JP4314207B2 - Casting method and casting apparatus - Google Patents

Description

  The present invention relates to a casting method and apparatus suitable for casting an alloy that easily segregates during solidification.

For alloys that are susceptible to weight segregation because they contain additive elements with a large specific gravity difference, and alloys that tend to segregate during solidification, segregation during casting is effectively generated to improve product quality. It is desired to prevent it. In particular, the segregation is likely to occur in Mg alloys and other light alloys.
The segregation of alloying elements that occur during casting can be achieved by lowering the casting temperature to shorten the time until solidification, thereby reducing crystal grain growth and preventing precipitation of high specific gravity phases or elements with high atomic weight. Conceivable. However, in actual casting, it is difficult to substantially lower the casting temperature, taking into account the flowability of the thin-walled portion and the complicated-shaped portion. In addition, in a simple shape such as an ingot, the casting temperature can be lowered, but since such a thing is generally thick, even if the casting temperature is lowered somewhat, the solidification time is long and segregation inevitably occurs.

In addition, methods for reducing segregation indirectly by reducing segregation during casting or making the structure finer have been proposed (for example, Patent Documents 1 and 2).
The method disclosed in Patent Document 1 solidifies in a horizontal direction in a directional solidification furnace having a cooling plate and a heating furnace, and slowly rotates around a horizontal axis. This casting method reduces casting defects such as nests and segregation.
In addition, the method disclosed in Patent Document 2 is such that a mold is placed on a chill plate (water-cooled plate), and the mold is rotated / reversed in small increments or stopped in the same direction for the purpose of producing a fine equiaxed crystal structure. Is a casting method in which horizontal vibration is repeatedly applied.
JP 2000-343204 A JP 2002-331354 A

  However, the casting method disclosed in Patent Document 1 is a method that can be manufactured without casting defects such as shrinkage cavities only when a high temperature gradient is applied using an expensive apparatus using a cooling plate and a heating furnace. It is difficult to apply to a general low-cost light alloy casting method. Also, it is a method of rotating very slowly so as not to break the directional solidification structure and single crystal structure, and it is effective only in the case of a very slow solidification rate that solidifies while heating the mold. Cannot be obtained.

  In addition, the casting method disclosed in Patent Document 2 uses a chill plate and a heating furnace to maintain soundness in order to eliminate microporosity, and occupies this device for a long time until the end of solidification. Therefore, the cost becomes high. In addition, when such a temperature gradient is made large in the vertical direction, there is a high possibility that component segregation in the vertical direction occurs although there is a miniaturization effect. In addition to these methods, a method for homogenization by stirring the molten metal using an electromagnetic stirrer has been proposed, but there is a problem that the equipment investment is enormous and the manufacturing cost is increased.

  The present invention makes it possible to give a sufficient stirring force to the molten metal without incurring costs such as the above-mentioned facilities and man-hours, thereby preventing segregation and obtaining a cast product with excellent quality. An object of the present invention is to provide a casting method and a casting apparatus. Another object of the present invention is to prevent the coarsening of the crystal structure. In particular, it is an object of the present invention to provide a casting method and a casting apparatus that are most suitable for the production of thick cast products that are prone to segregation and ingots for plastic working (for extrusion, forging and rolling).

That is, of the casting method of the present invention, an invention according to claim 1, further comprising a feeder head portion inner surface shape is made of a non-rotating body shape, the mold containing the molten magnesium alloy, solidifying the molten magnesium alloy While rotating the vertical axis in a certain direction for a predetermined time, and reaching the predetermined time, the mold is rotated in a direction opposite to the rotation direction for a predetermined time, and the forward and reverse rotations are repeated. The magnesium alloy melt is solidified.

The invention of the casting method according to claim 2 is a shape in which the molten magnesium alloy is accommodated in the inner surface of the feeder part provided in the mold and the stirring force is applied to the molten magnesium alloy when the mold is rotated. stirring portion but granted, may be provided prior to accommodation of the molten magnesium alloy, the mold containing the molten magnesium alloy, in a predetermined direction by the rotation axis and the vertical axis while solidifying the molten magnesium alloy The mold is rotated for a predetermined time, and after reaching the predetermined time, the mold is rotated for a predetermined time in a direction opposite to the rotation direction, and the forward and reverse rotation is repeated to solidify the magnesium alloy melt. .

The invention of the casting method according to claim 3 is the invention according to claim 2, characterized in that the inner surface shape of the feeder part is a non-rotating body shape .

