JP2014018823A - Method for producing semi-solidified metal slurry, molten metal holding container, and semi-solidified metal slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing semi-solidified metal slurry, which can uniformalize the structure and temperature of the semi-solidified metal slurry structure.SOLUTION: A method for producing semi-solidified metal slurry, in which a solid phase and a liquid phase coexist, includes an agitation step of agitating molten metal Y in a molten metal holding container 10 in a noncontact manner. The molten metal holding container 10 has a bottom part 11, a cylindrical exterior wall part 12 erected on the bottom part 11, and a columnar inner wall part 13 erected on the inside with respect to the exterior wall part 12 on the bottom part 11. In the agitation step, the molten metal is convected between the exterior and interior wall parts 12 and 13.

Description

The present invention relates to a method for producing a semi-solid metal slurry, a molten metal holding container, and a semi-solid metal slurry.

  Semi-solid forging is known as a forging method for aluminum alloys, magnesium alloys and the like. In semi-solid forging, after producing a semi-solid metal slurry in which a solid phase and a liquid phase coexist, the semi-solid metal slurry is put into a mold and then molded. In the method for producing a semi-solid metal slurry, for example, a molten metal melted in a holding furnace is poured with a ladle or the like and poured into a molten metal holding container, and the molten metal is electromagnetically stirred in the molten metal holding container. A stirring step and a standing step for standing for a predetermined time are performed. Since the solid phase and the liquid phase coexist, the semi-solid metal slurry can be pressed with a relatively small force when pressed with a mold. Thereby, the burden on a shaping | molding die can be made small. In addition, semi-solid forging can suppress the entrainment of air when materials are poured into the mold, compared to gravity casting and low pressure casting, where molten metal is poured directly into the mold. There is an advantage that it is difficult to occur.

  FIG. 8A is a cross-sectional view showing a conventional molten metal holding container, FIG. 8B is a view showing a temperature distribution of the molten metal after a conventional standing step, and FIG. It is a figure at the time of throwing the solidified metal slurry into a shaping | molding die.

  As shown to (a) of FIG. 8, the conventional molten metal holding | maintenance container 100 is a container which exhibited the bottomed cylinder shape and opened upwards. The molten metal Y is stored in the molten metal holding container 100. In the stirring step, a magnetic field generator 101 is installed around the molten metal holding container 100, and the molten metal Y is stirred by the magnetic field generated from the magnetic field generator 101 (see Patent Document 1). In the conventional stirring process, as shown by the arrow in FIG. 8A, the molten metal Y is circulated in the order of the wall surface 100a side → the bottom surface 100b side → the central portion 100c → the wall surface 100a side of the molten metal holding container 100. It has become.

JP 2009-148771 A

  Here, for example, an aluminum alloy containing aluminum, magnesium, silicon or the like is known to exhibit higher strength and toughness as the solidification structure becomes finer and uniform. Since the resinous crystal branches crystallized on the wall surface 100 a are divided by the stirring step described above, the primary crystal α-Al circulates in the molten metal holding vessel 100. At this time, since the central portion 100c of the molten metal holding container 100 is far from the wall surface 100a, the molten metal Y has a relatively high temperature. Therefore, in the conventional molten metal holding container 100, since the circulating primary crystal α-Al becomes a liquid phase again at the central portion 100c, the number of primary crystal α-Al produced tends to decrease. Thereby, since the mixing balance of aluminum, magnesium, silicon and the like is deteriorated, an aluminum-rich phase is easily generated, and there is a problem that the strength and toughness of the molded product are lowered.

  Further, as shown in FIG. 8B, when the temperature distribution of the molten metal Y after the standing step is viewed, the vicinity of the wall surface 100a and the bottom surface 100b is low temperature, but the central portion 100c is high temperature. As a result, the vicinity of the central portion 100c remains in the liquid phase even after the standing step, and therefore, when the produced semi-solid metal slurry is put into the mold, the liquid phase portion oozes out into the mold. This oozing liquid phase solidifies upon contact with the mold, causing the generation of a Si segregation layer.

  Further, as shown in FIG. 8 (c), when the conventional semi-solid metal slurry 110 is put into the mold 120, the molten metal holding container 100 is inverted and the mold is caused by the weight of the semi-solid metal slurry 110. 120. However, it is not easy to accurately position the semi-solid metal slurry 110 with respect to the mold 120.

