US2564849A - Lead pot furnace - Google Patents

Description

3 Sheets-Sheet 1 I||I|JI IIIIII.

Il I I f" nu VIIIIIII IIIIIIL m Aug' 21, 1951 c. M. MaCcHEsNEY LEAD POT FURNACE Filed' May 3l, 1945 Aug. 21, 1951 C, M, MaQ||EsNEY 2,564,849

LEAD POT FURNACE:

Filed May 51, 1945 s sheets-sheet 2 EN am.

Aug. 21, 1951 M, MaccHEsNEY 2,564,849

' LEAD POT FURNACE Filed May 51, 1945 5 Sheets-Sheet 5 Patented Aug. 21, 1951 LEAD POT FURNACE `Chester M. MacChesney, Chicago, Ill., assignor to Acme Steel Company, Chicago, Ill., a corporation of Illinois Application May 31, 1945, Serial No. 596,890

This invention relates to improvements in lead pot furnaces which are commonly used for annealing or cleaning strip metal or the like by running the strip material endwise through baths of molten lead, and the pimary purpose of the invention is to'provide an improved segmental lead pot adapted to be used in such a furnace for 12 Claims. (o1. 263-47) increasing the capacity and speed of operation thereof.- Y

In a lead pot furnace, the molten metal is contained in a comparatively shallow pot formed usually of cast iron, steel or semisteel and the strip material is moved endwise by power means and depressed between some of its supports suiciently to permit it to ,be progressively immersed in the hot metal during its travel. The lead pot is heated by burning gases or the like to the required temperature, a high temperature being employed for annealing purposes and a lower temperature when the molten lead is employed only for removing oil and dirt from the strip metal. In either case, the lead pot is very highly heated in order to maintain the lead in a hot molten condition and has to be of very substantial length to allow the strip metal to remain in the bath for a suitable interval of time. When the pot is of great length, its manufacture gives rise to molding and casting problems and when in use it expands unduly and is likely to warp and lose its shape so that it has to be discarded after limited use. This limitation upon the size or length of the lead pot has imposed a corresponding limitation upon the capacity and speed of operation of the furnace since the strip metal has to remain inthe molten bath for a substantial period in order to accomplish the desired results. With the length of the pot thus limited, it has been necessary to move thestrip metal through the bath at a relatively low speed in order to permit successive portions of the strip to remain submerged in the bath for the necessary interval of time, thus Yrestricting the output of the furnace.

The principal object of the present invention is to providean improved furnace, of the type referred to, having a lead pot made up of a plurality of connected segments or sections, each of which may be cast in one unit, thus permitting the composite length of the pot to be increased to any desired extent, within the limits of practical operation, and allowing a corresponding increase in the speed of movement of the metal strip and the output of the furnace. Another im-r portant object is to provide a lead pot for molten metal comprising metal sections connected together by a joint which causes a portion of the molten metal at the joint to solidfy and form a A further object is to seal between the sections. provide a lead pot for furnaces comprising a plurality of cast metal sections, the adjacent sections being connected by an intervening exible unit or section which is capable of compensating for expansion andvcontraction of the cast metal parts. Still another object of the invention is to provide a lead pot of the type referred to which comprises a pair of cast metal sections having outwardly tur-ned fianges which are 'clamped to corresponding flanges of an intervening connecting section, formed preferably of resilient nexible material, such as sheet steel or the like. Another object of -theinvention is to provide a lead pot comprising spaced cast metal sections and an intervening connecting section which is connected thereto by joints which are made fluid tight by solidified portions of the bath metal contained in the pot. Another object of the invention is to provide a lead pot furnace comprising a furnace structure formed in two or more units which are spaced apart, each unit supporting a section of a segmental cast metal lead pot, the sections of the lead pot being provided on their adjacent ends with means for establishing a connection with an intervening section which is formed of steel or the like and therefore capable of yielding to compensate for the expansion and contraction of the cast metal sections, the, intervening section being located in the space between adjacent furnace units so that it is not subjected to the direct action of the heat of the furnaces, the sections being connected by joints made fluid tight by solidified portions of the molten bath in the unheated region betweenthe furnace units. Other objects of the invention relate to various features of construction and arrangement whichwill appear more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which two embodiments of the inventionV are illustrated. In the drawings,

