Patent Application
20200122227
The present invention relates to a continuous casting apparatus for metal and a continuous casting method for metal each for producing a continuously cast material, such as, e.g., aluminum.
Note that in this specification and claims, unless otherwise specified, the term “aluminum (Al)” is used to include the meaning of an aluminum alloy (Al alloy), and the term “continuous casting” is used to include the meaning of semi-continuous casting.
Aluminum materials which become the base of various aluminum products are most commonly produced by die casting. On the other hand, for products requiring high quality and high strength while having less variation, forged products (forged materials) are often used.
A forging material subjected to a forging process is often produced based on a continuously cast material obtained with continuous casting.
For example, as described in Patent Document 1 listed below, in a vertical type continuous casting apparatus, it is configured as follows. The casting direction is vertically downward, a molten metal is passed through a mold, and a surface of an ingot is solidified. Cooling water as a cooling medium (refrigerant) is ejected to the ingot from the entire periphery of the ingot right under the mold to rapidly cool down the entire ingot. In aluminum continuous casting, cooling of an ingot is a very important step, and for example, when the cooling performance is sufficient, the ingot is rapidly solidified even to the inside thereof, so that the ingot structure can be controlled in an excellent state.
In a conventional continuous casting apparatus as shown in Patent Document 1, a method of ejecting cooling water for cooling an ingot is generally configured such that cooling water is ejected toward the outer peripheral surface of the ingot from slit-like or hole-like ejection ports provided right under the mold so as to correspond to the outer periphery of the ingot.
However, in a cooling water ejection method for the aforementioned conventional continuous casting apparatus, some of the ejection ports may sometimes be clogged due to the deterioration, etc., of the mold and/or the water supply pipe. In that case, the cooling water is not evenly ejected to the entire periphery of the ingot, resulting in uneven cooling, which causes a portion to which the cooling water does not hit. As a result, the portion and the vicinity thereof become a high temperature to cause a portion in which the cooling is insufficient (insufficiently cooled portion). In addition, even if the ejected cooling water flows down on the ingot surface and is supplied to the insufficiently cooled portion, since the portion is at a high temperature, a boiling film phenomenon occurs to lower the heat transfer coefficient, resulting in insufficient cooling, so that the high temperature status is maintained. In this way, the insufficiently cooled portion is continuously maintained in a high temperature state, causing material segregation and stress concentration. Thus, there is a problem that the quality may be deteriorated due to ingot cracking and the like.
have been made in view of the above-mentioned and/or other problems in the related art. The preferred embodiments of the present invention can significantly improve upon existing methods and/or apparatuses.
The present invention has been made in view of the aforementioned problems and aims to provide a continuous casting apparatus for metal and a continuous casting method for metal each having sufficient cooling performance and capable of producing a high quality continuously cast material.
The other purposes and advantages of the present invention will be made apparent from the following preferred embodiments.
In order to solve the aforementioned problems, the present invention is equipped with the following means.
[1] A continuous casting apparatus for metal, comprising:
a mold through which an ingot is continuously passed to be solidified; and
at least one ejection port arranged on an outer side of an outer periphery of the ingot passed through the mold and configured to eject a refrigerant to cool the ingot,
[2] The continuous casting apparatus for metal as recited in the aforementioned Item [1],
wherein the at least one ejection port includes a plurality of ejection ports arranged at predetermined intervals along the outer periphery of the ingot, and
wherein when an angle at which the ejection direction of the refrigerant is inclined with reference to the projection reference axis is denoted as an ejection angle, all the ejection angles of the refrigerants ejected from the plurality of ejection ports are set to be equal.
[3] The continuous casting apparatus for metal as recited in the aforementioned Item [1],
wherein the at least one ejection port includes a plurality of ejection ports arranged at predetermined intervals along the outer periphery of the ingot, and
wherein when an angle at which the ejection direction of the refrigerant with reference to the projection reference axis is inclined is denoted as an ejection angle, the ejection angles of the refrigerants ejected from the plurality of ejection ports include at least two or more different ejection angles.
[4] The continuous casting apparatus for metal as recited in any one of the aforementioned Items [1] to [3], wherein the metal is aluminum.
[5] The continuous casting apparatus for metal as recited in any one of the aforementioned Items [1] to [4], wherein the refrigerant is cooling water.
[6] The continuous casting apparatus for metal as recited in any one of the aforementioned Items [1] to [5], wherein the continuous casting apparatus is a vertical type continuous casting apparatus configured such that a casting direction is in a vertically downward direction.
[7] The continuous casting apparatus for metal as recited in any one of the aforementioned Items [1] to [5], wherein the continuous casting apparatus is a horizontal continuous casting apparatus configured such that a casting direction is a horizontal direction.
