US3345050A - Furnace skid rails - Google Patents

Description

1957 J. M. GUTHRIE 3,34

FURNACE SKID RAILS Filed Aug. 25, 1965 4 Sheets-Sheet.1

INVENTOR. JAMES M. eumma.

51%;; aka MU ATTOR NEYS- J. M. GUTHRIE Oct. 3, 1967 FURNACE SKID RAILS 4 Sheets-Sheet 2 I Filed Aug. 25, 1965 INVENTOR. JAM E5 M. GUTHRIE.

ATTORNEYS.

Oct. 13,1967 J. M. GUTHRIE 3,345,050

FURNACE SKID RAILS Filed Aug. 25, 1965 4 Sheets-Sheet 3 INVENTOR. JAMES M.6UTHRIE.

BY may M Md MAZ ATTORNEYS.

Oct. 3, 1967 J. M. GUTHRIE 3,345,050

FURNACE SKIID RAILS Filed Aug. 25, 1965 4 Sheets-Sheet 4 INVENTOR. JAMES M. GUTHRIE.

at; M aha/M ATTORNEYS.

United States Patent 3,345,050 FURNACE SKID RAILS James M. Guthrie, Crafton, Pa., assignor to Loftus Engineering Corporation, a corporation of Maryland Filed Aug. 25, 1965, Ser. No. 482,405 13 Claims. (Cl. 263-6) ABSTRACT OF THE DISCLOSURE This disclosure relates to fuel-fired furnaces, known as continuous or pusher type furnaces, in which steel slabs, blooms, billets, ingots, or other forms of metal articles are heated to rolling, forging or other desired temperature. One row, or more, of such articles is supported on water-cooled skid rails extending between the charging end of the furnace and a refractory soaking or discharge hearth located adjacent to the opposite end of the furnace. The articles to be heated are mechanically pushed intermittently into the charging end of the furnace, causing the row of articles correspondingly to advance to discharge position on the soaking hearth. In their sojourn in the furnace the articles are heated to desired temperature, except those portions of the articles in contact with the skid rails. Those portions are at a lower temperature than the remainder of the articles, forming what are known in the art as skid marks, which cannot be removed during the time the articles are thermally soaked on the discharge hearth, at least not without the articles dwelling on the hearth for so long a time as to reduce the production of the furnace to a prohibitive degree. In order to reduce the cooling effect of the skid rails on the engaged body portions of the metal articles, novel means are combined with the skid rails to arrest or diminish the thermal conductivity between such rails and the bodies of the articles supported thereby.

My present invention relates to continuous or pushertype furnaces for heating slabs, ingots, billets, or like heavy articles of metal, to be heated for rolling, forging, or other shaping operation.

More particularly, the invention is concerned with the water-cooled skids that support the articles to be advanced step by step through the furnace and heated to working temperature during their sojourn in the furnace.

Hitherto, the problem in operating such furnaces is to eliminate skid marks in the heated articles discharged from the furnace, skid marks being darker colored regions in the heated articles which, due to contact with the water-cooled skids, are at lower temperature than the rest of the bodies of the articles. These skid marks or regions of lower temperature in a heated article to be rolled, or otherwise shaped, prevent or impair the obtainment of a uniform product. It has been the practice in the art to provide a soaking hearth in the furnace, on which hearth the heated articles are allowed to dwell in the hopes that the skid marks will be soaked out; that is, the entire body of each heated article will be brought to uniform temperature. The latter practice has proved to be of some benefit, but the results have never been completely satisfactory, since, if the heated articles are allowed to soak long enough to completely remove the skid marks, the production of the furnace is curtailed to an impractical or economically prohibitive degree.

The object of my invention is to provide a solution of this problem; that is, to provide a skid construction which will inhibit or substantially eliminate skid marks, while maintaining optimum production rates of the furnace. An ancillary object is to provide thermal insulation for the water-cooled skids whereby the skids will 3,345,050 Patented Oct. 3-, 196-7 be protected against furnace heat, or, otherwise expressed, the amount of furnace heat lost or dissipated by the water-cooling of the skids will be minimized.

