JP4655994B2 - Vertical casting apparatus for aluminum and vertical casting method using this casting apparatus - Google Patents

Description

  The present invention relates to a vertical continuous casting apparatus for continuously casting aluminum and a vertical continuous casting method using the casting apparatus.

  Generally, this type of vertical continuous casting apparatus (DC continuous casting apparatus) used for continuous casting of an aluminum alloy has an upper mold for forcibly cooling the molten metal from its surroundings, and the upper mold by gradually lowering the upper mold. It has a lower mold that continuously draws out the ingot that solidifies in the mold, controls the height of the molten metal in the upper mold by float (float casting), and cools it from the discharge port provided at the bottom of the upper mold The ingot is rapidly cooled by spraying water toward the ingot (see, for example, Patent Documents 1 to 3).

  In such a vertical continuous casting apparatus, if the distance from the height at which the cooling water sprayed from the discharge port is applied to the ingot to the molten metal surface in the upper mold (hereinafter referred to as “effective mold length”) is shortened. It is known that the reverse segregation phase of the surface of a cast product (hereinafter referred to as “billette”) generally becomes thinner and a smoother surface can be obtained. That is, in the ingot that is solidified by forced cooling, the surface layer portion is gradually cooled and solidified by being indirectly cooled by the upper mold cooled by cooling water, so this gradually cooled portion tends to have a relatively coarse crystal structure. . On the other hand, the portion that is directly cooled and solidified by the contact with the cooling water becomes a rapidly cooled portion, and thus tends to have a relatively fine structure. For this reason, when the effective mold length is increased, the thickness of the coarse crystal structure (unhealthy portion) of the billet surface layer portion is increased accordingly (Patent Document 1). In addition, the solidified ingot contracts due to contact with the upper mold and leaves the upper mold. As a result, an air layer is formed between the upper die and the ingot, and cooling from the upper die is weakened. At this time, if the effective mold length is long, the state where the cooling is weak becomes long, so that the surface layer portion is redissolved, the surface roughness becomes rough, and the appearance quality may be deteriorated.

  For these reasons, it is preferable to make the effective mold length as short as possible. However, in that case, if the effective mold length is simply shortened, solidification will occur even at the top of the molten metal, the molten metal surface height will be lowered, the float will be lowered and close to the cooling water discharge port, and the float will solidify in the rapidly cooled part of the ingot Since it contacts and adheres, the problem that it becomes impossible to cast arises. For this reason, there is a limit to shortening the effective mode length.

  As a measure for solving such a problem, the present applicant has proposed a continuous casting mold described in Patent Document 1. In this continuous casting mold, a refractory ring made of a cylindrical body integrally provided with a ridge at the upper end is mounted in the upper end opening of the upper mold. According to such a mold, the effective mold length can be substantially shortened by the ring-proof, so that a smooth surface can be obtained with a fine structure.

JP 2000-15399 A JP-A-3-452 JP-A-2-307649

  When a difficult-to-cast alloy such as an aluminum alloy for cutting to which a low melting point element (Pb, Bi, Sn, etc.) is added is float cast, the low melting point element oozes out to the surface of the ingot. Therefore, inferiority of the above-described ingot surface layer portion is particularly likely to occur as compared with other aluminum alloys.

  On the other hand, according to the casting apparatus of the above-mentioned patent document 1, since the effective mold length can be substantially shortened by the refractory ring, the surface property of the ingot can be improved as compared with the float casting. However, as a result of actual implementation, the efficiency is not sufficient, and there is a problem that the surface property is largely uneven due to lack of certainty or reproducibility. The reason is considered to be that the surface property of the ingot becomes rough when the ingot comes into contact with the inner wall surface of the upper mold.

  Therefore, the present inventors diligently studied, and in the casting of Patent Document 1, it is possible to prevent the ingot from substantially contacting the inner wall surface of the upper mold when a specific condition is satisfied. It was found that an ingot having a good surface property can be obtained. This is a finding newly found by the present inventors. Therefore, as a result of further research, a tapered surface that expands downward is formed on the inner wall surface on the lower end opening side of the refractory material that is attached to the upper mold, and the inclination angle of the tapered surface and the upper mold The horizontal distance from the inner wall surface to the lower end of the tapered surface and the vertical distance from the height position where the cooling water sprayed from the cooling water discharge port is applied to the ingot to the lower end of the refractory material are set to optimum dimensions. Then, even if it is a difficult-to-cast alloy such as a cutting aluminum alloy to which low melting point elements (Pb, Bi, Sn, etc.) are added as well as general aluminum, the solidified ingot is substantially formed on the inner wall surface of the upper mold. It has been found that an ingot having a good surface property can be cast without being brought into contact with each other.