Figure 1 shows a side elevation of one form of lead pot furnace embodying the features of the present invention; l

Fig. 2 shows an enlarged top plan view of the furnace illustrated in Fig. 1 with parts thereof broken away;

Fig. 3 shows a longitudinal vertical axial section through the furnace on the line 3--3 of Fig. 2; f

Fig'. 4 shows an enlarged transverse vertical of lead pot embodying the presentV inventionY which may lbe employed` in the type of furnace illustrated in Fig. 1.

As illustrated in Figs. l to 5, inclusive, of theA drawings, the invention is embodied in a furnace IB mounted upon a concrete floor or other support I I and comprising two similarv and separate furnace units I2 which are spaced apartI to form an intervening space or chamber I3 in which a connection is made to the adjacentL ends ofr two:

cast metal lead pot sections I4 by means of an intervening connectingA section I5 formed preferably of steel plates or the like. The lead pot sections I4 are preferably formed of cast iron orv other material capable of withstanding the high temperature of the moltenA lead or other material which forms the bath I6 contained within the composite lead pot made up of the sections I4 and l5. Asr shown in Fig. 3, a metal strip I'I is adapted to be moved through the bath in the direction of the' arrow I8, being passed under an arcuate guide member I9 located at the left-hand or inlet end* ofthe lead pot and beneath a roller 20 mounted on a support 2I at the discharge end; of the lead' pot. The guide I9 and the support ZI may becarried by' an overhead supporting' structure, not' illustrated', which does not form a part of. the present. invention,

The furnace units I2 are carried by I-beams 23,v which extend transversely of the furnace with their lower fianges resting upon the floor or other support IZI' and each furnace unit' comprises a flat metal plateV 24A which rests upon the upper flanges of the I-'beams 23 and which supports the outer shell 25 of the furnace unit which is made up of a bottom. wall 25, side walls 25h, an outer end. wall 25e, and an inner' end wall 25d,

thus providing a hollow vessel of rectangular cross section which is. supported at its outer end by upwardly extending I-beams 26 having their lower ends restingV upon a longitudinal extension 24a of. the bottom plate 24 of that, furnace unit. The extension 24a' of the bottom plate is supported by short longitudinal I-beams 21 which rest upon the oor or. foundation. I I and the supporting posts 26 are reinforced by triangular brace members 28 which are attached to the outer flanges of the member 26 and to the extension 24a'- of the plate. The top ends of the I-beams 26 at the outer endof each" furnace unit are connected by an angle bar 29Y which is welded or otherwise securedthereto'. The bottom ends of ther-beams 26 aref secured to the base plates 24 'by other angle-bars 3l).v

At the sides of the furnace; the outer walls 25b are supported' by Vertical I-beams 3l which rest at their lower ends upon the bottom plate 24, this-plate being extendedy at the sides of the furnace as shown at 24hwhere it is supported by the projecting ends of the transverse horizontal I-beams 23. Other triangular brace members 32. are connected-to the upright members 30 and to the lateral extensions 24b of each base plate 24, thus rigidly supporting. the furnace walls in alateral direction..

At the inner end of each furnace unit I2, the end wallA 25d supportedl by an upright metal plate 33 which is attached to the adjacent botwhich is' tom wall 24 by an angle bar 34. These furnace walls 25d and the plates 33 are recessed on their upper sides to conform to the transverse under surface contour of the lead pot sections I4 and, adjacent these recesses, the end plates 33 are provided with angle bar brackets 35 which carry supports 36 of refractory material of the proper shape to conform to the lower surface: contours of the leadY pot'sections I4.

