JPS5942165A - Preheating method of slit nozzle for producing amorphous alloy light-gauge strip - Google Patents

Abstract

PURPOSE:To suppress the deformation owing to the thermal strain of a nozzle tip and to obtain an amorphous alloy light-gauge strip having good surface characteristics by controlling adequately the preheating temp. of the tip type slit nozzle in conformity with the temp. of the molten metal in a tundish. CONSTITUTION:A tip type slit nozzle 3 is mounted to a nozzle tip holder 2 communicated and installed in the lower part of a tundish 1, and the nozzle tip 3 is electrically preheated. A thermocouple 4 or the like is inserted in the drilled part of the holder 2 at both transverse ends of the tip 3 to measure the preheating temp. The preheating temp. is controlled to the temp. of the molten metal in the tundish 1+ or -150 deg.C to prevent the deformation owing to the thermal strain of the tip 3. An amorphous alloy light-gauge strip having no defects in the central part is produced by the above-mentioned preheating method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preheating a nozzle for producing an amorphous alloy ribbon.

Amorphous alloy thin? A liquid quenching method is being researched as a method for producing tF. In particular, the single roll method is considered to be suitable for mass production. This method is characterized by rapidly cooling the molten metal by pouring it through a narrow slit of about 1 inch or less onto a cooling surface that is moving at high speed. Generally, high-temperature liquids tend to solidify and are difficult to handle, but in this case in particular, the temperature is relatively close to the melting point of the molten metal and the slit is very narrow, which makes it even more likely to clog, making it difficult to start pouring the liquid stably.

Establishing a method for sufficiently preheating the nozzle tip is an important development issue on an industrial production scale.

By the way, certain amorphous alloys have very good electromagnetic properties, so they are highly expected to be used as cores of power transformers, and there is a method to mass-produce thin strips with a width of more than 150 mm at a low cost. is being actively researched.

According to the research conducted by the present inventors, it has become clear that in the mass production method of such wide materials, it is insufficient to simply eliminate clogging of the slits at the initial stage of pouring.

In order to mass-produce thin strips with good shape and surface properties at low cost, it is necessary to use expensive so-called new ceramics or fine ceramics as the material for the slit nozzle. In order to increase equipment operation rate and reduce manufacturing costs, we designed a crucible that is separate from the melting furnace (hereinafter referred to as Tandigy) to be equipped with the smallest possible ceramic nozzle part (hereinafter referred to as nozzle tip). is one of the promising directions for continuous mass production.

The smaller the nozzle tip is, the less likely it is to crack due to thermal shock and the easier it is to use, but on the other hand, it is easily deformed due to uneven temperature distribution. The biggest problem in researching a continuous mass production method using a tip-type nozzle attached to a Tandigy is that even if production starts successfully, the middle part of the wide material becomes extremely thin, and in some cases, the center part of the wide material becomes extremely thin. It's about leaving a hole.

As a result of detailed research, it was found that the cause was the difference between the operating temperature of the slit and the preheating temperature. Theoretically, the slit itself deforms due to thermal strain caused by the temperature of the working surface of the slit being different from the temperature of other parts (which have reached the preheating temperature), resulting in a multi-polar structure with a narrow center. The case turned out to be blocked. Target thickness of ribbon: 30μm
It has been found that in order to achieve a plate thickness tolerance of ±10%, it is sufficient to preheat the entire internal pressure nozzle tip to an operating temperature of 150°C during pouring, preferably to ±50°C.

The gist of the present invention is to set the preheating temperature of the tip-type slit nozzle 3 attached to the nozzle tip holder 2 connected to the tundish 1 installed separately from the melting furnace to within the tundish 1, +7)? 8 Hot water temperature ±150℃
The present invention provides a method for preheating a slit nozzle for producing an amorphous alloy ribbon, which is characterized by controlling

The present invention will be explained in detail below based on the drawings.

FIG. 1 is a partially sectional front view showing an embodiment of the present invention, and FIG. 2 is a side view. In the figure, a nozzle tip holder 2 is installed in communication with the lower part of a tank 1 that is supplied with hot water from a melting furnace (not shown), and a tip type slit is installed at the bottom of the holder 2 near a cooling roll (not shown). A nozzle 3 is attached, and thermocouples 4, 4 are inserted into the drill hole of the nozzle tip holder 2 at both ends of the nozzle tip 3 in the middle direction (FIG. 1) to measure the preheating temperature. has been done.

The nozzle tip 3 is preheated by heating with electricity, and at this time, the preheating temperature is controlled to a temperature range in which the nozzle tip 3 is hardly subjected to thermal strain deformation with respect to a predetermined molten metal temperature in the tundish 1. .

When manufacturing an amorphous alloy ribbon as in the present invention, the temperature of the molten metal is approximately 1200 to 1400°C, so if the preheating temperature is within ±150°C of these temperatures, thermal distortion of the nozzle tip will occur. Deformation is within an acceptable range.

That is, if the preheating temperature of the nozzle tip 3 is lower than the molten metal temperature -150°C, the central portion of the slit will be closed within a few seconds after pouring the molten metal. On the other hand, if the molten metal temperature exceeds +150°C, the nozzle holder will be overheated, and particles will often fly off before the ribbon comes out at the start of pouring.

Example: Drill a hole in a graphite nozzle tip holder, bring two CA thermocouples into contact with both ends of a BN nozzle tip,
The nozzle tip is heated with electricity and the preheating temperature is monitored.
When the temperature reached 1250℃, Fe -B- at 1350℃
Pouring of the 8i-C series molten metal was started by supplying it from the ladle to the tandigy, and a thin strip was manufactured. The cooling roll is a 1,000φ x 300W water-cooled steel alloy roll with a circumferential speed of 25m/8eC1 slit of 0.6+nm x 150m.
m, the gap between the roll nozzles was 0.2 van %, and the molten metal head was 300-. A total of 50 mm was poured, but the board thickness was within 25 μm±2 μm, and there were no defects in the center.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG.

Claims (1)

[Claims] The preheating temperature of the 1'C Tizzo type slit nozzle 3 is set to the nozzle tip holder 2 installed in connection with the tongue holder 1 which is installed separately from the stone cracking furnace.
Control the temperature of the bath water within ±150℃'? r,IF,
A method for preheating a slit nozzle for producing an amorphous alloy ribbon with +j characteristics.