  The semi-solid metal slurry 110 is weak in strength because the central portion 100c is in a liquid phase, and when it is put into the mold 120, the shape of the semi-solid metal slurry 110 is irregularly collapsed due to an impact at the time of charging. Once the shape of the semi-solid metal slurry 110 is collapsed, it becomes difficult to move the semi-solid metal slurry 110 with respect to the mold 120, so that it is difficult to correct the positioning of the semi-solid metal slurry 110 with respect to the mold 120. In addition, if the shape of the semi-solid metal slurry 110 is collapsed, the filling into the forming die 120 becomes nonuniform and the forming accuracy is lowered. On the other hand, if the standing time in the standing step is lengthened, the molten metal Y is hardened by the temperature drop and the strength of the slurry itself is increased, but the liquid phase is not present by hardening, so the semi-solid metal slurry It will disappear.

  The present invention was created in view of the above-described circumstances, and provides a method for producing a semi-solid metal slurry and a molten metal holding container capable of achieving uniform structure and temperature of the semi-solid metal slurry. Let it be an issue. It is another object of the present invention to provide a semi-solid metal slurry that can be easily positioned with respect to a mold.

  In order to solve the above problems, the present invention is a method for producing a semi-solid metal slurry in which a solid phase and a liquid phase coexist, and includes a stirring step of stirring the molten metal in a molten metal holding container in a non-contact manner. The molten metal holding container has a bottom portion, a cylindrical outer wall portion standing on the bottom portion, and a columnar inner wall portion standing on the inner side of the outer wall portion at the bottom portion, and in the stirring step, The molten metal is convected between the outer wall portion and the inner wall portion.

  According to this configuration, since the columnar inner wall portion is formed in the molten metal holding container, primary crystal α-Al is formed by the outer wall portion and the inner wall portion. That is, since the contact area between the molten metal holding container and the molten metal is larger than that of the conventional container, a large amount of primary α-Al can be generated. Moreover, it can avoid that the center part of a molten metal becomes high temperature compared with the conventional container by forming an inner wall part. Moreover, since the primary crystal α-Al circulated by convection passes through not only the outer wall portion but also the vicinity of the inner wall portion, remelting of the primary crystal α-Al can be prevented. Thereby, the structure | tissue and temperature of the semi-solid metal slurry manufactured can be equalized.

  Moreover, it is preferable that the molten metal holding container is a non-magnetic material, and electromagnetic stirring is performed in the stirring step. According to this configuration, the molten metal can be stirred without contact.

  Further, the present invention is a method for producing a semi-solid metal slurry in which a solid phase and a liquid phase coexist, including a standing step of standing the molten metal in a molten metal holding container, wherein the molten metal holding container is A cylindrical outer wall portion standing on the bottom portion, and a columnar inner wall portion standing on the inner side of the outer wall portion at the bottom portion, and in the stationary step, the inner wall portion is melted The molten metal is cooled by contact with the metal.

  According to such a configuration, since the molten metal is cooled at the inner wall portion, it is possible to avoid the central portion of the molten metal holding container from becoming hot as compared with the conventional container. Thereby, the structure and temperature of the manufactured semi-solid metal slurry can be made uniform.

  Moreover, it is preferable that the said inner wall part is formed with the hollow part, and includes the cooling process which flows the fluid through the said hollow part and cools the said molten metal. According to such a configuration, the cooling process of the molten metal can be easily performed, and the cooling temperature can be adjusted.

  The present invention also includes a bottom, a cylindrical outer wall standing upright at the bottom, and a columnar inner wall standing up inside the outer wall at the bottom, and the outer wall and the inner wall The molten metal is cooled by the molten metal coming into contact with the outer wall portion and the inner wall portion while holding the molten metal therebetween.

  According to such a configuration, since the molten metal is cooled at the inner wall portion, it is possible to avoid the central portion of the molten metal holding container from becoming hot as compared with the conventional container. Thereby, the temperature of the manufactured semi-solid metal slurry can be made uniform. Moreover, a cylindrical inner side surface is formed inside the produced semi-solid metal slurry by the inner wall portion. Thereby, the intensity | strength of the manufactured semi-solidified metal slurry can be raised.