  According to a fourth aspect of the present invention, there is provided a casting method according to any one of the first to third aspects, wherein an inner surface shape of the casting portion of the mold is a rotating body shape.

  The invention of the casting method according to claim 5 is the invention according to any one of claims 1 to 4, wherein the rotation of the mold is such that the peripheral speed of the outermost metal melt is 400 to 1000 mm / second, The rotation time is 5 to 60 seconds.

  According to a sixth aspect of the present invention, there is provided a casting method according to any one of the first to fifth aspects, wherein the normal and reverse rotations of the mold are performed as follows: a solidification temperature of a molten metal + 200 ° C. or less; It is characterized in that it is carried out within the range of ℃ or higher.

According to a seventh aspect of the present invention, there is provided a casting apparatus having a feeder having a non-rotating body shape on the inner surface, a mold for containing and melting the magnesium alloy melt , and the mold having a vertical axis as a rotation axis. A rotating device that can be driven to rotate in the reverse direction, and continuously rotating the mold at a predetermined rotation speed in a predetermined direction for a predetermined time, and after reaching the predetermined time, a predetermined rotation in a direction opposite to the rotation direction And a rotation control unit that controls the rotating device to repeat the operation of continuously rotating at a speed for a predetermined time.

According to an eighth aspect of the present invention, there is provided a casting apparatus according to claim 8, wherein when the molten magnesium alloy is accommodated and the mold is rotated, a stirring portion to which a stirring force is applied to the molten magnesium alloy is provided. A mold having a feeder part provided prior to housing the molten metal , containing the molten magnesium alloy, and solidifying the mold; and a rotating device capable of rotationally driving the mold in the forward and reverse directions with the vertical axis as a rotational axis. The mold is continuously rotated in a predetermined direction at a predetermined rotation speed for a predetermined time, and after reaching the predetermined time, an operation of continuously rotating the mold in a direction opposite to the rotation direction at a predetermined rotation speed for a predetermined time is repeated. And a rotation control unit that controls the rotation device.
The invention of the casting apparatus according to claim 9 is the invention according to claim 8, wherein the inner surface shape of the feeder is a non-rotating body shape.

According to a tenth aspect of the present invention, there is provided a casting apparatus according to the eighth or ninth aspect , wherein the stirring portion is a ridge formed on the inner surface of the feeder portion along the vertical direction.

An invention of a casting apparatus according to an eleventh aspect is the invention according to the tenth aspect, characterized in that the protrusion has an upper end height protruding above the gate.

According to a twelfth aspect of the present invention, in the invention according to the tenth or eleventh aspect , the protrusions are provided in a number of 1 to 4 at intervals in the circumferential direction. .

That is, according to the present invention, by repeatedly switching between continuous rotation and forward / reverse rotation of the mold, the molten metal in the mold is oscillated without making the magnesium alloy molten liquid surface undulate, and the stirring is actively performed. Done. As a result, the temperature distribution of the molten metal in the mold is made uniform, and the temperature of the molten metal is uniform except for the vicinity of the mold wall where the influence of cooling by the mold is large. Solidification does not start immediately after pouring, but the temperature of the liquid phase that has been continuously stirred is lowered, and solidification proceeds only after the solidification start temperature is reached. Therefore, the solidification is solidified in a state where there is little time difference from the solidification of the outer peripheral portion to the completion of the solidification of the central portion, and there are very few segregated substances that tend to collect in the final solidified portion. Even if partial segregation occurs, the generation of crystal nuclei is promoted by stirring to reduce the crystal structure, and the segregation occurring at the crystal grain boundaries is finely dispersed as compared with the usual and the influence on strength deterioration is reduced. In addition to segregation due to melting point differences and solid solubility between the grain boundaries and dendrites (dendritic crystals) as described above, there is little sedimentation of phases containing additive elements with a large atomic weight because they solidify while stirring. Even for weight segregation, segregation can be reduced by the stirring effect and solidification in a short time. In this way, by eliminating the partially low strength structure due to segregation, it is possible to produce a stable and good material with little variation in strength. In addition, secondary effects such as strength improvement by refining crystal grains accompanying stirring can be expected.

  On the other hand, when there is no agitation, the molten metal in the mold has a temperature gradient from the outer periphery of the cast product to the center of the casting, and solidification progresses immediately after pouring, so the time from the outer periphery to the center of solidification is A big difference occurs. Therefore, the structure tends to become coarse as it slowly solidifies from the mold wall toward the center, and as a result, segregation increases with a long solidification time.

