JPH0645056B2 - Mold for continuous casting - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold for cooling and solidifying a molten metal supplied in order to continuously cast a metal such as steel, and particularly to a thin-walled and wide-width mold. The present invention relates to a mold for continuous casting, which is suitable for obtaining a slab of various shapes.

[Prior Art] A mold used for continuous casting is a device in which a cavity (hollow shaft portion) is formed by a water-cooled mold, and molten metal (molten metal) supplied thereto is cooled and solidified to form a cast piece. In order to cool the molten metal in the cavity, a cooling water jacket is provided on the outside of the mold, and the cooling water is configured to flow along the outer peripheral wall of the mold. Continuous casting
Molten metal once stored in a tundish (molten metal pan) is supplied to such a mold to form a slab with at least the outer periphery solidified, and the slab is continuously drawn by a drawing device provided downstream of the mold. It is done by pulling out. The continuous casting method is called vertical type (vertical type or curved type), horizontal type, etc. depending on the casting direction (axial direction of the mold).

The continuous casting method is already widely used in the steel industry because of its uniform quality and high product yield.
In recent years, attempts have been made to obtain thin and wide slabs (for example, having a thickness of 50 mm or less) by a continuous casting method. This is to avoid the rolling step by obtaining a slab having dimensions as close as possible to a final product such as a steel plate.

In order to obtain a slab having a predetermined cross section by continuous casting, a mold having a cavity corresponding to the shape and size of the slab cross section is used. Therefore, for example, when casting a slab with a thin and wide rectangular cross section, conventionally, a mold having flat inner wall surfaces corresponding to the long side surface and the short side surface is combined to form a rectangular cross section. A mold with an empty cavity is used. For example, the mold for thin-walled rectangular slab shown in “Iron and Steel” Vol.74 (1988) No. 1, p. 91 also follows the above. The thinner and wider the slab, the more integrated the block (tube)
Since it is difficult to form such a cavity in the mold, a combination mold is adopted as described above. Also, since the mold shrinks somewhat during cooling while being pulled out of the mold, in order to maintain contact between the slab and the inner wall surface of the mold, both the long side surface and the short side surface should be adjusted according to the contraction amount of the slab. It is usual that the downstream side of the mold has a taper so that the face-to-face distance (cavity size) becomes smaller.

Regarding the thin cast piece, it is said that a continuous casting method in which the mold is closely connected to the tap hole of the tundish and the molten metal in the tundish is directly supplied to the cavity in the mold is suitable. There is. With this type, the flow path of the molten metal from the tundish to the mold can be wide and short, so that stable molten metal supply can be achieved even if the thickness of the cast piece is considerably thin. On the other hand, as is the case with many vertical continuous casting processes, in the case where the tundish and the mold are separately arranged and molten metal is supplied from the tundish to the mold through a long nozzle, It is difficult to obtain a slab with a thickness of 50 mm or less because the nozzle must be inserted at an appropriate position and the molten metal flow path in the nozzle is narrow and long.

[Problems to be Solved by the Invention] When continuously casting thin-walled / wide-width slabs using the conventional mold described above, the slab surface (wide-width surface sandwiching the thin-walled portion) is evenly formed on the long side surface of the mold. Since they do not come into contact with each other, there is a problem that it is difficult to obtain a good quality slab. This is
a) The taper between the long sides of the mold (gradual decrease in cavity thickness) does not exactly match the contraction of the wall thickness of the slab, and
b) The wide surface of the slab tends to warp inward and separate from the mold from around the center. An analysis of these two causes-firstly, a) shows that the thin part originally has a small thickness (for example, 50
mm or less), and the shrinkage amount in the thickness direction due to the cooling of the slab is extremely small, so the taper of the mold is likely to deviate from an appropriate value due to its processing error. Another factor is that the shrinkage amount of the slab slightly changes depending on the drawing speed and the temperature of the molten metal supplied.

