CN109310961B

CN109310961B - Stirring blade and stirring device

Info

Publication number: CN109310961B
Application number: CN201780035206.XA
Authority: CN
Inventors: 金泽贤次郎; 西村充展; 西川明宏; 春藤晃人; 新田茂弘; 古市尚
Original assignee: Primix Corp
Current assignee: Primix Corp
Priority date: 2016-06-09
Filing date: 2017-05-25
Publication date: 2021-08-17
Anticipated expiration: 2037-05-25
Also published as: JP6858184B2; KR102275224B1; CN109310961A; JPWO2017212935A1; KR20190016554A; WO2017212935A1

Abstract

The invention provides a stirring blade rotating around a specified axis used in a stirring device. The stirring blade includes a base portion and a plurality of blade portions. The plurality of blade portions are disposed on the same side of the base portion and are arranged around the axis. Each of the plurality of blade portions includes: an inner end in a radial direction perpendicular to the axis; and a front curved portion connected to the inner end and projecting forward in the rotational direction. The stirring blade having such a structure can appropriately stir the material to be stirred, and is advantageous in improving the degree of dispersion and the degree of mixing of the material to be stirred.

Description

Stirring blade and stirring device

Technical Field

The invention relates to a stirring blade and a stirring device.

Background

Stirring devices for mixing a plurality of substances with each other are known. For example, patent document 1 listed below discloses an example of a stirring device using a stirring blade. The conventional stirring blade is attached to the tip of a shaft that is rotationally driven, and a mixture to be stirred ("target material") is contained in a predetermined container. The target material is stirred by rotating the stirring blade in the container.

Generally, in a conventional stirring apparatus, in the vicinity of a stirring means (the stirring blade or the like), a target material is sufficiently stirred, and different substances are well mixed with each other (high dispersion degree). On the other hand, at a position away from the stirring unit, the stirring of the target material is insufficient, and the degree of dispersion is low. As a result, the degree of dispersion in the conventional stirring apparatus varies depending on the position, and the overall quality of the target material is not uniform (i.e., the degree of mixing is low).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 10-180073

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been accomplished in view of the above problems. Accordingly, one of the technical problems of the present invention is to provide a stirring blade and a stirring device capable of improving both the degree of dispersion and the degree of mixing of a target material as compared with the conventional art.

Means for solving the problems

According to a first aspect of the present invention, there is provided an agitating blade that rotates about an axis. The stirring blade is provided with: a base; and a plurality of first blade portions provided on a first side of the base portion and arranged around the axis. Each of the plurality of first blade portions includes: an inner end in a radial direction perpendicular to the axis; and a front curved portion connected to the inner end and projecting forward in the rotational direction.

Preferably, each of the first blade portions has a rear curved portion that is continuous with the front curved portion on the outer side in the radial direction and that protrudes rearward in the rotational direction.

Preferably, each of the first blade portions is inclined so as to be located further forward in the rotation direction than the base portion in a direction parallel to the axial center.

Preferably, an inclination angle of each of the first blade portions with respect to a direction parallel to the axial center is larger toward an inner side in the radial direction.

Preferably, the stirring blade further includes a plurality of second blade portions, and the base portion has a second side opposite to the first side. The plurality of second blade portions are disposed on the second side and arranged around the axis.

Preferably, the plurality of first blade portions are located at positions different from the plurality of second blade portions in the rotational direction.

Preferably, the base portion has a first inclined surface and a second inclined surface tapered in opposite directions to each other. The plurality of first blade portions are provided on the first inclined surface, and the plurality of second blade portions are provided on the second inclined surface.

A second aspect of the present invention provides a stirring device comprising: the stirring blade of the first aspect described above; a container for receiving a stirring object; and a rotating shaft inserted into the container, wherein the stirring blade is attached to the rotating shaft.

Further features and advantages of the present invention will become apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

Drawings

Fig. 1 is a perspective view showing a stirring blade according to a first embodiment of the present invention.

Fig. 2 is a front view showing a stirring blade according to a first embodiment of the present invention.

Fig. 3 is a plan view showing a stirring blade according to a first embodiment of the present invention.

Fig. 4 is a sectional view showing a stirring device using a stirring blade according to a first embodiment of the present invention.