  The present invention has been made to solve the above-described problems caused by the prior art, and an object of the present invention is to provide a vertical continuous casting apparatus capable of casting a cast product having a very good surface property and the casting apparatus. Another object of the present invention is to provide a vertical continuous casting method using the above.

  In order to achieve the above object, an aluminum vertical casting apparatus according to the present invention forms a casting space into which molten metal is introduced and a hollow portion through which cooling water passes, and the cooling water in the hollow portion is formed at the bottom. An upper mold that has a discharge port that injects obliquely downward and inward, forcibly cools the molten metal in the casting space from its periphery, and is inserted into the casting space of the upper mold from above A hollow refractory material placed on or above the upper mold and an ingot that solidifies in the upper mold by being gradually lowered at the lower position of the upper mold are continuously drawn below the upper mold. In the vertical continuous casting apparatus provided with a mold composed of a lower mold, the lower end opening side of the refractory material is substantially similar to the shape of the ingot, and is a tapered surface that expands downward on the inner peripheral surface. And the inner wall of the upper mold has an inclined angle of 45 ° to 80 °. The horizontal distance from the surface to the lower end of the tapered surface is 2 to 50 mm, and the vertical distance from the height position where the cooling water sprayed from the discharge port is applied to the ingot to the lower surface of the refractory material is 5 to 80 mm. Is set.

  Further, the vertical casting apparatus for aluminum casting according to claim 2 of the present invention is provided with a cooling water discharge port below the upper mold instead of providing a cooling water discharge port at the bottom of the upper mold. is there.

  Moreover, the vertical casting apparatus for vertical casting of aluminum according to claim 3 of the present invention is such that the thermal conductivity of the refractory material is 50 W / m · K or less.

  Further, in the vertical casting apparatus for aluminum according to claim 4 of the present invention, the refractory material is mainly composed of at least one of calcium silicate, fiber ceramics, alumina / silica mold material, and fused silica. It is what. The refractory material may be a combination of two or more refractory materials.

  A vertical continuous casting method according to claim 5 of the present invention is a method of casting aluminum or an aluminum alloy using the vertical continuous casting apparatus, wherein the lower mold lowering speed in a steady state is 20 to 500 mm. / Min is set to cast aluminum or an aluminum alloy.

  Moreover, the vertical casting method of the aluminum alloy according to claim 6 of the present invention is a casting method using the vertical casting apparatus, and any one or more of Pb, Sn, and Bi is set to 0. . Cast aluminum alloy containing 2% by mass or more.

  Moreover, the vertical casting method for aluminum according to claim 7 of the present invention is a casting method using the vertical casting apparatus, and includes 5.0 to 6.5 mass% of Cu, Pb, Sn. , Bi contains 0.2% by mass or more of any one of Bi, and the remainder is casted from an aluminum alloy composed of aluminum and inevitable impurities.

  Furthermore, the vertical casting method of an aluminum alloy according to claim 8 of the present invention is a casting method using the vertical casting apparatus, wherein Si is 2 to 4% by mass and Cu is 0.2 to 0. .8% by mass, Mg: 0.4 to 1.6% by mass, Cr: 0.05 to 0.6% by mass, Ti: 0.02 to 0.25% by mass, with the remainder consisting of aluminum and inevitable impurities It casts an aluminum alloy.

  In the continuous casting of aluminum or aluminum alloy, the main cause of the deterioration of the surface properties of the ingot is the contact between the mold and the ingot. That is, when the molten metal is forcibly cooled and solidified, it contracts to become an ingot and leaves the upper mold. When separated from the upper mold, an air layer is formed between the upper mold and the ingot, and the cooling capacity from the upper mold is reduced. Then, the ingot surface may be remelted by the heat inside the molten metal that has not yet solidified. Then, when the remelted molten metal comes into contact with the inner wall surface of the mold and cools down, it solidifies again and roughens the surface. Further, the surface of the ingot immediately after solidification is very soft, and if the friction with the mold is large, the surface of the ingot is damaged. In particular, such remelting frequently occurs in aluminum alloys containing low melting point elements such as Pb, Sn, Bi, etc. like free-cutting alloys. Si is an element that improves the strength of the aluminum alloy. However, if it exceeds 2% by mass, the coexisting temperature range of the solid phase and the liquid phase becomes narrow, so that metal leakage due to remelting is likely to occur.

