JP3139674B2 - Fire resistant structure around the stopper nozzle of the bottom pouring ladle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure around a stopper nozzle of a bottom pouring ladle used at the time of casting in a cast steel and steelmaking plant.

[0002]

2. Description of the Related Art FIG. 3 is a front view (A) and a side view (B) showing an entire bottom pouring ladle. A stopper device 10 is attached to a ladle main body 2 manufactured by bending and welding an iron plate. Then, the stopper nozzle is closed, the molten metal is received from the melting furnace, the ladle is transported onto the mold, and the stopper nozzle is opened to cast the molten metal inside. In this case, the mold is poured from the bottom of the ladle as a bottom pouring method so that the molten slag discharged from the furnace together with the molten metal and separated and floated on the upper surface of the molten metal in the ladle is not mixed into the molten metal during casting. Usually, it is in a form to be performed.

[0003] A suitable casting temperature of the molten metal is 14
Since the temperature is generally 50 to 1500 ° C., it is needless to say that the inner surface of the ladle has a refractory structure that can withstand this high heat. Specifically, as shown in FIG. 3, a stopper nozzle 101, which is detachably contacted with a stopper head 7, which is suspended from the upper side so that it can be lifted and lowered from above, is embedded into the bottom of the ladle. To block outflow of molten metal,
When a gap is formed between the stopper head 7 and the stopper nozzle 101 by lifting the stopper head 7, the molten metal flows out through the gap to be cast. This stopper nozzle 101
The cross section of the surrounding fire-resistant structure in which is embedded is shown in FIG. 4.
The nozzle receiving brick 104 set at a position where the stopper nozzle 101 is fitted inside is fixed, and the stopper nozzle 10 fitted in the nozzle receiving brick 104 is fixed.
One nozzle hole is made to coincide with the pouring hole 22 that has been drilled through the bottom surface 21 of the ladle body. In this state, irregular-shaped refractories (for example, alumina powder and a binder) are ground on the bottom brick 3 until the outer peripheral surface of the nozzle receiving brick 104 protruding above the refractory layer 3 is buried. 106 is formed to form a bottom surface extending to the side wall 5 of the ladle main body 2, thereby forming a refractory lining structure capable of withstanding the high heat of the molten metal.

[0004]

FIG. 5 is a cross-sectional view of a main portion of the prior art shown in FIG. 4 in which only the fireproof structure around the stopper nozzle is enlarged. FIGS. 6 and 7 are sectional views of the prior art shown in FIG. Nozzle receiving brick 104 used in
2A and 2B are a plan view and a front view, respectively. As shown in FIG. 5, a pouring port 22 is pierced in a flat surface 21 of the ladle main body 2, a stopper nozzle 101 penetrating a nozzle hole 112 communicating with the pouring port 22 at the center is positioned, and a conical surface on an outer periphery of the stopper nozzle 101 is provided. 111
A nozzle receiving brick 104 having a fitting hole 141 formed at the center and having a reverse slope substantially corresponding to the inclination of the stopper nozzle 101 is fitted around the stopper nozzle 101. As shown in FIGS. 6 and 7, it is customary to generally manufacture the nozzle receiving brick 104 in a square shape or a square shape having one side including an arc surface. In this form, the outer peripheral surface 143 of the nozzle receiving brick 104 is made of an irregular refractory. To form the refractory layer 106. However, in this structure, there are inherent factors that induce various problems, and troubles during casting due to defects in the refractory structure also occur, resulting in workplace safety, cast product quality, and work efficiency problems. Concerns have been raised that have triggered a number of alarming situations.

[0005] A high-temperature molten metal of about 1500 ° C is received from a melting furnace, conveyed to a position immediately above a mold, and is positioned and poured.
The number of molds that can be poured in one tap is not fixed, but the stopper nozzle and stopper head of the ladle that received the hot water are replaced only once. Are rubbed so as not to leak out and flow out of the mold. However, the nozzle receiving brick 104 which supports the stopper nozzle by fitting it from the periphery.
Is a requirement that, like the refractory layer 106 forming the bottom surface of the ladle, is not renewed every time the hot water is received, but is repeatedly used many times while maintaining the refractory function with as little wear as possible. Therefore, it cannot be overemphasized that the number of times of use in the portion directly in contact with the molten metal inside the ladle, particularly in the vicinity of the stopper nozzle, has a very large effect on productivity, economy, and production cost.

