JPS59133950A - Vertical type continuous casting device - Google Patents

Abstract

PURPOSE:To draw out efficiently a continuously cast ingot having fine crystal texture by providing a cooler in the molten metal well part of a vertical type continuous casting device, depositing a seed crystal on the inside wall of a casting mold, detaching the crystal by a mechanical means and feeding the same to a molding part. CONSTITUTION:A cooler 7 is provided as circumscribed to an inside wall 8 in a molten metal well part A in a vertical continuous casting device for an Al billet, etc. The cooler 7 is so disposed that the cooling surface thereof forms directly the inside wall of the part A. A refrigerant is run in the cooler 7 to cool the inside wall 8 of the casting mold in this part so that a crystal is deposited on the wall 8. The crystal is then stripped from the wall 8 by operating a seed crystal stripping means 10 sliding vertically along the wall 8. The stripped crystal is made to arrive at a casting ingot molding part B as the molten metal flows downward. An adequate amt. of the seed crystal is thus easily fed to the solidifying zone of the casting ingot and the continuously cast ingot having uniformly fine crystal texture is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for efficiently producing continuous ingots having a fine crystalline structure, and is a vertical continuous casting apparatus in which a seed crystal supply mechanism is provided in the reed, particularly in the molten metal sump. It is related to the device.

In general, vertical continuous casting equipment uses a cylindrical mold with open top and bottom, and the molten metal is supplied from above the mold onto a platform that can be raised and lowered at the open end of the lower part of the mold, and the molten metal is initially solidified within the mold. Let me.

Then, by successively lowering the pedestal.

A continuous ingot is obtained by continuously pulling out the ingot from the lower open end of the mold while cooling the ingot with a coolant such as water sprayed from a cooling water distribution device or the like provided below the mold.

Continuous ingots produced by such equipment are normally used as raw materials for processing such as rolling, extrusion, and casting.In recent years, as quality requirements for cast materials for these processes have increased, the crystal structure has become fine and uniform. It is desired that there be no internal defects.

The most common method for refining continuous ingots is to add a crystal refining agent in the smelting furnace, but when this method is used, the crystal refining agent mixed into the molten metal is It is undesirable to reduce quality.

In order to solve the above problems with ingots, a cooler was inserted into the molten metal pool of the continuous casting mold, and by applying ultrasonic vibration or electromagnetic stirring to the cooler, the seed crystals deposited on the cooler surface were separated and settled. A method of supplying molten metal to the solidification zone has been proposed.

However, these methods can be applied to small-diameter ingots and low casting speeds, but when casting large-diameter ingots or high casting speeds even for small-diameter ingots, it is necessary to use a large amount of seed crystals. Because supply is difficult.

It also had drawbacks such as low effectiveness and high capital investment.

The present invention provides a cooler for cooling the inner wall of the mold at an appropriate location in the molten metal sump of a continuous casting mold, deposits seed crystals on the inner wall, and scrapes off the seed crystals by mechanical means to form an ingot. In other words, we succeeded in supplying a large amount of seed crystals to the molten metal solidification region.

That is, 1. the present invention comprises a cylindrical mold in which a molten metal sump portion and an ingot shaping portion are sequentially formed from top to bottom and which are open at the top and bottom, and a pedestal that is inserted into the lower open end of the mold and is movable up and down. As a result, the molten metal supplied from above the mold passes through the molten metal sump and solidifies in the ingot forming section below, while the ingot is successively lowered to open the bottom of the mold. In a continuous casting machine that pulls out from the end.

It is characterized by providing a seed crystal precipitation zone equipped with a cooler for cooling the mold inner wall at an appropriate location of the mold in the molten metal sump, and a seed crystal removal means that moves up and down along the mold inner wall of the zone. This is a vertical continuous stitching device.

Hereinafter, the present invention will be explained in detail with reference to the drawings showing the embodiments thereof.

