JP2009045654A - Method for execution work on tundish, and tundish - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress generation of metal penetration, by certainly holding castable refractory and further minimizing a crack generated in the castable refractory at a corner part. <P>SOLUTION: When applying castable refractory 12 on a corner part 22, an anchor block 13, which is reinforced with a core metal 26 and holds the castable refractory 12, is vertically immovably attached to an iron shell 10 of a tundish 3, which constitutes the corner part 22. A flange 21 extending inward to hold down the castable refractory from the upside is attached to the upper edge side of the iron shell 10 of the corner part 22. An outer peripheral edge 21b of a tip part 21a of the flange 21 is formed into a curved shape. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tundish construction method and a tundish.

Conventionally, in a continuous casting machine, the molten steel produced from a converter, secondary refining equipment, etc. is transported to the tundish by a ladle, and after the molten steel in the ladle is poured into the tundish, By supplying molten steel from the dish to the mold, the molten steel is continuously cast. The tundish provided in the continuous casting device is a solid refractory that is attached to the inside of the iron shell whose outer shell is box-shaped, and the amorphous refractory is attached to the solid refractory attached to the iron Generally, it is configured.
Solid refractories and irregular refractories used in tundish are thermally expanded when molten steel is poured into the tundish, and this thermal expansion causes the irregular refractory that comes into contact with the molten steel to rise upward or close. Try to put out.

For this reason, when constructing an amorphous refractory, the amorphous refractory is held against the iron skin or solid refractory in order to suppress the upward movement of the amorphous refractory and the movement of the refractory. An anchor block to be used, and a flange that holds the irregular refractory from above are used (for example, Patent Document 1).
The anchor block shown in Patent Document 1 is configured by connecting a rear anchor block located on the solid refractory side (iron skin side) and a front anchor block located on the irregular refractory side with a connecting metal fitting. ing. Further, Patent Document 1 discloses a flange that holds an irregular refractory from above.
Japanese Patent Laid-Open No. 9-4984

  In the anchor block of Patent Document 1, since the anchor block has a structure in which two members of the front anchor block and the rear anchor block are connected by a connecting metal fitting, the anchor block is large due to thermal expansion of an amorphous refractory. When stress is applied, the anchor block may be cracked, cracked, or chipped. As a result, the anchor block cannot hold the irregular refractory, the irregular refractory peels off from the solid refractory, and a cavity is formed between the solid refractory and the irregular refractory, It was a factor causing cracks in the inside and upper part of the amorphous refractory.

In addition, in the anchor block mounting structure disclosed in Patent Document 1, the anchor block moves upward, and this also forms a cavity, and cracks are generated in the inside and upper part of the amorphous refractory. It was a factor of letting go.
In addition to this, although the flange of Patent Document 1 can hold the amorphous refractory from the upper side, a crack may occur in the upper part of the amorphous refractory.
As described above, when the amorphous refractory is peeled off (when the cavity is formed), the molten steel flows into the cavity through the cracks inside and above, and this molten steel may reach the iron skin. is there. When the molten steel reaches the hollow portion or the iron skin, a metal bar is generated.

  Therefore, in the present invention, a tundish construction method capable of reliably holding an irregular refractory and suppressing the occurrence of a bare metal by minimizing cracks in the irregular refractory in the corner portion. And to provide tundish.

In order to achieve the above object, the present invention has taken the following measures.
The technical means of the present invention is a tundish construction method for constructing an irregular refractory on a convex corner inside a tundish, and when constructing the irregular refractory on the corner, An anchor block that holds an irregular refractory and is reinforced with a core metal is attached so as not to move up and down with respect to the iron skin of the tundish that constitutes the corner portion, and is attached to the upper end side of the iron skin of the corner portion. A flange that protrudes inward so as to hold the fixed refractory from above is attached, and the outer peripheral edge of the tip of the flange is curved.

