JP2003305543A - Mold for continuous casting of steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for continuous casting, which can prevent crack of a cast piece without causing such large contact pressure that causes the crack of the cast piece between a coagulated shell and the mold in a lower region of the mold, and can elongate the life of the mold, and can prevent development of a rhohmbus deformation when it has been produced. <P>SOLUTION: The mold for continuous casting of steel is characterized in that the mold is provided with longitudinal grooves at the corners inside the mold so as to form air gaps between the corner portions and their neighboring portions over the range from the position below the molten steel level in the mold by at least 500 mm to the exit end of the mold, and the width of the longitudinal grooves is not larger than 1/3 of the length of one side of the inner surface of the mold. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mold for continuous casting of steel.

[0002]

2. Description of the Related Art In continuous casting of steel, a continuous casting mold (the continuous casting mold means a so-called "tube mold")
Inside, the poured molten steel contacts the inner surface of the mold and is cooled to form a thin solidified shell, and eventually solidifies and shrinks with the temperature drop of the solidified shell, and tries to separate from the inner surface of the mold. Then, by moving downward, the solidified shell flat surface (cast slab flat surface) contacts the inner surface of the mold due to bulging due to the static pressure of molten steel, while the solidified shell corner portion (slab slab corner) that is not affected by bulging is the mold It remains detached from the inner surface. Due to this, unevenness occurs in the growth of the solidified shell between the flat surface portion and the corner portion, and so-called rhombus deformation occurs in the slab along with the growth of the solidified shell due to the uneven solidification strain. become. In particular, it is known that in a continuous casting mold for a billet having a small cross section (60 mm square to 300 mm square), a gap is likely to be formed between the solidified shell corner portion and the mold inner surface.

Once the rhomboidal deformation occurs, the sharp-angled solidified shell corner portion grows further by making good contact with the inner surface of the mold, while the obtuse-shaped solidified shell corner portion is formed between the inner surface of the mold and the mold. The formation of the gap causes more delay in solidification. This uneven growth of the solidified shell further promotes rhombic deformation. When the rhombic deformation proceeds beyond the allowable range in this way, as shown in FIG. 12, an extremely large contact pressure is generated between the sharpened solidified shell corner and its vicinity and the mold (FIG. 12 (b)). This causes cracks in the slab, and shortens the mold life remarkably. When the rhombic deformation becomes more remarkable, breakout may occur. FIG. 1
2A and 2B are diagrams schematically showing a state in which a slab is deformed in a conventional continuous casting mold, in which (a) is a cross-sectional view and (b) is an acute angle in (a). It is a figure for demonstrating the contact pressure in the solidification shell part which makes a shape. In FIG. 12B, the length of the arrow indicates the magnitude of contact pressure.

Conventionally, as a continuous casting mold in which a solidification delay at the corner portion is unlikely to occur, a continuous casting mold having a multi-step taper which is divided into a plurality of steps in the casting direction (cast piece drawing direction) and the taper amount is changed at each step, , A continuous casting mold having a parabolic taper (curved taper) has been put into practical use.

However, in such a multi-step taper continuous casting mold or a parabolic taper continuous casting mold, the solidified shell grows well in the upper part of the mold and the slab temperature decreases accordingly, so in the lower part of the mold. However, there is a problem that a large contact pressure is generated between the corner of the solidified shell and its vicinity and the mold. This large contact pressure between the solidified shell and the mold reduces wear on the inner surface of the mold to shorten the mold life, and a large force acts on the surface of the slab to restrain the slab in the mold, causing slab cracking. There was a problem that it occurred. As described above, there has been a dilemma that "the more the solidified shell is formed, the more serious this defect is."

Conventionally, various proposals have been made to eliminate the above-mentioned problems due to the contact pressure between the corner of the solidified shell and its vicinity and the mold. For example, JP-A-200
In 0-79445, the cross-sectional shape of the mold is a quadrangle in which four straight sides are connected by four quarter arcs,
A mold for continuous casting of steel has been proposed in which the inner peripheral length is large on the upper end side of the mold and small on the lower end side, and the inner peripheral length of the mold is changed by the taper amount of the mold and the radius of the quarter arc. (Prior art 1). The mold of the prior art 1 has a corner portion in the mold composed of a quarter arc radius portion so as to match the outer peripheral length of the slab to be solidified so as to maintain the contact state between the mold and the solidified shell over the entire area of the mold. The radius of the arc is gradually reduced toward the lower end of the mold.

