JPH0318537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a continuous casting apparatus for continuously casting thin metal sheets by jetting molten metal onto the surface of a rotating roll through a nozzle.

[Background of the invention]

Conventional continuous casting equipment for metal plates includes equipment as shown in FIG. 1 or 2. FIG. 1 shows a continuous casting apparatus for metal plates using a method called the single roll method, in which only one rotating roll is used. Nozzle body 1
The raw material 2 inside is heated by a work coil 3, and the heated and melted molten metal 4 is ejected onto the surface of a rotating roll 5. Ejection is performed by applying gas pressure into the nozzle body 1. The ejected molten metal 4 is cooled and solidified to continuously form metal plates 6.

FIG. 2 shows an apparatus in which there are two rotating rolls, and a forming roll 7 is further installed in addition to the rolls in FIG. 1. This forming roll 7 is used to improve the surface precision of the metal plate 6.

3 and 4 show a front sectional view and a bottom view of the conventional nozzle body 1 used in FIG. 1 or 2, respectively. Generally, the opening 8 of the nozzle body 1 has a rectangular shape, with the long side determining the width of the metal plate to be cast, and the short side determining the same thickness.

The metal plate cast by the conventional casting apparatus described above is called a billet bloom, and its shape is limited to a thickness and width of about 10 mm or more. In the case of automobile steel plates, stainless steel plates, brass plates, copper plates, aluminum plates, etc., thin plates with a thickness of 1 mm or less are produced by rolling and annealing the bloom, and repeating the rolling process to make the plates thinner.

Therefore, if a thin metal plate (with a thickness of about 1 mm or less) can be manufactured by continuous casting, the above-mentioned process can be omitted, which is very advantageous from the viewpoint of energy saving and low cost.

[Problems with background technology]

However, the reason why there is no conventional continuous casting apparatus for thin metal sheets is because of various problems. One of the problems is that surface accuracy (uniform thickness and width) of the metal thin plate cannot be obtained. Japanese Patent Publication No. 57-398615 is known as a prior art for solving this problem. In this conventional technology, in order to widen the width of the molten metal flowing down from the pouring nozzle, the molten metal flows down onto the swash plate below the pouring nozzle, and in order to widen the width, a gas jet nozzle is connected to the swash plate. The width of the molten metal stream is widened by installing a gas stream into the molten metal stream. However, with this conventional technique, a molten metal flow with a uniform thickness cannot be obtained, and therefore a thin metal plate with a uniform thickness cannot be obtained. Therefore, the problem of surface accuracy of thin metal plates remains a very serious problem. Furthermore, in conventional continuous casting equipment, when manufacturing thin plates of about 0.5 mm, there was a problem in that the nozzle was clogged and continuous casting could not be performed.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a continuous thin metal plate casting apparatus that can make the thickness of a molten metal flow uniform and continuously cast metal thin plates having a uniform thickness.

[Idea for the invention]

In order to improve the surface accuracy of the thin metal plate, the inventor
In particular, in order to make the thickness uniform, various experiments were conducted using stainless steel, copper alloy, etc. as the metal raw material. First, using a normal roll and a normal nozzle, we investigated the roll rotation speed, molten metal ejection pressure, ejection amount, etc. As a result, the following findings were made clear.

(1) The thickness of the metal sheet increases as the roll rotation speed is slowed down, and the uniformity of the thickness further deteriorates.

(2) If the roll rotation speed is slowed down, some of the molten metal ejected from the nozzle will scatter in the opposite direction to the roll rotation direction. As a result, the molten metal pool formed between the nozzle tip and the roll surface becomes unstable, making it impossible to obtain a thin plate with uniform thickness. Further, at this time, the yield of casting becomes poor.

(3) There is a limit to the thickness of the metal plate; if the thickness exceeds a certain value, the molten metal will flow in the width direction of the metal plate, resulting in uneven thickness.