Fig. 5 is a perspective view showing a stirring blade according to a second embodiment of the present invention.

Fig. 6 is a plan view of a stirring blade according to a second embodiment of the present invention.

Fig. 7 is a diagram showing a stirring state of the stirring blade of the first embodiment.

Fig. 8 is a diagram showing a stirring state of the stirring blade of the second embodiment.

Fig. 9 is a perspective view showing a stirring blade of a comparative example.

FIG. 10 is a view showing a stirring state of a stirring blade of a comparative example.

Fig. 11 is a perspective view showing a stirring blade according to a third embodiment of the present invention.

Fig. 12 is a front view showing a stirring blade according to a third embodiment of the present invention.

Fig. 13 is a cross-sectional view showing an example of a stirring device using a stirring blade according to a third embodiment of the present invention.

Fig. 14 is a perspective view showing a stirring blade according to a fourth embodiment of the present invention.

Fig. 15 is a perspective view showing a stirring blade according to a fifth embodiment of the present invention.

Fig. 16 is a diagram showing a stirring state of the stirring blade of the third embodiment.

Fig. 17 is a diagram showing a stirring state of the stirring blade of the fourth embodiment.

Fig. 18 is a diagram showing a stirring state of the stirring blade of the fifth embodiment.

Fig. 19 is a diagram showing a stirring state of the stirring blade of the comparative example.

Fig. 20 is a diagram showing the flow trace analysis result of the marker stirred by the stirring blade of the third embodiment.

Fig. 21 is a diagram showing the flow trace analysis result of the marker stirred by the stirring blade of the fourth embodiment.

Fig. 22 is a diagram showing the flow trace analysis result of the marker stirred by the stirring blade of the fifth embodiment.

FIG. 23 is a graph showing the flow trace analysis results of the marker stirred by the stirring blade of the comparative example.

Fig. 24 is a sectional view showing another example of the stirring device using the stirring blade of the third embodiment.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, "stirring" is not particularly limited, and may include "dispersing" and "mixing". Dispersion refers to the microscopic distribution of other substances (e.g., powders or other liquids) in a chemically single phase substance (e.g., a liquid). The term "mixing" means that the entire dispersion degree of the target material is made uniform. For example, it is assumed that the object material is composed 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 distributed in (at least a part of) the liquid a ("dispersion") and that a predetermined fluidity is generated in the target material so that the distribution state of the powder B is the same (or substantially the same) at any place of the target material ("mixing").

Fig. 1 to 3 show a stirring blade according to a first embodiment of the present invention. The illustrated stirring blade a1 includes a base 1 and a blade group 2.

Fig. 1 is a perspective view showing the stirring blade a 1. Fig. 2 is a front view showing the stirring blade a 1. Fig. 3 is a plan view showing the stirring blade a 1. In fig. 1 and 3, the direction (circumferential direction) in which the stirring blade a1 rotates is represented by θ. In fig. 2, the direction in which the stirring blade a1 rotates is indicated by an arrow marked below the stirring blade a 1. In these figures, a direction (axial direction) parallel to the rotation axis of the stirring blade a1 is denoted by z, and a direction (radial direction) perpendicular to the axial direction z is denoted by r.

The stirring blade a1 is attached to, for example, a stirring device B1 shown in fig. 4. The stirring device B1 includes a container 81, a rotary shaft 82, a driving portion 83, and a shaft seal 85. The container 81 contains the stirred target material T. The rotary shaft 82 extends vertically through the bottom of the container 81, and has an agitating blade a1 mounted at its upper end. 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, but prevents the target material T from leaking from the container 81 to the outside. The driving unit 83 includes, for example, a motor to rotate the rotary shaft 82 around a predetermined axis parallel to the axial direction z. Other components of the stirring device B1 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 provided as appropriate.