However, the nozzle receiving brick 104 and the refractory layer 106 are ignited and expanded each time they receive a high-temperature molten metal, and cannot be escaped from being subjected to a severe thermal cycle in which cooling is repeated with completion of pouring. No matter how much the material itself has a highly reliable fire resistance, there is a limit which is physically hard to withstand. Even if attention is paid only to the nozzle receiving brick itself, as shown in FIG.
In the shortest distance P1: P2 from 41 to the outer peripheral surface 143, 1:
There is a difference of 1.7, and the thickness difference p1: p2 in the vertical direction due to the inclination of the fitting hole 141 also reaches 1: 1.3. On the other hand, as shown in FIG. 7, the difference between Q1 and Q2 is as large as 1: 1.6, and the ratio of q1 and q2 is also as large as 1: 1.25 in the vertical direction. Because it is proportional to the amount of thermal expansion at the time, in the prior art nozzle receiving brick, the internal stress generated by the thermal shock proportional to the difference in the amount of thermal expansion for each hot water exceeds the mechanical strength to form the brick It is understood that this destructive force leads to cracks in the material.

[0007] The negative surface due to the shape has a great influence on the strength of the refractory layer around the nozzle receiving brick. The refractory layer 106 is in contact with the rectangular outer peripheral surface 143 and repeatedly receives different thermal stresses depending on its position. In particular, the rectangular corner portion acts as an edge to concentrate the stress, and when a crack is generated in this portion, it rapidly expands. That is inevitable. Also, when the refractory layer is formed by grinding irregular shaped refractories, it is difficult to compact around the square corners, and the strength itself after molding must be low, so rapid heating and cooling When the heat cycle is repeated, the tendency of cracks and gaps to be generated further increases. Once a gap has been created, there is a great deal of concern that the molten metal will sew through the gap and reach straight down to the bottom of the ladle body after receiving the hot water on the ladle, It has been empirically confirmed that this is the cause.

[0008] As a conventional technique for preventing damage to a stamp material or a brick forming a bottom surface of a ladle, for example, Japanese Utility Model Application Publication No.
In -8597, as shown in Fig. 8, the most severe erosion of the ladle's side walls and the corners on the outer periphery of the bottom surface.
No. 01 peripheral bricks are placed every other or every two bricks, and long bricks 202 that are 30 to 80 mm higher than the bottom bricks are arranged, and are buried with a stamp material 203 that is inclined and filled in the direction of the center of the ladle. FIG. It is stated that this configuration prevented the melting of the corners and solved the reduction in the number of service life, but the gist of this invention was limited to the corners of the ladle, and the loss of fire resistance around the stopper nozzle faced by the present invention. Needless to say, it does not directly address the problem of preventing hot water leaks.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a fireproof structure around a stopper nozzle of a bottom-pour ladle that remarkably improves fire resistance and significantly reduces a leak of molten metal.

[0010]

According to the present invention, a fireproof structure around a stopper nozzle of a bottom pouring ladle according to the present invention comprises a truncated cone-shaped stopper nozzle 1 with which a stopper head 7 suspended and movable up and down abuts. Fixed on the bottom surface 21 of the main body 2,
A nozzle receiving brick 4 having a fitting hole 41 formed of an inverted conical surface in which the conical surface 11 of the stopper nozzle 1 is internally fitted, and having an outer peripheral surface 43 reduced in diameter toward the upper side of the ladle with a step 42. The bottom surface from the outer peripheral surface 43 to the side wall brick 5 of the ladle over the thickness from the bottom brick 3 laid on the bottom surface 21 to the top surface 44 of the nozzle receiving brick 4 is further formed of an irregular-shaped refractory. It is characterized in that the refractory layer 6 is formed by evenly hardening.

