US2764403A

US2764403A - Pallets and grate bar therefor

Info

Publication number: US2764403A
Application number: US463678A
Authority: US
Inventors: William M Duncan
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-10-21
Filing date: 1954-10-21
Publication date: 1956-09-25
Anticipated expiration: 1973-09-25

Description

P 1956 w. M. DUNCAN PALLETS AND GRATE BAR THEREFOR 2 Sheets-Sheet 1 Filed 001.. 21, 1954 M N R a mu N 8 v M "W 5: 7 u 3 M \5 W W b .3 Y B 9 )5 3 A TTORNEYS Sept. 25, 1956 w. M. DUNCAN 2,764,403

PALLETS AND GRATE BAR THEREFOR Filed Oct. 21, 1954 2 Sheets-Sheet 2 FIG. 3.

45 47 23 4 f 43 k z 23 FIG .4.

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V F W 37 35 I27 INVENTOR, WILLIAM M. DUNCAN w meegflww ATTORNEYS United States Patent This invention relates to the pallets of a sintering machine or related apparatus, and more particularly to the construction and attachment of the grate bars of such pallets.

It will be understood that in the heat treatment of ore and other material, it is customary to utilize a machine having a series of pallets entrained upon an endless track. The material to be sintered or otherwise treated is fed onto the pallets as they move from one end of the machine and is heated as the pallets move toward the other end, where the material is automatically dumped. Each pallet has a grate-like bottom formed by elongated grate bars seated at their ends on a pair of transverse frame members, which bridge the space between the sides of the pallet. Since the grate bars deteriorate in use, they are usually replaceable. Accordingly, it has been customary to form grooves along the transverse frame members, the grate bars being individually inserted therein or withdrawn therefrom from one side of a pallet.

This type of pallet is not entirely satisfactory, however, because the retaining grooves become clogged and the grate bars warp, with the result that difficulty is experienced in sliding the bars within the grooves. Also, it is not uncommon to find that it is necessary to remove nearly all of the bars in order to replace only a few defective ones. It is therefor an object of this invention to provide an improved arrangement for securing the grate bars on a pallet, and especially, to provide for individual replacement of selected bars without disarrangement of the others.

In addition, it is to be observed that these pallets typically are from six to twelve feet in width and two feet in length. The grate bars accordingly are two feet long and perhaps an inch wide, and as such are subject to warpping. The elongation under heat is not particularly troublesome, but the lateral deflection of the bars gives rise to operating difliculties. One of the objects of this invention, therefore, is to provide a pallet wherein such deflection or curling of the grate bars is substantially eliminated, or at least, is so slight as not to interfere with the operation of the machine or the attaching means for the grate bars.

Briefly, these objectives are achieved by forming the grate bars with depending ears, each ear being shaped to embrace a holding rod that extends transversely beneath the bars between the sides of the pallet. Preferably, the holding rods are of non-circular cross section, and the depending portions of the grate bars are formed with upwardly extending slots of key-hole shape. The narrow base of each slot is of a width slightly greater than the narrow dimension and less than the wide dimension of a holding rod. With this arrangement, any grate bar may be readily removed or inserted, upon rotation of the holding rod so that the thin section thereof is aligned with a narrow part of the key-hole slot. The grate bars are simultaneously locked in position by rotating the rod to a position such that the thick section thereof lies across the narrow base of the several slots,

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the rod then being secured against rotation, as by clamps affixed to the pallet at its sides.

In order to minimize heat-produced deflection of the grate bars, the pallet is formed with at least three, and preferably four transverse frame members in spaced relationship from one another. The grate bars, then are of a reduced length, such as to bridge only two of the transverse frame members.

Other features of the invention will be in part apparent from and in part pointed out in the following detail description taken in connection with the accompanying drawings, in which:

Fig. 1 is a transverse section taken on the line 1-1 of Fig. 2, showing a pallet embodying features of this invention;

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is a section taken on the line 33 of Fig. l; and

Fig. 4 is a sectional View similar to that of Fig. 2 but illustrating an alternative embodiment of the invention.

Referring now to the drawings, there is shown a pallet having the usual side walls 1 and an open frame formed by

members

3 and 5. The frame portions 5 define the sides of the pallet, whereas the transverse frame members 3 bridge the space between the sides at the ends of the pallet. These transverse members 3 may be reinforced by a web 7 extending therebetween intermediate the sides of the pallet, and there may be additional transverse frame members 9 extending parallel to and between the end-forming members 3. Rollers 11 are journalled on the sides 5 of the pallet for cooperation with track-forming rails 13, although the track could be formed of rollers on which the sides 5 of the pallet would ride.

It will be understood that sprockets are generally provided at the forward end of the machine to lift the pallets from a lower reach of track to an upper track where they are loaded with the material to be heated and admixed fuel. The pallets are moved along the upper track in abutting relationship with one another, so as to form a continuous trough, a draft being induced through wind boxes beneath the pallets to control burning of the fuel. When pallets individually reach the end of the upper track, they roll down a reverse bend, thereby dumping their contents, and along the lower reach of track to collect adjacent the sprockets. Such a machine is shown, for example, in my Patent No. 2,519,179.