The invention will be understood upon reference to the accompanying drawings, in which:

FIG. 1 is a view in central longitudinal section of a pusher-type furnace in which my invention is useful;

FIG. 2 is a fragmentary isometric view illustrating features of the invention;

FIG. 3 is a fragmentary view, showing in side elevation a certain water-cooled header used in securing and supporting the water-cooled pipes of which my improved skids are constructed;

FIG. 4 is a view in plan from above of the structure shown in FIG. 3; a

FIG. 5 is a sectional view of the latter structure, as seen on the plane V-V of FIG. 4;

FIG. 6 is a fragmentary sectional view of the structure, as seen on the plane VIVI of FIG. 3;

FIG. 7 is a view of the header structure, as seen from the right of FIG. 3, but omitting certain refractory blocks and refractory rail elements;

FIG. 8 is a view in cross-section, showing a pair of water-cooled pipes in cross-section, and illustrating a modification in the form of the refractory blocks that are of double utility; they support the refractory rail elements and thermally insulate the pair of water-cooled p p FIG. is a view similar to FIG. 8, but showing a single Water-cooled pipe as the support for the refractory blocks and refractory rail elements;

FIG. 10 is a view in cross-section of a pair of watercooled pipes, similar to the showing of FIG. 8, but illustrating that each refractory supporting block may be formed in one piece rather than in two;

FIG. 11 is a view corresponding to FIG. 9 of a single water-cooled pipe arranged within refractory supporting and insulating blocks of integral construction; and

FIG. 12 is a view in cross-section of a single watercooled pipe having refractory blocks .of bipartite construction suspended from the pipe for the purpose of insulating the water-cooled pipe from furnace heat.

Referring to FIG. 1 of the drawings, a furnace of the sort in which the improvements of my invention are particularly advantageous is indicated generally at 1. In this case the furnace is designed to heat slabs S of steel as they are successively advanced step by step through a preheating section 2, a heating section 3, and a soaking section 4. Extending longitudinally from the charging doorway 5 of the furnace to the soaking hearth 6 are laterally spaced skids 7, and below these skids a system of burners 8 directs burning columns of fluid fuel and combustion air for heating the slabs from beneath, while a system of burners 9 functions to heat the slabs from above, in the course of their travel through furnace heating sections 2 and 3.

The slabs S are carried to the charging end of the furnace on a roller table 10, whence they are pushed in required sequence over a charging platform 11, through the furnace charging door 5 and upon the skids 7. The pusher mechanism for this purpose is well-known in the art, wherefore such mechanism is not shown herein. During normal furnace operation, one or more lines of slabs extend continuously from the charging door to the dis charge knuckle 12 of the soaking hearth. The soaking zone is fired from above by means of system of burners 13. When it is desired to deliver a slab from the furnace, a cold slab is pushed through charging door 5 into the furnace; this advances the entire line of slabs by a distance approximately equal to the width of the entering slab, with the consequence that the end slab on the soak ing hearth falls to the discharge slope 14 and slides to a 3 roller table 15 that propels the heated slab to a rolling \mill. The foregoing general description of the pushertype furnace illustrated herein will suffice for this specification, and attention will now be directed specifically to the improvements wherein my invention is found.

The entire skid structure 7 may be constructed throughout its length between the charging door 5 and the soaking hearth 6 in such way that no skid marks occur in the slabs S, with the consequence and effect that the soaking hearth may be economically constructed in shorter length than it normally is. Conceivably in some instances, by virtue of my invention, the soaking hearth may be substantially eliminated, with substantial savings in the cost of the furnace. In the present case, however, I prefer that the skid structure 7 may be of conventional construction, except in the reach of the structure between point 16 in the furnace and the soaking hearth 6, and it is in this reach the skid marks imparted to the slabs S between the charging door 5 and point 16 will, due to the skid structure described below, be removed before the slabs reach the soaking hearth.

