JPS5939223B2 - Composite nozzle for molten metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite nozzle for molten metal in which the inner wall, particularly the outlet inner wall, is made of refractory material and the outer member is made of a heat-resistant material capable of high-frequency induction heating.

A nozzle that supplies a small volume of high-temperature molten metal, for example, when the molten metal temperature is 1200° C. or higher in the direct rolling of iron alloy thin plate tapes, etc. (1) Preheat the nozzle to prevent solidification within the nozzle.

(2) At this time, ensure that the nozzle exit dimensions do not change due to deterioration due to oxidation, etc.

(3) Prevent the nozzle wall from being eroded by the molten metal flow.

etc. are required. However, with conventional nozzle materials, if graphite is used, it is subject to strong oxidation and the outlet size tends to become large, and if alumina is used, it can withstand high temperatures and oxidation, but cannot be subjected to high frequency heating, making it difficult to preheat to high temperatures. , 1200 when stainless steel or heat-resistant steel is used.
All of them are unsuitable because they have the disadvantage of not being able to withstand high temperatures of °C.

In other cases, a quartz glass tube is used as the nozzle material, but this has the disadvantage of poor dimensional accuracy and difficulty in use at high temperatures exceeding 1200°C.

The present invention has been made to address these problems, and includes forming at least the inner wall of the nozzle tip with a ceramic material to prevent changes in the nozzle exit dimension, and wrapping the outside with a material that can be heated by high frequency, such as graphite. This eliminates the above-mentioned drawbacks and makes it possible to easily preheat to a high temperature.

The present invention will be explained below according to embodiments shown in the drawings.

Fig. 1 shows an example of manufacturing a tape-shaped metal product by direct rolling, in which a molten metal 3 is heated and held in a melting crucible 2 equipped with a high-frequency induction coil 1 on the outside, and a nozzle 4 is connected to the bottom of the crucible 2. The molten metal flow 6 is formed at the joint or adjacent part of the metal rolls 5, 5 which are joined or rotated close to each other or in the vicinity thereof.
is supplied, cooled and rolled between rolls 5, and a product tape 7 is obtained.

In this case, the amount of molten metal flow 6 is usually small and the temperature is high.
When making iron-based alloys, the amount is less than 2.5 kg, but the temperature exceeds 1200°C.

Therefore, normal metal materials cannot be used for the nozzle 4.

In addition, it is necessary to preheat the nozzle to a considerably high temperature to prevent not only the internal part from being exposed to high-temperature fluid but also to prevent solidification within the nozzle. Composite materials are the best choice, but they are extremely expensive and extremely difficult to process.

Therefore, in the present invention, the nozzle 4 is arranged as shown in FIG.

As shown in the figure, the inner wall 8, especially its tip, is made of ceramics to prevent erosion by the high-temperature fluid of the molten metal flow 6, and the outer material 9 forming the outer periphery is made of a material capable of being heated by cylinder frequency induction, such as graphite. I try to preheat to a high temperature.

It is economically advantageous that the ceramic forming the inner wall 8 is easily machined, such as boron nitride, and is fitted into a plate shape to avoid cutting out a complicated shape.

It is desirable to thermally spray ceramics such as alumina or zircon on the inner wall portion not covered by the flat plate to form the thermally sprayed inner wall 10 as shown in FIG. 2A.

If preheating to 1000° C. or less is sufficient, it is also possible to use a structure in which the outer member 9 is made of stainless steel or heat-resistant steel and the inner wall 8 is made of a material sprayed with ceramics such as alumina or zircon.

Also, when making molten metal with a relatively low melting point by the roll quenching method or the centrifugal quenching method, it is necessary to jet the molten metal from a nozzle. Requires flow nozzle.

In this case, if both the production volume and the tape width are small, it is possible to use a quartz glass tube with holes as a substitute for the nozzle, but quartz glass is easily eroded, and it is difficult to make a flat nozzle. This is almost impossible, which is why the nozzle of the present invention as shown in FIG. 2 is extremely effective.

As described above, the present invention provides a nozzle that is capable of high-frequency induction heating, has excellent corrosion resistance, particularly heat-resistant fluid, and oxidation resistance, and is highly accurate and inexpensive, and has great industrial value.

Examples of the present invention are shown below.

Example 1 In direct rolling of an 84%Fe-10%Si-6%A7 alloy, a plate having a width of 20 mm and a thickness of 0.3 mm was manufactured using the nozzle 4 as shown in FIG. 2 and according to the method shown in FIG. 1.

The nozzle had an inner wall made of boron nitride with a thickness of 2 mm, and the other inner walls were made of graphite sprayed with alumina, and was preheated to 1200° C. in an argon atmosphere.

The above product was produced by casting the raw material No. 7301 into a 100φ roll bite at about 1 m/sec, and rotating the roll at about 300 rpm.

This resulted in approximately 16 m of tape-shaped metal.

The boron nitride on the inner wall plate of the upper two nozzles did not change even after repeating direct rolling about 20 times under the same conditions and showed sufficient durability.

Example 2 The nozzle was made of stainless steel equivalent to SUS310S and had an alumina coating applied to the inside of the nozzle body by thermal spraying to form an alumina film of approximately 0.1 mm over the entire inner wall, and the other procedures were the same as in Example 1. .

The preheating temperature was approximately 800°C.

A product with a length of about 13 m was obtained from the 600 V raw material, but no peeling of the alumina film was observed during three consecutive castings.

[Brief explanation of drawings]

FIG. 1 is an illustration of direct rolling to which the nozzle of the present invention is applied;
FIG. 2A is a vertical cross-sectional view and a cross-sectional view showing an embodiment of the nozzle of the present invention. 1... High frequency induction coil, 4... Nozzle, 8... Nozzle inner wall plate, 9... Nozzle external material, 10... Nozzle inner wall thermal spray material.

Claims (1)

[Claims] 1. Ceramics or other corrosion-resistant and oxidation-resistant refractories are fitted or pasted on the inner wall of the tip outlet at least by thermal spraying, and the outer member is made of graphite or other heat-resistant material that can be heated by high-frequency induction heating. Composite nozzle for molten metal