JP7160026B2 - Dummy bar for continuous casting machine, continuous steel casting method, steel slab manufacturing method, and steel product manufacturing method. - Google Patents

Description

The present invention relates to a dummy bar for a continuous casting machine, a continuous steel casting method, a steel slab manufacturing method, and a steel product manufacturing method.

In continuous casting of steel, continuous casting is started with a dummy bar inserted in the machine including the mold of the continuous casting machine. At this time, a dummy bar head provided at the tip of the dummy bar is inserted into the mold. Further, in the continuous casting machine, by exchanging or deforming the mold to change the shape of the mold (cross-sectional shape perpendicular to the casting direction), it is possible to produce slabs with different cross-sectional shapes.
However, in a continuous casting machine that performs casting with a plurality of mold shapes, if the dummy bar head does not match the mold shape, the conventional method is to replace the dummy bar head with one that matches the mold shape. . In addition, as a method of using the same dummy bar head regardless of the shape of the mold, there is a method of using a special mold in which the short sides of the mold are movable so that the mold dimensions are always the same at the start of casting (see Patent Document 1). , there is a method of making a part of the dummy bar head movable and deforming it along the mold (see Patent Document 2).

JP-A-7-100601 Japanese Utility Model Laid-Open No. 6-5745

By the way, as described above, when replacing the dummy bar head of the dummy bar according to the mold shape in continuous steel casting, it is necessary to prepare a plurality of dummy bar heads according to the mold shape, which is economical and management. It was a heavy burden.
Moreover, the method of Patent Document 1 uses the same dummy bar head regardless of the shape of the mold, but requires modification of the mold itself. Furthermore, when the difference in mold shape is small, such as the presence or absence of chamfering at the corners of the mold, there is little advantage.
Furthermore, the method of Patent Document 2 uses the same dummy bar head regardless of the shape of the mold as in Patent Document 1, but requires modification of the dummy bar head. Furthermore, since the movable mechanism is complicated, it has been difficult to fabricate a dedicated dummy bar when the dimensional difference in the shape of the mold is small, such as whether the mold corners are chamfered or not.

Therefore, the present invention has been made by paying attention to the above problems, and is a continuous casting method that uses at least two types of molds with different mold corner shapes depending on the presence or absence of chamfering. It is an object of the present invention to provide a dummy bar for a continuous casting machine, a steel continuous casting method, a steel slab manufacturing method, and a steel product manufacturing method that can change the shape of the dummy bar head.

According to one aspect of the present invention, there is provided a first mold in which the mold corners are chamfered, and the mold corners are not chamfered or the mold corners are chamfered by a smaller chamfering amount than the first mold. In a continuous casting machine for steel in which at least two types of molds of the second mold are used by exchanging, a dummy bar of the continuous casting machine used at the start of continuous casting, wherein at the start of the continuous casting, the continuous casting machine The dummy bar head has a corner portion, which is a portion corresponding to the mold corner portion, chamfered according to the shape of the mold corner portion of the first mold. A dummy bar for a continuous casting machine is provided, which has an attachment for reducing the amount of chamfering of the corner and is configured to be attachable to the corner.

According to one aspect of the present invention, there is provided a first mold in which the mold corners are chamfered, and the mold corners are not chamfered or the mold corners are chamfered by a smaller chamfering amount than the first mold. A continuous casting method for steel using at least two different molds of the second mold, wherein at the start of continuous casting, the dummy bar of the continuous casting machine according to claim 1 or 2 is used, and the second mold is used. When performing the continuous casting with the first mold, the dummy bar with the attachment removed is used, and when performing the continuous casting with the second mold, the dummy bar with the attachment attached is used. , a method for continuous casting of steel is provided.
According to one aspect of the present invention, there is provided a steel slab production method for producing a steel slab by the steel continuous casting method according to one aspect described above.
According to one aspect of the present invention, there is provided a method for producing a steel product by subjecting a slab cast by the method for producing a steel slab according to one aspect described above to a post-treatment to obtain a steel product.