(4) In order to reduce the thickness of the metal sheet, it is necessary to reduce the size of the opening at the tip of the nozzle, but if it is made smaller, the molten metal will clog and continuous casting will no longer be possible.

From the above, it has been found that conventional nozzles cannot produce thin metal plates with non-uniform thickness. Therefore, in order to obtain more detailed information, the behavior of molten metal during continuous casting using the conventional rolls and nozzles, such as the molten metal pool and the solidification process of molten metal, was projected and analyzed using a high-speed camera.

The analysis results of this high-speed photography will be explained with reference to FIGS. 5 to 8.

FIG. 5 shows the behavior of molten metal ejected from the conventional nozzle 1 shown in FIGS. 3 and 4. In this way, the molten metal 4 ejected from the conventional nozzle 1 falls vertically downward. FIG. 6 schematically shows the ejection behavior when molten metal is ejected onto the surface of the rotating roll 5 by the nozzle 1 shown in FIG. 5, taken with a high-speed camera. molten metal 4
A part of the particles is also scattered in the opposite direction to the rotation direction of the roll 5. This is due to the imbalance between the amount of molten metal 4 ejected and the rotational speed of the roll 5. That is, this occurs because the roll rotation speed is slow relative to the ejection amount. When such a scattering phenomenon occurs, the molten metal pool formed between the tip of the nozzle 1 and the surface of the roll 5 becomes unstable, and as a result, it goes without saying that a thin metal sheet with a uniform thickness cannot be manufactured.
The yield of thin metal sheets also deteriorates.

In order to prevent the above phenomenon, the rotation speed of the roll 5 may be increased. However, the thickness of the metal sheet depends on the rotation speed of the roll 5, and
As the rotational speed of the roll 5 increases, the thickness of the metal sheet decreases, and conversely, as the rotational speed of the roll 5 decreases, the thickness increases. For this reason, if the rotational speed of the roll 5 is increased, it becomes impossible to cast a thin metal plate with a desired thickness.

Therefore, as a result of considering various conditions to prevent the above-mentioned phenomenon without increasing the roll rotation speed, we found that
The molten metal ejected from the nozzle 1 is ejected at an angle in the rotation direction of the roll 5, and the setting position of the nozzle 1 is shifted from directly above the center of the rotation axis of the roll 5 to the side in the roll rotation direction (to the right in the figure). Alternatively, as shown in FIG. 7, by lengthening the stroke L of the opening of the nozzle 1 to incline the jet of molten metal in the direction of rotation of the roll blank, the molten metal can be ejected in the opposite direction to the rotation direction of the roll 5. It was found that scattering can be prevented.

However, in order to suppress the surface accuracy of the thin metal plate, the distance from the surface of the roll 5 to the tip of the nozzle 1 must be set strictly. Therefore, in the method of tilting the nozzle 1 described above, the distance between the opening 8 of the nozzle 1 and the surface of the roll 5 is
The surface is not uniform due to the slope, which is not preferable. In addition, the method of lengthening the opening stroke L is advantageous over the method in that there is no need to tilt the nozzle, but since the stroke L is long, the molten metal clogs the nozzle, making continuous casting impossible. It is. In addition,
In order to prevent nozzle clogging, the stroke L may be shortened as shown in FIG. 8, but in this case, the injected molten metal would fall vertically as in the conventional case shown in FIG. 5.

As a result, it was found that the structure of the nozzle is important in producing a thin metal plate with uniform thickness.

[Summary of the invention]

Therefore, the nozzle in the continuous thin metal sheet casting apparatus of the present invention has an opening in the internal bottom surface (corresponding to the nozzle tip) of the nozzle body, and this internal bottom surface has an inclined surface toward the opening in the roll rotation direction. Among these inclined surfaces, the angle between the front inclined surface in the roll rotation direction and the roll tangent is larger than the angle between the rear inclined surface in the roll rotation direction and the roll tangent.

