JP6858184B2 - Stirrer blade and stirrer - Google Patents

Description

The present disclosure relates to a stirrer blade and a stirrer.

Conventionally, a stirring device for mixing a plurality of substances with each other is known. For example, Patent Document 1 below discloses an example of a stirring device using a stirring blade. This conventional stirring blade is attached to the tip of a shaft that is driven to rotate, and the mixture to be stirred (“target material”) is housed in a predetermined container. By rotating the stirring blade in this container, the target material is stirred.

Generally, in a conventional stirring device, the target material is sufficiently stirred in the vicinity of the stirring means (such as the stirring blade described above), and different substances are well mixed (high dispersion degree). On the other hand, when the material is separated from the stirring means, the target material is not sufficiently stirred and the degree of dispersion is low. As described above, in the conventional stirring device, the degree of dispersion differs depending on the place, and the target material as a whole tends to be qualitatively non-uniform (that is, the degree of mixing is low).

Japanese Unexamined Patent Publication No. 10-180073

This disclosure was conceived under the circumstances described above. Therefore, one object of the present disclosure is to provide a stirring blade and a stirring device capable of improving both the dispersion degree and the mixing degree of the target material as compared with the conventional case.

According to the first aspect of the present disclosure, a stirring blade that rotates about an axis is provided. The stirring blade is a stirring blade that rotates around an axial center, and is provided on a base portion attached to a rotating shaft defining the axial center and a first side of the base portion in a direction parallel to the axial center. A plurality of first blade portions arranged around the axis are provided, and the plurality of first blade portions have inner and outer ends and tips in the radial direction perpendicular to the axis, respectively. The stirring blade further includes a plurality of second blade portions, and the base portion has a blade surface having an outer edge and a front curved portion connected to the inner end thereof and convex forward in the rotation direction. It has a second side opposite to the first side with respect to a direction parallel to the axis, and the plurality of second blades are provided on the second side and around the axis. The plurality of second blade portions are arranged so as to be connected to the inner end and the outer end in the radial direction perpendicular to the axis, and the blade surface having the tip as the outer edge, and the inner end thereof. It has a front curved portion that is convex forward in the rotation direction, and the first side and the second side of the base portion are tapered cones in directions opposite to each other in a direction parallel to the axis. The base portion has a first inclined surface formed by the side surface of the conical base on the first side and a second inclined surface formed by the side surface of the conical base on the second side, and the plurality of first portions. The one blade portion is provided on the first inclined surface, and the plurality of second blade portions are provided on the second inclined surface.

Preferably, each of the first blade portions has a rear curved portion that is connected to the front curved portion outward in the radial direction and is convex rearward in the rotational direction.

Preferably, each of the first blade portions is tilted so as to be positioned forward in the rotational direction so as to be separated from the base portion in a direction parallel to the axial center.

Preferably, the inclination angle of each of the first blades with respect to the direction parallel to the axis is larger toward the inward in the radial direction.

Preferably, the position of the plurality of first blades in the rotation direction is different from that of the plurality of second blades.

The stirring device provided by the second side surface of the present disclosure includes a stirring blade provided by the first side surface, a container accommodating a stirring target, and a rotating shaft inserted into the container and to which the stirring blade is attached. To be equipped.

Other features and advantages of the present disclosure will become more apparent with the detailed description given below with reference to the accompanying drawings.

It is a perspective view which shows the stirring blade based on 1st Embodiment of this disclosure. It is a front view which shows the stirring blade based on 1st Embodiment of this disclosure. It is a top view which shows the stirring blade based on 1st Embodiment of this disclosure. It is sectional drawing which shows the stirring apparatus using the stirring blade based on 1st Embodiment of this disclosure. It is a perspective view which shows the stirring blade based on 2nd Embodiment of this disclosure. It is a top view which shows the stirring blade based on 2nd Embodiment of this disclosure. It is a figure which shows the stirring state by the stirring blade of 1st Embodiment. It is a figure which shows the stirring state by the stirring blade of 2nd Embodiment. It is a perspective view which shows the stirring blade of a comparative example. It is a figure which shows the stirring state by the stirring blade of the comparative example. It is a perspective view which shows the stirring blade based on 3rd Embodiment of this disclosure. It is a front view which shows the stirring blade based on 3rd Embodiment of this disclosure. It is sectional drawing which shows an example of the stirring apparatus using the stirring blade based on the 3rd Embodiment of this disclosure. It is a perspective view which shows the stirring blade based on 4th Embodiment of this disclosure. It is a perspective view which shows the stirring blade based on 5th Embodiment of this disclosure. It is a figure which shows the stirring state by the stirring blade of 3rd Embodiment. It is a figure which shows the stirring state by the stirring blade of 4th Embodiment. It is a figure which shows the stirring state by the stirring blade of 5th Embodiment. It is a figure which shows the stirring state by the stirring blade of the comparative example. It is a figure which shows the flow trace analysis result of the marker which was agitated by the stirring vane of 3rd Embodiment. It is a figure which shows the flow trace analysis result of the marker which was agitated by the stirring vane of 4th Embodiment. It is a figure which shows the flow trace analysis result of the marker which was agitated by the stirring vane of 5th Embodiment. It is a figure which shows the flow trace analysis result of the marker which was agitated by the stirring blade of the comparative example. It is sectional drawing which shows the other example of the stirring apparatus using the stirring blade of 3rd Embodiment.