Another technical means of the present invention includes an iron skin formed in a shape for storing molten steel, a solid refractory attached to the iron skin, an amorphous refractory applied to the solid refractory, and In a tundish provided with an anchor block that holds an irregular refractory and a flange that is provided on the iron skin and restricts the vertical movement of the irregular refractory, the anchor block is reinforced by a metal core and has a convex shape. The outer peripheral edge of the front end portion of the flange in the corner portion is in a curved shape.
First, the inventor verified the influence of the expansion of the amorphous refractory in the convex corner portion of the tundish. As a result, in the convex corner portion of the tundish, both one (one surface side) amorphous refractory and the other (other surface side) amorphous refractory arranged in the corner portion expand. Therefore, it has been found that the unshaped refractory tries to move upward along the corner portion or tries to protrude inward in a plan view.

In order to prevent both the unshaped refractory from being pushed up and pushed out, an anchor block for holding the unshaped refractory is provided at the corner of the tundish, and a flange is provided at the corner. I decided to provide it.
In addition, if the anchor block is cracked, cracked, or chipped, it will not be possible to hold the irregular refractory at the corner, and a bullion will be generated. Therefore, a metal core is provided in the anchor block to reinforce the anchor block. It was to be.
In addition, the inventor decided to make the anchor block immovable up and down because moving the anchor block after attaching it to the iron skin would cause the formation of a cavity and a crack.

  Furthermore, the inventor decided to prevent cracking of the upper part of the amorphous refractory by the flange by making various verifications on the shape of the flange and making the outer peripheral edge of the tip of the flange a curved shape.

  According to the tundish construction method and tundish of the present invention, the retention of the irregular refractory can be ensured and the crack of the irregular refractory can be kept to a minimum, thereby suppressing the occurrence of a metal bar. Can now.

The tundish construction method and tundish of the present invention will be described.
1 and 2 show a tundish of the present invention. This tundish is provided in a continuous casting apparatus that performs continuous casting of molten steel.
First, a continuous casting apparatus and a tundish will be described.
As shown in FIG. 12, the continuous casting apparatus 1 includes a tundish 3 for temporarily storing molten steel 2, a mold 4 to which the molten steel 2 from the tundish 3 is supplied, and a cast molded by the mold 4. A plurality of support rolls 5 for pulling out the piece and supporting the cast piece are provided.

The tundish 3 is provided with an immersion nozzle 7 through an injection port 9. The immersion nozzle 7 can be opened and closed by a slide valve 8, and the injection of the molten steel 2 into the mold 4 by the tundish 3 can be stopped or restarted by opening and closing the slide valve 8.
In the continuous casting apparatus 1, the molten steel 2 produced from the converter, secondary refining equipment, etc. is transported to the tundish 3 by the ladle, and the molten steel 2 in the transported ladle is poured into the tundish 3 and then slided. While the valve 8 is opened, the molten steel 2 in the mold 4 can be stirred to continuously cast the molten steel 2. In this continuous casting apparatus 1, several molten steels 2 of the same steel type can be continuously cast by several charges, or molten steels 2 of different steel types can be continuously cast.

As shown in FIGS. 1 and 2, the tundish 3 is formed in a substantially U shape in plan view. The tundish 3 includes an iron skin 10 formed in a bottomed box shape, a plurality of solid refractories (refractory bricks) 11 attached to the inside of the iron skin 10, and a solid refractory 11. An irregular amorphous refractory 12 is provided, and an anchor block 13 that holds the irregular refractory 12 so as to be immovable with respect to the iron shell or the solid refractory.
In the description of the iron skin 10 shown below, for the sake of convenience of explanation, the lower side of the paper surface of FIG. 1 is the front side, the upper side is the rear side, and the left and right sides of the paper surface of FIG.

