US1791404A - Furnace - Google Patents

Description

Feb. 3, i931. F. A. FAHRENWALD 97919404 FURNACE Filed Feb. 19. 1929 Pags-egwnd- I3 u agira :r

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Patented Feb. 3, 1931 UNITED STATES FRANK A. FAHRENWALD, F CHICAGO, ILLINOIS FURNACE Application led February 19, 1929. Serial N'o. 341,178.

This invention relates to furnaces for heattreating metal strips, sheets, plates, bars, packs and other articles and has particular relation to furnaces of the continuous process type wherein the articles operated upon are conveyed mechanically through at least the heated zone, and preferably also the cooling zones, on suitable rollers which are thus exposed to the full effect of the furnace. In

my Patent No. 1,623,469, issued April 5, 1927, I described and claimed a fundamentally new type of furnace roll for use in apparatus of this kind wherein the rolls, instead of being cooled byva circulating liuid as theretofore, l5 were allowed to assume the full furnace temperature, being made with reference to ce1- tain essential features of construction to enable the maintenance of rigidity despite the weakening of the metal due to the high temperature and by which the conveyance of heat along-the metal towards the bearings was diminished to an amount which the bearings could successfully dissipate. The objects of the present invention are the provision of another type of furnace roll, also operated at the full furnace-temperature, but supported and operated in a new and different manner; the provision of a type of roll that can be made of lighter weight and of different types of metal 3U than the rolls of my former patent; the provision of a construction of roll-furnace wherein any defective roll can be replaced with a minimum of interruption to the operation; the provision of a roll-type furnace containing a combination of carrying-rolls and driving-rolls wherein the saving of weight and money effected by the combination shall more than offset the added complication produced by the increased number of the parts; 4* the provision of a roll-type furnace wherein the driving elements are operated at an 1ncreased speed and hence operate more smoothly and with less strain; the provision of a roll-type furnace of the type described 4* in which wrought-metal rolls can be employed; while further objects and advantages Vof the invention will become apparent as the description proceeds. i

-In the drawings accompanyin and forminga part of this application, 1g. 1 1s a 'or carrying-Wheel 8.

vertical longitudinal section through a steelnormalizing furnace containing my provements; Fig. 2 isa view lookin down thereon, partly in plan and partly roken away at different levels; Fig. 3 is a. vertical- 55 cross section of the furnace shown in Figs. 1 and 2; Fig. 4 is a similar cross-section showing cantilever shafts and other minor modifcations; Fig. 5 is anenlarged` detail-sectional view of one end portion of a dry-shaft assembly; Fig. 6 is a horizontal sectional view of part of the furnace shown in Fig. 4; Fig. 7 is a cross-section of a furnace showin my improvements as applied to a wet sha assembly; Fig. 8 is a cross section of Fig. 7 on 65 the line 8 8; and Fig. 9 shows another modiic'ation. i

Such a furnace as herein contemplated comprises an elongated chamber l defined ordinarily between a hearth or ioor 2, sidewalls 3, 3, and roof. The side walls are ordinarily reinforced by vertical metalmembers 5 5 ordinarily called buckstays, and

ythe side-walls 3 3 are formed with spaced horizontal apertures 6'for the passage of ro- 75 tatable shafts 7, provided just inside each side wall of the furnace with a metallic disk This shaft may traversc the furnace chamber from side to side as shown inlligs. 2, 3, 5, and 7, or it may be 8o discontinued inside the furnace chamber as shown in Figs. 4 and 6, leaving merely subends as shown at 73,'although with certain secondary changes in the mode of supporting and driving said shafts vas willhereafter be explained. W'hether these shafts are continuous or discontinuous, the 'disks thereon constitute a support for aseries of cylindrical, metal, rolls 10-10, the diameter of each roll beingsutfciently greater than the distance between the peripheries of adjacent disks to prevent falling therebetween and sufficiently less than the distance between the centers of adjacent disks to avoid interference with the adjacent rolls. j

The length of. each roll is preferably such as'to bring its ends fairly close to the'furnace walls although care must be taken to prevent contact therebetween, for which purpose the rolls and disks are formed with suitable in- .1.00

terengaging ribs, rooves, or flanges, care also being taken to a ord sufficient looseness to enable the necessary thermal expansion which is sometimes rather great.

Many variations of the above mentioned general features are possible, especiall as regards the modes of supporting, journa ing', driving, etc. In Fi 2, 3, and 5, horizontal angle irons 12 are bo ted to the buckstays and serve to support massive metal bearings 13 in which the shafts are rotated by means of suitable driving devices such as the Wormgears 14 meshing' with worms 15 carried by the longitudinal shaft 16. In the form of the invention shown in Figs. 4 and 6 each of the com aratively short shafts 7 is journaled in two arings 13h-13" located outside of Athe furnace wall and rigidly supji'rted at ends of these rolls.

different distances therefrom by means of a suitable yokefmember 18.