The walls of the furnace shells 35 may be formed of brick or other material adapted to withstand relatively high temperatures and the walls of these outer shells are lined with firebrick or other-refractory material adapted to withstand the veryhigh heatr which is created in the furnace for the purpose of maintaining the lead or other materialforming the bath I6 in a molten condition and at the desired temperature. As illustrated, the bottom wall 25a of each shell is protected by a floor or lining 39 made up of a number of parts which are separated by transversely extending division or bridge walls 40 formed of rebri'ckor the like and provided at their tops with cast metal caps 4I constructed as inverted channel-shaped` lmembers which em brace portions of. the uppermost bricks of the.

bridge walls 40` These channel`shaped members 4I extend beyond' the endsof the walls 4U intoA the side wall linings of the furnace hereinafter described, and their top surfaces lie-in one plane so that they serve as supports for the cast metal lead pot sections I'4, These Walls 40 are mounted.' directly upon the bottoml plates 24 ofthe furnace sections and the bottom walls 25l of the furnace' shells are divided by these bridge walls as the bottom lining 39 is thus divided. One of thebridge walls 41)'V lies in directcontact with the' inner end wall 25d ofthe outer shell of each sec-v tion, thus forming a refractory protection therefor, and thev outer walls 2'57 of the furnace shells are protected by inner linings 42 and 43 formed of rebrick or other refractory material. The lining portions 42' terminate short of the end' portions of the lead pot sections I4 but the lining portions 43 extend upwardly and terminate flush with the upper sur-faces ofthe outer end walls Z5ci of the outer shells.

The outer side walls 25b of the furnace shells are protected by linings 44 formed of rebrick or other refractory material which extend upwardly from the bottom Wall 25a to the plane of the upper edges of the side Walls 25h, as shown in Fig. 4; The upper edges of the outer Walls 25b and 25c ofv the furnace shells and the adjacent upper edges of the linings 43 and 44 are protected by a firebrick ledge 45 which projects over the inner edgesl of the linings 43v and 44, thus defining a rectangular opening 46'through which the lead pot sections I4 may be lowered to the positions where they' rest upon the upper surfaces of the bridge walls 40. The rebrick ledges 45 are held in place by metal plates 41 which are attached to the angle bars 29 at the ends of the furnace and to other angle bars 49 which extend along the sides of the furnace Where they are secured to the upper ends of the I-beams 3l. At thev middle of the furnace, the firebrick ledges 45 and the cover plates 4l are arched upwardly as shown at 45al and 42', respectively, in Fig. 3, to accommodate the intermediate lead pot section I5, the lateral edges of which extend upwardly above the level of the top edges of the cast' metal lead pot sections I4.

The divisionwalls or bridge Walls 40 which extendtransversely of the furnace units form a plurality' of combustion or heating chambers 5U aseasca z. the: clamps are located in the space i3 between theftwofurnaceunitsl2, the material of the bath.- Ifli is; not maintained in a1 highly uid condition irrtheoutwardly extending recesses 6l between the verticalA flanges l-dand the portions of the flanges Ig which flare upwardly" and outwardly therefrom, so that some ofV the lead or other material of the bath solidiiies in the crevasses between the two flanges idg and ld and forms a more or less thin layer or gasket which provides a fluidtight joint for the body portion of the bath which lies above it and is in liquid condi-V tion.. The outwardly flaring flanges serve not only to provide convenient means for permitting adjacent sections to be clamped together but also' asy heat dissipating means solidication of themetal located` between them', the flanges being of suicient area for this pur pose.

By locating the intermediate connecting section t5, the outwardly flaring flanges and the clamps El) in the space I3 between the two furnace units I2, thev solidification of portions of the bath metal to form fluidtight joints is facilitated andanother advantage is gained in that the intermediate resilient metal section l5 is not directly heatedby the action of any of the combustionchambers 5d. and. is therefore capable of withstanding the temperature to which it is subjected,A namely, that of the molten metal or the like which forms the bath I6. The steel plates or the like of which the intermediate section is formed', are therefore able to retain their temper andresiliency after continued use and are adapted to yield suiciently to compensate for any relative endwise movement of the two lead pot sections Ul' which may take place in response to temperature changes therein. The clamps til may also be continued in use for long periods without deterioration inasmuch as they are located in the space I3 and contact only with those portions of the flanges of the lead pot sections which are removed from direct contact with the molten bath.