  The iron skin 10 has a substantially U-shaped bottom wall 14 in plan view and an outer peripheral wall 15 rising from the outer periphery of the bottom wall 14. The outer peripheral wall 15 is located on the rear side of the bottom wall 14 and extends left and right, a pair of first side walls 17 extending from the left and right ends of the rear wall 16 to the front side, and from the front side of the first side wall 17. It has a pair of 1st front walls 18 extended right and left. The outer peripheral wall 15 has a pair of second side walls 19 extending rearward from the first front wall 18 at a position different from the first side wall 17 and a second front wall connecting the rear sides of the pair of second side walls 19. 20, flanges (regulators) 21 projecting (projecting) inward from the respective upper ends of the rear wall 16, the first side wall 17, the first front wall 18, the second side wall 19 and the second front wall 20. Have.

The solid refractory 11 is attached to substantially the entire inner surface of the bottom wall 14, the first front wall 18, the first side wall 17, the second side wall 19, the second front wall 20, and the rear wall 16. In this way, the irregular refractory 12 is applied to the surface of the fixed refractory 11 so as to cover the fixed refractory 11 attached to the inside of the iron skin 10.
As shown in FIGS. 1 to 4, the flange 21 in the two convex corner portions 22 constituted by the first side wall 17 and the second front wall 20 has a circular shape in plan view. Specifically, the outer peripheral edge 21b of the front end portion 21a of the flange 22 has a curved shape, and the front end portion 21a protrudes 210 mm (FIG. 4, L1) from the upper end side to the inner side. ing. In other words, the outer peripheral edge 21 of the distal end portion 21 of the flange 21 in the corner portion 22 is in a state in which there is no corner E to be described later (hereinafter, sometimes referred to as no corner), and the distal end portion 21a is an indeterminate refractory. It overlaps with.

A plurality of (for example, three) anchor blocks 13 are attached to the corner portion 22 via fixing brackets 24 at intervals in the vertical direction. An irregular refractory 12 is applied around the anchor block 13. In the corner portion 22, the anchor block 13 is disposed directly below the tip end portion 21 a of the flange 21.
The anchor block 13 is formed by molding an alumina-based amorphous refractory 12 containing at least 60% Al ₂ O ₃ and 30% SiO ₂ .
As shown in FIGS. 5 to 8, the anchor block 13 includes an anchor block main body 25 that holds the amorphous refractory 12 and a core metal 26 embedded in the anchor block main body 25.

The anchor block main body 25 is composed of a pedestal portion 30 attached to the fixture 24 in a cubic shape and a holding portion 31 that is cylindrical and mainly holds the amorphous refractory 12. The outer peripheral surface of the holding portion 31 is formed with unevenness, and the movement of the amorphous refractory 12 is restricted and held by this unevenness. The holding part 31 and the pedestal part 30 are integrally formed of an irregular refractory.
In this embodiment, the length, width, and width of the pedestal 30 are 143 mm × 143 mm × 59 mm, the outer diameter of the convex portion of the holding portion 31 is φ143 mm, and the outer diameter of the concave portion of the holding portion 31 is It is φ123mm. The interval between the convex and concave portions in the holding portion 31 is 20 mm.

The core metal 26 is used to reinforce the anchor block body 25, and is formed by combining a plurality of metal rods 33 (for example, round bars) in a cross or cross shape in front view or side view. Is.
The metal core 26 is integrated with the anchor block main body 25 by positioning the metal core 26 (rod body) inside the anchor block main body 25 (in other words, embedded) when the anchor block 13 is formed. . As described above, when the cored bar 26 is embedded and integrated in the anchor block main body 25, the outer peripheral part of the anchor block main body 25, that is, the outer periphery of the holding part 31 or the pedestal part 30, and the cored bar 26 (rod body). ) Is covered with an indeterminate refractory constituting the anchor block main body 25 so that the distance from the outer peripheral portion is 10 mm or more. In other words, in other words, the position (embedding position) of the cored bar 16 is set so that the distance D between the cored bar 26 and the outer peripheral portion of the anchor block body 25 is 10 mm or more.

