US2273821A - Sintering machine - Google Patents

Description

Feb. 24, 1942. c. E. AGNEW SINTERING MACHINE Filed May 7, 1940 3 Sheets-Sbeet l e I m 1 n m 1 m m m m m A E X; 2 W 2: x 2 H A wfk I l 6 M L C Y 2 2 WW MWN NW Feb. 24, 1942. c. AGNEW SINTERING MACHINE Filed May '7, 1940 3 Sheets-Sheet 2 INVENTOR. CharlcsEf flymw, BY m A TTORNE Y.

Feb. 24, 1942. c. E. AGNEW 2,273,821

S INTERING MACHINE Filed May 7, 1940 S SheetS-Sheet s INVENTOR. Ch 047 e315. flylzew,

ATTORNEY.

Patented m. 24, 1942 UNITED STATES PATENT OFFICE SINTERING MACHINE Charles E. Agnew, Norristown, Pa. Application my 7, 1940, Serial No. 333,849

18 Claims.

The present invention relates to sintering machines for sintering or roasting 'flnely comminuted ore or other finemetal bearing material to convert it into agglomerated masses suitable 'for charging into a blast furnace, and particularly to that general type of machine in which an endless train of.grate pallets is passed over and around under the top of'a wind-box, the charge of material in the pallets being sintered during passage of the pallets over the top of the windbox by combustion maintained by a continuous down draft of air through the material into the wind-box, the sinter cake being dumped out of the pallets as the latter are inverted for theirreturn passage back under the top of the windbox.

A large item of expense in the first cost and maintenance of sintering machines of this general type is the first cost and the cost of repair and replacement of the pallets which run in number from 85 .to 90, and the repair and replacement of their roller supports. An important object of the present invention is to greatly reduce this item of expense by the provision of .a movable pallet train in which the pallets are without wheels and are simplified to an extreme degree,

' capable of being formed as a simple casting revision of a strong and sturdy roller support for the pallet train separate from the individual pallets and repairable and replaceable independently of the, pallets, and which because of its independence of the pallets, may be composed of rollers as numerous and as large as desirable with high quality dustproof bearings and with any lubricating system desirable, preferably a pressure lubricating system, without adding to the weight and cost of ther pallets. This feature of the invention providesa roller support system in which the rollers will have a life several times as long as in the case of rollers carried by the pallets, and makes for a marked improvement in the reduction of friction with resultant saving in power and reduction in wear.

In the operation of such machines a large item 1 air into the wind-box requiring in the average ma- I chine a motor of a capacity in the neighborhood of 300 horsepower for the draftinducing fan, which power requirement is high compared with the 25 horsepower motor used to propel the train of pallets. Foul air in the sense here used indicates any useless air which may enter the windbox without passing through the charge of material being sintered in the pallets, such as air that may pass directly into the wind-box through thejoints between the opening at the top of the wind-box or the joints between the abutting ends of the pallets while over the wind-box opening;

Increased cost' of operation due to entrance of foul air into the wind-box is amplified by the fact that such air is relatively cool and dense and acts to cool and increase the density of the air in the wind-bop: with consequent increase in load on the draft inducing fan and increase in power consumption. According to the present invention. the above losses are substantially eliminated by improvements in the wind sealing of the machine, particularly by the provision of a double seal, one for the joints'between the pallets and the top of the wind-box and. another for the joints between the abutting ends of the side walls of the pallets, the wind seal being so arranged in relation to the pallet roller supports as to be protected from fouling by a mixture of dust and oil,

vapor or seepage oil from the bearings of the rollers, and'at the same time shield the bearings against dust. Q

Asmarked disadvantage of machines of this type at present in use is the difllculty of maintaining proper lubrication of the pallet rollersupports dueto heating of the bearings by direct conduction from the pallets which causes a thinning of the necessary heavy lubricant with resultant loss by seepage. The use of even a simple pressure system is prohibited by the continuous movement and repeated change from an upright to an invertedposition the pallets and their bearings. These disadvantages are overcome in the present invention by the provision of stationary roller supports for the pallets with the entire radial depth of the rollers interposed between the hot pallets and the lubricated-roller bearings with only a small portion of the-tread surface of the roller in actual contact with the pallet at any"- time. This makes for a minimum amount of direct heat conduction between the hotpallets and the supporting rollers'while the rol er bearings being stationary may be provided wit any kind of lubrication desirable, and makes possible a cooling of the bearings by a water line which is .a feature of the present invention.