The stirring blade a1 is not particularly limited, and is formed of a material suitable for the material T to be stirred, such as metal or resin. Examples of the metal forming the stirring blade a1 include stainless steel. The stirring blade a1 may be formed integrally with the base 1 and the blade group 2, or may be formed by combining a plurality of parts formed separately. As a means for attaching the stirring blade a1 to the rotating shaft 82, a well-known engaging mechanism, coupling mechanism, or the like can be used. Further, a part of the stirring blade a1 may be fixed (e.g., bonded) to the rotary shaft 82 in advance, and the other 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 may be appropriately selected depending on the size of the container 81, the viscosity of the target material T, and the like. For 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 is circular in plan view (viewed in the axial direction z). 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 has a circular shape in plan view. The inclined surface 11 is provided above the outer peripheral end 10. The dimension r in the radial direction becomes smaller the further the inclined surface 11 is in the axial direction z. In other words, the inclined surface 11 is tapered upward. In the illustrated example, the base 1 has a truncated cone shape (truncated cone) as a whole, and the inclined surface 11 is formed by a side surface of the truncated cone.

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 1, and are arranged at intervals in the rotation direction θ. In the present embodiment, a plurality of blade portions 20 are provided on 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 blade portions constituting the blade group 2 is not particularly limited. In the present embodiment, the blade group 2 is composed of 4 blade portions 40. These 4 blade portions 20 are arranged at equal intervals in a plan view, and are separated from each other by 90 degrees in the rotation direction θ.

Each blade 20 has an inboard end 21, an outboard end 22, a base end 23, a tip end 24, a front side 25, a rear side 26, a front curved portion 27, and a rear curved portion 28. The inner end 21 is located at the innermost side in the radial direction r of the blade 20, and is a linear or curved edge having a predetermined length. In the present embodiment, the inner ends 21 of the plurality of blade portions 20 are spaced apart from each other in the rotation direction θ. Outer end 22 is located on the outermost side in radial direction r of blade 20, and has a straight 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 plan view. That is, neither the base 1 nor the blade 20 protrudes outward in the radial direction r beyond the other. In another example, at least 1 blade 20 may protrude outward in the radial direction r from the base 1 or may retract inward in the radial direction r from the base 1.

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

Front side surface 25 of each blade 20 is a surface located forward in the rotation direction θ, and rear side surface 26 is a surface located rearward.

The front curved portion 27 is continuous with the inner end 21 and projects forward in the rotation direction θ in plan view. More specifically, the front curved portion 27 has a shape that protrudes further forward in the rotational direction θ than a virtual straight line connecting both ends of the front curved portion 27 in the radial direction r. The rear curved portion 28 is continuous with the front curved portion 27 on the outer side in the radial direction r, and is a portion projecting rearward in the rotational direction θ in plan view. More specifically, the rear curved portion 28 has a shape that protrudes rearward in the rotational direction θ with respect to a virtual straight line connecting both ends of the rear curved portion 28 in the radial direction r. In fig. 1 and 3, the ranges of the front curved portion 27 and the rear curved portion 28 are indicated by dashed-dotted lines with arrows, respectively. In the illustrated example, the tip end 24 is provided at a portion of the blade 20 that substantially constitutes the front curved portion 27, and has a shape that protrudes forward in the rotation direction θ in a plan view, as shown in fig. 3. The base end 23 is provided at a portion constituting the front curved portion 27 and the rear curved portion 28, respectively, and has an S-shape in plan view as shown in fig. 3. The range of the front curved portion 27 and the rear curved portion 28 and the degree of curvature thereof are not particularly limited.

In the present embodiment, each blade 20 is inclined so as to be located further forward in the rotation direction θ than the base 1 in the axial direction z. In the present embodiment, the inclination angle of blade 20 with respect to axial direction z increases inward in radial direction r. More specifically, as shown in FIG. 2, an angle α 1 formed by inboard end 21 of blade 20 and axial direction z is greater than an angle α 2 formed by outboard end 22 of blade 20 and axial direction z. Therefore, the angle of the front curved portion 27 with the axial direction z is larger than the angle of the rear curved portion 28 with the axial direction z.

Fig. 5 and 6 show a stirring blade according to a second embodiment of the present invention. The illustrated stirring blade a2 is different from the stirring blade a1 in the structure of the blade unit 20. Fig. 5 is a perspective view showing the stirring blade a 2. Fig. 6 is a plan view of the stirring blade a 2.

In the present embodiment, each blade 20 has only 1 curved portion, i.e., the front curved portion 27, and no rear curved portion 28. As shown in fig. 6, the entire blade 20 is formed of a front curved portion 27 in a plan view. The relative relationship between the plurality of paddle portions 20 in the stirring blade a2 and the structure of the base portion 1 are substantially the same as those of the stirring blade a 1. The stirring blade a2 was the same as the stirring blade a1, and was attached to and used in the stirring device B1 (fig. 4).

