US2872174A - Roller furnace construction and method of maintenance operation - Google Patents

Description

Feb. 3, 1959 E. w. LINDQUIST ROLLER FURNACE CONSTRUCTION AND METHOD OF MAINTENANCE OPERATION Filed Jan. 8, 1954 4 Sheets-Sheet l a D o a o o l(||| E. W. LINDQUIST ROLLER FURNACE CONSTRUCTION AND Filed Jan. 8, 1954 4 Sheets-Sheet 2 :Fig. 3.

INVENTOR ELMER W. LINDQUIST Feb. 3, 1959 Efw. OLINDQUIIST ROLLER FURNACE CONSTRUCTION AND METHOD OF MAINTENANCE OPERATION Filed Jan. 8, 1954 4 Sheets-Sheet 3 INVENTOR} ELMER W LINDQUIST Feb. 3, 1959 E. w. {.INDQUIST 2,872,174

ROLLER FURNACE CONSTRUCTION AND METHOD OF MAINTENANCE OPERATION Filed Jan. 8, 1954 4 Sheets-Sheet 4 INVENTOR ELMER W. LINDQUIST United Sttes Patent f ROLLER FURNACE CONSTRUCTION AND METHOD OF MAINTENAN OPERATION Elmer W. Lindquist, Montgomery Township, Montgomery County, Pa., assignor to Drever Company, Bethayres, Pa., a corporation of Pennsylvania This invention relates to a new furnace construction employing a roller hearth and to a method of maintaining such furnace. More particularly, this invention pertains to a new furnace providing novel roller installation and mounting means and to a new method of installing, removing, and changing rolls in such a furnace.

Roller hearth furnaces are Widely known and used in the metallurgical and other industries for a host of purposes. In such furnaces, a hearth or conveying bedis provided by a plurality of transversely extending parallel rollers, the axes of which are usually horizontal or at least in a common plane. In high temperature furnace service, such rollers are usually driven and the driving means as well as the bearing means for the rollers are frequently located outside the side walls of such furnaces, which side walls extend between the floor and roof thereof. In many operations, doors are provided at the ends of the furnace above the hearth or bed so that the furnace can be substantially totally enclosed during the periods between entry and discharge of the workpieces going through the furnace. With the furnace hearth or bed above floor level, the installation of rollers and any occurrence necessitating the removal of a roller or the replacement of a roller have not been readily conductible. In the case particularly of larger furnaces, it has generally been considered necessary when any suchjoccur- 2,872,174 Patented Feb. 3, 3959 Figure 6 is a view looking at the outer end of a new wall block as shown in Figure 5;

Figure 7 is a perspective view looking toward an inner end of a lower. section of a port block;

Figure 8 is a perspective view looking toward an outer side of the lower section of the port block shown in Figure 7; I

Figure 9 is a perspective view looking at an inner end of the upper section of a port block; t

Figure 10 is a perspective view in section, showing a new port block and a new wall block forming an embrasure closure Wall member in that practice of this invention illustrated in the foregoing figures;

Figure ll is a view of a new wall block similar to that shown in Figure 5 with the addition of a tunnel recess to enable it to be used as a burner block for underhearth rence took place, to cool the furnace downbefore enheight of the roller, or by disengaging the roller to be removed from the furnace structure and taking it'out above its normal operative position. Even in cases of smaller furnaces, when a roller change might be attempted without lengthy cooling down, there was'nevertheless a material downtime with its attendant loss of production in addition to relatively difficult acts involved in removing the rollers while in a position at or above the hearth level.

In the new construction and process of this invention, the foregoing difficulties have been overcome. Other objects and advantages will be apparent from the following description and from the accompanying drawings, which are illustrative only, in which Figure l is a side view of a portion of a length of a new furnace embodying my invention and in which one-of the roller embrasures has been uncovered;

Figure 2 is a longitudinal view of the new structure shown in Figure 1 taken along line II--II of Figure 1;

Figure 3 is a longitudinal view taken along line IIIIII of Figure 1;

Figure 4 is a view similar to the view shown in Figure 3, illustrating a roller in the process of being removed in accordance with my new maintenance operation;

Figure 5 is a perspective view, of a new wall block which may be utilized in one practice of my invention;

floor 14 is preferably a refractory aggregate.

Figure 12 is a view in side elevation from the other side of the furnace shown in Figure l; and

Figure 13 is a perspective View of a skid platform suitable for use in the illustrated practice of this inventron.