- A further object of the invention is to reduce the amount of gap in the train of pallets near the discharge end, which gap is necessary to allow for heat expansion and to prevent jamming of the machine should a pallet slip a cog in its engagement with the sprocket wheel or other driving means, and must accordingly be at least equal to the distance between the teeth of the driving sprocket. In machines at present in use in which the pallet supporting wheels or rollers are carried by the pallets the pitch of the sprocket wheel is necessarily large relative to the length of thepallets, usually about 8 inches for a 24 inch pallet. This results in'an 8 inch gap at the discharge end of the train of pallets through which each pallet drops against the preceding pallet as it makes the turn down around the dis-' charge end of the machine. As the combined weight of a pallet andsinter cake is from 1,000 to 1,500 pounds, the hammer blow imparted to the bottom adjacent edges of the pallets wears sprocket or gear 20 from the feeding or charging and upsets these edges which further increases the distance of the drop and forms burrs along the edges which interfere with any type of seal located at the bottom of the pallets. According to the present invention this end drop is reduced to a minimum by providing the pallets near the bottom with racks of small pitch relative to the pallet length for engagement with a driving sprocket or gear of like pitch. Preferably this pitch is in the neighborhood of 3 inches for a 24 end 2! near where they pass. under the usual charging device 22 and ignition burner 23 over the wind-box, inlet opening l2 to the discharge end 24.

More specifically,'the track-way according to the present invention is a stationary roller trackway constituted of a. series of stationary rollers 25, 26 and 21, which support and guide the wheelless pallets l8 by engagement with hearing, surface portions on the latter. These bearing, surface portions comprise the downwardly facing surface portions 28 for engagement with the rollers 25 of the upper-track section M; the upwardly facing surface portions 29 for engagement with I the rollers 260i the lower. track section and the upwardly facing arcuate surface portions 30 for engagement with the rollers 21 of the curved,

track sections [6 and IT. The rollers of both the upper and lower track sections are inwardly and downwardly inclined and the cooperating bearing inch pallet. Thus the drop is reduced to 3 inches,

which greatly lessens wear. Another advantage of the low pitch rack and driving gear is that it enables the drop to be adjusted in small increments of, for example, 3 inches in the case of a 3 inch pitch. I

Various other objects and advantages of the invention will be apparent from a perusal of the following specification and the drawings accompanying the same.

In the drawings:

Fig. 1 is a side elevation of the machine shortened in length by omission of a central portion.

Fig. 2 is a section on the line 2-2 of Fig. l and on a larger scale.

Fig. 3 is a large scale view of' the discharge. end of the machine with portions of the pallets in section to show the rack and sprocket engagement.

Fig. 4 is a section on the line 44 of Fig. 3.

Fig. 5 i a fragmentary perspective view of a pallet.

Fig. 6 is a large scale fragmentary side elevation of the top portion of the machine near the surfaces on the pallets correspondingly inclined as shown in Fig. 2 to maintain the pallets properly centered and aligned with respect to the trackway. Similarly th rollers 21 are inclined toward each other and away from the center of curvature of the curved track section and the arcuate bearing surfaces on the pallets correspondingly inclined, as shown in Figs. 4 and5. For driving the pallets around the track-way, the pallets are provided with a pair of racks 3 l countersunk in the bottom along each side for engagement with the driving sprocket 20, and an idler sprocket 32 at shown in Fig. 3, and it will be understood that the Referring to the drawings in detail and first to v I Figs. 1 and 2, the machinecomprises in general a supporting structural frame member ID supporting a series of wind-boxes ll terminating at the top in a wind-box inlet opening 12 (Fig. 2)

and connected through bifurcated extensions l3 extending downwardly around the sides of the machine to an exhaust chamber and exhaust fan notshown and which may be of any known or other suitable form. A track-way having upperand lower track-way sections I4 and I5 connected by outside curved end sections it and I1 is arranged to guide an endless train of pallets l8 over and around under the top of the windchine.

