Abstract:
An up-thawing continuous casting apparatus includes a holding furnace that holds molten metal; a shape determining member that is arranged near a molten metal surface of a casting held in the holding furnace, and that determines a sectional shape of the molten metal by the molten metal passing through the shape determining member; a cooling portion that cools and solidifies the molten metal that has passed through the shape determining member; and a molten metal cooling portion that lowers a temperature of the molten metal held in the holding furnace.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to an up-drawing continuous casting apparatus and an up-drawing continuous casting method. 
         [0003]    2. Description of Related Art 
         [0004]    In Japanese Patent Application Publication No. 2012-61518 (JP 2012-61518 A), the inventors propose a free casting method as a groundbreaking continuous casting method that does not require a mold. As described in JP 2012-61518 A, a starter is first immersed into the surface of molten metal (a molten metal surface), and then when the starter is drawn up, molten metal is also drawn out following the starter by surface tension and the surface film of the molten metal. Here, a casting that, has a desired sectional shape is able to be continuously cast by drawing out the molten metal via a shape determining member arranged near the molten metal surface, and cooling it (i.e., the drawn out molten metal). 
         [0005]    With a normal continuous casting method, the sectional shape and the shape in the longitudinal direction are both determined by a mold. In particular, the solidified metal (i.e., the casting) must pass through the mold, so the cast casting takes on a shape that extends linearly in the longitudinal direction. In contrast, the shape determining member in the free casting method determines only the sectional shape of the casting, the shape in the longitudinal direction is not determined. Also, the shape determining member is able to move in a direction parallel to the molten metal surface (i.e., horizontally), so castings of various shapes in the longitudinal direction are able to be obtained. For example, JP 2012-61518 A describes a hollow casting (i.e., a pipe) formed in a zigzag shape or a helical shape, not a linear shape in the longitudinal direction. 
         [0006]    The inventors discovered that with the free casting method described in JP 2012-61518 A, the molten metal drawn out via the shape determining member is cooled by only cooling gas, so the casting speed is slow, which is problematic in terms of productivity. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention thus provides an up-drawing continuous casting apparatus and an up-drawing continuous casting method that increases casting speed, and thus offers excellent productivity. 
         [0008]    A first aspect of the invention relates to an up-drawing continuous casting apparatus. This up-drawing continuous casting apparatus includes a holding furnace that holds molten metal; a shape determining member that is arranged near a molten metal surface of the molten metal held in the holding furnace, and that determines a sectional shape of a casting by the molten metal passing through the shape determining member; a cooling portion that cools and solidifies the molten metal that has passed through the shape determining member; and a molten metal cooling portion that lowers a temperature of the molten metal held in the holding furnace. 
         [0009]    According to this first aspect, casting speed is able to be increased, so productivity is able to be improved. 
         [0010]    In the first aspect described above, the molten metal cooling portion may be provided directly below the shape determining member. 
         [0011]    With this structure, the temperature of the molten metal positioned directly below the shape determining member is able to be lowered in a short period of time, so the casting speed is able to be increased. 
         [0012]    The up-drawing continuous casting apparatus of the first aspect described above may also include an actuator that moves the molten metal cooling portion in a top-bottom direction inside the holding furnace. 
         [0013]    In the first aspect described above, cooling gas may pass through an inside of the molten metal cooling portion. 
         [0014]    In the first aspect described above, the molten metal cooling portion may be made of ceramic. 
         [0015]    The up-drawing continuous casting apparatus of the first aspect described above may also include a partition wall that surrounds the molten metal, and an ambient temperature regulating portion that regulates a temperature of an atmosphere surrounded by the partition wall. 
         [0016]    According to the first aspect described above, the quality of a casting is able to be made stable. 
