Spheroidizing device

Abstract

To provide a powder spheroidizing device which can produce spheroidized fine particles while maintaining material crushing effects.SOLUTION: A spheroidizing device 1 has a liner 3 where a large number of crushing grooves 21 are formed on its inner peripheral surface, and a rotor 4 where a large number of crushing grooves 22 are formed on its outer peripheral surface. The crushing grooves 21 and 22 of the liner 3 and the rotor 4 have the same cross-sectional shape. Each of the crushing grooves 21 and 22 has a round part 23 having an arcuate bottom surface, and an inclination part 24 extending in a circumferential direction. Radial openings 25a and 25b extending in a tangential direction are formed on both ends of the round part 23. The inclination part 24 includes a slope 26 arranged on the side of the round part 23, and a horizontal surface 27 which is arranged on the side of the adjacent crushing grooves 21 and 22 continuous to the slope 26. The spheroidizing device 1 draws a powder raw material to the crushing grooves 21 and 22 by a swirl flow generated in the round part 23, and rolls the drawn powder raw material in the round part 23 and the inclined part 24 and produces spherical fine particles.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pulverizer for obtaining fine powders such as toner for electrostatic charge image development, a negative electrode material for secondary batteries, and powder coatings, and particularly to a powder spheroidizing apparatus suitable for spheroidizing fine powder particles.

Background Art

[0002] Conventionally, for resin fine powders such as toner for electrostatic charge image development and fluororesin powder, with the demands for higher image quality in copying etc. and higher performance of dry lubricants etc., the refinement of the powder particle size has been required. In view of such demands, the applicant of the present application has created (Patent Document 1) and put into practical use a pulverizer that can pulverize a pulverized product to a particle size below the conventional pulverization limit while having a small pulverization power.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the other hand, in recent years, for fine powders such as toner, spheroidization of fine powder particles has been required for minimizing the specific surface area and improving fluidity and fillability. Also, in the negative electrode material for secondary batteries, in order to increase the amount of particles filled in a certain volume, spheroidization of the particles has been required for the purpose of improving the fillability (bulk density). At that time, even in the pulverizer of Patent Document 1, fine powder that is considerably spheroidized with a narrow particle size distribution is obtained, but the demand for spheroidization has become stricter year by year, and an apparatus capable of further spheroidization has been required.

[0005] An object of the present invention is to provide a powder spheroidizing apparatus capable of producing more spheroidized fine powder particles while maintaining the material pulverization effect as a pulverizer.

Means for Solving the Problems

[0006] The spheroidizing device of the present invention includes a liner formed in a hollow cylindrical shape with a number of pulverizing grooves formed on its inner peripheral surface, and a rotor concentrically disposed inside the liner with a gap therebetween and having a number of pulverizing grooves formed on its outer peripheral surface. The pulverizing grooves of the liner and the rotor have the same cross-sectional shape. Each pulverizing groove has a round portion with an arcuate bottom surface, and an inclined portion provided at one end side of the arc of the round portion and extending in the circumferential direction of the liner and the rotor.

[0007] In the present invention, pulverizing grooves are formed on the peripheral surfaces of the liner and the rotor, and a round portion and an inclined portion are provided in these pulverizing grooves. Thereby, rolling of the powder raw material (object to be processed) occurs and is promoted in the pulverizing grooves, and a pulverizing / angle removing action of the powder raw material particles and an action of rounding the particles occur. Due to these synergistic actions, fine powder particles with removed corners and rounded shapes are generated.

[0008] In the spheroidizing device, radiation openings extending in the tangential direction of the arc and formed at both ends of the round portion may be provided in the pulverizing groove. One end side of the radiation opening is continuously connected to the inclined portion, and an opening edge portion that extends on the peripheral surfaces of the liner and the rotor and becomes the apex of the pulverizing groove is formed at the other end side. In this case, one end side of the inclined portion may be continuously connected to the opening edge portion of the adjacent pulverizing groove, and the other end side may be continuously connected to one end side of the radiation opening.