driving sprocket at the charging end of the machine similarly engages the racks in the pallets to impel them toward the discharge end of the ma- It will be understood that the idler sprocket 32 may be omitted entirely, especially vwhere the train of pallets is sufficiently short to permit the lower line of empty pallets to be propelled along the track-way by the weight of the pallets in the curved track section at the discharge'end, or where'the lower return track-way is inclined toward the bottom of the driving sprocket 20. Thepallets are shaped and proportioned with relation to the other parts of the machine as shown in Fig. 2, so as to pass over the wind-box opening l2, with a slight clearance between the top edges 33 of the wind-box opening l2 and the open bottom of the pallets.

As the pallets move beyond the wind-box opening l2 to the discharge end of the machine, they pass around onto the curved extension 35 of the upper track section M, at the same time engaging the rollers 21 of th outer curved track section 46 through their arcuate bearing surface portions which insure uniform engagement of the pallets with the rollers during their travel around the discharge end of themachine to the lower track section. At the location where the pallets in this turning movement approach the horizontal inverted position there is no necessity for supporting the pallets from their bottom bearing surfaces wherefore the curved extension is discontinued at this point but from here on the curved track section 16 is continued around to a horizontal tangential plane to maintain support of the pallets through the arcuate bearing surface portions 30 until they reach the position indicated at 36 in Fig. 3 where they pass on to the rollers 26 of the lower track section l5, the pallets being then supported by the straight bearing surface portions 23. The pallets continue to travel back along the lower track section in the direction indicated by the arrow 31 between the bifurcated extensions I3 of the wind-box, as indicated in Figs. 1 and 2, to the driving sprocket 20 which by engagement with the racks in a manner similar in all respects to that of the idler sprocket 32, propels the pallets around the curved track section I! and the curved extension 38 of the upper, track section l4 onto the section l4 where the pallets again assume an upright horiprovided at either end of the machine above the sprocket wheels. These sections have their rollers arranged to bear on the upwardly facing straight bearing surface portions 29 of the pallets, and may be spring pressed or otherwise yieldingly pressed downwardly in any suitable manner. While the pallet supporting rollers such, for example, as the rollers 25 (Fig. 2) are here shown in conventional form and as a simple roller, spindled on a simple bearing support 4|, it is to be understood that they maybe of any known or other suitable form preferably of the dust-proof bearing type and with some known or, other suitable form of forced lubrication. This use of more elaborate roller bearings than heretofore permissible in such machines, with economy in maintenance, is made possible in the present machine by the fact that and independent of the pallets as regards wear and upkeep. Any error in alignment caused by wear of the rollers can be readily adjusted by shiij s placed under the base of the roller support.

Further advantage may be taken of the fact stationary by installing a cooling pipe 65 along beside the rollers 25 in thermal contact with their bearing supports 4| to cool the bearings and so offset any tendency to over heating thereof by heat conduction or radiation from the hot pallets.

It" will be clear from an inspection of Figs. 5, 8

and 9, that the wheelless pallet here disclosed may be made as a simple casting with little or no machining, which makes complete replacement cheaper than repair.

In the machine as here illustrated, the'dimem sions and relative proportions contemplated are is 24 inches and it is desired to shorten the drop by 3 inches to make up for wear, a 24 inch pallet present machine by the provision of a wind sealed casing 52 formed by the partition elements 42 and 43 (Fig. 2) extending along either side of the mathe side of the wind-box opening to the outer side of the pallet with which sealed connection is'maintained by a wind seal flap 44. The flap the rollers are stationary and are separatefrom that the rollers and their bearing supports are 44 is secured to the top edge of the side casing element '43 by rivets 45 or other suitable means and is preferably composed of flexible material such as asbestos cloth 'or the like to render it conformable to the bearing surfaces 29 on the pallets. The casing elements 42-43 and the wind seal flap 44 thus form a wind sealed casing 52 enclosing those of the rollers 25 which extend along the side of the wind-box opening, with the wind seal flap situated above and outside of such rollers, that is, between the rollers and the outside atmosphere whereby the seal flap is protected from fouling by oil or oil vapor seeping or drawnfrom the bearings of the rollers and the-rollers and their bearings are shielded from dust.v

