Patent Publication Number: US-11040392-B2

Title: Casting device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2019-207070 filed on Nov. 15, 2019, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a casting device. 
     2. Description of Related Art 
     A casting device is a device that manufactures a cast product by injecting a molten metal into a cavity of a mold. The technical paper JD18-25 presented at the 2018 Japan Die Casting Congress titled “Photography of atomization phenomena in HPDC and development of simulation system for atomized flow by LES-VOF method” discloses that effects such as reduction of an amount of defects in a cast product and improvement of elongation property of the product can be achieved by adopting an atomized flow for the molten metal to be injected into a cavity of the mold. The technical paper JD18-25 presented at the 2018 Japan Die Casting Congress titled “Photography of atomization phenomena in HPDC and development of simulation system for atomized flow by LES-VOF method” discloses a technology that the molten metal can be atomized by increasing a speed at which the molten metal passes through a gate (i.e. gate speed). 
     SUMMARY 
     As described above, by atomizing the molten metal supplied to the cavity of the mold, it is possible to reduce the amount of defects in the cast product. For example, the technical paper JD18-25 presented at the 2018 Japan Die Casting Congress titled “Photography of atomization phenomena in HPDC and development of simulation system for atomized flow by LES-VOF method” discloses a technology that the molten metal can be atomized by increasing a speed at which the molten metal passes through the gate (i.e. gate speed). 
     However, there is an issue that if the gate speed of the molten metal increases, an amount of heat transferred to a flow path of the molten metal and the mold also increases, which causes erosion and seizure. Therefore, there is a need for a technology that enables atomization of the molten metal without increasing the gate speed of the molten metal. 
     The present disclosure provides a casting device that is capable of atomizing the molten metal without increasing the gate speed of the molten metal. 
     A casting device according to an aspect of the present disclosure includes a mold having a cavity, a supply path that is connected to a gate of the cavity and configured to supply a molten metal to the cavity, and a gas flow path that is connected to the supply path and configured to supply a gas to the supply path. In the casting device, the molten metal is atomized by causing the gas supplied from the gas flow path to collide with the molten metal passing through the supply path, and the molten metal that is atomized is supplied to the cavity. 
     In the casting device according to the aspect of the present disclosure, the molten metal is atomized by causing the gas to collide with the molten metal passing through the supply path. Therefore, the molten metal can be atomized without increasing the speed of the molten metal that passes through the gate (i.e. gate speed). 
     According to the aspect above, the casting device may include a molten metal supply portion that connected to the supply path and is configured to supply the molten metal to the supply path. The molten metal supply portion may be configured such that a sectional area of the molten metal supply portion is smaller than a sectional area of the supply path at a portion at which the molten metal supply portion is connected to the supply path. With this configuration, the molten metal can be effectively diffused in the supply path, whereby atomization of the molten metal can be promoted. 
     According to the aspect above, the gas flow path may be disposed such that a direction in which the gas is supplied to the supply path forms an acute angle with respect to a direction in which the molten metal flows through the supply path. With this configuration, supply of the atomized molten metal to the cavity can be promoted while the molten metal in the supply path is atomized. 
     According to the aspect above, a sectional shape of the supply path may be circular, a plurality of the gas flow paths may be connected to a periphery of the supply path, and the gas flow paths may be each disposed such that the direction in which the gas is supplied to the supply path is deviated from a central axis of the supply path when the gas is supplied toward the direction in which the molten metal flows through the supply path. The sectional shape of the supply path is not limited to truly circular. The sectional shape of the supply path may be substantially circular. With this configuration, the flow of the molten metal in the supply path can be rotated. When the flow of the molten metal is rotated as described above, a centrifugal force acts on the molten metal, which promotes disturbance of the flow of the molten metal. Therefore, atomization of the molten metal is promoted. 
     According to the aspect above, a first end of the gas flow path may be connected to the supply path, a second end of the gas flow path may be connected to the cavity, and the gas may supplied from the cavity to the supply path through the gas flow path. With this configuration, the air can be discharged through the gas flow path from the portions of the cavity where the air is likely to accumulate, and thus it is possible to suppress accumulation of the air in the cavity. Accordingly, the quality of the cast product can be improved. 