The phenomenon of b) occurs when the initial solidified shell of the slab formed near the upstream end of the mold moves downstream in the mold, for example, when the temperature gradient in the solidified shell changes. That is, if the temperature difference between the inside of the solidified shell (close to the center of the slab, high temperature) and the outside (near the surface of the slab, low temperature) is larger than when the solidified shell was initially formed, shrinkage between the inside and the outside Due to the difference in the amount, the surface of the solidified shell (cast slab) warps inward in a concave shape. Since the flat inner wall surface of the mold prevents outward warpage, the temperature change of the solidified shell generally tends to cause the inward deformation of the slab as described above.

Due to such a cause, the wide surface of the slab tends to be separated from the inner wall of the mold particularly in the vicinity of the center thereof, but in such a case, the slab is unevenly cooled and a slab with good internal properties cannot be obtained. Not in. Further, when the above-mentioned warpage of the solidified shell occurs relatively early (upstream of the mold), the molten metal may intrude between the surface and the inner wall of the mold to cause a double skin-like surface defect.

When the slab width is wide, the amount of shrinkage in the width direction is large, so that the slab moves in the width direction (closer to the center) as it slides on the inner wall (long side surface) of the mold. However, for example, if the taper between the long side faces of the mold is too strong and the slab is tightened, or if the long side face has scratches parallel to the casting direction and the slab surface is caught by this, the slab width direction Movement of the cast iron is hindered and tensile stress is generated in that direction, and as a result, vertical cracks (cracks in the casting direction) may occur on the surface of the slab.

Depending on the mold, in order to increase the cooling capacity and increase the productivity, following the downstream end thereof, an auxiliary mold part in which a plurality of molds are movably combined with each other and each mold is pressed against the slab surface, That is, there is also one having a portion called an adjustable mold or a self-tapered mold. However, even in such an auxiliary mold, since the inner wall of each mold is flat (the curvature does not change even if there is a curved surface portion), uniform contact cannot be expected with the slab whose surface is warped as described above, and , Defects such as double skin and vertical cracks that have occurred once are not repaired.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and when casting a thin and wide slab, the wide surface of the slab is kept in contact with the mold, and the shrinkage is accompanied by cooling. By reducing the amount of movement of the wide surface of the slab in the width direction relative to the inner wall of the mold, it is possible to eliminate defects such as uneven cooling, double skin, and vertical cracks, and obtain a good slab. It is intended to provide a mold for continuous casting.

[Means for Solving the Problem] In order to achieve the above object, the continuous casting mold of the present invention has a length along the cross-sectional shape of a slab to obtain a continuous slab with a thin and wide shape. In a continuous casting mold in which a plurality of water-cooled molds are fixedly combined so as to have a side surface and a short side surface, and the upstream end of the mold is closely connected to the tap hole of the tundish, the direction in which the slab swells A part of the long side surface is recessed, and the recessed surface is a) a curved surface or a plurality of curved and continuous flat surfaces, and b) the transverse length of the long side surface including the recessed surface is It is formed so that it gradually decreases from the upstream end portion to the downstream portion to the extent that it does not exceed the shrinkage amount of the slab width due to cooling, and c) does not exist in the downstream end or in the vicinity including the downstream end.

Further, as in claim 2, a plurality of water-cooled molds are combined so as to be movable relative to each other, and an auxiliary mold part (that is, a part corresponding to the above-mentioned adjustable mold) configured to press each mold against the surface of the slab, It may be provided coaxially after the downstream end.

[Operation] The continuous casting mold according to claim 1 of the present invention has its upstream end densely connected to the tap hole of the tundish, and thus is suitable for obtaining a thin cast piece as described above. ing.

And according to this mold, the transverse length of the long side surface of the mold including the above-mentioned recessed surface gradually decreases from the upstream end to the downstream of the mold to an extent not exceeding the shrinkage amount of the slab width due to cooling. Even though the width of the slab contracts while the slab is drawn out from the mold, the amount of movement of the slab surface in the width direction relative to the long side surface of the mold is small. Therefore,
As described above, even if the movement in this direction is obstructed, the tensile stress generated in the slab is small and vertical cracking does not occur.