Hereinafter, preferred embodiments of the present disclosure will be specifically described with reference to the drawings.

In the present disclosure, "stirring" may imply "dispersion" and "mixing" without particular limitation. Dispersion means that another substance (for example, powder or another kind of liquid) is microscopically scattered in a substance (for example, a liquid) which is chemically in one phase. In addition, mixing means making the degree of dispersion uniform over the entire target material. For example, suppose the target material consists of liquid A and powder B. In this case, "stirring" of the target material means that (at least a part of) the powder B is scattered in (at least a part of) the liquid A ("dispersion"), and that the scattered state of the powder B is the target material. It can mean creating a predetermined flow (“mixing”) in the target material so that it is the same (or substantially the same) anywhere in the material.

1 to 3 show stirring blades based on the first embodiment of the present disclosure. The illustrated stirring blade A1 includes a base 1 and a blade group 2.

FIG. 1 is a perspective view showing the stirring blade A1. FIG. 2 is a front view showing the stirring blade A1. FIG. 3 is a plan view showing the stirring blade A1. In FIGS. 1 and 3, the direction in which the stirring blade A1 rotates (circumferential direction) is indicated by θ. In FIG. 2, the direction in which the stirring blade A1 rotates is indicated by an arrow attached below the stirring blade A1. Further, in these figures, the direction parallel to the rotation axis (axial direction) of the stirring blade A1 is indicated by z, and the direction perpendicular to the axial direction z (diameter direction) is indicated by r.

The stirring blade A1 is attached to, for example, the stirring device B1 shown in FIG. The stirring device B1 includes a container 81, a rotating shaft 82, a driving unit 83, and a shaft seal 85. The container 81 contains the target material T to be agitated. The rotating shaft 82 extends vertically through the bottom of the container 81, and a stirring blade A1 is attached to the upper end thereof. The shaft seal 85 is provided between the bottom of the container 81 and the rotating shaft 82, and allows the rotating shaft 82 to rotate, while preventing the target material T from leaking from the container 81 to the outside. The drive unit 83 includes, for example, an electric motor for rotating the rotation shaft 82 around a predetermined axis parallel to the axial direction z. As another component of the stirring device B1, without particular limitation, a housing for supporting the container 81 and the driving unit 83, a control unit for controlling the driving of the driving unit 83, and the like may be appropriately provided.

The stirring blade A1 is not particularly limited, and is formed of a material suitable for stirring the target material T, such as metal or resin. Examples of the metal forming the stirring blade A1 include stainless steel. The stirring blade A1 may be one in which the base portion 1 and the blade group 2 are integrally formed, or may be formed by combining a plurality of individually formed parts. As a means for attaching the stirring blade A1 to the rotating shaft 82, a well-known engaging mechanism, fastening mechanism, or the like can be adopted. Further, a part of the stirring blade A1 may be fixed (for example, adhered) to the rotating shaft 82 in advance, and the remaining part of the stirring blade A1 may be detachably attached to the part. The size of the stirring blade A1 is not particularly limited, and is appropriately selected according to the size of the container 81, the viscosity of the target material T, and the like. In one example, the diameter of the stirring blade A1 is about 40 mm.

The base 1 supports the blade group 2 and is fixed to the rotating shaft 82. The shape and size of the base 1 are not particularly limited. The illustrated base 1 has a circular shape in a plan view (axial z view). The base 1 has an outer peripheral end 10 and an inclined surface 11. In the present embodiment, the outer peripheral end 10 is located at the lower end of the base 1, and is circular in a plan view. The inclined surface 11 is provided above the outer peripheral end 10. The inclined surface 11 has a configuration in which the size in the radial direction r decreases toward the upper side in the axial direction z. In other words, the inclined surface 11 is tapered upward. In the illustrated example, the base 1 is a truncated cone (truncated cone) as a whole, and the inclined surface 11 is composed of the side surfaces of the truncated cone.