  It should be noted that the above effect is usually more effective for a large-volume casting having a longer solidification time. In the case of a large-volume casting, in order to efficiently stir at a low rotation, it is desirable to provide a stirring portion provided with a shape capable of stirring the molten metal on the inner surface of the feeder portion. The stirring unit may be any member as long as it can give a stirring effect to the molten metal, and can be constituted by a protrusion, a protrusion, a stirring plate, and the like. More effectively, it is effective to provide a protrusion along the longitudinal direction in the feeder part. It is desirable that the protrusion protrudes about 10 to 25 mm from the liquid phase part of the gate after casting. A plurality of protrusions can be provided at intervals in the circumferential direction. Preferably, equiangular spacing is desirable, 1-4. When the number is increased, the stirring effect is lowered, so 4 or less is desirable. The protrusions only need to be along the vertical direction, and may be provided to be inclined with respect to the top and bottom in addition to the vertical direction, and are not limited to straight ones.

  Moreover, if the inner surface of the feeder part has a non-rotating body shape such as a polygon, when the mold rotates, turbulent flow is likely to occur inside the feeder part, and the stirring effect is enhanced. On the other hand, in the casting part, since it is necessary to flow as a whole, it is desirable that the inner surface has a rotating body shape.

In addition, in the rotation of the mold, it is desirable that the peripheral speed of the outermost periphery of the magnesium alloy melt is in the range of 400 to 1000 mm / second, and the switching interval between forward and reverse rotation is 5 to 60 seconds. This is because if the peripheral speed is less than 300 mm / second, the molten metal in the vicinity of the mold wall, which has a large influence of cooling, cannot be sufficiently stirred, while a peripheral speed exceeding 1500 mm / second is applied. In addition, since the stirring action is too strong and the liquid phase surface undulates and there is a problem such as a hot water boundary and gas entrainment, it is desirable to rotate the mold so as to be within the above speed range. In addition, if the interval between forward and reverse rotation is less than 5 seconds, the rotation is switched too frequently and the flow rate is not sufficiently increased. On the other hand, if it exceeds 60 seconds, the molten metal continues to rotate in a steady state. Since the stirring action cannot be obtained efficiently, the above switching interval is desirable.

  Further, it is desirable that the mold is rotated up to the temperature range of solidification temperature + 200 ° C. to solidification temperature −50 ° C. after the start of casting. When the rotation of the mold is completed at a temperature higher than the solidification temperature, the temperature distribution of the molten metal becomes non-uniform and segregation is likely to occur. On the other hand, even if the rotation of the mold is continued to a temperature lower than the solidification temperature, the effect of preventing segregation does not increase any more and is useless. Therefore, it is desirable to end the rotation of the mold within the above temperature range.

  Switching between the rotation of the mold and the forward / reverse rotation can be performed by a rotation control unit that controls a rotating device constituted by a motor or the like. The rotation control unit can be configured by a control circuit, a CPU that operates according to a program, and the like.

The present invention is suitable for casting of an alloy that is likely to cause segregation during weight segregation or solidification, and is particularly intended for Mg alloys including zinc, rare earth metals, and other light alloys . Particularly suitable for thick casts or billets and ingots for extrusion, rolling and forging .

As described above, according to the casting method of the present invention, includes a feeder head portion inner surface shape is made of a non-rotating body shape, the mold containing the molten magnesium alloy, while solidifying the molten magnesium alloy ordinate And rotating the mold for a predetermined time in the direction opposite to the direction of the rotation for a predetermined time, and repeating the forward and reverse rotations to repeat the rotation of the magnesium alloy. Since the molten metal is solidified, uneven precipitates are reduced as much as possible, and a fine homogeneous structure is obtained, and a metal material excellent in ductility and strength can be obtained. Further, according to another casting method of the present invention, when the molten metal is accommodated in the inner surface of the feeder part provided in the mold and the mold is rotated, a stirring force is applied to the molten magnesium alloy inside. gives the stirring section shape is imparted, may be provided prior to accommodation of the molten magnesium alloy, the mold containing the molten magnesium alloy, certain of the vertical axis to the rotary shaft while solidifying the molten magnesium alloy After rotating for a predetermined time in the direction and reaching the predetermined time, the mold is rotated for a predetermined time in a direction opposite to the direction of rotation, and the forward and reverse rotation is repeated to solidify the magnesium alloy melt. In addition, it is possible to obtain a metal material excellent in ductility and strength by reducing uneven precipitates as much as possible and obtaining a fine and homogeneous structure.