         [0017]    A second aspect of the invention relates to an up-drawing continuous casting method that uses a casting apparatus having a shape determining member that determines a sectional shape of a casting, a holding furnace that holds a molten metal, and a molten metal cooling portion provided in the holding furnace. The up-drawing continuous casting method includes arranging the shape determining member near a molten metal surface of the molten metal held in the holding furnace; lowering a temperature of the molten metal held in the holding furnace, with the molten metal cooling portion; passing the molten metal that has been lowered in temperature through the shape determining member and drawing up the molten metal; and cooling the molten metal that has passed through the shape determining member and been drawn up. 
         [0018]    According to this second aspect, casting speed is able to be increased, so productivity is able to be improved. 
         [0019]    In the second aspect described above, the molten metal cooling portion may be provided directly below the shape determining member. 
         [0020]    With this structure, the temperature of the molten metal positioned directly below the shape determining member is able to be lowered in a short period of time, so the casting speed is able to be increased. 
         [0021]    The up-drawing continuous casting method of the second aspect described above may also include moving the molten metal cooling portion in a top-bottom direction inside the holding furnace. 
         [0022]    In the second aspect described above, lowering the temperature of the molten metal may be done by leading cooling gas into the molten metal cooling portion. 
         [0023]    In the second aspect described above, the molten metal cooling portion may be made of ceramic. 
         [0024]    The up-drawing continuous casting method of the second aspect described above may also include surrounding the molten metal with a partition wall, and regulating a temperature of an atmosphere surrounded by the partition wall. 
         [0025]    According to the second aspect described above, the quality of a casting is able to be made stable. 
         [0026]    A third aspect of the invention relates to an up-drawing continuous casting apparatus. This up-drawing continuous casting apparatus includes a holding furnace that holds molten metal; a shape determining member that is arranged near a molten metal surface of the molten metal held in the holding furnace, and that determines a sectional shape of a casting by the molten metal passing through the shape determining member; and a cooling portion that cools and solidifies the molten metal that has passed through the shape determining member with a starter. The starter has a cooling mechanism that is integrated with the starter. 
         [0027]    According to this third aspect, casting speed is able to be increased, so productivity is able to be improved. 
         [0028]    In the third aspect described above, the cooling mechanism may include a pipe that is attached to the starter and into which coolant is introduced. 
         [0029]    In the third aspect described above, the cooling mechanism may be the starter itself that is formed by a pipe into which coolant is introduced. 
         [0030]    A fourth aspect of the invention relates to an up-drawing continuous casting method that uses a casting apparatus having a shape determining member that determines a sectional shape of a casting, a holding furnace that holds a molten metal, a starter, and a cooling mechanism that is integrated with the starter. The up-drawing continuous casting method includes arranging the shape determining member near a molten metal surface of the molten metal held in the holding furnace; passing the molten metal through the shape determining member and drawing up the molten metal with the starter; cooling and solidifying the molten metal that has passed through the shape determining member and been drawn up; and cooling the starter with the cooling mechanism. 
         [0031]    According to this fourth aspect, casting speed is able to be increased, so productivity is able to be improved. 
         [0032]    In the fourth aspect described above, the cooling mechanism may be formed by attaching a pipe to the starter and introducing coolant into the pipe. 
         [0033]    In the fourth aspect described above, the cooling mechanism may be formed by introducing coolant into the starter itself that is formed by a pipe. 
         [0034]    According to the, first to the fourth aspects of the invention, it is possible to provide an up-drawing continuous casting apparatus and an up-drawing continuous casting method that increases casting speed, and thus offers excellent productivity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
           [0036]      FIG. 1  is a sectional view of a free casting apparatus according to a first example embodiment of the invention; 
           [0037]      FIG. 2  is a plan view of an inner shape determining member and an outer shape determining member; 
           [0038]      FIG. 3  is a plan view of a detailed configuration example of a molten metal cooler; 
           [0039]      FIG. 4  is a plan view of another detailed configuration example of the molten metal cooler; 
           [0040]      FIG. 5  is a sectional view of a free casting apparatus according to a second example embodiment of the invention; 
           [0041]      FIG. 6  is a sectional view of a free casting apparatus according to a third example embodiment of the invention; and 
           [0042]      FIG. 7  is a sectional view of a free casting apparatus according to a fourth example embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0043]    Hereinafter, specific example embodiments to which the invention has been applied will be described in detail with reference to the accompanying drawings. However, the invention is not limited to these example embodiments. Also, the description and the drawings are simplified as appropriate to clarify the invention. Terms such as “top-bottom direction” and “left-right direction” and the like match the top-bottom and left-right directions in the drawings. 