  On the other hand, as in the present invention, a tapered surface having a divergent shape that expands downward is formed on the inner wall surface of the opening on the lower end side of the refractory material, and the inclination angle of this tapered surface is 45 ° to 80 °. The horizontal distance from the inner wall surface of the casting space of the upper mold to the lower end of the tapered surface is 2 to 50 mm, and the lower end of the refractory material from the height position where cooling water sprayed from the discharge port is applied to the ingot When casting at a normal casting speed of 20 to 500 mm / min with a vertical distance of 5 to 80 mm, the molten metal is held by the surface tension during casting and hardly touches the inner wall surface of the casting space. Since it solidifies, the cooling capacity does not become weak after solidification, so that it is possible to cast a cast material having excellent surface properties without being re-dissolved and without defects due to friction with the inner wall surface.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a vertical continuous casting apparatus according to the present invention, and FIG. 2 is an enlarged cross-sectional view for explaining a main part of the casting apparatus. In these drawings, a vertical continuous casting apparatus generally indicated by reference numeral 1 includes an upper mold 2, a lower mold 3, a refractory material 4, a float 5, and the like. In the present embodiment, the molten metal is supplied to the mold using a float, but the molten metal may be supplied as in hot top casting.

  The upper mold 2 is formed in a hollow ring shape with aluminum, copper or the like, and a casting space 11 into which a molten metal 13 of aluminum or an aluminum alloy (also referred to as aluminum generically) is put. And the hollow part 12 to which the cooling water 14 is supplied is formed. Further, a slit-like discharge port 16 is formed on the bottom surface of the upper mold 2 to inject the cooling water 14 in the hollow portion 12 obliquely downward and inward. The casting space 11 is constituted by the center hole of the upper mold 2 and is opened up and down. The hollow portion 12 is a sealed space surrounded by the inner / outer walls 17A and 17B, and the annular upper plate 18A and the bottom plate 18B. The discharge port 16 is formed obliquely closer to the inner periphery of the bottom plate 18B so that the lower end opening is closer to the center of the upper mold 2 than the upper end opening. Such a discharge port 16 may be a continuous slit or may be formed by a large number of small holes that are discontinuously drilled in the circumferential direction of the bottom plate 18B.

  The lower mold 3 is composed of a rod 3A that can be moved up and down by a lifting device such as an air cylinder (not shown), and a disc-shaped lower mold body 3B that is integrally provided at the upper end of the rod 3A. The lower mold body 3B has an outer diameter substantially equal to the hole diameter of the casting space 11 of the upper mold 2 and closes the lower end opening of the casting space 11 at the start of casting. Is started, the ingot 21 that has been gradually lowered and solidified is continuously drawn out below the upper mold 2.

  The refractory material 4 is inserted into the casting space 11 of the upper mold 2 from above, so that the cylindrical portion 4A that covers the inner wall surface of the casting space 11 (also referred to as the inner wall surface of the upper mold 2), and this cylinder It is comprised by the flange part 4B integrally connected by the outer peripheral surface upper end part of the part 4A. The cylindrical portion 4A is formed with an outer diameter smaller than the hole diameter of the casting space 11, and an annular protrusion 22 is integrally projected at the lower end portion of the outer peripheral surface. The annular protrusion 22 is opposed to or close to the inner wall surface of the casting space 11 by fitting the cylindrical portion 4 </ b> A into the casting space 11, and regulates the radial displacement of the refractory material 4. . Further, the length of the cylindrical portion 4A is set shorter than the height of the upper mold 2. For this reason, the lower part of the inner wall surface of the casting space 11 is not covered with the refractory material 4. On the other hand, a divergent tapered surface 23 is formed on the inner peripheral surface of the lower end side opening of the cylindrical portion 4A. The flange portion 4B is placed on the upper plate 18A by inserting the cylindrical portion 4A into the casting space 11. A well-known oil droplet mechanism may be provided in the space between the refractory material 4 and the upper mold 2.

