JPH08238541A - Method of making supplying quantity definite of molten metal and alloy to cooling base board - Google Patents

Abstract

PURPOSE: To produce high quality thin strip having high thickness precision by supplying molten metal from a tundish to cooling base while making height of molten metal constant. CONSTITUTION: By releasing a tundish stopper 4, a molten metal 3 in a tundish 2 is injected on a cooling roll 6 rotating in high speed through a molten metal flow path 11, a thin strip 7 is produced. A dummy volume 1 is immersed in the molten metal 3 in tundish 2, corresponding to variation in the height (h) of molten metal surface in the tundish in casting, by moving the dummy volume 1 up/down, the height (h) of molten metal surface is kept constant and the molten metal 3 is supplied on the cooling roll 6. By this method, a quantity of molten metal supplied to the cooling roll is made constant, an uniform thickness then strip is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire and a thin strip metal and alloy (hereinafter simply referred to as thin ribbon) by rapidly solidifying molten metal and alloy (hereinafter simply referred to as molten metal) on a moving cooling substrate. The method of supplying molten metal to a cooling substrate in a liquid quenching method for obtaining

[0002]

2. Description of the Related Art As a liquid quenching method for producing a ribbon, for example, a so-called single roll method in which a molten metal is supplied onto one cooling roll which is rotating at a high speed to obtain a ribbon,
There is a twin roll method in which molten metal is supplied between a pair of high speed rotating cooling rolls to obtain a ribbon.

A method of forming a ribbon by the liquid quenching method will be described by taking as an example a case where a single roll rapid solidification ribbon production apparatus shown in FIG. 2 is used. In FIG. 2, the molten metal 3 is supplied to the tundish 2. A tuyere brick 8 is provided on the bottom wall of the tundish 2, and an intermediate nozzle 9 and a nozzle holder 10 are connected to the tuyere brick 8. Holes are provided in the tuyere brick 8, the intermediate nozzle 9, and the nozzle holder 10, and these holes are connected to each other to form the molten metal flow path 11 and the enlarged internal space 14 in the nozzle holder 10.

Further, a nozzle tip 12 is attached to the tip of the nozzle holder 10, and a nozzle slit 13 provided inside the nozzle tip 12 has a molten metal flow path 11.
Is in communication with. The enlarged internal space 14 in the nozzle holder 10, the nozzle tip 12, and the nozzle slit 1
3 is shown in FIG. 3, the enlarged internal space 14 refers to a portion where the molten metal flow passage 11 is widened in the nozzle holder 10 in order to obtain a wide ribbon, and the nozzle slit 13 is
It refers to an opening provided in the nozzle tip 12 for ejecting molten metal.

By raising the tundish stopper 4, the molten metal 3 in the tundish 2 flows out from the nozzle slit 13 toward the cooling roll 6 via the molten metal flow path 11. At this time, the flow rate of the molten metal 3 flowing out from the nozzle slit 13 toward the cooling roll is controlled according to the molten metal static pressure in the tundish 2. The molten metal 3 flowing out from the nozzle slit 13 is rapidly cooled on the surface of the cooling roll 6 and becomes a ribbon 7. In order to facilitate understanding of the entire device in FIG.
The cooling roll 6 is drawn at a scale larger than that of the tundish 2.

In any of the methods, the strip thickness obtained by the liquid quenching method is as small as less than 1 mm,
The cooling rate is 10 ² K / sec or more. In the single roll method, the plate thickness has such a limitation in order to obtain a good ribbon in principle. On the other hand, in the twin roll method,
Although it is not impossible to manufacture a ribbon having a plate thickness of 1 mm or more by controlling a manufacturing factor, the liquid quenching method targeted by the present invention does not simply manufacture a thin material,
When the purpose is to improve various properties by rapid solidification, that is, when the cooling rate is 10 ² K / sec or more, when using the plate thickness, it is limited to the case where a thin strip having a plate thickness of less than 1 mm is manufactured. .

Due to such restrictions, for example, in the case of the liquid quenching method which is the object of the present invention, compared with the conventional solidification method such as the ordinary ingot casting method and the continuous casting method, the supply of the molten metal to the cooling substrate is performed. There is a big difference in quantity. That is, for example,
In the case of a continuous casting method such as steel that is generally adopted, the amount of molten metal that can be supplied to a mold is, for example, in the case of steel, on the order of several tons / minute, and in the ordinary ingot-making method, it is more than that. Is also possible.