Next, the operation of the stirring blades a1, a2 and the stirring device B1 will be described.

Fig. 7 and 8 show an analysis example in which the agitation of the agitating blades a1 and a2 is analyzed by a hydrodynamic numerical simulation. In these figures, a plurality of arrows are marked corresponding to a plurality of points. Each arrow indicates the flow direction of the target material at that point (where the rotation direction θ component is not within the consideration). In addition, the gradations in the figure correspond to the flow velocity of the object material, and represent the flow velocity distribution of the object material (in which the rotation direction θ component is not within the consideration range). The lighter the color, the greater the relative flow rate (white areas with the greatest flow rate), and the darker the color, the lesser the relative flow rate (black areas with the least flow rate). The flow rate ratio between adjacent zones was 2.15. The conditions of this analysis are as follows. The inner diameter of the container 81 was 126 mm. The target material T was a high viscosity non-Newtonian fluid (sodium carboxymethylcellulose 1.7 wt%) with a liquid depth of 89.8 mm. The bottom center of the container 81 is provided with a stirring blade a1 (fig. 7) or a2 (fig. 8). The rotational speed (peripheral speed) of the stirring blades A1 and A2 was 10 m/s.

When the stirring blades a1, a2 rotate, the target material T flows in the rotation direction θ. As can be understood from the arrows in fig. 7 and 8, the target material T flows downward along the axial direction z from above the stirring blades a1 and a2 (and near the liquid level) toward the stirring blades a1 and a2, and then flows radially outward r along the bottom of the container 81 from the lower ends (near the outer peripheral end 10) of the stirring blades a1 and a 2. The target material T also flows upward, i.e., in the direction of the liquid surface, along the side wall of the container 81. By this flow, a large vortex is formed in the container 81. In fig. 7 and 8, there are 2 swirls symmetrical with respect to the rotational axes of the stirring vanes a1 and a 2. The flow generated accompanying such a vortex mainly contributes to the mixing of the target material T. In addition, the flow velocity is maximum near the stirring vanes a1, a2, particularly near the outer peripheral end 10 (see white region). Thus, the locally significant increase in the flow velocity mainly contributes to the dispersion of the target material T. In this way, after a part of the target material T is effectively dispersed in the vicinity of the stirring blades a1 and a2 by the stirring blades a1 and a2, the dispersed part is moved to another position by the above-mentioned vortex flow, and the target material T as a whole is appropriately mixed.

Fig. 9 shows the stirring blade X for comparison with the stirring blades a1, a 2. The stirring blade X has a base 91, a first blade group 92a, and a second blade group 92 b. The base 91 is a flat disc shape. The

blade groups

92a and 92b are arranged along the outer periphery of the base portion 91. The first blade group 92a is formed of a plurality of blade portions 920 bent upward with respect to the base portion 91. The second blade group 92b is formed of a plurality of blade portions 920 bent downward with respect to the base portion 91. Each blade 920 is a substantially trapezoidal flat plate having an inner surface and an outer surface along the rotation direction θ. Such a stirring blade X is obtained by cutting and bending a metal plate, for example.

Fig. 10 shows an analysis example in which the stirring blade X (having the same outer diameter as the stirring blades a1 and a 2) was analyzed by a hydrodynamic numerical simulation under the same conditions as the fluid analysis example shown in fig. 7 and 8. As can be seen from fig. 10, the flow velocity is maximum near the outer peripheral end of the stirring blade X. Further, a vortex is generated on the left and right sides of the rotation axis of the stirring blade X. However, in a region near the side wall of the container 81 and the liquid surface of the target material T, the flow rate is significantly reduced. That is, when the stirring blade X is used, stirring is mainly performed in the mushroom-shaped region including the stirring blade X, and substantial stirring is not performed in the other region. From this, it was found that a large flow rate can be achieved in a wider range of the container 81 by using the stirring blades a1 and a2 than by using the stirring blade X. Therefore, the stirring blades a1 and a2 can more appropriately mix the entire target material T than the stirring blade X.

