JPH07144255A - Vertical semicontinuous casting device for large cross section cast slab and carrying out method of cast slab - Google Patents

Abstract

PURPOSE:To obtain a vertical semicontinuous casting device of simple structure and suitable for small quantity production by constituting so that a cast slab completed solidification is pulled up above mold. CONSTITUTION:A large cross section cast slab 10 is cast by a mold 1. A cast slab 10 is guided vertically and downward by a cast slab supporting roll 2. A dummy head 8 is arranged below the cast slab. The dummy head 8 is held by a carriage 7 having a dead weight surpassing the drawing resistance of cast slab. The carriage 7 is guided up/down direction by a guide 9. The carriage 7 is pulled up by a winch mechanism consisting of a wire 5, drum shaft 6, etc. The cast slab 10 completed solidification is pulled up by using these. By this method, a large cross section cast slab is easily carried out even in restricted space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical type semi-continuous casting apparatus for producing large-section slabs for small-lot production, and slabs for slabs even when the head of an overhead crane is insufficient due to building restrictions. The present invention relates to a transportation method that can be moved.

[0002]

2. Description of the Related Art The widespread use of continuous casting operations in the steel manufacturing industry has greatly contributed to cost rationalization in terms of yield improvement, energy saving and labor saving. However, the ordinary ingot making method is still applied to extremely thick steel plates, which are difficult to be continuously cast due to dimensional constraints, and small lot production forgings. In the ordinary ingot making method, various techniques for so-called semi-continuous casting have been proposed for producing large-section steel ingots as continuously as possible.

FIG. 1 is a schematic explanatory view showing the structure of a conventional typical vertical type semi-continuous casting apparatus, and FIG. 2 is a line II-II of FIG.
FIG. The apparatus shown in both figures has a pair of roller units 20a for supporting a slab on each of a long side and a short side;
20b, 21a; 21b, one of the long side roller units 20a; 20b is configured to be capable of tilt drive (arrow A), and a cast slab C is provided.
It was made possible to carry out. Further, in this device, the dummy bar head 23, the supporting member 24, the winch 2 for insertion,
5, a pull-out winch 26, wires 27, 28, etc., and a dummy bar head 23 in the slab support device 22.
This is a configuration in which a winch type dummy bar mechanism 29 for vertically moving the is provided. In FIGS. 1 and 2, 31 is a ladle, 32 is a mold,
33 is a pit, 36 is a discharge table, 37
Is a spray for secondary cooling, 38 is a slab supporting body, 39 is a supporting frame, 40 is an oscillation device, and 41 is an air cylinder.

In the above-mentioned apparatus, roller units 20 and 21 are provided as the slab supporting device 22, and the roller units 20 and 21 are tilted along one side to carry out the slab. Therefore, the roller is required over substantially the entire length of the cast slab C, and a drive device for tilting is also required. Further, since the slab is tilted in the pit 33, a large space for the pit 33 is also required. Further, the winch type dummy bar mechanism 29 requires two systems of winches, an insertion winch 25 and an extraction winch 26.

As techniques for semi-continuous casting, in addition to the apparatus shown in the drawings, various types such as the following have been proposed, but all have problems. As one of them, a vertical type semi-continuous casting apparatus is constituted by a water cooling mold and a slab supporting grid below the mold, and after casting the molten metal to a predetermined length, while supporting the side surface of the steel ingot with the grid. There is a technique in which the lower the steel ingot, the stronger it is cooled, and the solidified one is successively solidified from the lower part of the steel ingot (for example, Japanese Patent No. 1594742).
issue). In addition, there is also proposed a technique of performing heat insulation (or heating) from the head of the steel ingot to the lower portion, allowing it to cool, and strongly cooling it, and performing strong cooling toward the lower portion of the steel ingot (for example, Japanese Patent Publication No. 3-29497).
issue). However, in these techniques, the temperature gradient between the longitudinal direction of the slab and the direction orthogonal to it becomes large, and when the slab cross-sectional area is large, the occurrence of residual stress becomes remarkable, and the slab cracks, resulting in a sound steel ingot. There is a problem that can not be obtained. Such a tendency becomes greater as the slab cross-section size increases.

On the other hand, a technique of reciprocating the support roll and the spray nozzle along the slab drawing direction has been proposed (for example, Japanese Patent Laid-Open No. 57-64464), but in order to reciprocate the support roll and the spray nozzle. Mechanism is required, and the device configuration becomes complicated.