  Moreover, it is preferable that the said columnar inner wall part is formed in the hollow cylinder shape opened in the said bottom part at least. According to such a configuration, for example, if a fluid is passed through the hollow portion of the inner wall portion, the molten metal can be efficiently cooled.

  Moreover, it is preferable that the said inner wall part is extended more than the height of the said outer wall part. According to this structure, since the cylindrical inner surface is formed over the entire height direction of the manufactured semi-solid metal slurry, the strength of the semi-solid metal slurry can be further increased.

  Moreover, it is preferable that the said inner wall part is tapering off toward the front-end | tip. According to this configuration, the semi-solid metal slurry can be easily detached when the semi-solid metal slurry is charged into the mold.

  Further, the present invention is a semi-solid metal slurry in which a solid phase and a liquid phase coexist, a bottom surface, a cylindrical outer surface standing on the bottom surface, and a ceiling that is continuous with the outer surface and faces the bottom surface. A cylindrical inner side surface standing on the inner side of the outer side surface at the bottom surface, and a hollow portion formed inside the inner side surface, the bottom surface, the outer side surface, the ceiling The surface and the inner surface are formed to be harder than the inner molten metal.

  According to this configuration, the cylindrical inner surface is formed inside, and the bottom surface, the outer surface, the top surface, and the inner surface are formed harder than the inner molten metal. Strength can be increased. Thereby, since the shape of a semi-solid metal slurry becomes difficult to collapse when thrown into a shaping | molding die, the positioning with respect to a shaping | molding die becomes easy. Also, the correction work when the position is shifted is facilitated.

  Moreover, it is preferable that the said inner surface is connected in the height direction. According to such a configuration, the strength of the semi-solid metal slurry can be further increased.

  According to the method for producing a semi-solid metal slurry and the molten metal holding container of the present invention, the structure and temperature of the semi-solid metal slurry can be made uniform. In addition, according to the semi-solid metal slurry of the present invention, positioning with respect to the mold becomes easy.

It is a figure which shows the molten metal holding | maintenance container which concerns on this embodiment, Comprising: (a) is a perspective view, (b) is sectional drawing. It is a figure which shows the semi-solidified metal slurry which concerns on this embodiment, Comprising: (a) is a perspective view, (b) is sectional drawing. It is sectional drawing which shows the stirring process which concerns on this embodiment. It is a side view which shows the injection | throwing-in process which concerns on this embodiment. It is sectional drawing which shows the temperature distribution of the molten metal which concerns on an Example. (A) is a graph which shows the temperature of the molten metal which concerns on a comparative example, (b) is a graph which shows the temperature of the molten metal which concerns on an Example. (A) is the structure enlarged view of each part which concerns on a comparative example, (b) is the structure enlarged view of each part which concerns on an Example. (A) is sectional drawing which shows the conventional molten metal holding | maintenance container, (b) is the figure which showed the temperature distribution of the molten metal after the conventional stationary process, (c) is the conventional semi-solid metal slurry. It is a figure at the time of throwing into a shaping | molding die.

  Hereinafter, embodiments of a molten metal holding container, a semi-solid metal slurry, and a method for producing a semi-solid metal slurry according to the present invention will be described in detail with reference to the drawings. First, the molten metal holding container will be described.

<Molded metal holding container 10>
As shown in FIG. 1, a molten metal holding container 10 according to the present embodiment is a container that holds molten metal that becomes a forging material. The kind of metal to hold | maintain is not restrict | limited in particular.

  The molten metal holding container 10 has a bottomed cylindrical shape and is open at the top. The molten metal holding container 10 includes a bottom part 11, an outer wall part 12, and an inner wall part 13. In the present embodiment, the molten metal holding container 10 is made of stainless steel (SUS304). As shown in FIG. 1B, the bottom 11 has a ring shape in plan view, and an opening 11a is formed at the center.

  The outer wall portion 12 stands on the outer edge of the bottom portion 11 and has a cylindrical shape. The outer wall portion 12 is formed so that its inner diameter increases toward the tip. A flange 12 a is formed at the tip of the outer wall portion 12.