In addition, the recessed surface causes the cavity to bulge outward, and the degree of bulging becomes smaller toward the downstream side of the mold.Therefore, the action of pushing the wide surface of the cast slab out from the outside to the inside Have. In other words, as mentioned above, even if the wide surface of the slab (solidified shell) is slightly separated from the inner wall of the mold due to the temperature change of the solidified shell, when the slab is pulled out and moved downstream, the two immediately recover contact. Come to do. When the mold and the surface of the slab are kept in contact, the slab is cooled uniformly, so that the internal quality is good, and it is possible to increase the drawing speed to improve the productivity.
Since the recessed surface disappears at or near the downstream end of the mold, the cast piece that has been pulled out of the mold has no bulging portion, and is not warped even in a concave shape. The surface will be formed.

According to the mold in which the auxiliary mold portion is subsequently provided as in claim 2, the drawing speed can be increased and the productivity can be maximized. This is because the surface of the slab that enters the auxiliary mold part after passing the vanishing point of the recessed surface is flat as described above, so that the mold of the auxiliary mold part is entirely in contact with the slab and the cooling capacity is uniform. And because it maximizes. Since the uniform cooling is performed, the internal quality of the slab is, of course, good.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show, as a first embodiment, a horizontal continuous casting mold for obtaining a steel slab having a thin and wide cross section. Fig. 1 is a vertical cross-sectional view of the mold and main casting equipment near the center line, and Fig. 2 (a), (b), (c)
Are cross-sectional views taken along lines (a)-(a), (b)-(b), and (c)-(c) of FIG. 1, respectively (however, only the main parts are shown in FIGS. 1 (a) and (c)). ).

As the main equipment for horizontal continuous casting shown here, as shown in FIG. 1, a mold A is connected to a tundish E for storing molten steel M, and a drawing roll G is arranged downstream thereof. The mold A has a cavity Aa formed therein by a water-cooled copper alloy mold 1, and its upstream end is connected to a nozzle Ea, which is a tap hole of the tundish E, via a refractory Eb (commonly called a break ring). The molten steel M supplied to the tundish E directly flows into the cavity Aa and is cooled there to become a cast slab C because they are closely connected. Since the slab C is continuously pulled out by the roll G,
The molten steel M constantly flows into the cavity Aa and is continuously cast. Ca refers to a solidified shell on the surface of the cast slab C, and is a portion where the molten steel M contacts the inner wall of the assembling mold 1 and is cooled and solidified. The cross-sectional dimension of the cast slab C is set by selecting the combination of the assembling mold 1 and the refractory Eb. In this embodiment, the final dimension (after cooling) is set to 30 mm × 300 mm width. ing.

Steel has a high melting point, and therefore the temperatures of the molten steel M and the solidified shell Ca are also high.
In order to prevent sticking and to continuously generate solidified shell Ca, the slab C is vibrated several tens to several hundreds of times per minute by the drawing roll G. That is, the roll G repeatedly pulls out the slab C in the direction of the arrow in the figure while repeating normal rotation, stopping, and slight reverse rotation.

Mold A of this embodiment is, as shown in each of FIG. 2, molds 1a and 1b having long side surfaces corresponding to the wide surfaces of the slab C as inner walls, and molds 1c and 1d having short side surfaces. And molds are fastened to each other in a fixed state to form a combined mold 1, and cooling water jackets 2a, 2b, 2c, 2d are provided on the outside of each mold 1a, 1b, 1c, 1d, and cooling water is circulated between them. Is. Partition plates 2'a, 2'b are provided inside the long side jackets 2a, 2b to rectify the cooling water and enhance the cooling efficiency.

