JP2000160224A - Slag holding and shutting off tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a slag holding and shutting off tool which can surely cut the slag in a molten steel tapping process from a converter and can simply manufacture and can prevent the erosion. SOLUTION: In this slag holding and shutting-off tool 10 which has a head part 1 and a foot part 12 connected to the head part and by which the foot part 12 is inserted into a steel tapping hole in the converter at the using time to shut off the steel tapping hole from the inside by the head part 11, the upper part of the foot part 12 is provided with a diameter expanding part 21 abutting on the lower end part of the head part 11 and smoothly connected to the head part 11. The area in the end surface of the diameter expanding part 21 has 2-16 times of the cross sectional area of the bar-like foot part body 20 at the lower position than the diameter expanding part 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slag holding and closing device used to prevent slag from flowing out together with molten metal at the end of tapping from a converter.

[0002]

2. Description of the Related Art Slag having a lower specific gravity than molten steel floats above the molten steel in a converter. Since the reaction of the ladle lining causes a problem such as shortening of the life of the ladle, it is necessary to close the tap hole before tapping the slag from the converter and to output only molten steel. The operation of preventing slag outflow during converter tapping is generally called slag cutting, and this slag cutting is an important measure as a manufacturing cost and quality improvement measure. Conventionally, as a measure, to close the tapping port while holding the slag in the converter, a spherical closure with a bulk specific gravity adjusted to float between the molten steel and the slag layer above it was used. Was.
That is, the spherical closure is suspended inside the converter at the time of tapping, and at the end of the flow of molten steel, the spherical closure is brought into close contact with the tapping outlet to stop the outflow of slag.

[0003]

However, the conventional spherical closure has a problem in that the exit of the tapping port is unstable because the floating position is not constant unless the vortex is introduced into the molten steel. there were. Therefore, as a result of earnest research, the present inventor has developed a slag holding / closing tool 51 having a specific gravity of preferably 3 to 4.5, as shown in FIG. The slag holding and closing member 51 includes a head 52 made of a castable refractory and a bar-shaped foot 50 integrally connected to a lower portion thereof. Are vertically penetrated, and a specific gravity adjusting weight 54 is embedded in the head 52. In use, the specific gravity is adjusted so that the head 52 floats between the slag layer and the molten steel, and the feet 50 hang under the head 52 and are located in the molten steel. When the molten steel flows toward the tap hole of the converter in the process of ending the discharge of the molten steel, the foot 50 receives the flow of the molten steel, and the entire slag holding and closing member 51 is drawn to the tap hole of the converter. Thus, the tapping port can be stably closed. However, since the slag holding / closing member 51 is an integral part of the head portion 52 and the foot portion 50, if the slag holding / closing member 51 is formed by integrally casting the slag holding / closing member 51, the weight of the product is large, and it takes time to manufacture. Take it. Therefore, when the slag holding / closing member 51 is divided into two parts by, for example, the dividing line 55 and casting is performed, and then assembly is performed, the following problems occur. (1) Since the sectional area at the dividing line 55 is small, the bending strength of the foot portion 50 after assembly is small. (2) Molten steel invaded from the joint surfaces of the upper and lower members after assembly, and the foot 50 fell off due to erosion. (3) Since the distance from the outer periphery of the foot part 50 to the core material 53 is small, the erosion of (2) is likely to occur. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a slag holding closure that can be reliably cut in a step of tapping steel from a converter, can be easily manufactured, and can prevent erosion. I do.