According to one aspect of the present invention, it is possible to change the shape of the dummy bar head easily and inexpensively in a continuous casting method in which at least two types of molds having different mold corner shapes depending on the presence or absence of chamfering, etc. are used by exchanging. , a continuous casting machine dummy bar, a steel continuous casting method, a steel slab manufacturing method and a steel product manufacturing method are provided.

It is a schematic diagram showing a continuous casting machine in one embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the dummy bar head which concerns on one Embodiment of this invention, (A) shows a side view, (B) shows a top view. It is a front view showing a dummy bar head according to one embodiment of the present invention. 4 is an enlarged view of a portion surrounded by a dotted line in FIG. 3; FIG. It is a schematic diagram which shows an attachment, (A) shows a front view, (B) shows a top view. FIG. 4 is a schematic diagram showing a method of attaching an attachment to a dummy bar head, where (A) is a perspective view showing the dummy bar head with the attachment removed, and (B) shows the dummy bar head with the attachment attached. It is a perspective view. FIG. 4 is a schematic diagram showing a state in which a dummy bar head from which an attachment has been removed is inserted into the first mold; FIG. 10 is a schematic diagram showing a state in which a dummy bar head to which an attachment is attached is inserted into a second mold;

The following detailed description describes embodiments of the invention with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals, and overlapping descriptions are omitted. Each drawing is schematic and may differ from the actual one. In addition, the embodiments shown below are examples of apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is based on the material, structure, arrangement, etc. of component parts. It is not specific to the following. Various modifications can be made to the technical idea of the present invention within the technical scope defined by the claims.

<Dummy bar for continuous casting machine>
A dummy bar 4 according to one embodiment of the present invention is used in a continuous casting machine 1 for continuously casting steel, as shown in FIG. Although the continuous casting machine 1 is not particularly limited, in this embodiment, as an example, a billet or a bloom having a rectangular cross-sectional shape perpendicular to the casting direction and having a nearly square cross-sectional shape is cast. A continuous casting machine 1 includes a mold 2 into which molten steel is poured, a plurality of rolls 3 including pinch rolls, and dummy bars 4 . A plurality of rolls 3 form a roll group in which the cast piece to be cast is sandwiched between the long sides, and a plurality of the roll groups are provided side by side in the casting direction.

Further, in the present embodiment, the continuous casting machine 1 uses two types of molds 2, a first mold 2A and a second mold 2B, which have different cross-sectional shapes perpendicular to the casting direction. As shown in FIG. 7, the first mold 2A has a rectangular shape when viewed from the casting direction, and the casting spaces of the four mold corner portions 21A (21), which are the corners of the rectangular shape, are chamfered. have a shape. In this embodiment, as an example, the mold corner portion 21 is chamfered (C-chamfered) at 45° in the casting space. In the first mold 2A in which mold corners 21 are chamfered (tapered), the cooling of the corners of the slab is promoted, and the occurrence of casting defects can be suppressed. As shown in FIG. 8, the second mold 2B has a rectangular shape when viewed from the casting direction, and has a shape in which four mold corner portions 21B (21) are not chamfered. The first mold 2A and the second mold 2B have a maximum length in the long side direction (horizontal direction in FIGS. 7 and 8) and a maximum length in the short side direction (vertical direction in FIGS. 7 and 8). are the same length. That is, the first mold 2A and the second mold 2B differ only in the shape of the mold corner portions 21A and 21B.

As shown in FIG. 1, the dummy bar 4 is inserted into the continuous casting machine 1 before the start of continuous casting, and has a dummy bar head 5 at its tip that is inserted into the mold 2 .
The dummy bar head 5 has a rectangular shape when viewed in a direction parallel to the insertion direction of the dummy bar 4, as shown in FIG. In this embodiment, the dummy bar 4 is inserted into the continuous casting machine 1 from below as shown in FIG. That is, the up-down direction in FIG. 2 and the front-back direction in FIG. 3 are parallel to the insertion direction of the dummy bar 4 . The dummy bar 4 is not limited to the above example, and may be inserted into the continuous casting machine 1 from above (that is, from the mold 2 side).

