Method for manufacturing stirring bars and aluminum alloy ingots

Abstract

In the ingot manufacturing process, mechanically agitating the molten metal refines the grain size, suppressing the occurrence of abnormal structures, and also reduces macroscopic segregation of solute elements, thereby suppressing casting cracks. [Solution] A method for manufacturing an aluminum alloy ingot, comprising a casting step of rotating a stirring bar 3 in molten aluminum alloy and solidifying the molten metal while agitating it, wherein the casting step involves rotating the stirring bar with a flow straightening plate 32 having a projection on its lower edge positioned between the surface of the molten metal and the rotating blade.

Description

Technical Field

[0001] The present invention relates to a stirrer and a method for manufacturing an aluminum alloy ingot. Specifically, in the process of manufacturing an ingot, by mechanically oscillating the molten metal, macro-segregation of solute elements is reduced, the crystal grain size is refined to suppress the generation of abnormal structures, and ingot cracking can be suppressed. The present invention relates to a stirrer and a method for manufacturing an aluminum alloy ingot that can achieve these effects.

Background Art

[0002] For example, in the case of a sputtering target, it is required that the content of impurities in its chemical composition is low, it does not contain foreign substances such as non-metallic inclusions, the abundance ratio of defects such as voids is low, and its crystal grain size is uniform and fine throughout the sputtering surface. Similar characteristics are also required for the ingot which is the raw material.

[0003] When manufacturing a sputtering target, first, the target metal is melted, the components are adjusted to purify the molten metal, and then it is cast to obtain an ingot which is the raw material. Further, by performing predetermined plastic processing and heat treatment on this ingot, a sputtering target can be obtained.

[0004] Also, the crystal grains of the sputtering target are controlled in the process of performing plastic processing and heat treatment. However, the finer the crystal grain size of the ingot, the easier the control, and cost reduction can also be achieved by simplifying the plastic processing and heat treatment processes.

[0005] Note that the ingot which is the raw material for the sputtering target has a low frequency of generating solidification nuclei during solidification due to its low content of impurities in its chemical composition. Therefore, the crystal grain size tends to be coarse, and the frequency of generating abnormal structures such as feathery crystals is also high. Furthermore, there are strict regulations on the contained components, and the addition of metals and their compounds called grain refinement materials, which are often used in the ingots of general alloys, is not allowed.

[0006] However, it is known that coarse grain size and the presence of abnormal structures in the ingots used as sputtering targets have adverse effects such as poor deformation and uneven structure during the plastic deformation process of the sputtering target, and that they concentrate solidification stress during the solidification process of the ingot, causing ingot cracking. Therefore, in order to improve the quality of sputtering targets, it is necessary to suppress the occurrence of abnormal structures and refine the grain size.

[0007] In casting, when molten metal containing solute elements solidifies, redistribution of the solute occurs, resulting in microscopic and macroscopic segregation of the solute components. Of these, macroscopic segregation of solute components in particular not only deteriorates the properties of the sputtering target but can also cause ingot cracking. Reducing macroscopic segregation of solute elements can increase the success rate of the casting process.

[0008] It is already known that the above problems can be improved by mechanically agitating the molten metal near the solidification interface in the casting process, and one such method is the technology described in Patent Document 1. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2017-94391 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, even when the molten metal is agitated using the technology described in Patent Document 1, feathery crystals can still form in practice. The effect of refining the crystal grain size and suppressing the formation of abnormal structures, as well as the effect of reducing macroscopic segregation of solute elements and suppressing casting cracks, are not sufficient, and a stable and satisfactory quality of ingot could not be obtained.

[0011] The present invention was devised in view of the above points, and aims to provide a stirring bar and a method for manufacturing an aluminum alloy ingot that can reduce macroscopic segregation of solute elements, refine the crystal grain size to suppress the occurrence of abnormal structures, and suppress casting cracks. [Means for solving the problem]

[0012] To achieve the above objective, the present invention provides a stirring bar for stirring molten aluminum or an aluminum alloy, comprising a predetermined rotating shaft, rotating blades that rotate in conjunction with the rotation of the rotating shaft, a flow straightening plate located above the rotating blades, and a projection provided on the lower edge of the flow straightening plate.

[0013] Here, the agitator is equipped with a projection on the lower edge of the flow straightening plate, which allows the horizontal discharge flow generated by rotation to be directed downward (towards the solidification interface). This allows for sufficient perpendicular flow to the solidification interface, suppressing grain growth that causes grain coarsening and the growth of abnormal structures.