In Fig. 6 of the drawings, there is shown a modified form of lead pot comprising a middle section S3; two end sections 6A, and two intermediate sections '65, illustrating the possibility of extending the length of the lead pot still further by'ernploying a greater number of sections which may be mounted within a furnace similar to that previously described except that it would comprise three separate furnace units instead of two and the connections between the middle section 63 and the end sections t! would be located in the spaces between these separate furnace units. Each end section t@ is constructed in the manner of the sections ifi previously described and comprises at its inner end an outwardly directed ange Eidg. The middle section Sii is formed from cast iron or the like, like the sections 84, and is provided at each end with an outwardly directed flange 63S similar to the flange idg heretofore described. The` two flanges 63g and *54g are connected by an intermediate member 65 which is identical in construction with the member l5 previously described, having outwardly directed parallel plates or flanges 55d which contact with the flanges 63g and @4g of the adjacent sections 63 and et, respectively, being secured thereto by clamps '5G which are identical in construction with the clamps Sli.

It will be apparent that, by means of the. present invention, a leadpot furnacehas beenprovided in. which the length of the lead pot may for causing the 8- beV extended to any desired degree in order to permit the traveling metal strip to remainsubf merged. inthe molten metal or the like for necessary interval of time even though its speed of travel be greatly increased as compared with the previous commercial practice. With the use ofthis invention, it is therefore possible to effect a great increase in the speed of treatment of. strip metal and the resulting output of the furnace without any decrease of the quality of theproductproduced.

Although certain forms of the invention have been shown and described by way of illustration, it will be understood that it may bev constructed rf. in. various other embodiments which come within the scope of the` appended claims. In the appended claims the flanges onthe lead pot sections arel defined asextending outwardly in the sense that they extend away. from the longitudinal axis of the lead pot. Although the receptacle for the molten metalV is referred to in the claims as a lead pot it will be understood that this term' is used broadly and is intended toinclude within itsscope. a pot which may contain any molten` "i metal or other liquid capable of being used for` treating the strip material passing therethrough.

I claimt.

1 .In a furnace, a leadpot comprising cast metal sections, and an intervening, flexible section secured thereto.

2.V In. a. furnace, a. leadV pot comprising cast metalV sections havingv outwardly turned flanges on their adjacent ends, a yielding section interposed between said first named sections and havving flanges,y contacting with said first namedy flanges,Y and means. for securing said contacting flanges together.

3. In a furnace, a lead pot comprising. cast metal sectionsv having outwardly turned flanges on their adjacent ends, a yielding section inter-y posedbetweensaid rstnamed sections and-having flanges contacting. with said first named anges, and a series of clamps embracing each pair of contacting anges for securing them together.

4. In. a. furnace, a. plurality of upwardly con-- caved castV metal. lead pot sections having outw-ardly directed flanges on their adjacent4 ends, and. an intervening upwardly concaved. sheet steel section. having outwardly directed endv flanges securedto saidrst named flanges.

5. In a furnace, a refractory furnace structure formed in a plurality of units spaced apart, a lead pot comprising a plurality of sections each carried by one of said units,. and a yielding section interposed between and connected tov adjacent ones. of said first named sections in a space betweentwo of. said units.V

6. In a furnace, a4 refractory furnace structure.

formed in a. pair of units spaced. apart, an upwardly concaved cast metal lead pot section cared by each of said units, means in said units for heating said lead pot sections, said sections being provided on their adjacent ends with outwardly turned. flanges, an upwardly concaved sheet metal section interposed between said first named sections in the space between saidl units and having outwardly turned anges which contact with said rst named flanges', and a series of clamps embracing each pair of4 contacting flanges.