Since the molten metal ejected by the above structure is ejected along the front and rear inclined surfaces, it is not ejected directly below the nozzle, but is ejected obliquely toward the roll rotation direction. This prevents the molten metal from scattering in the direction opposite to the roll rotation direction, and the molten metal pool formed between the nozzle tip and the roll surface also becomes stable.

〔Example〕

<First Example> A first example of the present invention will be described with reference to FIG. The nozzle body 1 has an opening 8 on the inner bottom surface, and this inner bottom surface has an opening 8 in the rotation direction of the roll 5.
It forms an inclined surface towards. The angle α between the front inclined surface in the roll rotation direction and the tangent to the roll 5 is larger than the angle α' between the rear inclined surface in the roll rotation direction and the tangent to the roll 5. This embodiment does not have an opening stroke L as shown in FIG. 7, and the molten metal will not clog the nozzle. The ejected molten metal is ejected obliquely in the direction of rotation of the roll 5. 1st
Figure 0 shows the flow of the molten metal blank on the roll 5 when the nozzle 1 of this embodiment is used.

Using the nozzle of this first embodiment, a thin metal plate was cast using 50 g of stainless steel (SUS304 steel) as the raw material for the thin metal plate under the casting conditions shown below. The nozzle was made of quartz, the dimensions of the opening were 1 mm x 10 mm, and the angle of the slope was 45 degrees for α and 30 degrees for α'. roll diameter
300mm alloy tool steel (SKD-61 steel) was used. The rotation speed of the roll is 4 m/s, and the molten metal ejection temperature is
The temperature was 1490°C, and the molten metal injection pressure was 0.7 Kg/cm ² .
As a result, a thin metal plate with a thickness of 0.5 mm and a width of 13 mm was cast. Since the molten metal is ejected obliquely in the direction of rotation of the rolls, it is unlikely to be scattered in the direction opposite to the direction of rotation of the rolls even if the rotation speed of the rolls is slow. Therefore, thin metal plates having uniform thickness and good surface accuracy can be continuously cast.

<Second and Third Embodiments> The present invention is realized by the shape of the inner and inner bottom surfaces of the nozzle body, and even if the external shape of the nozzle is as shown in FIG. 11 or FIG. I don't mind.

FIG. 13 shows the relationship between the roll rotation speed and the amount of molten metal ejected by comparing the nozzle according to the above embodiment and the nozzle of the conventional device. The shaded range in the figure is a proper casting range in which molten metal does not scatter in the direction opposite to the roll rotation direction. This shows that by using the nozzle of the above embodiment, proper manufacturing is possible even if the amount of molten metal is ejected approximately twice as much as that of the conventional nozzle.

<Fourth Embodiment> The above embodiment takes into account the structure of the nozzle that determines the thickness of the thin metal plate 6' to be cast, but the fourth embodiment shown in FIGS. 17 to 19 The nozzle structure is taken into consideration to determine the width dimension of 6'.

First, the width dimension of the conventional thin metal plate 6' will be explained. FIG. 14 shows the amount of molten metal ejected from a nozzle having a conventional shape (FIGS. 3 and 4) and the thickness and width dimensions of a thin metal plate to be cast. In this conventional example, the roll rotation speed is 3.9 m/s, and the gap size from the nozzle tip to the roll surface is 0.5 mm. The short side of the nozzle opening is 0.5 mm and the long side is 5 mm. As can be seen from the figure, the thickness of the cast metal sheet (marked with a circle in the figure) is approximately 0.5 mm and constant, but the width (marked with a circle in the figure) increases as the amount of molten metal ejected increases. are doing. FIG. 15 schematically shows this phenomenon of increasing width from the front in the roll rotation direction. FIG. 16 is a schematic cross-sectional view of the cast thin metal plate 6' taken from a photograph. In this cross-sectional view, the thin metal plate 6'
Both edges are thin and not uniformly thick. Therefore, both end portions cannot be used, resulting in poor yield. Furthermore, since both ends must be cut, casting of the thin metal sheet involves a cutting process, which increases the cost.