       First Example Embodiment 
       [0044]    First, a free casting apparatus (up-drawing continuous casting apparatus) according to a first example embodiment of the invention will be described with reference to  FIG. 1 .  FIG. 1  is a sectional view of the free casting apparatus according to the first example embodiment. As shown in  FIG. 1 , the free casting apparatus according to the first example embodiment includes a molten metal holding furnace  101 , an inner shape determining member  102   a,  an outer shape determining member  102   b,  support rods  103  and  104 , an actuator  105 , a cooling gas nozzle  106 , a molten metal cooler  107 , a coolant conduit  108 , and an actuator  109 . 
         [0045]    The molten metal holding furnace  101  holds molten metal M 1  such as aluminum or an aluminum alloy, for example, and keeps it at a predetermined temperature. 
         [0046]    In the example in  FIG. 1 , molten metal M 1  is not replenished into the molten metal holding furnace  101 , so the surface of the molten metal M 1  (i.e., the molten metal level) drops as casting proceeds. However, molten metal may also be instantly replenished into the molten metal holding furnace  101  during casting such that the molten metal level is kept constant. Naturally, the molten metal M 1  may be another metal or alloy other than aluminum. 
         [0047]    The inner shape determining member  102   a  and the outer shape determining member  102   b  are made of ceramic or stainless steel, for example, and are arranged near the molten metal surface. In the example shown in  FIG. 1 , the inner shape determining member  102   a  and the outer shape determining member  102   b  are arranged contacting the molten metal surface. However, the inner shape determining member  102   a  and the outer shape determining member  102   b  may also be arranged with a main surface thereof that is on the lower side (i.e., the molten metal side) not contacting the molten metal surface. More specifically, a predetermined gap (such as approximately 0.5 mm) may be provided between the molten metal surface and the lower-side main surface of both the inner shape determining member  102   a  and the outer shape determining member  102   b.    
         [0048]    Moreover, the inner shape determining member  102   a  determines the inner shape of a casting M 3 , and the outer shape determining member  102   b  determines the outer shape of the casting M 3 . The casting M 3  shown in  FIG. 1  is a hollow casting (i.e., a pipe) with a tube-shaped cross-section in the left-right direction (hereinafter referred to as “transverse section”). That is, more specifically, the inner shape determining member  102   a  determines an inner diameter of the transverse section of the casting M 3 , and the outer shape determining member  102   b  determines an outer diameter of the transverse section of the casting M 3 . 
         [0049]      FIG. 2  is a plan view of the inner shape determining member  102   a  and the outer shape determining member  102   b.  Here, the sectional view of the inner shape determining member  102   a  and the outer shape determining member  102   b  in  FIG. 1  corresponds to the sectional view taken along line I-I in  FIG. 2 . As shown in  FIG. 2 , the outer shape determining member  102   b  has a rectangular planar shape, for example, and has a circular open portion in the center portion. The inner shape determining member  102   a  has a circular planar shape, for example, and is arranged in the center portion of the open portion of the outer shape determining member  102   b.  A gap between the inner shape determining member  102   a  and the outer shape determining member  102   b  is a molten metal passage portion  102   c  through which molten metal passes. In this way, the connecting member  102  is formed by the inner shape determining member  102   a,  the outer shape determining member  102   b,  and the molten metal passage portion  102   c.    