Further, the prior art 2 is characterized in that in the lower region of the mold, the taper amount of the corner portion in the casting direction is set to zero and the cross-sectional shape is formed by connecting the corner portion and the side portion with a smooth curve. Molds for continuous casting of steel are known.

However, in the continuous casting mold of the prior art 1, the contact pressure between the corner of the solidified shell and the mold can be reduced in the lower region of the mold, but the straight side portion near the corner of the solidified shell is reduced. It was not possible to reduce the contact pressure at.

Further, in the continuous casting mold of the prior art 2, the contact pressure between the corner of the solidified shell and its vicinity and the mold can be lowered in the lower region of the mold to reduce the contact pressure, but a diamond is formed on the slab. When the deformation occurs, there are problems as described below.

In order to prevent the occurrence of rhombus deformation, a taper is provided to prevent an air gap (a gap generated between the mold and the solidified shell) over the entire mold, and the ideal shape of the inner surface of the mold is "constant". It exists only with "steel grade composition, constant casting speed, constant molten steel temperature, and constant molten metal level". Since it is difficult to keep these conditions constant in actual operation, it is extremely difficult to completely eliminate the air gap that occurs during the solidification process of molten steel even with continuous casting molds that have the ideal inner shape of the mold. is there. That is, it is extremely difficult to surely prevent the diamond-shaped deformation of the cast piece due to the solidification delay of the solidified shell corner portion.

As described above, the continuous casting mold of Prior Art 2 has a structure in which the taper amount in the casting direction of the corner portion of the inner surface of the mold is zero in the lower region of the mold. However, in the mold of this Prior Art 2, the amount of retreat of the mold inner surface corner portion with respect to the cast piece corner portion (solidified shell corner portion) is small, and when rhombus deformation occurs in the cast piece, it becomes an acute angled solidified shell corner portion. There is a problem that a corner portion in the mold comes into contact with each other, and as shown in FIG. 13, a large contact pressure is generated between the corner portion of the solidified shell and its vicinity and the mold. In addition, in FIG.
[Fig. 6] is a diagram schematically showing a situation in which rhombus deformation occurs in a slab in a continuous casting mold of Prior Art 2, in which (a) is a cross-sectional view and (b) is (a). It is a figure for demonstrating the contact pressure in the solidification shell part which makes an acute angle. The length of the arrow in FIG. 13B indicates the magnitude of contact pressure.

Therefore, the present invention solves the above-mentioned problems of the prior art, and does not generate a large contact pressure between the solidified shell and the mold in the lower region of the mold so as to prevent the slab from breaking. It is intended to provide a mold for continuous casting of steel, which is capable of preventing the above, and can prolong the life of the mold, and can also prevent the promotion of the slab rhomboidal deformation when it occurs. Is.

[0013]

In order to achieve the above object, the present invention has the following constitution.

According to a first aspect of the present invention, in a mold for continuous casting of steel, at least 5 parts below the molten steel level in the mold.
A vertical groove for forming an air gap between the corner of the solidification shell and its vicinity is provided at a corner in the mold from a position exceeding 0 mm to the mold exit end.
The width of the vertical groove is ⅓ or less of the length of one side of the inner surface of the mold at the outlet end of the mold, which is a mold for continuous casting of steel.

According to a second aspect of the present invention, in the continuous casting mold for steel according to the first aspect, when the continuous casting mold is for a vertical bending type continuous casting facility, it is connected to the outer curved surface of the slab. The vertical groove is provided at two corners on the inner surface side of the mold.

According to a third aspect of the present invention, in the continuous casting mold for steel according to the first aspect, in the case where the continuous casting mold is for a curved continuous casting equipment, the inner side of the curved surface inside the mold is located. The vertical groove is provided at two corners.

According to a fourth aspect of the present invention, in the steel continuous casting mold according to the first, second or third aspect, an expansion portion for expanding the vertical groove in the width direction is provided at the mold outlet end. To do.

According to the mold for continuous casting of steel according to the present invention, a vertical groove for forming an air gap between the corner of the solidified shell and its vicinity is formed in the corner of the mold in the lower region of the mold. Since the vertical groove is provided, it is possible to avoid contact between the mold and the corner of the solidified shell and its vicinity. As a result, a large contact pressure that causes slab cracking between the solidified shell and the mold is not generated in the lower region of the mold, slab cracking can be prevented, and the life of the mold can be extended. When the slab rhombus deformation occurs, it is possible to prevent its promotion.