[8] A continuous casting method for metal, comprising:
continuously casting an ingot with a mold; and
ejecting a refrigerant from an ejection port arranged on outer periphery of the ingot passed through the mold to cool the ingot,
wherein when an axis connecting the ejection port and an axis of the ingot is denoted as a projection reference axis as viewed in a direction of an axis of the ingot, the ejection port is configured such that an ejection direction of the refrigerant ejected from the ejection port is inclined in one direction with reference to the projection reference axis so that the ejection direction of the refrigerant does not intersect with the axis of the ingot.
According to the continuous casting apparatus for metal as recited in the aforementioned Item [1], since the ejection direction of the refrigerant ejected from the ejection port is inclined in one direction so as to not intersect with the axis of the ingot, the refrigerant is not ejected at a right angle to the outer peripheral surface of the ingot but is ejected obliquely. Therefore, the refrigerant sprayed onto the outer peripheral surface of the ingot improves the adhesiveness with the ingot, and as the refrigerant flows down in a spiral manner around the entire periphery of the ingot without interruption, the entire periphery of the ingot is evenly cooled. Therefore, the ingot is evenly cooled and sufficient cooling performance can be obtained without occurrence of partially insufficient cooling. As a result, partial high temperature abnormality of the ingot can be assuredly prevented, and defects, such as, e.g., ingot cracking, due to the partial high temperature abnormality can be prevented, which in turn can reduce the occurrence of quality defects, so that a high quality continuously cast material can be produced.
According to the continuous casting apparatus for metal as recited in the aforementioned Items [2] to [7], the aforementioned effects can be more assuredly obtained.
According to the continuous casting method for metal as recited in the aforementioned Item [8], similarly to the aforementioned device, since the refrigerant is sprayed not at a right angle to the outer peripheral surface of the ingot but is sprayed obliquely, the entire peripheral region of the ingot is uniformly cooled without unevenness and sufficient cooling performance can be obtained. As a result, the occurrence of quality defects can be reduced, so that a high quality continuously cast material can be produced.
Some preferred embodiments of the present invention are shown by way of example, and not limitation, in the accompanying figures.
In the following paragraphs, some preferred embodiments of the present invention will be described by way of example and not limitation. It should be understood based on this disclosure that various other modifications can be made by those in the art based on these illustrated embodiments.
As shown in the figure, the casting apparatus is equipped with a mold 2 for casting an ingot W2 by solidifying the aluminum molten metal W1, and a molten metal receiving tank 3 provided on the upper side of the mold 2 and configured to eject the molten metal W1 into the mold 2.
The mold 2 is cooled by cooling water M as primary cooling water supplied to the inside of the mold 2. Further, at the lower end portion of the mold 2, a plurality of ejection ports 1 for ejecting the cooling water M as secondary cooling water in the mold 2 is provided at predetermined intervals in the circumferential direction, as described later.
In this casting apparatus, the aluminum molten metal W1 as a metal supplied in the molten metal receiving tank 3 is ejected on the inner side of the cooled mold 2. The ejected molten metal W1 is primarily cooled by coming into contact with the mold 2 and becomes a semi-solidified ingot W2. The ingot W2 in a semi-solidified state is in a state in which a solidified film is formed on the outer periphery. Then, the ingot W2 in that state continuously passes through the inner side the mold 2 in a downward direction, and the cooling water M is ejected from the ejection ports 1 of the mold 2 onto the ingot W2 immediately after passing through the mold 2, thereby cooling the ingot W2 by direct contact of the cooling water M to the outer peripheral surface of the ingot W2. In this way, the ingot W2 is subjected to the secondary cooling while being drawn downward, so that a large portion is solidified. Thus, a round-rod shaped continuously cast material (billet) is produced.
Next, the cooling method of the ingot W2 in the casting apparatus of this embodiment will be explained in detail.
As shown in
Further, in the casting apparatus of the first embodiment, when the angle at which the ejection direction D of the cooling water M is inclined with reference to the projection reference axis B is denoted as an ejection angle θ, all the ejection angles θ of the cooling water M ejected from the ejection ports 1 are set to be equal.
Furthermore, in this embodiment, toward the paper surface of
As described above, in the casting apparatus of this first embodiment, in a state in which it is viewed from the lower side, since the ejection direction D of the cooling water M ejected from the ejection port 1 of the mold 2 is inclined in one direction so as to not intersect with the axis X of the ingot W2 (mold 2), the cooling water M is sprayed not at a right angle onto the outer peripheral surface of the ingot W2, but is sprayed obliquely with reference to the outer peripheral surface of the ingot W2. Therefore, the cooling water M ejected from each ejection port 1 flows down in a spiral manner along the outer peripheral surface of the ingot W2.