[0009] In the spheroidizing device, the inclined portion may be provided with an inclined surface disposed on the round portion side and a horizontal surface continuously connected to the inclined surface and disposed on the side of the adjacent pulverizing groove. Also, the inclined portion may be provided with an inclined surface disposed on the round portion side and a horizontal surface continuously connected to the inclined surface and disposed on the side of the adjacent pulverizing groove. The inclined surface may be continuously connected to one end side of the radiation opening, and the horizontal surface may be continuously connected to the opening edge portion of the adjacent pulverizing groove.

[0010] Set the radius of the round part to 0.5 mm to 1.5 mm, preferably 0.8 mm to 1.2 mm, more preferably 1.0 mm, the opening angle θ1 at both ends of the radiation opening to 25° to 45°, preferably 30° to 40°, more preferably 35°, and the angle θ2 between the radiation opening and the inclined part of the adjacent grinding groove to 70° to 90°, preferably 75° to 85°, more preferably 80°.

[0011] At the opening edge, the radiation opening and the inclined part of the adjacent grinding groove may be connected by a curved surface, or one end side of the radiation opening and the inclined part may be connected by a curved surface.

[0012] Arrange the horizontal plane along the straight line connecting the top parts Z, incline the inclined plane in the radial direction of the liner and the rotor from the horizontal plane, and incline it at an angle θ3 of 5° to 20°, preferably 5° to 15°, more preferably 10° with respect to the straight line. Also, the inclined plane and the horizontal plane may be connected by a curved surface.

Advantages of the Invention

[0013] According to the spheroidizing device of the present invention, grinding grooves are formed on the circumferential surfaces of the liner and the rotor of the spheroidizing device, and a round part and an inclined part are provided in the grinding grooves. Thereby, rolling of the powder raw material can be generated and promoted in the grinding groove. Therefore, with the spheroidizing device, it is possible to grind the powder raw material and remove corners, and further spheroidize the generated fine powder particles.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described. FIG. 1 is a cross-sectional view showing the overall configuration of a powder spheroidizing apparatus (hereinafter abbreviated as the spheroidizing apparatus) according to an embodiment of the present invention. As shown in FIG. 1, the spheroidizing apparatus 1 includes a cylindrical outer box 2, a hollow cylindrical liner (stator) 3 (inner diameter radius R1) fixed inside the outer box 2, and a rotor (rotor) 4 (outer diameter radius R2) rotatably accommodated inside the liner 3. The rotor 4 is attached to a rotating shaft 5 arranged on the center line O of the liner 3 via a key 6 and a nut 7. The rotating shaft 5 is arranged concentrically with the liner 3 and is rotatably supported by bearings 8a and 8b arranged at both axial ends of the outer box 2. A pulley 9 is fixed to the end of the rotating shaft 5, and the rotating shaft 5 and the rotor 4 are integrally rotated at high speed by a belt (not shown).

[0016] A gap G is formed between the liner 3 and the rotor 4, and a pulverizing chamber 11 for pulverizing the powder raw material is formed. The pulverizing chamber 11 communicates with an inlet 12 provided at one end side (left side in FIG. 1) of the outer box 2 and an outlet 13 provided at the other end side, respectively. The powder raw material introduced from the inlet 12 is pulverized and refined in the pulverizing chamber 11 and discharged outside the machine from the outlet 13. The fine powder particles discharged outside the machine are conveyed together with the air sucked from the outlet 13 side by a blower and separated into fine powder and air by a cyclone (not shown). Thereafter, the fine powder particles are collected in a product tank under the cyclone, and the air is discharged into the atmosphere after minute dust is removed by a dust collector (bag filter).

[0017] In the spheroidizing device 1, a large number of pulverizing grooves 21 and 22 extending parallel to the center line O are provided on the inner peripheral surface of the liner 3 and the outer peripheral surface of the rotor 4, respectively. FIG. 2 is a partial cross-sectional view taken along the line A-A of FIG. 1. The pulverizing grooves 21 and 22 are continuously formed at a predetermined pitch P over the entire circumference of the inner peripheral surface of the liner 3 and the outer peripheral surface of the rotor 4. As shown in FIG. 2, the pulverizing groove 21 on the liner 3 side and the pulverizing groove 22 on the rotor 4 side are arranged in a state of being radially opposed to each other in the pulverizing chamber 11. The pulverizing grooves 21 and 22 face each other with a gap G = R1 - R2 = 2.0 to 1.0 mm, where R1 is the inner diameter radius of the liner 3 and R2 is the outer diameter radius of the rotor 4. Note that, according to the specifications of the spheroidizing device 1, R1 is appropriately set to 125 mm to 400 mm (diameter 250 to 800 mm), and R2 is appropriately set to 124 mm to 399 mm (diameter 248 mm to 798 mm).