Figure 1 shows an overall conceptual diagram of the apparatus when the present invention is applied to a mold for continuous casting of a single billet pouring method, and Figure 2 shows an example of the mechanical peeling means used therein. FIG. 6 is an enlarged drawing showing an overall conceptual diagram of an apparatus according to another embodiment of the present invention.

As can be seen in the drawing, the present invention has a ladle placed above a cylindrical mold (1) with open upper and lower sides, in which a molten metal reservoir (A) 2 and an ingot forming part (B) are sequentially formed from top to bottom. The molten metal (2) from the tundish is supplied by a molten metal supply means (3) using a branch pipe of a tundish, a molten metal bucket, etc., and is lowered to the ingot forming part (B) via the molten metal dripping part (A), @ In the ingot forming section (B), the molten metal is cooled and solidified by a refrigerant such as water discharged from the water cooling jacket or its slits, and the ingot (
In a continuous casting apparatus designed to continuously cast 6), a cooler (7) is provided in the molten metal reservoir (A) so as to circumscribe the inner wall (8) (Fig. 1). ) is installed so that the cooling surface of the molten metal sump (A) directly constitutes a part of the inner wall of the molten metal sump (A) (Fig. 3) to form a first type crystal precipitation zone. By flowing a suitable coolant such as air, the inner wall (8) of the mold in this area is cooled, and crystals are precipitated from the molten metal in this zone onto the inner wall (8). By operating the seed crystal exfoliating means αQ that slides up and down, the crystal is exfoliated from the inner wall (8).

As the molten metal flows downward, the crystals are caused to reach the ingot forming part (B).

The inner wall (8) of the molten metal reservoir (A) is of course made of a refractory material that does not react with the molten metal, and is preferably made of a material that can withstand sliding against the glue, especially the crystal exfoliation means. Examples include ceramic materials such as silicon.

Water, air, etc. are used as the refrigerant flowing through the cooler (7), and the refrigerant temperature and flow rate are maintained such that the inner wall temperature is approximately 0.5 to 3°C lower than the solidification temperature of the molten metal. If the zero temperature difference is less than 0.5°C, a sufficient amount of crystals will not be deposited on the inner wall, and if it exceeds 6°C, it will be difficult to exfoliate the precipitated crystals.

In addition, the width of the seed crystal precipitation zone, the precipitation zone and the ingot forming part (B
) is the type of metal/alloy to be cast.

It is appropriately selected depending on the size of the ingot, the casting speed of the ingot, etc.

In addition, in the present invention, it is also possible to embed a temperature sensor at an appropriate location in the inner wall (8) of the molten metal pool, and adjust the refrigerant flow rate and temperature of the cooler (7) based on the detected temperature. Moreover, the series of operations can be automated by adding a device that interlocks and adjusts the casting speed and the sliding speed of the peeling means QI.

The seed crystal exfoliating means αQ exfoliates the crystals that have crystallized on the inner wall of the mold in the seed crystal precipitation zone from the precipitation surface and supplies them as seed crystals to the ingot forming section (B). A) It is installed on the inner wall so that it can be moved up and down or rotated and slid. aυ is its driving device, and D and Q3 are support rods that connect the two.

FIGS. 2(a) and 2(b) illustrate seed crystal exfoliation means, in which (a) is a ring-shaped member and a shingle, and (b) is a wing-shaped member. When the stripping means α0 is ring-shaped, a flow hole α■ is formed in the center, and a taper (14
) to prevent seed crystals from being deposited on the upper surface of the ring-shaped body.

The stripping means a1 is preferably made of a molten metal resistant ceramic material such as silicon nitride or silicon carbide, and the clearance between its sliding surface and the inner wall of the mold is desirably 5 ml or less, preferably about 0.5 to 3 ml.

Since the continuous casting apparatus of the present invention is configured as described above, seed crystals can be supplied to the solidification zone extremely simply and at low cost compared to conventional apparatuses using ultrasonic vibration, electromagnetic stirring, etc. Moreover, by appropriately adjusting the width of the seed crystal precipitation zone, cooling conditions, etc., it is extremely easy to add the appropriate amount of seed crystals to the ingot according to the diameter of the ingot, casting speed, etc. It has excellent features such as being able to supply it to the coagulation zone.