  Such a refractory material 4 does not need to be firmly fixed to the upper mold by bolts or the like as in the refractory material used in the conventional hot top casting apparatus, and is not the upper mold 2 of the conventional float casting apparatus. It is only necessary to insert into the casting space 11, and it is not necessary to manufacture a new casting apparatus. Moreover, you may process the refractory material of a hot top casting apparatus, and you may use it for the casting apparatus 1 of this invention.

  As the material of the refractory material 4, in order not to lower the temperature of the molten metal 13, it is a material mainly composed of at least one of calcium silicate, fiber ceramics, alumina / silica mold material, fused silica, or heat conduction. It is formed of a material having a rate of 50 W / m · K or less. In addition, the heat conductivity of the refractory material 4 means the heat conductivity of the part which contacts a molten metal.

  Since the float 5 has been widely known in the past, description of its configuration and the like is omitted here.

The vertical continuous casting apparatus 1 having such a structure is configured in substantially the same manner as the conventional casting apparatus shown in Patent Document 1, but in the present invention, solidified by forced cooling of the molten metal 13 in particular. In order to prevent the cast ingot 21 from substantially contacting the inner wall surface of the casting space 11 that is the hole wall of the upper mold 2, the casting speed and the dimensions of each part (α, w ₁ , w ₂₎ ) Is clearly specified, and this point is clearly different from the conventional apparatus of Patent Document 1. That is, the casting speed during casting (the lowering speed of the lower mold 3) is set to 20 to 500 mm / min.

  In continuous casting by the vertical continuous casting apparatus 1, the casting speed is slow immediately after the start of casting, but after a certain time has elapsed, the speed is increased, and after reaching a certain speed, the casting speed is constant. Casting with This constant casting speed is called steady state. When the casting speed at this steady state is set to 20 mm / min or more, casting can be performed because the ingot 21 is in contact with and held by the refractory material 4 even if the molten metal 13 is not in contact with the upper mold 2. . When the casting speed is less than 20 mm / min, the molten metal is solidified at the portion of the refractory material 4, which is not preferable. On the other hand, if the casting speed exceeds 500 mm / min, the cooling is too fast and the casting cannot be performed, which is not preferable.

  Further, the present invention provides a taper surface that is widened toward the inner wall surface of the lower end side opening of the refractory material 4 so that the molten metal 13 and the solidified ingot 21 do not substantially contact the inner wall surface of the upper mold 2. 23, and the inclination angle (intersection angle with the horizontal surface) α of the tapered surface 23 is set to an angle of 45 ° or more and 80 ° or less, more preferably 60 ° ≦ α ≦ 70 °. If the angle α of the tapered surface 23 is less than 45 °, it is not preferable because the cooling water 14a is blown up and the ingot 21 is constricted. If the inclination angle α is larger than 80 °, the molten metal cannot be held by the surface tension, which is not preferable. The length L of the tapered surface 23 is preferably within a range of 10 to 30 mm. Within this range, it becomes difficult for the molten metal 13 of aluminum or aluminum alloy to contact the lower part of the inner wall surface of the casting space 11 of the upper mold 2.

The horizontal distance W ₁ from the inner wall surface of the casting space 11 of the upper mold 2 to the lower end of the tapered surface 23 is set to 2 to 50 mm, and the cooling water 14a injected from the discharge port 16 of the upper mold 2 is ingot 21. The vertical distance W ₂ from the height position P to the outer periphery of the refractory material 4 to the lower surface of the refractory material 4 is set to ₅ to 80 mm.

  On the other hand, the conventional apparatus shown in Patent Document 1 has a high molten metal surface height, and the distance from the lower end of the refractory material to the lower end of the upper mold is too long. The casting surface becomes rough by contacting the inner wall surface of the upper mold.

If the horizontal distance W ₁ is less than 2 mm, the molten metal 13 or the ingot 21 comes into contact with the inner wall surface of the upper mold 2, which is not preferable. If the horizontal distance W ₁ is greater than 50 mm, the cooling water 14a is difficult to reach the ingot 21 and the rapid cooling effect is reduced, which is not preferable. A more preferable horizontal distance W ₁ is 3 mm to 10 mm.

