JPH0468065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a continuous casting device for a directionally solidified ingot, which continuously pulls out an ingot having a directionally solidified structure.

[Conventional technology]

In the field of acoustic copper wires and the like, copper wires having a unidirectional crystal structure in which grain boundaries extend in the axial direction of the copper wire are considered to have excellent acoustic effects. Conventionally, there are mainly two techniques as shown below as techniques for manufacturing copper wire having such a unidirectional crystal structure by continuous casting.

First, a cylindrical mold is attached to the outer side wall of a crucible that stores molten metal, and the molten metal comes into contact with a dummy bar inserted into the mold from the outside of the crucible, and the ingot that cools and solidifies is pulled out through the dummy bar. Cast the ingot. In this case, the mold is heated to a temperature higher than the melting point of the metal or alloy to be cast to prevent the formation of solidification nuclei on the mold wall,
It is cooled in one direction through a dummy bar and solidified in a region inside or outside the mold near the mold outlet. As a result, an ingot with a crystalline structure extending in the axial direction (pulling direction) is obtained. However, this method has the disadvantage that it is difficult to control the solidification rate because it is determined by three factors: the cooling position, the mold temperature, and the molten metal temperature.

On the other hand, by providing a mold in a crucible and immersing the mold in the molten metal in the crucible, the mold can be heated and kept warm by the molten metal, and an ingot having a unidirectional solidification structure can be used without the need for special heating means. There is also a technology for manufacturing (Japanese Patent Application Laid-Open No. 62-244553). In this technique, the control parameters are reduced to two, molten metal temperature and cooling, and the molten metal temperature is difficult to change due to the large heat capacity of the molten metal, so it is easy to control.

[Problem to be solved by the invention]

However, even in this conventional technology, the molten metal solidifies in the mold, so when the ingot is pulled out of the mold, the ingot slides against the mold, damaging the surface quality of the ingot, and causing wear of the mold. The inner diameter of the ingot fluctuates, making it extremely difficult to produce an ingot of sound quality. This is extremely disadvantageous compared to the case where an ingot with a unidirectionally solidified structure is obtained by heating the mold described above, in which an ingot with a mirror surface is obtained and no post-treatment is required. In addition, since the solidification interface is closer to the drawing direction than the inner surface of the crucible wall, the heat of the molten metal is transferred to the side wall of the crucible via the mold.
Furthermore, since this heat escapes from the side wall to the outside air, there is a problem that it is difficult to form a completely unidirectionally solidified structure.

The present invention has been made in view of such problems, and is capable of stably casting a unidirectionally solidified ingot that has excellent surface quality and has a uniformly unidirectionally solidified structure inside. The purpose of the present invention is to provide continuous casting equipment.

[Means to solve the problem]

The continuous casting device for unidirectionally solidified ingots according to the present invention includes a container storing molten metal and a cylinder protruding into the container from the side wall of the container, and continuously casts solidified ingots from the cylinder. In a continuous casting device for unidirectionally solidified ingots that is pulled out, the cylinder body is placed in a first position inside the container.
and a second region on the outer side of the container, the inner diameter of which is larger than the first region, and the boundary between the first region and the second region is wider than the inner surface of the side wall of the container. It is characterized by being located inside the container.

[Effect]

In the present invention, since the cylindrical body is placed in a container storing molten metal, the cylindrical body is heated and kept warm by the heat of the molten metal, so that the molten metal can be used as a solidified ingot (or It is cooled only by unidirectional heat transfer to the starting rod and solidifies in the first region. Since the solidified ingot does not come into contact with the second region of the cylindrical body, which has an inner diameter larger than the first region, the surface of the ingot does not slide on the inner surface of the cylindrical body and the surface quality thereof does not deteriorate. Furthermore, since the boundary between the first region and the second region is located closer to the inside of the container than the inner surface of the side wall of the container, the solidification interface is within the molten metal within the container, so the heat of the molten metal is transferred through the side wall of the container. It does not become discrete. Therefore, at the solidification interface, the molten metal is cooled only in the direction of drawing the ingot,
The structure becomes almost completely unidirectionally solidified.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a continuous casting apparatus for unidirectionally solidified ingots according to an embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view showing an enlarged nozzle portion thereof. In the crucible 1, for example, a molten metal 2 of aluminum heated and maintained at a temperature of about 690°C or a molten metal 2 of copper heated and maintained at a temperature of about 1110°C is stored. A cylindrical nozzle 3 made of carbon or the like is disposed at the upper part of the side wall of the crucible 1. This nozzle 3 is fixed to the side wall 1a with its axial direction horizontal so as to protrude from the side wall 1a of the crucible 1 to the inside of the crucible 1.