In accordance with previous practice, the frame elements 3 extending across the pallet were formed with grooves in which the grate bars were seated. These retaining grooves, in turn, had slots at their ends or at one side of the pallet so that the grate bars could be individually withdrawn and inserted therein; but it will be apparent that this practice is somewhat slow and diflicult. Although only a few of the bars might need replacement, it was generally necessary to remove a considerable number of other bars before the defective ones could be moved to the slots at the side of the pallet. Furthermore, warping of the grate bars and clogging of the retaining grooves interfered seriously with the replacement of the grate bars.

These difliculties are herein avoided by securing the grate bars independently of the transverse frame members. In particular, the pallet carries a plurality of standard grate bars 15, a pair of side bars 17 and certain center bars 19. Each of these grate bars is formed with an elongate body which bridges and rests upon the

transverse frame members

3 and 9, and which may have side bosses 23, the lateral spacing thus achieved providing the draft passages in the grate or bottom of the pallet. The grate bars are then secured against displacement from the pallet by means of a holding rod 25, which extends transversely beneath the grate bars between the frame members 9 through an opening 26 in the Web 7.

3 This rod 25 in turn is secured at its ends to the sides 5 of the pallet, and each grate bar has a cooperating part depending from the body in embracing relationship with the holding rod.

Each of the so-called standard bars has an ear 27 depending from its elongate body 21 at a point between the frame members 9, which ear may be of a width equal to that of the body. The center bars 19 have a relatively wider body 31 so that the associated ears 29 may be offset to one side, thereby permitting the body portions 31 to overlap the center web 7. These

ears

27 and 29, in turn, are formed with slots 33 of key-hole outline, the mouth 35 of a slot being narrower than the generally circular inner head portion 37.

The key-hole slot 33 is designed for use with a holding rod of such non-circular cross-sectional shape as to clear the mouth of the slot when in one position and to lock over the mouth of the slot when the holding rod is rotated within the head 37 to a second position. For example, the holding rod may be a length of square stock, which is readily rotated by a conventional wrench, and which may be locked against rotation, as by a clamp 39.

Referring to Figs. 1 and 3, the body 41 of a side grate 17 is cut away at 43 to accommodate the clamp 39 opposite the holding rod. A part 45 of the clamp is secured within the recess 43 by the head 47 of a bolt (the bolt having an outer nut 49), so that a leg 51 projects downwardly through the grate bar 17. The end of the leg 51 is notched at 53, as shown in Fig. 3, for locking cooperation with the end of the holding rod, which is otherwise held within a loop-forming section 55 depending from the body 41 of the grate bar.

When the clamp 39 is secured in position, the holding rod 25 is secured against rotation in locking relationship with respect to the key-hole slots 33 in the other grate bars 15 and 19. Upon removal of the clamp 47, the holding rod 25 may be rotated to a position such that the narrow dimension thereof is aligned with the narrow mouth 35 of the key-hole slot, and any of the grate bars 15 and 19 may be readily lifted from the pallet without displacement of the others. The holding rod 25 is held at its ends by the side bars 17 and by the web 7, so that it does not drop from the pallet when rotated to its unlocking position. The rod may be removed, however, by lifting all of the grate bars, including the two side bars 17.

In Figs. 1-3, the grate bars are shown to extend the full length of the pallet, which is normally two feet, this being a conventional practice. Grate bars of such length sometimes curl under heat, however, and for that reason, the invention also contemplates a construction of the type disclosed in Fig. 4. It has been found that the tendency to curl is greatly reduced, if not prevented, by reducing the length of the bars, so that a given bar bridges only two of the

transverse frame members

3 and 9. In that event, each bar is provided with a locking ear 127 for cooperation with holding rods 125. The body portions 121 of the bars are in substantial abutting relationship at their ends 157, the construction otherwise being the same as that described previously.

From the foregoing description, it is apparent that those skilled in the art will understand the structure, function and mode of operation of the invention herein disclosed, and appreciate the advantages thereof. Although several embodiments have been disclosed in detail, it is to be understood that the invention is not limited thereto, but the drawings and description thereof are to be understood as being merely illustrative. It is realized that many modifications and variations will present themselves to those skilled in the art without departing from the spirit of this invention or the scope thereof as set forth in the appended claim.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

In a pallet of the type described having sides, trans- 'verse frame elements extending between said sides, and a plurality of grate bars supported on said transverse frame members; the improvement comprising a holding rod extending transversely beneath said grate bars, said holding rod being releasably secured to said pallet and being of non-circular cross section, each of said grate bars being formed with an upwardly-extending slot of key-hole outline, the narrow mouth :of which is sufiicient to clear the holding rod in one position and to lock with the holding rod when the rod is rotated to a second position within the relatively wide head portion of the keyhole slot, a clamp secured at the side of said pallet for locking said holding rod against rotation when in its position of interlocking relationship with respect to the key-hole slots of the several grate bars, one of the sidemost grate bars being recessed to accommodate said clamp, and said clamp having a leg projecting through Hegeler et a1 Nov. 22, 1932 Clawson May 23, 1933