The feature of the mold A is that the inner walls of the molds 1a and 1b, that is, a part of the long side surfaces are recessed toward the outside of the cavity Aa. The recessed surface p is a curved surface which is always an arc in a cross section as shown in FIGS. 2 (a) and 2 (b), and its height (depth) and width become smaller toward the downstream of the mold A. That is, the curved surface is equal to a part of the side surface of a certain cone. The degree of recession of the recessed surface p becomes smaller toward the downstream of the mold A, and disappears at the downstream end as shown in FIG. 2 (c). The cross-sectional length of the long sides of the molds 1a and 1b including the recessed surface p, that is, the arc length Ua- in FIG. 1 (a).
Va, the length Ub-Vb of the Ω-shaped side in FIG. 3B, and the straight length Uc-Vc in FIG. 3C are cooled from the upstream end of the mold A (end face k described later) to the downstream. The slab C was set to be gradually shortened in accordance with the dimensional change of the cast slab C which contracts. In other words, from the slab C side, the solidified shell Ca contracts while moving in the mold A, but when it is pulled out at a predetermined speed, the amount by which the wide surface contracts in the width direction from the upstream end to the downstream. Is equal to the reduction amount of the above-mentioned transverse length of the molds 1a and 1b. Since the distance between the inner walls (short side faces) of the molds 1c and 1d was constant, instead of the taper (reduction of cavity width) that was conventionally provided between the short side faces, the crossing of the long side faces was performed as described above. The length has been reduced. In addition, mold 1
The short sides of c and 1d are flat, and their transverse length is constant.

As described above, the connection refractory Eb is interposed at the upstream end of the mold A, but as shown in FIGS. 1 and 2 (a), the refractory Eb is formed only by a flat surface. At the same time, a flat surface j having a step and a recessed surface p was provided at the upstream ends of the molds 1a and 1b, and the refractory material Eb was inserted between the flat surfaces j. This is done in order to avoid an increase in processing cost due to forming a curved surface corresponding to the recessed surface p on the refractory Eb which is a consumable item. A concave end surface k is provided between the recessed surface p and the flat surface j so that the tip end surface of the refractory Eb to be inserted is continuous with the end surface k. In addition, six circular molten steel passage holes are formed near the center of the refractory Eb.

According to the mold A of this embodiment, a thin and wide cast piece C is cast as follows.

When the molten steel M is supplied from the tundish E into the cavity Aa of the mold A through the relatively large cross-sectional passage holes of the nozzle Ea and the connecting refractory Eb, the tip surface of the connecting refractory Eb or the mold 1a, A solidified shell Ca is formed from the position of the end face k of 1b, and the solidified shell Ca grows as a cast slab C and continues, whereby the continuous casting is performed as described above. Since the solidified shell Ca is formed along the shape of the cavity Aa, for example, at the positions (b)-(b) in FIG. 1, there is a bulge in the center of the wide surface as shown in FIG. 2 (b). It has a cross-sectional shape. Since the slab C moves in the mold A while being vibrated by the drawing roll G, the slab C is smoothly cast without breaking the solidified shell Ca or sticking to the inner wall of the mold.

The slab C (solidified shell Ca) contracts considerably in the width direction as it is cooled due to its wide width, but the transverse lengths of the long sides of the molds 1a and 1b are the upstream end due to the concave surface p. Since the amount of shrinkage gradually decreases from the part to the downstream, the surface of the cast slab C is drawn when the cast slab C is pulled out at a predetermined speed.
It does not move in the width direction with respect to the inner walls of a and 1b. Therefore, tensile stress does not occur in the width direction near the surface of the cast slab C, and vertical cracking does not occur.

In addition, since the degree of recession of the recessed surface p decreases toward the downstream of the mold A, the wide surface of the solidified shell Ca is pulled inward by the molds 1a and 1b while moving to the downstream side in the mold A. As it is driven in, it constantly contacts its inner wall. Thus, the solidified shell Ca is uniformly cooled while maintaining contact with the inner walls of the molds 1a and 1b, and the bulging portion is corrected to the downstream end of the mold A where the concave surface p disappears,
The mold A exits as a cast slab C having a flat wide surface.
These points are as described in the section “Action”.

