JPH08281389A - Production of rapidly solidified thin strip - Google Patents

Abstract

PURPOSE: To surely catch the tip part of a thin strip at the time of starting coiling of the thin strip and to stably coil the thin strip by adjusting a spouting pressure to be lower than a prescribed value only at the time of starting casting and thereafter, continuing the casting immediately at the prescribed spouting pressure. CONSTITUTION: The spouting pressure is made low by lowering the molten metal surface height lower than a prescribed height only at the time of starting the casting, and thereafter, the casting is immediately continued by making the molten metal surface height the prescribed height. Then, the control of the molten metal height can be executed by e.g. controlling the molten metal 1 quantity supplied to a tundish 2 through a long nozzle 4. At the time of starting the casting, the supplied quantity of the molten metal 1 onto a cooling roll 9 can be restrained by making the spouting pressure a low pressure, and the tip part of the strip is easily caught with a coiling roll. That is, at the time of starting the casting, heat dissipation in the cooling roll 9 is insufficient, but the supplying quantity of molten metal to the cooling roll 9 is reduced by restraining the spouting pressure, thereby a thickness of the cast strip is made to be thin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention rapidly solidifies liquid metals and alloys (hereinafter simply referred to as "molten metal") on a moving cooling substrate to form thin strips of metals and alloys (hereinafter simply referred to as "metals"). Referred to as "thin band").

[0002]

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

A method of forming a ribbon by the liquid quenching method will be described, for example, using a single roll rapid solidification ribbon production apparatus shown in FIG. In FIG. 3, the molten metal 1 is supplied to the tundish 2 so that the level of the molten metal is constant. A tuyere brick 5 is provided on the bottom wall of the tundish 2, and an intermediate nozzle 6 and a nozzle holder 7 are connected to the tuyere brick 5. Holes are provided in the tuyere brick 5, the intermediate nozzle 6, and the nozzle holder 7, and these holes are connected to form the molten metal flow path 8 and the enlarged internal space 15 in the nozzle holder 7. A nozzle tip 14 is attached to the tip of the nozzle holder 7, and a nozzle slit 16 provided inside the nozzle tip 14 has a molten metal flow path 8
Is in communication with. The enlarged internal space 15 in the nozzle holder 7, the nozzle tip 14, and the nozzle slit 16
4, the enlarged internal space 15 refers to a portion where the molten metal flow path 8 is widened in the nozzle holder 7 in order to obtain a wide ribbon, and the nozzle slit 16 is provided in the nozzle tip 14. It refers to the opening for spouting molten metal.

By raising the tundish stopper 3, the molten metal 1 in the tundish 2 passes from the nozzle slit 16 through the molten metal flow path 8 to the cooling roll 9.
Spill towards. At this time, depending on the static pressure of the molten metal in the tundish 2, the nozzle slit 16 causes the cooling roll 9 to
The flow rate of the molten metal 1 flowing out toward is controlled. The molten metal 1 flowing out from the nozzle slit 16 is rapidly cooled on the surface of the cooling roll 9 to become the ribbon 10. In FIG. 3, in order to facilitate understanding of the entire device,
The cooling roll 9 is drawn at a scale larger than that of the tundish 2.

Various methods have been proposed so far for winding the thin strip obtained by the liquid quenching method online immediately after casting. Basically, a winding roll is used, and a method of winding by rotating the winding roll is adopted, but in any method, at the start of winding, that is, how the thin strip is wound on the winding roll. The point is to let them be caught. Among them, when the ribbon has magnetism, for example, using a winding roll having a permanent magnet embedded in the surface, the ribbon is caught by the force of the magnet, and then a method of winding by rotation of the winding roll, For example, it is proposed in Japanese Patent Laid-Open No. 57-94453.