     According to the aspect above, the gas flow path may include a first gas flow path and a second gas flow path. The first gas flow path may be connected to the supply path and configured to supply a first gas to the supply path. A first end of the second gas flow path may be connected to the supply path and a second end of the second gas flow path may be connected to the cavity, and the gas may be supplied from the cavity to the supply path through the second gas flow path. With this configuration, the gas for atomizing the molten metal can be sufficiently supplied to the supply path. Therefore, atomization of the molten metal flowing through the supply path can be promoted. 
     According to the aspect above, the present disclosure can provide a casting device that is capable of atomizing the molten metal without increasing the gate speed of the molten metal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is sectional view for explaining a casting device according to a first embodiment; 
         FIG. 2  is a sectional view for explaining another configuration example of the casting device according to the first embodiment; 
         FIG. 3  is a sectional view for explaining still another configuration example of the casting device according to the first embodiment; 
         FIG. 4  is a sectional view for explaining a casting device according to a second embodiment; 
         FIG. 5  is a sectional view for explaining the casting device according to the second embodiment; and 
         FIG. 6  is a sectional view for explaining another configuration example of the casting device according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.  FIG. 1  is sectional view for explaining a casting device according to a first embodiment. As shown in  FIG. 1 , a casting device  1  according to the first embodiment includes a mold  10 , a supply path  13 , a molten metal supply portion  14 , and a gas flow path  16 . 
     The mold  10  includes a cavity  11  corresponding to a shape of a cast product to be manufactured. For example, the mold  10  includes a fixed mold and a movable mold. The cavity  11  corresponding to the shape of the product is formed inside the mold  10  by coupling the movable mold to the fixed mold and fastening the molds together. A molten metal  25  is then supplied (injected) to the cavity  11  to cast the cast product and the movable mold is separated from the fixed mold to open the mold  10 , whereby the cast product is taken out from the mold  10 . Subsequently, the cast products can be continuously manufactured by repeating the process similar to the above. In this specification, the fixed mold and the movable mold are not illustrated in the drawings in order to simplify the drawings. 
     The supply path  13  is a flow path for supplying the molten metal  25  to the cavity  11 . The supply path  13  is connected to a gate  12  of the mold  10  (the cavity  11 ), and supplies a molten metal  21  supplied from the molten metal supply portion  14  to the cavity  11  through the gate  12 . The molten metal  21  moves through the supply path  13  in an x-axis direction. At this time, the molten metal  21  supplied from the molten metal supply portion  14  is atomized in the supply path  13 , and the atomized molten metal  25  is supplied to the cavity  11 . Note that, in this specification, a molten metal before atomization is referred to as the “molten metal  21 ”, and an atomized molten metal is referred to as the “molten metal  25 ”. 
     The molten metal supply portion  14  is connected to the supply path  13  to supply the molten metal  21  to the supply path  13 . For example, the molten metal supply portion  14  may be configured using a plunger. Specifically, the plunger (not illustrated) includes a plunger sleeve and a plunger tip. The molten metal  21  is supplied to the supply path  13  by the plunger tip sliding in the plunger sleeve filled with the molten metal  21 . The molten metal  21  is a liquid material obtained by melting a metal that is a material of a cast product, and for example, a molten metal obtained by melting an aluminum alloy. 
     The molten metal supply portion  14  is configured such that a sectional area of the molten metal supply portion  14  is smaller than a sectional area of the supply path  13  (a section perpendicular to the x-axis) at a portion  14   a  at which the molten metal supply portion  14  is connected to the supply path  13 . 
     The gas flow path  16  is connected to the supply path  13  and supplies a gas  22  to the supply path  13 . In the casting device  1  according to the first embodiment, the molten metal  21  is atomized by causing the gas  22  supplied from the gas flow path  16  to collide with the molten metal  21  passing through the supply path  13 , and then the atomized molten metal  25  is supplied to the cavity  11 . 
     In the example shown in  FIG. 1 , the gas  22  supplied to the supply path  13  is supplied (injected) from the gas flow path  16  in a y-axis direction. That is, the gas  22  is supplied from the gas flow path  16  in the y-axis direction toward the molten metal  21  that is flowing in the x-axis direction and the gas  22  collides with the molten metal  21  so as to atomize the molten metal  21 . With this configuration, a shearing force of the gas  22  acts on the molten metal  21  as the gas  22  collides with the molten metal  21 , which atomizes the molten metal  21 . 