The blade group 2 is composed of a plurality of blade portions 20. These blade portions 20 are provided on the same surface side of the base portion 1 and are arranged apart from each other in the rotation direction θ. In the present embodiment, the plurality of blade portions 20 are provided on the inclined surface 11. As shown in FIG. 2, the plurality of blade portions 20 are arranged within a predetermined range in the axial direction z.

The number of blades constituting the blade group 2 is not particularly limited. In the present embodiment, the blade group 2 is composed of four blade portions 40. These four blades 20 are arranged at equal pitches in a plan view, and are separated from each other by 90 degrees in the rotation direction θ.

Each blade portion 20 has an inner end 21, an outer end 22, a base end 23, a tip 24, a front surface 25, a rear surface 26, a front curved portion 27, and a rear curved portion 28. The inner end 21 is a linear or curved edge having a predetermined length, which is located most inward in the radial direction r of the blade portion 20. In the present embodiment, the inner ends 21 of the plurality of blade portions 20 are separated from each other in the rotation direction θ. The outer end 22 is located on the outermost side of the blade portion 20 in the radial direction r, and is a linear or curved edge having a predetermined length. As shown in FIG. 3, the outer end 22 coincides with the outer peripheral end 10 of the base 1 in a plan view. That is, one of the base portion 1 and the blade portion 20 does not have a configuration in which one of the base portion 1 and the blade portion 20 protrude outward in the radial direction from the other. In another example, at least one blade portion 20 may be configured to protrude outward in the radial direction r from the base portion 1, or may be retracted inward in the radial direction r from the base portion 1. Good.

The base end 23 is a portion where the blade portion 20 is connected to the base portion 1. The tip 24 is a linear or curved edge having a predetermined length, separated from the base end 23 in the axial direction z.

The front surface 25 of each blade portion 20 is a front surface in the rotation direction θ, and the rear surface 26 is a rear surface.

The front curved portion 27 is a portion that is connected to the inner end 21 and is convex forward in the rotation direction θ in a plan view. More specifically, the front bending portion 27 has a shape that is convex forward in the rotation direction θ with respect to the virtual straight line connecting both ends of the front bending portion 27 in the radial direction r. The rear curved portion 28 is a portion that is connected to the front curved portion 27 in the radial direction r outward and is convex rearward in the rotational direction θ in a plan view. More specifically, the rear curved portion 28 has a shape that is convex rearward in the rotational direction θ with respect to the imaginary straight line connecting both ends in the radial direction r of the rear curved portion 28. In FIGS. 1 and 3, the range of the front bending portion 27 and the rear bending portion 28 is indicated by a alternate long and short dash line with an arrow. In the illustrated example, the tip 24 is provided in a portion of the blade portion 20 that generally constitutes the forward curved portion 27, and as shown in FIG. 3, has a shape that is convex forward in the rotation direction θ in a plan view. It has become. Further, the base end 23 is provided on both the front curved portion 27 and the portion constituting the rear curved portion 28, and as shown in FIG. 3, has an S-shape in a plan view. The range in which the front curved portion 27 and the rear curved portion 28 are provided, the degree of curvature of each, and the like are not particularly limited.

Further, in the present embodiment, each blade portion 20 is tilted so as to be positioned forward in the rotation direction θ so as to be separated from the base portion 1 in the axial direction z. Further, in the present embodiment, the inclination angle of the blade portion 20 with respect to the axial direction z becomes larger toward the inner side of the radial direction r. More specifically, as shown in FIG. 2, the angle α1 formed by the inner end 21 of the blade portion 20 with the axial direction z is larger than the angle α2 formed by the outer end 22 of the blade portion 20 with the axial direction z. Is. Therefore, the angle formed by the front bending portion 27 in the axial direction z is larger than the angle formed by the rear bending portion 28 in the axial direction z.

5 and 6 show stirring blades according to the second embodiment of the present disclosure. The structure of the blade portion 20 of the illustrated stirring blade A2 is different from that of the stirring blade A1 described above. FIG. 5 is a perspective view showing the stirring blade A2. FIG. 6 is a plan view of the stirring blade A2.

In the present embodiment, each blade portion 20 has only one curved portion, that is, a front curved portion 27, and does not have a rear curved portion 28. As shown in FIG. 6, in a plan view, the entire blade portion 20 is composed of the front curved portion 27. The relative relationship between the plurality of blades 20 in the stirring blade A2 and the configuration of the base 1 are substantially the same as those of the stirring blade A1. The stirring blade A2 is used by being attached to the stirring device B1 (FIG. 4) in the same manner as the stirring blade A1.

Next, the operations of the stirring blades A1 and A2 and the stirring device B1 will be described.