         [0050]    As shown in  FIG. 1 , the molten metal M 1  is drawn up following the casting M 3  by the surface tension and the surface film of the molten metal, and passes through the molten metal passage portion  102   c.  Here, the molten metal that is drawn up from the molten metal surface following the casting M 3  by the surface film and the surface tension of the molten metal will be referred to as “retained molten metal M 2 ”. Also, the interface between the casting M 3  and the retained molten metal M 2  is a solidification interface. 
         [0051]    The support rod  103  supports the inner shape determining member  102   a  and the support rod  104  supports the outer shape determining member  102   b.  The positional relationship between the inner shape determining member  102   a  and the outer shape determining member  102   b  is able to be maintained by these support rods  103  and  104 . Here, having the support rod  103  be a pipe structure, flowing cooling gas through the support rod  103 , and moreover, providing blow holes in the inner shape determining member  102   a,  enables the casting M 3  to be cooled from the inside as well. 
         [0052]    The support rods  103  and  104  are both connected to the actuator  105 . This actuator  105  enables the support rods  103  and  104  to move in the top-bottom direction (the perpendicular direction) and the left-right direction, while maintaining the positional relationship between the inner shape determining member  102   a  and the outer shape determining member  102   b.  According to this kind of structure, the inner shape determining member  102   a  and the outer shape determining member  102   b  are able to be moved downward as the molten metal level drops as casting progresses. Also, the inner shape determining member  102   a  and the outer shape determining member  102   b  are able to be moved in the left-right direction, so the shape of the casting M 3  in the longitudinal direction is able to be changed freely. 
         [0053]    A cooling gas nozzle (a cooling portion)  106  is used to spray cooling gas (e.g., air, nitrogen, argon, or the like) at the casting M 3  to cool the casting M 3 . The casting M 3  is cooled by the cooling gas while being drawn up by a drawer, not shown, that is connected to a starter ST. Accordingly, the retained molten metal M 2  near the solidification interface solidifies sequentially, thus forming the casting M 3 . Here, in order to increase the heat removal from the casting M 3  and thus increase the casting speed, the temperature of the cooling gas is preferably made as low as possible. For example, an extremely low temperature gas such as cooling gas that has been cooled by liquefied, gas or cooling gas of liquefied gas (e.g., liquid nitrogen or liquid argon) has been vaporized may be used. 
         [0054]    The molten metal cooler (a molten metal cooling portion)  107  is designed to lower the temperature of the molten metal M 1  positioned directly below the inner shape determining member  102   a  and the outer shape determining member  102   b.  Coolant is circulated through the molten metal cooler  107  only when the temperature of the molten metal M 1  is to be lowered. The provision of the molten metal cooler  107  is one characteristic of the free casting apparatus according to this example embodiment. 
         [0055]    The coolant conduit  108  introduces the coolant into the molten metal cooler  107 , circulates the coolant through the molten metal cooler  107 , and leads the coolant that has removed the heat from the molten metal M 1  out of the molten metal cooler  107 . Also, the coolant conduit  108  supports the molten metal cooler  107 . The coolant is not particularly limited, but from the viewpoint of safety, cooling gas (e.g., air, nitrogen, argon, or the like) is preferable. Also, as a method for circulating the coolant, a suction-type method is more preferable than a pressure-type method from the viewpoint of safety. 
         [0056]    The material of the molten metal cooler  107  and the coolant conduit  108  is not particularly limited. For example, the material may be ceramic or stainless steel. Also, when stainless steel is used, it is preferable to prepare against molten metal loss, e.g., to wrap heat-resistant tape around the portion that contacts the molten metal M 1 . 
         [0057]      FIG. 3  is a plan view of a detailed configuration example of the molten metal cooler  107 . In  FIG. 3 , the inner shape determining member  102   a  and the support rod  103  are both shown by dotted lines to facilitate understanding of the planar positional relationship. The molten metal cooler  107  shown in  FIG. 3  is formed by a single coiled pipe. That is, the molten metal cooler  107  and the coolant conduit  108  are integrally formed. As shown in  FIG. 3 , a circular open portion is formed in the center portion of the molten metal cooler  107 . The support rod  103  passes through this open portion. This kind of structure inhibits interference between the support rod  103  and the molten metal cooler  107 . 