To preserve the pro r lation between the dis relative axial reand rolls I have shown several ex edients. In Figs. 2 and 3, each roll is provided at one end with a narrow circumferential groove 19 ldefining a flange 20 and closely receiving one of the disks 8, the op osite end of the roll having a more e'xtende reduced ortion or circumferential recess 21 Idefine by a shoulder 22, the latter being sufficiently spaced from the other disk to enable expansion and contraction. In order to avoid the necessity of having adjacent disks 8-8 strictly in the saine plane it is well, when this arrangement 1s em loyed, to have adjacent rolls 10 reversed en for end that the grooves 19 come in opposite ends thereof as shown in Fig. 2. Another sible arrangement is to form each end o the roll with acylindrical. reduced ortion 21 as shown in Fig. 7 to enable the shoulders thereby defined to fit between the disks 8--8. lAnother very satisfactory mode is toemploy plain cylindrical rolls 10 devoid of grooves or flanges and to form the disks 8" with flanges 23 which overlap the In this case* the anges 23 are preferably omitted from alternate disks as shown in Fig. 6,

Veach end is sufficient guidance for the two rolls which engage the same, and in this way the necessity of locating adjacent disks in the same plane is-avoided.

Preferably the shaft 7 or 7, and disks 8 or 8 are made of metallic alloy having a suiliciently high melting point and rigidity under high temperature to enable them to be operated at full 'furnace temperature, without artificial cooling. Inasmuch as numerous'alloys of this nature are well known and on lsale on the market I do not consider it necessary tojsuggest any formula therefor.

. Any one of numerousexpedients can be em- .ployed along these shafts so as to keep the bearings to restrict `the conduction of heat suiciently c ool for successful operation. To

since one flange at this end it is desirable to make the end por- .tions of the shaft hollow as shown in Figs.

and also to prevent transfer of heat by con- '7.0

vection of the furnace gases' around the shaft by providing ,suitable acking 24 around the same, held in place if desired by means of metal plates 25. Convection-flow of heat inside the shaft is ordinarilyy so limited by thefriction of the gas in the bore as not to be troublesome, though this can also be further arrested by a suitable plug 26 of cement or cla or asbestos or other material. In the case o the cantilever shafts shown in- Figs. 4 and 6, stoppage of gas flow from, the 4furnace chamber is essential.

With the cantilever type of shaft shown in Figs. 4 and 6 it is ordinarily sufficient to employ a plain cylindrical hollow shaft section, 85

preferably vclosed at the inner end or at .least at some point so as to prevent outliow of furnace gases therethrough. Owing to the fact that the entire load is n every case car' ried close to the furnace wall, the load car 90 rying portions of the shafts are largely shlelde shaft 7 traverses the entire furnace chamber,

the middle .portion thereof has only to carry' its own weight and hence can be made comparatively small.

My improvenients lend themselves also to use with water-cooled shafts. In Fig.- 7 the shaft 7 b is provided at each end with a swivel joint connected to suitable fiuid pipes 30-30 100 lby which cooling iiuid is passed through the v shaft, thus allowing it to be made of common steel if desired. Ordinarily this is undesirable practice both because of the large amount of heat abstracted by the iiuid (in case of water often as much as 50% of the entire fuel value), and also objectionable because of the chilling effect on one side of the articles being' treated. With the constructions herein shown these objections can be largely overcome by enclosing each of the shafts 7 b in a housing or shield 3l of inverted U-shaped section, resting on the iioor 2 of the furnace, the length being such as to fit between the disks 8 8, and

the width being such as to clear the rolls theinselves. .n

These rolls are in all cases made of such an alloy as will withstand the full furnace temperature, but owing to their short length,

their simplicity, and their freedom from bearing parts, they can be made very light and in` expensive. Furthermore, owing to their simplicity, especially when made plain as shown in Figs. 4 and 5, they can be made of alloys whichA are too hard to be readily machined,

mechanical connections thereto, any roll from the furnace heat. Even the which fails can be ahnostV instantly removed and replaced merely by displacing a section of the furnace roof or side wall, which is preferably made in separate sections 11G-a0 for this purpose.