Referring to FIG. 2 of the drawings, it will be understood that there are two or more parallel skid structures 7 laterally spaced across the width of the furnace 1. Each skid structure in its extent between the charging end 5 of the furnace and the point 16 (FIG. 1) may be of conventional construction, formed as a beam of extra heavy steel pipe 17. The steel pipe is anchored in usual way to the foundation of the slab-pushing mechanism (not shown) adjacent to the charging end of the furnace, and/or to the adjacent foundation and structural steel binding of the furnace itself. At its opposite or inner end (cf. point 16, FIG. 1) each reach of pipe 17 is secured, as by welding, to a hollow water-cooled header 18 formed of steel. On the top of each skid pipe 17, and throughout the effective length thereof, a steel wearing bar 19 is welded (FIG. 2), and it is on the wearing bars 19 of the four skid structures shown that the slabs S rest; that is, those slabs S of that portion of the row which extends between the charging door 5 and point 16 in the furnace.

In the reach of the skid structure between the point 16 in the furnace and the soaking hearth 6, two laterally spaced extra heavy pipes 20, 20 (FIGS. 2 to 7) extend in parallelism from each header 18 to a header 21 (FIG. 1) adjacent to the soaking hearth 6. The paired pipes 20, 20 are welded at their opposite ends to the headers 18 and 21, respectively, and the interiors of the pipes stand in open communication with the interiors of the hollow headers 18 and 21.

Means are provided for laterally and vertically supporting the skid pipes 17 and 20, 20, whereby the great weight of the slabs S may be sustained by such pipes. Such means comprise extra heavy steel cross pipes 22 on which the said skid pipes rest, and cross pipes 23 that extend through and are welded to the headers 18 and 21. The cross pipes 22 and 23 extend through the opposite side walls of the furnace and are united with the heavy steel buckstays on the outside of the furnace. The manner in which the cross pipe 23 shown in FIG. 2 is supported, as at 24, to the buckstays 24a of the furnace binding will suffice for an understanding of the structural organization of all cross pipes 22 and 23 to provide lateral support for the longitudinal skid pipes 17 and 20, 20 of the furnace. The main vertical support for the skid pipes is provided by means of heavy steel stanchion pipes 25a that bear the cross pipes 22 and stanchion pipes 25 that bear the headers 18 and 21.

The stanchion pipes 24 and 25 extend downwardly through the hearth of the furnace and are secured to the steel hearth-supporting beams 26, as indicated at 27 in FIG. 2.

In FIGS. 1 and 2 of the drawings the hollow watercooled headers 18 and 21 are shown of simple cubical construction, but in FIGS. 3 to 6 the headers are shown to be of more refined design, each including seats 28 for the ends of pipes 17 and 20, 20 welded to the headers, and a socket 28a for engaging the top of a stanchion pipe 25. And as shown in FIG. 5,-each header is provided with an internal cylindrical wall 29, forming a cylindrical passage through which a lateral pipe 23 may extend to permit a circulation of cooling water in such pipe independently of the cooling water circulating through the headers and skid pipes. Each of the stanchion pipes 25a and 25 has a stream of cooling water delivered upwardly into it by a feeder pipe 29 (FIG. 2) that extends almost to the top of the stanchion pipes, and the stream of cooling water flows downwardly between the walls of the stanchion pipe and its feeder pipe 29, whence it exits into any suitable drain.

It is important to note that the paired skid pipes 20, 20 are vertically offset below the horizontal plane of skid pipes 17 (FIGS. 3 and 7), the design of the headers 18 and 21 providing an excellent structural accommodation for this feature. On each pair of skid pipes 20, 20 a series of-refractory saddle blocks 30 is supported, such blocks being arranged in close relation, while providing for such slight movement relative to one another as is occasioned by the flexing of the pipes 20, 20 under the weight of the slabs S as they are pushed through the furnace. The body of each saddle block is provided with seat portions 31 that snugly engage the skid pipes 20, 20 (FIG. 6), and the body portion of each block above the seats 31 form a bearing that includes a recess 33. The recesses in the aligned blocks 30 provide a channel in which a succession of refractory slab-engaging elements 32 is contained. These elements 32 transmit the weight or load of the slabs to the saddle blocks 30. For convenience in expression these members 32 may be termed refractory rail or wearing elements. The top surfaces of the rail elements 32 lie in the horizontal plane of the top edge of the associated rail element 19 that extends between the charging door 5 and point 16 in the furnace. The refractory rail elements 32 may be formed of a fused-cast refractory material such as silicon carbide, or of an electrically cast alumina composition available on the open market under the name Monofrax.