On the other hand, in the liquid quenching method of the present invention, the supply amount must be considerably reduced to the order of 10 kg / min. For example, the strip thickness normally produced by the single roll method is 0.1 mm. In this case, the peripheral speed of the chill roll is about 5 m / sec, and the strip width is 200 mm at most. Therefore, for example, if iron is the main component, the supply amount of the molten metal is controlled to about 50 kg / min. Must.

On the other hand, not only in the case of the liquid quenching method, but in any manufacturing process, the product to be manufactured is required to have a uniform plate thickness. Especially, in the case of the liquid quenching method, Secondary processing such as rolling is difficult because it is an already thin product, and problems with mechanical properties make it difficult to make the plate thickness uniform after casting. Therefore, in the production by the liquid quenching method, there has been a strong demand for a thin strip having a uniform plate thickness.

[0010]

In order to make the strip thickness uniform, it is necessary to make the amount of molten metal ejected from the nozzle onto the cooling substrate constant. As described above, in the liquid quenching method, the amount of molten metal supplied to the cooling substrate is 10
Since the quantity is as small as kg / minute, in the liquid quenching method, even a slight change in the supply amount had a great effect on the product thickness. In the liquid quenching method, the molten metal is supplied onto the cooling substrate through the tundish as described above. During the casting, the amount of the molten metal supplied is mainly the level of the molten metal in the tundish. (Hereinafter, simply referred to as the level of the molten metal).

Therefore, the fluctuation of the molten metal height causes the fluctuation of the supply amount of the molten metal to the cooling substrate, which leads to the fluctuation of the strip thickness. The cause of the melt level is due to fluctuations in the supply to the tundish, etc., but it is very difficult to suppress fluctuations in the supply to the tundish, and fluctuations in the melt level are unavoidable and more uniform. It has been difficult to manufacture a ribbon having a uniform plate thickness.

An object of the present invention is to suppress fluctuations in the level of the molten metal of a container which receives a molten metal such as a tundish and induces the molten metal on a cooling substrate in a liquid quenching method,
It is an object of the present invention to provide a method for stabilizing the amount of molten metal supplied to a cooling substrate.

[0013]

SUMMARY OF THE INVENTION The present invention has the following structures. A method of supplying molten metal and alloy to a cooling substrate when producing metal and alloy in the form of lines and thin strips by a liquid quenching method in which the molten metal and alloy are rapidly solidified on a cooling substrate moving at high speed. A container for receiving the metals and alloys and for guiding the molten metals and alloys to the cooling substrate is inserted into a dummy volume that can be moved up and down so as to be immersed in the molten metals and alloys. The molten metal and alloy are supplied from the container to the cooling substrate while the level of the molten metal and alloy in the container is kept constant by raising and lowering the dummy volume according to the fluctuation of the amount of metal and alloy. Is a method for stabilizing the supply amount of the molten metal and alloy to the cooling substrate.

[0014]

The method of the present invention will be described below with reference to the schematic diagram shown in FIG. As shown in FIG. 1, according to the method of the present invention, the tundish stopper 4 is released and the molten metal 3 in the tundish 2 is formed by connecting the tuyere brick 8, the intermediate nozzle 9 and the hole of the nozzle holder 10. In the method of manufacturing the ribbon 7 by jetting it onto the cooling roll 6 which is rotating at a high speed through the molten metal flow path 11, the dummy volume 1 is immersed in the molten metal 3 in the tundish 2 and The dummy volume 1 is moved up and down in accordance with the variation of the level of the molten metal in the tundish 2 (the height indicated by h in FIG. 1) to keep the molten metal 3 at a constant level and the molten metal 3 is cooled. It is a method of supplying to No. 6.