With this configuration, the nozzle receiving brick 4 is
As illustrated in FIG. 2, not only are the shortest distances R from the fitting hole 41 to the outer peripheral surface 43 all the same, but the diameter of the fitting hole 41 is also reduced upward with the step 42. The difference in wall thickness r in the vertical direction is greatly absorbed, so that the amount of thermal expansion stays within substantially the same level no matter what the outer peripheral surface is measured, and almost the same amount of expansion and expansion occurs in any part of the adjacent refractory layer 6. The occurrence of cracks and the extension of cracks due to contraction are reliably reduced.

The outer peripheral surface 43 of the nozzle receiving brick 4 is
Each cross section is circular, so when the adjacent refractory layer is polished and formed, a bottom surface with a uniform strength and density that is evenly compacted is formed, and a strong deterrent to prevent cracking. Demonstrate. In addition, since there is provided a step 42 whose diameter is reduced upward, the refractory layer 6 and the outer peripheral surface 4 of the nozzle receiving brick 4 are tentatively subjected to repeated expansion and contraction.
Even if a gap is formed between the refractory layer 3 and the molten metal 3, the molten metal sneaked through the gap collides with the step 42 buried in the refractory layer 6 to block the course and form a resistance zone that blocks traffic at this position. However, there is an effect that a straight line cannot be easily reached to a bottom surface along an outer peripheral surface as in the related art. The problems in the prior art can be largely solved by expressing the above-described specific actions in association with each other.

[0013]

FIG. 1 is a longitudinal sectional front view showing an embodiment of the present invention, and FIG. 2 is a plan view (A) and a front view (B) of only a nozzle receiving brick 4 therein. The ladle main body 2 itself is not particularly different from the prior art, so that the illustration thereof is omitted, and a bottom surface 21 and a pouring hole 22 perforated in the bottom surface 21 are shown in FIG.
Just show. The casting of the molten metal received in the ladle main body 2 is performed by raising the stopper head to be suspended and closely contacting the inner peripheral curved surface of the nozzle hole 12 penetrating into the center of the stopper nozzle 1 and the outer peripheral curved surface 71 at the tip of the stopper head 7. , And the molten metal is caused to flow down from the nozzle hole 12. The outer peripheral surface of the stopper nozzle is formed by a conical surface 11 whose diameter decreases upward,
The nozzle holder 72 made of iron plate is supported on the ladle main body 2 at a fixed position by driving a cotter pin 73 from outside the bottom surface 21. On the upper surface of the bottom surface 21, the base brick 3 is laid and arranged to form a base, and the nozzle receiving brick 4 in which the stopper nozzle 1 is fitted is disposed on the upper surface of the base brick 3.

The nozzle receiving brick 4 is formed of a stepped cylindrical body whose diameter is reduced upward by a step 42, and the inner surface side is provided with a fitting hole 41 having an inversely sloped surface compatible with the conical surface 11 of the stopper nozzle 1. The nozzle 1 is fitted. To illustrate the dimensional relationship, the bottom surface 21 of the ladle body 2 is 16 m thick.
m, made of an iron plate and having a thickness of 30 mm. The conical surface 11 of the stopper nozzle is 152 mm at the bottom and 1 mm at the top at the reduced diameter.
The nozzle receiving brick 4 is fitted into the fitting hole 41 of the nozzle receiving brick 4 with a slope of 30 mm, and the total height of the nozzle receiving brick 4 is 130 m.
m and a step 42 having a height of 25 mm in the horizontal direction is provided on the outer peripheral surface having a height of 80 mm from the top surface 44. Due to the setting of the step, the variation in the thickness of the nozzle receiving brick is constant in the circumferential direction R as illustrated in FIG. 2, and the thickness difference r1 / r2 in the vertical direction is 1: 0.9. Significantly reduce the partial difference in the total amount of thermal expansion.