[0014] The rectifier plate may be integrated with the "rotating shaft and rotating blades" or be a separate component. However, if the "rotating shaft and rotating blades" and the "flow straightener" are separate components, the rotating shaft and flow straightener will come into contact and rub against each other, shortening the lifespan of both the rotating shaft and the flow straightener. Furthermore, there is a risk that slag generated by the rubbing may be mixed into the ingot. Therefore, from the perspective of preventing slag from being mixed into the ingot due to rubbing, it is preferable for the flow straightener to be formed integrally with the rotating shaft.

[0015] Furthermore, if the protrusion is located outside the rotating blade in a plan view, the horizontal discharge flow generated by the rotation can be directed even more effectively downward (towards the solidification interface).

[0016] Furthermore, if the rectifier plate is provided with multiple protrusions and the spacing between these protrusions is 8 mm or less, the horizontal flow velocity can be suppressed, allowing the rotation speed of the rotating shaft to be increased. By increasing the rotation speed, a more sufficient vertical flow can be obtained at the solidification interface.

[0017] Furthermore, in order to achieve the above objective, the present invention provides a method for manufacturing an aluminum alloy ingot, comprising a casting step of rotating a predetermined agitator having a predetermined rotating shaft and rotating blades that rotate in conjunction with the rotation of the rotating shaft, thereby solidifying the molten metal while oscillating the metal, wherein the casting step involves rotating the agitator with a flow straightening plate having a projection on its lower edge positioned between the surface of the molten metal and the rotating blades.

[0018] According to the present invention's method for manufacturing aluminum alloy ingots, the agitation of the molten metal promotes the formation of crystal grains, thereby suppressing grain growth that causes the crystal grain size to coarse and the growth of abnormal structures.

[0019] In other words, in this invention, a predetermined stirring bar is rotated in molten aluminum or an aluminum alloy, causing the molten metal to oscillate while solidifying. As a result, the oscillating molten metal causes the solidification interface to receive a predetermined pressure through the flow, thereby suppressing grain growth that causes grain size coarsening and the growth of abnormal structures, as described above.

[0020] In this casting process, a flow straightening plate with a projection on its lower edge is positioned between the molten metal surface and the rotating blades, and the agitator is rotated. This directs the horizontal discharge flow generated by the rotation downwards (towards the solidification interface). As a result, the oscillation of the molten metal becomes a flow that includes vectors perpendicular to the solidification interface, rather than a flow consisting only of vectors parallel to the solidification interface, such as a swirling flow.

[0021] When the velocity of this flow is decomposed into a "vector perpendicular to the solidification interface" and "vectors other than that", when the "vector perpendicular to the solidification interface" is greater than or equal to a predetermined value (for example, 0.1 m / sec or more), the problem of macro-segregation of solute elements caused by the stirring effect of the flow can also be solved together.

[0022] In addition, such fluctuations of the molten metal are effective in refining the crystal grain size, and the crystal grain size can be refined without adding a refining agent (for example, titanium, boron, etc.).

[0023] Thus, the present invention mechanically imparts fluctuations to the molten metal, reduces macro-segregation of solute elements, and by applying a pressure including a vector perpendicular to the solidification interface to the molten metal, the crystal grain size can be refined to suppress the generation of abnormal structures and suppress casting cracks.

[0024] In addition, since the present invention positions a predetermined flow rectifying plate between the molten metal surface and the rotating blades, it is possible to suppress the depression of the molten metal surface by suppressing the drawing-in of the molten metal from above the stirrer. Furthermore, the flow of the molten metal generated by the stirrer can be concentrated between the stirrer and the solidification interface, and the stirring efficiency near the solidification interface can be improved.

[0025] When a swirling flow is generated by the rotation of the stirrer, the flow is transmitted in the direction of the molten metal surface (upward) due to the friction of the molten metal, and the drawing-in of the molten metal surface by the vortex occurs. Then, when "depression of the molten metal surface" occurs due to the drawing-in of the molten metal surface, foreign substances such as oxides floating on the molten metal surface are mixed into the ingot, and the quality of the ingot deteriorates. That is, in order to prevent foreign substances from being mixed into the ingot, the rotation speed of the stirrer is naturally restricted.

[0026] However, when a flow rectifying plate is positioned between the molten metal surface and the rotating blades, it is possible to prevent the generation of a drawing-in flow of the molten metal from above the stirrer. In addition, since the transmission of the swirling flow generated by the rotation of the stirrer in the direction of the molten metal surface is inhibited, an effect of suppressing the generation of vortices near the molten metal surface can also be expected. That is, by suppressing the generation of "depressions on the soup surface" using the flow rectifying plate, the rotational speed of the agitator can be increased, and large fluctuations can be imparted to the molten metal.