That is, by ejecting the cooling water M obliquely to the outer peripheral surface of the ingot W2, the wettability (adhesiveness) between the cooling water M and the ingot W2 is improved, and at the same time, the surface tension and the Coanda effect on the cooling water M to the ingot W2 increase. As a result, the cooling water M flows down along the entire periphery of the ingot W2 in a spiral manner without interruption, and the entire periphery of the ingot W2 is evenly and uniformly cooled by the secondary cooling water M.
Therefore, the entire region of the ingot W2 is evenly cooled without causing partially insufficient cooling, so sufficient cooling performance can be obtained. In addition, since the cooling water M flows down along the outer peripheral surface of the ingot W2 in a spiral manner, the contact length (flow down path) of the cooling water M with respect to the ingot W2 becomes longer, so the contact time between the cooling water M and the ingot W2 also becomes longer, thereby further improving the cooling performance. As a result, the occurrence of the partial high temperature abnormalities in the ingot W2 can be reliably prevented, partial high temperature which becomes the cause of material segregation and stress concentration can be eliminated, defects such as ingot cracking can be prevented, and the occurrence of the quality defect can be significantly reduced. Thus, a continuously cast material as a high quality ingot W2 can be produced.
Here, in the casting apparatus of this embodiment, there are some cases where some of the ejection ports 1 are clogged due to some causes, such as, e.g., the deterioration of the mold and the deterioration of the water supply pipe. However, even in such a case, the entire periphery of the ingot W2 can be evenly cooled. That is, since the cooling water M is ejected obliquely with reference to the outer periphery of the ingot W2, in comparison with the conventional case where the cooling water W is ejected at a right angle with reference to the outer peripheral surface of the ingot W2, the ejection range of the cooling water M ejected from the ejection port 1 to the ingot W2 becomes wider with respect to the outer peripheral surface of the ingot.
Therefore, even in cases where the cooling water M is not ejected from some of the ejection ports 1, the cooling water M2 can be ejected to the entire periphery of the ingot W2 without interruption. Further, as described above, since the ejected cooling water M flows down along the outer peripheral surface of the ingot W2 in a spiral manner, the entire peripheral region of the ingot W2 can be cooled evenly. As described above, even in cases where some of the ejection ports 1 are clogged, the cooling water M is ejected so as to supplement the clogged portions, thereby allowing for even cooling of the entire peripheral region of the ingot W2, which can secure the sufficient cooling performance. This in turn enables assured reduction of the occurrence of defects, and assured production of a high quality continuously cast material.
As described above, according to the hot-top casting apparatus of the first embodiment, since the ejection direction D of the cooling water M ejected from the ejection port 1 of the mold 2 is inclined, the entire periphery of the ingot W2 can be evenly cooled, and sufficient cooling performance can be obtained, so that a high quality continuously cast material can be produced.
Furthermore, in this embodiment, in order to allow the cooling water M to flow down so as to spiral around the outer peripheral surface of the ingot W2 and to evenly cool the entire periphery, it is preferable that the ejection angle θ of the cooling water M be set to 3° to 45°, and more preferably 5° to 20°.
As shown in the figure, in this casting apparatus, when viewed from the bottom along the axis X of the ingot W2, the ejection angle θ of the cooling water M ejected from each ejection direction D of the plurality of ejection ports 1 provided on the lower inner peripheral surface of the mold 2 is inclined in one direction, but each ejection angle θ is different. In this embodiment, each ejection angle θ of the cooling water M is randomly set especially in terms of the regularity.
Since the other configurations of the casting apparatus of the second embodiment are substantially the same as those of the casting apparatus of the first embodiment, the same or corresponding portions are allotted by the same reference symbols and the redundant descriptions will be omitted.
In the casting apparatus of the second embodiment, similarly to the aforementioned first embodiment, since the ejection direction D of the cooling water M is inclined, the cooling water M is ejected obliquely with reference to the outer peripheral surface of the ingot W2 and flows down in a spiral manner along the outer peripheral surface of the ingot W2. Therefore, in the same manner as in the aforementioned first embodiment, the entire periphery of the ingot W2 can be evenly cooled, and sufficient cooling performance can be obtained, so that a high quality continuously cast material can be produced.
Furthermore, since the ejection angles θ of the cooling water M ejected from the ejection ports 1 are set to be different, the adhesion amount of the cooling water M flowing down along the outer peripheral surface of the ingot W2 in a spiral manner varies appropriately depending on the peripheral position. As a result, the cooling water M is more easily adhered to the outer peripheral surface of the ingot W2, enabling a longer contact time between the cooling water M and the ingot W2, which in turn can further improve the cooling performance, so that a high quality continuously cast material can be more assuredly produced.
In addition, in the aforementioned embodiment, all of the ejection directions D of the cooling water M from the ejection ports 1 are inclined with reference to the respective projection reference axes B, but the present invention is not limited to that. In the present invention, ejection directions D of some of the cooling water M among the ejection directions D of the cooling water M ejected from the ejection ports 1 may be matched with reference to the projection reference axis B. In other words, in the present invention, among the ejection directions D of the cooling water M ejected from the respective ejection ports 1, it is enough that at least one ejection direction D of the cooling water M is inclined with reference to the projection reference axis B.