[0004]

According to the present invention, there is provided a slag holding / closing tool according to the present invention, which has a head and a foot connected thereto, and in use, the foot is used for a converter. A slag holding closure that fits into the tapping hole and has the head closing the tapping port from the inside, the upper part of the foot abutting against the lower end of the head, And the area of the end face of the enlarged diameter portion is in the range of 2 to 16 times the cross-sectional area of the rod-shaped foot body located below the enlarged diameter portion. With the feet, the feet can be suspended in the molten steel flowing from the head floating between the molten steel and the slag, thereby moving following the flow of the molten steel. In addition, since the area of the end face of the enlarged diameter portion connected to the head is in a range of 2 times or more and 16 times or less of the sectional area of the foot body,
The strength at the time of connection is increased. If it is smaller than 2 times, the strength may be insufficient and it may be broken. If it is larger than 16 times, the foot may be smaller than the head, and the head may be smoothly guided to the tap hole. become unable. The range is desirably 3 times or more and 9 times or less. If it is 3 times or more, the strength can be increased, and if it is 9 times or less, the head can be guided more smoothly to the tapping port.

The enlarged diameter portion has an inverted truncated cone shape and is smoothly joined integrally to the lower leg body, and a connecting portion between the enlarged diameter portion and the head has a sealing material. It may be filled. Here, for the sealing material, for example, fire-resistant mortar can be used, and materials such as chamotte, alumina, carbon, silicon carbide, zirconia, and chromium oxide are selectively used according to specific gravity, heat resistance, and price. Good. Since the connection is made via the seal material, intrusion of molten steel from the connection portion can be prevented. Also, the head and the foot may be provided with first and second core members connected by screws or bayonet, respectively. Mechanical strength can be increased by screws or bayonet.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

As shown in FIGS. 1 and 3, a slag holding and closing tool 10 according to an embodiment of the present invention is connected to a head 11 larger than a tapping port 32 of a converter 28 and a lower part of the head 11. It has a bar-shaped foot 12 to be formed. The head 11 has a first core material 13 covered with an exterior part 14 made of a castable refractory. The first core material 13 has a female screw part 15 formed in a lower part, and a specific gravity adjusting weight 17 is formed in the center. It is fixed. It is to be noted that a deformed steel bar may be used instead of the first core material 13 made of a reinforcing bar. By using the deformed bar, the strength of the contact surface with the exterior part 14 can be increased.
The shape of the exterior portion 14 is a substantially inverted truncated cone shape, and the side surface is a gentle curved surface bulging outward. A first core material 13 is provided so as to protrude from an upper portion of the exterior part 14, and the first core material 13 is provided.
A hole corresponding to the diameter of the second core member 18 is provided at a lower portion of the fourth member 4 so as to communicate with the female screw portion 15. Since the first core material 13 protrudes from the upper part of the exterior part 14, when the slag holding / closing tool 10 is charged into the converter 28, the slag holding / closing tool 10 can be lifted with the charging device sandwiching the protruding part 16. . Since the projecting portion 16 made of a reinforcing bar is inserted between the slag holding closures 10, it is possible to prevent the castable refractory on the side of the slag holding and closing tool 10 from directly being damaged.

The foot 12 is provided with a second core 18 made of a reinforcing bar.
And an exterior part 19 covered with a castable refractory. The exterior part 19 is formed integrally with a column-shaped foot main body 20 and an upper part thereof, abuts on a lower end of the head 11, and smoothly contacts the head 11. Has an enlarged-diameter portion 21 connected to the main body. Also, the enlarged diameter portion 2
1 has an inverted truncated cone shape and is smoothly and integrally joined to a foot main body 20 located below the enlarged diameter portion 21. As the second core member 18, a round bar of a reinforcing bar is used, but a deformed bar may be used. The area of the end face of the enlarged diameter portion 21 (determined from the diameter D2) is not less than twice and not more than 16 times the cross-sectional area (determined from the diameter D1) of the rod-shaped foot body 20 located below the enlarged diameter portion 21 (preferably). (3 times or more and 9 times or less), thereby increasing the bending strength of the joint portion (connection portion). A second core material 18 is provided to protrude from an upper portion of the foot portion 12, and a male screw portion 22 is provided at a tip portion thereof. A sealing material 23 is filled between the head 11 and the foot 12 and is connected to the female thread 15 of the first core 13 and the male thread 22 of the second core 18 provided respectively. In addition, the nut can be welded without the female screw portion 15, or can be connected with a bayonet instead of the screw (the female screw portion 15, the male screw portion 22). If it is a bayonet, it can be installed more easily. The specific gravity of the slag holding closure 10 is adjusted to a range smaller than the molten steel 30 and larger than the slag 29. The adjustment can be easily performed by changing the size of the specific gravity adjusting weight 17.