The dummy bar head 5 serves as the bottom of the mold 2, which is inserted into the mold 2 and receives molten steel at the start of continuous casting. Therefore, in the dummy bar head 5, the maximum length of the long side of the rectangular shape is shorter than the maximum length of the long side of the casting space of the mold 2, and the maximum length of the short side of the rectangle is the same as the casting space of the mold 2. shorter than the maximum length of the short side of If the dimensions of the dummy bar head 5 (maximum length of the long side and short side) are too small, the clearance from the mold 2 becomes large, resulting in a problem of deterioration in sealing performance. For this reason, the dimensions of the dummy bar head 5 are set to a size that provides an appropriate clearance from the mold 2 so that the sealing performance is not a problem. Moreover, the dummy bar head 5 has a connecting portion 52, which is a depression that connects with the cast slab, on the tip side (upper end side in FIG. 1).

Furthermore, the dummy bar head 5 has rectangular corners, and four corners 51 corresponding to the mold corners 21 of the mold 2 are chamfered according to the mold corners 21A of the first mold 2A. shape. In this embodiment, as an example, the corner portion 51 is chamfered at 45° (C-chamfering) in the same manner as the mold corner portion 21A. In addition, the amount of chamfering of the corner portion 51 is set to such an extent that the dummy bar head 5 can be inserted into the first mold 2A. It is desirable to set the clearance with 2A to be approximately the same as the long side and the short side. Furthermore, as shown in FIG. 6(A), a plurality of connection holes 511 whose inner periphery is threaded are formed in the corner portion 51 so as to line up in the direction of insertion into the mold 2 .

Further, the four corner portions 51 are configured so that attachments 6 for reducing the amount of chamfering of the corner portions 51 can be attached. The attachment 6 has a prismatic shape, as shown in FIG. In this embodiment, the attachment 6 has a trapezoidal shape when viewed from a direction parallel to the direction of insertion into the mold 2, as shown in FIG. 5(A). That is, as shown in FIG. 8, the attachment 6 is attached to the corner portion 51, and in a state in which the dummy bar head 5 is inserted into the second mold 2B, the corner portion 51 and the second mold 2B are separated from each other when viewed from the casting direction. It has a shape that fills the gap with 2B. In the present embodiment, the attachment 6 has a trapezoidal shape, that is, a shape in which corners adjacent to the triangular mold corner portions 21B are chamfered (C-chamfered) when viewed from the insertion direction of the dummy bar head 5. Other shapes may be used as long as the chamfering amount of 51 is reduced. For example, the shape of the attachment 6 may be an unchamfered triangular shape, or a shape in which the C-chamfered corners in the present embodiment are R-chamfered.

Further, the attachment 6 is formed to a dimension that provides a clearance from the second mold 2B to the extent that the sealing performance is not a problem when attached to the corner portion 51, as shown in FIG. As shown in FIG. 4, the attachment 6 is suspended from the dummy bar head 5 so that the surface of the long side of the dummy bar head 5 is located inside the dummy bar head 5 and is positioned on the long side. It is preferable to have a shape that forms a step. The long-side surface of the dummy bar head 5 is the surface facing the roll 3 when the dummy bar 4 is inserted into the continuous casting machine 1 . When inserting the dummy bar 4 into the continuous casting machine 1 , the dummy bar head 5 moves in the machine while the long sides are in contact with the rolls 3 . At this time, since the pressing force of the roll 3 is applied to the dummy bar head 5, the deformation and damage of the attachment 6 can be prevented by forming the stepped shape of the attachment 6 as shown in FIG.

Furthermore, it is preferable that the tip side surface of the attachment 6 is approximately the same height as the tip side surface of the corner portion 51 of the dummy bar head 5 when attached to the dummy bar head 5 . The length of the attachment 6 in the insertion direction is not particularly limited, and may be shorter than the length of the corner portion 51 of the dummy bar head 5 in the insertion direction.
Further, the material of the attachment 6 is not particularly limited, but like the dummy bar head 5, one having excellent heat resistance and strength is preferable, and from the viewpoint of cost, it may be made of steel.

