US2985440A - Pallet construction for sintering apparatus - Google Patents

Description

2 Sheets-Shea?l 1 BYM,M-/

May 23, 1951 v. F. KooNTz PALLET CONSTRUCTION FOR SINTERING APPARATUS Filed June 6, 1958 May 23, 1961 v. F. KooNTz 2,985,440

PALLET CONSTRUCTION FOR SINTERING APPARATUS Filed June 6, 1958 2 Sheets-Shea?l 2 .sa uw Rm SR m L Q w L m\ l Il mE 8N K. m x ,mm 1%. L @y m .Inl 'lll I I l l I I Illl/ Ill l l l l I l l llll V 9%@ f E. L

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United States Patent O PALLET CONSTRUCTION FOR SINTERING APPARATUS Victor F. Koontz, Moon Township, Allegheny County, Pa., assigner to Dravo Corporation, Pittsburgh, Pa., a corporation'of Pennsylvaniav Filed June s, 195s, ser. No. 740,317

2 claims. (ci. zas- 21) This invention relates to sintering apparatus and is for an improved pallet or tray construction for use in down draft sintering apparatus.

In down draft sintering apparatus, the pellets to be burned or sintered are deposited on a succession of traveling trays or pallets that Imove progressively over a succession of suction chambers, or wind boxes, so that the charge, after being ignited, is supplied with air drawn down through the charge. These trays or pallets are in reality each a small car rolling or sliding on rails at each end ofthe pallets, each car abutting against the one ahead to form in effect, a continuous traveling support. They are rectangular in shape with their greatest :length crosswise of the direction of travel. They have strength members extending in the direction of their length, whichv members are anged at the top. A system of grate bars extending crosswise of the length of the pallet are intertted with these llanged members to support the charge which is to be burned.

In a typical operation, the top ilange of the supporting or strength bars may reach a temperature of 1500 to 1900 F. while the 'bottom flanges of the same members are more nearly that f of the combustion gases Vin ythe neighborhood of l1'00to-l300 -F.

Warping of the trayswhas been a constant problem, since after a period of use they sag from the ends toward the center. Various eforts have been made to correct this without success, although it has been a persistent and costly weakness. Among other things, it has been proposed to use more massive strength members. It has also been proposed to use alloys for the strength members. A further unsuccessful expedient has been to provide air chambers in the strength members to lower the temperature of the critical-ly stressed metal.

Since sagging could not be corrected, one expedient is to make them reversible and allow them to sag in one direction, turn them over, and let them sag in the other direction. Another plan is to make them in two sections and bolt them together at the middle. When sagging occurs, the bolts are loosened and shims are used between the sections to try to correct warping.

I have determined that sagging is not due merely to the overheating of a beam section while under uniform load, but that by reason of the non-linear temperature differential that exists at the top and the bottom of the beam a high stress is induced in the ilange at the top which supports the grate bars as it attempts to expand under the greater heat and this expansion is restrained by the cooler metal at the bottom of the section. This results in compressive forces in the top ilange sufficient to upset or warp it, so that when the pallet cools to a point where the top and bottom ilange are at equal ambient temperature, the top is shorter than the bottom, resulting in a downward curve from the ends toward the middle.

'My invention has for its principal object to provide a pallet construction in which thermal stresses such as produce warping will be avoided. A further object of Patented May 23, 1961 my invention is to provide a construction in which the beams will be subjected to more nearly uniform temperature at the top and bottom. A still further object is to provide a pallet of improved construction.

vThese and other objects and advantages will be apparent to rthose skilled in the art from the following description of my invention in conjunction with the accompanying drawings, in which:

Fig. 1 isa front elevation of one end of a pallet embodying my invention, it being understood that the opposite end is a counterpart thereof, and for clarity of illustration only one end has been shown;

Fig. 2 is a fragmentary transverse vertical section in the plane of line yII---II of Fig. 1 with the grate bars indicated by dot-and-dash lines;

Fig. 3 is afragmentary top plan view of an area of,

the pallet showing my invention; and

Fig. 4 is a' longitudinal vertical section in the plane of line IV--IV of Fig. 3.

Referring to the'drawings, the pallet comprises a carriage which is essentially abeam of rectangular section.

YThe arrow inFig. 2 indicates the direction of travel of the pallet. At each end of the carriage there is a transition plate 2 to which is secured a casting 3 that carries the shaft for supporting the wheels 4 that support the pallet on the track (not shown) along which the pallet moves, the transition plate abutting against an end plate 2a. Y There' is a side plate 5 on this casting to retain the bed of material on the pallet, and 6 designates the usual seal that rides along the top of the wind boxes.

- I have shown the carriage as being fabricated fromy p tion not onlyat the ends by the end plates 2, but at intervals along the length ofthepallet by cross` members of I-beam section, designated 9 in Figs. 3 and 4. The number of I-beams 8 and the number of cross connections 9 depends upon the size of the sinteng apparatus and is not material to the present invention, but there should be a maximum open area through which combustion gases can be drawn, and it Iwill of course be apparent that this structure could be an integral casting.

