JP7531459B2 - Powder Mixer - Google Patents

Description

The technical field of this specification relates to a powder mixer that has a rotating container and mixes multiple types of powders in the rotating container.

As a powder mixer equipped with a rotating container and mixing multiple types of powders in the rotating container, a powder mixer equipped with stirring blades that contact the inner peripheral wall surface of the rotating container is known from the following Patent Document 1. This powder mixer can uniformly mix and stir multiple types of powders by rotating the rotating container and rotating the stirring blades relative to the rotating container.

JP 2018-187566 A

However, the conventional powder mixer with a rotating container described in Patent Document 1 requires cleaning of both the rotating container and the agitating blades, and further requires detaching the agitating blades from the rotating container before and after cleaning, making cleaning cumbersome.

The problem that the technology of this specification aims to solve has been made in consideration of the above points, and aims to provide a powder mixer that can uniformly mix and stir multiple types of powder and can be easily cleaned.

A powder mixer according to an embodiment of the present specification is a powder mixer including a cylindrical rotating container that contains powder, rotates in a circumferential direction, and has a rotation shaft whose axial direction is in the up-down direction,
The rotary container is characterized in that the lower part is closed and the inner bottom wall surface of the rotary container is provided with two or more guide surfaces having different inclination angles formed in the radial direction from the vicinity of the center of the bottom wall surface.

According to the powder mixer according to the embodiment of the present specification, the cylindrical rotating container has a rotating shaft with the vertical direction as the axial direction, so that when mixing and stirring, the powder in the rotating container moves in the radial direction by centrifugal force by rotating the rotating container. At this time, since the bottom wall surface of the rotating container is provided with an inclined guide surface, the powder being mixed and stirred moves in the radial direction along the guide surface and moves along the side wall surface of the rotating container in the inclination direction of the guide surface. The powder being mixed and stirred circulates inside the rotating container as if it is pushed by the bottom wall surface by the powder moving one after another. Since the guide surface has two or more different types with different inclination angles on the bottom wall surface, the powder being mixed and stirred is mixed by two or more different stirring methods depending on the difference in inclination angle. Since the powder is mixed by two or more different stirring methods, the powder mixer according to the embodiment can mix the powder in a complex manner, and as a result, the powder can be mixed and stirred uniformly. In addition, the powder mixer of the embodiment mixes and stirs multiple types of powder uniformly by rotating the rotating container, and since the only part that the powder comes into contact with is the inner wall of the rotating container, it can be easily cleaned.

Here, in the powder mixer, the corners that form the intersection between the guide surface and the inner side wall surface of the rotating container can be rounded to form chamfered portions.

This allows the powder moving in the radial direction to move smoothly from the guide surface to the side wall surface by the chamfered portion, allowing the powder to be mixed and stirred more uniformly.

In addition, in the powder mixer, the inclination angle can be in the range of 0 to 25 degrees radially upward from the horizontal plane.

With this, the powder being mixed and stirred moves radially along the guide surface and also moves upward, moving to the side wall surface or top wall surface of the rotating container and then dropping to the bottom wall surface, repeating this cycle. This makes it possible to mix and stir multiple types of powder uniformly more efficiently.

In addition, in the powder mixer, a cone-shaped central protrusion protruding inwardly of the rotating container may be formed on the rotation axis at the center of the bottom wall surface.

This allows the powder around the rotating shaft, where the centrifugal force caused by rotation is small, to move in the radial direction due to the cone-shaped central protrusion, so the powder can be mixed and stirred more efficiently and uniformly.

The powder mixer may also be provided with a connecting surface that connects two or more of the guide surfaces with different inclination angles, and the corners that form the intersection between the guide surface and the connecting surface may be rounded to form chamfered portions.

This makes it possible to smooth the movement of the powder during mixing and stirring, and also improves the ease of cleaning the powder mixer.