According to this method, the amount of the molten metal 3 supplied to the cooling roll 6 can be made constant, so that a ribbon having a uniform plate thickness can be obtained. The molten metal 3 is supplied to the tundish 2 from a container such as a ladle that holds the molten metal 3 as described in, for example, Japanese Patent Laid-Open No. Sho 5 (1998).
According to the siphon method described in Japanese Patent Publication No. 9-042161, a small flow rate is controlled in advance to an order of 10 kg / min.
For example, as shown in FIG. 1, it is done through a long nozzle 5. The fluctuation of the molten metal surface height during casting mainly occurs due to the fluctuation of the amount of the molten metal 3 supplied to the tundish 2.

The method of vertically moving the dummy volume 1 will be specifically described. For example, if the level of the molten metal becomes lower than a predetermined value due to fluctuations in the supply amount of the molten metal 3 to the tundish 2, etc. Volume 1 is lowered to raise the height of the molten metal so that the height of the molten metal reaches a predetermined value. When the height of the molten metal becomes higher than a predetermined value, the dummy volume 1 is raised to lower the height of the molten metal so that the height of the molten metal becomes a predetermined value.

The vertical movement of the dummy volume 1 depending on the fluctuation of the level of the molten metal is, for example, the level of the molten metal is accurately detected by various sensors, and this measurement signal is transmitted to the arithmetic controller to perform the calculation. The controller calculates the amount by which the dummy volume 1 should be moved up and down based on the measurement signal and feeds back the calculation result to the control system of the dummy volume 1. A preferred value of the level of molten metal and a method of detecting the level of molten metal will be specifically described in Examples.

In the method of the present invention, the positional relationship between the tundish and the cooling roll is not particularly limited. That is, although the case where the tundish is placed laterally with respect to the cooling roll has been described, the position of the tundish may be directly above the cooling roll or at an oblique position. However, even if the position of the tundish changes, it is necessary to change the positions of the tuyeres of the tundish, the intermediate nozzle, the nozzle holder, etc. according to the position of the tundish so that the nozzle slit faces the surface of the cooling roll. .

Further, preferred dimensions and materials of the dummy volume used in the method of the present invention will be described in Examples, but when used, in order to prevent damage to the dummy volume and temperature drop of the molten metal as much as possible, Before supplying the molten metal, it is necessary to sufficiently preheat it by a method using a burner or electric heating.

The metal applicable to the method of the present invention is particularly advantageous in the case of an alloy which is likely to become amorphous and a metal and an alloy which are difficult to process such as rolling, but are not limited thereto. It is applicable to the production of ribbons from various molten metals.

Further, the basic manufacturing apparatus adopted in the method of the present invention is, as described above, a method of jetting a molten metal onto a cooling substrate through a nozzle and quenching and solidifying the molten metal by thermal contact so that the liquid is rapidly cooled. Among the devices, there are so-called single roll device and twin roll device. The single roll device includes a centrifugal quenching device that uses the inner wall of the drum, a device that uses an endless type belt, and improved versions of these, such as auxiliary rolls,
It also includes a roll surface temperature controller attached, or casting under reduced pressure or in a vacuum or in an inert gas.

Next, the casting conditions adopted in the method of the present invention and the concrete casting work will be described. The injection pressure of the molten metal is 0.01 to 3 kg / cm ² , and is mainly controlled by using the height of the molten metal in the tundish. The rotation speed (surface speed) of the cooling roll is in the range of 5 to 60 m / sec. Optimum values are selected for these conditions in accordance with the target strip thickness and other manufacturing conditions.

[0023]

EXAMPLES Using the single roll spinning apparatus as shown in FIG. _{2, Fe-B 12 -Si 6.5} -C 1 ( atomic%) was produced alloy ribbons. For melting the alloy, a ladle equipped with a high frequency induction device was used. A dummy volume as shown in FIG. 1 was attached to the tundish. This dummy volume is made of alumina-carbon and has BN on the outside.
Applied about mm. An electric heating device was attached inside so that preheating could be performed. Also, it can be moved up and down by connecting to a hydraulic cylinder via a control panel. The dummy volume had outer dimensions of 180 mm in length and width and 200 mm in height.

At the same time when the melting of the alloy in the ladle is started,
The dummy volume and tundish were preheated. The dummy volume was preheated by a pre-equipped electric heating device, and the tundish was preheated by using a gas burner. After the alloy had melted, these preheats were stopped and the molten alloy was fed into the tundish.