According to this winding method, after rapid solidification on a rotating cooling substrate, a thin ribbon having magnetism that rotates while adhering to the surface of the cooling substrate is peeled off by a jet of a sharp high-pressure gas, and at the same time, the thin film after peeling is removed. In this method, the tip of the strip is magnetically attracted to a winding roll having a magnetic property on the surface that rotates at a peripheral speed equal to or higher than that of the rotary cooling substrate, and then the strip is continuously wound. Further, the publication discloses that a roll having a permanent magnet such as a rare earth cobalt magnet embedded in its surface can be used as a winding roll. The present inventors attempted to wind the ribbon by this method in order to wind the obtained ribbon online when producing the ribbon having magnetism, for example, in the single roll method.

[0007]

As a result, although the ribbon formed on the roll could be peeled off by the jet of high-pressure gas, the success rate of capturing the tip of the ribbon by the take-up roll was about 30%. If it fails to capture the tip, the ribbon production had to be stopped. Thus, failure to capture the leading edge of the ribbon leads to a reduction in the yield of ribbon production, which is not preferable.

The inventors of the present invention are required to control the jet pressure at the start of casting in order to stably capture the tip of the ribbon by the conventional method using a winding roll having a permanent magnet embedded on the surface. By finding out that there is something and performing an experiment under various conditions, the conditions under which the tip of the ribbon can be stably captured are understood, and the present invention has been completed.

The present invention eliminates the conventional trouble that has occurred at the time of capturing the front end of the ribbon in the conventional method using a winding roll having a permanent magnet embedded on the surface thereof, and winds the ribbon with a high success rate. The purpose is to provide a way to take.

[0010]

SUMMARY OF THE INVENTION The present invention has the following structures. That is, in a method for producing a rapidly solidified ribbon by ejecting liquid metal and alloy onto a moving cooling substrate, the ejection pressure is made smaller than a predetermined value only at the start of casting, and immediately thereafter, a predetermined ejection pressure A method for producing a rapidly solidified ribbon, characterized by continuing casting.

The present invention will be described in detail below. The jet pressure referred to in the present invention is the pressure applied to the molten metal in order to supply the molten metal to the surface of the cooling roll. Although there are various methods for applying the jet pressure to the molten metal, the present invention will be described by taking the case of using the static pressure of the molten metal 1 as shown in FIG. 1 as an example.

FIG. 1 shows a molten metal 1 in a tundish 2.
Of the molten metal 1 is sprayed onto the surface of the cooling roll 9 by using the static pressure of the molten metal 1 in the tundish 2 to form a ribbon. Here, the static pressure of the molten metal 1 corresponding to the jet pressure is the molten metal level of the molten metal 1 in the tundish 2 shown by h in FIG. 1 (hereinafter, simply referred to as “molten metal level”). It is decided and the control of the ejection pressure at the time of casting is performed by the height of the molten metal surface. The present invention is a method for reducing the ejection pressure by lowering the molten metal surface height below a predetermined height only at the start of casting, and immediately after that, continuing the casting with the molten metal surface height at a predetermined value. The molten metal height can be controlled by controlling the amount of the molten metal 1 supplied to the tundish 2 via the long nozzle 4, for example.

By reducing the jet pressure at the start of casting, the amount of molten metal supplied to the cooling roll at the start of casting can be suppressed, and the ribbon end can be easily captured by the winding roll. It is considered that the reason why the tip of the ribbon can be easily captured by reducing the ejection pressure is that problems such as insufficient heat removal from the cooling roll and defective casting can be solved.
In other words, although heat is not sufficiently removed from the cooling roll at the start of elimination casting, the amount of molten metal supplied to the cooling roll is reduced by suppressing the jet pressure, and the strip thickness is reduced.
If the thickness of the ribbon becomes small, even if the heat removal by the cooling roll is insufficient, the ribbon can be cooled to the extent that it is below the Curie point. When using the attractive force of a magnet to wind a ribbon, it is assumed that at least the part of the ribbon that is trapped has magnetism, but even a ribbon that is magnetic at room temperature does not exhibit ferromagnetism above the Curie point. Therefore, in order to wind the ribbon using the attractive force of the magnet, at least the tip of the ribbon to be captured by the take-up roll needs to be below the Curie point. However, since the plate thickness of the ribbon becomes smaller than the predetermined value by making the ejection pressure smaller than the predetermined value, the ejection pressure needs to be set to the predetermined value as soon as possible. That is, it is necessary to make the molten metal height smaller than a predetermined value only at the start of casting and immediately thereafter to a predetermined value.

