US3915441A

US3915441A - Heating furnace of walking beam type

Info

Publication number: US3915441A
Application number: US435963A
Authority: US
Inventors: Toshiaki Matsukawa; Masayuki Yamamoto
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1973-01-24
Filing date: 1974-01-23
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28
Also published as: GB1428293A; FR2214872A1; IT1009583B; FR2214872B1; DE2402782A1; DE2402782B2; AU6471774A; AU475264B2; CA1010648A; BR7400500D0

Abstract

A walking beam type heating furnace consisting of movable skid beams and fixed skid beams, wherein the fixed skid beams are supported by cross beams each having both ends fixed on the side walls of the heating furnace, with intermediate members downwardly extending from each of the fixed skid beams to a cross beam so as to make a prescribed space between the fixed skid beams and the cross beams; support pipes for supporting the movable skid beams being fixed on the hearth; and said hearth being formed for free movement by connection with a driving device.

Description

United States Patent Matsukawa et a1. Oct. 28, 1975 HEATING FURNACE 0F WALKING BEAM 3,606,280 9/1911 Gentry 266/5 H x TYPE 3,633,885 1/1972 Beck 432/122 3,656,720 4/1972 Westeren et al 432/122 [75] Inventors: Toshiaki Matsukawa; Masayuki Y t b th f Ki k h FOREIGN PATENTS OR APPLICATIONS Japan 456,803 3/1928 Germany 432/126 [73] Assignee: Nippon Steel Corporation, Tokyo,

japan Primary ExaminerRoy Lake Assistant ExaminerPaul A. Bell [22] Filed: 1974 Attorney, Agent, or FirmWenderoth, Lind & Ponack [21] Appl. No.: 435,963

[57] ABSTRACT Foreign Application Priority Data A walking beam type heating furnace consisting of Jan. 24, 1973 Japan 48-11070 movable skid beams and fixed skid beams, wherein the May 2, 1973 Japan 48-52091 fixed skid beams are supported by cross beams each having both ends fixed on the side walls of the heating [52] US. Cl. 266/5; 266/5 F; 432/11; furnace, with intermediate members downwardly ex- 432/121 tending from each of the fixed skid beams to a cross [51] Int. Cl. F27b 9/14 beam so as to make a prescribed space between the [58] Field of Search 198/279; 266/5 H; 432/11, fixed skid beams and the cross beams; support pipes 432/127, 122, 123, 126, 133 for supporting the movable skid beams being fixed on the hearth; and said hearth being formed for free [56] References Cited movement by connection with a driving device. UNITED STATES PATENTS 10 Claims, 15 Drawing Figures 2,017,024 10/1935 Cochran et a1. 266/5 H X US. Patent Oct. 28, 1975 Sheet 2 of4 3,915,441

m m VII US. Patent 00:. 23, 1975 Sheet 4 of4 3,915,441

. 1 HEATING FURNACE OF WALKING BEAM TYPE BACKGROUND OF THE INVENTION The present invention relates to the improvement of a walking beam type heating furnace and more particularly is directed toward the apparatus provided in the heating furnace consisting of fixed skid beams and movable skid beams for transporting heated materials.

Generally speaking, the transporting apparatus of the heating furnace of the walking beam type consists of a number of rows of fixed skid beams and of movable skid beams and a device for driving the movable skid beams.

For transporting heated materials such as steel slabs in the furnace, parallelogrammic movement of movable skid beams is so repeated that heated materials which have been charged onto fixed skid beams, are advanced stepwise on fixed skid beams. Compared with the pusher type, the walking beam type of the transporting apparatus of the heating furnace has many advantages, some of which are: The heated materials have little skid mark left thereon; operations can be done in various ways; and the materials are not removed from the beams while heated in the furnace. Therefore, this type of transporting apparatus has recently become quite popular.

On the other hand, even the walking beam type of heating furnace, particularly its transporting apparatus, can not be completely free from the following structural problems: As a seal box is provide for every support pipe of the movable beams, the opening on the hearth is so wide that thermal efficiency is lowered, and also the driving mechanism for the sealing device at such opening is complex. Skilled persons in this art are racking their brain to solve such problems.