The continuous casting mold according to the present invention has vertical grooves provided at the corners in the mold in the lower region of the mold. Then, in the case of a perfectly vertical continuous casting facility that is well maintained, the cast pieces (solidified shells) are evenly pressed against the four inner surfaces of the mold. Therefore, in the continuous casting mold according to the present invention, which is applied to the complete vertical type continuous casting equipment, it is preferable to provide vertical grooves at the four corners in the mold in the lower region of the mold.

Further, in the case of a curved type continuous casting equipment, due to the arrangement of the cast piece drawing apparatus, the cast piece (solidified shell) is pressed against the inner curved surface in the mold, and conversely, the outer side in the mold. The curved surface is on the side of separation. Therefore, the contact pressure generated between the solidified shell and the mold in the lower region of the mold is larger on the inner curved surface than on the outer curved surface. Since the weight of the mold and the cast piece connected to the lower part of the mold contributes to the force to pull out the cast piece along the mold curvature from the mold, in the case where the equipment curvature radius is large, the inside curved surface in the mold is The tendency of the slab (solidified shell) to be pressed is reduced. On the other hand, if the equipment bending radius is small, the tendency of the cast piece (solidified shell) to be pressed against the inward curved surface becomes remarkable. Therefore, in the continuous casting mold according to the present invention, which is applied to the curved type continuous casting equipment, it is preferable to provide the vertical groove in the two corner portions on the inner curved surface side in the mold in the lower region of the mold. There is.

Further, in the case of a vertical bending type continuous casting facility, since the cast piece is deformed from a straight shape to a curved shape by a cast piece supporting roller group located below the mold, in the casting mold, an outward curved surface of the cast piece is formed. The cast slab straightening reaction force (bending reaction force) acts on the inner surface of the mold. Slab correction area (slab support roller group)
The distance between the mold and the mold is short, the cross-sectional dimension of the slab is large, and
The smaller the radius of curvature, the greater the force that acts on the inner surface of the mold that is continuous with the outer curved surface of the slab. Therefore, in the continuous casting mold according to the present invention, which is applied to the vertical bending type continuous casting equipment, vertical grooves may be provided at two corners on the mold inner surface side that is continuous with the outer curved surface of the slab. There are cases.

As a special case, in the case of curved type continuous casting equipment for special steel, in order to prevent bulging of the slab due to static pressure of molten steel, the slab supporting rollers located below the mold are relatively dense. May be located in. At this time, the slab withdrawal force of the slab withdrawal device does not act as an external force on the mold in the cross-sectional direction, so that the slab (solidified shell) is uniformly pressed against the four inner surfaces of the mold. Therefore, in the case of such continuous casting equipment, it is preferable to provide vertical grooves at the four corners in the mold in the lower region of the mold.

Similarly, in the case of vertical bending continuous casting equipment for special steel, bulging of the slab due to static pressure of molten steel
In order to prevent this, the slab support roller group located below the mold may be arranged relatively densely. In addition, a sufficient vertical zone length may be provided to promote the levitation of inclusions in the molten steel. At this time, the straightening reaction force acting on the mold is extremely small, and the slab (solidified shell) is pressed against the four inner surfaces of the mold almost uniformly. Therefore, in the case of such continuous casting equipment, it is preferable to provide vertical grooves at the four corners in the mold in the lower region of the mold.

In the continuous casting mold according to the present invention, the position of the vertical groove in the casting direction is such that the vertical groove is formed from a position exceeding at least 50 mm below the molten steel level in the mold in the steady operation state to the mold outlet end. It is good to provide. The reason for this is that if the vertical groove is within the range of 50 mm or less from the molten steel level in the mold, the solidified shell near the corner has not grown sufficiently to withstand the molten steel static pressure, so cracking occurs at the top of the slab corner. This is because there is a risk of causing.

In the continuous casting mold according to the present invention, the width X of each vertical groove is set to 1/3 or less of the length L of one side of the mold inner surface at the mold outlet end. The reason will be described. When the width X of the flute exceeds 1/3 of the length L, most of the solidified shell flat surface portion (cast piece flat surface portion) remains separated from the inner surface of the mold, promoting sound solidification of the solidified shell flat surface portion. Instead, it will trigger a breakout. On the other hand, the peak contact pressure between the slab and the mold in the vicinity of the corner exists within 1/3 of the length L from the corner, and the solidified shell flat portion exceeding 1/3 of the length L from the corner is relatively large. It will be small.

