JPS61176454A - Continuous casting device - Google Patents

Abstract

PURPOSE:To obtain a steel ingot having unidirectionally solidified structure by making a casting mold into such construction in which one end of the mold projects to a molten metal bath and the other end contacts with a cooling structural body and in which an inert gas blow port is directed toward the mold inside in the existing position of the molten metal prior to the solidification. CONSTITUTION:The graphite mold 6 is attached to the side wall in the bottom of a melting furnace 2 and a pure copper bar is inserted into the hole part of the mold 6 and after the bar is positioned, a prescribed amt. of the pure copper 1 is filled in the furnace and is held at a prescribed temp. Required water is passed to the cooling structural body 5 and an inert or neutral gas is ejected through an introducing port 4 into the position 10 of the pure copper 1 prior to the start of the solidification. The solidified casting rod 3 is drawn by pinch rolls 7. The steel ingot having the unidirectionary solidified structure is thus obtd. without the generation of breakout.

Description

[Detailed description of the invention] The present invention relates to a continuous metal casting apparatus.

In particular, it relates to a device that can easily achieve unidirectional solidification.

In continuous casting of metals, conventional equipment produces columnar crystals obtained by dendritic structures growing in the same direction.

It grows from the side wall of the mold toward the center of the casting, and equiaxed crystals often grow in the center. Further, foreign matter and the like accumulate inside the casting, causing many internal defects.

For this reason, during plastic working, when compressed in the direction of columnar crystal growth, some alloys may cause 9-grain boundary cracking, which is undesirable.

In order to solve this problem, a device has been proposed as in Japanese Patent Publication No. 55-46265, which heats the mold and solidifies it at the mold outlet, but it is easy to cause breakouts during operation, making it difficult to operate. . Furthermore, a heater was built into the mold to heat the mold itself, which was not a desirable structure.

In other words, the material requirements for manufacturing rods and the like as conductive materials for thin objects such as electric wires in equipment are as follows: 1. The material must have few internal defects such as foreign objects and pinholes.

2. It must be long and of uniform quality, with little segregation.

3. Columnar crystals should not grow towards the center of the rod.

There is a need for a continuous casting apparatus that can obtain products that meet the following conditions, and that also has safety, which is a necessary item during casting.

The present invention satisfies the above needs.

That is, one end of the mold protrudes into the molten metal bath, and the other end is in contact with the cooling structure, and an opening for blowing inert gas and/or neutral gas is provided where the molten metal exists before solidification begins. continuous casting equipment located within the mold.

Furthermore, the following is provided as an embodiment of the present invention.

The casting apparatus described above, wherein the material of the mold is a refractory material that is a good thermal conductor.

The casting apparatus described above includes a heat-retaining heating element provided between one end and the other end of the mold.

The present invention will be described in detail below.

Metals to which the device of the present invention is applied include copper, gold, silver, aluminum, zinc, lead, tin, and alloys thereof.

In particular, those with good thermal conductivity are preferred.

One end of the mold of the present invention projects into the molten metal bath.
By making the mold protrude, the mold is heated by the heat of the molten metal. This makes it possible to maintain a solidified surface on the inlet side of the molten metal without using a separate heating means or overheating. Also at the same time.

It enables unidirectional solidification and allows a cast structure with very large crystal grains to be obtained.

Furthermore, the other end of the mold is in contact with the cooling structure.

One-way solidification can be preferably performed by heating one end of the mold and cooling the other end.

At the same time, there is no molten metal at the mold outlet.
This enables continuous casting without breakouts.

Furthermore, by introducing a structure in which inert gas and/or neutral gas is blown into the mold at a position where the molten metal exists before solidification begins, it is possible to not only make the composition and temperature of the molten metal uniform, but also to Directional solidification is performed more preferably.

That is, if the gas comes into contact with a portion before solidification or during solidification, columnar crystals may appear from the wall surface, and unidirectional solidification may not be carried out favorably.

The inert gas and/or neutral gas introduction pipe is preferably provided so that the introduction hole in the mold is as short as possible. This is to prevent the temperature of the mold from decreasing due to the introduced gas.