As shown in FIGS. 5 and 6, when the cored bar 26 is shaped like a cross beam, at least two bars extending in the vertical direction (hereinafter, the vertical bars may be referred to as vertical bars) have a predetermined distance. Are separated from each other, and the two vertical bars 33a are connected by welding or the like with at least two bars 33b (hereinafter, the vertical bars may be referred to as horizontal bars) extending in the horizontal direction. Gold 26 is composed. The shortest distance between the rod 33 closest to the outer peripheral surface of the holding portion 31 of the anchor block main body 25 and the holding portion 31 is 10 mm or more.
As shown in FIGS. 7 and 8, when the metal core 26 has a cross shape, at least one vertical bar 33a is arranged, and the horizontal bar 33b is connected to the vertical bar 33a by welding or the like. Has been. The shortest distance between the rod 33 closest to the outer peripheral surface of the pedestal 30 of the anchor block body 25 and the pedestal 30 is 10 mm or more. In this embodiment, a rod 33 having a diameter of 9 mm is used.

The cored bar 26 is disposed inside the anchor block main body 25 so that a part of the rod 33 constituting the cored bar 26 extends from the holding part 31 to the pedestal part 30, and the holding part 31 and the pedestal part 30. It is arranged so as to straddle.
More specifically, as shown in FIGS. 5 and 7, when the anchor block main body 25 is attached to the fixing bracket 24, the fixing bracket 24 engages the anchor bracket main body 25 with the engaging portion (tip portion). 21a) A cored bar 26 (rod 33) is arranged in the anchor block main body 25 so as to pass a line L connecting 35.

Thereby, the boundary part of the holding | maintenance part 31 and the base part 30 can be indirectly reinforced from the inside of the anchor block main body 25, and the crack and the crack in a boundary part can be prevented or suppressed.
Unlike the indeterminate refractory that forms the anchor block 13, the fixing bracket 24 is made of metal or the like, and is formed in a substantially U shape in side view by connecting flat plates by bending or welding. The fixing bracket 24 is attached to the iron skin 10 by welding or the like, and an engagement portion 35 that is bent from the left and right or front and rear ends of the attachment portion 38 and engages with the pedestal portion 30 of the anchor block main body 25. And have.

In the tundish construction method of the present invention, first, the fixing bracket 24 is welded to the iron shell 10 by welding or the like so that the engaging portions 35 of the fixing bracket 24 are aligned vertically with respect to the corner portion 22 of the iron shell 10. Install. Then, the solid refractory 11 is pasted almost entirely on the inside of the bottom wall 14, the first front wall 18, the first side wall 17, the second side wall 19, the second front wall 20 and the rear wall 16 of the iron skin 10.
The upper and lower sides of the pedestal portion 30 of the anchor block main body 25 are engaged with the engaging portions 35 of the fixing bracket 24, and the anchor block main body 25 is attached to the fixing bracket 24 so that the vertical movement is impossible.
The amorphous refractory 12 is applied so as to cover the entire solid refractory 11 and the anchor block 13 attached to the inside of the iron skin 10. At this time, in the construction of the corner portion 22, the amorphous refractory 12 to be constructed is overlapped with the tip portion 21 a of the flange 21.

In summary, when the irregular refractory 12 is applied to the corner portion 22, the anchor block 13 that holds the irregular refractory 11 and has the cored bar 26 is connected to the tundish 3 that constitutes the corner portion 22. It attaches to the iron skin 10 so that it cannot move up and down.
Moreover, in the corner part 22, the amorphous refractory 12 is arrange | positioned under the edge of the front-end | tip part 21a becoming curvilinear.
After the construction of the tundish 3, the movement of the irregular refractory 12 that forms the inner wall of the tundish 3 is restricted and the amorphous refractory 12 is held in the corner portion 22 by the holding portion 31 of the anchor block main body 25. Will be. Further, the flange 21 holds the irregular refractory 12 when it is pushed up due to thermal expansion or the like.