         [0058]      FIG. 4  is a plan view of another detailed configuration example of the molten metal cooler  107 . In  FIG. 4  as well, the inner shape determining member  102   a  and the support rod  103  are both shown by dotted lines to facilitate understanding of the planar positional relationship. The molten metal cooler  107  shown in  FIG. 4  is formed by a single winding pipe (the entire pipe is serpentine-like), with linear portions  107   a  and U-shaped portions  107   b  alternately repeating. That is, the molten metal cooler  107  and the coolant conduit  108  are integrally formed. As shown in  FIG. 4 , at the center portion of the molten metal cooler  107 , the interval between two adjacent, linear portions  107   a  is larger, and the support rod  103  passes through here. This kind of structure inhibits interference between the support rod  103  and the molten metal cooler  107 . The structure of the molten metal cooler  107  shown in  FIGS. 3 and 4  is only one example. Various other configuration examples are also possible. 
         [0059]    The coolant conduit  108  is connected to the actuator  109 . As shown in  FIG. 1 , the actuator  109  enables the molten metal cooler  107  to move in a top-bottom direction in the molten metal M 1 . The molten metal cooler  107  is also able to be moved in the left-right direction to conform to the inner shape determining member  102   a  and the outer shape determining member  102   b.    
         [0060]    When the temperature of the molten metal M 1  positioned directly below the inner shape determining member  102   a  and the outer shape determining member  102   b  is to be lowered, coolant may be circulated inside the molten metal cooler  107 , and the molten metal cooler  107  may be raised so that it moves closer to the inner shape determining member  102   a  and the outer shape determining member  102   b.  On the other hand, in any other case, circulation of the coolant in the molten metal cooler  107  may be stopped, and the molten metal cooler  107  may be lowered so that it moves away from the inner shape determining member  102   a  and the outer shape determining member  102   b.    
         [0061]    Next, the effects of the molten metal cooler  107  will be described in detail. The temperature of the molten metal M 1  is always maintained at a predetermined appropriate temperature by the molten metal holding furnace  101 . Here, the appropriate temperature is a temperature for keeping the solidification interface at an appropriate height. The height of the solidification interface is maintained by a balance between heat removal from the casting M 3  and up-drawing speed. For example, when the thickness of the casting M 3  is thick during casting, the heat capacity of the retained molten metal M 2  increases, so the balance becomes off, the position of the solidification interface rises, and the desired shape becomes difficult to obtain. That is, moldability deteriorates. 
         [0062]    At this time, in order to return the position of the solidification interface to the original appropriate height, if the heat removal from the casting M 3  is unable to be increased, the casting speed must be slowed or the temperature of the molten metal M 1  must be lowered. In order to lower the temperature of the molten metal M 1 , all that need be done is to lower the set temperature of the molten metal holding furnace  101 . However, it takes time for all of the molten metal M 1  to actually drop to the set temperature. With the free casting apparatuses until now, the casting speed had to be slowed until the temperature of all of the molten metal M 1  dropped to the set temperature. 
         [0063]    In contrast, the free casting apparatus according to this example embodiment is provided with the molten metal cooler  107 , so the temperature of the molten metal M 1  can be lowered in a short period of time. In particular, the molten metal cooler  107  is positioned directly below the inner shape determining member  102   a  and the outer shape determining member  102   b,  so the temperature of only the molten metal M 1  near the inner shape determining member  102   a  and the outer shape determining member  102   b  (or more specifically, directly below the inner shape determining member  102   a  and the outer shape determining member  102   b ) is able to be lowered in a short period of time. Therefore, the casting speed does not need to be slowed, so the casting speed can be faster than it is with the free casting apparatuses until now. As a result, the casting time is shorter, so productivity is improved. 