Referring to the drawings, a new furnace 10 is provided which constitutes a practice of my invention. In that furnace, a shell is provided comprising a bottom steel plate 11 and side steel plates 12. These-plates are secured to vertical buckstays 13 in spaced arrangement along the two sides of furnace 10. Plate 11 which may also be transversely supported on the underside thereof may be filled with a refractory concrete mixture to provide a floor 14- inside the furnace. The level 1100,1114 may be the same as the level of outside floor15 in a plant in which furnace It? is constructed. Floor 15 may be considered the grade or ground level of furnace 10. The binding structure of furnace 10 may include transverse I-beams 16 secured to the upper'parts of buckstays 13, longitudinal primary channels 17 and longitudinal secondary channels 18 to tie the structure together at the top. Stifliening channels 19 may also be used between buckstays to assist in rigidifying the furnace steel work. A longitudinal channel 24 may extend between buckstays 13 at grade level, the channel 20 being affixed to shell 12 and forming with I-beam jackstay 21 which is secured thereto and to shell 12, an inverted T surrounding two sides of the two embrasures 22 in each of the bays 23 in furnace ltlbetween adjoining buckstays 13. Various other buckstay and binding structures may be employed with a practice of this invention incorporated therewith. Furnace 10 may be lined with refractory. In the illustrated furnace embodiment, which may serve as a roller hearth annealing furnace for steel sheets and plates, In addi tion, a refractory roof 24 may be suspended from the top steel binding structure as illustrated, or an arched refractory structure might be employed utilizing keystone and skew brick arrangements as will be understood by those in the furnace art. Side walls 25 in addition to constituting sheet 12 on the outer sides thereof respectively may comprise pillars 26 of firebrick between embrasures 22, the tops of pillars 26 being provided with alternately facing skew bricks 27 for brick arches 28 spanning the top of the embrasures 22. Firebrick courses 29 rise above the skew and arch bricks 27 and 28 as shown in Figure 2 to meet the underside 30 of roof 24- and complete the refractory enclosure on the inside of the furnace shell. The brick courses 29 may be inter rupted by refractory framed windows 31 constituting peepholes at spaced locations along the furnace, by

36 the axes 37 of which lie in a horizontal plane. As"

shown, the rollers 36 are provided with. refractory bodies but such rollers may be made of other materials including metal and all-metal constructions. The center lines 37 of rollers 36 are spaced to conform to the spacing of the embrasures 22 and bays 23 there being two rollers 36 in each bay in the illustrated embodiment. Ends 38 of rollers 36 are of reduced diameter and extend from the insideof furnace to the outside thereof through ports 39. Assuming work proceeds in the direction of arrow 40 through furnace 10, right-hand end 38 of each roller 37 may be provided with an adjustment mechanism 41 to keep the refractory body of roller 36 under compression. The adjustment mechanism 41 may include temperedsprings for such compression purpose. Each roller 36 is supported by its ends 38 outside the side walls 25 and shell 12 of furnace 10 to avoid interference, at thehigh temperatures usually prevailing in the furnace 10, with the functioning of the bearings supporting the rollers 36. Pillow .blocks 42 having bases 43 may be employed for such support. However, the bases 43 of bearings 42 may be securely bolted to a horizontal flange 44 of an angle. bracket 45. Brackets 45'may have a length to precisely span the distance between a buckstay 13 and the outer flange of jackstay 21 adjacent the top thereof, the brackets 45 being bolted to the respective stays. In this way, rollers 36 may be suspendibly mounted in the upper part of embrasures 22 from the structural metal members, usually steel, of the furnace 10. Hence, any roller 36 may readily be released from its support by unbolting the pillow blocks 42 from the brackets 45, or as readily installed by connecting the bearings 42 to such brackets. It will also be noted that in the embodiment shown, the inner flange of jackstays 21 is bolted to the lower part of the upper portion of plate 12, the plates 12 on the sides being cut out in each bay between the sides of embrasures 22 nearer the adjacent buckstays 13 and between the tops and bottom of such embrasures. As shown in'Figure 1, such cutting preferably conforms at the top of the embrasures to the arch shape of the brick arches 28. I