[0026]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, a continuous casting mold (tube mold) described in each embodiment below.
Is made of copper or a copper alloy and is used for manufacturing square billets.

FIG. 1 is a vertical cross-sectional view (cross-sectional view in the casting direction) of the continuous casting mold according to the first embodiment of the present invention.
FIG. 2 is a view showing a cross-sectional shape of the continuous casting mold shown in FIG. 1, in which (a) is an AA sectional view, (b) is a BB sectional view, and (c) is a CC sectional view. , (D) are DD sectional views.

The continuous casting mold (tube mold) 100 according to this embodiment is, as shown in FIGS. 1 and 2,
The inner surfaces 105 to 108 of the mold are tapered so as to gradually shrink toward the lower mold outlet end. Also, this mold 1
00 is downward from the molten steel molten metal level M in the steady operation state, and in the present embodiment, in the lower region of the mold extending from the position of length Y ′ = 350 mm to the mold outlet end, the four corner portions 10 are provided.
1 to 104, vertical grooves 109 to 1 for forming an air gap between the corner of the solidified shell and its vicinity.
12 is provided.

The cross-sectional shape of the vertical grooves 109 to 112 is
It has a concave shape in which two straight line portions are connected by an arc portion. In this embodiment, the dimensions of the flutes 109-112 are
The groove width X (dimension on one side of the inner surface of the mold): 25 mm, the groove length Y: 200 mm, the groove depth Z: 0.5 mm, and the radius of the corner arc: 4.5 mm. The length L of one side of the inner surface of the mold at the outlet end of the mold is 130 mm.

The continuous casting mold 10 thus constructed.
According to 0, the corner part 1 in the mold in the lower region of the mold
Since the vertical grooves 109 to 112 are provided in 01 to 104, the vertical grooves 109 to 112 can avoid contact between the corner portion of the solidified shell and its vicinity and the mold 100. As a result, a large contact pressure that causes slab cracking is not generated between the solidified shell and the mold 100 in the lower region of the mold, slab cracking can be prevented, and the life of the mold 100 can be extended. Further, when the slab rhombus deformation occurs, it can be prevented from being promoted.

FIG. 3 is a diagram schematically showing a state where rhombus deformation occurs in a cast piece in the continuous casting mold of the first embodiment, (a) is a transverse sectional view, and (b) is [Fig. 3] is a diagram for explaining contact pressure in a solidified shell portion having an acute angle in (a). In FIG. 3B, the length of the arrow indicates the magnitude of contact pressure. As shown in FIG. 3, even if the slab rhombus deformation occurs, the vertical grooves 109 to 112
Then, since it is possible to avoid contact between the solidified shell and the mold 100, it is possible to prevent further progress of the ingot rhombus deformation.

Although the groove width X and the groove depth Z of the vertical grooves 109 to 112 are set to constant values without changing in the mold 100 of the first embodiment, the present invention is not limited to this and the groove width is gradually changed along the casting direction. It may be changed. For example, groove width X
May be enlarged toward the mold outlet end. In addition, the groove length Y of the vertical grooves 109 to 112 may be shortened (for example, about 100 mm) when casting is performed at a high casting speed where the thickness of the solidified shell is relatively thin. As a result, in a region where the thickness of the solidified shell is relatively thin, the corner of the solidified shell and the corner of the inner surface of the mold are surely brought into close contact with each other, and in the lower region of the mold, a large contact pressure that causes slab cracking between the solidified shell and the mold. Can be eliminated.

FIG. 4 is a vertical cross-sectional view of another continuous casting mold according to the first embodiment of the present invention, and FIG. 5 is a D-D cross-sectional view showing the cross-sectional shape of the continuous casting mold shown in FIG. is there. Here, this continuous casting mold 100 'is the same as the continuous casting mold 100 shown in FIG. 1 and FIG. 2 except that it has an expansion portion for expanding the vertical groove in the width direction at the mold outlet end. It is a composition.

As shown in FIGS. 4 and 5, this continuous casting mold 100 'has an expanding portion 120 for expanding the vertical grooves 109 to 112 in the width direction at the mold outlet end. In this example, a groove portion is provided along the entire circumference of the inner surface of the mold so that the ends of the vertical grooves 109 to 112 communicate with each other in the expanded portion 120.