It will be noted that the bodies of refractory blocks 30 include portions 35, 35 and 36 (FIG. 6) that form open-bottomed slots 37, 37 which, when each block is seated on the pipes 20, 20 are closed by refractory disks 38, 38 slipped into place and secured in slots 39. By virtue of the downwardly extending refractory block portions 35, 35, 36 and disks 38, 38 together with the body portions of the blocks above the rails, the skid pipes 20, 20 are enveloped by the refractory blocks, wherefore such blocks serve as saddles to support the rail elements 32 and also serve as themal insulation for the water-cooled pipes 20, 20, protecting the pipes from furnace heat and minimizing the quantity of heat which is withdrawn by the pipes from the furnace and dissipated. It will be noted that each refractory rail element 32 is supported in the aligned channels 33 of a plurality of adjacent blocks 30three blocks in this case. In order to minimize any tendency for the rail elements to fracture or crack under the weight of the slabs S pushed over them, a metal shoe 40 (FIG. 6) of a heat-resisting steel is inserted endwise in the channels 33 of the blocks 30. Each shoe 40 may be equal in length with the rail element 32 it supports.

The tops of the headers 18 are provided with integral metal rail portions 34 that bridge the space between the ends of wearing bars 19 on skid pipes 17 and the adjacent ends of the lines of refractory rail elements 32 borne by blocks 30 and skid pipes 20, 20, as shown in FIG. 2. Similarly, the headers 21 may be provided with rail elements 34 and the slab-bearing top surface of soaking hearth 6.

Thus, a water-cooled skid structure may be provided to meet the aims of this invention.

Referring to FIG. 8, the refractory saddle blocks 30 may be of bipartite construction, each including an upper half 30a and a lower half 30b. The skid pipes 20a, 20a are provided with hanger clips 41, upon which the lower block sections 30b may be engaged, as by means of complementary slots in the block sections 30b, and tongue and groove joints 42 may be provided in the two halves of each block, to assist in maintaining alignment of the halves, and to circumvent infiltration of furnace fumes or gases between the halves. The upper or load-bearing section 30a of each block may include a recess 33a, to provide with adjacent block sections 30a a channel to receive the refractory rail elements 32a, with or without alloy shoes 40a.

FIG. 9 illustrates that in some cases a single watercooled skid pipe 20b may serve in lieu of the paired skid pipes 20, 20 and that the lower section 300 of each bipartite refractory block may be secured by a single T-shaped hanger clip 41a welded to the skid pipe and engaged in a suitable slot in each block section 30c.

FIG. 10 serves to indicate, by way of a further modification that monolithic refractory saddle blocks 30d may be threaded on the paired skid pipes 200, 200 before such pipes are welded at their opposite ends to the headers 18 and 21 (FIG. 1).

In the event a single water-cooled skid pipe 20d is used, monolithic blocks 30e may be threaded on the pipe before it is Welded to the headers 18 and 21. A keeper bar 43 of steel may be welded to the pipe, and a corresponding slot in each block 30c cooperates to insure that all of the blocks in the series of blocks on the pipe will remain in desired alignment.

In the case of the skid pipes that extend between the charging door and point 16 of the furnace, it is desirable thermally to insulate the pipe. FIG. 12 illustrates in cross-section such a skid pipe at 17a, equipped with a steel wearing rail 19a. For this purpose bipartite blocks 30f, 30] of refractory or insulating material may be suspended on the pipe, by means of T-clips 44 welded to the pipe and engaged in complementary slots formed in the block sections.