In addition, (1) a technique in which the lower portion of the steel ingot is strongly cooled, solidification proceeds from the lower portion of the steel ingot, and compression deformation is performed immediately after the completion of solidification (Japanese Patent Laid-Open No. 63-33163), (2) With a support frame A technique for supporting the side surface of a steel ingot and applying further reduction (Japanese Patent Laid-Open No. 63-180351), (3) Narrowing the slab during solidification, and gradually increasing the degree of narrowing as the solidified shell thickness increases. A technique for completing solidification of a slab while allowing it
No. 278653), and (4) techniques such as applying pressure corresponding to the shrinkage of the solidified shell from not only the long side of the slab but also the corner side (Japanese Patent Laid-Open No. 63-238964) have been proposed. However, both require equipment for rolling down large-section slabs.

[0008]

As described above, all of the techniques proposed so far have the drawbacks that the device configuration becomes complicated and large, and the equipment cost increases. In the conventional technology related to the production of large cross-section cast slabs as described above, the facility structure can be said to be considerably simplified as compared with a general continuous casting machine, but as a facility for small-scale production of several thousand tons per month. However, a sufficient investment effect cannot be expected, and it is expected that the facility cost will be reduced with a simpler facility structure.

The present invention has been made to solve the technical problems in the prior art, and its object is to provide a structure of a vertical type semi-continuous casting apparatus having a simpler structure and suitable for small-volume production. To provide. Another object of the present invention is to solve the problem of slab unloading of the apparatus shown in FIGS. 1 and 2 and to easily unload a large-section slab even in a relatively narrow space. To provide a method.

[0010]

Means for Solving the Problems The apparatus of the present invention that achieves the above objects comprises a mold for casting a large-section cast slab, a slab support roll for guiding the slab vertically downward, and a slab lower side. In the vertical type semi-continuous casting apparatus for producing a large-section cast product having a dummy head provided in, and a spray for secondarily cooling the outer periphery of the cast product, while holding the dummy head, the self-weight which exceeds the pull-out resistance of the cast product A large section having a gist in that it has a carriage having a guide, a guide for vertically guiding the carriage, and a wire winch mechanism for pulling up the carriage, and is configured to pull up a solidified slab above a mold. It is a vertical semi-continuous casting apparatus for producing cast slabs.

The present invention also provides a device as described above,
The mold and slab support roll are integrated into a structure that can be retracted in the horizontal direction, and the main point is that the side surface of the upper half of the casting device is open. By adopting the method, after the solidification of the slab is completed, the mold and the slab support roll are retracted horizontally, and then the slab is pulled up to the upper half of the casting device, and then it can be moved horizontally from the open side surface. it can.

[0012]

The apparatus according to the present invention is constructed as described above. In short, the wire winch mechanism pulls up the carriage holding the dummy head to insert the slab of the dummy head, and the carriage is removed. The wire winch mechanism is equipped with only one system, because the wire weight is loosened according to the casting speed so that the wire is lowered along with the carriage guide guide by making its own weight exceed the pull-out resistance of the slab. It is possible to simplify the structure of the slab drawing apparatus. On the other hand, after solidification is completed, the slab can be pulled up by the wire winch and lifted up to unload the slab, and the slab unloading mechanism and the pit for tilting the slab, etc. Becomes unnecessary.

By the way, when the slab cannot be carried out upward due to a building restriction, the slab is carried out by digging a deep pit like the device shown in FIGS. However, there arises a problem that the equipment cost becomes high. In such a case, the mold and the slab support roll are integrated so that they can be moved in the horizontal direction, and one surface of the upper part of the frame of the continuous casting machine can be opened to the extent that the lift of the overhead crane is insufficient. This eliminates the need for the tilting device, the deep carry-out pit, and the like as described above, so that the facility cost can be minimized from this point of view.

In casting with the apparatus of the present invention, molten steel is first poured from a ladle or tundish into a mold. It is preferable because it can be poured and the tundish can be omitted, so that the initial cost and running cost can be reduced.

The production of a cast product using the apparatus of the present invention is carried out, for example, as follows. First, the casting speed is slowed down to 0.2-1 liter / kg · steel.
It is possible to prevent internal cracks due to bulging by strong cooling with the slab, so there is no need to install a slab support roll over the entire length of the slab, and only a few stages directly below the slab are required. Can be greatly simplified. From this viewpoint, the casting speed is 0.01 to 0.15 m /
It is preferably set to min.