     Specifically, in the first embodiment, when the molten metal  25  is supplied from the supply path  13  to the cavity  11 , the air in the supply path  13  is pushed out from the supply path  13  due to an inertia force of the molten metal  25  and a viscous force of the air. Consequently, the pressure in the supply path  13  becomes negative. This supplies the gas  22  from the gas flow path  16  to the supply path  13 . Further, the molten metal supply portion  14  is configured such that the sectional area of the molten metal supply portion  14  is smaller than the sectional area of the supply path  13  (the section perpendicular to the x-axis) at the portion  14   a  at which the molten metal supply portion  14  is connected to the supply path  13 . With this configuration, the molten metal  21  can be effectively diffused in the supply path  13 , whereby atomization of the molten metal  21  can be promoted. That is, in the casting device  1  according to the first embodiment, the molten metal  21  can be atomized using the principle of air-assist atomizer. 
     The gas  22  supplied from the gas flow path  16  to the supply path  13  may be an air or an inert gas. As the inert gas, nitrogen gas and argon gas, for example, may be used. 
     Further, in the first embodiment, a flow rate (flow velocity) of the gas  22  supplied from the gas flow path  16  to the supply path  13  may be adjusted in accordance with a flow rate (speed) of the molten metal  21  passing through the supply path  13 . For example, as the flow rate of the molten metal  21  passing through the supply path  13  increases, the flow rate of the gas  22  supplied from the gas flow path  16  to the supply path  13  may be increased. For example, the flow rate of the gas  22  supplied from the gas flow path  16  to the supply path  13  can be adjusted by providing a valve for adjusting the flow rate in the gas flow path  16 . 
     As described above, in the first embodiment, when the molten metal  21  is flowing through the supply path  13 , the gas  22  is supplied from the gas flow path  16  to the supply path  13  as the pressure in the supply path  13  becomes negative. However, in the first embodiment, the gas  22  may be supplied from the gas flow path  16  to the supply path  13  by supplying a pressurized gas to the gas flow path  16 . For example, a compressed air that is pressurized at a predetermined pressure may be supplied from the gas flow path  16  to the supply path  13 . With this configuration, the speed of the gas  22  that collides with the molten metal  21  passing through the supply path  13  increases and thus a collision energy increases. Therefore, atomization of the molten metal  21  can be promoted. 
     As described above, in the casting device  1  according to the first embodiment, the molten metal  21  is atomized by causing the gas  22  to collide with the molten metal  21  passing through the supply path  13 . Therefore, the molten metal can be atomized without increasing the speed of the molten metal passing through the gate  12  (i.e. gate speed). Further, in the casting device  1  according to the first embodiment, there is no need to increase the gate speed. Therefore, an increase in the amount of heat transferred to the flow path of the molten metal and the mold can be suppressed, which can suppress occurrence of erosion and seizure. 
     In the first embodiment, the gas  22  supplied to the supply path  13  may be heated in advance. Heating of the gas  22  in advance can suppress the molten metal  21  from cooling by the gas  22  when the gas  22  collides with the molten metal  21  passing through the supply path  13 . Therefore, it is possible to suppress the molten metal  21  from turning into metal particles due to the lowered temperature of the molten metal  21 . 
       FIG. 2  is a sectional view for explaining another configuration example of the casting device according to the first embodiment. A casting device  1   a  shown in  FIG. 2  has a different arrangement of a gas flow path  17  compared to the casting device  1  shown in  FIG. 1 . The configurations of other components of the casting device  1   a  are the same as the configurations of the casting device  1  shown in  FIG. 1 . 
     As shown in  FIG. 2 , the gas flow path  17  of the casting device  1   a  is disposed such that a direction in which a gas  23  is supplied to the supply path  13  forms an acute angle with respect to a direction in which the molten metal  21  flows through the supply path  13  (in the x-axis direction). In this case as well, a shearing force of the gas  23  acts on the molten metal  21  as the gas  23  collides with the molten metal  21  flowing in the x-axis direction, which atomizes the molten metal  21 . Further, supply of the atomized molten metal  25  to the cavity  11  can be promoted while the molten metal  21  is atomized by forming an acute angle by the direction in which the gas  23  is supplied to the supply path  13  with respect to the direction in which the molten metal  21  flows (the x-axis direction). 