In addition, according to the casting apparatus of the present invention, the mold has a feeder portion whose inner surface shape is a non-rotating body shape, accommodates and solidifies the magnesium alloy molten metal , and the mold is aligned with the vertical axis as the rotation axis. A rotating device that can be driven to rotate in the reverse direction, and continuously rotating the mold at a predetermined rotation speed in a predetermined direction for a predetermined time, and after reaching the predetermined time, a predetermined rotation in a direction opposite to the rotation direction Since the rotation control unit that controls the rotation device so as to repeat the operation of continuously rotating at a speed for a predetermined time is provided, it is possible to reliably obtain the above-described operation by controlling the rotation of the mold. Further, according to another casting apparatus of the present invention, when the magnesium alloy molten metal is accommodated and the mold is rotated, the stirring unit provided with a shape that gives stirring force to the magnesium alloy molten metal is provided to the mold. has a feeder head portion provided prior to receiving the molten magnesium alloy, and the mold to solidify to accommodate the molten magnesium alloy, rotating drivable rotating vertical axis of the mold in the forward and reverse direction with the rotation axis An operation of continuously rotating the apparatus and the mold at a predetermined rotation speed in a predetermined direction for a predetermined time and continuously rotating at a predetermined rotation speed in a direction opposite to the rotation direction after reaching the predetermined time. Since the rotation control unit for controlling the rotating device is provided so as to repeat the above, similarly, the above-described operation can be reliably obtained by controlling the rotation of the mold.

Below, the casting apparatus of this invention is demonstrated based on FIG.
The cylindrical mold 1 has a feeder 2 made of a box shape (square tube) with a large inner dimension at the top, and a carbon plate 3 is attached to the inner surface of the feeder 2 to prevent shrinkage. ing.
The mold 1 is installed on a rotating device 6 covered with a heat insulating material or a water cooling structural member (not shown), and the mold 1 can be rotated by the rotating device 6. The rotating device 6 includes a turntable 60 on which the mold 1 is installed. A motor 61 is attached to the turntable 60 via a gear (not shown), and the turntable 60 is rotationally driven by the motor 61. The motor 61 is capable of adjusting the rotation speed and switching the rotation direction.

  The rotation device 6 is connected to a rotation control unit 7 including a CPU 70 and a drive circuit 71, and the rotation control unit 7 further sets a rotation speed of the mold and a forward / reverse rotation switching interval. 72 is provided. The rotation control unit 7 can suitably set 0 to 100 rpm as the rotation speed and 1 to 300 seconds as the switching interval. The rotation setting unit may be set so as to input an appropriate value by an operator's operation, and necessary data is stored in advance in a storage means such as a nonvolatile memory or an HDD. May be configured to read out.

Next, the operation of the casting apparatus will be described.
First, the Mg alloy is melted in a melting furnace 10 such as a crucible, and the magnesium alloy molten metal 11 is poured into the mold 1 through the tundish 12. The magnesium alloy molten metal 11 is accommodated up to a predetermined height of the feeder 2. Next, a control command is given from the CPU 70 to the drive circuit 71 based on the rotation speed and rotation switching interval set in advance by the setting unit 72, and a control signal is given to the rotating device 6. Thereby, the rotating device 6 rotates the mold 1 in accordance with the control command. In the mold 1 rotating at a suitable rotational speed, the stirring temperature is given so that the peripheral speed of the outermost periphery of the molten magnesium alloy is 400 to 1000 mm / second, and the temperature of the molten metal is made uniform. An appropriate turbulent flow is generated in the hot water part 2 to enhance the stirring action. At this time, the undulation of the liquid surface is suppressed by a suitable rotational speed. Moreover, the rotation direction is switched at an optimal switching interval (5 to 60 seconds) immediately before the rotation of the magnesium alloy 11 is stabilized by the rotation of the mold 1, and the magnesium alloy melt 11 is effectively stirred. According to the above, a cast product having a finely homogenized structure with little segregation can be obtained.

  In addition, in the said embodiment, although the special structure is not provided in the feeder's inner surface, as shown in FIG. 2, the stirring part 8 which gives the stirring action with respect to the molten metal 11 may be provided in the inner surface of the feeder part 2a. Is possible. In this embodiment, the stirring unit 8 is formed as a protrusion (rib) extending in the vertical direction. Further, as shown in FIG. 2 (b), the upper end position of the stirring unit 8 is preferably projected on the liquid surface when the molten metal is accommodated in the mold, and is preferably equiangularly spaced in the circumferential direction. 1-4 are installed so that it may have. However, the present invention is not limited to a specific number.