Next, a manufacturing method will be described. As shown in FIG. 2, when the foot 12 is manufactured, the molds 24, 2
Use 5 A hole corresponding to the diameter of the second core material 18 is provided in a lower portion of the mold 25, and a hole 26 is also provided in a floor portion below the hole. When performing casting, first, mold 2
The second core material 18 is inserted into the fourth and the 25th with the male screw portion 22 facing down. Male screw part 22 protruding from hole of mold 25
Is held upright by a hole 26 provided in the floor. Then, a castable refractory material is poured into the mold interior 27 from above, cured, deframed, and further dried to complete the foot portion 12. The reason why the casting is performed with the enlarged diameter portion 21 down is to cast the end face of the enlarged diameter portion 21 flat. Although not shown, when casting the head 11, the feet 12
It is preferable to make the lower end portion contacting the lower side downward. Since the head 11 and the feet 12 are separately cast, the mold can be reduced in size and can be manufactured easily. As shown in FIG. 1, the completed head 11
And the foot 12 is screwed via the sealing material 23. The mechanical strength is increased by screwing, and the infiltration of the molten steel 30 from the side is prevented by the sealing material 23.

Next, the state in use will be described. FIG. 3 (A)
As shown in the figure, at the end of tapping from the converter 28, the slag holding and closing tool 10 is charged into the converter 28 by a charging device (not shown). The first core material 13 is provided on the upper part of the slag holding closure 10.
Is projected to form the protruding portion 16. By holding the protruding portion 16, it is possible to easily insert the refractory while preventing breakage of the outer refractory. Since the specific gravity of the slag holding and closing tool 10 is adjusted to a range larger than the slag 29 and smaller than the molten steel 30, the head 11 of the slag holding and closing tool 10 is fixed to the slag 2
9 and the molten steel 30, the feet 12 are immersed in the molten steel 30.

The upper part of the slag holding and closing device 10 is
9, the first core material 13 made of rebar is not melted away, and the joint between the head 11 and the foot 12 is protected by the sealing material 23. There is no possibility that the molten steel 30 enters and the inside is melted. The second core 18 (see FIG. 1) at the lower end 31 of the foot 12 is in contact with the molten steel 30. However, since the cross-sectional area of the second core 18 is small, erosion does not progress. Absent. But,
If erosion is likely to proceed, the second core 18
Can be covered with a refractory material. Since the enlarged diameter portion 21 of the slag holding closure 10 is smoothly connected to the head 11, the fluidity of the molten steel 30 when passing through the side of the slag holding closure 10 is improved. Since the fluidity is improved, erosion can be prevented without imposing a load on the sealing material 23.

At the time of tapping, the molten steel 30 flows toward the tapping port 32, but the slag 29 is suspended in a layer above the molten steel 30 and does not flow. The conventional spherical closure is a slag 2
Since it floats between the molten steel 9 and the molten steel 30, even if it attempts to flow following the molten steel 30, it is obstructed by the slag 29 that does not flow, and it has been difficult to perform a reliable operation. The inventor of the present application pays attention to the fluidity of the molten steel 30, and in order to make the slag holding and closing tool follow this flow, the slag holding and closing tool 1 is used.
The foot 12 was provided at the lower part of 0. The slag holding closure 10 is drawn to the tapping port 32 by the flow inside the molten steel 30 by the feet 12. Then, as shown in FIG. 3 (B), when the tapping of the molten steel 30 is completed, the foot portion 12 is fitted into the tapping port 32 of the converter 28, and the head 11 closes the tapping port 32 from the inside, so that the tapping is reliably performed. Next, the tapping port 32 is closed.

