to raise the temperature ofthe adjacent incming sheets so that the latter enter the final temperature zone in a pre-- heated condition with consequent conservation of heat and reduction in operating costsas heretofore mentioned.

While we have hereinl described certain forms of our invention with considerable particularity, we do Vnotthereby desire orintend to conne ourselves thereto nor to any precise details of design, construction and arrangement of the various parts, nor to the use of any particular form, number or arrangement of burners, as the same being a matter of choice may be modiied in various ways and in numerous particulars without departingfrom the spirit and scope of the invention as defined in the appended claims.

Having thus described our invention, we claim and desire to protect by Letters Patent of the United States adjacent each end thereof and communicating therewith, a plurality of burners extended through the'walls of the central chamber and operable to heat said chamber to a predetermined temperature, means for'substantiall confining within the central chamber the eat generated by. the burners, adjacent conveyors extending through all of said chambers Jand respectively adapted to progressively carry material to -be normalized therethrough from opposite ends of the fur.

nace along vertically spaced paths and opposite directions and means disposed adjacent the inner end of each recuperative chamber operable to quickly reduce the temperature of said material as it passes into saidchamber from the central chamber.

2. A normalizing furnace comprising .a centralpchamber and a recuperative chamber 'adjacenteach end thereof and communicat ing therewith, vertically spaced conveyors.

extending 'in opposite directions through all p of said chambers, burners projecting into the central chamber and adapted to heat the latter to a predetermined temperature, means adjacent each end of the central chamber adapted to 'conne the heat therein, and

means adj acentsl .said last mentioned means operative to rapidly reduce the vtemperature of material disposed on the conveyors as it is carried thereby from the central chamber into the recuperative chambers.

3. A normalizing furnace comprising a central chamber and arecuperative chamber adjacent each end thereof and communicating therewith, said recuperative chambers being of less height than the central chamber and respectively of diiferent heights, a pair of vertically spaced conveyors extending through all of said chambers and respectively -operable to convey material through the furnace in opposite directions, burners projecting into the'central chamber and adapted to heat the latter to a predetermined temperature, means ad'acent each end of the central chamber a apted to coniine the heat therein, and means adjacent said last mentioned means operative to rapidlyl reduce the temperature of material disposed on the conveyors as it is carried thereby from the central chamber into the recuperative chambers.

4. A normalizing furnace comprising' a central chamber forming a linal temperature zone anda recuperative chamber adjacent each end thereof and communicating therewith, said recuperative chambers being of less height than the central chamber, a pair of superposed vertically spaced conveyors extending longitudinally through all of said chambers, means for driving the conveyors in opposite directions, burners extending into said central chamber operable to maintain the temperature of the latter at a predetermined degree and means adjacent the inner ends of the recuperative chambers operative to reduce the temperature of material disosed on the conveyors as it is carried therey out of the central chamber and into the recuperative chambers.

Y 5,. A sheet normalizing 'furnace comprising a central chamber forming a final temperature zone and a recuperative chamber of less height than the central chamber adjacent each end thereof and communicating Y therewith, a pair of sheet conveyors disposed one above the other and extendin longitudinally through all of said cham rs, means for driving the conveyors in opposite directions, burners extending into said central chamber from opposite sides thereof operable ,to maintain the temperature of the chamber at a predetermined degree,l means adapted to confine the heat generated by said burners within the central chamber, and means adjav cent the inner end of each recuperative chamber operative to quickly reduce the tempera- 'ture of the sheets as they are consecutively carried by the conveyors in opposite directions -from the central chamber and into the recuperative chambers. v

In witnessA whereof we have set our hands this 19th day of February, 1929.

ELMER MCVEY. WILLIAM -F. BARTHOLOMEW.

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