A roller drive chain 46 may be operative on the left side of the illustrated furnace 10 in an endless chain fashion, as will be understood by those skilled in the furnace roller driving art. Thus, chain 46 may engage a sprocket 47 fastened to the nearer end 38 of each roller 36 in a. horizontal upper reach of such chain 46. Disengagement of the chain may be guarded against by a hold-down angle 48 fastened to a fabricated boss 49 secured as by welding to each of the brackets 45 on the left-hand side of furnace 10. At the ends of the furnace 10, chain 46 may have vertical reaches and lower guide sprockets 50 for the lower return reach 51. Guide sprockets 50 may be rotatably attached to the bottom of the nearest inverted T-member 21. A driving pinion may engage chain 46 along reach 51 to rotate rollers 36 in a direction to -advance the work in accordance with travel arrow 40. p 2 f Ports 39 may be closed by a port block 52 which as shown is divided into an upper section 53 and a lower section 54 along a horizontal'line 55 passing through axis 37 at the operative height of thelrollers 36 in the illustrated furnace 10. Because of the shape of the ends 38 of the illustrated rollers 36, port block 52 is conically recessed at 56 on the interface thereof while cylindrical opening 57 also formed by the two sections Ofblock .52

permits the reduced end of end 38 of the rollers 36 to pass from the inside of furnace 10 to the outside there of. A metal shell 58 having inwardly extending flanges as shown in Figures 8 and 9 is completed with the addition of a suitable castable refractory shape mounted therewith to provide the composite shape shown in such figures. The uppermost inwardly extending flange on facingSS is arched with the associated refractory to conform to the arched top of embrasure 22, or both the top of embrasure 22 and the top of port block 52 may be made straight. The upper section of shell 58 is provided with a flange 59 which is bolted to plate 12 above the opening in that plate extending between channel '20 and the top of embrasure 22. Similarly, the metal facing 58 is provided with side flanges 60 for bolting along the sides of embrasure 22 to hold each of the sections 53 and 54 in place.

Although shown horizontally divided, :1 port block 52 maybe vertically or otherwise parted for ease of installation'and removal as occasion requires. Indeed, in the illustratedembodiment, upper section 53 of port'block 52 ne ed not be removed nor is it necessary to remove the brackets 45 extending across the outside of such upper sections 53 in' installing or removing roller 36. A wall block 61 with a port block 52 constitutes a closure member for an embrasure 22; Such a wall block may be of generally cubicalsection with an integral saddle crest 62 across the top thereof inwardly of the outside of such block 61. The outside of block 61 is provided with a metal plate shell or facing 63 having inwardly extending flanges 64, a horizontal outwardly extending flange 65 and side flanges 66. Thus, facing 63 forms a cup on the inner side thereof into which a refractory 67 may be cast to form block 61 inclusive of saddle crest 62, the refractory 67- being suitable for the furnace service to be incurred. Flanges 66 are also bolted or otherwise removably fastened in the same manner as the removable fastening of port block 52 to the sides of the embrasure 22 in which such wall block 61 is placed. Flange 65 fits on top of channel 20 and with a stiffening angle 68, each wall block 61 may readily be moved inwardly and outwardly as occasion requires. Some wall blocks 61 may be provided with central openings 69, as shown in Figure 7, to act as burner tunnels. Thus in the illustrated embodiment of furnace 10, alternate wall blocks 61 on each side are provided with such tunnels 69, the burner tunnel blocks 61 of which in each-bay are also staggered. Thus, since the axis 70 of each block 61 having a tunnel 69 therein is parallel to axis 37 and beneath the same, furnace 10 may be so arranged in accordance with its desired heating pattern, that one burner may fire beneath each roller 36 from one side of the furnace toward the other. Combustion gases from such underhearth burning may rise between :rollers 36 Where not prevented by the presence of work spanning such rollers toward flues 71 in the roof of furnace 10, through which flues 71 the combustion gases are exhausted after performing their heating function. If a change in the heating characteristic of the furnace is required, the burner, which is not illustrated, may be withdrawn from alignment with a particular tunnel 69 andthe tunnel may be closed by a cover plate 72, bolts being provided to fasten plates 72 to facing plates 63. Generally, plates 72 will be provided with a refractory bung of suitable size, somewhat in the nature of bung 33, where a tunnel 69 is not in use, or a tunnel wall block 61 may be withdrawn and a solid wall block such as those shown in Figures Sand 6 may be substituted therefor, as desired. Generally, a ,wall block 61 and a port block 52 will fit closely enough for closure purposes, suitable distance being provided by the independent boltings, thereof to the sides of an independent embrasure 22 to providev the expansion and contraction space required in furnace service. I