Therolls may be made either plain surfaced as shown in Figs. 4 and 5 or formed with peripheral `projections 32 thereon as shown in Figs. 1, 2, and' 3. These rojections can be either integral or applied ut each is preferably so spaced from one end of the roll as that a recess willbe formed at an equal distance from the opposite end so that when two identical rolls are laid side by side and end for' end the projections of the one will fall opposite the recesses of the other, thus requiring only one dimension of yroll to be maintained. The diameters of the rolls and disks may bear any desired ratio to each other. Then it is necessary to provide housings 31 asi'shown in Figs. 7 and 8, it is necessary to make the disks considerably larger than their shafts and hence'sometimes comparable in size to the rolls; but-whenever possible it is preferable to make the disks smaller than the rolls, thereby lenabling the shafts to be operated at a. higher speed, which reduces the mechanical strain thereon and enables a steadier drive. j

In Fig. 9 I have shown afurther modification in which the rolls 10b are provided at their ends with circular disks 32 which rest Ace directly on the shafts 7,the latter requiring no enlargements, and even permitting a slight reduction in size as shown.` These enlargements or disks when employed may be either integral with the shafts or separate therefrom. lt prefer to employ at least a slight enlargement as facilitating manufacture and use.

lt will be apparent from the foregoing that a great many modifications in detail can be made within the scope of my inventive idea and accordingly l do not limit myself in anywise except as specifically' recited in my several claims which I desire may be construed each independentlyof limitations contained in other claims. 't

Having thus described my invention what I claim is:

1.A A. metallurgical furnace having apertured side walls, horizontal shafts located in said apertures and journaled outside of said walls` circular disks carried by said shafts close 'to the side walls, and conveyor rolls eccentric to-said shafts carried by said disks in rolling relation.

2. A metallurgical furnace having apertured side walls, a row of shafts having their ends projecting outward through said apertures and journaled outside of said-` walls, said shafts having circular carrying portions close inside said side walls, and a horizontal conveyor roll having an end received between and supported'by the carrying portions of said roll being greater than the distance between the peripheries of adjacent carrying y portions.

3. A metallurgical furnace having apertured side walls, horizontal shafts located in said apertures and journaled outside of said walls, circular disks carried by said shafts close to the side walls, conveyor rolls carried by said disks and located wholly outside of the linedeined by the shaft axis, whereby the weight of said rolls and ofy their load is sustained close to the furnace walls and said rolls are readily removable, and means for rotating all of'said shafts in the same direction.

4. A hietallurigical furnace having apertured side walls, a row of shafts having their ends projecting outward through said apertures and journaled outside of said walls, circular disks carried by said shafts close to said side walls, a horizontal conveyor roll having an end received between and supported b v each adjacent pair of disks, and means for rotating said shafts opposite to the desired direction of rotation of said rolls.

5. A metallurgical furnace having apertured side walls, a row of shafts having their endsj projectingoutward through said apertures and journaled outside of said walls, circular disks carried by said-shafts close to said side Walls, ahorizontal conveyor roll having an end received between and supported by each adjacent pair of disks, interfitting provision between said rolls and certain of said disks whereby relative axial movement is limited and means for rotating certain of said disks whereby said rolls are rotated.

6.`In a metallurgical furnace, a series of parallel horizontal conveyor rolls located close together and traversing the furnace,

chamber from side to side and a series of ioo shafts supporting and rotating said rolls and I journaled outside the furnace chamber, said rolls being free from said shafts and readily removable.

7. In a metallurgical furnace, a series of parallel horizontal conveyor rolls located close together and traversing the furnace chamber from side to side, and a series of shafts supporting and rotating said rolls and journaled outside the furnace chamber, said shafts traversing said side walls and cular carrying low rolls of high temperature alloy traversingV in one piece the distance between opposite disks having their ends resting externally on said disks in rolling relation whereby their Weight is sustained close to the furnace wall.

11. In a metallugical furnace, the combination with -apertured side walls, of horizontal projecting from said apertures, bearings for said shafts outside of said side walls, disks carried by said shafts close inside said side walls, hollow rolls of high temperature alloy having their ends resting externally on said disks whereby their weight is carried close to :the furnace walls, and said rolls are rendered readily removable, and means outside the furnace wall for rotating said shafts, said furnace having a sectional removable roof.

12. In a metallurgical furnace, the combination, with apertured side walls, of horizontal shafts traversing said side walls, bearings for said shafts outside'said Walls, disks carried by said shafts immediately within such walls, the disks and bearings at one side of the furnace being coaxial with the disks and bearings at the opposite side of the furnace, means for rotating all of said shafts in the same direction, and hollow rolls of high temperature alloy of greater diameter than said disks and having their ends carried by said disks.