The main reason for the appropriate mixing by the stirring blades a1 and a2 is primarily the contribution of the front curved portion 27 of the paddle portion 20. As shown in fig. 3 and 6, the front curved portion 27 projects forward in the rotation direction θ. As a result of the studies by the inventors, it has been found that the object material T can be attracted strongly at the inner end 21 and smoothly moved outward in the radial direction r by such a configuration. In particular, in the illustrated example, although the angle formed by the blade 20 of the inner end 21 and the rotation direction θ is relatively small (α 1 in fig. 2 is relatively large), the target material T can be attracted more strongly by this. In the illustrated front curved portion 27, the angle formed by the blade portion 20 and the rotation direction θ gradually increases as the angle increases outward from r. This structure is found to be advantageous in moving the attracted target material T more smoothly to the radial direction r outside. This strong attraction and smooth movement are considered to be one cause of being able to mix the target material T more appropriately.

In addition, comparing the analysis example of the stirring blade a1 in fig. 7 with the analysis example of the stirring blade a2 in fig. 8, the light-tone region (region where the flow velocity is high) in fig. 7 is wider than the light-tone region in fig. 8. Unlike the stirring blade a2, the stirring blade a1 is provided with a rear curved portion 28 that protrudes rearward in the rotational direction θ. In other words, in the backward curved portion 28, the angle formed by the blade section 20 and the rotation direction θ gradually increases outward in the radial direction r. As a result of the study by the inventors, it has been found that the rear curved portion 28 having such a configuration can discharge the sucked target material T more strongly outward in the radial direction r from the agitating blade a 1. The suction is intensified by the front curved portion 27, and the discharge is intensified by the rear curved portion 28, and the two complement each other, thereby promoting the mixing of the entire target material T.

As described above, each blade 20 is inclined forward in the rotation direction θ. This can prevent air bubbles mixed into the target material T from staying at the boundary (corner) between the rear surface 26 and the inclined surface 11. The air bubbles staying at the corner prevent the mixing of the target materials T by the stirring blades a1 and a 2. The agitating blades a1 and a2 prevent air bubbles from remaining in the corners, and thus contribute to an improvement in the degree of mixing of the target material T.

Fig. 11 and 12 show a stirring blade a3 according to a third embodiment of the present invention. The stirring blade a3 includes a base 1, a pair of blade groups (upper blade group and lower blade group) 2.

Fig. 11 is a perspective view showing the stirring blade a 3. Fig. 12 is a front view showing the stirring blade a 3. 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, a stirring device B3 shown in fig. 13. The stirring device B3 includes a container 81, a rotation shaft 82, and a driving portion 83. The container 81 is for receiving the target material T. A part of the rotating shaft 82 is inserted into the target material T in the container 81, and a stirring blade a3 is attached to the lower end thereof. The driving unit 83 rotates the rotary shaft 82 around the axial direction z, and includes, for example, a motor. 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 provided as appropriate.

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 has a circular shape in plan view. The outer peripheral end 10 is 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 formed by a side surface of a truncated cone (truncated cone).

Each blade group 2 is composed of a plurality of blade portions 20 aligned in the rotation direction θ. As shown in fig. 12, the plurality of blade portions 20 of each blade group 2 are arranged within a predetermined range in the axial direction z. In addition, the plurality of blade portions 20 of the upper blade group 2 are provided at positions shifted 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 and the plurality of blade portions 20 of the lower blade group 2 do not overlap each other in the axial direction z. The structure of each paddle unit 20 is the same as that of the paddle unit 20 of the stirring paddle a1 described above.

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

In the example of fig. 11 and 12, blade portion 20 of upper blade group 2 is arranged at a position shifted by 45 degrees (90 degrees/2) from blade portion 20 of lower blade group 2 in rotation direction θ.

Fig. 14 shows a stirring blade a4 according to a fourth embodiment of the present invention. The illustrated stirring blade a4 includes a pair of upper and lower blade groups 2, similar to the stirring blade A3 described above, and is attached to and used in, for example, a stirring device B3 (fig. 13). The paddle units 20 have the same configuration as the paddle units 20 of the stirring blades a1 and A3, and include 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 blade portions 20 constituting the upper and lower blade groups 2 is the same. In addition, 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 rotational direction θ.