  The inner wall portion 13 stands on the inner edge of the bottom portion 11 and has a columnar shape. More specifically, the inner wall portion 13 includes a hollow portion 13a inside, and is formed so that its inner diameter and outer diameter become smaller toward the tip. The hollow portion 13a communicates with the vertical direction. In the present embodiment, the inner wall 13 has a height substantially equal to that of the outer wall 12.

  In addition, although the molten metal holding | maintenance container 10 was formed as mentioned above in this embodiment, it is not limited to this. For example, the inner wall portion 13 includes the hollow portion 13a in the present embodiment, but may be solid. Further, the height dimension of the inner wall portion 13 may be larger or smaller than the height dimension of the outer wall portion 12. The inner wall 13 may have another shape as long as it stands on the bottom 11 and has a columnar shape. In the present embodiment, the horizontal cross-sectional shape of the outer wall portion 12 and the inner wall portion 13 is circular, but it may be any shape.

<Semi-solidified metal slurry 20>
Next, as shown in FIG. 2, the semi-solid metal slurry 20 will be described. The semi-solid metal slurry 20 is a metal material formed by the molten metal holding container 10 and in which a solid phase and a liquid phase coexist. The metal type of the semi-solid metal slurry is not particularly limited, but in this embodiment, an aluminum alloy is exemplified. The aluminum alloy according to this embodiment includes at least aluminum, magnesium, and silicon.

  The semi-solid metal slurry 20 has a columnar shape, and includes a bottom surface 21, an outer surface 22, a top surface 23, and an inner surface 24. The bottom surface 21 has a ring shape, and an opening 21a is formed at the center.

  The outer side surface 22 stands on the outer edge of the bottom surface 21 and has a cylindrical shape. The outer side surface 22 is formed such that its diameter decreases toward the tip.

  The top surface 23 is disposed to face the bottom surface 21 and is continuous with the outer surface 22 and the inner surface 24. The top surface 23 has a ring shape and an opening 23a is formed at the center. The opening 23a communicates with the opening 21a.

  The inner side surface 24 stands on the inner edge of the bottom surface 21 and has a columnar shape. More specifically, the inner side surface 24 is provided with a hollow portion 24a inside, and is formed so that its inner diameter increases toward the tip (the top surface 23 side).

  The bottom surface 21, the outer surface 22, the top surface 23, and the inner surface 24 of the semi-solid metal slurry 20 are formed harder than the molten metal existing inside. That is, the surface of the semi-solid metal slurry 20 (the surface in contact with the atmosphere) is solidified and is harder than the molten metal.

  In the present embodiment, the semi-solid metal slurry 20 is configured as described above, but is not limited thereto. For example, the inner side surface 24 of the semi-solid metal slurry 20 is configured to communicate in the vertical direction in the present embodiment, but may be configured not to communicate. Moreover, although the outer side surface 22 is cylindrical, other shapes may be sufficient as long as it is cylindrical.

<Semi-solid forging (Method for producing semi-solid metal slurry)>
Next, semi-solid forging according to this embodiment will be described. In the semi-solid forging according to the present embodiment, a pouring process, a stirring process, a stationary process, a charging process, and a forming process are performed. In this embodiment, the case where the wheel made from an aluminum alloy used for a motor vehicle is manufactured is illustrated, for example.

  In the pouring process, the molten metal Y melted in a holding furnace (not shown) is poured with a ladle or the like and poured into the molten metal holding container 10 (see FIG. 1). The temperature of the molten metal Y is set to about 680 ° C to 720 ° C.

  In the stirring step, as shown in FIG. 3, the molten metal holding container 10 is installed in the electromagnetic stirring device 30. The electromagnetic stirring device 30 includes a magnetic field generator 31 disposed around the outer wall portion 12. In the stirring step, the magnetic field generator 31 generates a magnetic field on the molten metal Y and stirs the molten metal Y in a non-contact manner. Thereby, as shown by the arrow in FIG. 3, the molten metal Y circulates in the order of the outer wall portion 12 → the bottom portion 11 → the inner wall portion 13 → the outer wall portion 12.

  In the standing step, the molten metal Y is left for a predetermined time without stirring. In the stationary step, for example, the temperature of the molten metal is set to 570 to 640 ° C. Moreover, you may perform a cooling process in parallel with a stationary process. In the cooling step, the inner wall portion 13 is cooled by circulating the air cooled by the cooling means through the hollow portion 13a of the inner wall portion 13. In addition, what is necessary is just to perform a cooling process as needed. The semi-solid metal slurry 20 is formed through a stationary process and a cooling process.