Furthermore, the attachment 6 has a plurality of mounting holes 61 arranged in the insertion direction as a mounting mechanism to the dummy bar head 5, as shown in FIG. 5(B). The mounting hole 61 is provided at a position corresponding to the connection hole 511 of the corner portion 51 . When attaching the attachment 6 to the dummy bar head 5, as shown in FIG. 6, the bolt 7 is screwed into the connection hole 511 of the corner portion 51 through the attachment hole 61 of the attachment 6, so that the attachment 6 is attached to the dummy bar head. Fixed to 5. Although the number of connecting holes 511 and mounting holes 61 provided in the insertion direction is not particularly limited, it is preferable that the number is plural in consideration of the installation accuracy of the attachment 6 .

<Steel continuous casting method>
Next, the continuous casting method for steel according to the present embodiment will be described. In this embodiment, whether or not the attachment 6 is attached to the dummy bar head 5 is determined according to the type of mold 2 to be used. Specifically, when continuous casting is performed using the first mold 2A in which the mold corners 21A are chamfered, the dummy bar 4 in a state in which the attachment 6 is not attached to the dummy bar head 5 (a state in which the attachment 6 is removed). Use When continuous casting is performed using the second mold 2B in which the mold corners 21B are not chamfered, the dummy bar 4 with the attachment 6 attached to the dummy bar head 5 is used.

In this embodiment, the dummy bar 4 is inserted into the continuous casting machine 1 and the dummy bar head 5 is inserted into the mold 2 before starting continuous casting. At this time, as shown in FIGS. 7 and 8, the shape of the corner portion 51 of the dummy bar head 5 is adjusted in accordance with the shape of the mold 2 by attaching the attachment 6 .
Next, after a cold material, a sealing material, etc. are provided above the dummy bar head 5 and between the dummy bar head 5 and the mold 2, molten steel is poured into the mold 2 to start continuous casting. In the present embodiment, by adjusting the shape of the corner portion 51 using the attachment 6, even with one dummy bar head 5, two types of molds 2 (the first mold 2A and the second mold 2B), the gap between the mold 2 and the dummy bar head 5 can be appropriately managed. Therefore, it is possible to improve the sealing performance during continuous casting.
After the continuous casting is started, the cast slab is pulled out by the dummy bar 4. - 特許庁After the slab is pulled out to a predetermined position, the slab is separated from the dummy bar 4 and continuous casting is continued.

A steel slab cast by continuous casting becomes a steel slab product as it is, or a steel slab obtained by continuous casting is subjected to further post-treatment to become a steel product.
The post-treatment includes all post-treatments in steel product manufacturing plants such as steel mills, where slabs are used as starting materials. For example, finishing treatment such as removing scratches on slabs, hot working using slabs (hot forging and hot rolling of slabs, hot rolling of steel plates, steel pipes, and long bars) and cold working Processing (manufacturing processes such as cold rolling, cold drawing, etc., including those after hot working), heat treatment for steel that has been subjected to these hot working treatments and cold working treatments, and furthermore, these Hot working treatment, cold working treatment, processing involving welding of steel obtained by heat treatment to materials (manufacturing process of welded pipes and welded H-shaped steel, etc.) and surface treatment of materials (including plating and coating) manufacturing process of steel), finishing treatment of steel obtained through any of these post-treatments, inspection treatment, and the like. Specific examples of steel products that are finally obtained through post-treatment include steel bars, steel wire rods, thick steel plates, shaped steel, hot-rolled steel plates, cold-rolled steel plates, steel pipes, and the like, which are further subjected to plating and film formation. Examples include plated steel, coated steel, and the like.

<Modification>
Although the invention has been described with reference to particular embodiments, it is not intended that the invention be limited by these descriptions. Along with the disclosed embodiments, other embodiments of the invention, including various modifications, will be apparent to persons skilled in the relevant art(s) upon reference to the description of the invention. Therefore, the embodiments of the invention set forth in the claims should be construed to cover the embodiments that include these variations described herein singly or in combination.