  Table 1 shows an example after the tundish was used 200 times after the tundish was constructed by the tundish construction method of the present invention, and a construction method different from the tundish construction method of the present invention. The comparative example after using a tundish 200 times is summarized.

In the examples and comparative examples in Table 1, as shown in FIG. 10A, the fixing direction is “left and right”. The anchor block 13 (anchor block main body) is arranged so that the engaging portions 35 of the fixing bracket 24 are arranged side by side. 25) is fixed, and as shown in FIG. 10B, when the fixing direction is “up and down”, the anchor block body 25 is fixed so that the engaging portions 35 of the fixing bracket 24 are aligned vertically. It shows that it did.
In the examples and comparative examples in Table 1, the shape of the flange 21 is “trapezoid 1”, which is a trapezoid as shown in FIG. "Trapezoid 2" is a trapezoid as shown in FIG. The trapezoid 1 and the trapezoid 2 have different lengths in which the flange 21 overlaps the amorphous refractory 12, and the length L2 of the protruding portion of the trapezoid 1 is 110 mm. The length L3 of the protruding portion is 180 mm.

In Comparative Examples 1 and 2, as shown in FIG. 9, since the core metal 26 is not contained in the anchor block body 25, the strength of the anchor block body 25 is weak, and the refractory of the anchor block body 25 is cracked. The pedestal portion 30 and the holding portion 31 of the anchor block main body 25 have been divided.
Due to this influence, the anchor block main body 25 has moved upward (shifted upward) with the expansion force of the irregular refractory 12.
In addition, as shown in FIG. 11, in Comparative Examples 1 and 2, since the shape of the flange 21 at the corner portion 22 is trapezoidal, the amorphous refractory 12 is cracked by the trapezoidal corner E. Since it was in an easy state, it overlaps with the effect of shifting on the anchor block main body 25 described above, the crack at the upper part of the irregular refractory 12 becomes large (large crack), and the irregular refractory 12 is pushed upward or inside. A large cavity (gap) was formed between the fixed refractory 11 and the irregular refractory 12 by rushing to the front.

Therefore, in Comparative Examples 1 and 2, since the upper displacement of the anchor block main body 25, the crack size at the top of the irregular refractory 12 and the size of the hollow portion are large, a large scale metal insert was generated (the metal insert). , Yes (large)).
In Comparative Example 3, the shape of the flange 21 of the corner portion 22 has no corners, so that compared to Comparative Examples 1 and 2, the size of the crack in the upper part of the amorphous refractory 12 is slightly suppressed (small cracks). ) Further, in Comparative Examples 4 and 5, the anchor block main body 25 can be made difficult to shift upward by making the fixing direction of the anchor block main body 25 up and down compared to Comparative Examples 1 and 2.

In Comparative Examples 3 to 5, compared with Comparative Examples 1 and 2, the size of the hollow portion can be reduced by making the flange 21 have no corners or by making the anchor block body 25 fixed in the vertical direction. However, the influence of the division between the pedestal portion 30 and the holding portion 31 due to the absence of the cored bar 26 in the anchor block main body 25 was large, and a medium-sized bullion insert was generated (the bullion insert is present. (During)).
In Comparative Example 6, compared to Comparative Examples 1 and 2, the shape of the flange 21 was made square, and the fixing direction of the anchor block main body 25 was set up and down, but a medium-scale ingot was generated (ground) There is money (medium)).