Since the surface of the cast slab C that exits the mold A is a flat surface without a bulge, a special structure different from the conventional one is not necessary for the drawing roll G and other transport rolls (not shown). .

By the way, the mold 1c, 1d (short side surface) is not provided with a recessed surface,
Although the length of the short side is not changed, the cooling delay, deformation (warpage) or vertical cracking does not occur on both side surfaces (short side surface) of the cast slab C. Near this surface is mold 1
This is because, because it is surrounded by the side portions of c and 1d and the molds 1a and 1b, the solidified shell Ca is rapidly generated due to strong cooling, and the span is small, so that the shrinkage amount is small and it is difficult to deform.

As described above, in the mold A, the cross-sectional length of the long side surface of the cavity Aa is changed in accordance with the natural contraction of the width of the slab C (solidified shell Ca). Does not necessarily correspond to the change in the cross-sectional area of the slab C. Rather, the cross-sectional area of the cavity Aa is reduced at a higher rate than the change due to the natural contraction of the slab C, but even if the solidified shell Ca is pressed inward by this, the molten steel M inside it
Since it is only pushed back to the upstream side, there is no inconvenience that the solidified shell Ca cannot be withdrawn.

In the above embodiment, the end face k provided at the upstream end of the molds 1a and 1b
If a similar end surface is formed at the same position on the molds 1c and 1d as the solidified shell Ca starts to be generated from here, for example, the tip surface of the nozzle Ea is moved forward from the state shown in FIG. If it is projected and brought into close contact with the assembled mold 1, the connecting refractory Eb need not be used. Further, if each inner wall surface of the assembled mold 1 is coated with an appropriate coating having heat resistance and lubricity, it is not necessary to withdraw the slab C while vibrating it as described above.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a view showing a mold for horizontal continuous casting of steel for obtaining a slab having a thin and wide rectangular cross section. As in FIG. 1, a slab D is placed in the right direction of the drawing.
Is cast. 4 (a), (b), (c) and (d) are respectively (a)-(a), (b)-(b), (c)-(c) and (of FIG. It is a transverse cross-sectional view (d)-(d) (only the main part is shown except for the figure (d)).

The mold B shown in FIG. 3 is composed of a mold B1 in which a cavity Ba is formed by the assembled mold 11 which has been fastened, and an auxiliary mold B2 combined so as to be relatively movable so as to be pressed against the surface of the cast slab D. The mold B1 is similar to the mold A in the above-mentioned embodiment, and has molds 11a and 11b having long sides.
And the molds 11c and 11d having short side surfaces are fastened to each other to assemble the mold 11
And equipped with a cooling water jacket 12 and a partition plate 12 'on the outside, respectively, and connect the upstream end of the connection refractory
It is connected to the nozzle Fa of the tundish F via Fb.

The auxiliary mold B2 is a so-called adjustable mold in which the molds 21a and 21b move relative to each other, and is arranged in the outer frame 24 as shown in FIG. 4 (d).
Of the two molds 21a and 21b, the upper mold 2 having a U-shaped cross section
1a is pressed against the slab D by the urging force of the spring 25. The slab D is the lower mold 21b due to the action of its own weight and this urging force.
Also makes strong contact with. Cooling water jackets 23a and 23b and partition plates 23'a and 23'b are also provided outside the molds 21a and 21b, and the graphite liner 2 is provided inside the molds 21a and 21b.
2a and 22b are installed respectively. Graphite liner 22a, 22b
Has a high thermal conductivity and a self-lubricating property, so that the withdrawal resistance of the cast slab D in the auxiliary mold B2 is small. In the portion of the auxiliary mold B2, even if the slab D contracts and its thickness decreases, the molds 21a, 21b (liner 22
Since the long side surfaces of a and 22b) are always in contact with each other, cooling of the cast slab D proceeds uniformly and surely.