  In the charging step, as shown in FIG. 4, the semi-solid metal slurry 20 is charged into the mold 41. Specifically, the molten metal holding container 10 is moved above the mold 41, and the molten metal holding container 10 is tilted to drop the semi-solid metal slurry 20 by its own weight. When the center of the semi-solid metal slurry 20 is not located at the center C of the mold 41, the position is corrected so that the center C and the center of the semi-solid metal slurry 20 overlap.

  In the molding process, the molding dies 41 and 42 are clamped and molded. In the present embodiment, molding is performed with a pressing force of about 12,740 KN. An automobile wheel is formed by the above process. Note that the process from the pouring step to the standing step corresponds to the “method for producing a semi-solid metal slurry”. The semi-solid forging (method for producing a semi-solid metal slurry) of the present embodiment is configured as described above, but is not limited thereto. For example, the stirring step may be performed by other non-contact type stirring devices such as a vibration type and an ultrasonic type. When other non-contact type stirring devices such as a vibration type and an ultrasonic type are used, the molten metal holding container may be formed of a magnetic material. Moreover, you may abbreviate | omit a stirring process as needed.

  As described above, according to the method for producing a semi-solid metal according to the present embodiment, since the columnar inner wall portion 13 is formed in the molten metal holding container 10 as shown in FIG. 3, the primary crystal is formed by the outer wall portion 12 and the inner wall portion 13. α-Al is formed. That is, since the contact area between the molten metal holding container 10 and the molten metal Y is larger than that of the conventional container, a large amount of primary crystal α-Al can be generated. Further, by circulating the convection, the circulating primary crystal α-Al passes not only the outer wall portion 12 but also the vicinity of the inner wall portion 13, thereby preventing re-melting of the primary crystal α-Al. Thereby, the structure and temperature of the semi-solid metal slurry 20 to be manufactured can be made uniform.

  Further, by making the structure and temperature of the semi-solid metal slurry 20 uniform, the strength and toughness of the molded product can be improved. Moreover, the molten metal Y can be stirred in a non-contact manner by performing electromagnetic stirring in the stirring step.

  In addition, according to the method for producing a semi-solid metal, the molten metal Y is cooled by the inner wall portion 13, so that the central portion 100c is heated to a high temperature as in the conventional molten metal holding container 100 shown in FIG. Can be avoided. Thereby, the temperature of the produced semi-solid metal slurry 20 can be made uniform. Further, since the liquid phase is not formed at the central portion of the semi-solid metal slurry 20 as in the prior art, it is possible to prevent the liquid phase portion from seeping out and sticking to the mold 41 in the charging step. Thereby, it can prevent that Si uneven lamination is formed in a molding.

  In the present embodiment, by performing the cooling step, the inner wall 13 can be easily cooled and the cooling temperature can be adjusted.

  Further, according to the molten metal holding container 10 according to the present embodiment, since the molten metal Y is cooled by the inner wall portion 13, it is possible to avoid the central portion of the molten metal holding container from becoming high temperature as in the past. Thereby, the temperature of the produced semi-solid metal slurry 20 can be made uniform. In addition, a cylindrical inner side surface 24 is formed inside the manufactured semi-solid metal slurry 20 by the inner wall portion 13. Thereby, the intensity | strength of the manufactured semi-solidified metal slurry 20 can be raised.

  Further, since the molten metal holding container 10 according to the present embodiment is formed in a hollow cylindrical shape in which the inner wall portion 13 is opened at the bottom portion 11, for example, the molten metal Y is efficiently flowed by flowing a fluid through the inner wall portion 13. Can cool well.

  Further, the inner wall portion 13 of the molten metal holding container 10 tapers toward the tip, and the outer wall portion 12 becomes larger in diameter toward the tip. Thereby, the semi-solid metal slurry 20 can be easily detached from the molten metal holding container 10 during the charging step.

  Moreover, according to the semi-solid metal slurry 20, the cylindrical inner side surface 24 is formed inside. Since the inner side surface 24 is a part which contacts the inner wall part 13 at the time of a stationary process, solidification has advanced. Therefore, the strength of the semi-solid metal slurry 20 can be increased.