[0018] FIG. 3 is an explanatory view showing the configuration of the pulverizing groove 22. Since the opposing pulverizing groove 21 is also formed with the same cross-sectional shape and dimensions as the pulverizing groove 22, only the pulverizing groove 22 on the rotor 4 side will be described here. As shown in FIG. 3, the pulverizing groove 22a (22) includes a round portion 23 (radius Rg = 1.0 mm) having an arcuate bottom surface, and an inclined portion 24 formed at one end of the arc of the round portion 23 (left side in FIG. 3: rear side in the rotor rotation direction, the same applies hereinafter) and extending in the circumferential direction. In the spheroidizing device 1 according to the present invention, the powder raw material is drawn into the pulverizing groove 22 by the vortex generated in the round portion 23, and is rolled and rounded by the round portion 23 and the inclined portion 24 to generate spherical fine powder particles.

[0019] At both circumferential ends of the round portion 23, there are provided radial opening portions 25a and 25b that extend in the arc tangent direction from both ends of the round portion and open radially outward in the rotor diameter direction. Here, the opening angle θ1 at both ends of the radial opening portion 25 is formed to be 35°. Further, the inclined portion 24 is composed of an inclined surface 26 and a horizontal surface 27, and the two are continuously connected at the connection portion X. The right side of the inclined surface 26 in FIG. 3 (the other end side: the front side in the rotor rotation direction, the same applies hereinafter), that is, the side not connected to the horizontal surface 27, is continuously connected to one end side of the radial opening portion 25a at the connection portion Y. The horizontal surface 27 extends along the circumferential direction from the connection portion X and is the boundary with the adjacent pulverizing groove 22b, and reaches the groove top Z which is the opening edge portion 28 of the pulverizing groove 22b.

[0020] At the groove top Z, the horizontal surface 27 of the inclined portion 24 is connected to the radial opening portion 25b (the other end side) of the adjacent pulverizing groove 22b. Here, the angle θ2 between the horizontal surface 27 and the radial opening portion 25b is formed to be 80°. Further, the distance between the groove top Z and the bottommost portion 23a of the round portion 23, that is, the depth S of the pulverizing groove 22 is 2.2 mm. On the other hand, the distance between adjacent groove tops Z is the pitch P between the pulverizing grooves 22, and this is the dimension obtained by adding the length La of the horizontal surface 27 and the distance Lb between the connection portion X and the groove top Z of the pulverizing groove 22a. Here, La = 2 mm and Lb = 8.3 mm are set, and the pitch P between the pulverizing grooves 22 is 10.3 mm.

[0021] Further, the horizontal surface 27 is arranged along a straight line L connecting the groove tops Z of the adjacent pulverizing grooves 22. The inclined surface 26 is inclined from the horizontal surface 27 toward the connection portion Y. Here, it is inclined at θ3 = 10° with respect to the straight line L and extends while inclining toward the center direction of the rotor 4 (downward in the straight line L in FIG. 3). In the case of the pulverizing groove 22, on the contrary, it is inclined from the horizontal surface 27 toward the outside in the radial direction of the liner 3.

[0022] In the spheroidizing device 1, such pulverization grooves 21 and 22 are formed continuously at the same pitch P on the entire outer peripheral surface of the rotor 4 and the entire inner peripheral surface of the liner 3, whereby pulverization and spheroidization of the powder raw material are achieved. FIG. 4 is an explanatory view showing the pulverization and spheroidization action of the powder raw material in the spheroidizing device 1 according to the present invention.