Therefore, as shown in FIG. 17, the rear and lateral sides of the edge of the nozzle opening in the roll rotation direction protrude and extend to the vicinity of the surface of the roll 5, and the shape and dimensions of the gap between the front edge of the opening and the surface of the roll 5 are adjusted to 6'
The cross-sectional shape and dimensions of the That is, a gap having substantially the same shape as the thickness T and width W of the thin metal plate to be cast is provided at the bottom of the nozzle. Note that FIG. 18 shows a longitudinal sectional view of FIG. 17. Further, FIG. 19 shows a front view of FIG. 17.

Using the nozzle of the fourth embodiment shown in FIG. 17, a thin metal plate was cast using 50 g of Cu-12% Al alloy as the raw material for the thin metal plate. Nozzle 1 is made of graphite and has a thickness of T=1.
mm, width W = 10mm, wall thickness in the roll rotation direction is 25mm
And so. The molten metal ejection temperature was set at 1250°C, and the ejection pressure was set at a high level of 1 Kg/cm ² . The angle of the inclined surface of the inner bottom surface of the nozzle was set to α of 80 degrees and α' of 30 degrees. Further, the rear side of the edge of the nozzle opening in the roll rotation direction protruded and extended to the vicinity of the roll surface, and the distance from the roll surface was set to 0.2 mm. As a result, a thin metal plate with a thickness of 0.98 mm and a width of 9.8 mm was cast. We also tried casting a thin metal plate using a ceramic nozzle using stainless steel as the material for the thin metal plate, and were able to cast a thin metal plate with good surface accuracy.

When a thin metal plate is cast using the nozzle of this embodiment as described above, the molten metal flows through the nozzle 1 and the roll 5.
Because it is in contact from all sides, cooling and solidification also proceed from all sides. As a result, a thin metal plate with uniform thickness and width can be manufactured. Note that FIG. 20 shows a cross-sectional view of a thin metal plate cast using the nozzle of this example.

As mentioned above, in the nozzle structure of the fourth embodiment, the molten metal is cooled and solidified early,
When providing forming rolls to improve the surface precision of the thin metal sheet, it is desirable to provide a heater in consideration of the case where the thin metal sheet has already been cooled down too much. FIG. 21 shows a continuous thin metal plate casting apparatus and a forming roll 7 according to a fourth embodiment. The forming roll 7 may not be required depending on the required surface precision of the thin metal sheet, but in the case of a thin metal sheet that requires particularly good surface accuracy, the thin metal sheet may be rolled with a forming roll. This rolling is preferably carried out while the metal sheet is in a hot state in order to reduce the rolling force required for rolling. Therefore, the forming roll 7
should be placed as close to the nozzle 1 as possible. However, this approaching distance has a certain physical limit so that the forming roll 7 does not come into contact with the nozzle 1. Furthermore, as described above, in the nozzle structure of the fourth embodiment, since the molten metal is cooled and solidified early, the thin metal plate 6' may have already been cooled too much by the time of rolling with the forming rolls. . Therefore, as shown in FIG. 22, a heater 10 is provided to prevent the thin metal plate 6' from being cooled.

That is, a forming roll 7 for forming a hot thin metal plate 6' on the surface of the roll 5 is provided at a predetermined distance from the roll 5, and the thin metal plate 6 is placed between the nozzle 1 and the forming roll 7. A heater 10 is provided to prevent the temperature effect of '. This heater 10 may be a burner, for example, or the roll 5
may be heated from below.

Thereby, even if the distance between the nozzle 1 and the forming roll 7 becomes long, the metal thin plate is not cooled, so the forming roll 7 can be set at any position.

In addition, the effect of providing a forming roll is as follows.
In addition to improving the surface precision of the thin metal sheet, since the thin metal sheet undergoes deformation plasticity due to the rolling force, the columnar crystals generated in the thin metal sheet become a destroyed structure, which is advantageous in terms of the strength of the thin metal sheet.