When the height of the molten alloy in the tundish reached 250 mm, the tundish stopper was released and the molten alloy was jetted onto a rotating cooling roll. The height of the molten metal in the tundish is detected by a pre-mounted borescope, this measurement signal is transmitted to the arithmetic controller, and the amount of stroke above and below the dummy volume is calculated.
The result was fed back to the control panel of the dummy volume, and the dummy volume was moved up and down to keep the height of the molten metal constant.

The other manufacturing conditions were as follows. Molten alloy temperature in the ladle at the time of pouring: 1350 ° C Nozzle opening shape: Two 120 mm x 0.7 mm rectangular slits arranged at 1.5 mm intervals Roll surface speed: 20 m / s Nozzle gap: 0.3 mm Preheating temperature of dummy volume: 1200 ℃

As a result, the fluctuation of the molten metal surface height of the tundish detected by the borescope was within the range of ± 6 mm. As a result of casting, a thin strip having a width of about 120 mm and a good appearance was obtained. From the obtained ribbon, samples each having a length of 20 mm were taken at positions where the intervals were constant in the longitudinal direction, and their plate thicknesses were measured. The thickness of the strip was calculated from the weight of the strip, the length and width of the strip, and the density of the alloy (7.26 g / cm ³ ). As a result, the average plate thickness of the samples was 52 μm, and the plate thicknesses of all the samples were within the range of ± 3 μm.

From the above results, it was found that by using the dummy volume for the tundish, a ribbon having a considerably high plate thickness accuracy can be obtained. It is judged that this is because the fluctuation of the level of the molten metal in the tundish was suppressed by using the dummy volume.

Comparative Example Fe—B ₁₂ —Si _6.5 —C ₁ (atomic%) alloy ribbon was manufactured using a single roll ribbon manufacturing apparatus as shown in FIG. However, casting was performed without inserting anything into the tundish. The other casting conditions were the same as in the example.

As a result, the variation in the height of the molten metal surface of the tundish during casting detected by the borescope was as large as ± 17 mm. As a result of casting, a ribbon having a width of about 120 mm was obtained. Samples each having a length of 20 mm were sampled from the obtained ribbon at positions with even intervals in the longitudinal direction, and their plate thicknesses were measured. As a result, the average plate thickness of the sample was 51 μm, and the plate thickness variation was as large as ± 10 μm. From the above results, it was judged that the tundish was cast without using a dummy volume, so that it was not possible to suppress the fluctuation of the molten metal surface height in the tundish, and it became a thin strip with a large plate thickness fluctuation. .

[0031]

As described above, according to the present invention, it is possible to manufacture a high-quality ribbon with high plate thickness accuracy in the liquid quenching method. In addition, the production yield was improved because the amount of scrap produced due to defective plate thickness was reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a method of the present invention.

FIG. 2 is a schematic diagram for explaining a state of casting using a single roll rapid solidification ribbon production apparatus.

FIG. 3 is an enlarged schematic diagram for explaining a state of casting using a single roll rapid solidification ribbon production apparatus.

[Explanation of symbols]

 1 Dummy Volume 2 Tundish 3 Molten Metal 4 Tundish Stopper 5 Long Nozzle 6 Cooling Roll 7 Thin Strip 8 Tuyere Brick 9 Intermediate Nozzle 10 Nozzle Holder 11 Molten Metal Flow Path 12 Nozzle Tip 13 Nozzle Slit 14 Expanded Internal Space

Claims (1)

[Claims] 1. A method of supplying a molten metal and an alloy to a cooling substrate when producing a wire and a thin strip of the metal and the alloy by a liquid quenching method in which the molten metal and the alloy are rapidly solidified on a cooling substrate moving at a high speed. In the method, a container for receiving the molten metal and the alloy and for guiding the molten metal and the alloy to the cooling substrate is inserted into the molten metal and the alloy, and a dummy volume that can be moved up and down is inserted,
Depending on the variation in the amount of molten metal and alloy received by the container, the dummy volume is moved up and down to keep the molten metal and alloy in the container at a constant molten metal level, and from the container to the cooling substrate. A method for stabilizing the supply amount of molten metal and alloy to a cooling substrate, which comprises supplying molten metal and alloy.