As a further refinement and closer approach to absolute perfection of the wind sealing, I provide a secondary wind sealed casing 53 enclosing and sealing of! the joints between the abutting end surfaces of the pallets. This secondary casing 53 is formed by a casing element 46 extending from the outer top edge of the casing 53 over the outer face of the side walls of the pallets to near the top edge of the side walls where a flexible seal strip 41 secured to the casing element 46 by rivets 48 seals the space between the casing element and th top. edge of the pallet walls. To improve the effectiveness of the seal the top edge ofthe side walls of the pallets are provided with straight flat sealing surfaces 49 for engagement by the sealing strip.

As indicated in Figs. 1 and 2, the wind sealed casings 52 and 53 extend along the entire length of the wind-box opening and are closed at the ends and sealed by end seals and 5| (Figs. 1, 6 and 7) As the construction of the end seals are identical a detailed disclosure of one will suflice, for example, the end seal 5|, at the discharge end of the machine, which end seal is shown more in detail in Figs. 6 and 7. The endseal is formed in separate upper and lower sections comprised of the upper and lower flat sided packing holders 54 and '55, each carrying assembled therein a packing element 56 and 5.1 respectively, composed of several layers of flexible heat resistant material, such as sheet asbestos. The holders are arranged to extend across the ends of the windsealed casings 52 and 53 and to hold the packing layers edgewise against the outer side surfaces of may be removed and replaced by two shorter pallets, one 12 inches and the other 15 inches, substituting a total length of 27 inches forthe 24 inches removed. This increases the total length of the train of abutting pallets by 3 inches which fills 3 inches of the gap at the at, the discharge end, thus shortening the gap by 3 inches.

Wind-sealing, that is the sealing of the machine against leakage of foul air into the wind-box is brought to a high degree of perfection in the the pallets. To hold the end seal in place across the end of the casings 52 and 53 and-against the pallets, I provide a pair of adjustable holding bolts 58 and 59 having their ends rotatably fitted in the socket elements 60 and it on the holders 54 and 55. through the stationary nuts 62 and 63 welded or otherwise secured to a bracket 64 fixed to the supporting framework of the machine.

From the above it will be seen that the use of seals located at the bottoms of the pallets as heretofore deemed necessary. in machines of this type, is entirely obviated thus avoiding decrease in efflciency of the seal due to wear and burring at the lower abutting ends of the pallets caused by the end drop. An additional advantage of applicants The threaded shanks of the bolts pass sealed casing 52 is that it also acts as a shielding encasement for the bearing rollers 25 along the wind-box opening. The placement of the sealing strip 44 above and between the rollers 25 and the outside atmosphere protects th sealing strip from seepage oil or oil vapor from the bearings of the rollers. As the portion of the flatly engaging abutting surfaces 65 of the pallets above the sealed casing 42 are not involved in the wear due to end drop and are subject to little or no wear otherwise, and remain in direct contact during passage of the pallets over the wind-box, the use of the upper sealed casing 53 is not absolutely necessary where such abutting surfaces are ground or machined, but is of great importance where these abutting surfaces are rough cast and unfinished. In either case the use of the upper sealed casing 53 is advisable because of the assistance it gives to the sealing effect of the lower casing 52. The importance of attaining the closest possible approach to complete sealing will be better appreciated when it is understood that an extremely large quantity of air must be handled to produce one ton of sinter. Any decrease of the effectivenes of the wind sealing of the machine permits foul air to enter the wind-box and this ineffectiveness is immediately reflected in decreased production and increased power consumption. Foul air in the sense here used means air entering the wind-box by any passage other than through the bed of material being sintered. Foul air in the wind-box lowers the temperature of the waste gas therein increasing the density. Since the exhaust fan has a fixed cubical capacity and speed, the power consumption is dependent upon the weight of the gas handled, and the weight of the gas is dependent upon its temperature. The waste gas delivered to the wind-box through the material being sintered'is at a temperature of approximately 350 F., while foul air enters the wind-box at atmospheric temperature.