In addition, the gap between the roll 5 and the forming roll 7 should of course be made smaller than the thickness of the thin metal sheet before it is bitten by the forming roll, and if necessary, the thickness of the thin metal sheet should be adjusted. The roll 5 and the forming roll 7 are measured by a sensor and based on the measured thickness.
The gap may be automatically adjusted.

A thin metal plate was cast according to the example shown in FIG. The nozzle shown in Fig. 17 was used, and 50 g of Cu-12% Al alloy was used as the raw material for the metal thin plate. The roll 5 was made of SKD-11 steel with a diameter of 300 mm and the forming roll 7 with a diameter of 120 mm, and the gap between the roll 5 and the forming roll 7 was 0.9 mm. As a result, the thickness is 0.9mm
A thin metal plate with a width of 10.5mm was cast. When a cross section of this thin metal plate in the width direction was polished and the structure was observed under a microscope, it was found that the columnar crystals were destroyed.

The apparatus according to this embodiment may be used in the atmosphere, vacuum, or inert gas. These selections may be made depending on the degree of oxidation of the material of the thin metal plate. Further, the material of the roll 5 and the forming roll 7 may be iron-based, copper-based, ceramic-based, etc., but any material may be used as long as it can withstand rolling force.

〔Effect of the invention〕

According to the present invention, the thickness of the molten metal flow ejected from the nozzle can be made uniform, and a thin metal plate having a uniform thickness can be continuously cast.

[Brief explanation of the drawing]

1 and 2 are schematic side views showing a conventional continuous casting apparatus for metal plates, and FIG. 3 is a longitudinal sectional view of the nozzle used in FIG. 1 or 2.
Fig. 4 is a bottom view of Fig. 3, Fig. 5 is a state diagram of molten metal being ejected from the nozzle of Fig. 3, and Fig. 6 shows the behavior of the ejected molten metal on the roll surface of Fig. 5. 7 and 8 are longitudinal cross-sectional views of the nozzle tested by the present inventor, and FIG. 9 is a longitudinal cross-sectional view of the nozzle according to the first embodiment of the first invention.
Fig. 10 is a side view showing the behavior of the molten metal ejected from the nozzle in Fig. 9 on the roll surface, and Figs. 11 and 12 are longitudinal cross-sectional views of the nozzle showing the second and third embodiments of the present invention. , FIG. 13 is a graph showing the effect of the first embodiment of the present invention, and FIG.
The figure is a graph showing the relationship between the amount of molten metal ejected from a conventional nozzle and the thickness and width of the thin metal plate to be cast. 16 is a cross-sectional view of the ejected molten metal in FIG. 15, FIG. 17 is a perspective view showing the shape of the nozzle in the fourth embodiment of the present invention, and FIG. 19 is a front view of FIG. 17, FIG. 20 is a cross-sectional view of a thin metal plate cast according to FIG. 17, and FIG. 21 is a continuous casting of a metal plate with forming rolls 7. FIG. 22 is a perspective view showing the apparatus, and FIG. 22 is a side view of the continuous thin metal plate casting apparatus showing the entirety of the fourth embodiment. 1... Nozzle, 2... Raw material, 3... Work coil, 4... Molten metal, 5... Roll, 6... Metal plate, 6'... Metal thin plate, 7... Forming roll, 8...
...opening, 9...sleeve, 10...heater, A...
...Pool, C...thick part.

Claims (1)

[Scope of Claims] 1. An apparatus for continuously casting thin metal sheets by spouting molten metal onto the surface of a rotating roll through a nozzle, the nozzle body having an opening at the bottom of the inside thereof; The bottom surface forms an inclined surface toward the opening in the roll rotation direction, and the angle between the front inclined surface in the roll rotation direction and the roll tangent is larger than the angle between the rear inclined surface in the roll rotation direction and the roll tangent. A continuous thin metal plate casting apparatus characterized by the following.