7 and 8 show an analysis example using the numerical fluid dynamics simulation of stirring by the stirring blades A1 and A2. In these figures, a plurality of arrows are attached to each of the plurality of points. Each arrow indicates the direction of flow of the target material at that point (however, the rotational direction θ component is not taken into consideration). In addition, the shades in the figure correspond to the flow velocity of the target material and indicate the flow velocity distribution of the target material (however, the rotational direction θ component is not taken into consideration). The lighter the color, the higher the flow velocity (the maximum flow velocity in the white region), and the darker the color, the lower the flow velocity (the lowest flow velocity in the black region). The flow velocity ratio between adjacent regions is 2.15. The conditions of this analysis are as follows. The inner diameter of the container 81 is 126 mm. The target material T is a high-viscosity non-Newtonian fluid (sodium carboxymethyl cellulose 1.7 wt%), and the liquid depth is 89.8 mm. A stirring blade A1 (FIG. 7) or A2 (FIG. 8) is arranged at the center of the bottom of the container 81. The rotation speed (peripheral speed) of the stirring blades A1 and A2 is 10 m / s.

When the stirring blades A1 and A2 rotate, a rotational flow along the rotation direction θ is generated in the target material T. Further, as can be understood from the arrows in FIGS. 7 and 8, the target material T is moved from above the stirring blades A1 and A2 (and near the liquid level) to the stirring blades A1 and A2 along the axial direction z. After flowing downward, it flows outward in the radial direction from the lower ends of the stirring blades A1 and A2 (near the outer peripheral end 10) along the bottom of the container 81. Further, the target material T flows upward along the side wall of the container 81, that is, toward the liquid surface. As a result of such flow, a large vortex is formed in the container 81. In FIGS. 7 and 8, the existence of two vortices symmetrical with respect to the rotation axes of the stirring blades A1 and A2 is confirmed. The generation of such a vortexed flow mainly contributes to the mixing of the target material T. Further, the flow velocity is maximum (see the white region) in the vicinity of the stirring blades A1 and A2, particularly in the vicinity of the outer peripheral end 10. Such a locally significant increase in the flow velocity mainly contributes to the dispersion of the target material T. As described above, according to the stirring blades A1 and A2, after a part of the target material T is effectively dispersed in the vicinity of the stirring blades A1 and A2, the dispersed part is moved to another position by the above-mentioned vortex flow. By doing so, the effect that the target material T is appropriately mixed throughout is achieved.

FIG. 9 shows the stirring blade X prepared for comparison with the stirring blades A1 and A2. The stirring blade X has a base 91, a first blade group 92a, and a second blade group 92b. The base 91 has a flat disk shape. The blade groups 92a and 92b are arranged along the outer circumference of the base 91. The first blade group 92a is composed of a plurality of blade portions 920 bent upward with respect to the base portion 91. The second blade group 92b is composed of a plurality of blade portions 920 bent downward with respect to the base portion 91. Each blade portion 920 is a substantially trapezoidal flat plate, and has an inner surface and an outer surface along the rotation direction θ. Such a stirring blade X can be obtained, for example, by cutting and bending a metal plate.

FIG. 10 shows an analysis example using numerical fluid dynamics simulation performed on the stirring blade X (the outer diameter is the same as that of the stirring blades A1 and A2) under the same conditions as the fluid analysis example shown in FIGS. 7 and 8. There is. As can be seen from FIG. 10, the flow velocity is maximum near the outer peripheral end of the stirring blade X. Further, a flow accompanied by a vortex is generated on the left and right of the rotation axis of the stirring blade X. However, the flow velocity is remarkably low in the side wall of the container 81 and the region near the liquid level of the target material T. That is, when the stirring blade X is used, stirring is mainly performed only in the mushroom-shaped region including the stirring blade X, and substantial stirring is not performed in the region other than that. As described above, it can be seen that when the stirring blades A1 and A2 are used, a larger flow velocity is obtained in a wider range of the container 81 than when the stirring blades X are used. Therefore, according to the stirring blades A1 and A2, the entire target material T can be mixed more appropriately than the stirring blades X.

First, the contribution of the forward curved portion 27 of the blade portion 20 can be mentioned as a factor for appropriately mixing the stirring blades A1 and A2. As shown in FIGS. 3 and 6, the front curved portion 27 is convex forward in the rotation direction θ. According to the research by the inventors, it is possible to smoothly move the sucked target material T outward in the radial direction while strongly sucking the target material T at the inner end 21 by such a configuration. It turned out to be. In particular, in the illustrated example, the angle formed by the blade portion 20 and the rotation direction θ at the inner end 21 is relatively small (α1 in FIG. 2 is relatively large). It was found that the material T was more strongly aspirated. Further, in the illustrated forward curved portion 27, the angle formed by the blade portion 20 and the rotational direction θ gradually increases toward the outside in the radial direction r. It has been found that this configuration is advantageous for moving the sucked target material T more smoothly outward in the radial direction. This strong suction and smooth movement is believed to be one of the reasons why the entire target material T can be mixed more appropriately.