The powder mixer according to the embodiment of this specification can mix and stir powder uniformly and can be easily cleaned.

FIG. 2 is a perspective view of the powder mixer according to the embodiment, seen from above. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 2 is a cross-sectional view taken along line III-III in FIG. 1, and shows an image of the trajectory of powder particles during stirring. 4A is a cross-sectional perspective view taken along line IVA-IVA in FIG. 1, and FIG. 4B is a cross-sectional view taken along line IVB-IVB in FIG. 4A. 3 is a cross-sectional view taken along line VV in FIG. 2. 6 is a cross-sectional view taken along line VI-VI in FIG. 2. 7 is a cross-sectional view taken along line VII-VII in FIG. 2. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 2. This is an image diagram in which Figures 5 to 8 are superimposed.

The powder mixer according to the embodiment of the present specification will be described below with reference to the drawings. However, the technology of the present specification is not limited to these embodiments. As shown in FIG. 1, the powder mixer according to the embodiment has a cylindrical rotating container 1, a rotation axis RA with the vertical direction as the axial direction, and mixes powder P (FIG. 3) by rotating around the rotation axis RA. In this specification, the orientation of the powder mixer is as shown in FIG. 1, with the side having the top wall surface 27 as the top and the side having the bottom wall surface 21 as the bottom. In the drawings, U indicates the top and D indicates the bottom. The rotation direction is the rotation direction when the powder mixer is viewed from above. In addition, the inside or outside may be expressed based on the inside of the rotating container 1 of the powder mixer.

The rotating container 1 forming the powder mixer is made of stainless steel, is cylindrical, and is closed at the bottom by a container wall 2 and at the top by the container wall 2 except for an opening 3, and is a container in which the inside is where powder P is mixed. The ratio of the inner diameter and height of the rotating container 1 is diameter:height = 10:7, which provides excellent mixing properties for powder P. In terms of specific size, the inner diameter of the rotating container 1 is 30 cm, and the height is 21 cm.

A base (not shown) is provided below (outside) the center of the container wall 2 on the bottom wall of the rotating container 1, and is connected to a power machine (not shown) that rotates the rotating container 1. An opening 3 for putting in and taking out powder is provided around the center of the container wall 2 on the top wall of the rotating container 1, and a lid (not shown) is attached to the opening 3 so that it can be opened and closed.

As shown in Figures 2 to 4, the inner bottom wall surface 21 of the rotating container 1 is formed with a conical central projection 25 that protrudes upward on the rotation axis RA and has an apex 251 on the rotation axis RA, and four types of guide surfaces 22 with different inclination angles α in the radial direction from the central projection 25. The bottom wall surface 21 also has a planar connecting surface 23 that connects adjacent guide surfaces 22, and a chamfered portion 236 in which the corners that form the intersection lines between the guide surfaces 22 and the connecting surface 23 are rounded. The chamfered corners 236 smooth the movement of the powder P during mixing and stirring, and improve the workability when cleaning the powder mixer.

As shown in Figures 4 to 8, the radially outer end of the guide surface 22 intersects with the side wall surface 26, and the corner that forms the intersection line between the guide surface 22 and the side wall surface 26 is rounded on the outside of the corner to form a chamfered portion 226. This allows the powder P that moves radially outward due to centrifugal force to move smoothly from the guide surface 22 to the side wall surface 26.