[0027] From these facts, it can be considered that when the flow rectifying plate is positioned between the soup surface and the rotating blades, the influence of stirring above the agitator becomes smaller. That is, it is also possible to expect an effect of increasing the stirring efficiency by causing most of the energy used for stirring to act below the agitator (near the solidification interface).

[0028] In addition, in the method for producing an aluminum alloy ingot of the present invention, the purity of the aluminum alloy can also be 99.99 wt% or more.

[0029] In the case of a high-purity aluminum alloy with a purity of 99.99 wt% or more, although it is difficult to add a grain refinement material (for example, titanium or boron), in the present invention, without adding a grain refinement material, refinement of the crystal grain size is achieved, so that refinement of a high-purity aluminum alloy is possible.

Advantages of the Invention

[0030] In the agitator and the method for producing an aluminum alloy ingot of the present invention, the crystal grain size of the ingot can be refined to suppress the generation of abnormal structures, reduce the macro-segregation of solute elements, and suppress casting cracks.

Brief Description of the Drawings

[0031] [Figure 1] It is a schematic diagram for explaining a manufacturing apparatus used in an example of the method for producing an aluminum alloy ingot of the present invention. [Figure 2] It is a schematic diagram showing variations in the angle of the rotating blades of the agitator. [Figure 3] It is a schematic diagram showing the flow of molten metal when the agitator stirs the molten metal. [Figure 4] It is a schematic diagram showing variations in the flow rectifying plate. [Figure 5]This is a schematic diagram showing the flow of molten metal when a stirring bar is rotated at the bottom of the casting mold. [Figure 6] This is a schematic diagram showing the flow of molten metal when a stirrer without a baffle plate is rotated at the bottom of a casting mold. [Figure 7] This is a schematic diagram illustrating the rotating blades of the stirring bar in the example. [Figure 8] This is a schematic diagram illustrating the rectifier plate in the embodiment. [Figure 9] This is a schematic diagram showing variations in guide height in the embodiment. [Figure 10] This is a schematic diagram showing variations in guide width in the embodiment. [Figure 11] This is a schematic diagram showing variations in the opening of the rectifier plate in the embodiment. [Figure 12] This is a schematic diagram showing variations in the guide's cutout width in the embodiment. [Figure 13] This figure shows the state of the crystal grains on a cross-section of an aluminum alloy ingot. [Modes for carrying out the invention]

[0032] The following describes embodiments for carrying out the invention (hereinafter referred to as "embodiments"). Here, we will explain using the example of manufacturing an aluminum alloy ingot, which is the material for a sputtering target, using the HOTTOP casting method.

[0033] Figure 1 is a schematic diagram illustrating the structure of the ingot manufacturing apparatus M used in the method for manufacturing aluminum alloy ingots according to the present invention. The ingot manufacturing apparatus M shown in Figure 1 has a vertical mold 1 with a jacket structure, and a molten metal receiving container 2 made of heat-insulating refractory material and having a molten metal reservoir 20 with a diameter smaller than the diameter of the mold 1 is placed on top of the mold 1. Furthermore, the molten metal receiving container 2 is connected to a runner 21 for injecting molten aluminum alloy into the molten metal reservoir 20.

[0034] Furthermore, while a solidification interface S is formed on the upper surface of the ingot during casting, the aluminum alloy is sequentially injected into the molten metal reservoir 20 of the molten metal receiving container 2 through the runner 21, filling the reservoir 20 to a predetermined height of molten metal level 90.

[0035] Furthermore, a stirring bar 3 is positioned inside the hot water reservoir 20. The stirring bar 3 comprises a rotating shaft 30, a rotating blade 31c attached to the tip of the rotating shaft 30, and a flow straightening plate 32 attached above the rotating blade 31c. The rotating shaft 30, the rotating blade 31c, and the flow straightening plate 32 are made of carbon or ceramics.

[0036] In this embodiment, in order to agitate the molten metal near the solidification interface, it is necessary to insert the agitator 3 into the upper molten metal reservoir or mold and rotate the agitator. For this purpose, the rotating shaft 30 is provided to be rotatable in both forward and reverse directions by a motor (not shown), and the rotation period is set to 5 seconds.

[0037] Furthermore, the period of forward and reverse rotation does not necessarily have to be 5 seconds, as long as the entire solidification interface S is exposed.

[0038] Furthermore, as shown in Figure 2 (the rectifier plate 32 is not shown in Figures 2 and 3), the inclination angle of the rotating blades with respect to the rotation plane perpendicular to the rotation axis 30 is set appropriately, resulting in several variations.