Next, an example of continuous casting of an aluminum billet using the apparatus of the present invention will be described.

The ingot forming part (B) is composed of a copper water-cooled mold, and the molten metal reservoir part (A) above it is composed of a cylindrical silicon carbide refractory material with an inner diameter of 157 m and a length of 500 cm. A ring-type stainless steel cooler (7) having a contact surface with a width of 50 m is placed approximately in the middle of the molten metal sump and is in circumscribed contact with the mold (1) as shown in Figure 1, excluding the cooler installation area. The periphery of the molten metal sump (A) is covered with an alumina refractory material, and a ring-shaped seed crystal made of silicon carbide that slides up and down with clearance 2 on the inner wall (8) of the molten metal sump (A) is exfoliated. Using a continuous casting device equipped with a means, molten 618 aluminum alloy at 715°C was continuously poured from a tub (3) placed above the mold (1).

When room temperature air was circulated through the cooler (7), the molten metal sump part (A) had a gap of about 30 mm vertically relative to the width of the cooler (7).
A seed crystal precipitation zone appeared in the expanded width, and seed crystals were deposited over a width of about 110 m.

Next, the seed crystal exfoliating means αQ was moved up and down at a rate of 6 times per minute to exfoliate the crystals deposited on the inner wall (8).

When the process starts, the casting speed of the ingot is 100. The pedestal (4) was lowered so that the casting temperature was 1 min, and the ingot was continuously pulled out from the lower end of the water-cooled mold to obtain a continuously cast ingot.

A part of the obtained ingot was cut and a macrostructure test was performed on the cut surface, and the crystal grain size of the ingot was 400 to 800 μm.
The ingot contained very fine crystals, and there was almost no difference in grain size between the central part and the peripheral part of the ingot.

For comparison, continuous casting was carried out under almost the same conditions using the same equipment with the seed crystal supply mechanism stopped, and a macrostructure sample was obtained from a part of the ingot, and the crystal grain size was 1~'
10 sieves, and the distribution tended to become coarser towards the center.

From the above results, it is clear that when using the apparatus of the present invention, a continuous ingot having a uniform and fine crystal structure can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an overall conceptual diagram showing one embodiment of the apparatus of the present invention. FIG. 2 is an enlarged perspective view of the seed crystal exfoliating means in the apparatus of the present invention, FIG. 2-a is a partially cutaway perspective view of the ring-shaped exfoliating means, and FIG. 2-b is a perspective view of the vane-like exfoliating means. It is. FIG. 3 is an overall conceptual diagram showing another embodiment of the device of the present invention. DESCRIPTION OF SYMBOLS 1... Mold, 2... Molten metal, filter... Molten metal supply means 4... Receiver, 6... Continuous casting ingot, 7... Seed crystal precipitation cooler 110. ... Seed crystal exfoliation means, 11.・
... Drive means, A... Molten metal reservoir, B... Ingot forming section Patent applicant Nippon Light Metal Co., Ltd. Figure 1 Figure 2 (a) (b)

Claims (1)

[Claims] (1) A cylindrical mold in which a molten metal sump portion and an ingot forming portion are sequentially formed from top to bottom, and the top and bottom are open. A cradle that can be raised and lowered is inserted into the lower open end of the mold.
The molten metal supplied from above the mold passes through the molten metal pool and solidifies in the ingot forming section below, and by sequentially lowering the pedestal, the ingot is continuously moved from the open end of the lower part of the mold. In a continuous casting device that is designed to be drawn out, a seed crystal precipitation zone is provided with a cooler for cooling the inner wall of the mold at an appropriate location of the mold in the molten metal sump, and a seed crystal slides along the inner wall of the mold in the zone. A vertical continuous casting device characterized by being provided with a stripping means.