For example, in the above embodiment, the mounting mechanism of the attachment 6 to the dummy bar head 5 is bolting, but the present invention is not limited to such an example. A mechanism for attaching the attachment 6 to the dummy bar head 5 is capable of withstanding shock, vibration, etc. when the dummy bar head 5 is inserted into the continuous casting machine 1, and does not come off the dummy bar head 5 during continuous casting. Any other mechanism may be used.

Further, in the above embodiment, the corner portion 51 of the dummy bar head 5 is chamfered at 45°, but the present invention is not limited to such an example. The shape of the corner portion 51 can be a shape chamfered at an angle different from 45°, a shape chamfered at an angle different from 45°, or a shape chamfered with an R as long as it can be inserted into the first mold 2A and an appropriate clearance is formed in the mold corner portion 21A. Other shapes such as shape may be used. In these cases, the surface of the attachment 6 that contacts the corner portion 51 also has a shape corresponding to the corner portion 51 .

Moreover, in the above-described embodiment, the mold corner portion 21B of the second mold 2B is not chamfered, but the present invention is not limited to such an example. The second mold 2B may have a shape in which the mold corner portions 21B are chamfered by a smaller chamfering amount than the corner portions 21A of the first mold 2A. Furthermore, a configuration may be adopted in which another mold 2 is further used in which the amount of chamfering of the mold corner portions 21 is less than that of the first mold 2A and greater than that of the second mold 2B. In this case, attachments 6 that match the shape of corner portions 21 of other molds 2 can be attached to dummy bar heads 5 .
Furthermore, in the above embodiment, the slab cast by continuous casting is a billet or a bloom, but the present invention is not limited to such examples. The slab may have a corner portion with an angle of about 90° when viewed from the casting direction, and may have other shapes such as a slab, for example.

<Effects of Embodiment>
(1) The dummy bar 4 of the continuous casting machine 1 according to one aspect of the present invention includes a first mold 2A having a chamfered mold corner portion 21A, and a non-chamfered mold corner portion 21B or a chamfered mold corner portion 21B. In a continuous casting machine 1 for steel, in which at least two types of molds 2 of a second mold 2B chamfered by a chamfering amount smaller than that of the first mold 2A are used interchangeably, the continuous casting machine 1 used at the start of continuous casting The dummy bar 4 is provided with a dummy bar head 5 that is inserted into the mold 2 of the continuous casting machine 1 at the start of continuous casting. It has a chamfered shape according to the shape of the mold corner portion 21A of the mold 2A of No. 1, and an attachment 6 for reducing the amount of chamfering of the corner portion 51 can be attached to the corner portion.

According to the above configuration (1), in a continuous casting machine that uses at least two types of molds 2 that are different only in the shape of the mold corner portions 21, the shape of the dummy bar head 5 can be changed without exchanging the dummy bar head 5. can be changed. Further, since the shape of the corner portion 51 can be changed only by attaching the attachment 6 to the dummy bar head 5, the shape can be changed easily and inexpensively.

(2) In the configuration of (1) above, the dummy bar head 5 has a rectangular shape when viewed from the direction of insertion into the casting mold, and the attachment 6 is attached to the dummy bar head 5 and attached to the dummy bar head 5. The long sides of the rectangular shape are located inside the dummy bar head 5 .
According to the configuration (2) above, since the roll 3 and the attachment 6 do not come into contact with each other, deformation and damage of the attachment 6 due to the pressing force of the roll 3 can be prevented.

(3) A steel continuous casting method according to an aspect of the present invention includes a first mold 2A having a chamfered mold corner portion 21A and a mold corner portion 21B that is not chamfered or a mold corner portion 21B that is not chamfered. A continuous casting method for steel using at least two different molds 2 of a second mold 2B chamfered with a smaller chamfering amount than the mold 2A, wherein at the start of continuous casting, the above (1) or ( When continuous casting is performed with the first mold 2A using the dummy bar 4 of the continuous casting machine 1 configured in 2), continuous casting is performed with the second mold 2B using the dummy bar 4 with the attachment 6 removed. In that case, the dummy bar 4 with the attachment 6 attached is used.
According to the configuration of (3) above, the same effects as those of (1) or (2) above can be obtained.