[0015]

As described above, according to the present invention, the shape of the nozzle receiving brick is improved to a stepped cylindrical body, so that the wall thickness becomes almost uniform at any position, and the thermal shock caused by rapid heating is reduced over the entire circumference. And has an effect of minimizing cracks and cracks generated due to uneven expansion and contraction. In addition, since there is no corner like a square, the effect of stopping the local thermal stress in the adjacent refractory layer and also tending to spur the extension of the crack works,
For example, a record has been recorded that, in the past, the service life was exhausted after about 25 uses and a new one was used, but at least 50 times can be used reliably.

On the other hand, even in the work of ladle lining, when the refractory layer is formed by crushing irregular-shaped refractories, since the nozzle receiving brick has no angular corners and the entire boundary surface in contact therewith is circular, Since the strength and density can be evenly polished and the strength and density are evenly strengthened and the step 42 is embedded in the refractory layer, even if there is a gap at the boundary between the nozzle receiving brick outer peripheral surface and the refractory layer, the molten metal has a step The effect of blocking the course and preventing leakage of hot water is remarkable. Above all, in each process of tapping, receiving hot water, transporting and casting, the effect of wiping out the cause of a serious accident on safety, such as burns of workers and burnout of equipment due to molten metal leaking from the pouring port of the ladle. Difficult to replace with others.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing a main part of an embodiment of the present invention.

FIG. 2 is a plan view (A) and a front view (B) of a nozzle receiving brick of the same embodiment.

FIG. 3 is a front view (A) and a side view (B) of the entire bottom pouring ladle.

FIG. 4 is an overall vertical sectional front view schematically showing a conventional technique.

FIG. 5 is a longitudinal sectional front view showing a main part of a conventional technique.

FIG. 6 is a plan view (A) and a front view (B) of a conventional nozzle receiving brick.

FIG. 7 is a plan view (A) and a front view (B) of another conventional nozzle receiving brick.

FIG. 8 is a cross-sectional view of a main part of still another conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stopper nozzle 2 Ladle main body 3 Laying bottom brick 4 Nozzle receiving brick 5 Side wall brick 6 Fireproof layer 7 Stopper head 11 Conical surface 12 Nozzle hole 21 Bottom surface 22 Filling hole 41 Fitting hole 42 Step 43 Outer peripheral surface 44 Top surface

Continuation of the front page (56) References JP-A-63-119971 (JP, A) JP-A-59-174267 (JP, A) JP-A-8-117987 (JP, A) JP-A-1-80257 (JP) JP-A-9-314315 (JP, A) JP-A-7-68357 (JP, A) JP-A-56-66358 (JP, A) JP-A-59-49457 (JP, U) JP-A-59-49457 (JP, U) 5-13658 (JP, U) Japanese Utility Model Showa 56-45563 (JP, U) Japanese Utility Model 7-15152 (JP, U) Japanese Utility Model Showa 58-85463 (JP, U) Japanese Utility Model Utility Model 6-83146 (JP, U) U) Japanese Utility Model Showa 51-93813 (JP, U) Table 9-506299 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 41/50 520 B22D 11/10 320 B22D 41/02

Claims (1)

(57) [Claims] In a fireproof structure around a stopper nozzle of a bottom pouring ladle, a truncated conical stopper nozzle 1 to which a stopper head 7 suspended and raised and lowered is abutted is fixed on a bottom surface 21 of a ladle body 2. And the stopper nozzle 1
Fitting hole 4 having an inverted conical surface for internally fitting said conical surface 11
1 and a nozzle receiving brick 4 having an outer peripheral surface 43 whose diameter is reduced toward the upper side of the ladle with a step 42, and further from the bottom laying brick 3 laid on the bottom surface 21 to the nozzle receiving brick 4 A bottom-pouring ladle characterized in that a bottom surface from the outer peripheral surface 43 to the side wall brick 5 of the ladle is uniformly polished with an irregular refractory over a thickness reaching the top surface 44 to form a refractory layer 6. Fire-resistant structure around the stopper nozzle.