By controlling the surface temperature by adjusting the amount of secondary cooling water during casting and performing slow cooling of the cast piece after casting, it is possible to alleviate the occurrence of residual stress and prevent cracking of the cast piece. From this point of view, the amount of secondary cooling water is preferably set so that the surface temperature of the slab directly below the foot roll is in the range of 400 to 1000 ° C. After the casting is completed, the hot top is performed until the slab is completely solidified, whereby shrinkage of the slab head can be prevented and a slab with a good yield can be obtained. Specific procedures for such a hot top include, for example, the following methods (1) and (2).

(1) After the casting is completed, the secondary cooling spray is stopped and the slab is air-cooled, and the slab is immediately pushed up on the mold for a predetermined length, and the side surface of the top of the slab is surrounded by a heat insulating and heat-insulating frame to provide immediate effect. An exothermic heat-retaining agent and a slow-acting heat-retaining heat-retaining agent are added in this order, or a self-fluxing flux is added to conduct electric heating, and hot top is performed until the solidification of the slab is completed. (2) Immediately after the completion of casting, the slab is pushed up by a predetermined length onto the mold, and the heat insulating heat insulating frame surrounds the top surface of the slab to provide immediate-acting heat-retaining agent and slow-acting heat-retaining agent in this order. Add or add a self-fluxing flux and heat by energization, and adjust the amount of secondary cooling water so that the surface temperature does not fall below 400 ° C. and perform hot top until the solidification of the slab is completed.

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modification of the present invention can be made without departing from the spirit of the preceding and following paragraphs. It is included in the technical scope.

[0019]

EXAMPLE FIG. 3 is a schematic explanatory view showing an example of a vertical semi-continuous casting apparatus of the present invention, in which 1 is a mold, 2 is a foot roll (cast piece support roll), and 3 is mold vibration. Frames 4a, 4b are spray nozzles, 5 are wires, 6 is a drum shaft, 7 is a carriage, 8 is a dummy head, 9
Is a carriage guide, 10 is a cast piece, 11 is a ladle, 12 is a slide valve, 13 is an immersion nozzle, and 14 is a pulley.

In this apparatus, a foot roll 2 for supporting a slab in two stages (two stages in the figure) and spray nozzles 4a, 4b for secondary cooling are arranged immediately below a mold 1 and hold a dummy head 8. The carriage 7 is suspended by a single wire 5 via a pulley 14 so that both edges of the wire 5 are fixed to the drum shaft 6, and the drum shaft 6 is normally or reversely rotated along a carriage guide 9. Thus, the dummy winch 8 can be moved up and down by a one-line wire winch mechanism. An example of the main specifications of the apparatus shown in FIG. 3 is shown below.

(Example of main specifications) Mold size: 700 ^T x 700 to 1400 ^W x 400 ^L
(Variable width) Mold vibration: frequency 0 to 30 cpm, amplitude ± 2 mm Casting speed: 0.01 to 0.15 m / min Foot roll: 2 stages Secondary cooling: spray type, specific water volume 0.2 to 1.0 liter / Kg ・ steel slab drawing mechanism: wire winch type

A procedure for producing a large-section cast piece using this apparatus will be described with reference to the drawings (FIGS. 4 to 7). First, the dummy head 8 is inserted and set at a predetermined position under the mold 1, and the ladle 1
After opening the nozzle of No. 1, ladle 11 while holding molten steel by Ar blowing from the slide plate of slide valve 12
On the mold. After mounting the immersion nozzle 13, the molten steel M is directly poured into the mold 1, and while controlling the pouring amount with the slide valve 12, the secondary cooling water has a surface temperature of 500 ° C. of the cast piece 10 under the foot roll 2. To adjust
The casting is completed by loosening the wire at a constant speed and pulling out the slab according to a predetermined casting speed (FIGS. 4 and 5). The casting speed in this case needs to be set according to the cross-sectional dimension of the slab so that the slab does not cause bulging at the mold outlet,
For example, in the case of 700 mm square, casting is performed at 0.1 m / min.

Immediately after the casting is completed, the carriage 7 is immediately lifted to push the slab up to the mold by about 500 mm, the slab is surrounded by the heat insulation and heat insulation frame 16, and the self-fluxing flux is quickly added to the slag head to slag 17. And the electrode 18 is set and electroslag hot topping is performed until the solidification of the residual molten steel in the slab is completed (FIG. 6). After the solidification is completed, the foot roll 2 guides the slab to prevent it from coming into contact with the slab, and the carriage 7 further pulls it up onto the slab. (Fig. 7).