Speaking about the problem with the operation of the furnace for heating rolled product, while the materials are heated in the furnace, scale peels off the surface of the material, and forms deposits on the hearth. If such deposits grow in height, they will standin the way of the burner flame, which therefore will not reach the central part of the furnace, resulting in insufficient heating in this part and nonuniform heating of the materials, which means degraded quality of rolled product. Particularly in the high temperature heating furnace of the walking beam type, molten scale flows in the opening where a support pipe runs through the hearth, and such scale solidifies around there so as to cover the opening, impeding the function of the support pipe, which may finally stop the operation of the furnace.

In order to prevent such problems, the conventional furnace is so devised that scale is scraped out through trouble holes provided on the side wall during heating operation, or molten scale is discharged after the furnace body is cooled after the operation. However, in the former measure, rapid cooling of the furnace body by water spray into the furnace damages the brick structure and causes spalling or like troubles in the worst case.

Besides, such works as mentioned above require heavy physical labour from operators working under severe conditions, and also stoppage of operation of the fumace once every month or two, for about two days during one stoppage, which means very low productivity of the furnace.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heating furnace of the walking beam type, with thermal efficiency maintained very high because of a small 'number of openings provided on the hearth.

Another object of the present invention is to provide a heating furnace of the walking beam type, equipped to automatically discharge deposits of scale, made during heating operation, thereby preventing troubles caused by such deposits of scale.

A further object of the present invention is to provide a heating furnace of the walking beam type with the structure below the hearth being so simple as to greatly save construction cost.

These and other objects of the present invention will be made clearer by reference to the below-mentioned detailed description and embodiment.

In order to achieve the abovementioned objects, the heating furnace of the walking beam type according to the present invention is so characterized that in the walking beam type heating furnace, consisting of movable skid beams and fixed skid beams, such fixed skid beams are supported by cross beams having both ends fixed onthe side walls of the heating furnace, with intermediate members extending downwardly from each of the fixed skid beams to a cross beam so as to form a prescribed space between the fixed skid beams and the cross beams; support pipes for supporting such movable skid beams are fixed on the hearth; and said hearth is formed for free parallelogrammic movement by connection with a driving device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are elevations in section respectively showing an embodiment of the walking beam type heating furnace according to the present invention.

FIG. 3 is a plan view of part of the heating furnace of FIG. 2. FIG. 4 is an elevation in section of another embodiment of the walking beam type heating furnace improved according to the present invention.

FIG. 5 is a sectional view of the heating furnace of FIG. 1 taken on the line V V of FIG. 4, to show part of said heating fumance.

FIG. 6 is a side elevation in section of the heating furnace of FIG. 4.

FIG. 7 is a sectional view of the heating furnace of FIG. 6 taken on the line VII VII of FIG. 6.

FIG. 8a and FIG. 8b are sectional views of an embodiment of the connection mechanism between a cross beam and a fixed skid beam according to the present invention.

FIG. 9 and FIG. 10 are explanatory sketches of embodiments of the structure of the opening on the hearth according to the present invention.

FIG. 11 is a sectional view of part of the heating furnace of FIG. 4.

FIG. 12 is a diagram showing a driving cycle of the walking beam.

FIG. 13 is an elevation in section of another embodiment of the heating furnace of the present invention.

FIG. 14 is a sectional view of part of the heating furnace of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, numeral 11 indicates a fixed skid beam; and numeral 21 indicates a movable skid beam; both being constructed with a pipe which has cooling water circulating inside for cooling itself.

As for the strucutre of the skid beams for holding tobe-heated material M, there is no type peculiar to the apparatus of the present invention. Any of the rail type, stud type or the like may be used,

Each of the fixed skid beams 11 are supported by cross beams 16 through respective intermediate members 12. The cross beams 16 are provided in the width direction of the heating fumance, in parallel with the surface of the hearth and spaced at appropriate intervals along the longitudinal direction of the heating furnace, both ends of each cross beam being fixed on side walls 2 of the heating furnace I.