If the vertical distance W ₂ is less than 5 mm, the cylindrical portion 4A of the refractory material 4 becomes long, and the molten metal 13 is solidified in contact with the tapered surface 23, which is not preferable. If the vertical distance W ₂ is larger than 80 mm, the height position P where the cooling water 13a is applied to the outer periphery of the ingot 21 is lowered, and the rapid cooling effect by the cooling water 14a is lowered, which is not preferable. More preferred horizontal distance W _2, is 15Mm～35mm.

Thus, in the present invention, the casting speed of the continuous casting apparatus 1 (lower mold lowering speed) is 20 to 500 mm / min, the inclination angle α of the taper surface 23 is 45 ° to 80 °, and the upper mold 2 The horizontal distance W ₁ from the inner wall surface to the lower end of the taper surface 23 is 2 to 50 mm, and the refractory material 4 starts from a height position P at which the cooling water 14a injected from the discharge port 16 of the upper mold 2 is applied to the outer periphery of the ingot 21. Since the vertical distance W2 to the lower surface of the upper mold 2 is set to ₅ to 80 mm, the ingot 21 pulled out below the upper mold 2 at the time of casting can be pulled out without contacting the lower part of the inner wall surface of the upper mold 2. it can. That is, the molten metal 13 in the upper mold 2 is gradually cooled and solidified from the lowermost portion by contact with the lower mold body 3 </ b> B to become an ingot 21. The ingot 21 is gradually pulled out below the upper mold 2 as the lower mold 3 is lowered, and is cooled by the cooling water 14 a discharged from the upper mold 2. At this time, since the molten metal 13 and the ingot 21 immediately after solidification are soft and held by surface tension, even if drawn out below the refractory material 4, it spreads outward and contacts the lower part of the inner wall surface of the upper mold 2. There is nothing. Further, since the cooling effect is not suddenly weakened by not contacting the inner wall surface of the upper mold 2, the solidified ingot 21 is not remelted by the heat of the molten metal 13. Further, the ingot surface does not become rough due to friction between the upper mold 2 and the ingot 21. Therefore, a billet having excellent surface properties can be cast without roughening the surface.

Experimental example [1]
α = 66 °, W ₁ = 3 mm, W ₂ = 40 mm, a continuous casting apparatus using the refractory material 4 made of calcium silicate was manufactured, and the continuous casting of the aluminum alloy having the composition shown in Table 1 was represented by this casting apparatus. The casting conditions shown in Fig. 2 were carried out without lubrication.

  A photograph of the cast billet surface is shown in FIG. As comparative examples, photographs of billet surfaces obtained by float casting and hot top casting of an aluminum alloy having the composition shown in Table 1 using a conventional apparatus are shown in FIGS. 4 and 5, respectively. Casting by conventional equipment was performed while refueling. As is clear from these photographs, according to the continuous casting apparatus 1 according to the present invention, a billet having excellent surface properties compared to the billet cast by the conventional apparatus could be manufactured even without oil supply.

Experimental example [2]
Test number 1 α = 90 °, W ₁ = 3 mm, W ₂ = 40 mm
Test number 2 α = 66 °, W ₁ = 1 mm , W ₂ = 40 mm
Test number 3 α = 66 °, W ₁ = 3 mm, W ₂ = 85 mm
Three continuous casting apparatuses with test numbers 1 to 3 deviating from the conditions of the present invention were prepared, and aluminum alloys having the compositions shown in Table 1 were cast under the casting conditions shown in Table 2. Surface photographs of the obtained billet are shown in FIGS. The underlined part is a condition deviating from the condition of the present invention.

  The billets manufactured by Test Nos. 1, 2, and 3 all have irregularities on the surface, and in Experimental Example 1, the irregularities appear and are rougher than the billet cast as the present invention (FIG. 3). Recognize. There is also evidence of redissolution.

Next, an aluminum alloy material that is preferably cast by the vertical continuous casting apparatus 1 according to the present invention and each element contained therein will be described.
As an aluminum alloy material suitable for the vertical continuous casting apparatus 1, a material containing 0.2% by mass or more of any one or more of Pb, Sn, and Bi is preferable (Claim 6). Pb, Sn, and Bi are known as elements that improve the chip breaking property of the aluminum alloy. When these elements are added to the aluminum alloy, they form a low melting point compound. This low-melting-point compound serves as a starting point for chip breaking during cutting and exhibits an effect of improving chip breaking. However, if the added amount exceeds 0.2% by mass, these elements ooze out to the surface, and casting becomes difficult by the conventional casting method. On the other hand, in the casting method of the present invention, since the solidified ingot can be cast without substantially contacting the inner wall surface of the upper mold, an ingot having a good surface property can be cast. In addition, even if it adds exceeding 2 mass%, since the improvement of chip parting property cannot be expected beyond it, it is preferable to make it 2 mass% or less.