By providing such an extension section 120,
The fact that slab cracking can be prevented and the life of the mold can be extended will be described. As mentioned above,
In the case of a well-maintained fully vertical continuous casting facility, the slab (solidified shell) is pressed evenly against the four inner surfaces in the mold. However, since there is always some misalignment on the pass line of the continuous casting equipment, the contact pressure between the cast and the mold on the misaligned side increases. This contact pressure becomes particularly large at the mold outlet end due to the influence of deviation from the regular alignment of the slabs connected below the mold. Further, as described above, in the case of the curved continuous casting equipment,
The contact pressure generated between the solidified shell and the mold in the lower region of the mold is larger on the inner curved surface than on the outer curved surface. Therefore, along with this, the contact pressure between the cast piece at the mold outlet end and the mold becomes particularly large. Also, in the case of vertical bending type continuous casting equipment, the contact pressure between the slab and the mold on the side on which the slab straightening reaction force (bending reaction force) acts as described above increases, and with this, especially the mold outlet end The contact pressure at the part becomes large. The distribution of the contact pressure at the mold outlet end has a peak at the mold outlet end and is smaller than the corner portion, but it has been confirmed that the contact pressure also increases in the flat portion. Such a large contact pressure between the solidified shell (mold slab) and the mold at the mold outlet end stops wear of the mold outlet end, shortens the life of the mold, and restrains the slab at the mold outlet end. Therefore, there is a problem that a large force acts on the surface of the slab and cracks in the slab occur. On the other hand, by providing the expanded portion 120 forming an air gap along the entire circumference of the inner surface of the mold at the mold outlet end, it is possible to reduce the peak of contact pressure at the mold outlet end including the flat surface portion. Therefore, slab cracking can be prevented, and the life of the mold can be extended.

FIG. 6 is a vertical sectional view of a continuous casting mold according to a second embodiment of the present invention, and FIG. 7 is a view showing a cross sectional shape of the continuous casting mold shown in FIG. ) Is A
-A sectional view, (b) is a BB sectional view, (c) is a CC sectional view, and (d) is a DD sectional view.

Continuous casting mold 200 according to the second embodiment.
Is for vertical bending type continuous casting equipment, and as shown in FIGS. 6 and 7, the inner surfaces 205 to 208 of the mold are tapered so as to gradually decrease toward the lower mold outlet end. Further, the mold 200 has a length Y ′ = 500 m in the present embodiment, which is downward from the molten steel level M in the steady operation state.
In the lower region of the mold from the position m to the mold outlet end,
Longitudinal grooves 209, 210 for forming an air gap between the corners of the solidified shell and the vicinity thereof in the two corners 201, 204 on the side of the mold inner surface 208 that is continuous with the outward curved surface of the slab. Is provided. In addition, in FIG. 6, a cast piece (not shown) removed from the mold 200 moves vertically for a predetermined length and then bends in the right direction in the figure.

The cross-sectional shape of the vertical grooves 209 and 210 is
It has a concave shape in which two straight line portions are connected by an arc portion. In this embodiment, the dimensions of the flutes 209, 210 are
The groove width X (dimension on one side of the inner surface of the mold): 25 mm, the groove length Y: 100 mm, the groove depth Z: 0.5 mm, and the radius of the corner arc: 4.5 mm. The length L of one side of the inner surface of the mold at the outlet end of the mold is 130 mm.

According to the continuous casting mold 200 for the vertical bending type continuous casting equipment constructed as above, the two corner portions 201, 204 on the mold inner surface 208 side which are continuous with the outer curved surface of the slab are vertically provided. Since the grooves 209 and 210 are provided, the vertical grooves 209 and 210 in the lower region of the mold allow
On the side of the mold inner surface 208 that is continuous with the outward curved surface of the slab, the corner of the solidified shell and its vicinity and the mold 200
It is possible to avoid contact with. As a result, a large contact pressure that causes slab cracks is not generated between the solidified shell and the mold 200 in the lower region of the mold, slab cracks can be prevented, and the life of the mold 200 can be extended. Further, when the slab rhombus deformation occurs, it can be prevented from being promoted.

FIG. 8 is a vertical cross-sectional view (cross-sectional view in the slab drawing direction) of the continuous casting mold according to the third embodiment of the present invention, and FIG. 9 shows the cross-sectional shape of the continuous casting mold shown in FIG. It is a figure, (a) is an AA sectional view, (b) is a BB sectional view, (c) is a CC sectional view, (d) is a DD sectional view.