In the case of the clips 41 of FIG. 8, the clips 41a of FIG. 9, and the clips 44 of FIG. 12, it will be understood that such clips comprise an aligned series of spaced-apart clips that extend longitudinally of the water-cooled skid pipes to which they are welded, with the spaces between successive clips of suflicient scope to permit the lower halves of the refractory blocks in each case to be raised between the adjacent clips and inched along the pipe into suspended positions on the adjacent clips. The lower half of the last block in the series extending between the headers 18 and 21 may be molded in situ of a suitable plastic refractory material.

The skid construction between the point 16 and the soaking hearth 6 of the furnace may be applied to the load-supporting beams of walking beam furnaces of well-known design, in which the water-cooled steel pipes of circular cross-section may comprise one or more water-cooled pipes or hollow water-cooled steel beams of rectangular or other cross-section, such steel beams being considered the mechanical equivalent of circular pipes or beams.

Within the terms of the appended claims other modifications and variations in the skid pipe structure described may be made without departing from the spirit of the invention.

I claim:

1. A skid structure for supporting metal articles to be heated, said skid structure comprising two reaches of water-cooled pipe arranged in longitudinal succession between the charging and discharging ends of the furnace, the water-cooled pipe of the reach closer to the charging end of the furnace having a metal wearing rail secured on its top, the water-cooled pipe of the second reach having a line of refractory rail elements and means for support- 6. ing them on the latter pipe with their top surfaces aligned with the top surface of said wearing rail, the water-cooled pipe of the second reach extending in a horizontal plane that is substantially parallel to but lower than the plane of the water-cooled pipe of said first reach, water-cooled means for uniting the adjacent ends of the pipes of said vertically offset reaches, and water-cooled supports for vertically and laterally supporting said water-cooled means and the reaches of water-cooled pipe.

2. A skid structure for supporting metal articles to be heated in a pusher-type furnace, said skid structure comprising a substantially horizontal pair of laterally spaced parallel water-cooled pipes, two water-cooled headers severally secured to the opposite ends of said pipes, a water-cooled jack vertically supporting each header, water-cooled lateral braces extending outwardly from the opposite sides of each header, a row of closely arranged refractory blocks having load-bearing portions seated on said pair of pipes between said headers, and refractory rail elements borne by said blocks for slideably supporting the metal articles to be heated in said furnace.

3. The structure of claim 2, wherein the seated blocks have bodies that extend downwardly over the bodies of said water-cooled pipes, whereby said blocks provide both a support for said rail elements and a thermal insulation for the pipes against furnace heat.

4. The structure of claim 2, wherein the bodies of said blocks include two slots with open lower ends that receive said water-cooled pipes when the blocks are moved into seated positions on the pipes, and refractory portions engaged to said blocks for closing the lower ends of said slots when the blocks have been seated, whereby said blocks provide both a support for said rail elements and a thermal insulation of the said pipes from furnace heat.

5. The structure of claim 2, wherein said refractory rail elements span a plurality of said refractory railelement-bearing blocks seated on the pipes between said headers, together with a metal shoe interposed between each refractory rail element and the plurality of refractory blocks that bear the rail element.

6. The structure of claim 2, wherein said closely ar ranged refractory blocks seated on said pair of pipes include refractory portions which envelop said pipes from below, whereby said refractory blocks provide both a seat for said refractory rail elements and a thermal insulation for the supporting pipes from furnace heat.

7. The structure of claim 2, wherein said refractory rail elements span a plurality of said refractory rail-elementbearing blocks seated on the pipes between said headers, together with a metal shoe interposed between each refractory rail element and the plurality of refractory blocks that bear the rail element, said rail-element-bearing blocks seated on the pipes between said headers having refractory portions which envelop said pipes from below, whereby the refractory blocks provide both a seat for each refractory rail element and a thermal insulation for the supporting pipes from furnace heat.