As shown in Figures 5 to 9, the guide surface 22 has four different inclination angles α. The inclination angle α of the guide surface 22 is an elevation angle from the horizontal plane (a plane perpendicular to the rotation axis RA) to the radially upward direction, and four types are provided: guide surface 221 at 0° (Figure 5), guide surface 222 at 5° (Figure 6), guide surface 223 at 10° (Figure 7), and guide surface 224 at 15° (Figure 8). The guide surface 22 has different inclination angles, so that the distance L to the side wall surface varies (Figure 9, distances L1 to L4), with distance L1 of the 0° guide surface 221 being the shortest and distance L4 of the 15° guide surface 224 being the longest. As shown in FIG. 2, the guide surfaces 22 are provided with different angles at 30° intervals in the circumferential direction with respect to the bottom wall surface 21, and the 0° guide surface 221 and the guide surfaces (222, 223, or 224) with inclination angles exceeding 0° (5°, 10°, or 15°) are alternately arranged on the bottom wall surface 21. Specifically, in the clockwise direction from the line V-V in FIG. 2, the 0° guide surface 221 (FIG. 5), the 10° guide surface 223 (FIG. 7), the 0° guide surface 221 (FIG. 5), the 5° guide surface 222 (FIG. 6), the 0° guide surface 221 (FIG. 5), and the 15° guide surface 224 (FIG. 8) are provided in that order for half the circumference, and the remaining half the circumference is provided in the same order. By not giving regularity such as the inclination angle α to the guide surfaces 22 adjacent to each other in the circumferential direction, the powder P is mixed in a complex manner, thereby improving the mixing efficiency.

The central projection 25 is conical in shape and is provided on the rotation axis RA of the bottom wall surface 21, with the apex 251 protruding upward. The diameter of the base 252 of the central projection 25 is 0.25 times the diameter of the inside of the rotating container 1, and the height of the central projection 25 is 0.4 times the height of the inside of the rotating container 1. The central projection 25 can move the powder P around the rotating axis, where the centrifugal force caused by rotation is small, in the radial direction, so that the powder can be mixed and stirred more efficiently and uniformly. The corners that form the intersection line between the base 252 of the central projection 25 and the bottom wall surface 21 are formed with rounded chamfered portions 256.

Next, a method for mixing powder P using the powder mixer of the embodiment will be described. For powder P, raw material powders of ultraviolet curable resin (ultraviolet curable resin A, ultraviolet curable resin B, ultraviolet absorber, silica, and color pigment) were used.

The raw material powder for the ultraviolet curing resin was poured into the rotating container 1 through the opening 3, one raw material powder at a time. The amount poured was the loosely packed bulk volume, which was 0.25 times the internal volume of the rotating container 1 (approximately 3.5 liters (approximately 1.7 kg)). The poured raw material powder (powder P) was moved radially by the central protrusion 25 inside the rotating container 1, preventing it from remaining near the rotating axis where the centrifugal force caused by the rotation is small.

After the powder P is added, the opening 3 of the rotary container 1 is closed with a lid (not shown). Next, the rotary container 1 is rotated by a power machine. The rotation speed is set to 600 rpm (10 Hz).

As the rotating container 1 rotates around the rotation axis RA, the powder P in the rotating container 1 is thrown in the radial direction by centrifugal force. At this time, the powder P rises to different heights on the side wall surface 26 and is stirred by different stirring depending on the difference in the inclination angle α of the guide surface 22, which has four types of inclination angles α (0° guide surface 221 (FIG. 5), 5° guide surface 222 (FIG. 6), 10° guide surface 223 (FIG. 7), 15° guide surface 224 (FIG. 8)). The powder P that moves on the 0° guide surface 221, which has a short distance L to the side wall surface 26, reaches the side wall surface 26 in a short time, moves slightly upward on the side wall surface 26, and falls toward the center of the container. On the other hand, the powder P that moves on the 15° guide surface 224, which has a long distance L to the side wall surface 26, reaches the side wall surface 26 in a slightly longer time, moves higher on the side wall surface 26, and falls toward the center of the container (FIG. 3). The powder P is stirred by different stirring methods, while mixing with the powder P on the circumferentially adjacent guide surfaces 22. Because the inclination angle α of the adjacent guide surfaces 22 does not have any regularity, the powder P mixes randomly, improving the stirring efficiency.