Continuous casting mold 300 according to the third embodiment
Is for curved type continuous casting equipment, and has a tapered inner surface 305 to 308 which is gradually reduced toward the lower mold outlet end (see FIG. 9). Of the mold inner surfaces 305 to 308, reference numeral 308 indicates an outer curved surface, and reference numeral 306 indicates an inner curved surface. Further, the mold 300 is located below the molten steel surface level M in the steady operation state in the present embodiment in the lower part of the mold extending from the position where the length Y ′ = 500 mm to the mold outlet end, and both end sides of the inner curved surface 306. Vertical corners 309 and 310 for forming an air gap between the corners of the solidified shell and its vicinity are provided in the corners 302 and 303.

The cross-sectional shape of the vertical grooves 309 and 310 is
It has a concave shape in which two straight line portions are connected by an arc portion. In this embodiment, the dimensions of the flutes 309, 310 are
The groove width X (dimension on one side of the inner surface of the mold): 25 mm, the groove length Y: 200 mm, the groove depth Z: 0.5 mm, and the radius of the corner arc: 4.5 mm. The length L of one side of the inner surface of the mold at the outlet end of the mold is 130 mm.

According to the curved-type continuous casting mold 300 thus constructed, the vertical grooves 309 and 310 are provided in the corner portions 302 and 303 on the inner curved surface 306 side in the mold in the lower region of the mold. Since it is a thing, this vertical groove 30
9, 310 makes it possible to avoid contact between the corner of the solidified shell and its vicinity on the side of the inner curved surface 306 of the mold 300 and the mold 300. This prevents a large contact pressure between the solidified shell and the mold 300 from causing a slab crack in the lower region of the mold, thus preventing the slab crack and at the same time, the mold 30
It is possible to achieve a long life of 0, and to prevent the slab rhombus from being promoted when it occurs.

FIG. 10 is a vertical cross-sectional view (cross-sectional view in the slab drawing direction) of the continuous casting mold according to the fourth embodiment of the present invention.
FIG. 11 is a view showing a cross-sectional shape of the continuous casting mold shown in FIG. 10, in which (a) is an AA cross-sectional view and (b) is B.
-B sectional drawing, (c) is CC sectional drawing, (d) is DD sectional drawing. Here, the curved continuous casting mold 400 according to the fourth embodiment has the same configuration as the continuous casting mold 300 according to the third embodiment except that the shape of the vertical groove is different.

That is, the continuous casting mold 400 is
For curved type continuous casting equipment, the inner surfaces 405 to 408 of the curved mold are tapered so as to gradually decrease toward the lower mold outlet end (see FIG. 11). Inner surface of mold 4
Of 05 to 408, reference numeral 408 indicates an outer side curved surface, and reference numeral 406 indicates an inner side curved surface. In addition, the mold 400 has the inner curved surface 4 in the lower region of the mold.
Longitudinal grooves 409 and 410 for forming an air gap between the corners of the solidified shell and its vicinity are provided in the corners 402 and 403 on both end sides of 06.

The cross-sectional shape of the vertical grooves 409 and 410 is
It has a concave shape in which an arc portion and a straight portion are connected.
In this embodiment, the dimensions of the vertical grooves 409 and 410 are as follows: groove width X: 25 mm, groove length Y: 200 mm, groove depth Z: 0.
5 mm, radius of corner arc: 4.5 mm. The length L of one side of the inner surface of the mold at the mold outlet end is 1
It is 30 mm.

According to the curved type continuous casting mold 400 thus constructed, the vertical grooves 409 and 410 are provided in the corner portions 402 and 403 on both ends of the inner curved surface 406 in the mold in the lower region of the mold. Since the vertical grooves 409 and 410 are used, the inner curved surface 40 of the mold 400 is
It is possible to avoid contact between the corner of the solidified shell and its vicinity on the side of 6 and the mold 400. As a result, in the lower region of the mold, a large contact pressure that causes a slab crack does not occur between the solidified shell and the mold 400, and a slab crack can be prevented and the mold 4 can be prevented.
It is possible to prolong the service life of No. 00 and to prevent its acceleration when the slab rhombus deformation occurs.