[0039] For example, the rotating blades 31a (90° relative to the plane of rotation) shown in Figure 2(a), 31b (60° relative to the plane of rotation) shown in Figure 2(b), 31c (45° relative to the plane of rotation) shown in Figure 2(c), 31d (30° relative to the plane of rotation) shown in Figure 2(d), and 31e (0° relative to the plane of rotation) shown in Figure 2(e) can be used. Although there are differences in stirring efficiency, in practical terms, stirring is possible with settings ranging from 70° to 20°.

[0040] Furthermore, when tests were conducted with the rotating blades 31a to 31e shown in Figure 2, the rotating blade 31c, which is inclined at 45° with respect to the rotation plane perpendicular to the rotation axis 30, was found to have the best balance between the area receiving the molten metal and the proportion of the molten metal being discharged downwards and flowing during forward rotation, making it the most efficient rotating blade.

[0041] In contrast, with the rotating blade 31b tilted at 60° (see Figure 3(a)), although the area receiving the molten metal (area indicated by symbol 3A) is large, the proportion of molten metal discharged horizontally (indicated by symbol 3B) is large, resulting in a smaller proportion of molten metal discharged downwards and allowed to flow (indicated by symbol 3C). In Figure 3(a), the symbol R indicates the direction of rotation of the rotation axis 30.

[0042] Furthermore, with the rotating blade 31d tilted at 30° (see Figure 3(b)), the proportion of molten metal discharged horizontally, indicated by symbol 3E, is small. As a result, although the proportion of molten metal discharged downwards and allowed to flow, indicated by symbol 3F, is large, the area received by the molten metal (area indicated by symbol 3D) becomes small. In Figure 3(b), the symbol R indicates the direction of rotation of the rotation axis 30.

[0043] Furthermore, it was confirmed that, at the same rotational speed, the 45° rotating blade 31c produced the greatest "downward flow velocity of molten metal." Furthermore, it was confirmed that even with the influence of differences in the angle of the rotating blades, sufficient vertical flow to the solidification interface can be obtained by adjusting the stirring speed, even at inclination angles of 70° to 20°.

[0044] Furthermore, with the rotating blade 31a tilted at 90° (see Figure 2(a)), a normal structure was obtained only directly beneath the stirring bar 3, and feathery crystals were formed around it. This is thought to be because an inductive flow (vertical flow) was generated only directly beneath the stirring bar 3 and exerted an effect. Furthermore, this suggests that the casting structure is improved not only by the pressure generated by the flow toward the solidification interface S, but also by the pressure generated by the flow away from the solidification interface (negative pressure).

[0045] Furthermore, in the case of the rotating blade 31a tilted at 90°, it was confirmed that tissue abnormalities occurred despite the presence of flow parallel to the solidification interface S. Therefore, it was determined that the effect of flow parallel to the solidification interface S is nonexistent or almost nonexistent.

[0046] Furthermore, with the rotating blade 31e tilted at 0° (see Figure 2(e)), the area receiving the molten metal was extremely small, making it difficult to generate vertical flow.

[0047] Here, the shape of the rotating blades is not limited to curved plates with the same angle (45°) to each other as in this embodiment, but may also be curved plates with different angles to each other, and the shape of the rotating blades is not particularly limited, and may be a plate, a circular or elliptical straight plate, etc.

[0048] Furthermore, a flow straightening plate 32 is provided between the rotating blade 31c of the agitator 3 of the ingot manufacturing apparatus M and the molten metal surface 90 to block or obstruct the flow of the molten metal. The rectifier plate 32 is fixedly positioned, for example, on top of the rotating blades 31c (see Figures 4A to D). Alternatively, the rectifier plate 32 may be separated from the rotating shaft 30 or the rotating blades 31c and fixed externally (see Figure 4E).

[0049] In the variation shown in Figure 4, all of the rectifier plates 32 have a disc shape when viewed from above or below.

[0050] Here, when a swirling flow is generated by the rotation of the agitator 3, the flow is transmitted upwards (towards the molten metal surface) due to friction in the molten metal, causing the molten metal surface to be pulled in by a vortex. When a flow straightening plate 32 is attached to the agitator 3 (as in Figure 5), the generation of a pull-in flow from above the agitator 3 can be prevented. In addition, since the transmission of the swirling flow towards the molten metal surface due to the rotation of the agitator 3 is inhibited, a vortex generation suppression effect can also be expected.