     At this time, in the first embodiment, the direction in which the gas  23  is supplied to the supply path  13  may be configured to be adjustable. For example, as the angle formed by the direction in which the gas  23  is supplied to the supply path  13  with respect to the direction in which the molten metal  21  flows through the supply path  13  (the x-axis direction) becomes larger (becomes closer to the right angle), a colliding force of the gas  23  applied to the molten metal  21  increases, which promotes atomization of the molten metal  21 . On the other hand, as the angle formed by the direction in which the gas  23  is supplied to the supply path  13  with respect to the direction in which the molten metal  21  flows through the supply path  13  (the x-axis direction) becomes smaller (as the direction in which the gas  23  is supplied to the supply path  13  becomes closer to the x-axis), a momentum of the atomized molten metal  25  flowing along the x-axis direction can be strengthened. Therefore, it is possible to promote supply of the atomized molten metal  25  to the cavity  11 . In the first embodiment, the direction in which the gas  23  is supplied to the supply path  13 , that is, the angle at which the gas  23  collides with the molten metal  21  flowing through the supply path  13 , may be adjusted taken into account the above. 
     Note that, in  FIG. 1 , as examples, the number of the gas flow path  16  that is connected to the supply path  13  is one. However, according to the first embodiment, the number of the gas flow paths  16  that are connected to the supply path  13  may be two or more. In  FIG. 2 , as examples, the number of the gas flow path  17  that is connected to the supply path  13  is one. However, according to the first embodiment, the number of the gas flow paths  17  that are connected to the supply path  13  may be two or more. 
       FIG. 3  is a sectional view for explaining another configuration example of the casting device according to the first embodiment, and shows an example in which a plurality of gas flow paths  17   a  to  17   h  is provided for the supply path  13 .  FIG. 3  shows an example in which a plurality of the gas flow paths  17 , each of which corresponds to the one that is shown in  FIG. 2 , is disposed on a periphery of the supply path  13 . That is, the gas flow paths  17   a  to  17   h  are each disposed such that, similar to the gas flow path  17  shown in  FIG. 2 , the direction in which the gas  23  is supplied to the supply path  13  forms an acute angle with respect to the direction in which the molten metal  21  flows through the supply path  13  (i.e. the x-axis direction). 
     The sectional shape of the supply path  13  shown in  FIG. 3  is substantially circular, and the gas flow paths  17   a  to  17   h  are connected to the periphery of the supply path  13 . At this time, the gas flow paths  17   a  to  17   h  are each disposed such that the direction in which the gas  23  is supplied to the supply path  13  is deviated from a central axis  29  of the supply path  13  when viewed in the direction in which the molten metal  21  flows through the supply path  13  (i.e. the x-axis direction). 
     The flow of the molten metal  21  in the supply path  13  can be rotated by disposing the gas flow paths  17   a  to  17   h  as described above. In the example shown in  FIG. 3 , the flow of the molten metal  21  in the supply path  13  along the x-axis direction can be rotated clockwise. When the flow of the molten metal  21  is rotated as described above, a centrifugal force acts on the molten metal  21 , which promotes disturbance of the flow of the molten metal  21 . Therefore, atomization of the molten metal  21  is promoted. 
     Also, in the configuration shown in  FIG. 3 , the direction in which the molten metal  25  is supplied from the supply path  13  to the cavity  11  may be controlled by adjusting the flow rates of the gas flowing through the respective gas flow paths  17   a  to  17   h . For example, when it is desired to supply a larger amount of the molten metal  25  to the positive side of the cavity  11  in the y-axis direction, the supply amount of the gas  23  from the gas flow path on the negative side in the y-axis direction among the gas flow paths  17   a  to  17   h  is increased. On the contrary, when it is desired to supply a larger amount of the molten metal  25  to the negative side of the cavity  11  in the y-axis direction, the supply amount of the gas  23  from the gas flow path on the positive side in the y-axis direction among the gas flow paths  17   a  to  17   h  is increased. By using the method above, it is possible to supply the molten metal  25  mainly to the portion of the cavity  11  where supply of a larger amount of the molten metal  25  is required. 