Fig. 15 shows a stirring blade a5 according to a fifth embodiment of the present invention. The illustrated stirring blade a5 includes a pair of upper and lower blade groups 2. Each paddle unit 20 has the same configuration as the stirring paddle a2, and has a front curved portion 27 and no 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 blade portions 20 of the upper blade group 2 are arranged at positions shifted by 45 degrees (90 degrees/2) from the plurality of blade portions 20 of the lower blade group 2 in the rotational direction θ.

Next, the operation of the stirring blades A3 to a5 and the stirring device B3 will be described.

Fig. 16 to 18 show an analysis example in which the agitation of the agitating blades A3 to a5 was analyzed by a hydrodynamic numerical simulation. As in fig. 7 and 8, each arrow indicates the flow direction of the target material at that point (the rotation direction θ component is not within the range of consideration), and the gradation in the graph indicates the flow velocity distribution of the target material corresponding to the flow velocity of the target material (the rotation direction θ component is not within the range of consideration). The lighter the color, the greater the relative flow rate (white areas with the greatest flow rate), and the darker the color, the lesser the relative flow rate (black areas with the least flow rate). The flow rate ratio between adjacent zones was 2.15. The conditions of this analysis are as follows. The inner diameter of the container 81 was 210 mm. The target material T was a high viscosity non-Newtonian fluid (sodium carboxymethylcellulose 1.7 wt%) with a liquid depth of 158 mm. The stirring blades A3 (fig. 16), a4 (fig. 17), and a5 (fig. 18) are disposed substantially at the center of the target material T. The rotational speeds (peripheral speeds) of the stirring vanes A3 to A5 were 10 m/s.

When the stirring blades A3 to a5 rotate in the direction θ, the target material T also flows in the same direction. As can be understood from fig. 16 to 18, the target materials T flow from above and below the agitating blades A3 to a5 toward the agitating blades A3 to a 5. Then, the mixture flows from the axial center z (near the outer peripheral end 10) of the stirring blades A3 to a5 outward in the radial direction r. Then, the liquid flows along the side wall of the container 81 toward the liquid surface of the target material T or the bottom surface of the container 81. By such a flow, 2 swirls are generated on the left and right sides of the rotation axis of the stirring blades A3 to a5, respectively. The flow generated accompanying this swirl mainly contributes to the mixing of the target material T. The flow velocity is maximum in the vicinity of the stirring vanes A3 to a5, particularly in the vicinity of the outer peripheral end 10. Such a locally faster flow rate is mainly advantageous for the dispersion of the target material T.

Fig. 19 shows an analysis example in which the stirring vanes X (fig. 9) having the same outer diameters as the stirring vanes A3 to a5 were analyzed by a hydrodynamic numerical simulation under the same conditions as the fluid analysis examples shown in fig. 16 to 18. As shown in fig. 19, the flow velocity is maximum near the outer peripheral end of the stirring blade X. Further, 2 swirls are present on both the left and right sides of the rotation axis of the stirring blade X. However, the flow rate is significantly reduced in a region near the side wall of the container 81 or the liquid surface of the target material T and the bottom surface of the container 81. From this, it was found that the stirring blades A3 to a5 can properly mix in a wider range of the container 81 than the stirring blade X.

The main reason why the stirring blades A3 to a5 achieve high mixing degrees is the contribution of the front curved portions 27 of the respective paddle portions 20, similar to the stirring blades a1 and a 2. The strong suction and the smooth movement of the front curved portion 27 are considered to be one cause of the entire mixing of the target material T.

In addition, comparing the fluid analysis example of the stirring vanes A3, a4 shown in fig. 16 and 17 with the fluid analysis example of the stirring vane a5 shown in fig. 18, the light-tone region (region where the flow velocity is high) in fig. 16 and 17 is wider than the light-tone region in fig. 18. This is because the stirring vanes A3, a4 have the rear curved portions 28 as described above. That is, the suction is intensified by the front curved portion 27, and the discharge is intensified by the rear curved portion 28, and the two portions supplement each other, thereby promoting the mixing of the entire target material T.