[0051] From these observations, it is considered that the rectifier plate 32 can reduce the influence of stirring on the area above the agitator 3 (the region indicated by the symbol 5A in Figure 5). In other words, it can be expected that the majority of the energy used for stirring will be directed below the agitator 3 (the region indicated by the symbol 5B in Figure 5, near the solidification interface S) (see Figure 5). Note that the symbol 5C in Figure 5 represents the "pull-in flow from below".

[0052] On the other hand, in the absence of the rectifier plate 32 (as shown in Figure 6), the effect of stirring extends to the entire molten metal (in other words, the stirring effect on the solidification interface S is not effectively achieved). Note that in Figure 6, symbol 6A represents the "intake flow from above," but the agitator 3 discharges the molten metal downwards to create a flow, and the same amount of molten metal is then drawn in from above.

[0053] The rectifier plate 32 may be not only rectifier plate A in Figure 4, but also rectifier plates B through E. In A, a guide (an example of a projection) 33 is provided on the lower peripheral edge to direct the horizontal discharge flow toward the solidification interface S, and the inner surface of the guide 33 is formed in a straight line. In B, a guide 33 is provided on the lower peripheral edge to direct the horizontal discharge flow toward the solidification interface S, and the inner surface of the guide 33 in B is formed in a curved shape.

[0054] C and D are positioned at a distance from the rotating blade 31c (the same guide 33 as the straightener plate A is provided for the straightener plate C, and it is positioned vertically above the straightener plate A. The same guide 33 as the straightener plate B is provided for the straightener plate D, and it is positioned vertically above the straightener plate B).

[0055] E is fixed externally, independently of the rotating shaft 30 or the rotating blades 31c. Alternatively, it may be fixed and positioned on the inner surface (not shown) of the molten metal receiving container 2 that faces the molten metal reservoir 20.

[0056] By the way, depending on the structure of the ingot manufacturing apparatus M and the position of the agitator 3, increasing the rotation speed of the agitator 3 may increase the horizontal discharge flow rate, which could cause problems.

[0057] For example, in the hottop casting method, a method of pressurizing the molten metal with gas (gas-pressurized hottop casting) is sometimes applied to improve the appearance of the ingot. Furthermore, when using a flow straightening plate without a guide, if the position of the flow straightening plate (position in the Z-axis direction) coincides with the gas-pressurized section (the gas pressurizing the molten metal), the increase in rotational speed is restricted in order to avoid damage to the gas-pressurized section due to an increase in the horizontal discharge flow rate.

[0058] In such cases (where the increase in rotational speed is limited by using a rectifier plate without a guide), with rectifier plates A to D, even if the rotational speed increases, the horizontal discharge flow rate does not increase, so the rotational speed can be increased. Furthermore, the rectifier plate (externally fixed type) of E can increase its rotational speed because its Z-axis direction is offset from the gas pressurized part of the part submerged in the hot water.

[0059] (Examples) The following describes the examples. In the embodiment, the stirring bar 3 used had a rotating blade 31c with a height of 20 mm in a front view (see Figure 7(a)), a length of approximately 25.3 mm in the direction of the 45° inclination angle in a side view (see Figure 7(b)), a thickness of 3 mm, a length of 20 mm in the short direction and 40 mm in the long direction in a bottom view (see Figure 7(c)), and a diameter of 15 mm on the rotating shaft (see Figure 7(c)).

[0060] Furthermore, in the embodiments (except for Embodiment 4), the rectifier plate 32 used had a diameter (outer diameter) of 57 mm and a diameter of 45 mm to the guide starting point (see Figure 8(a)). On the other hand, in Embodiment 4, a rectifier plate 32 having the outer diameter described later was used. For the purposes of this explanation, we will define the height of the guide indicated by the symbol A in Figure 8(b) as "guide height" and the width of the guide indicated by the symbol B in Figure 8(b) as "guide width".

[0061] Furthermore, in the examples (except for Example 3), an integrated rectifier plate 32 was used. On the other hand, in Example 3, a separate type rectifier plate 32, as described later, was also used. Furthermore, in the examples (except for Example 5), a guide 33 without a notched portion was used. On the other hand, in Example 5, a guide 33 with a notched portion as described below was also used.

[0062] In addition, in the examples, the rotation speed of the stirring bar 3 was 450 rpm (250 rpm in Example 6 only), the rotation direction was forward and reverse rotation, with a cycle of 5 seconds of forward rotation, 1 second of rest, 5 seconds of reverse rotation, and 1 second of rest, and the installation height of the stirring bar 3 was 122 mm from the top surface of the molten metal receiving container 2 to the top of the rotating blades 3c of the stirring bar 3.