Further, like the aforementioned second embodiment, in cases where the respective ejection directions D of the cooling water M are made different, it is not necessary to make all ejection angles θ of the cooling water M different, but may be configured such that only some of the ejection angles θ are made different and the remaining ejection angles θ are made equal. In other words, in the present invention, it is sufficient that at least two or more different ejection angles θ are included among all of the ejection angles θ.
Further, in the aforementioned embodiment, an example is described in which the present invention is applied to a hot-top casting apparatus as a vertical type continuous casting apparatus in which the casting direction is set vertically downward. However, the present invention is not limited to that and may be applied to a horizontal type (lateral type) continuous casting apparatus in which the casting direction is set in a horizontal direction. In this case, the state viewed along the axis of the ingot corresponds to the state of the cross-sectional view orthogonal to the axis of the ingot.
Also, in the aforementioned embodiment, the description is made by exemplifying an example in which cooling water, etc., is used as a refrigerant. However, the present invention is not limited to that, and a liquid phase refrigerant other than water may be used. Furthermore, in the present invention, it is not limited to a liquid phase refrigerant, but a gas phase refrigerant constituted by a gas or the like having a surface tension lower than a liquid phase refrigerant, or a solid refrigerant such as a powder and the like having less interaction with the ingot compared with the liquid phase refrigerant, may be used.
In addition, in the present invention, a suitable additive may be mixed into the refrigerant if necessary, or a mixed refrigerant in which a plurality of refrigerants is mixed may be used as the refrigerant.
As shown in the casting apparatus of the first embodiment as shown in
Further, an aluminum molten metal W1 adjusted so as to include Si: 11 mass %, Cu: 2.5 mass %, Mg: 0.4 mass %, and the balance being pure aluminum, and unavoidable additive elements was supplied to the mold 2 of the casting apparatus of the aforementioned Example, and while continuously forming an aluminum ingot W2 in a semi-solidified state in which the molten metal W1 was solidified by the mold 2, the cooling water M ejected from the ejection ports 1 was sprayed to cool the ingot W2 to cast a round-rod shaped billet (continuously cast material) having a diameter φ of 107 mm and a length of 5,500 mm.
Note that, in this casting process, the casting speed was 190 mm/min, the casting temperature was 710° C., the water temperature of the cooling water M is 15° C., and the amount of water per a single ingot was 45 L/min.
Under the aforementioned casting conditions, 240 pieces of billets (continuously cast material) were cast and the good product rate was measured. That is, in the cast billet, when the solidified phase is partially thinned due to partial insufficient cooling, the solidified film in the thin portion may break and the molten metal inside may leak out. The leak phenomenon is generally referred to as a molten metal leak, and since the vicinity of the leak portion in the ingot (cast material) causes structure abnormality and becomes different in solidified shape, there is a high possibility of becoming a defective product. Therefore, in the Example and the following Comparative Examples, a cast material with no molten metal leak is denoted as a good product, a cast material with a molten metal leak is denoted as a defective product, and the rate (%) of good productions to the total number of cast materials was measured as a good product rate. The results are shown in Table 1.
In addition, when the degree of the molten metal leak is large, in some cases, the entire ingot may melt and become impossible to be cast.
As shown in
Then, 45 pieces of similar billets (cast materials) were manufactured under similar casting conditions as in the aforementioned Example and the good product rate was similarly measured. The results are shown in Table 1.
As it is apparent from Table 1, the cast materials produced by the casting apparatus of the Example according to the present invention did not show any molten metal leaks and the good product rate was 100%. Thus, the casting apparatus of the Example has sufficient cooling performance and can produce high quality cast products.
On the other hand, in the cast materials produced by the casting apparatus in Comparative Examples which deviate from the gist of the present invention, two cast materials out of 45 pieces of cast materials produced had molten metal leaks, and the good product rate was 95.6%. Accordingly, the casting apparatus of Comparative Example is slightly inferior in cooling performance compared with the casting apparatus in the Example, and is slightly difficult to maintain high quality.
The continuous casting apparatus for metal of the present invention can be suitably used for producing a continuously cast material used as a material for an extruded material, a rolled material, a forged material, etc., of metal such as aluminum.
The present application claims priority to Japanese Patent Application No. 2018-197482 filed on Oct. 19, 2018, the entire disclosure of which is incorporated herein by reference in its entirety.
It should be understood that the terms and expressions used herein are used for explanation and have no intention to be used to construe in a limited manner, do not eliminate any equivalents of features shown and mentioned herein, and allow various modifications falling within the claimed scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-197482 | Oct 2018 | JP | national |