While the invention is herein shown and described as embodied in a sintering machine, it will be obvious that the full combination and various of the subcombinations constituting the same are capable of other uses. For example that combination which constitutes the air-sealed conveyer system, is applicable to the treatment of substances by other than sintering or partial combustion, being useful as a conveyor wherever 'a substance is to be interposed between high and low pressure zones for treatment witha fluid or for filtering heating or drying operations, while the more simple subcombination constituting the conveyor system without the air seal is useful wherever a conveyor is required.

It is of special utility as a conveyor wherever the pallets or other conveyor elements are required to carry heavy' material at extreme temperatures, because of those features which reduce the cost of replacement of the conveyor elements necessitated by wear, and afford protection of the supporting bearings from extreme temperatures of the material handled.

While I have herein shown and described one specific embodiment of my invention for the sake of disclosure, it is to be understood that the invention is not limited to such specific embodiment but contemplates all such modifications and variants thereof as fall fairly within the scope of the appended claims.

What I claim is r 1. In a sintering machine, a wind box having an inlet opening, a stationary roller track-way having an up er section extending across the top of said opening and a lower return section extending back below the opening, and a plurality of pallets arranged to travel along said track-way, each pallet having on each side a pair of bearing surface portions, one a downwardly facing portion for engagement with the rollers of the upper track section in an upright position of the pallets and the other an upwardly facing portion for engagement with the rollers of the lower track in inverted position of the pallets, and in which the rollers of the upper section and the downwardly facing bearing surface portions of the pallets are inclined inwardly and downwardly-of the pallets in the upright position of the pallets.

2. In a sintering machine, a wind box having an inlet opening, a stationary roller track-way having an upper section extending across the top of said opening and a lower return section extending back below the opening, and a plurality of pallets arranged to travel along said trackway, each pallet having on each side a pair of bearing surface portions, one a downwardly facing portion for engagement with the rollers of the upper track section in an upright position of the pallets and the other an upwardly facing portion for engagement with the rollers of the lower track in inverted position of the pallets, and in which the downwardly facing bearing surface portions of the pallets are inclined inwardly and downwardly of the pallet in the upright position of the pallet and the upwardly facing bearing surface portions of the pallets are inclined inwardly and downwardly of the pallet in the inverted position of the pallet.

3. In a sintering machine, a wind box having an inlet opening, a stationary roller track-way.

having an upper section extending across the top of said opening and a lower return section ex-' tending back below the, opening, and a plurality of pallets arranged to travel along said trackway, each pallet having on each side a pair of bearing surface portions, one a downwardly facing portion for engagement with the rollers of the upper track section in an upright position of the pallets and the other an upwardly facing portion for engagement with the rollers of the lower track in inverted position of the pallets, and in which the rollers of the upper section and the downwardly facing bearing surface portion of the pallets are inclined inwardly and downwardly of the pallet in the upright position of the pallet and the rollers of the lower section and the upwardly facing bearing surface portions of the pallets are inclinedjnwardly and downwardly of thewpallet in the inverted position of the pallet.

4. In a sintering machine, a train of wheelless pallets, a driving rack formed in each pallet, a gear wheel for driving the train of pallets by engagement with the rack, laterally extending bearing flanges carried by said pallets, and upper and lower roller track-ways engaged by said flanges for guiding said pallets over and around the top of a wind box.

5. In a sintering machine, wheelless pallet having a side wall thickened at the bottom to contain a rack section countersunk in the bottom end face of the side wall, and a bearing ledge projecting laterally outwardly from each side and extending along each side wall the full length of the pallet for engagement with a roller track-way.

6. In a sintering machine, a stationary roller track-way having upper and lower sections contrack-way.

bear on the rollers of the upper and lower roller track sections respectively, and a third bearing surface arcuate in form, arranged to bear on the said curved sections of the roller track-way.

7. In a sintering machine, a stationary roller track-way having upper and lower sections connected by a curved section for guiding a train of pallets over, and around under a wind box opening, and a train of pallets each having oppositely facing bearing surfaces arranged to bear on the rollers of the track sections in the top and bottom positions of the pallets, respectively, and curved bearing surfaces arranged to bear on the rollers of the said curved sections of the roller 8. A sintering machine as claimed in claim 7 in which the bearing flanges are near the bottom of the pallets, and act as strengthening ribs extending the length of the pallet.