[0063] Furthermore, in the water test, the stirring bar 3 was rotated in 10°C water containing beads (which could be evaluated as having a viscosity equivalent to molten aluminum at 700°C), and the maximum value of the velocity component in the horizontal direction (perpendicular to the rotation axis 30) was confirmed by calculating the distance the beads moved per unit time. In addition, in Examples 1 to 4, the maximum value of the velocity component in the direction perpendicular to the solidification interface S was also confirmed.

[0064] ■Example 1 (See Figure 9) In Example 1, water tests were conducted for six patterns: when no guide was provided, and when the "guide height" was 2.5 mm (see Figure 9(a)), 5.0 mm (see Figure 9(b)), 7.5 mm (see Figure 9(c)), 10 mm (see Figure 9(d)), and 15 mm (see Figure 9(e)). (The "diameter to the starting point of the guide" was fixed at 45 mm, and the "guide width" was fixed at 5 mm.)

[0065] The angles formed by the lower surface (horizontal plane) of the rectifier plate 32 and the inner surface (inclined surface) of the guide 33 are 153.4° in Figure 9(a), 135° in Figure 9(b), 123.6° in Figure 9(c), 116.5° in Figure 9(d), and 108.4° in Figure 9(e).

[0066] Table 1 shows the "horizontal flow velocity (maximum value)" and the "vertical flow velocity (maximum value)".

[0067] [Table 1] TIFF2026113960000002.tif42169

[0068] Table 1 shows that, compared to the case without guide 33, the horizontal flow velocity (maximum value) is lower in all cases when guide 33 is provided (when the guide height is 2.5 mm to 15 mm).

[0069] Furthermore, Table 1 shows that, compared to the case where guide 33 is not provided, the vertical flow velocity is greater when the guide height is "2.5 mm", "5 mm", and "7.5 mm".

[0070] Furthermore, when the guide height is "10mm" or "15mm," although the vertical flow velocity is reduced, the horizontal flow velocity is sufficiently reduced, allowing the rotation speed to be increased. By increasing the rotation speed, the vertical flow velocity can be increased.

[0071] ■Example 2 (See Figure 10) In Example 2, water tests were conducted for six patterns: when no guide was provided, and when the "guide width" was 5 mm (see Figure 10(a)), 4 mm (see Figure 10(b)), 3 mm (see Figure 10(c)), 2 mm (see Figure 10(d)), and 1 mm (see Figure 10(e)) (the "guide height" was fixed at 5 mm).

[0072] The angles formed by the lower surface (horizontal plane) of the rectifier plate 32 and the inner surface (inclined surface) of the guide 33 are 135° in Figure 10(a), 128.6° in Figure 10(b), 120.9° in Figure 10(c), 111.8° in Figure 10(d), and 101.3° in Figure 10(e).

[0073] Furthermore, the "diameter to the guide starting point" is 45 mm for Figure 10(a), 47 mm for Figure 10(b), 49 mm for Figure 10(c), 51 mm for Figure 10(d), and 53 mm for Figure 10(e).

[0074] Table 2 shows the "horizontal flow velocity (maximum value)" and the "vertical flow velocity (maximum value)".

[0075] [Table 2] TIFF2026113960000003.tif42170

[0076] Table 2 shows that, compared to the case without guide 33, the horizontal flow velocity (maximum value) is lower in all cases when guides are provided (when the guide width is 1 mm to 5 mm).

[0077] Furthermore, Table 2 shows that, compared to the case where guide 33 is not provided, the vertical flow velocity (maximum value) is higher in all cases when guide 33 is provided (when the guide width is 1 mm to 5 mm).

[0078] ■Example 3 (See Figure 11) In Example 3, water tests were conducted for the following cases: when no guide is provided, when an integrated rectifier plate 32 (type A in Figure 4, see Figure 11(a)), and when a separate rectifier plate 32 supported by a support rod 11 (type E in Figure 4, see Figure 11(b)). (The "diameter to the guide starting point" of the integrated rectifier plate 32 and the separate rectifier plate 32 were fixed at 45 mm, the "guide width" at 5 mm, and the "guide height" at 5 mm.)

[0079] Furthermore, water tests were conducted on the separate type rectifier plate 32 for three patterns with an "inner diameter of the opening" of 20 mm (see Figure 11(c)), 30 mm (see Figure 11(d)), and 40 mm (see Figure 11(e)).