In the present invention, the preferable range of the height of the molten metal at the start of casting is not particularly limited, but it is preferably 1/2 or less, more preferably 1/3 or less of the predetermined molten metal height. Of course, the larger the predetermined value, the smaller the ratio of the molten metal height at the start of casting to the prescribed molten metal height.

Further, in principle, it is preferable that the timing for setting the molten metal surface height to a predetermined value is immediately after the take-up roll has captured the front end of the ribbon. If the timing of setting the molten metal surface height to a predetermined value is delayed after capturing the tip, there will be many parts thinner than the target plate thickness in the obtained ribbon and the manufacturing yield will be deteriorated. Is not preferable. In addition, preferable conditions regarding the molten metal height at the start of casting and the timing of setting the molten metal height to a predetermined value will be described in detail in Examples.

In the liquid quenching method, as a method for applying a jet pressure to the molten metal, in addition to the method of using the static pressure of the molten metal described above, for example, a container holding the molten metal is hermetically sealed, and a gas is stored in the container. There is also a method of increasing the pressure in the feeding container, but in the present invention, the method of applying the jet pressure to the molten metal is not limited to these methods.

As a condition for winding the ribbon in the present invention, the distance between the winding roll and the cooling roll at the time of capturing the leading end of the ribbon should be as close as possible without colliding, and for example, about 10 mm or less is preferable. . However, if you can capture the tip of the ribbon and wind it stably,
It is necessary to keep the take-up roll away from the cooling roll in consideration of the take-up thickness of the take-up roll. The timing and other conditions for moving the take-up roll away will be described in detail in Examples.

In order to mass-produce thin strips using the method of the present invention, when a disk 12 is rotated as shown in FIG. 2 and cannot be wound up by one take-up reel 11. In consideration of the above, a system in which the spare take-up reel 11 ′ is on standby on the cooling roll 9 side can also be adopted. When the thin ribbon 10 forms a long pass line as described above, the use of the support roller 13 enables stable winding.

The winding roll which can be used in the method of the present invention is a roll in which a rare earth cobalt magnet or a permanent magnet such as samarium-cobalt is embedded so as to be exposed on the surface. In addition, a roll whose surface is magnetized by an electromagnet method may be used.

The case of the single roll method has been described above as the method of forming the ribbon. In the method of the present invention, for example, a pair of high speed rotating cooling substrates (hereinafter referred to as cooling rolls) is used. It can also be applied to other liquid quenching methods such as a twin roll method in which molten metal is supplied to obtain a ribbon. The preferred casting conditions for forming the ribbon will be described in detail in Examples.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. EXAMPLE 1 _{Fe-Si 6.5 -B 12 -C 1} ( atomic%) by using a single roll spinning apparatus in the atmosphere shown in Fig. 1 to produce a ribbon of an amorphous alloy, the thin films by a take-up roll winding I tried to get it. The nozzle opening shape of the molten alloy jet nozzle tip used for casting was a rectangular shape of 1 mm × 150 mm. Further, the flow rate of the molten sample of the above alloy melted by the high frequency induction method was set to 50 kg / min, and it was sprayed on the peripheral surface of the cooling roll made of copper to form a ribbon. The surface speed of the cooling roll was 24 m / sec.

The jet pressure was controlled by the height of the tundish surface, but the height of the surface of the molten metal at the start of casting was 130 mm, and after the start of casting, that is, after releasing the tundish stopper,
Immediately after 4 seconds, the amount of molten alloy supplied to the tundish was increased so that the height of the molten metal surface became 270 mm.
After that, the supply amount of the molten alloy to the tundish was controlled so that the height of the molten metal surface was maintained at 270 mm.

As a take-up roll, φ10 mm × 6 on the surface
Round bar-shaped samarium-cobalt of mmt embedded with different magnetic poles adjacent to each other, width 200 mm, diameter 60
A 0 mm aluminum take-up roll was used.