The powder mixer of the embodiment can also be modified in the following ways:

In the powder mixer of the embodiment, stainless steel is used as the material for the rotating container 1, but any material that is less abraded by powder mixing can be used for the rotating container 1, and steel materials such as carbon tool steel (JIS G 4401:2009), sintered ceramic materials, etc. can also be used.

In the powder mixer of the embodiment, the ratio of the diameter to the height of the rotating container 1 on the inside is set to 10:7, which is excellent in mixing the powder P, but if the ratio of the diameter to the height of the rotating container 1 on the inside is 10:4 to 10, the mixing of the powder P can be excellent. If the height is less than 4 relative to the diameter of 10, the height is low relative to the diameter, and there is a risk that the powder P cannot be mixed efficiently. On the other hand, if the height is more than 10 relative to the diameter of 10, the powder P does not reach the upper side of the side wall surface 26 during mixing, and the height becomes excessive, which may result in wasteful equipment. In another embodiment, the ratio of the diameter to the height of the rotating container 1 on the inside can be 10:5 to 9, and in yet another embodiment, the diameter to the height can be 10:6 to 8.

In the powder mixer of the embodiment, the inner diameter of the rotating container 1 is 30 cm, but if the inner diameter of the rotating container 1 is 10 to 100 cm, it can be made to have excellent mixing properties for the powder P.

In the powder mixer of the embodiment, the guide surface 22 has four different inclination angles α, but by providing two to eight different inclination angles α, excellent mixing efficiency can be achieved. If there are less than two inclination angles α (i.e., one angle), sufficient mixing efficiency may not be obtained. On the other hand, if there are more than eight inclination angles, it may be difficult to process the bottom wall surface 21 that includes the guide surface 22, and manufacturing the powder mixer may become difficult. In another embodiment, the inclination angle α of the guide surface 22 may be three to five different angles. The guide surface 22 may also have a wave-shaped shape that changes continuously in the circumferential direction of the bottom wall surface 21.

In the powder mixer of the embodiment, the inclination angle α of the guide surface 22 is 0 to 15°, but if the inclination angle α of the guide surface 22 is 0 to 25°, excellent mixing efficiency can be achieved. If the inclination angle α of the guide surface 22 is less than 0°, the guide surface 22 will be at a downward depression angle in the radial direction, and powder P may accumulate at the outer end of the guide surface during mixing, resulting in poor mixing efficiency. On the other hand, if the inclination angle α of the guide surface 22 exceeds 25°, the powder P may not rise sufficiently upward due to the centrifugal force of mixing. In another embodiment, the inclination angle α of the guide surface 22 can be 0 to 20°.

In the powder mixer of the embodiment, the diameter of the skirt 252 of the central protrusion 25 is 0.25 times the diameter of the inside of the rotating container 1, but if the length is 0.05 to 0.5 times the diameter of the inside of the rotating container 1, the powder can be mixed and stirred efficiently and uniformly. If the diameter of the skirt 252 of the central protrusion 25 is less than 0.05 times the diameter of the inside of the rotating container 1, it is small compared to the diameter of the inside of the rotating container 1, and there is a risk that the effect of increasing the efficiency of mixing and stirring cannot be confirmed. On the other hand, if it exceeds 0.5 times, the mixing area of the powder P on the bottom wall surface 21 (the area of the guide surface 22) becomes relatively small, and the efficiency of mixing and stirring may be inferior. In another embodiment, the diameter of the skirt 252 of the central protrusion 25 can be 0.15 to 0.3 times the diameter of the inside of the rotating container 1.

In the powder mixer of the embodiment, the height of the central protrusion 25 is 0.4 times the height of the inside of the rotating container 1, but if the length is 0.1 to 0.6 times the height of the inside of the rotating container 1, the powder can be mixed and stirred efficiently and uniformly. If the height of the central protrusion 25 is less than 0.1 times the height of the inside of the rotating container 1, it is small compared to the height of the inside of the rotating container 1, and there is a risk that the effect of increasing the efficiency of mixing and stirring cannot be confirmed. On the other hand, if it exceeds 0.6 times, it is large compared to the height of the inside of the rotating container 1, and there is a risk that maintenance such as cleaning will be poor. In another embodiment, the height of the central protrusion 25 can be 0.2 to 0.5 times the height of the inside of the rotating container 1.