In practice, a roller 36 may be installed, removed and/ or changed, readily, without cooling down a furnace, even if large, and without likelihood of damage either to the roller or to the furnace structure, and without hazard to those engaged in any such activity. For such an operation, a movable platform which may be in the form of a channel skid 73 may be provided, or dolly wheels may be included along the bottom of the platform, if desired. As shown, platform skids 73 may be a channel section having upstanding flanges 74 and a base 75. Sled ends 76 may be welded to channel 73 and a perforation 77 provided through such ends for engagement thereof by a pole hook (not shown) or by chains 77a. The height of sides 74 is suflicient so that when carrying a roller as shown in dotted lines in Figure 11, the lowermost element 78 of such a roller will not touch either of the sled ends 76 or the bottom 75 of platform 73. In removing a roller 36 in a furnace 10, for example, as shown in Figure 4, the wall blocks 61 beneath that particular roller 36 are removed and the lower port block section 54 immediately above such wall blocks 61 is also removed. In such removal, as will be understood, if a burner is attached to one of the wall blocks 61 so removed, it is first shut off and disconnected, since such burner connections are usually made in a readily disconnectible manner. Even on the drive side of furnace 10, the space between the upper and lower reaches of chain 46 is sufficient to slide out a block 61, the block moving out across the top of channel 20 and onto level 15 outside of furnace 10, the level of the grade along the sides of furnace 10. The outstanding flange of stiffener 68 may be perforated to be engaged by hooks for such purpose after the bolts or nuts holding the blocks 61 to the side of embrasure 22 are loosened and removed. The port block section 54 may be loosened from the structure of furnace 10, lowered and pulled out onto floor 15 at each end of the roller 36 to be removed. Thereupon, a sling comprising a beam 79, chains 79a and hooks 79b, suspended from a crane hook, for example, is maneuvered so that the hooks 79b engage the ends 38 of the roller 36 outside of furnace 10. When the sling is just about in supporting relation to a roller 36 engaged by it, bearings 42 can be disconnected from brackets 45. Then, the crane hook can be lowered to lower such roller 36 into a platform 73 in furnace beneath the roller as shown in Figure 4.

One relatively simple mode of positioning a platform 73 beneath a roller 36 to be removed involves the use of two chains 77a as shown in Figure 4. Such chains 77a are connected to the respective ends of platform 73 through the holes 77. The leading chain 77a is provided with sufficient slack so that it may readily be snaked or projected through the appropriate embrasure 22 having the roller 36 to be engaged. The leading chain 77a is pulled to pull platform 73 into the furnace 10. Then both chains 77a. may be used to position platform 73 immediately beneath the roller 36 in that embrasure. When the roller 36 has been lowered into the platform 73, the leading chain is again pulled, as shown in Figure 4, to remove the lowered roller 36 by pulling it and the platform 73 out of furnace 10 onto floor into a position like that shown by dot-and-dash lines in Figure 4. The following chain 77a by the same operation is pulled so it extends through furnace 10 ready for a reversing operation.

Inasmuch as adjustment mechanism 41 may have tempered springs therein in one new kind of refractory roller 36, such a roller 36 would be removed by pulling skid 73 in the direction of arrow 80 whereby mechanism 41 would not pass through furnace 10 which, as described above, may still be hot since no cooldown is required under a practice of this invention, although preferably the other burners in furnace 10 which are at least adjacent to the roller 36 being removed, will have been shut off or turned down before opening the side Walls of furnace 10 immediately beneath the roller 36 to be so removed.

Either in setting up a furnace 10 or in replacing a roller 36 removed as described above with the same or with another roller 36, the steps just recited are reversed. That is, a roller 36 is placed on a platform 73 on the right-hand side of a furnace 10 if the roller 36, for example, has an adjustment mechanism 41 therein. wise, the insertion of a roller 36 into a furnace 10 may take place from either side.

With a roller 36 on skid 73 outside of furnace 10, the platform is then pulled back into furnace 10 by the trailing chain 77a, on the right-hand side of Figure 4, which moved into the furnace 10 at the time the preceding roller 36 was removed from that embrasure. When the ends 38 of such a newly inserted roller 36 project beyond the respective sides of furnace 10, both ends 38 may be engaged by the hooks 79b. Thereupon,'the sling 79 is raised also raising the bearings 42 in the illustrated embodiment until such bearings 42 can be coupled to their respective brackets 45. At that point, skid 73 and chains 77a are removed from furnace 10, the sling is loosened and carried off and the port block sections 54 and the wall blocks 61 are replaced. If one of those wall sections has a burner tunnel 69 therein, the burner can be reconnected to the outer end of that tunnel and the furnace is ready to start or resume operation as the case may be.