Thus the carriage comprises a composite beam of rectangular section formed of parallel sections connected at their ends and intermediate points. Bolted to the top of this composite frame are a plurality of parallel angle sections 10, the bolts for securing them being designated 11. The vertical webs 10a of these angles have horizontally elongated slots 12 therethrough. Placed against and bolted to each of these vertical webs 11a of the angles are the vertical webs of composite flanged bars 13 and 14, the bars 13 being at the longitudinal side edges of the structure and having a horizontal ilange 13a that extends toward the longitudinal center of the structure, while the bars 14 have flanges 14a that extend in both directions. The flanges 13araud 14a fit into' notches in the ends of the replaceable grate bars 15 that extend in a direction transverse to the length of the pallet, and in this manner support and retain the grate bars in the structure. The llanged bars 13 and 14 are secured to the Vertical webs 11a of the angles by bolts 16 passing through the bars Iand through the slots v12 in the vertical webs, with nuts L16a that are taken -up firmly but not too tight. This provides a friction clamp connecting ythe anged bars and the angles. v

From the foregoing it will be seen that the grate. bars,T

and 14 are separate from the bottom beam sections 7 'and'z 8 respectively, forming rigid beams in which the top` can' expand and contract independently of the bottom by reaso'n of the bolts 16 passing through horizontally slotted openings in one part of the composite structure. The ends of the top bar portions 13. and 14 are not confined, so that expansion and'contraction of these portions relatively to the supporting structure below is confined only by the tightness of the bolts and nuts 16-f-16a..v

Also there areV two boltedvconnections, one. between the bars 13 and 14, and the vertical `wehstof the angles 11, and the second between the bases of the angles 11 and the tops of the main pallet frame. Since these afford al poor path of heat conductivity, there istless heat carried by conduction into the top parts of the channels7 and beams 8, and they thereforeare at a more nearly uniform temperature during the sintering of the charge on `the grates, this beingV closerto thetemperature of the combustion gases. a -v By reason of this construction, therefore, a pallet'is provided in which sagging and cracking is greatly reduced or entirely eliminated, thereby getting ridV of one o'f the heretofore troublesome problems encountered in apparatus of this kind. Y Y

I claim: Y

l. A pallet -for sintering machines comprising a rigid frame having like top and bottom surfaces so that either may be used by turning it. over, the frame being of rectangular` transverse section and having two end members-v with spaced parallel beams connecting the end members, the spaces between thel beamsI being open for thetpassage of air through the pallet, the uppermost surface of the frame having a plurality of angleA bars releasably secured thereto with one leg of each bar supported on the uppermost surface ofy the frame and having -one'leg'portionextending vertically,a flanged grate-supportingl bar having a- Vertical web portion bolted to the vertical legl portion'of each of saidangle bars by bolts passingthroughthe respective vertical legportions of the grate-supporting"4 bar and theV anglev bar, one of the leg portionsso' boltedtogether being longitudinally Vslotted for the passagev of bolts therethrough but allowing relative expansion and contraction of one leg portion lengthwise, to', the other, and grates having grooved ends intertted with the flanges of the grate-supporting bars, said anges and grates being in a plane spaced above the uppermost surface of the rigid frame.

2. A pallet for sintering machines comprising a main supporting frame having like top and bottom surfaces sd that it may be reversed, said frame having spaced parallel beams extending longitudinally of the pallet and joined at their ends by end` plates, said frame heingopenV for the passage of gases or air therethrough; parallel flanged grate-supporting structural assemblies removably secured to the tops of said beams and resting thereon with their ends clear of the end plates of the main frame, each said assembly having one longitudinally-extending structural lower sectio'n resting on and secured to the beam along which it extends Vby a bolted connection, each said assembly having a longitudinally-extending upper structural section witha horizontal ange: at the top thereof and secured to the lower section below the anged top by a bolted connection, the upper member o'f each said assembly being thereby connected with the beam along which it extends through anV intervening structural section and through bolted connectionsat two levels,'the bolted connections at one level having longitudinally-elongated bolt holes to enable the upper section to expand and contract lengthwise relative to the beam along which it extends, and transverse grates extending crosswise of the pallets between the flanged uppersections of theassemblies,` the grates having bifurcated ends engaging the flanges of the upper sections, the gratebars being elongated by the grate-supporting assemblies entirely above the top of the main supporting frame.

References Cited in the le ofthis patent UNITED STATES PATENTS t 1,098,035 -Greenwalt May 26, 1914 2,434,852 Jackson Jan. 20, 1948 2,834,593 Hudson May 13, 1958 FOREIGN PATENT-,s

60,1162 Sweden Nov. 23, 1922 719,998 Great Britain Dec. 8, 1954 NITED STATES PATENT OFFICE CERTIFICATE OF COBBECTIQN Patent Noe 2,985,440 May 23, 1961 Victor E. Koontz 1t s hereby certified that error' appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

une 56 and lines 66 and 6T, for "-'vertical each occurrence, read vertical webs 10a --3 line 15, for "11", both occurrences, read 10 Column 2, webs 11a", column 3, column 4,

Signed and sealed this 7th day of July 1964.,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents lines 31 and 32, for "elongated" read elevated

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