(4) A method for producing a steel slab according to an aspect of the present invention produces a steel slab by the continuous steel casting method having the configuration of (3) above.
According to the configuration of (4) above, with the effect of (1) above, steel slabs can be manufactured inexpensively and easily. Further, if the dummy bar 4 having the structure of (2) is used, the steel slab can be produced at a lower cost due to the effect of (2).

(5) A method for manufacturing a steel product according to an aspect of the present invention provides a product by subjecting the slab cast by the continuous steel casting method of the above (3) to a post-treatment.
According to the configuration of (5) above, the effect of (3) above makes it possible to produce steel slabs at low cost. The manufacturing cost can be reduced by the amount of the reduction in the manufacturing cost of the slab.

Next, an example conducted by the inventors will be described. In the examples, continuous casting was performed in two types of molds 2, a first mold 2A and a second mold 2B, using the same dummy bar 4 as in the above embodiment. For both the first mold 2A and the second mold 2B, the maximum length (width) in the long side direction of the casting space was set to 400 mm, and the maximum length (thickness) in the short side direction was set to 310 mm. . In addition, in the first mold 2A, the casting space was chamfered at 45° (chamfered by 25 mm in the width direction and 25 mm in the thickness direction) in the mold corner portion 21A. Further, as shown in FIG. 4 , the surface of the attachment 6 on the long side of the dummy bar head 5 is arranged inside the dummy bar head 5 . As the continuous casting machine 1, a curved continuous casting machine was used.

In the examples, when continuous casting was performed using the first mold 2A, continuous casting was started using the dummy bar 4 with the attachment 6 removed from the dummy bar head 5 . When continuous casting was performed using the second mold 2B, continuous casting was started using the dummy bar 4 with the attachment 6 attached to the dummy bar head 5 .
As a result of the examples, in the casting of any mold 2, the insertion of the dummy bar 4 into the continuous casting machine 1 and into the mold 2 could be carried out without any problem. Also, it was confirmed that there was no problem with the sealing performance between the dummy bar head 5 and the mold 2 . Furthermore, it was confirmed that the attachment 6 was neither deformed nor damaged due to the reduction of the roll 3 .

REFERENCE SIGNS LIST 1 continuous casting machine 2 mold 2A first mold 2B second mold 21, 21A, 21B mold corner portion 3 roll 4 dummy bar 5 dummy bar head 51 corner portion 52 connecting portion 511 connection hole 6 attachment 61 mounting hole 7 bolt

Claims (4)

A first mold in which the mold corners are chamfered, and a second mold in which the mold corners are not chamfered or the mold corners are chamfered by a chamfer amount smaller than that of the first mold.
A dummy bar of a continuous casting machine used at the start of continuous casting in a continuous steel casting machine that uses at least two types of molds of
A dummy bar head inserted into the mold of the continuous casting machine at the start of the continuous casting,
The dummy bar head has a shape in which a corner portion corresponding to the mold corner portion is chamfered according to the shape of the mold corner portion of the first mold , and when viewed from the insertion direction into the mold An attachment that has a rectangular shape and reduces the amount of chamfering of the corner can be attached to the corner ,
The attachment is a dummy bar of a continuous casting machine, wherein the surface of the rectangular long side of the dummy bar head is located inside the dummy bar head when attached to the dummy bar head . At least two types of a first mold in which the mold corners are chamfered, and a second mold in which the mold corners are not chamfered or the mold corners are chamfered by a smaller chamfering amount than the first mold. A continuous casting method for steel that uses the mold of
At the start of continuous casting, using the dummy bar of the continuous casting machine according to claim 1 ,
When performing the continuous casting with the first mold, using the dummy bar with the attachment removed,
A continuous casting method for steel, wherein the dummy bar with the attachment attached is used when the continuous casting is performed with the second mold. A method for producing a steel slab by the continuous steel casting method according to claim 2 . A method for producing a steel product, comprising subjecting a slab cast by the continuous steel casting method according to claim 2 to a post-treatment to obtain a steel product.

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