[0023] Here, when the rotor 4 rotates at a constant speed in the spheroidizing device 1, an air flow AF is generated in the gap G between the liner 3 and the rotor 4. As shown in FIG. 4, this air flow AF flows along the shape of the pulverization grooves 21 and 22, and the air flow AF that has crossed the groove apex Z is drawn into the round portion 23 of the pulverization grooves 21 and 22 by the negative pressure generated on the adjacent round portion 23 side. The air drawn into the round portion 23 has the property of flowing along its shape, and due to this action, a vortex flow VF is generated in the round portion 23. Note that the rotational speed of the vortex flow VF changes in proportion to the rotational speed of the rotor 4. For this reason, the speed of the vortex flow VF can be controlled by the rotational speed of the rotor 4, and the particle size and spheroidization effect of the generated fine powder particles can also be adjusted by the rotor rotational speed.

[0024] In the spheroidizing device 1, a particle group of powder raw material of a certain size flows in from the inlet 12 together with air. The particles PM that have flowed into the machine during operation together with air are drawn into the pulverization grooves 21 and 22 along the air flow AF due to the so-called Coandă effect and come into contact with the groove surface. The particles PM that have flowed into the pulverization grooves 21 and 22 are given a rotational motion by the vortex flow VF generated in the pulverization grooves 21 and 22 while contacting the round portion 23. The particles PM in the round portion 23 rotate by themselves due to the vortex flow VF as the rotor 4 rotates, and are accelerated by centrifugal force and move toward the inclined portion 24 side, and roll on the inclined surface 26 and the horizontal surface 27.

[0025] Particles PM that reach the end of the horizontal plane 27 are drawn into the adjacent next grinding grooves 21, 22. That is, the particles PM are rotated again by the vortex VF in the round portion 23 and accelerated by centrifugal force. Then, they move while rolling on the inclined portion 24 toward the next groove apex Z. Such an operation is continuously repeated as the rotor 4 rotates, and the grinding grooves 21, 22 gradually remove the corners of the particles PM while grinding them. Also, at this time, an action of comprehensively rounding a plurality of particles PM is also imparted.

[0026] In this case, in the grinder of Patent Document 1, particles are collided with each other by a high-speed vortex generated in a valley-shaped round portion and finely ground. However, in the spheroidizing device 1 according to the present invention, the pitch P of the grinding grooves 21, 22 is larger than that of the device of Patent Document 1, and further, a long inclined portion 24 is provided between adjacent grooves. Thereby, in the spheroidizing device 1, the particles PM come into contact with the inclined portion 24 on the surface of the rotor that rotates and roll while their corners are shaved off, and not only the fine grinding of the particles PM but also the promotion of spheroidization are achieved.

[0027] As described above, in the spheroidizing device 1, by taking a large pitch P of the grinding grooves 21, 22 and providing the round portion 23 and the inclined portion 24 in the grinding grooves 21, 22, the rolling of the particles is generated and promoted, and not only the grinding and corner removing action of the particles PM but also an action of rounding up a plurality of particles PM together occurs there. And when these actions work synergistically, particles with removed corners and rounded shapes, and spherical fine powder particles in which a plurality of particles are comprehensively rounded are generated by the spheroidizing device 1, and further spheroidization of the fine powder particles is achieved. Also, since the spheroidizing device 1 rotates the rotor 4 at a high speed, the above actions can be continuously applied to the particles PM many times, so that the powder raw material can be ground and spheroidized in a short time, and different from a batch type in which the machine is sealed for a certain period of time for processing, continuous grinding and spheroidizing processing are possible.

[0028] It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof. The above various dimensions are also an example as an embodiment, and the present invention is not limited to the above numerical values and can be appropriately changed according to the physical properties, particle size, amount, etc. of the raw materials and products. According to the experiments of the inventor, for example, the radius Rg of the round portion 23 is in the range of 0.5 mm to 1.5 mm, preferably 0.8 mm to 1.2 mm, and the angle θ1 is 25° to 45°, preferably 30° to 40°, the angle θ2 is 70° to 90°, preferably 75° to 85°, and the angle θ3 is 5° to 20°, preferably 5° to 15°, and can be set by appropriately combining them (excluding those that cannot be geometrically combined). Furthermore, the pitch P of the pulverization grooves 21 and 22 can also be changed, and changes such as doubling the number of grooves by halving the pitch P are also possible. In that case, in the spheroidizing device 1, the groove pitch P becomes larger than that of the conventional pulverizer by the amount of the inclined portion 24 provided, for example, the groove pitch that was conventionally about 3 mm is set to about 5.0 to 15 mm according to the device specifications.