Particularly in the case of vertical casting, the gas introduction hole preferably has a structure in which gas is blown into the molten metal just before solidification from the upper part of the melting furnace through an introduction pipe such as a ceramic pipe. This is because molten metal can enter the introduction pipe due to gravity and cause clogging.

In order to make the above continuous casting apparatus more preferable, it is preferable to use a refractory material with good thermal conductivity as the material for the mold. For example, silicon nitride, silicon carbide, graphite, etc.

Furthermore, it is preferable to provide a heat-retaining heating element between one end and the other end of the mold so that the temperature of the mold is not affected by the outside air, and preferably to surround the entire circumference of the mold.

Further, the casting apparatus used in the present invention may be one in which a mold is provided at the bottom of a melting furnace or a holding furnace, or one in which a mold is provided next to a side wall of a melting furnace or a holding furnace.

Regarding the size of products suitable for using the device of the present invention, those with very large diameters are not suitable. For example, products with a diameter of 20 m are not suitable.
The size is less than m. This is because the temperature of the mold is preferably within a range that can be transmitted to the molten metal or semi-solid metal in order to enable unidirectional solidification.

By implementing the present invention as described above, the following effects can be obtained.

(1) A long metal lump with a unidirectionally solidified structure can be obtained without the risk of breakout.

(2) It is possible to obtain a long metal lump that is free from foreign matter and pinholes.

(3) A unidirectionally solidified ingot with less segregation can be obtained. In particular, unidirectional solidification is preferably performed because inert gas and/or neutral gas is blown into the position before solidification starts.

(4) The surface of the ingot is extremely smooth.

(5) Due to unidirectional solidification, workability is extremely good.

(6) Since a long metal lump with large crystal grains can be obtained, it is suitable for manufacturing rods as materials for thin conductive wires such as electrical wires for equipment (for example, electrical wires for audio equipment).

Example 1 The experiment was carried out using the apparatus shown in FIG.

The end of a pure copper rod with an outer diameter of 10° and 6 mm is placed 1 cm inside the supply side of the molten metal (1) in a graphite mold (6) having an 11 mm diameter hole attached to the bottom side wall of the melting furnace (2).

50 kg of molten pure copper was placed in the furnace and maintained at 1250°C. Water was passed at a rate of 8 Q/min through the cooling structure (5) installed on the side opposite to the molten metal supply side, and the solidification position of the pure copper was set on the molten metal supply side in the mold.

In the graphite mold, as shown in FIG.

Gas is introduced from (4) to position (1) before the start of molten metal solidification.
0) directly. It stirred the molten metal and worked to eliminate variations in temperature and metal composition. Nao N2
A gas seal (8) was provided so that the gas was released only to the molten metal side.

The solidified rod was pinch rolled at 33 mm/min (
7), it was continuously pulled out.

The resulting pure copper was unidirectionally solidified and had extremely large crystal grains.

Example 2 When the apparatuses shown in FIGS. 2, 3, and 4 were used in the same manner as in Example 1, preferable unidirectionally solidified rods were obtained.

In addition, in FIGS. 3 and 4, a device equipped with a heat-retaining heating element (9) was used in order to reduce the influence of outside temperature.

This is the present invention. FIG. 2 shows a downward continuous casting apparatus. FIGS. 3 and 4 show the embodiments of FIGS. 1 and 2 in which a heat-retaining heating element is provided.

(1) Molten metal, (2) Melting furnace, (3) Casting rod, (4) N2 gas inlet, (5) Cooling structure, (6) Graphite mold (10) is an inert gas and/or neutral gas supply position.

Patent applicant: Day-1・°Otsugyo Co., Ltd. Agent Benguchi (7569) Kei Namikawa Figure 2

Claims (3)

[Claims] (1) One end of the mold protrudes into the molten metal bath, and the other end is in contact with the cooling structure, and the opening for blowing inert gas and/or neutral gas is in the presence of molten metal before solidification starts. A continuous casting device characterized in that the continuous casting device is located within a mold. (2) The continuous casting apparatus according to claim 1, wherein the material of the mold is a refractory material that is a good thermal conductor. (3) The continuous casting apparatus according to claim 1, characterized in that a heat-retaining heating element is provided between one end and the other end of the mold.