Further, comparing the analysis example of the stirring blade A1 of FIG. 7 and the analysis example of the stirring blade A2 of FIG. 8, the light tone region (high flow velocity region) in FIG. 7 is larger than the light tone region in FIG. It is getting wider. Unlike the stirring blade A2, the stirring blade A1 is provided with a rear curved portion 28 that is convex backward in the rotation direction θ. In other words, in the rear curved portion 28, the angle formed by the blade portion 20 and the rotation direction θ gradually increases toward the outside in the radial direction r. According to the research by the inventors, it has been found that the rearwardly curved portion 28 having such a configuration can obtain the effect of more powerfully discharging the sucked target material T from the stirring blade A1 outward in the radial direction. Then, it is considered that the strengthening of the suction by the front curved portion 27 and the strengthening of the discharge by the rear curved portion 28 act synergistically to promote the mixing of the entire target material T.

Further, as described above, each blade portion 20 is tilted forward in the rotation direction θ. Thereby, it is possible to prevent the air bubbles mixed in the target material T from staying at the boundary portion (corner portion) between the rear surface 26 and the inclined surface 11. When air bubbles stay in the corners, the mixing of the target material T by the stirring blades A1 and A2 is hindered. According to the stirring blades A1 and A2, since no air bubbles remain in the corners, it contributes to the improvement of the mixing degree of the target material T.

11 and 12 show the stirring blade A3 based on the third embodiment of the present disclosure. The stirring blade A3 includes a base 1 and a pair of blade groups (upper blade group and lower blade group) 2.

FIG. 11 is a perspective view showing the stirring blade A3. FIG. 12 is a front view showing the stirring blade A3. The plan view of the stirring blade A3 is the same as the plan view of the stirring blade A1 (FIG. 3).

The stirring blade A3 is attached to, for example, the stirring device B3 shown in FIG. The stirring device B3 includes a container 81, a rotating shaft 82, and a driving unit 83. The container 81 contains the target material T. A part of the rotating shaft 82 is inserted into the target material T of the container 81, and the stirring blade A3 is attached to the lower end thereof. The drive unit 83 rotates the rotating shaft 82 in the axial direction z, and includes, for example, an electric motor. The other components of the stirring device B3 are not particularly limited, and a housing for supporting the container 81 and the driving unit 83, a control unit for controlling the driving of the driving unit 83, and the like may be appropriately provided. ..

The base 1 of the stirring blade A3 supports the upper and lower blade groups 2. The base 1 has an outer peripheral end 10 and a pair of inclined surfaces (upper inclined surface and lower inclined surface) 11. The outer peripheral end 10 is located at the center of the base 1 in the axial direction z, and is circular in a plan view. Further, the outer peripheral end 10 forms a boundary between the upper and lower blade groups 2. The upper and lower inclined surfaces 11 are provided so as to sandwich the outer peripheral end 10 in the axial direction z. The upper inclined surface 11 is tapered upward, and the lower inclined surface 11 is tapered downward. In the illustrated example, each inclined surface 11 is composed of side surfaces of a truncated cone (truncated cone).

Each blade group 2 is composed of a plurality of blade portions 20 arranged in the rotation direction θ. As shown in FIG. 12, the plurality of blade portions 20 of each blade group 2 are arranged in a predetermined range in the axial direction z. Further, the plurality of blade portions 20 of the upper blade group 2 are provided at positions deviated from the plurality of blade portions 20 of the lower blade group 2 in the circumferential direction θ. Therefore, in one example, the plurality of blade portions 20 of the upper blade group 2 are configured not to overlap with the plurality of blade portions 20 of the lower blade group 2 in the axial direction z. The configuration of each blade portion 20 is the same as that of the blade portion 20 of the stirring blade A1 described above.

In the illustrated example, the number of the plurality of blade portions 20 constituting each blade group 2 is 4. Further, in each blade group 2, the four blade portions 20 are arranged at equal pitches in the circumferential direction θ, and are separated by 90 degrees in the circumferential direction θ.

In the examples shown in FIGS. 11 and 12, the blade portion 20 of the upper blade group 2 is arranged at a position displaced by 45 degrees (90 degrees / 2) in the rotation direction θ with respect to the blade portion 20 of the lower blade group 2. ing.