Although the present invention has been described based on one embodiment, the present invention is not limited to the above-described embodiment. For example, the first core material and the second core material may be used. The cross-sectional shape may be other than a circle, and the cross-sectional shape of the foot may also be a square, a triangle, a hexagon, an octagon, or the like. Further, the first core member provided to protrude from the upper part of the head may be bent at its tip into a U-shape. When being charged into the converter by the charging device, the U-shaped tip is hung and lifted, so that handling is simplified. Further, the top of the first core material may be enlarged in diameter to form a hook of the gripper.

[0014]

EXAMPLE In the example using the slag holding closure according to the above embodiment, the number of slag cutting failures was 0/20. On the other hand, a comparative example in which a straight foot and a head were joined by screws without using a sealing material (partition line 5 in FIG. 4).
In the case of assembling the upper and lower members divided by 5, the number of failures was 5/20. In the comparative example, it was confirmed that the feet were broken and dropped in the converter. It is considered that the reason for this was that erosion progressed from the seam between the head and the foot because no seal material was used, and the area of the joint between the foot and the head was smaller than the cross-sectional area of the foot. It is considered that the use of the same material shortened the distance from the molten steel to the core material, and further accelerated the progress of erosion. It is also conceivable that when the foot portion was subjected to a lateral force from the molten steel, the joint portion was broken due to insufficient mechanical strength. In the example, since the number of failures was 0, it is considered that there was an effect of preventing the erosion by increasing the area of the joint and using the sealing material.

[0015]

In the slag holding closure according to the first to third aspects, the foot and the head are connected and are not manufactured integrally, so that the manufacture can be simplified. Further, since the area of the end face of the enlarged diameter portion connected to the head is in the range of 2 to 16 times the cross-sectional area of the foot main body, the mechanical strength at the time of connection is increased. Furthermore, since the distance from the outer periphery of the end face to the core material when connected is increased, erosion is less likely to occur, and the slag can be reliably cut by preventing the feet from falling. In particular, in the slag holding closure according to the second aspect, since the sealing material is used, intrusion of molten steel from the connected portion can be prevented, and the foot can be prevented from dropping during use. . In the slag holding closure according to the third aspect, the head and the foot are provided with the first and second core members connected by screws or bayonet, respectively, so that the mechanical strength is increased and the slag is kept stable. It can be stored and can prevent the feet from falling during use.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a slag holding and closing device according to an embodiment of the present invention.

FIG. 2 is a front sectional view of the foot portion during manufacture.

FIGS. 3A and 3B are explanatory diagrams showing the same use state.

FIG. 4 is a front sectional view of a slag holding and closing device according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Slug holding closure 11 Head 12 Foot 13 First core material 14 Exterior part 15 Female screw part 16 Projection part 17 Specific gravity adjustment weight 18 Second core material 19 Exterior part 20 Foot part main body 21 Large diameter part 22 Male screw part Reference Signs List 23 sealing material 24 mold 25 mold 26 hole 27 inside of mold 28 converter 29 slag 30 molten steel 31 lower end 32 tapping outlet

Claims (3)

[Claims] 1. A head having a head and a foot connected thereto,
In use, the foot is fitted into the tapping hole of the converter, and the head is a slag holding and closing tool that closes the tapping port from the inside. An enlarged diameter portion which abuts on a lower end portion of the head and smoothly connects to the head, wherein an area of an end face of the enlarged diameter portion is cut off of a rod-shaped foot body located below the enlarged diameter portion. A slag holding and closing device characterized by being in a range of 2 times to 16 times the area. 2. The slag holding and closing device according to claim 1, wherein the enlarged diameter portion has an inverted truncated cone shape and is smoothly joined integrally to the lower leg body. A slag holding / closing tool, wherein a connecting part with a head is filled with a sealing material. 3. The slag holding and closing device according to claim 1, wherein the head and the foot are provided with first and second core members connected by screws or bayonet, respectively. A slag holding and closing device characterized by the above-mentioned.