         [0064]    Next, the free casting method according to the first example embodiment will be described with reference to  FIG. 1 . First, the starter ST is lowered so that it passes through the molten metal passage portion  102   c  between the inner shape determining member  102   a  and the outer shape determining member  102   b,  and the tip end of the starter ST is immersed in the molten metal M 1 . 
         [0065]    Next, the starter ST starts to be drawn up at a predetermined speed. Here, when the starter ST separates from the molten metal surface, the retained molten metal M 2  that follows the starter ST and is drawn up from the molten metal surface by the surface film and surface tension is formed. As shown in  FIG. 1 , the retained molten metal M 2  is formed in the molten metal passage portion  102   c  between the inner shape determining member  102   a  and the outer shape determining member  102   b.  That is, the inner shape determining member  102   a  and the outer shape determining member  102   b  give the retained molten metal M 2  its shape. 
         [0066]    Next, the starter ST is cooled by cooling gas blown from the cooling gas nozzle  106 , so the retained molten metal M 2  solidifies sequentially from the upper side toward the lower side, thus forming the casting M 3 . In this way, the casting M 3  is able to be continuously cast. 
       Second Example Embodiment 
       [0067]    Next, a free casting apparatus according to a second example embodiment of the invention will be described with reference to  FIG. 5 .  FIG. 5  is a sectional view of the free casting apparatus according to the second example embodiment. As shown in  FIG. 5 , the free casting apparatus according to the second example embodiment includes a molten metal holding furnace  101 , an inner shape determining member  102   a,  an outer shape determining member  102   b,  support rods  103  and  104 , an actuator  105 , a cooling gas nozzle  106 , a molten metal cooler  107 , a coolant conduit  108 , an actuator  109 , a partition wall  110 , and an ambient temperature regulating portion  111 . That is, the partition wall  110  and the ambient temperature regulating portion  111  are added to the free casting apparatus according to the first example embodiment shown in  FIG. 1 . The other structure is the same as it is in the first example embodiment, so a description thereof will be omitted. 
         [0068]    As shown in  FIG. 5 , with the free casting apparatus according to the second example embodiment, the molten metal M 1  and the casting M 3  are housed in a space partitioned off by the partition wall  110 . Also, the ambient temperature regulating portion  111  is provided on a ceiling portion of the partition wall  110 . 
         [0069]    According to this kind of structure, the temperature in the space partitioned off by the partition wall  110  is maintained at a predetermined temperature (such as 25° C. for example) by the ambient temperature regulating portion  111 . Because the temperature of the atmosphere of the molten metal M 1  and the casting M 3  is kept constant, the quality of the casting M 3  is able to be more stable than it is with the free casting apparatus according to the first example embodiment. Also, by keeping the temperature of the atmosphere at 25° C., for example, the temperature of the atmosphere drops farther than it does when the temperature of the atmosphere is not controlled, so the casting speed is able to be faster than is with the free casting apparatus according to the first example embodiment. The location where the ambient temperature regulating portion  111  is arranged is not particularly limited. Also, as shown in  FIG. 5 , an air flow port  110   a  may be provided in an upper portion of the partition wall  110  so that heated air trapped inside the partitioned space is able to escape. 
       Third Example Embodiment 
       [0070]    Next, a free casting apparatus according to a third example embodiment of the invention will be described with reference to  FIG. 6 .  FIG. 6  is a sectional view of the free casting apparatus according to the third example embodiment. As shown in  FIG. 6 , the free casting apparatus according to the third example embodiment includes a molten metal holding furnace  101 , an inner shape determining member  102   a,  an outer shape determining member  102   b,  support rods  103  and  104 , an actuator  105 , a cooling gas nozzle  106 , and a coolant conduit  112 . That is, the molten metal cooler  107 , the coolant conduit  108 , and the actuator  109  in the free casting apparatus according to the first example embodiment shown in  FIG. 1  are not provided, and instead, the coolant conduit  112  is provided. The other structure is the same as it is in the first example embodiment, so a description thereof will be omitted. 