FIG. 14 shows the stirring blade A4 based on the fourth embodiment of the present disclosure. The illustrated stirring blade A4 includes a pair of upper and lower blade groups 2 like the stirring blade A3 described above, and is used by being attached to, for example, a stirring device B3 (FIG. 13). The configuration of each blade portion 20 is the same as that of the blade portions 20 of the stirring blades A1 and A3 described above, and has a front curved portion 27 and a rear curved portion 28. The plan view of the stirring blade A4 is the same as the plan view of the stirring blade A1 (FIG. 3). In the stirring blade A4, the number of the plurality of blade portions 20 constituting the upper and lower blade groups 2 is the same as each other. Further, the plurality of blade portions 20 of the upper blade group 2 are provided at the same positions as the plurality of blade portions 20 of the lower blade group 2 in the rotation direction θ.

FIG. 15 shows the stirring blade A5 based on the fifth embodiment of the present disclosure. The illustrated stirring blade A5 includes a pair of upper and lower blade groups 2. The configuration of each blade portion 20 is the same as that of the stirring blade A2 described above, and has a front curved portion 27, but does not have a rear curved portion 28. The plan view of the stirring blade A5 is the same as the plan view of the stirring blade A2 (FIG. 6). The plurality of blades 20 of the upper blade group 2 are arranged at positions shifted by 45 degrees (90 degrees / 2) from the plurality of blades 20 of the lower blade group 2 in the rotation direction θ.

Next, the operations of the stirring blades A3 to A5 and the stirring device B3 will be described.

16 to 18 show an analysis example using the numerical fluid dynamics simulation of stirring by the stirring blades A3 to A5. As in the case of FIGS. 7 and 8, each arrow indicates the direction of the flow of the target material at that point (rotation direction θ component is not taken into consideration), and the shade in the figure corresponds to the flow velocity of the target material. It shows the flow velocity distribution of the target material (rotation direction θ component is not considered). The lighter the color, the higher the flow velocity (the maximum flow velocity in the white region), and the darker the color, the lower the flow velocity (the lowest flow velocity in the black region). The flow velocity ratio between adjacent regions is 2.15. The conditions of this analysis are as follows. The inner diameter of the container 81 is 210 mm. The target material T is a high-viscosity non-Newtonian fluid (sodium carboxymethyl cellulose 1.7 wt%), and the liquid depth is 158 mm. Stirring blades A3 (FIG. 16), A4 (FIG. 17) and A5 (FIG. 18) are arranged substantially in the center of the target material T. The rotation speed (peripheral speed) of the stirring blades A3 to A5 is 10 m / s.

When the stirring blades A3 to A5 rotate in the direction θ, the target material T also causes a rotational flow in the same direction. Further, as can be understood from FIGS. 16 to 18, the flow of the target material T toward the stirring blades A3 to A5 is confirmed from above and below the stirring blades A3 to A5. Further, a flow is confirmed from the axial z center (near the outer peripheral end 10) of the stirring blades A3 to A5 toward the outward r in the radial direction. Further, this flow becomes a flow toward the liquid level of the target material T or the bottom surface of the container 81 along the side wall of the container 81. As a result of such a flow, two vortices are generated on each of the left and right sides of the rotation axis of the stirring blades A3 to A5. This vortex-accompanied flow mainly contributes to the mixing of the target material T. Further, the flow velocity is maximum in the vicinity of the stirring blades A3 to A5, particularly in the vicinity of the outer peripheral end 10. Such a locally high flow velocity mainly contributes to the dispersion of the target material T.

FIG. 19 shows an analysis example using numerical fluid dynamics simulation for the stirring blade X (FIG. 9) having the same outer diameter as the stirring blades A3 to A5 under the same conditions as the fluid analysis examples shown in FIGS. 16 to 18. Is shown. As shown in FIG. 19, the flow velocity is maximum near the outer peripheral end of the stirring blade X. Further, two vortices are observed on both the left and right sides of the rotation axis of the stirring blade X. However, the flow velocity is remarkably low in the side wall of the container 81, the liquid level of the target material T, and the region near the bottom surface of the container 81. From this, it can be seen that the mixing by the stirring blades A3 to A5 is appropriately performed in a wider range of the container 81 as compared with the mixing by the stirring blades X.

As a factor of the high degree of mixing by the stirring blades A3 to A5, the contribution of the front curved portion 27 of each blade portion 20 can be mentioned as in the stirring blades A1 and A2. The strong suction and smooth movement by the forward curved portion 27 are considered to be one of the factors that cause the mixing of the entire target material T.

Comparing the fluid analysis examples of the stirring blades A3 and A4 shown in FIGS. 16 and 17 with the fluid analysis examples of the stirring blades A5 shown in FIG. Is wider than the area of light tones in FIG. As a factor for this, as described above, the stirring blades A3 and A4 have a rear curved portion 28. That is, it is considered that the strengthening of the suction by the front curved portion 27 and the strengthening of the discharge by the rear curved portion 28 act synergistically to promote the mixing of the entire target material T.