[0029] In addition, it is also possible to adopt a configuration in which the horizontal plane 27 is omitted in the inclined portion 24 and only the inclined surface 26 is provided, a configuration in which the radiation openings 25a and 25b at both ends of the round portion 23 are omitted and the round portion 23 and the inclined portion 24 are directly connected, or a configuration in which the round portion 23 extends directly to the opening edge portion 28. Also, in the above embodiment, the connection portions X and Y and the groove apex Z have an angular edge structure, but these may be in an arc-shaped R shape.

[0030] On the other hand, this machine also has a pulverizing effect, and fine powder particles tend to be generated with a small particle size at high speed rotation and a coarse particle size at low speed rotation. Also, it is possible to adjust the particle size and spheroidizing effect of the generated fine powder particles by the clearance width (gap G dimension) between the liner 3 and the rotor 4. Furthermore, it is also possible to provide a refrigerant passage in the rotor and perform water cooling for the spheroidizing device 1 according to the present invention, as in Utility Model Registration No. 3140509. In addition, depending on the material and properties of the raw material, applying a sudden force at once may instead break the particles. In that case, depending on the situation, multiple units of this machine may be connected and the particles may be continuously processed while applying the spheroidizing action multiple times.

Example

[0031] Next, a pulverization example of the spheroidization apparatus according to the present invention will be described. The pulverization test results in the above-described spheroidization apparatus 1 (Figs. 1 to 4) are compared with those of a conventional pulverizer (Patent Document 1) and shown in Table 1. Also, micrographs (3000 times) of the particles in the examples and comparative examples are shown in Fig. 5.

[0032] [Table 1]

[0033] Table 1 focuses on "bulk density (loose tap)", which is one of the spheroidization evaluations. The apparatuses in each example and comparative example have the same inner and outer diameters of the pulverization chamber, and Table 1 shows experimental examples with apparatuses of the same size. In this case, the higher the numerical value of the bulk density, the better the filling rate in a certain volume, and the higher the evaluation. In particular, the value of "tap" is used as the standard for bulk density. The results in the table compare the results of Example 1 and Comparative Example 1 (Example 1), and Example 2 and Comparative Example 2 (Example 2), respectively, using materials of the same substance (natural graphite) with equivalent pulverized particle sizes. Also, Example 3 is the result of evaluating the performance of the apparatus of the present invention alone using the same material as Example 1. Note that although the materials of Example 1 and Example 2 are the same "graphite" as a substance, they are treated as different materials because they are from different origins.

[0034] As can be seen from the experimental results in Table 1, the spheroidization apparatus 1 according to the present invention has a higher bulk density than the conventional pulverizer in both loose and tap cases. That is, the loose and tap values, which were 0.2057 and 0.3962 for the conventional machine, are 0.2429 and 0.4998 (Example 1) for the spheroidization apparatus 1. Similarly, the values that were 0.2092 and 0.4262 became 0.2571 and 0.5174 (Example 2), and in both cases, the spheroidization apparatus 1 has better results. Also, although Example 3 is a single result, the particle size and peripheral speed are made comparable to those of Comparative Example 1 and Comparative Example 2. In that case as well, a processed product with a better bulk density is obtained with the apparatus of the present invention. Actually, from the micrographs shown in Fig. 5, it can be seen that the sphericity of each example is higher than that of the comparative examples, and the effect of the spheroidization apparatus according to the present invention was confirmed.

Industrial Applicability

[0035] The manufacturing method of the present invention is applicable not only to toner for electrostatic charge image development but also to the spheroidization of various fine particles used in electrode materials of lithium-ion secondary batteries, photocatalysts, cosmetics, foods, and the like.