  In addition, a cylindrical inner side surface 24 is formed inside the semi-solid metal slurry 20, and the bottom surface 21, the outer side surface 22, the top surface 23, and the inner side surface 24 are formed harder than the internal molten metal Y. Therefore, the strength of the semi-solid metal slurry 20 can be increased. Thereby, since the shape of the semi-solid metal slurry 20 is not easily collapsed when it is put into the mold 41, positioning with respect to the mold 41 is facilitated. Also, the correction work when the position is shifted is facilitated.

  In addition, since the shape of the semi-solid metal slurry 20 is not easily broken by the collision with the mold during the charging process, the cavity of the mold can be uniformly filled. That is, according to this embodiment, the molding accuracy can be improved. Moreover, since the inner surface 24 communicates in the height direction, the strength of the semi-solid metal slurry 20 can be further increased.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described configuration, and design changes can be made as appropriate without departing from the spirit of the present invention. For example, the fluid circulated through the inner wall portion 13 in the cooling process may be any fluid such as liquid or gas. Further, a cooling device or the like may be disposed inside the inner wall portion 13 to cool the inner wall portion 13.

  Next, examples of the present invention will be described. In the example, the semi-solid metal slurry 110 is manufactured using the conventional molten metal holding container 100 shown in FIG. 8, and the semi-solid metal slurry 20 is manufactured using the molten metal holding container 10 according to the present embodiment. Wheels were formed with the solidified metal slurries 110 and 20, respectively, and their properties were investigated.

<Comparison of temperature distribution in molten metal holding container>
FIG. 8B and FIG. 5 show the thermography of the temperature distribution after 3 minutes and 10 seconds have elapsed in the standing step after pouring and stirring molten metal Y having the same temperature. As shown in FIG. 8B, the central portion 100c of the conventional molten metal holding container 100 is dark (dark red in thermography).

  On the other hand, as shown in FIG. 5, the inner wall 13 is formed at the center of the molten metal holding container 10, so that the inner wall 13 has a light color near the inner wall 13 (light yellow in thermography). . That is, since the central portion of the molten metal holding container 10 is less likely to become a high temperature as compared with the comparative example, the liquid phase can be prevented from remaining in the semi-solid metal slurry 20.

<Comparison of temperature in molten metal holding container>
6A is a graph showing the temperature of the molten metal Y according to the comparative example, and FIG. 6B is a graph showing the temperature of the molten metal Y according to the example. The result M1 is a result of measuring the temperature of the central portion in the height direction of the molten metal Y in a predetermined elapsed time. The result M2 is a result of measuring the temperature of the lower part of the molten metal Y in the height direction during a predetermined elapsed time.

  On the other hand, as shown in FIG. 6B, the result N1 is a result of measuring the temperature of the central portion in the height direction of the molten metal Y in a predetermined elapsed time. The result N2 is a result of measuring the temperature of the lower portion of the molten metal Y in the height direction during a predetermined elapsed time.

  As shown in FIG. 6A, when the temperature of the molten metal Y after 3 minutes and 10 seconds elapses, the result M1 is 614 ° C. (Max temperature), and the result M2 is 582 ° C. (Min temperature). . The temperature difference between the results M1 and M2 is 32 ° C.

  On the other hand, as shown in FIG. 6B, when the temperature of the molten metal Y after 3 minutes and 10 seconds elapses, the result N1 is 601 ° C. (Max temperature), and the result N2 is 584 ° C. (Min temperature). It is. The temperature difference between the results N1 and N2 is 17 ° C. That is, in the comparative example, the temperature difference is 32 ° C., whereas in the example, the temperature difference is 17 ° C. Therefore, in the embodiment, the temperature difference in the molten metal Y held as compared with the comparative example can be eliminated, and the temperature can be made uniform.

<Comparison of wheel structures>
FIG. 7A is an enlarged view of the structure of each part according to the comparative example, and FIG. 7B is an enlarged view of the structure of each part according to the example. In the comparative example, when the wheel W is formed by the semi-solid metal slurry 110 manufactured by the conventional molten metal holding container 100, the outer flange portion J1 in the portion surrounded by L of the wheel W shown in FIG. The structure of the spoke part K1 was observed with an electron microscope.