In the case of relatively small furnaces, it may be possible to conduct such a roller installation replacement or change by removal of wall'member sections on one side onlyof the furnace, since the leading end of the roller may be-tilted upwardly, for example, by a bar inserted through the port on the side of the furnace away from the wall opening to guide such leading end of the roller through its port and port opening. Once in transverse position, such a smaller furnace roller can be. reconnected and the open embrasure reclosed so that furnace operations can commence or recommence.

Various modifications may be made in the aspects of this invention without departing from the spirit thereof or the scope of the appended claims.

I claim:

1. In a roller hearth furnace, in combination, a side wall having an embrasure for a roller, said embrasure extending from the operative height at which said roller operates in said furnace downwardly substantially at least to the height of flooring alongside said wall, means for rotata'bly supporting said roller at said operative height in said furnace, and at least one wall member closing said embrasure which is removable below said operative height, whereby when said removable wall member is removed and said roller is disengaged from its support, it may be lowered and removed from said furnace at the level of the bottom of said embrasure.

2. In a roller hearth furnace, in combination, side walls, opposed embrasures in said side walls for a roller, said embrasures extending from the operative height of said roller in said furnace substantially to an outside support alongside said side walls and below said operative height, a bracket connected to said furnace adjacent each of said embrasures, a bearing supported by said bracket to support an end of said roller in operative position, a removable wall block closing the lower part of each of said embrasures, and a port block closing each of said embrasures at said operative height, said port blocks having an opening for the ends of said roller to pass from the inside of said furnace to said bearings.

3. In a roller hearth furnace, in combination, side walls, opposed embrasures in said side walls for a roller, said embrasures extending from the operative height of said roller in said furnace substantially to a generally fiat support alongside said side walls and below said operative height, a bracket connected to said furnace adjacent each of said embrasures, said bracket having a portion above the center line of said roller when said roller is at said operative height, a bearing suspended from said bracket to support an end of said roller in Otherflooring alongside-said walls, a bracket connected to said furnace and extending across the outside of each of said embrasures, said bracket having a portion adjacent the center line of said roller when said roller is at operative height in said furnace, a bearing mounted on said bracket to support an end of said roller in operative position at said operative height, a removable wall block closing the lower part of each of said embrasures, said wall block consisting at least in part of insulating ma- ;terial and having a shape fittinglinto such lower part of each of said embrasures to provide a closure section of said side walls, and a port block closing each of said embrasures above said wall blocks, said port blocks consisting at-least in part of insulating material and having a shape fitting into each of said embrasures to provide a removable port closure section of said side walls, each of said port blocks being divided and having an opening along its line of division for the passage of an end of said roller from the inside of said furnace to the bearings adjacent said port blocks respectively.

5. In an operation of a roller hearth furnace having walls and a roller at operative height extending between said walls, thesteps comprising, in combination, support- "ing said roller at said operative height from above the center line of said'roller, removing wall sections adjacent the ends of said roller to provide openings in said furnace walls extending downwardly from said operative height, extending a platform for said roller into said furnace through one of said openings to a position beneath said roller, releasing said roller from its supports, lowering said roller onto said platform, and moving said platform out of said furnace through one of said openings to remove said roller below said operative height.

6. In an operation of a roller hearth furnace having parallel vertical side walls extending upwardly from grade, embrasures and removable closures therefor extending from said grade upwardly at least to operative height of the rollers in said furnace, said rollers having their respective ends projecting through openings in said closures during operation at said operative height, said rollers further being supported at said operative height from above the center line of said rollers, the steps comprising, in combination, removing said closures adjacent the ends of a roller to be removed to uncover said embrasures, moving a platform at grade into said furnace beneath said roller, releasing said roller from its supports, lowering said roller by means outside said furnace onto said platform, moving said platform and roller out of said furnace through one of said embrasures, and trailing a chain behind said platform and into said furnace during said last-mentioned moving whereby reversing the References Cited in the file of this patent UNITED STATES PATENTS Lee Oct. 26, 1926 Kathner May 15, 1928 Kathner Aug. 20, 1929

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