20 to 23 show an analysis example using other numerical fluid dynamics simulations of stirring by the stirring blades A3 to A5 and the stirring blade X. The conditions for these analyzes are the same as in the cases of FIGS. 16 to 19, the inner diameter of the container 81 is 210 mm, and the target material T is a high-viscosity non-Newtonian fluid (sodium carboxymethyl cellulose 1.7 wt%) having a liquid depth of 158 mm. Is used. Stirring blades A3 to A5 and stirring blades X are arranged substantially in the center of the target material T. The rotational peripheral speeds of the stirring blades A3 to A5 and the stirring blade X are 10 m / s. In these analysis examples, a plurality of granular markers are added to the target material T. Each black dot in the figure represents an individual marker. The number of markers is 1000. In the initial stage, the markers are arranged in a substantially disk-shaped region directly above the stirring blades A3 to A5 and the stirring blades X. Specifically, the initial placement region of the marker has a depth of 40 to 50 mm from the liquid surface of the target material T, and is within a circle having a diameter of 60 mm centered on the rotation axis in the lateral direction. The marker tracking time is from the time when the marker is present in the above-mentioned initial range to 0.8168 s later, which corresponds to the time for the stirring blades A3 to A5 and the stirring blade X to rotate 6.5 times.

First, in the analysis examples (stirring blades A3 to A5) shown in FIGS. 20 to 22, markers are distributed in a wider range of the target material T than in the analysis examples (stirring blades X) shown in FIG. 23. In particular, in the analysis example shown in FIG. 23, there are almost no black spots indicating markers near the side surface of the container 81 or the liquid level of the target material T. On the other hand, in the analysis examples shown in FIGS. 20 to 22, a large number of markers are present near the side surface of the container 81 and near the liquid level of the target material T. It is considered that this is an effect due to the stirring blades A3 to A5 having the forward curved portion 27 as described with reference to FIGS. 16 to 19.

Next, when the analysis example of FIG. 20 (stirring blade A3) and the analysis example of FIG. 21 (stirring blade A4) are compared, there is a difference in the number of markers existing below the stirring blade A3 and the stirring blade A4. Specifically, the number of markers existing below the stirring blade A3 is 110, while the number of markers existing below the stirring blade A4 is 47. This difference is considered to be due to the following reasons.

The stirring blades A3 and the stirring blades A4 both have a pair of upper and lower inclined surfaces 11 on the base portion 1, and each inclined surface 11 is provided with a plurality of blade portions 20 in the same manner. Further, each blade portion 20 discharges the target material T outward in the radial direction r, and the discharged flow also has a velocity component toward the blade group 2 located on the opposite side in the axial direction z. There is. As described above, in the stirring blade A3, the upper and lower blade groups 2 are deviated by half a pitch from each other in the rotation direction θ. Therefore, in the stirring by the stirring blade A3, the axial z components of the target material T discharged from the upper and lower blade groups 2 are relatively unlikely to interfere with each other. That is, in the axial direction z, the flow from one blade group 2 toward the other blade group 2 side is not hindered. In the observation of the mixed state using the stirring blade A3, a relatively large flow accompanied by a vortex moves in the axial direction z in the entire container 81 beyond the position where the stirring blade A3 is provided (the position of the outer peripheral end 10). It was confirmed that the phenomenon (that is, traversing the inside of the container 81) occurs periodically. This is preferable for promoting the mixing of the entire target material T as compared with the mixed state due to the existence of vortices separated vertically from each other in the axial direction z (without moving in the vertical direction). On the other hand, in the stirring blade A4, since the upper and lower blade groups 2 coincide with each other in the rotation direction θ, it is difficult to expect that the same effect as that of the stirring blade A3 is obtained. From this, it is considered that the stirring by the stirring blade A3 moved more markers downward in the axial direction z.

It is considered that the longitudinal flow in the container 81 generated by the stirring of the stirring blade A4 is weaker than the longitudinal flow generated by the stirring of the stirring blade A3. On the other hand, by merging the flows discharged from the upper and lower blade groups 2, the effect of generating a flow in a wider range in the radial direction r can be expected. This is suitable for appropriately stirring the target material T when the inner diameter of the container 81 is large.

Further, when the analysis example (stirring blade A3) of FIG. 20 and the analysis example (stirring blade A5) of FIG. 22 are compared, the number of markers existing below the stirring blade A3 is 110, whereas the stirring blade A5 The number of markers below is 72. This difference is considered to be the effect of the stirring blade A3 having the rear curved portion 28 as described above. In the stirring blade A5, since the upper and lower blade groups 2 are provided with a half pitch deviation from each other in the rotation direction θ, a larger number of markers are moved downward than in the analysis example of the stirring blade A4. I understand.