Said intermediate member 12 is provided for preventing the movable skid beam 21, during a movement, from hitting the cross beam 16. For this purpose, it may be formed into I-shaped tubular member 13 integrated with the fixed skid beam 11 and communicating therewith as shown in FIG. 8a or into inverted T- shaped tubular member 14 integrated with the tubular cross beam 16 and communicating therewith as shown in FIG. 8b, thereby making cooling water coming through the-fixed skid beam 11 and the cross beam 16 run, respectively, through the tubular member 13 and 14. In this case, provision of baffle plate in side such pipe increases the cooling effect, such plate extending downward or upward to turn, respectively, down or up, cooling water coming horizontally, respectively through the fixed skid beam 11 or the cross beam 16, so as to have the flow reach the lower end or the upper end of respective tubular members.

Said movable skid beam 21 is supported by support pipes 22, which are fixed on hearth 23 constituting the bottom of the heating furnace 1. The hearth 23 covers the bottom of the heating fumace 1, but it has an appropriate space from the wall of the heating furnace provided for its vertical and forward and backward movements. Said hearth 23 is connected with driving device 31 so as to make parallelogrammic movement. As for the driving device, any of the lever type, roller type or motor cam type may be used.

The driving device 31 used in this embodiment, is of the lever type as shown in FIG. 6. Referring to this drawing, the hearth 23 is supported, through girder 32 (FIG. 4), by a pair of beams 33 extending in the longitudinal direction of the furnace 1. The end of the beams 33 are connected with shift cylinder 34 working on air or oil. Below the beams 33 there is provided lift cylinder 35, with which a plurality of bell cranks 37 are connected through connecting rod 36. Each said bell crank 37 is supported, at its central part, for free rotation, by a shaft 38 supported by a bearing 40. At the tip of each said crank 37 is set a roller 39. Said beams 33 are supported from below by the rollers 39.

In the driving device 31 constructed as mentioned above, the beams 33 are put into forward and backward movement by the shift cylinder 34, and into vertical movement by the lift cylinder 35, the cooperation between these

cylinders

34 and 35 putting the hearth 23, that is, the movable skid beams 21 into such parallelogrammic movement as mentioned above.

In FIG. 1, numeral 3 indicates an opening, which is equipped with sealing device 4, such as water seal. In case the present invention is applied to the heating furnace of the type which allows scale to melt, it may be so devised that the central part of the hearth 23 is elevated with a downward slope to respective side walls 2 and molten scale runs to the wall part on both sides, so that it flows into scale box 41 provided at each opening 3, as shown in FIG. 9. In addition, a heating source (not shown) is provided near the opening 3, so as to facilitate the flowing-in of molten scale. In order to also facilitate discharge of molten scale, there may be provided water jets 42 for crashing scale. Also, as shown in FIG. 10, the cetral part of the hearth may be lowered.

FIG. 2 and FIG. 3 show another embodiment of the heating furnace of the present invention.

In this heating furnace, each cross beam 16 is supported by an intermediate support 17 having its lower end fixed on the foundation 6 and extending perpendicularly through an opening 18 provided on the hearth 23. Such opening 18 is a hole of sufficient width as to allow the hearth 23 to make its foward and backward movement free from the intermediate support 17. The part of the opening 18 through which the intermediate support 17 runs is sealed with sealing device 19. As for the number of intermediate supports used for one cross beam, it may vary from one, as in the case of this embodiment, to any plurality.

This embodiment is suited particularly for a heating furnace of great width, since a cross beam that is supported only at both ends must be large in order to be as strong as required, but such length causes the following complications.

In case of cooling such cross beam with water, heat loss is great, reducing thermal effiency and hindering heat transmission to the bottom surface of heated material. This, in turn, increases the requirement of cooling water.

These complications take place particularly frequently with heating furnaces of more than 7 or 8 meters wide.

However, even such furnace can be free from such complications, if the cross beams are supported at their central part respectively with the intermediate support.

The heating furnace of FIG. 4 is equipped with a mechanism for automatically discharging molten scale.