(Preliminary experiment)
Next, in order to confirm the effect of stirring according to the present invention, the behavior of beaker water and wax particles suspended in the beaker (specific gravity 0.99) was observed in a preliminary experiment. As shown in FIG. 3, a beaker 32 in which 100 wax particles 31 were suspended in water 30 was placed on a turntable 33 and rotated.
The rotation was carried out by changing the rotation speed as shown in Table 1, and the inversion interval was constant (10 seconds).
As a result, by adding inversion, a good stirring effect was obtained at a predetermined rotational speed. However, in this state, it is not possible to obtain a large stirring force such that the wax sinks. Therefore, the rib 32a as shown in FIG. 4 is installed on the inner surface of the beaker 32 so as to be positioned near the liquid surface. The wax behavior was observed by changing the number of ribs and the number of rotations. FIG. 5 shows the sedimentation depth of the wax that sinks to the deepest with the depth from the liquid surface to the bottom being 100%, and FIG. 6 shows the ratio to the total amount of wax that has settled from the liquid surface. As a result, the higher the rotational speed, the greater the stirring force, and the number of ribs peaked at 2 and the stirring effect decreased before and after. In addition, the stirring force becomes the highest during inversion. However, if the rotational speed is increased too much, the fluctuation of water increases, and there is a possibility of undulations and scattering during actual casting.
In the case of an actual large cast product, if the peripheral speed is at the same level, low rotation is possible, and if the outer diameter of the cast product is 30 rpm at φ300 mm and about 15 rpm at φ600 mm, a sufficient effect is obtained.

Based on the preliminary experiment, an Mg—Zn—RE alloy was cast using the casting apparatus of the above embodiment.
A mild steel mold having an inner diameter of 300 mm and a height of about 1000 mm was placed on the turntable, and the Mg alloy was melted in a melting furnace. The alloy is Y = 6.67 wt%, Zn = 4.91 wt%, La (RE) = l. The alloying elements were adjusted with the goal of 04 wt%. The mold was poured into a mold at a melting temperature of 780 ° C. The turntable was rotated at 30 rpm immediately before pouring, and reversal was repeated every 35 seconds. After casting, rotation was performed for a total of 10 minutes. The inversion time was set to the shortest time when the stirring force became steady, and the inversion time until solidification was taken as much as possible. This is because large agitation occurs during inversion. For comparison, casting without rotation was also performed. The dissolution method and mold shape are the same. The rotation condition 1 was reversed immediately after 35 seconds, and this was repeated, and the rotation condition 2 was stopped once after 30 seconds and turned over for 5 seconds and then reversed and repeated.
About 1 hour after casting, the mold was removed from the apparatus, and the cast product was taken out for component analysis. The result is shown in FIG.

  In the product section, some of the components of the stationary material (x mark) are over on the plus side, but all of the components that are rotationally agitated are within the target range, and good component values are obtained. I understand that. Even if the width of variation is seen, a normal stationary cast material that does not rotate greatly fluctuates, but a material that has been solidified by rotating and stirring has a small fluctuation range and is stable.

Moreover, the difference of the component value of the radial direction of a center part and a surface was confirmed in the rotary stirring material and the stationary casting material. They are shown in FIGS. In the rotary stirrer of FIG. 8, the component values are within the target range in both the vertical direction and the radial direction of the cast product. On the other hand, in the stationary cast material of FIG. 9, the concentration of La, Zn, and Y deviates from the target component as it goes from the bottom of the cast product to the upper side where solidification is slow, and the center portion in the radial direction where solidification is slow. That is, the effect of the present invention by stirring is clear.
The cast structure was also observed. As apparent from the photomicrograph of FIG. 10, the cast product of the invention example that was rotationally stirred under rotational condition 1 had a homogeneous equiaxed crystal structure. On the other hand, as shown in the micrograph of FIG. 11, the cast product of the comparative example cast without being stirred is not an equiaxed crystal and has a direction extending upward from the bottom. is there. Therefore, the crystal grain size was also coarse, and weight segregation and grain boundary segregation were observed. In addition, the said micrograph was typically shown in FIG.
As mentioned above, although this invention was demonstrated based on the said embodiment and Example, this invention is not limited to the said description, Of course, it can change within the scope of the invention.