FIG. 24 shows a stirring device B3 using the stirring blade A3. The illustrated stirring device B3 includes two rotating shafts 82, and a stirring blade 84 in addition to the stirring blade A3.

The two rotation shafts 82 are rotationally driven by the drive unit 83, respectively. The length and rotation speed of the two rotation shafts 82 can be appropriately set. In the illustrated example, the two rotating shafts 82 are parallel to each other, and the rotating shaft 82 provided at the center (plan view) of the container 81 is longer than the other rotating shaft 82. The stirring blade 84 is larger than the stirring blade A3 (in a plan view) and is arranged near the bottom of the container 81. In a plan view, the center of the stirring blade 84 coincides with the center of the container 81. Depending on the size of the stirring blade 84 with respect to the container 81, the center of the stirring blade 84 may be arranged so as to be separated from the center of the container 81. The stirring blade 84 is provided, for example, for the purpose of promoting mixing of the entire target material T in the container 81.

In the example shown in FIG. 24, the stirring blade A3 is provided at a position offset from the center of the container 81 to the side wall of the container 81 in a plan view, and is located above the stirring blade 84 in the axial direction z. There is. Further, the stirring blade 84 has a plurality of blades (two in the illustrated example) extending in the horizontal direction from the lower end of the central rotation shaft 82. Each blade has a length that does not interfere with the inner surface of the container 81, and is longer than the separation distance between the two rotating shafts 82 in the illustrated example. As an example, without particular limitation, the number of rotations per unit time during driving is higher for the central rotation shaft 82 (extended stirring blade 84) than for the other rotating shaft 82 (extending stirring blade A3). Is set to be less than.

The degree of dispersion and the degree of mixing of the target material T can also be improved by the stirring device B3 having the above configuration. Further, by using the stirring blade 84 and the stirring blade A3 in combination, the target material T housed in the larger capacity container 81 can be appropriately mixed and dispersed.

As described above, according to the stirring blades A1 to A5 of the present disclosure, it is possible to significantly improve the mixing degree of the target material T as compared with the stirring blades X (FIG. 9). In order to improve the dispersity of the target material T, it is preferable to increase the rotation speed of the stirring blades A1 to A5. In this respect, the mixing effect of the target material T by the stirring blades A1 to A5 can be sufficiently maintained even if the rotation speed of the stirring blades A1 to A5 is increased. Therefore, according to the stirring blades A1 to A5 and the stirring devices B1 and B3, both the dispersity and the mixing degree of the target material T can be improved.

The stirring blade and the stirring device according to the present disclosure are not limited to the above-described embodiment. The specific configuration of each part of the stirring blade and the stirring device according to the present disclosure can be freely redesigned.

Claims (6)

A stirring blade that rotates around the axis
A base attached to a rotating shaft that defines the axis, and
A plurality of first blade portions provided on the first side of the base portion in a direction parallel to the axial center and arranged around the axial center are provided.
The plurality of first blade portions are connected to the inner and outer ends in the radial direction perpendicular to the axis, and the blade surface having the tip as the outer edge, and are connected to the inner end and convex forward in the rotational direction. Has a forward curved portion, which is
The stirring blade further includes a plurality of second blade portions, and the stirring blade further includes a plurality of second blade portions.
The base, the shaft and the first side with respect to a direction parallel to the heart has a second side opposite to the second blade portion of the plurality, and the provided on the second side Arranged around the axis,
The plurality of second blade portions are connected to the inner and outer ends in the radial direction perpendicular to the axis, and the blade surface having the tip as the outer edge, and are connected to the inner end and convex forward in the rotational direction. Has a forward curved portion, which is
The first side and the second side of the base portion are formed into truncated cones that are tapered in directions opposite to each other in a direction parallel to the axis .
The base has a first inclined surface formed by the side surface of the truncated cone on the first side and a second inclined surface formed by the side surface of the truncated cone on the second side.
The plurality of first blade portions are provided on the first inclined surface, and the plurality of second blade portions are stirring blades provided on the second inclined surface. The stirring blade according to claim 1, wherein each of the first blade portions has a rear curved portion that is connected to the front curved portion outward in the radial direction and is convex rearward in the rotational direction. The stirring blade according to claim 1 or 2, wherein each of the first blades is tilted so as to be positioned forward in the rotational direction so as to be separated from the base in a direction parallel to the axis. The stirring blade according to claim 3, wherein the inclination angle of each of the first blades with respect to the direction parallel to the axis is larger toward the inward in the radial direction. The stirring blade according to any one of claims 1 to 4, wherein the plurality of first blades are different in position in the rotation direction from the plurality of second blades. The stirring blade according to any one of claims 1 to 5,
A container that houses the object to be agitated and
A rotating shaft inserted into the container and to which the stirring blade is attached,
A stirrer.

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