Also for this mold B, the molds 11a and 11b of the mold B1
A concave surface q is formed on the inner wall, that is, the long side surface, so that the cavity Ba bulges outward. Unlike the mold A of the above-mentioned embodiment, the recessed surface q has a concave surface as shown in FIGS.
It consists of two continuous planes that bend and appear as shown in the figure.
It becomes smaller as it goes downstream, and disappears near the downstream end of the mold B1 as shown in FIG. 4 (c). And the transverse length of the long side surface of the molds 11a, 11b including the recessed surface q, that is, FIG.
(a), the bending line lengths Xa-Ya and Xb-Yb in (b), and the linear length Xc-Yc in the same figure (c) are from the upstream end to the downstream of the mold B1 in the same manner as in the above example. The temperature was set so as to be gradually shortened substantially in accordance with the dimensional change of the cast slab D which contracts when cooled. The short sides of the molds 11c and 11d are flat, and their transverse lengths are constant.

Then, the connection refractory Fb has the concave surfaces q of the molds 11a and 11b and the mold 1
An outer shape was formed along the flat short side surfaces of 1c and 11d, seven molten steel passage holes were opened, and then they were fitted into the upstream end of the mold B1. Since the recessed surface q is a flat surface, it is easy to form the surface along the recessed surface q on the refractory material Fb. A thermocouple 13 is inserted from the outside in the vicinity of the mold 11b where the refractory Fb is fitted.

Also in the mold B of this embodiment, the wide surface of the slab D is kept in contact with the molds 11a and 11b as in the case of the first embodiment, and the wide surface of the slab D is contracted by cooling. Since a small amount moves in the width direction with respect to the long side surfaces of the molds 11a and 11b, it is possible to obtain a good quality slab without deformation, uneven cooling, and vertical cracking.

Moreover, in this mold B, since the auxiliary mold B2 is provided after the mold B1, there is an advantage that the cooling ability for the cast slab D is particularly high. This is because the graphite liners 22a and 22b of the molds 21a and 21b to be pressed are in contact with the slab D having the flattened long side surface from the downstream end of the mold B1 in a wide area over almost the entire long side surface. This is because the slab D is effectively cooled. Since this contact is uniform, the entire slab D is uniformly cooled, and therefore its internal quality is also good. If such a high cooling capacity of the mold B is utilized, it is possible to increase the drawing speed and improve the productivity.

Further, the thermocouple 13 inserted into the mold 11b can detect the generation state of the solidified shell near the upstream end of the connected refractory material Fb or the mold B1. For example, if the solidified shell is not properly pulled out by breaking or sticking in the mold B1, the thermocouple 13 will cause the mold 11 to
Notify that the temperature of b has dropped. By receiving such information from the thermocouple 13 and changing the drawing speed and the vibration pattern applied to the cast slab D, continuous casting can be performed more smoothly.

The mold 21a (graphite liner 22 in the auxiliary mold B2)
The short side surface of a) does not make positive contact with the slab D. Therefore, the auxiliary mold B2
It may be composed of two plate-shaped molds having only long sides.
In this way, the short side surface of the slab D does not face the mold after exiting the mold B1, but since the slab D is thin-walled, the short side surface is cooled through the long side surface, which causes a problem. Does not happen.

Further, in the above embodiment, the recessed surface q disappears near the downstream end of the mold B1, but by increasing the spring constant of the spring 25, for example, the molds 21a, 21b of the auxiliary mold B2.
If it is difficult for the cast piece D to recede outward with respect to the slab D, the recessed surface q is formed in the auxiliary mold B2, that is, the molds 21a and 21b (graphite liner 22).
It can also be formed by extending to the middle of a, 22b).