Explanation of Symbols

[0036] 1 Spheroidization device 2 Outer box 3 Liner 4 Rotor 5 Rotation 6 Key 7 Nut 8a, 8b Bearings 9 Pulley 11 Crushing chamber 12 Inlet 13 Outlet 21 Crushing groove (liner side) 22 Crushing groove (rotor side) 22a Crushing groove 22b Crushing groove 23 Round part 23a Bottommost part 24 Inclined part 25 Radial opening 25a Radial opening 25b Radial opening 26 Slope 27 Horizontal plane 28 Opening edge AF Airflow G Gap La Horizontal plane length Lb Distance between connection part X and groove top Z O Center line P Pitch PM Particles R1 Liner inner diameter radius R2 Rotor outer diameter radius Rg Round part radius S Crushing groove depth VF Vortex X Connection part of slope and horizontal plane Y Connection part of slope and one end side of radial opening Z groove top θ1 Radiation opening opening angle θ2 Angle between the radiation opening and the inclined part θ3 Inclined surface inclination angle

Claims

1. A powder spheronizing device comprising: a liner formed in a hollow cylindrical shape and having a number of grinding grooves formed on its inner peripheral surface; and a rotor concentrically disposed inside the liner with a gap therebetween and having a number of grinding grooves formed on its outer peripheral surface, The pulverization grooves of the liner and the rotor have the same cross-sectional shape, A spheronizing device characterized in that each of the crushing grooves has a round portion with an arc-shaped bottom surface and an inclined portion provided on one end side of the arc of the round portion and extending in the circumferential direction of the liner and the rotor.

2. The sphering apparatus according to claim 1, The grinding groove has radial openings formed at both ends of the round portion and extending in a tangent direction of the arc, A sphering device characterized in that one end of the radial opening is continuously connected to the inclined portion and the other end extends to the circumferential surface of the liner and the rotor, forming an opening edge portion which becomes the top of the crushing groove.

3. The sphering apparatus according to claim 2, A sphering device characterized in that one end side of the inclined portion is continuously connected to the opening edge portion of the adjacent crushing groove, and the other end side is continuously connected to one end side of the radiation opening portion.

4. The sphering apparatus according to claim 1, A spheronizing device characterized in that the inclined portion has an inclined surface arranged on the round portion side and a horizontal surface arranged on the adjacent crushing groove side, which is continuously connected to the inclined surface.

5. The sphering apparatus according to claim 2, The inclined portion has an inclined surface arranged on the rounded portion side and a horizontal surface arranged on the adjacent crushing groove side, the horizontal surface being continuously connected to the inclined surface, A sphering device characterized in that the inclined surface is continuously connected to one end side of the radiation opening, and the horizontal surface is continuously connected to the opening edge portion of the adjacent crushing groove.

6. The sphering apparatus according to claim 1, A spheronizing apparatus characterized in that the radius of the round portion is 0.5 mm to 1.5 mm, preferably 0.8 to 1.2 mm, and more preferably 1.0 mm.

7. The sphering apparatus according to claim 2, A sphering apparatus characterized in that the opening angle θ1 of both ends of the radiation opening is 25° to 45°, preferably 30° to 40°, and more preferably 35°.

8. The sphering apparatus according to claim 2, A spheronizing apparatus characterized in that, at the opening edge portion, the angle θ2 between the radiation opening and the inclined portion of the adjacent crushing groove is 70° to 90°, preferably 75° to 85°, and more preferably 80°.

9. The sphering apparatus according to claim 2, A sphering device characterized in that, at the opening edge portion, the radiation opening and the inclined portion of the adjacent crushing groove are connected by a curved surface.

10. The sphering apparatus according to claim 2, A sphering device, characterized in that one end side of the radiation opening and the inclined portion are connected by a curved surface.

11. The sphering apparatus according to claim 5, The horizontal plane is disposed along a straight line connecting the tops of the heads, The inclined surface is inclined from the horizontal plane toward the radial direction of the liner and the rotor, and is inclined at an angle θ3 of 5° to 20°, preferably 5° to 15°, and more preferably 10° with respect to the straight line.

12. The sphering apparatus according to claim 5, A sphering device, characterized in that the inclined surface and the horizontal surface are connected by a curved surface.

Images