The inventors of the present invention used the device shown in FIG. 3 and performed the procedure shown in FIGS.
When a square medium carbon steel slab was manufactured and its internal quality was investigated, it was found that there was no internal cracking, and that the reverse V segregation, center segregation, and the amount of inclusions were better than those of ordinary steel ingots of the same weight. It was confirmed. FIG. 8 is a schematic explanatory view showing another embodiment of the device of the present invention. The basic configuration of this device is shown in FIG.
It is similar to that shown in FIG. 3 and corresponding parts are assigned the same reference numerals to avoid redundant description.

In this apparatus, the foot roll 2 is integrated with the mold 1 and is suspended on the mold carriage 15 so that it can be retracted in the horizontal direction. In carrying out the slab 10 using such a device, a hot top is carried out after the completion of casting, the mold 1 and the foot roll 2 are evacuated by the mold carriage 15 after complete solidification, and the slab carrying-out side device upper half is carried out. The slab 10 has a structure that can be opened partially,
Then, the slab is pulled up to the upper half of the apparatus by the slab hanger 46 as shown in FIG. 9, and the slab is horizontally moved to a wide upper region, and then the slab is overturned and further transported upward. When retracting the mold carriage 15, the slab 1
It is necessary to remove the mold 1 and the foot roll 2 from the upper part of 0. For example, temporarily lower the cast piece to the bottom of the foot roll to escape the dolly, or suspend the mold and the foot roll on the mold dolly and lift the dolly. This can be achieved by adopting a structure in which the foot roll is pushed up above the upper end of the cast slab.

By adopting such a configuration, it becomes possible to manufacture the required long slab even if the crane head is insufficient due to the building restrictions. Although the embodiment shown in FIGS. 3 and 5 is provided with the mold vibrating device to gradually pull out the slab, the device of the present invention employs the carriage 7 having its own weight exceeding the slab pulling resistance. Therefore, the mold vibrating device as described above can be omitted, and mechanical equipment and electrical restriction equipment relating to mold vibration are not required, and the equipment cost can be reduced.

[0027]

The present invention is constructed as described above, and has realized a vertical semi-continuous casting apparatus having a simple structure and suitable for small-quantity production. Moreover, it has become possible to easily carry out a large-section slab in a limited space.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a structure of a conventional typical vertical type semi-continuous casting apparatus.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a schematic explanatory view showing an example of a vertical semi-continuous casting apparatus of the present invention.

FIG. 4 is an explanatory view showing a state where a large-section cast slab is being cast.

FIG. 5 is an explanatory view showing a state where casting is completed.

FIG. 6 is an explanatory diagram showing a state where electroslag hot topping is being performed.

FIG. 7 is an explanatory view showing a state of pulling up a slab that has completed solidification.

FIG. 8 is a schematic explanatory view showing another embodiment of the device of the present invention.

FIG. 9 is a diagram for explaining how a cast slab is carried out using the device of the present invention.

[Explanation of symbols]

 1 Mold 2 Foot Roll 4 Spray Nozzle 5 Wire 7 Carriage 8 Dummy Head 9 Carriage Guide 10 Cast Slab 11 Ladle

(72) Inventor Keisuke Tanaka 2-3-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Takasago Works, Kobe Steel Co., Ltd. Kobe Steel, Ltd. Takasago Works (72) Inventor Tatsuya Ikoma 2-3-1, Niihama, Arai-cho, Takasago-shi, Hyogo Pref. No. 3-1 Takasago Works, Kobe Steel, Ltd.

Claims (3)

[Claims] 1. A mold for casting a large-section slab, a slab support roll for guiding the slab vertically downward, a dummy head provided below the slab, and an outer periphery of the slab for secondary cooling. In a vertical-type semi-continuous casting apparatus for producing a large-section cast product having a spray, while holding the dummy head, a carriage having a self-weight that exceeds the pull-out resistance of the cast product, and a guide for guiding the carriage in the vertical direction, A vertical semi-continuous casting apparatus for producing a large-section cast piece, which has a wire winch mechanism for pulling up a carriage and is configured to pull up a cast piece that has completed solidification above a mold. 2. The vertical semi-continuous casting apparatus according to claim 1, wherein the mold and the slab support roll are integrated into a structure capable of retracting in the horizontal direction and the side surface of the upper half of the casting apparatus is opened. A vertical semi-continuous casting apparatus characterized by having a structure. 3. The apparatus according to claim 2, wherein after the solidification of the cast slab is completed, the mold and the cast slab supporting roll are retracted in the horizontal direction, and then the cast slab is pulled up to the upper half of the caster, and thereafter. A method for carrying out a slab characterized by moving horizontally from the open side surface.