8. A skid structure for supporting metal articles to be heated in a pusher-type furnace, said skid structure comprising two reaches of water-cooled pipe arranged in longitudinal succession between the charging and discharging ends of the furnace, the water-cooled pipe of the reach closer to the charging end of the furnace having a metal wearing rail secured on its top, the watercooled pipe of the second reach having a line refractory rail elements and means for supporting them on the latter pipe with their top surfaces aligned with the top surface of said wearing rail, the water-cooled pipe of the second reach extending in a horizontal plane that is substantially parallel to but lower than the plane of the water-cooled pipe of said first reach, a water-cooled header uniting the adjacent ends of the pipes of said vertically offset reaches, and water-cooled means for vertically and laterally supporting said header and the reaches of water-cooled pipe,

the means for supporting the line of refractory rail elements of said second reach comprising a closely arranged series of refractory blocks having load-bearing portions seated on and extending along said second reach of pipe.

9. The structure of claim 2, said refractory blocks having portions that cooperate with said load-bearing portions to insulate the water-cooled pipe of the second reach from furnace heat.

10. A skid structure for supporting metal articles to be heated in a pusher-type furnace, said skid structure comprising a reach of water-cooled pipe anchored at one end adjacent to the charging end of the furnace and extending in a generally horizontal direction toward the discharge end of the furnace, at water-cooled header united to the opposite end of said pipe, a pair of spaced parallel water-cooled pipes united with said header and extending therefrom toward the discharge end of the furnace in a plane vertically offset below the plane of the first-named water-cooled pipe, means for vertically and laterally supporting said header and the pipes united thereto, said first-named Water-cooled pipe having a metal wearing rail secured on its top, said vertically offset pair of pipes having a series of closely arranged refractory blocks seated thereon to form a saddle, and a line of refractory rail elements seated in the saddle formed by said blocks, with the tops of said rail elements in substantial alignment with the top of said metal wearing rail on the firstnamed pipe.

11. The structure of claim 10, said refractory saddle blocks having bodies that substantially envelope said vertically offset pair of pipes, whereby the blocks provide 8 both a support for said refractory rail elements and a thermal insulation for the pipes.

12. The structure of claim 10, wherein said refractory rail elements each span a plurality of said refractory saddle blocks, together with a metal shoe interposed between each refractory rail element and the bodies of the refractory blocks that bear the rail element.

13. A parallel pair of water-cooled skid pipes for supporting articles to be heated in a pusher-type furnace, said skid pipes having hanger means secured thereto, a series of closely arranged refractory blocks, each of said blocks having two separate body portions, one of said body portions having two seats for severally engaging said pipes from above, and the other of said body portions being suspended from said pipes by said hanger means, the two body portions so assembled with the pair of skid pipes providing means for both supporting a refractory rail element and for thermally insulating the pair of pipes.

References Cited UNITED STATES PATENTS 1,262,794 4/1918 Hofmann 263-6 2,295,474 9/1942 Horn 263-6 3,169,754 2/1965 OReilly 2636 3,214,152 10/1965 Molz 2636 3,226,101 12/1965 Balaz et a1. 2636 FREDERICK L. MATTESON, J,R., Primary Examiner.

JOHN J. CAMBY, Examiner.

Claims (1)

1. 2. A SKID STRUCTURE FOR SUPPORTING METAL ARTICLES TO BE HEATED IN A PUSHER-TYPE FURNACE, SAID SKID STRUCTURE COMPRISING A SUBSTANTIALLY HORIZONTAL PAIR OF LATERALLY SPACED PARALLEL WATER-COOLED PIPES, TWO WATER-COOLED HEADERS SEVERALLY SECURED TO THE OPPOSITE ENDS OF SAID PIPES, A WATER-COOLED JACK VERTICALLY SUPPORTING EACH HEADER, WATER-COOLED LATERAL BRACES EXTENDING OUTWARDLY FROM THE OPPOSITE SIDES OF EACH HEADER, A ROW OF CLOSELY ARRANGED REFRACTORY BLOCKS HAVING LOAD-BEARING PORTIONS SEATED ON SAID PAIR OF PIPES BETWEEN SAID HEADERS, AND REFRACTORY RAIL ELEMENTS BORNE BY SAID BLOCKS FOR SLIDEABLY SUPPORTING THE METAL ARTICLES TO BE HEATED IN SAID FURNACE.

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