  On the other hand, in the embodiment, as shown in FIG. 7 (b), when the wheel W is formed with the semi-solid metal slurry 20 manufactured in the molten metal holding container 10, the outer flange portion J2 and the spoke portion K2 The tissue was observed with an electron microscope.

  As shown to (a) of FIG. 7, in outer flange part J1, it turns out that aluminum particle | grains are formed finely and silicon, magnesium, etc. are arrange | positioned with good balance between aluminum particles. However, it can be seen that the spoke portion K1 in FIG. 7A is substantially made of only aluminum and a so-called aluminum-rich layer is formed. When the strength and proof stress of the spoke portion K1 are measured, it is about ½ of the strength and proof strength of the outer flange portion J1. In the conventional wheel, since the balance of strength and proof stress is poor in the spoke portion K1 and the outer flange portion J1, the strength of the wheel W as a whole is reduced.

  On the other hand, as shown in FIG. 7B, neither the aluminum-rich layer is seen in the outer flange portion J2 or the spoke portion K2, the aluminum particles are finely formed, and silicon or silicon is between the aluminum particles. It turns out that magnesium etc. are arranged with good balance. This is considered due to the fact that the temperature and structure of the semi-solid metal slurry 20 are made uniform by the molten metal holding container 10.

DESCRIPTION OF SYMBOLS 10 Molten metal holding container 11 Bottom part 11a Opening 12 Outer wall part 12a Flange 13 Inner wall part 13a Hollow part 20 Semi-solid metal slurry 21 Bottom surface 22 Outer side surface 23 Top surface 24 Inner side surface 24a Hollow part 30 Electromagnetic stirrer 31 Magnetic field generator 41 Mold 42 Mold Y Molten metal

Claims (10)

A method for producing a semi-solid metal slurry in which a solid phase and a liquid phase coexist,
A stirring step of stirring the molten metal in the molten metal holding container in a non-contact manner;
The molten metal holding container has a bottom portion, a cylindrical outer wall portion standing on the bottom portion, and a columnar inner wall portion standing on the inner side of the outer wall portion at the bottom portion,
In the stirring step, a molten metal is convected between the outer wall portion and the inner wall portion. The molten metal holding container is a non-magnetic material,
The method for producing a semi-solid metal slurry according to claim 1, wherein electromagnetic stirring is performed in the stirring step. A method for producing a semi-solid metal slurry in which a solid phase and a liquid phase coexist,
Including a standing step of standing the molten metal in the molten metal holding container,
The molten metal holding container has a bottom portion, a cylindrical outer wall portion standing on the bottom portion, and a columnar inner wall portion standing on the inner side of the outer wall portion at the bottom portion,
In the stationary step, the molten metal is cooled by contacting the molten metal with the inner wall portion, and the method for producing a semi-solid metal slurry, A hollow portion is formed in the inner wall portion,
The method for producing a semi-solid metal slurry according to claim 1 or 3, further comprising a cooling step in which a fluid is allowed to flow through the hollow portion to cool the molten metal. The bottom,
A cylindrical outer wall standing on the bottom,
A columnar inner wall portion standing on the inner side of the outer wall portion at the bottom, and
A molten metal holding container, wherein the molten metal is cooled by contacting the molten metal with the outer wall portion and the inner wall portion while holding the molten metal between the outer wall portion and the inner wall portion. .   The molten metal holding container according to claim 5, wherein the columnar inner wall portion is formed in a hollow cylindrical shape that opens at least at the bottom portion.   The molten metal holding container according to claim 5 or 6, wherein the inner wall portion extends to a height equal to or higher than the height of the outer wall portion.   The molten metal holding container according to any one of claims 5 to 7, wherein the inner wall portion is tapered toward the tip. A semi-solid metal slurry in which a solid phase and a liquid phase coexist,
The bottom,
A cylindrical outer surface standing on the bottom surface;
A top surface that is continuous with the outer surface and faces the bottom surface;
A cylindrical inner surface erected inward from the outer surface at the bottom surface;
A hollow portion formed inside the inner surface,
The bottom surface, the outer side surface, the top surface, and the inner side surface are formed to be harder than the inner molten metal.   The semi-solid metal slurry according to claim 9, wherein the inner surface communicates in a height direction.