In the powder mixer of the embodiment, raw material powder of ultraviolet curable resin is used as the powder P to be mixed, but the powder P is not limited to this and can also be used as metal powder used in additive manufacturing and powder metallurgy, cement-based materials such as grout, cosmetics such as foundation, food products such as mixed seasonings and pancake mix, medicines such as powdered drugs, etc.

In the powder mixer of the embodiment, the rotation speed when mixing the powder P is 600 rpm (10 Hz), but if the rotation speed is 180 to 1800 rpm (3 to 30 Hz), the powder can be mixed and stirred uniformly efficiently. If the rotation speed is less than 180 rpm (3 Hz), the centrifugal force is weak and there is a risk that sufficient mixing and stirring cannot be performed. On the other hand, if the rotation speed exceeds 1800 rpm (30 Hz), although sufficient mixing and stirring can be performed, there is a risk that the load on the powder mixer will be excessive. In another embodiment, the rotation speed when mixing the powder P can be 300 to 900 rpm (5 to 15 Hz).

DESCRIPTION OF SYMBOLS 1... Rotating container, 2... Container wall, 3... Opening part, 21... Bottom wall surface, 22... Guiding surface, 23... Connecting surface, 25... Central protrusion, 26... Side wall surface, 27... Top wall surface, 221... Guiding surface , 222... Guide surface, 223... Guide surface, 224... Guide surface, 226... Chamfer, 236... Chamfer, 251... Top, 252... Bottom, 256... Chamfer, L... Distance, P... Powder, RA ...Rotation axis, α...Inclination angle.

Claims (4)

A powder mixer including a cylindrical rotating container that contains powder, rotates in a circumferential direction, and has a rotation shaft whose axial direction is in the up-down direction,
The lower part of the rotating container is closed, and two or more kinds of guide surfaces having different inclination angles are formed on the inner bottom wall surface of the rotating container in a radial direction from the vicinity of the center of the bottom wall surface,
A powder mixer characterized in that a corner forming an intersection line between the guide surface and the inner side wall surface of the rotary container is rounded off to form a chamfered portion. A powder mixer including a cylindrical rotating container that contains powder, rotates in a circumferential direction, and has a rotation shaft whose axial direction is in the up-down direction,
The lower part of the rotating container is closed, and two or more kinds of guide surfaces having different inclination angles are formed on the inner bottom wall surface of the rotating container in a radial direction from the vicinity of the center of the bottom wall surface,
The inclination angle is in the range of 0 to 25 degrees radially upward with respect to the horizontal plane. A powder mixer including a cylindrical rotating container that contains powder, rotates in a circumferential direction, and has a rotation shaft whose axial direction is in the up-down direction,
The lower part of the rotating container is closed, and two or more kinds of guide surfaces having different inclination angles are formed on the inner bottom wall surface of the rotating container in a radial direction from the vicinity of the center of the bottom wall surface,
A powder mixer comprising: a cone-shaped central projection formed on said rotation shaft at the center of said bottom wall surface and projecting inwardly of said rotating container. A powder mixer including a cylindrical rotating container that contains powder, rotates in a circumferential direction, and has a rotation shaft whose axial direction is in the up-down direction,
The lower part of the rotating container is closed, and two or more kinds of guide surfaces having different inclination angles are formed on the inner bottom wall surface of the rotating container in a radial direction from the vicinity of the center of the bottom wall surface,
A powder mixer characterized in that a connecting surface is provided which connects two or more types of guide surfaces having different inclination angles, and a corner forming an intersection line between the guide surface and the connecting surface is rounded off to form a chamfered portion.

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