  Moreover, it is preferable to set it as about 5.0-6.5 mass% as Cu of such an aluminum alloy material (Claim 7).

  Cu is a material that increases the mechanical strength of an aluminum alloy, and its effect is low when it is 5.0% by mass or less, and when it exceeds 6.5% by mass, the plastic workability is lowered, and extrusion, rolling, forging, Plastic processing such as drawing becomes difficult. Moreover, the hard intermetallic compound used as the starting point of chip parting is also formed, and it contributes to the improvement of chip parting property.

  Si and Fe are inevitably mixed in the aluminum alloy. Such inevitable impurities, Si and Fe, have an effect of improving the strength of the aluminum alloy. Si is a material that improves the castability of an aluminum alloy, but if it exceeds 2% by mass, the coexisting temperature range of the solid phase and the liquid phase becomes narrow, and metal leakage due to remelting tends to occur. It is preferable to restrict the amount to mass%. Since Fe forms a coarse intermetallic compound when the content increases, it causes a decrease in the elongation of the cast material. Therefore, Fe is preferably regulated to 1.0% by mass or less.

  As other aluminum alloys, Si is 2 to 4% by mass, Cu is 0.2 to 0.8% by mass, Mg is 0.4 to 1.6% by mass, and Cr is 0.05 to 0.6%. It is preferable to use an aluminum alloy containing 0.02 to 0.25% by mass of Ti and 0.02 to 0.25% by mass of the Ti, with the remainder being aluminum and inevitable impurities.

  Si improves the mechanical strength of the aluminum alloy and forms a hard intermetallic compound. This intermetallic compound serves as a base point for cutting chips during cutting, and improves chip cutting properties. This effect becomes prominent with addition of 2% by mass or more, but when it exceeds 2% by mass, the coexisting temperature range of the solid phase and the liquid phase becomes narrow, so that metal leakage due to remelting is likely to occur in the conventional casting method. Become. On the other hand, in the casting method of the present invention, since the solidified ingot can be cast without substantially contacting the inner wall surface of the upper mold, an ingot having a good surface property can be cast. If it exceeds 4% by mass, the amount of hard intermetallic compounds increases and wear of the cutting tool is accelerated. For this reason, it is preferable that Si exists in the range of 2-4 mass%.

  Cu exhibits the effect of improving the mechanical strength of the aluminum alloy. This effect becomes remarkable when 0.2% by mass or more is added, and when it exceeds 0.5% by mass, the corrosion resistance decreases. For this reason, it is preferable to set it as 0.2-0.8 mass% in consideration of mechanical strength and corrosion resistance.

  Mg exhibits the effect of improving the mechanical strength of the aluminum alloy. This effect becomes remarkable when 0.4% by mass or more is added. On the other hand, when it exceeds 1.6 mass%, plastic workability will worsen and plastic processing, such as extrusion, rolling, forging, and drawing, will become difficult. For this reason, it is preferable to set it as 0.4-1.6 mass% considering mechanical strength and plastic workability, such as extrusion, rolling, forging, and drawing.

  Cr exhibits an effect of refining crystal grains. In addition, it exhibits the effect of suppressing the coarsening of recrystallization during heat treatment. This effect becomes remarkable when 0.05% by mass or more is added. Even if 0.6% by mass or more is added, no further improvement in action can be expected, so Cr is preferably regulated to 0.05 to 0.6% by mass or less.

  Ti is a material that is often added as a refining material of crystal grains of an aluminum alloy, and exhibits an effect of suppressing casting cracks. It also has the effect of improving corrosion resistance. This effect becomes significant when 0.02% by mass or more is added. Even if it is added in excess of 0.25% by mass, no further improvement in the effect can be expected. Therefore, it is preferable to regulate the content within the range of 0.02 to 0.25% by mass.

  B is a material added as a grain refiner together with Ti, but if added over 0.005% by mass, the fluidity of the aluminum alloy is reduced and castability is deteriorated. It is preferable to regulate to not more than mass%.