[0080] The clearance with the rotating shaft 30 (the diameter of the rotating shaft is 15 mm) (indicated by the symbol W in Figure 11(b)) is 2.5 mm in Figure 11(c), 7.5 mm in Figure 11(d), and 12.5 mm in Figure 11(e).

[0081] Table 3 (Tables 3-1 to 3-3) shows the "horizontal flow velocity (maximum value)" and the "vertical flow velocity (maximum value)".

[0082] [Table 3-1]: When no guide is provided TIFF2026113960000004.tif18170

[0083] [Table 3-2]: In the case of an integrated rectifier plate TIFF2026113960000005.tif18170

[0084] [Table 3-3]: In the case of a separate type rectifier plate TIFF2026113960000006.tif27170

[0085] Table 3 shows that, compared to the case where guide 33 is not provided, the horizontal flow velocity (maximum value) is reduced in both cases where guide 33 is provided (in the case of an integrated rectifier plate and in the case of a separate rectifier plate).

[0086] Furthermore, Table 3 shows that, compared to the case where the guide section 33 is not provided, the case where the guide 33 is provided (both the case of an integrated rectifier plate and the case of separate rectifier plates with an inner diameter of 20 mm and 30 mm at the opening) shows that the vertical flow velocity (maximum value) is increased in both cases.

[0087] Furthermore, with separate-type rectifier plates, when the inner diameter of the opening becomes 40 mm, there is a tendency for the maximum value of the "vertical flow velocity" to decrease (the tendency for this to worsen is observed when the inner diameter of the opening of the rectifier plate 32 becomes 40 mm).

[0088] ■Example 4 In Example 4, water tests were conducted for 16 patterns: when the outer diameter of the rectifier plate 32 was "57 mm", "70 mm", "80 mm", and "100 mm", with no guide provided, and with guide heights of 5 mm, 7.5 mm, and 10 mm (the guide width was fixed at 5 mm).

[0089] The "diameter to the guide starting point" is 45 mm when the outer diameter of the rectifier plate 32 is 57 mm, 58 mm when the outer diameter of the rectifier plate 32 is 70 mm, 68 mm when the outer diameter of the rectifier plate 32 is 80 mm, and 88 mm when the outer diameter of the rectifier plate 32 is 100 mm.

[0090] Table 4 shows the "horizontal flow velocity (maximum value)" and the "vertical flow velocity (maximum value)".

[0091] [Table 4] TIFF2026113960000007.tif91169

[0092] Table 4 shows that, compared to the case where guide 33 is not provided, the horizontal flow velocity (maximum value) is lower in all cases when guide 33 is provided (when the outer diameter of the flow straightener plate is 57 mm to 100 mm).

[0093] Furthermore, Table 4 shows that, compared to the case without guide 33, the case with guide 33 (when the outer diameter of the rectifier plate is 57 mm to 100 mm) always shows an increase in the vertical flow velocity (maximum value).

[0094] Furthermore, as the outer diameter of the rectifier plate 32 increases, the effect of the guide 33 in suppressing the "horizontal flow velocity" decreases. When the outer diameter of the rectifier plate 32 is between 57 mm and 70 mm, there is almost no change in the maximum value of the "horizontal flow velocity." However, when the outer diameter of the rectifier plate 32 exceeds 80 mm, there is a tendency for the maximum value of the "horizontal flow velocity" to increase (and this tendency worsens when the outer diameter of the rectifier plate 32 exceeds 80 mm).

[0095] Furthermore, the larger the outer diameter of the rectifier plate 32, the greater the improvement in "vertical flow velocity" due to the guide 33, but the rate of increase in "vertical flow velocity" plateaus when the outer diameter of the rectifier plate 32 reaches 70 mm.

[0096] ■Example 5 (See Figure 12) In Example 5, water tests were conducted for the following cases: without guide 33, without a notched portion of guide 33 (gap between guides 33), and with a notched portion of guide 33 (the "diameter to the starting point of the guide" was fixed at 45 mm, the "guide width" at 5 mm, and the "guide height" at 5 mm).

[0097] Furthermore, for the case where "a notched section is provided in the guide," water tests were conducted for five patterns in which the guide was divided into 4 sections (see Figure 12(a)), 8 sections (see Figure 12(b)), 16 sections (see Figure 12(c)), 32 sections (see Figure 12(d)), and 64 sections (see Figure 12(e)), with the circumference length set at 100% and the total of the notched sections being 20%.

[0098] The notches in the guide are evenly spaced, and the width of the notches is 7.04 mm in Figure 12(a), 3.53 mm in Figure 12(b), 1.77 mm in Figure 12(c), 0.88 mm in Figure 12(d), and 0.44 mm in Figure 12(e).