Numeral 51 indicates a scale scraper, which lies parallel with the surface of the hearth 23, having both ends fixed respectively on the lower part of side walls 2. As for the setting position of the scale scraper on the side wall 2, it is so determined that when the hearth 23 reaches the highest position while making parallelogrammic movement, said scale scraper 51 should be close to the surface of said hearth 23. Such scale scrapers 51 are made of heat resisting steel, or, in the case of this embodiment, they are constructed with watercooled pipe, and it will be more effective for preventing degradation of thermal efficiency of the furnace as well as melting of the scraper if said scale scrapers 51 are also lined outside with a refractory material 52. Furthermore, provision of a downward projection 53 at the part for direct scraping of scale, will be very effective for the prevention of peeling off of the lining 52. As for the shape of such scale scrapers 51, anything will do, if it meets the purpose. A plurality of such scale scrapers 51 are disposed at appropriate intervals along the longitudinal direction of the heating furnace' Numeral 54" indicates an opening'rnade on the 's ur faceof thehearth 23, for letting scale, which has been scraped by the scale scrapers 51, fall thr'ethrough. The scale is then discharged through scale discharging chute 55, et'cfou't of the heating furnace. As for intervals in the long direction of the heating fuma'ce andsetting positions of the scale scrapers 51 and the opening 54, they should be determined by taking into consideration cycles of parallelogrammic movement; More particularly regarding the setting position -of theopenings 54, they should be within orzatthe-end of the zone where the scale scrapers'51 function.

In FIG. 13, the cross beam 16 is supported by intermediate supports 56, each lower'end of whichisfixed on'the foundation 6. In the case of the heating furnace which, has such intermediate supports 5.6 for, across beam 16, fixation of a scale scraper 51 on the intermediate supports 56, as shown in FIG. 14, will increase the strength of the scale scraper 51, making it possible to reduce the diameter of the scale scraper 51 and resulting in raising thermal efficiency.

, The operation of the apparatus of the present invention, which has the abovementioned structure, is explained, as follows, by reference to FIGS. 11 and 12.

When the hearth 23 is raised by the driving device from the point A to the point B on FIG. 12 (FIG. 11 shows the situation when the hearth stays at the point A), the tip of the scale scraper 51 enters into the deposit of scale S, making the distance h to the surface of the hearth 23 very small. When the hearth 23 moves from the point B to the point C, scale S on the hearth 23 is scraped by the scale scraper 51 in the direction (with the arrow F) reverse to the direction (with the arrow R) of movement of the hearth 23, and then it falls through the openings 54 into the scale discharging chute 55, to be discharged out by jetting water or the like. The hearth 23 moves from the point C to the point D, and then returns to the point A. As there is a limitation on the walking stroke (B C in FIG. 12), this must be taken into consideration in designing such setting position of the scale scrapers 51 as to have no deposit of scale left after scraping, particularly around said position, thereby preventing the burner flame from hitting a deposit of scale, and greatly raising thermal efficiency.

As mentioned above, the heating furnace of the present invention is so constructed that the hearth itself makes a parallelogrammic movement, thereby driving movable skid beams, with the following advantages over the heating furnace of conventional type:

a. A smaller number of openings are required, thereby greatly raising thermal efficiency and reducing the number of necessary seal boxes. Besides, as the setting position of each of the seal boxes is near respective side walls, broken pieces of refractory lining materials rarely go therein, making the maintenance easier. In the furnace of conventional type, seal boxes are provided for every row of movable beams (more than four rows in ordinary cases), leaving a clearance about 400 mm wide. But, according to the present invention, the number of rows is two, and the clearance between them may be as little as 50 to lOO mm.

b. The foundation of the heating furnace according to the present invention need not be as deep as in the case of the heating furnace of conventional type; and such foundation having less depth will save construction costs."

In the case of the heatingfurnace the conventional type, it has seal boxes' provided below the hearth, and also the walking beam frame below the seal boxes,

making it necessary to build the foundation considerably deep, which increases construction costs and the construction period. 7

According' to the present invention, the structure below the hearth is so simple that the depth of the foundation is required to be only 800 to 1,000 mm.

c. In the case of the conventional type furnaces, a support pipe of the movable beam is fixed on the walking frame, so that it is long and easy to deform, causing nosing of heated materials when they are transported through the furnace. According to the present invention, such pipe is fixed on the hearth, therefore, it is so short as-to be free from such problems as mentioned above with the furnace of conventional type, and increases the stability of its operation. Also, the shorter size of support pipe decreases the size of inner pipe which is inserted into the support pipe, making periodical inspection and maintenance very easy. d. According to the present invention, deposits of scale can be automatically discharged by a very simple mechanism.