As another winding condition, the relative position of the winding roll and the cooling roll at the time of capturing the front end of the ribbon is a direction 150 ° below the line connecting the nozzle tip ejecting the molten alloy and the center of the cooling roll. The take-up roll was arranged at the position rotated to the position. Also, after 0.5 seconds from the start of winding, 2.
The rotation speed of the winding roll was adjusted so that a load of 5 kgf was applied. Further, the distance between the winding roll and the cooling roll was initially set to 2 mm, and 2 seconds after the start of winding, the winding roll was retracted at a speed of 25 mm / sec for 10 seconds.

As a result of the casting experiment, the take-up roll was able to reliably capture the tip of the ribbon and take up the entire ribbon. The obtained ribbon has a width of about 150 mm and a plate thickness of about 30.
The thin ribbon had a good μm, and had good magnetic properties and mechanical properties. The tip of the obtained ribbon had a thin thickness of 20 μm or less over a length of about 20 m, but a ribbon having a smaller thickness than the target was obtained. Very little in the ribbon. From these results, it was found that by setting the ejection pressure at the start of casting to be smaller than a predetermined value, the ribbon can be reliably captured and the ribbon can be wound stably.

[Embodiment 2] Fe-Si _6.5 -B ₁₂ -C _{1 is} manufactured by using the apparatus for producing a single-roll ribbon in air used in Embodiment _1.
A ribbon of (atomic%) amorphous alloy was manufactured and an attempt was made to wind it with a winding roll. The nozzle opening shape of the molten alloy jet nozzle tip used in casting is 0.7 mm x 150
Two rectangular slits of mm were arranged at 1.5 mm intervals. As a casting condition, the surface speed of the cooling roll is 20 m
/ Sec.

The ejection pressure was controlled by the height of the tundish surface, but the height of the surface of the molten metal at the start of casting was set to 80 mm, and after the start of casting, that is, after the tundish stopper was released, 4
Immediately after the lapse of seconds, the amount of molten alloy supplied to the tundish was increased so that the height of the molten metal surface became 250 mm. Thereafter, the amount of molten alloy supplied to the tundish was controlled so that the height of the molten metal surface was maintained at 250 mm. The other casting conditions and winding conditions were the same as in Example 1.

As a result of the casting experiment, the take-up roll was able to catch the leading end of the ribbon without any problem and to wind up the entire ribbon.
The obtained ribbon has a width of about 150 mm and a plate thickness of about 5
The ribbon had a good thickness of 0 μm, and had good magnetic properties and mechanical properties. The leading end of the obtained ribbon was as thin as 20 μm or less over a length of about 20 m, but the length of the thin plate which was smaller than the target was obtained. Very little in the obi. From these results, it was found that by setting the ejection pressure at the start of casting to be smaller than a predetermined value, the ribbon can be reliably captured and the ribbon can be wound stably.

[0029]

Industrial production of rapidly solidified ribbons such as amorphous alloys is premised on online winding, but the method of the present invention ensures that the ribbon tip is secured at the start of winding the ribbon. Since it has become possible to capture thin ribbons, it has become possible to produce thin strips with a high yield.

[Brief description of drawings]

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

FIG. 2 is a schematic view showing how a thin strip obtained by the method of the present invention is wound up.

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

FIG. 4 is an enlarged schematic diagram for explaining a state of casting using a single roll rapid solidification ribbon production apparatus.

[Explanation of symbols]

 1 Molten Metal 2 Tundish 3 Tundish Stopper 4 Long Nozzle 5 Tuyere Brick 6 Intermediate Nozzle 7 Nozzle Holder 8 Melt Flow Path 9 Cooling Roll 10 Thin Strip 11 Winding Roll 11 ′ Preliminary Winding Roll 12 Disk 13 Support Roller 14 Nozzle tip 15 Enlarged internal space 16 Nozzle slit

Claims (1)

[Claims] 1. A method for producing a rapidly solidified ribbon by jetting liquid metals and alloys onto a moving cooling substrate, in which a jet pressure is made smaller than a predetermined value only at the start of casting, and immediately thereafter, a predetermined pressure is set. A method for producing a rapidly solidified ribbon, characterized in that casting is continued as a jet pressure.