[0048]

As described above, according to the mold for continuous casting of steel according to the present invention, an air gap is formed between the corner part of the solidified shell and its vicinity in the corner part in the mold in the lower region of the mold. Since the vertical groove for forming is provided, a large contact pressure that causes a slab crack between the solidified shell and the mold is not generated in the lower region of the mold, and it is possible to prevent the slab crack and to prevent the slab from breaking. It is possible to prolong the service life, and when the rhombus deformation of the cast piece occurs, it is possible to prevent its promotion.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a continuous casting mold according to a first embodiment of the present invention.

FIG. 2 is a view showing a cross-sectional shape of the continuous casting mold shown in FIG. 1, in which (a) is an AA cross-sectional view and (b) is B-.
B sectional view, (c) is CC sectional view, (d) is DD sectional view.

3A and 3B are diagrams schematically showing a state in which a slab rhombus deformation occurs in the continuous casting mold of the first embodiment of the present invention, in which (a) is a cross-sectional view and (b) is. It is a figure for demonstrating the contact pressure in the solidified shell part which makes an acute-angled shape in (a).

FIG. 4 is a vertical sectional view of another continuous casting mold according to the first embodiment of the present invention.

FIG. 5 is a DD cross-sectional view showing the cross-sectional shape of the continuous casting mold shown in FIG.

FIG. 6 is a vertical sectional view of a continuous casting mold according to a second embodiment of the present invention.

FIG. 7 is a view showing a cross-sectional shape of the continuous casting mold shown in FIG. 6, in which (a) is an AA cross-sectional view and (b) is B-.
B sectional view, (c) is CC sectional view, (d) is DD sectional view.

FIG. 8 is a vertical sectional view of a continuous casting mold according to a third embodiment of the present invention.

9 is a view showing a cross-sectional shape of the continuous casting mold shown in FIG. 8, in which (a) is an AA cross-sectional view and (b) is B-.
B sectional view, (c) is CC sectional view, (d) is DD sectional view.

FIG. 10 is a vertical sectional view of a continuous casting mold according to a fourth embodiment of the present invention.

11 is a view showing a cross-sectional shape of the continuous casting mold shown in FIG. 10, in which (a) is an AA cross-sectional view, (b) is a BB cross-sectional view, and (c) is a C- C sectional view, (d) is DD
FIG.

FIG. 12 is a diagram schematically showing a state where rhombus deformation occurs in a slab in a conventional continuous casting mold, in which (a) is a cross-sectional view and (b) is (a). It is a figure for demonstrating the contact pressure in the solidification shell part which makes an acute angle.

FIG. 13 is a diagram schematically showing a state where rhombus deformation occurs in a slab in a continuous casting mold of Prior Art 2, in which (a) is a cross-sectional view and (b) is (a). FIG. 4B is a view for explaining contact pressure at a solidified shell portion having an acute angle in FIG.

[Explanation of symbols]

100, 100 '... Continuous casting molds 101-104 ...
Mold corner portion 105-108 ... Mold inner surface 109-
112 ... Vertical groove 120 ... Expansion part 200 ... Continuous casting mold 201-204 ... Mold corner part 205-208
... Mold inner surface 209 to 212 ... Vertical groove 300 ... Continuous casting mold 301 to 304 ... Mold corner portion 305, 3
07 ... Mold inner surface 306 ... Inner curved surface 308 ... Outer curved surface 309, 310 ... Vertical groove 400 ... Continuous casting molds 401-404 ... Mold corner portions 405, 407
... Mold inner surface 406 ... Inner curved surface 408 ... Outer curved surface 409, 410 ... Vertical groove

Claims (4)

[Claims] 1. A mold for continuous casting of steel, from a position exceeding at least 50 mm downward from a molten steel level in the mold to a mold outlet end, to a corner part in the mold,
A vertical groove for forming an air gap is formed between the corner of the solidified shell and its vicinity, and the width of the vertical groove is set to 1/3 or less of the length of one side of the inner surface of the mold at the outlet end of the mold. A mold for continuous casting of steel characterized by. 2. When the continuous casting mold is for a vertical bending type continuous casting facility, the vertical grooves are provided at two corners on the inner surface side of the mold that is continuous with the outward curved surface of the slab. The mold for continuous casting of steel according to claim 1. 3. When the continuous casting mold is for a curved type continuous casting equipment, the vertical grooves are provided at two corners on the inner curved surface side in the mold. Mold for continuous casting of the described steel. 4. An expansion part for expanding the vertical groove in the width direction is provided at the mold outlet end.
Or the mold for continuous casting of the steel according to 3.