What is claiamed is:

1. In the heating furnace of the walking beam type including a hearth and movable skid beams and fixed .skid beams, the improvement which comprises:

cross beams positioned in the width direction of the heating furnace, in parallel with the surface of the hearth at intervals for supporting said fixed skid beams, each of said cross beams having both ends fixed on side walls of the heating furnace;

intermediate members extending downwardly from a fixed skid beam to a cross beam so as to form a required space between the fixed skid beams and the cross beams; support pipes connecting said movable skid beams and the hearth; and

a driving device connected with the hearth so as to have the hearth make parallelogrammic movement.

2. The heating furnace as claimed in claim 1 wherein each said intermediate member is a T-shaped tubular member, integrated with a tubular fixed skid beam and communicating therewith, with a baffle plate extending perpendicularly downwardly inside each of the intermediate members, cooling water flowing from the fixed skid beams through said intermediate members.

3. The heating furnace as claimed in claim 1 wherein each said intermediate member is an inverted T-shaped tubular member integrated with a tubular cross beam and communicating therewith, with a baffle plate extending upwardly inside each of the intermediate members, cooling water flowing from the cross beams through said intermediate members.

4. The heating fumace as claimed in claim 1 wherein said hearth has its central part elevated with a downward slope to respective side walls of the heating furnace, each side wall of the furnace defining an opening with said hearth, molten scale being discharged from the openings.

5. The heating furnace as claimed in claim 1 wherein said hearth has an inclination from the outer part toward the central part, said central part defining an opening, molten scale being discharged from said openmg.

6. The heating furnace as claimed in claim 1, wherein said cross beam is supported by an intermediate support having a lower end fixed on the foundation, and extending perpendicularly through an opening provided on the hearth.

7. In the heating furnace of the walking beam type including a hearth and skid beams and fixed skid beams, the improvement which comprises cross beams positioned in the width direction of the heating furnace, in parallel with the surface of the hearth and at intervals for supporting said fixed skid beams, each of said cross beams having both ends fixed on side walls of the heating furnace; intermediate members extending downwardly from a fixed skid beam to a cross beam so as to form a required space between the fixed skid beams and the cross beams; support pipes fixing said movable skid beams on the hearth; a driving device connected with the hearth so as to have the hearth make parallelogrammic movement; scale scrapers provided in the width direction of the heating furnace, in parallel with the surface of the heating furnace and at intervals, each of said scale scrapers having both ends fixed on the lower part of side walls of the heating furnace, said hearth having openings for discharging scale.

8. The heating furnace as claimed in claim 7, wherein the outer surface of each of said scale scrapers is lined with a refractory material.

9. The heating furnace as claimed in claim 7, wherein each of said scale scrapers has a projection pointing downwardly for scraping scale.

10. The heating furnace as claimed in claim 7, wherein each said scale scraper is fixed on an intermediate support having its upper end and lower end fixed,

respectively, on a cross beam and the foundation.

Claims

1. In the heating furnace of the walking beam type including a hearth and movable skid beams and fixed skid beams, the improvement which comprises: cross beams positioned in the width direction of the heating furnace, in parallel with the surface of the hearth at intervals for supporting said fixed skid beams, each of said cross beams having both ends fixed on side walls of the heating furnace; intermediate members extending downwardly from a fixed skid beam to a cross beam so as to form a required space between the fixed skid beams and the cross beams; support pipes connecting said movable skid beams and the hearth; and a driving device connected with the hearth so as to have the hearth make parallelogrammic movement.

4. The heating furnace as claimed in claim 1 wherein said hearth has its central part elevated with a downward slope to respective side walls of the heating furnace, each side wall of the furnace defining an opening with said hearth, molten scale being discharged from the openings.

5. The heating furnace as claimed in claim 1 wherein said hearth has an inclination from the outer part toward the central part, said central part defining an opening, molten scale being discharged from said opening.

10. The heating furnace as claimed in claim 7, wherein each said scale scraper is fixed on an intermediate support having its upper end and lower end fixed, respectively, on a cross beam and the foundation.