In Comparative Examples 7 and 8, the core block 26 is inserted into the anchor block main body 25, so that the anchor block main body 25 is not divided. However, the flange 21 has a trapezoidal shape and is fixed in the left-right direction. Caused a medium-sized bullion bar (bulb bar, yes (medium)).
In the comparative example 9, since the core metal 26 is contained in the anchor block main body 25 and the shape of the flange 21 is also without a corner, the anchor block main body 25 is not divided, and the upper surface of the irregular refractory 12 is formed. Although there was almost no crack (small crack), the anchor block main body 25 was fixed in the left-right direction, and a slight upward shift occurred. As a result, a small bullion bar was generated (a bullion bar is present (small)).

In Comparative Examples 10 and 11, since the shape of the flange 21 is trapezoidal, a crack is generated on the upper surface of the irregular refractory 12 though it is very fine, and as a result, although it is a small scale, it is a bare metal holder. Occurred (bulk, yes (small)).
In the first embodiment, the core block 26 is contained in the anchor block main body 25, the flange 21 has no corner, and the anchor block main body 25 is fixed in the left-right direction. 25, no deviation of the anchor block body 25, and cracks on the upper surface of the irregular refractory 12 could be eliminated. Even in the size of the cavity between the fixed refractory 11 and the irregular refractory 12, it was possible to minimize the size of the cavity, not a size that would cause a problem metal insert. As a result of the above, no ingots were generated (ingots, none (small)).

As described above, the presence or absence of the cored bar 26 in the anchor block main body 25, the fixing direction of the anchor block main body 25 and the shape of the flange 21 are changed, thereby suppressing the upper displacement of the anchor block main body 25 or the indefinite shape. The magnitude | size of the crack of the upper surface of the refractory 12 can be made small, and the magnitude | size of a cavity part can be made small.
Table 2 summarizes the degree to which bullion is generated according to the number of times the tundish is used. In Table 2, “◯” indicates that no bullion is generated, “Δ” indicates that a bullion is occasionally generated, and “×” indicates that a bullion is generated.

As shown in Table 2, it was possible to find a condition that no bullion was generated even when the tundish was used at least 200 times.
The present invention is not limited to the above embodiment.

It is a top view of a tundish. It is sectional drawing of a tundish. It is a front view at the time of attaching an anchor block. It is the enlarged plan view which expanded the flange of the corner part. It is a side view which shows a cross-shaped cored bar. It is a top view which shows a cross-beam-shaped metal core. It is a side view which shows a cross-shaped metal core. It is a top view which shows a cross-shaped metal core. It is a figure which shows the crack of the anchor block main body, a crack, and a chip. It is a figure which shows the fixing direction of an anchor block. It is a top view which shows the shape of a flange, the crack of the amorphous refractory of a corner part, etc. It is a block diagram of a continuous casting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous casting apparatus 2 Molten steel 3 Tundish 4 Mold 10 Iron skin 11 Solid refractory 12 Indeterminate refractory 13 Anchor block 21 Flange 22 Corner part 24 Fixing bracket 25 Anchor block main body 26 Core metal 31 Holding part 33 Rod 33a Vertical bar 33b Horizontal bar 35 Engagement part 38 Attachment part

Claims (2)

In the tundish construction method of constructing an irregular refractory on the convex corner inside the tundish,
When the irregular refractory is applied to the corner portion, the anchor block that holds the irregular refractory and is reinforced by a cored bar is moved up and down with respect to the iron shell of the tundish constituting the corner portion. Mounted immovable,
A flange that protrudes inward so as to hold the irregular refractory from above is attached to the upper end side of the iron skin of the corner portion, and the outer peripheral edge of the front end portion of the flange has a curved shape. Dish construction method. An iron skin formed in a shape for storing molten steel, a solid refractory attached to the iron skin, an irregular refractory applied to the solid refractory, and an anchor block for holding the irregular refractory In the tundish provided with the flange that is provided on the iron skin and regulates the vertical movement of the irregular refractory,
The anchor block is reinforced by a cored bar and attached to an iron shell that forms a convex corner portion so as not to move up and down, and the outer peripheral edge of the front end portion of the flange in the corner portion is curved. Tundish characterized by that.

Images