Fig. 20 to 23 are analysis examples in which the stirring by the stirring vanes A3 to a5 and the stirring vane X was analyzed by another mode of the hydrodynamic numerical simulation. The conditions for these analyses were the same as those in FIGS. 16 to 19, and a high-viscosity non-Newtonian fluid (sodium carboxymethylcellulose 1.7 wt%) having a liquid depth of 158mm was used as the target material T, with the inner diameter of the vessel 81 being 210 mm. The stirring blades A3 to A5 and the stirring blade X are disposed substantially at the center of the target material T. The rotational peripheral speeds of the stirring vanes A3 to A5 and the stirring vane X were 10 m/s. In these analysis examples, a plurality of particulate markers are added to the target material T. Each black dot in the figure represents each marker. The number of labels was 1000. The marker was located in a substantially disk-shaped region immediately above the kneading blades A3 to A5 and the kneading blade X in the initial stage. Specifically, the initial arrangement region of the marker is within a circle having a depth of 40 to 50mm from the liquid surface of the target material T and a diameter of 60mm with the rotation axis as the center in the lateral direction. The marker tracing time was 0.8168s from the start of the addition of the marker in the above-mentioned initial range, which corresponds to the time for which the stirring blades A3 to A5 and the stirring blade X rotated 6.5 revolutions.

First, in the analysis examples (the stirring blades A3 to a5) shown in fig. 20 to 22, the markers are distributed in a larger range of the target material T than in the analysis example (the stirring blade X) shown in fig. 23. In particular, in the analysis example shown in fig. 23, there are substantially no black spots indicating the markers near the side surface of the container 81 or near the liquid surface of the target material T. In contrast, in the analysis examples shown in fig. 20 to 22, many markers are present near the side surface of the container 81 or near the liquid surface of the target material T. As described with reference to fig. 16 to 19, this is the effect achieved by the agitating blades A3 to a5 having the front curved portion 27.

Then, when the analysis example (stirring blade A3) of fig. 20 and the analysis example (stirring blade a4) of fig. 21 were compared, the difference between the amounts of the markers under the stirring blade A3 and the stirring blade a4 was observed. Specifically, the number of markers under the stirring vane A3 was 110, and the number of markers under the stirring vane a4 was 47. The reason for this difference is as follows.

The stirring blade A3 and the stirring blade a4 are the same in that each of the stirring blade A3 and the stirring blade a4 has a pair of upper and lower inclined surfaces 11 in the base portion 1, and a plurality of blade portions 20 are provided on each inclined surface 11. Further, the blade portions 20 discharge the target material T outward in the radial direction r, and the discharged fluid also has a velocity component toward the blade group 2 located on the opposite side in the axial direction z. As described above, in the stirring blade a3, the upper and lower blade groups 2 are shifted from each other by half pitch in the rotation direction θ. Therefore, the axial z-components of the target material T discharged from the upper and lower blade groups 2 are less likely to interfere with each other during the stirring by the stirring blade a 3. I.e. does not impede the flow in the axial direction z from one blade group 2 to the other blade group 2 side. When the mixing state using the stirring blade A3 was observed, it was found that a phenomenon in which a large vortex generated by the vortex moves axially z (i.e., passes vertically through the inside of the container 81) in the entire container 81 beyond the position where the stirring blade A3 is provided (the position of the outer peripheral end 10) occurs periodically. This is more advantageous in promoting the mixing of the entire target material T than in a mixed state in which vortices are present that are separated from each other vertically in the axial direction z (do not move vertically). On the other hand, in the stirring blade a4, the upper and lower blade groups 2 coincide with each other in the rotation direction θ, and therefore it is difficult to achieve the same effect as the stirring blade A3. Accordingly, it is understood that more markers can be moved in the downward direction z by stirring with the stirring blade a 3.

Further, the longitudinal flow in the container 81 by the stirring blade a4 is weaker than the longitudinal flow by the stirring blade A3. On the other hand, by merging the fluids discharged from the upper and lower blade groups 2, a flow can be generated in a wider range in the radial direction r. This is suitable for appropriately stirring the target material T in the case where the inner diameter of the container 81 is large.

In addition, comparing the analysis example (stirring blade A3) of fig. 20 with the analysis example (stirring blade a5) of fig. 22, the number of markers present under the stirring blade A3 was 110, and the number of markers present under the stirring blade a5 was 72. As described above, this difference is caused by the stirring blade a3 having the rear curved portion 28. Further, it was found that the stirring blade a5 was provided such that the upper and lower blade groups 2 were shifted from each other by half the pitch in the rotation direction θ, and that more markers than those of the analysis example of the stirring blade a4 were moved downward.