[0099] Table 5-1 shows the "horizontal flow velocity (maximum value)". Table 5-2 also shows the relationship between "gap width" and "horizontal flow velocity (maximum value)".

[0100] [Table 5-1] TIFF2026113960000008.tif43170

[0101] [Table 5-2] JPEG2026113960000009.jpg56170

[0102] Table 5-1 shows that, compared to the case without guide 33, the horizontal flow velocity (maximum value) is smaller in all cases when guide 33 is provided (when the chipping width is 0 to 7.04).

[0103] Furthermore, from the approximate straight line in Table 5-2, it can be seen that the performance is comparable to that without a guide (when the maximum horizontal flow velocity is 109 mm / sec) when the gap width is 8.04 mm. Therefore, when the gap width is smaller than 8.04 mm (for example, 8 mm or less), it can be seen that the guide 33 has the effect of suppressing the maximum horizontal flow velocity.

[0104] ■Example 6 (See Figure 13) In Example 6, aluminum alloy ingots were manufactured in two patterns: one with no guide and one with a guide (the "diameter to the starting point of the guide" was 45 mm, the "guide height" was 5 mm, and the "guide width" was 5 mm).

[0105] Here, using the radius of the aluminum alloy ingot as a reference, feathery crystals are generated in the region corresponding to approximately 70-95% from the center (the region indicated by the symbol A in Figure 13(a)) when the grain refinement is insufficient, so it is necessary to focus on this region. Furthermore, the region corresponding to approximately 95-100% of the center (indicated by the symbol B in Figure 13(a), and called the "primary (initial) solidification layer") is a structure formed by rapid cooling due to contact with the mold, and is not directly related to grain refinement.

[0106] Figure 13(b) shows the cross-sectional structure of an aluminum alloy ingot "without a guide," and Figure 13(c) shows the cross-sectional structure of an aluminum alloy ingot "with a guide."

[0107] As shown in Figure 13(b), when no guide is provided (i.e., when the velocity component perpendicular to the solidification interface S is small), a region where feathery crystals 5 are generated around the central part where the crystal grains are relatively fine was observed.

[0108] On the other hand, as shown in Figure 13(c), when a guide is provided (i.e., when the velocity component perpendicular to the solidification interface S is large), the crystal grains are fine across almost the entire surface, there are no abnormal structures, and no feathery crystals are formed. Furthermore, macroscopic segregation of solute elements is reduced, and there are no casting cracks. [Explanation of symbols]

[0109] M Ingot manufacturing equipment 1. Mold 11 Support rod 2. Molten metal receiver 20 Hot spring pool 21 Yudo 3. Stirring bar 30 Rotation axis 31a, 31b, 31c, 31d, 31e Rotating blades 32 Rectifier plate 5. Feathered crystals 9. Molten metal 90 Water level S solidification interface

Claims

1. A stirring bar for stirring molten aluminum or aluminum alloy, A predetermined axis of rotation, A rotating blade that rotates in conjunction with the rotation of the rotating shaft, A rectifier plate located above the rotating blade, The rectifier plate comprises a projection provided on the lower edge of the rectifier plate. Stirring bar.

2. The rectifier plate is formed integrally with the rotating shaft. The stirring bar according to claim 1.

3. In a plan view, the aforementioned projection is located outside the rotating blade. The stirring bar according to claim 1.

4. The rectifier plate is provided with a plurality of the aforementioned protrusions, and the distance between the aforementioned protrusions is 8 mm or less. The stirring bar according to claim 1.

5. A method for manufacturing an aluminum alloy ingot, comprising a casting step of rotating a predetermined agitator having a predetermined rotating shaft and rotating blades that rotate in conjunction with the rotation of the rotating shaft, in which the molten aluminum or aluminum alloy is solidified while being agitated, The aforementioned casting process is The agitator is rotated with a flow straightening plate, which has a projection on its lower edge, positioned between the surface of the molten metal and the rotating blade. A method for manufacturing aluminum alloy ingots.

6. The aforementioned projection directs the horizontal discharge flow toward the solidification interface. The method for manufacturing an aluminum alloy ingot according to claim 5.

7. The stirring bar is rotated together with the rectifier plate. The method for manufacturing an aluminum alloy ingot according to claim 5.

8. The rectifier plate is supported independently of the agitator, The stirring bar is rotated without being linked to the rectifier plate. The method for manufacturing an aluminum alloy ingot according to claim 5.

9. The aluminum alloy has a purity of 99.99 wt% or higher. The method for manufacturing an aluminum alloy ingot according to claim 5.

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