9. A machine for sintering and roasting ore or other metal bearin'g material comprising a wind box having an inlet opening, a series of stationary roller supports arranged to form a roller trackwayacross the top of the wind box inlet opening, a plurality of separate wheelless ore-carrying pallets arranged to be moved in a train in abutting relation with each other over said opening along said rollertrack-way, and a cooling pipe extending along the series of roller supports in heat interchange relation thereto.

10. In a sintering machine, a wind box having an intake opening, and a train of abutting pallets arranged to pass over said opening end-to-end,

roller supports for said pallet, and a wind sealed casing extending around the joint between the pallets and the side of the wind-box opening and outside of. said roller support.

11. A sintering machine comprising in combination a wind box having an intake opening, a train of pallets, means for moving said train of pallets along over said opening end-to-end in abutting relation,'said pallets having side walls extendingaway from saidinlet opening, the side walls of adjacent pallets abutting end-to-end, roller supporting means between said pallet and said wind box, and a wind-sealed compartment extending the length of the wind box along the sides'of the opening and the outside of the side walls of the pallets, enclosing the roller supports, the outside of the joints between the pallets and the wind box, and substantially the entire outside of the joints between the side walls of adjacent pallets within the length of the compartment. I s

12. In a machine for sintering and roasting ore 'or other metal bearing material, a wind box having a top opening, a train of pallets arranged to slide over the top opening of the wind box, said pallets having side walls abutting end-to-end to form a substantially continuous side wall for the train, and a casing extending from around the sides of the top opening of the wind box to near the top of the sides of the pallets to partition from the outside atmosphere the joints between the pallets and the wind box, and a wind seal between the top portion of the casing and the top portion of the sides of the pallets.

13. A machine for sintering metal bearing material comprising a wind box having an open top, a stationary-roller track-way extending over and around under the top of the wind box, a train of Wheelless pallets arranged to move along the roller track-way over the open top of the wind box in upright position and back around under the top of the wind box in inverted position as an endless train, said pallets each having downwardly facing straight bearing surfaces extending along the pallet in the direction of travel and arranged to engage the rollers extending over the top of' the wind box with the pallets in an upright position, and upwardly facing straight bearing surfaces extending the length of the pallet in the direction of travel and arranged to engage the rollers extending below the top of the wind box with the pallets in an inverted position, and a wind seal extending around the joint between the pallets and the wind box opening, from the side of the wind box below the opening into sliding, wind-sealing contact with the said upwardly facing bearing surfaces.

14. A sintering machine comprising a wind box having an inlet opening, a track-way having an upper feeding section and a lower return section for guiding a train of pallets over said opening along the upper section and back along the lower section, a toothed drive connection carried by connections for driving the pallets, the pitch of said toothed drive connection and driving element being several times less than the length of a pallet and a submultiple of the length of the pallet, the greaterportion of said pallets being of a given standard length equal to a multiple of the pitch of saidltoothed drive connection and a lesser portion of a length shorter than the said standard but equal to a multiple of said pitch.

15. In a sintering machine, upper and lower track-ways connected by an arcuate section of roller track-way to form a loop for guiding a train. of grate pallets through a sintering zone and back below the sintering zone in inverted position, a train of grate pallets, e'ach pallet having an arcuate bearing surface arranged to bear upon the rollers of the said arcuate section of track-way.

16. In a device for conveying material, wheelless carrier having a side wall thickened at the bottom to contain a rack section countersunk in the bottom face of the wall and a bearing ledge projecting laterally outwardly from each side wall and extending there along substantially the full length of the carrier for engagement with a roller track-way.

1'7. In combination, a roller track-way having a substantially straight section and an arcuate section, and a conveyor element arranged to be guided by said track-way having a straight bearing-surface portion arranged to bear upon said straight section and an arcuate bearing portion arranged to bear upon said arcuate section.

18. A machine for sintering or treating metalbearing material, comprising a wind box having

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