FIG. 24 shows a stirring apparatus B3 using a stirring blade A3. The illustrated stirring device B3 includes 2 rotating shafts 82, and a stirring blade A3 and a stirring blade 84.

The 2 rotation shafts 82 are driven to rotate by the driving unit 83. The length and the rotation speed of the 2 rotation shafts 82 can be set as appropriate. In the illustrated example, 2 rotation axes 82 are parallel to each other, and the rotation axis 82 provided at the center (when viewed from above) of the container 81 is longer than the other rotation axis 82. The stirring blade 84 is larger than the stirring blade a3 (in plan view), and is disposed near the bottom of the container 81. The center of the stirring blade 84 coincides with the center of the container 81 in a plan view. Further, depending on the size of the stirring blade 84 relative to the container 81, the center of the stirring blade 84 may be disposed away from the center of the container 81. The stirring blade 84 is provided, for example, to promote mixing of the entire target material T in the container 81.

In the example of fig. 24, the stirring blade a3 is provided at a position offset from the center of the container 81 in plan view toward the side wall of the container 81, and is located above the stirring blade 84 in the axial direction z. In addition, the stirring blade 84 has a plurality of blades (2 in the example of the figure) extending in the horizontal direction from the lower end of the central rotating shaft 82. Each blade is provided to have a length not interfering with the inner surface of the container 81, and in the illustrated example, the pitch between the rotating shafts 82 is greater than 2. The number of revolutions per unit time during driving is not particularly limited, and the center rotary shaft 82 (and the stirring blade 84) is smaller than the other rotary shaft 82 (and the stirring blade a3), for example.

The stirring device B3 having the above-described structure can also improve the degree of dispersion and mixing of the target material T. Further, by using the stirring blade 84 and the stirring blade a3 in combination, the target materials T contained in the container 81 having a larger capacity can be appropriately mixed and dispersed.

As described above, the agitating blades a1 to a5 of the present invention can significantly improve the degree of mixing of the target material T as compared with the agitating blade X (fig. 9). In order to increase the degree of dispersion of the target materials T, the rotation speeds of the stirring blades a1 to a5 are preferably increased. In this regard, even when the rotational speeds of the stirring blades a1 to a5 are set to high speeds, the mixing effect of the target materials T by the stirring blades a1 to a5 is sufficiently maintained. Therefore, the agitating blades a1 to a5 and the agitating devices B1 and B3 can improve the degree of dispersion and mixing of the target material T at the same time.

The stirring blade and the stirring device of the present invention are not limited to the above-described embodiments. Various design modifications can be freely made to the specific structure of each part of the stirring blade and the stirring device of the present invention.

Claims

1. An agitating blade for rotation about an axis, comprising:

a base;

a plurality of first blade portions provided on a first side of the base portion and arranged around the axis; and

a plurality of second blade portions formed on the first blade portion,

the plurality of first blade portions each have: an inner end in a radial direction perpendicular to the axis; and a front curved portion connected to the inner end and projecting forward in the rotational direction,

the base portion has a second side opposite the first side, the plurality of second blade portions are disposed on the second side and aligned about the axis,

the base portion has a first inclined surface and a second inclined surface tapered in opposite directions to each other, the plurality of first blade portions are provided on the first inclined surface, and the plurality of second blade portions are provided on the second inclined surface.

2. The stirring blade according to claim 1, wherein:

each of the first blade portions has a rear curved portion that is continuous with the front curved portion on the outer side in the radial direction and that protrudes rearward in the rotational direction.

3. The stirring blade according to claim 1 or 2, wherein:

each of the first blade portions is inclined so as to be located further forward in the rotation direction than the base portion in a direction parallel to the axis.

4. The stirring blade according to claim 3, wherein:

the inclination angle of each of the first blade portions with respect to the direction parallel to the axial center increases toward the inside in the radial direction.

5. The stirring blade according to claim 1 or 2, wherein:

the plurality of first blade portions are different in position from the plurality of second blade portions in the rotation direction.

6. A stirring device, comprising:

the stirring blade of any one of claims 1 to 5;

a container for receiving a stirring object; and

a rotating shaft inserted into the container, the stirring blade being mounted to the rotating shaft.