Although the present invention has been described above with reference to the two embodiments, the present invention can be carried out as follows.

a) The recessed surface is recessed from both ends of the long side surface of the mold, its cross section is always an arc, and the transverse radius gradually decreases as the radius of curvature gradually increases from the upstream end of the mold to the downstream. It is formed as a curved surface. Alternatively, the recessed surface is formed by various curved surfaces or flat surfaces other than those described in the embodiments, such as bending to form three or more continuous flat surfaces.

b) The concave surface is formed on only one of the two facing long side surfaces.

c) From the upstream end of the mold to the downstream, the transverse length of the long side surface including the recessed surface is reduced at a rate smaller than the shrinkage amount of the slab width due to cooling, and the remainder (shrinkage amount of the slab width- The decrease amount of the long side crossing length) is set as the taper between the short side faces (gradual decrease of the cavity width).

d) The present invention is applied not only to a slab having a rectangular cross section, but also to a slab of another shape having a thin-walled / wide portion, for example, a mold for casting a beam blank as a shaped steel material.

e) Cast non-ferrous metal slabs such as copper and aluminum as well as steel.

f) The mold is erected vertically or diagonally, and is tightly connected to the tap hole at the bottom of the tundish, and cast by the vertical continuous casting method.

g) There is a casting method in which the slab is pulled out at a constant speed without vibrating and the mold is vibrated in the casting direction together with the tundish, but it goes without saying that the present invention can also be applied to such a method. Also in this respect, it does not matter whether the continuous casting method is a horizontal type or a vertical type.

[Effects of the Invention] According to the continuous casting mold of the present invention described above,
As described below, a good quality continuous slab having a thin and wide shape can be obtained.

1) Since the long side surface of the mold surely contacts the wide surface of the slab, uneven cooling or double skin defect does not occur in the slab.

2) The amount of movement of the wide surface of the slab in the width direction with respect to the inner wall of the mold due to shrinkage due to cooling is small, so vertical cracks do not occur on the wide surface. This means that even if the taper between the long side surfaces of the mold deviates somewhat from the proper value (or even if there is no taper), or the long side surface may have scratches in the casting direction, the mold Manufacturing costs are reduced and the mold can be used for extended periods of time.

3) According to the continuous casting mold of claim 2, since the cooling capacity of the auxiliary mold is uniformly and maximally exerted on the cast piece, the cast piece having good internal quality can be efficiently cast. it can.

[Brief description of drawings]

The drawings all show a mold for horizontal continuous casting of steel, and FIG. 1 is a longitudinal sectional view of a mold and main casting equipment according to the first embodiment, and FIGS. 2 (a), (b), ( 3C is a cross-sectional view taken along lines (a)-(a), (b)-(b), and (c)-(c) of FIG. 1, respectively. Further, FIG. 3 is a longitudinal sectional view of the mold according to the second embodiment, and FIGS. 4 (a), (b), (c) and (d) are respectively (a)-(a) of FIG. It is a transverse cross section in (b)-(b), (c)-(c), (d)-(d). A, B, B1 ... Mold, B2 ... Auxiliary mold, Aa, Ba ... Cavity, C, D ... Slab, E, F ... Tundish, E
b, Eb ... connected refractory, G ... drawing roll, M ... molten steel, p,
q ... recessed surface, 1,11 ... assembly mold, 1a, 1b, 1c, 1d, 11a, 11b, 11c, 11d, 21a,
21b… Mold, 2,12,23… Cooling water jacket.

Claims (2)

[Claims] 1. To obtain a continuous cast slab having a thin and wide shape,
Composed of a plurality of water-cooled molds in a fixed state so as to have a long side surface and a short side surface along the cross-sectional shape of the slab,
In a continuous casting mold in which its upstream end is tightly connected to a tap hole of a tundish, a part of the long side surface is recessed in a direction in which the cast swells,
The recessed surface is a) curved surface or a plurality of curved and continuous flat surfaces, and b) the transverse length of the long side surface including the recessed surface is the width of the cast slab obtained by cooling from the upstream end to the downstream. C) The continuous casting mold formed so that the shrinkage amount does not exceed the shrinkage amount and does not exist in the downstream end or in the vicinity including the downstream end. 2. A method according to claim 1, wherein a plurality of water-cooled molds are combined so as to be movable relative to each other, and an auxiliary mold portion configured to press each mold against the surface of the slab is provided subsequent to the downstream end. Mold for continuous casting.