         [0071]    As shown in  FIG. 6 , the free casting apparatus according to the third example embodiment includes the coolant conduit (a cooling mechanism)  112  that is wound in a helical shape around a starter ST. That is, the free casting apparatus according to the third example embodiment has a cooling mechanism that is integrated with the starter ST. According to this kind of structure, the starter ST is cooled. The coolant is not particularly limited, but cooling gas (e.g., air, nitrogen, argon, or the like), or cooling water may be used, for example. Cooling the starter ST enables heat removal from the casting M 3  to be increased and casting speed to be faster while retaining good moldability. 
         [0072]    Of course, the casting speed may be increased even more by combining the first example embodiment with the third example embodiment, or the second example embodiment with the third example embodiment. 
       Fourth Example Embodiment 
       [0073]    Next, a free casting apparatus according to a fourth example embodiment of the invention will be described with reference to  FIG. 7 .  FIG. 7  is a sectional view of the free casting apparatus according to the fourth example embodiment. As shown in  FIG. 7 , the free casting apparatus according to the fourth example embodiment includes a molten metal holding furnace  101 , an outer shape determining member  102   b,  a support rod  104 , an actuator  105 , and a cooling gas nozzle  106 . That is, the inner shape determining member  102   a,  the support rod  103 , and the coolant conduit  112  in the free casting apparatus according to the third example embodiment shown in  FIG. 6  are not provided. On the other hand, the starter ST itself is a coolant conduit (a cooling mechanism). That is, the free casting apparatus according to the fourth example embodiment is also provided with a cooling mechanism that is integrated with the starter ST. The other structure is the same as it is in the third example embodiment, so a description thereof will be omitted. 
         [0074]    As shown in  FIG. 7 , the casting M 3  cast with the free casting apparatus according to the fourth example embodiment is a solid structure (a rod), not a hollow structure (a pipe). Therefore, the inner shape determining member  102   a  is not used. Only the outer shape determining member  102   b  according to the example embodiment described above is used. In this case, the open portion provided in the outer shape determining member  102   b  as it is serves as a molten metal passage portion  102   c.    
         [0075]    With the free casting apparatus according to the fourth example embodiment, the starter ST itself is the coolant conduit, so the starter ST is cooled. The coolant is not particularly limited, but cooling gas (e.g., air, nitrogen, argon, or the like) may be used, for example. Also, the flow rate of the coolant may be controlled at the start of casting and during casting. More specifically, the flow rate of the coolant may be lower at the start of casting than it is during casting. Furthermore, during casting (i.e., after casting has progressed to some extent), cooling water may also be used. Also, cooling gas may be used at the start of casting, and cooling water may be used during casting. 
         [0076]    With the free casting apparatus according to the fourth example embodiment, cooling the starter ST enables heat removal from the casting M 3  to be increased and casting speed to be faster, just like the third example embodiment. Also, because the starter ST is cooled, material with a lower melting point than the molten metal temperature may be used as the starter ST. Furthermore, the coolant temperature on the inlet side and the coolant temperature on the outlet side may be monitored and fed back to the casting control. After casting, heat treatment for texture control may be performed by circulating heat treating oil instead of coolant through the starter ST. 
         [0077]    Also, a normal starter ST is removed after casting, but the starter ST according to the fourth example embodiment is able to be used as it is as a product. For example, pipe for a heat exchanger may be used as the normal starter ST. Furthermore, an even more complicated cooling circuit may also be used as the starter ST. Also, a casting that includes a pipe therein can also be formed by immersing the starter ST in the molten metal. 
         [0078]    Of course, the casting speed may be increased even more by combining the first example embodiment with the fourth example embodiment, or the second example embodiment with the fourth example embodiment. 
         [0079]    The invention is not limited to the example embodiments described above, and may be modified as appropriate.