7. A furnace comprising a lead pot formed in sections, and means for securingy said sections together to form a receptacle for a molten bathA metal, said. sections being formed to. provide the which communicate with each other through openings 4I)a formed in the bridge walls by omitting some of the rebricks of which these walls are constructed. These chambers 5D serve as combustion chambers for combustible gas discharged from the burners 5| which have their casings mounte-d in the outer side Walls 25b of the furnace shells and which have their nozzles 5I located in refractory tubular members 52 extending through the outer walls 25b and through the side linings 44, as shown particularly in Figs. 2 and 4. Adjacent the right-hand or discharge end of the furnace, as viewed in Figs. l, 2 and 3, the burners 5| are of smaller capacity than those burners which are located in the middle portion and adjacent the inlet end of the furnace, since less heat will be required to maintain the temperature of the contents of the lead pots near the discharge end of the furnace where the moving strip I 1 will have been heated by its previous contact with the molten bath. Gas for maintaining the operation of the burners 5| is supplied through pipes 53 and 54 which extend along the outer sides and ends of the furnace walls and which are connected with a suitable source of supply beneath the floor II as indicated by dotted lines in Fig. 2. The ilow of gas through these pipes to the individual burners is controlled by a series of valves 55, one of which is provided for each burner, and those burners which heat the inner ends of the furnace units I2 are connected to the supply pipes 53 while those burners which heat the outer end portions of the leads pots I4 are supplied with gas through the separate pipes 54, thus permitting an independent operation of the different groups of burners and the supply of different gases thereto if desired.

'I'he bottom walls of the combustion chambers 5I! are formed by the various sections of the bottom refractory linings 39 and these lining sections are inclined transversely of the furnace as shown in Fig. 4, the upper surface of each lining section being located at one end just below the outlet of one of the burners 5| while at the other end each lining section 39 is located flush with the bottom surface of an opening 56 which extends through the adjacent side lining 44 and through the outer side wall 25h. These openings permit the ash to be cleaned out of the combustion chambers at intervals and they are normally closed by doors 5l which are pivoted on metal tubes 58 mounted in those parts of the openings 56 which lie within the walls 25h. The doors 51 are hinged at their upper edges and normally remain closed due to the action of gravity.

The lining sections 39 are inclined in opposite directions in adjacent combustion chambers 50 and the burners 5| are located at opposite ends of these adjacent combustion chambers. Thus, the burners 5| along one side of the furnace units are staggered with respect to those along the other side of the furnace and burners at each side of the furnace open only into alternate combustion chambers. In this way, a substanti-ally uniform or other desired distribution of the heat may be brought about throughout the interior chamber of each furnace unit and the gases of combustion are permitted to pass freely from one combustion chamber to another so that there is a free distribution of the hot gases throughout the areas of the under sides of the lead pot sections I4.

Each lead pot section I4 is cast in one piece and is concave in cross section with the middle portion of its bottom wall I4El substantially flat and with the side walls I4b curving upwardly therefrom. At the outer end of the section, the end w-all I 4 curves upwardly. The top edges of the side and outer end walls of the lead pot sections I4 terminate slightly below the plane of the lower surface of the ledge 45, as shown in Figs. 3 and 4. The bottom wall of each lead pot section I 4 is increased in thickness to form a downwardly extending projection having a ilat surface I4d which is adapted to rest upon the upper surfaces of the channel-shaped members 4| which form the top members of the bridge walls 4U, as heretofore described. The lead pot sections are heldby gravity on these members 4| and are adapted to be moved into and out of the furnace chamber by means of a traveling crane or the like. For this purpose, the side walls I4b of the lead pot are provided at spaced intervals on each side of the vessel with integrally formed lugs I4e having upwardly directed recesses I 4f therein which are adapted to be engaged by the hooks of the crane.