  Fe is an impurity that is inevitably mixed in, but exhibits the effect of improving the mechanical strength and forming a hard intermetallic compound, thereby improving the chip breaking property. However, if the content exceeds 1.0% by mass, the intermetallic compound becomes coarse and the elongation is lowered. Therefore, the content is preferably regulated to 1.0% by mass or less.

FIG. 9 is a sectional view showing another embodiment of the present invention.
In this embodiment, instead of providing a cooling water outlet at the bottom of the upper mold 2, a pipe 30 for the cooling water 14 is provided below the upper mold 2 so as to oppose the ingot 21, and its opening The cooling water 14 is sprayed onto the surface of the ingot 21 by using the discharge port 31 as a cooling outlet.
Even in such a structure, the same effect as the above-described embodiment was obtained.

1 is a cross-sectional view showing an embodiment of an aluminum vertical casting apparatus according to the present invention. It is an expanded sectional view for demonstrating the principal part of the mold apparatus. It is a surface photograph of a billet. It is a surface photograph of a billet. It is a surface photograph of a billet. It is a surface photograph of a billet. It is a surface photograph of a billet. It is a surface photograph of a billet. It is sectional drawing which shows other embodiment of the vertical vertical casting apparatus of the aluminum which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vertical type continuous casting apparatus, 2 ... Upper mold, 3 ... Lower mold, 4 ... Refractory material, 13 ... Molten metal, 11 ... Casting space, 12 ... Hollow part, 14, 14a ... Cooling water, 16 ... Discharge port, 21: Ingot, 23: Tapered surface, α: Inclination angle.

Claims (8)

A casting space into which molten metal is introduced and a hollow portion through which cooling water passes are formed, and a discharge port for injecting the cooling water in the hollow portion obliquely downward and inward is formed at the bottom, and the casting space An upper mold that forcibly cools the molten metal from its surroundings,
A hollow refractory material inserted from above into the casting space of this upper mold or installed at the top,
A vertical continuous casting apparatus including a lower mold and a lower mold that continuously draws an ingot that solidifies in the upper mold by being lowered at the lower part of the upper mold. In
The lower end opening side of the refractory material is substantially similar to the shape of the ingot and forms a tapered surface whose diameter increases downward on the inner peripheral surface. The inclination angle of the tapered surface is 45 ° to 80 °. The horizontal distance from the inner wall surface of the upper mold to the lower end of the tapered surface is 2 to 50 mm, and from the height position where the cooling water sprayed from the discharge port is applied to the ingot to the lower surface of the refractory material An aluminum vertical casting apparatus characterized in that the vertical distance is set to 5 to 80 mm.   2. An aluminum vertical casting apparatus according to claim 1, wherein a cooling water discharge port is provided below the upper die instead of providing a cooling water discharge port at the bottom of the upper die.   The aluminum vertical casting apparatus according to claim 1 or 2, wherein the refractory material has a thermal conductivity of 50 W / m · K or less.   The refractory material contains one or more of calcium silicate, fiber ceramics, alumina / silica mold material, and fused silica as a main component. An aluminum vertical casting apparatus as described in 1. A method of continuously casting aluminum or an aluminum alloy using the vertical continuous casting apparatus according to any one of claims 1 to 4,
A vertical continuous casting method characterized in that aluminum or an aluminum alloy is cast at a constant lower mold lowering speed set to 20 to 500 mm / min. A method for continuously casting an aluminum alloy using the vertical continuous casting apparatus according to any one of claims 1 to 4,
A vertical casting method characterized by casting an aluminum alloy containing 0.2% by mass or more of any one or more of Pb, Sn, and Bi. A method for continuously casting an aluminum alloy using the vertical continuous casting apparatus according to any one of claims 1 to 4,
Casting an aluminum alloy containing 5.0 to 6.5% by mass of Cu, 0.2% by mass or more of any one or more of Pb, Sn, and Bi, with the balance being aluminum and inevitable impurities. A vertical continuous casting method characterized. A method for continuously casting an aluminum alloy using the vertical continuous casting apparatus according to any one of claims 1 to 4,
2-4% by mass of Si, 0.2-0.8% by mass of Cu, 0.4-1.6% by mass of Mg, 0.05-0.6% by mass of Cr, 0.02-0.0% of Ti A vertical continuous casting method characterized by casting an aluminum alloy containing 0.25% by mass and the balance being aluminum and inevitable impurities.