It is the schematic which shows the casting apparatus of one Embodiment of this invention. It is the schematic which shows the example of a change similarly. It is the schematic which shows the test apparatus used for the Example of this invention. It is the schematic which shows the example of a change similarly. Similarly, it is a graph showing the relationship between the number of ribs and the settling depth. Similarly, it is a graph showing the relationship between the number of ribs and the amount of sedimentation. Similarly, it is a figure which shows distribution of the chemical component of a casting material when the rotation state of a casting_mold | template is changed in the invention example. Similarly, it is a figure which shows distribution of the chemical component of the up-down and radial direction of a casting material when the rotation state of a casting_mold | template is changed in the example of an invention. Similarly, it is a figure which shows distribution of the chemical component of the up-down and radial direction of the casting material of the prior art which does not rotate. Similarly, it is a structure observation photograph of the cast product of the invention example. Similarly, it is a structure observation photograph of a cast product of a conventional example. Similarly, it is the schematic diagram of the structure | tissue observation photograph of the casting of an invention example and a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Feeding part 6 Rotating device 60 Turntable 61 Motor 7 Rotation control part 8 Stirring part 11 Magnesium alloy molten metal

Claims (12)

Has a feeder head portion inner surface shape is made of a non-rotating body shape, the mold containing the molten magnesium alloy, and the rotary shaft is rotated a predetermined time in a predetermined direction a vertical axis while solidifying the molten magnesium alloy, the After reaching a predetermined time, the casting mold is rotated in a direction opposite to the direction of rotation for a predetermined time, and the forward and reverse rotation is repeated to solidify the molten magnesium alloy . The inner surface of the feeder head portion provided in a mold, the stirring section shape is imparted to housing the molten magnesium alloy give stirring force to the inside of the molten magnesium alloy when rotating the said mold, said magnesium alloy Prior to housing the molten metal, the mold containing the molten magnesium alloy was rotated for a predetermined time in a predetermined direction with the vertical axis as a rotation axis while solidifying the molten magnesium alloy , and reached the predetermined time. Thereafter, the casting method is characterized in that the mold is rotated in a direction opposite to the rotation direction for a predetermined time, and the magnesium alloy melt is solidified by repeating the forward and reverse rotations.   The casting method according to claim 2, wherein the inner surface shape of the feeder is a non-rotating body shape.   The casting method according to claim 1, wherein an inner surface shape of the casting portion of the mold is a rotating body shape. The rotation of the casting mold is characterized in that the peripheral speed of the outermost periphery of the molten magnesium alloy is 400 to 1000 mm / second, and the rotation time in one direction is 5 to 60 seconds. Casting method. The forward and reverse rotation of the mold, molten magnesium alloy of solidification temperature + 200 ° C. or less, according to any one of claims 1 to 5, characterized in that to within the solidification temperature of -50 ° C. or more molten magnesium alloy Casting method. A mold having an inner surface shaped as a non-rotating body, containing a molten magnesium alloy , and solidifying the mold; and a rotating device capable of rotating the mold in the forward and reverse directions with the vertical axis as a rotation axis; The mold is continuously rotated in a predetermined direction at a predetermined rotation speed for a predetermined time, and after reaching the predetermined time, an operation of continuously rotating the mold in a direction opposite to the rotation direction at a predetermined rotation speed for a predetermined time is repeated. And a rotation control unit for controlling the rotation device. A mold having a feeder part and containing a molten magnesium alloy, solidifying the mold, a rotating device capable of rotationally driving the mold in the forward and reverse directions with the vertical axis as a rotational axis, and the mold at a predetermined rotational speed. A rotation control unit that continuously rotates in a certain direction for a time, and controls the rotating device to repeat an operation of continuously rotating for a predetermined time at a predetermined rotation speed in a direction opposite to the rotation direction after reaching the predetermined time. And a stirring portion provided with a shape that gives stirring force to the inner magnesium alloy melt as the mold rotates, is provided on the inner surface of the feeder portion.   The casting apparatus according to claim 8, wherein the inner surface shape of the feeder part is a non-rotating body shape.   The casting apparatus according to claim 8 or 9, wherein the agitating part is a protrusion formed on the inner surface of the feeder part along the vertical direction.   The casting apparatus according to claim 10, wherein the protrusion has an upper end height protruding above the gate.   The casting apparatus according to claim 10 or 11, wherein the protrusions are provided in the number of 1 to 4 at intervals in the circumferential direction.