At its inner end, the bottom and side Walls of each lead pot section I4 are flared outwardly away from the path of travel ofthe metal section Il, that is, the bottom wall I4rl is flared downwardly and the side walls I4b are flared laterally, thus forming a continuous outwardly directed flange I4g, the edge of which lies in a plane extending transversely to the longitudinal axis of the furnace. These outwardly flared portions |48 of the two lead pot sections are located in a space or chamber i3 between the two furnace sections I2 and also between portions of the side Walls 25b which are continuous between the two furnace units. These outwardly directed flanges I4g of the sections I4 are united with each other by the intervening connecting section I5 heretofore referred to.

The intervening section I5 is formed preferably of steel plates or the like having sufficient flexibility and resiliency to. permit them to yield in response to changes in temperature and to return to their normal positions by virtue of their resiliency. For this purpose, the member I5 comprises a central upwardly concave channelshaped member I5a having its top wall I5b directed upwardly and having its side walls I5c directed downwardly and welded or otherwise suitably secured to the top edges of plates or flanges I5d which form the ends of the section I5 and which extend downwardly and outwardly parallel to each other, as shown in Figs. 3 and 5, with their outer portions contacting with the inner surfaces of the outer parts of the flanges IIIg of the sections I4. The upper surface of the top wall I5b of the channel is located substantially in alignment or slightly above the top surfaces of the bottom walls I 4f* of the sections I4 so that the concavity of the section I5 forms with the concavities of the sections I4 a continuous chamber for containing the bath I6 through which the metal strip Il travels.

Each side flange I5d of the intermediate section I5 is secured to one of the flanges I4S of a section I4 by means of a series of clamps 60 each of which comprises a heavy U-shaped frame member G9a, adapted to embrace the coacting edges of the flanges I 4g and I5d, and a clamping screw 6Ib engaging one of the arms of the frame member and contacting with the outer surface of the adjacent flange I4f= for the purpose of clamping the two contacting flanges securely together. These clamps 69 are spaced apart at intervals throughout the extent of the flanges |42?u and |54, as shown in Fig. 5, and, inasmuch as 9 crevices at the joint between said sections whereby the joint is rendered iluidtight by solidied portions of said bath in said orevices.

8. In a furnace, a lead pot comprising metal sections provided on their contiguous ends with outwardly flaring flanges, and means for securing said flanges together to form a receptacle for a bath of molten metal, said flanges being formed to receive portions of said metal betwen them and to solidify said portions to form a sealing gasket between said anges.

9. In a furnace, a lead pot adapted to contain a bath of molten metal and comprising metal sections provided at their contiguous ends with outwardly directed. flanges adapted to receive a portion of said metal between them, and means for securing said flanges together, said flanges being constructed to provide suflicient heat dissipating surface to effect the solidication of said portion of said metal between them.

10. In a furnace, a lead pot comprising metal sections provided on their contiguous ends with outwardly aring anges, means for securing said flanges together to form a receptacle for a bath of molten metal, said anges being' formed to receive portions of said metal between them and to solidify said portions to form a sealing gasket between said flanges, and means for applying external heat to the major portions of said sections, the parts of said sections at and adjacent said flanges being unheated except by said bath.

11. In a furnace, a refractory furnace structure formed in a plurality of units spaced apart,

cast metal lead pot sections each carried by one of said units, means in said units for applying external heat to said lead pot sections, and means in the space between said units for connecting said sections to form with said sections a receptacle for a molten metal bath, said connecting means comprising parts adapted to effect the solidication of a portion of said bath to provide a sealing gasket between said sections, said space between said units being unheated except by said bath.

12. In a furnace, a lead pot comprising cast metal sections having outwardly turned fianges on their adjacent ends, a yielding section interposed between said rst named sections and having anges contacting said first named flanges, and means for securing said flanges together, duidtight joints between the contacting flanges being formed by solidiiied portions of the molten bath contained in said pot.

CHESTER M. MACCHESNEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 517,020 Bildt Mar. 27, 1894 1,501,887 Crapo July 15, 1924 1,683,129 Gaisman et al. Sept. 4, 1928 2,022,372 Hopkins Nov. 26, 1935 2,071,233 Merk Feb. 16, 1937

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