     According to the first embodiment, the present disclosure can provide a casting device that enables atomization of the molten metal without increasing the gate speed of the molten metal. 
     Second Embodiment 
     Next, a second embodiment of the present disclosure will be described.  FIG. 4  is a sectional view for explaining a casting device according to the second embodiment. As shown in  FIG. 4 , a casting device  2  according to the second embodiment includes the mold  10 , the supply path  13 , the molten metal supply portion  14 , and gas flow paths  18   a ,  18   b . Note that, the casting device  2  according to the second embodiment has different configurations of the gas flow paths  18   a ,  18   b , compared to the casting device  1  described in the first embodiment (refer to  FIG. 1 ). The configurations of the casting device  2  other than the gas flow paths are the same as those of the casting device  1  described in the first embodiment. Therefore, the same constituent elements are denoted by the same reference numerals, and redundant description thereof will be omitted. 
     As shown in  FIG. 4 , in the casting device  2  according to the second embodiment, the gas flow paths  18   a ,  18   b  are provided so as to connect spaces in the cavity  11  and the supply path  13 . Specifically, one ends of the gas flow paths  18   a ,  18   b  are connected to the supply path  13 , and the other ends of the gas flow paths  18   a ,  18   b  are connected to the cavity  11 . 
     In the casting device  2  according to the second embodiment, the gas flow paths  18   a ,  18   b  are configured as described above. Therefore, the gas is supplied from the cavity  11  to the supply path  13  through the gas flow paths  18   a ,  18   b . That is, when the molten metal  25  is supplied from the supply path  13  to the cavity  11 , the air in the supply path  13  is pushed out from the supply path  13  due to the inertia force of the molten metal  25  and the viscous force of the air, which makes the pressure in the supply path  13  negative. With this configuration, the gas in the cavity  11  is sucked into the gas flow paths  18   a ,  18   b , and sucked gases  24   a ,  24   b  are supplied to the supply path  13 . 
     Further, in the second embodiment, as shown in  FIG. 5 , the pressure in the cavity  11  increases as the molten metal  25  is supplied to the cavity  11  and thus a molten metal  26  is filled in the cavity  11 . With this configuration, the gas in the cavity  11  is pushed out from the cavity  11  to the gas flow paths  18   a ,  18   b , and the gases  24   a ,  24   b  that are pushed out from the cavity  11  is supplied to the supply path  13 . 
     In the second embodiment, the gases  24   a ,  24   b  are supplied from the cavity  11  to the supply path  13  through the gas flow paths  18   a ,  18   b  by two actions as described above. 
     Further, in the second embodiment, with the configuration above, the air in the cavity  11  can be discharged from portions  31   a ,  31   b  in the cavity  11  where the air is likely to accumulate (refer to  FIG. 5 ). That is, the cavity  11  includes the portions  31   a ,  31   b  where the molten metal does not flow as desired, and the air tends to accumulate in the portions  31   a ,  31   b . In the second embodiment, the air can be discharged from the portions  31   a ,  31   b  of the cavity  11  where the air is likely to accumulate by connecting the gas flow paths  18   a ,  18   b  in the proximity to the portions  31   a ,  31   b , respectively. With this configuration, accumulation of the air in the cavity  11  can be suppressed when the molten metal  26  is filled in the cavity  11 , whereby the quality of the cast product can be improved. 
     For example, in the cavity  11 , the molten metal tends to fail to flow as desired on the side closer to the gate  12 . Therefore, for example, the gas flow paths  18   a ,  18   b  may be connected to respective positions that are closer to the gate  12  than the center of gravity of the cavity  11 . 
     Further,  FIG. 4  shows an example in which the casting device  2  is provided with two gas flow paths  18   a ,  18   b . However, in the second embodiment, the number of the gas flow paths provided in the casting device  2  may be one, or three or more. 
     As described above, in the casting device  2  according to the second embodiment, the molten metal  21  is atomized by causing the gas  22  to collide with the molten metal  21  passing through the supply path  13 . Therefore, the molten metal can be atomized without increasing the speed of the molten metal passing through the gate  12  (i.e. gate speed). Further, in the casting device  2  according to the second embodiment, there is no need to increase the gate speed. Therefore, an increase in the amount of heat transferred to the flow path of the molten metal and the mold can be suppressed, which can suppress occurrence of erosion and seizure. 