13. In a metallurgical furnace, in combination, carrying disks with horizontal axes located close inside the side walls, hollow rolls having cylindrical end portions located between adjacent disks and partly overlapping their upper surfaces in supported relation, said rolls and at least a part of said disks having cooperating shoulders whereby relative endwise movement is limited, and means working through said side walls for supporting and operating said disks.`

14.- In a furnace, a series of horizontally spaced supporting disks along each side wall journaled upon parallel horizontal axes, at least a part of said disks having anges at their edges which are nearest the furnace a hollow metal roll having cylindrical portions resting on said disks, the length of said roll being such as to enable it to fit between the flanges of opposite disks, and means working through the side walls for supporting and operating said disks.

Walls,

-jections adapte-d 15. In a furnace, a series of horizontally spaced supporting shafts journaled outside of the furnace on parallel horizontal axes, and projecting through the furnace walls, and a series of load carrying rolls loosely and removably carried by the portion of said shafts inside the furnace.

16. In a furnace, a series of horizontally spaced supporting and driving disks journaled on parallel horizontal axes, and a series of load carrying rolls resting on and supported and operated by said disks, each of said rolls having external peripheral proto interfit with the projections of adjacent rolls and said projections being spaced unequally from opposite ends of said rolls whereby such interfitting is secured by the making of adjacent rolls identical in measurements and reversing them end for end.

17. In a furnace, a series of horizontally spaced supporting disks journaled on parallel horizontal axes, and a series of load carrying rolls carrie-d by said disks, adjacent rolls being identicalvand each having a peripheral projection at a given 'distance from one end and a peripheral recess at an equal distance from the opposite end, adjacent rolls being reversed end for end so that the projection of the one shall lie opposite the recess of the other.

18. In a metallurgical furnace, the combination with apertured side walls, of horizontal shafts traversing the furnace chamber and having their extremities projecting through said apertures, bearings for said shafts outside of said side walls, disks carried -by saidshafts close inside said side walls, hollow rolls of high temperature alloy having their ends located between and resting partly upon adjacent disks, and driving means operatively connected to said shafts outside the furnace.

19. In a metallurgical furnace, the combination with apertured side walls. of horizontal shafts traversing the furnace chamber and having their extremities projecting through said apertures` bearings for said shafts outside of said side walls, disks carried by said shafts close inside said side walls, hollow rolls of high temperature alloy having their ends located between and resting partly upon adjacent disks an-d stationary, heat-insulating shields surrounding and protecting the parts of said shafts between the disks thereon.

20. In a metallurgical furnace, the combination with apertured side walls, of horizontal shafts traversing the furnace chamber and having their extremities projecting through said apertures, bearings for said shafts outside of said side walls` disks carried by said shafts close inside said side walls, hollow rolls of high temperature alloy having their ends located between and resting partly upon adjacent disks and inverted lOl ICI

trough-shaped shields surrounding and proshafts and rotatedI thereby in the opposite tecting the partsof said shafts between the disks thereon, said shields supported by the furnace floor.

21. In a metallurgical furnace, the combination with apertured side walls, of horizont-al hollow shafts traversing the furnace chamber and having their extremities projecting through said apertures, bearings for said shafts outside of said side walls, disks carried by said shafts close inside said side walls, hollow rolls of high temperature alloy having their ends located between and resting partly upon adjacent disks. connections for circulating cooling luid through said shafts, and stationary heat-resisting shields surrounding and protecting the parts'of said lshafts between the disks thereon.

22. In a furnace, a series of horizontal load-carrying rolls inside the furnace chamher, disks inside said chamber on and bctween which said rolls are laid, and means located outside of said chamber for support ing and rotating said disks, the diameter of the disks being less than that of the rolls.

23. The combination with a furnace having apertured side Walls and roof of individually removable sections, of supporting disks located in the furnace chamber with their axes parallel and horizontal, load carrying rolls slightly shorter than the distance between said side Walls removably carried on the exterior of said disks, and means working through the apertures for supporting and rotating said disks.

Q4. In a metallurgical furnace, a series of hollow conveyor rolls located side by side in the furnace chamber, and a series of supporting shafts projecting through the furnace wall between and beneath said rolls and supporting said rolls, said shafts journaled outside the furnace wall.

25. In a metallurgical furnace a series of conveyor rolls located side by side in thefurnace chamber, a series of supporting shafts located below and outside said rolls and rotating in the opposite direction therefrom, and means Working through the furnace Wall for supporting and rotating said shafts.

26. In a metallurgical furnace a series of conveyor rolls located side by side in the furnace chamber, a series of supporting shafts journalled outside and projectingthrough the furnace wall, the eXteriors of said rolls resting on said shafts and the furnace chamber having a removable closure portion adjacent each roll.

27. In a furnace, a plurality of horizontal I spaced parallel shafts projecting through the furnace Wall and journaled outside the same, means rotating all said shafts in one direction, and load conveying members located in the furnace chamber and resting on said direction.

signature.

FRANK A'.l FAHRENVALD.

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