The nozzle 3 has a uniform outer diameter, but the inner diameter is different between the region on the inside of the crucible, the region on the side wall of the crucible, and the region between these regions and the region in between. The region is, for example, the smallest with an inner diameter of 6.3 mm, and the region is the largest with, for example, an inner diameter of 9.5 mm. and,
In the region, the diameter gradually increases from the region side toward the region side. For example, the length of this region is 25 mm, the length of the region is 5 mm, and the length of the region is 10 mm. Such a nozzle 3 is disposed on the side wall 1a so that the boundary between the regions is closer to the inside of the crucible 1 than the inner surface 1b of the crucible side wall 1a. For example, the distance L between the boundary and the inner surface of the side wall 1b is 3 mm.

A cooling water spray nozzle 6 is disposed near the outlet of the nozzle 3, and the starting rod 4 or ingot 5 pulled out from the nozzle 3 is cooled by spraying water. ing.

Next, the operation of the continuous casting apparatus for unidirectionally solidified ingots configured as described above will be explained. First, a starting rod 4 having a diameter of 6 mm, for example, is inserted into the nozzle 3, and its tip is positioned slightly closer to the area than the boundary between the areas of the nozzle 3. After that, add molten metal, etc.
The surface of the molten metal is brought above the top surface of the nozzle, and at this time, the starting rod 4 is brought into contact with the molten metal introduced into the nozzle to melt its tip. Then, the molten metal 2 in the area becomes the starting rod 4.
When the starting rod 4 is cooled and solidified, the starting rod 4 is moved from the nozzle 3 to the outside of the crucible by, for example, 60 mm/
Draws out at a speed of 1 minute. Since this starting rod 4 is cooled by a jet of cooling water from a spray nozzle 6, a rod-shaped ingot 5 having the same diameter as the inner diameter of the area is continuously solidified in the starting rod 4. Then it is pulled out.

In this case, since the region of the nozzle 3 is immersed in the molten metal in the crucible 1, the molten metal 2 in the region
Since the melt is kept warm by all the molten metal in the crucible 1, which has a large heat capacity, its temperature is extremely stable. Since the starting rod 4 and the ingot 5 that have already been drawn out are cooled by the cooling water jet from the spray nozzle 6, the molten metal 2 within the area is heated by the starting rod 4 or the ingot 5. The heat is removed and solidified. Moreover, since the boundary between the regions is located inside the crucible 1, that is, inside the molten metal 2, rather than the inner surface 1b of the side wall of the crucible 1,
The solidification interface is located inside the crucible from this inner surface 1b. Therefore, the heat of the molten metal that is about to solidify is transmitted to the crucible side wall 1a, and the heat is not dispersed to the side wall 1a. For this reason, heat removal at the solidification interface is carried out exclusively by the starting rod 4 or the ingot 5.
Therefore, a substantially complete unidirectionally solidified ingot extending in the axial direction of the ingot is obtained.

Furthermore, if the boundary between these regions is outside the crucible inner surface 1b of the side wall, the nozzle 3 in the region will solidify in the middle of the region.
Since the inner surface of the ingot 5 slides, the surface quality of the ingot deteriorates. In contrast, in this embodiment, since the boundary is located inside the crucible rather than the inner surface of the side wall 1b, the ingot 5 does not solidify in the middle of the region and has excellent surface properties (mirror finish, etc.). can be obtained.

[Effects of the Invention] According to the present invention, an ingot with excellent surface properties can be obtained, eliminating the need for dust removal work after casting, and
Sliding on the inner surface of the mold (nozzle) prevents the ingot from breaking during casting, resulting in a long ingot with excellent continuity. Further, since the molten metal is almost completely cooled by heat transfer in the axial direction of the ingot, a high quality unidirectional solidification structure can be obtained.

In this embodiment as well, there are two control items: molten metal temperature and cooling, and since the molten metal temperature has a large heat capacity and is difficult to change, control is extremely easy.

Further, the present invention is not limited to the above embodiments, and various modifications are possible. For example, in the above embodiment, the first region is composed of regions and the second region is composed of regions, but only the region may be formed as the second region.

In other words, it is not necessary to directly connect the first region (region) with a small inner diameter and the second region (region) with a large inner diameter, and to provide a region whose diameter gradually increases like a region.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a unidirectionally solidified ingot casting apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing a nozzle portion thereof. 1; crucible, 1a; side wall, 1b; inner surface, 2; molten metal, 3; nozzle, 4; starting rod,
5; Ingot.

Claims (1)

[Claims] 1. A continuous casting device for unidirectionally solidified ingots, which has a container storing molten metal and a cylindrical body protruding from the side wall of the container into the container, and continuously pulls out solidified ingots from the cylindrical body. The cylindrical body is the first one on the inside of the container.
and a second region on the outer side of the container, the inner diameter of which is larger than the first region, and the boundary between the first region and the second region is wider than the inner surface of the side wall of the container. A continuous casting device for unidirectionally solidified ingots, characterized in that it is located inside a container.