     Further, in the casting device  2  according to the second embodiment, one ends of the gas flow paths  18   a ,  18   b  are connected to the supply path  13 , and the other ends of the gas flow paths  18   a ,  18   b  are connected to the cavity  11 . Therefore, the air can be discharged from the portions  31   a ,  31   b  of the cavity  11  where the air is likely to accumulate, and thus it is possible to suppress accumulation of the air in the cavity  11 . Accordingly, the quality of the cast product can be improved. 
     Next, another configuration example of the casting device according to the second embodiment will be described.  FIG. 6  is a sectional view for explaining another configuration example of the casting device according to the second embodiment. A casting device  2   a  shown in  FIG. 6  is a configuration example in which the casting device  2  of the second embodiment that is shown in  FIG. 4  and the casting device  1  of the first embodiment that is shown in  FIG. 1  are combined. Among the configurations of the casting device  2   a  shown in  FIG. 6 , the configurations that are common to the configurations of the casting device  2  shown in  FIG. 4  and the casting device  1  shown in  FIG. 1  are denoted by the same reference numerals. 
     The casting device  2   a  shown in  FIG. 6  includes the gas flow path (first gas flow path)  16  and the gas flow paths (second gas flow paths)  18   a ,  18   b . The gas flow path  16  is connected to the supply path  13  and is configured to be capable of supplying the gas  22  to the supply path  13 . One ends of the gas flow paths  18   a ,  18   b  are connected to the supply path  13  and the other ends of the gas flow paths  18   a ,  18   b  are connected to the cavity  11 . The gases  24   a ,  24   b  is supplied from the cavity  11  to the supply path  13  through the gas flow paths  18   a ,  18   b.    
     For example, in the casting device  2  shown in  FIG. 4 , the gases  24   a ,  24   b  are supplied from the cavity  11  to the supply path  13  through the gas flow paths  18   a ,  18   b . However, depending on the amount of the molten metal  21  flowing through the supply path  13 , there may be a case where the amounts of the gases  24   a ,  24   b  supplied to the supply path  13  are not enough, and thus the molten metal  21  flowing through the supply path  13  cannot be sufficiently atomized. In such a case, as in the casting device  2   a  shown in  FIG. 6 , the molten metal  21  flowing through the supply path  13  can be sufficiently atomized by further providing the gas flow path  16  and supplying the gas  22  to the supply path  13 . That is, the gas required for atomizing the molten metal  21  can be supplemented by additionally providing the gas flow path  16 . Therefore, atomization of the molten metal  21  flowing through the supply path  13  can be promoted. 
     As described above, the gas  22  supplied from the gas flow path  16  to the supply path  13  may be the air or an inert gas. As the inert gas, nitrogen gas and argon gas, for example, may be used. 
     Further, the flow rate (flow velocity) of the gas  22  supplied from the gas flow path  16  to the supply path  13  may be adjusted in accordance with the flow rate (speed) of the molten metal  21  passing through the supply path  13 . For example, as the flow rate of the molten metal  21  passing through the supply path  13  increases, the flow rate of the gas  22  supplied from the gas flow path  16  to the supply path  13  may be increased. For example, the flow rate of the gas  22  supplied from the gas flow path  16  to the supply path  13  can be adjusted by providing a flow rate adjusting valve in the gas flow path  16 . 
     As described above, the gas  22  supplied from the gas flow path  16  to the supply path  13  may be supplied to the supply path  13  when the pressure in the supply path  13  becomes negative. Further, the gas  22  may be supplied from the gas flow path  16  to the supply path  13  by supplying the pressurized gas to the gas flow path  16 . For example, the compressed air that is pressurized at a predetermined pressure may be supplied from the gas flow path  16  to the supply path  13 . 
     Further, similar to the gas flow path  17  shown in  FIG. 2 , the gas flow path  16  may be disposed such that the direction in which the gas is supplied to the supply path  13  forms an acute angle with respect to the direction in which the molten metal  21  flows through the supply path  13  (i.e. the x-axis direction). 
     The embodiments for carrying out the present disclosure have been described above, but the present disclosure is not limited to the specific embodiments as described above. The present disclosure includes various modifications, corrections, and combinations that can be made by those who are skilled in the art without departing from the scope of the present disclosure described in the claims.