Air flow classifier

Abstract

Provided is a pneumatic classifier that is capable of maintaining classification precision for a prolonged period of time and that has smaller classification points. This pneumatic classifier comprises: a casing which has a ceiling wall and an annular wall that is provided contiguously to the outer rim of the ceiling wall; a classification plate which is disposed on the ceiling wall of the casing so as to have the surface thereof facing the ceiling wall; a classification chamber which is formed between the ceiling wall of the casing and the surface of the classification plate; a gas supply part which feeds gas into the classification chamber so as to generate a swirl flow therein; a raw material supply part which feeds raw material powder to the swirl flow generated within the classification chamber; a fine powder discharge port which is provided to a central part of either one of the surface of the classification plate and the ceiling wall of the casing forming the classification chamber; a coarse powder discharge port that opens along the outer periphery of the classification chamber on the side of either the ceiling wall or the surface of the classification plate facing the ceiling wall; and a groove part which is provided in the ceiling wall and / or the surface of the classification plate.

Description

[Technical Field]

[0001] The present invention relates to an air classifier that classifies raw material powder having a particle size distribution into fine powder and coarse powder at a desired particle size (classification point) by utilizing the balance between centrifugal force and drag force applied to the powder by a swirling flow formed by gas, and in particular to an air classifier that maintains classification accuracy while making the classification point smaller. [Background technology]

[0002] Currently, fine particles such as oxide fine particles, nitride fine particles, and carbide fine particles are used in the manufacture of sintered bodies such as electrical insulating materials for semiconductor substrates, printed circuit boards, and various electrical insulating parts, high-hardness, high-precision machining materials for cutting tools, dies, and bearings, functional materials for humidity sensors, and precision sintered molding materials, the manufacture of thermal sprayed parts such as engine valves and other materials that require high-temperature wear resistance, as well as fuel cell electrodes, electrolyte materials, and various catalysts, etc. The use of such fine particles improves the bonding strength and density, as well as functionality, between dissimilar ceramics or dissimilar metals in sintered bodies and thermal sprayed parts, etc.

[0003] The above-mentioned microparticles are manufactured by a chemical method in which various gases are subjected to a chemical reaction at high temperatures, or a physical method in which a substance is decomposed and evaporated by irradiation with an electron beam or a laser beam, thereby producing microparticles. The microparticles manufactured by the above-mentioned manufacturing method have a particle size distribution, and are a mixture of coarse and fine particles. When used for the above-mentioned applications, it is preferable for the microparticles to contain a small proportion of coarse particles, as this will result in better properties. Similarly, for metal microparticles, it is preferable for the metal microparticles to contain a small proportion of coarse particles, as this will result in better properties. Therefore, for example, air classifiers and powder classifiers are used which use a swirling flow to give a swirling motion to the powder and separate it into coarse powder and fine powder by centrifugal separation.

[0004] For example, Patent Document 1 describes a powder classifier into which powder having a particle size distribution is supplied by airflow transport. The powder classifier in Patent Document 1 includes a disk-shaped hollow (disk-shaped hollow portion) that is a space for classifying the supplied powder having a particle size distribution, a powder supply port that supplies the powder having a particle size distribution to the disk-shaped hollow portion, a plurality of guide vanes arranged to extend inward at a predetermined angle from the outer periphery of the disk-shaped hollow portion, a discharge portion for an air flow containing fine powder discharged from the disk-shaped hollow portion, and a collection portion for coarse powder discharged from the disk-shaped hollow portion, as well as a plurality of air nozzles that are located below the plurality of guide vanes and arranged tangentially to the outer peripheral wall of the disk-shaped hollow portion, and that blow compressed air into the coarse powder collection portion inside the disk-shaped hollow portion and return the fine powder on the coarse powder collection portion side to the disk-shaped cavity.

[0005] Patent document 2 also describes a classification device in which powder supplied from a supply port provided at the top of the device body is swirled within the device body and guided downward, and a suction tube made up of multiple tubes with a suction port at the top end is provided in the center of the device body, and small particle diameter powder from the powder being swirled and guided downward is sucked through the suction tube from the suction port. In Patent Document 2, powders having different particle sizes are separately sucked and collected through a suction pipe made up of multiple pipes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4785802 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-107698 Summary of the Invention [Problem to be solved by the invention]

[0007] The powder classifier of Patent Document 1 can classify raw material powder having a particle size distribution into fine powder and coarse powder at a desired particle size (classification point). However, the particle size of the fine powder required has recently become smaller, and there is a demand for a powder classifier with an even smaller classification point. In addition, in Patent Document 2, one raw material powder is classified in one classification operation, and powders of different particle sizes are collected in each tube constituting each of the multiple tubes through a suction tube composed of the above-mentioned multiple tubes. For this reason, in Patent Document 2, powder can be collected in each of the tubes that make up the multiple tubes, and the variation in particle size of each collected powder can be reduced, but the classification point is determined by the balance of the air volume of each suction tube, and it does not achieve a miniaturized classification point. Furthermore, when classifying powders, it is desirable to be able to stably classify them over a long period of time and to maintain the classification accuracy over a long period of time.

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide an air classifier which overcomes the problems associated with the prior art, maintains classification accuracy for a long period of time, and has a smaller classification point. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, one aspect of the present invention provides an air current classifier having a casing having a ceiling wall and an annular wall provided continuously from the outer edge of the ceiling wall, a classification plate arranged with its surface facing the ceiling wall of the casing, a classification chamber formed between the ceiling wall of the casing and the surface of the classification plate, a gas supply unit that supplies gas into the classification chamber to generate a swirling flow, a raw material supply unit that supplies raw material powder to the swirling flow generated in the classification chamber, a fine powder discharge port provided in the center of one of the ceiling wall of the casing and the surface of the classification plate that constitute the classification chamber, a coarse powder discharge port that opens along the outer periphery of the classification chamber on either the ceiling wall or the surface of the classification plate facing the ceiling wall, and a groove portion provided in at least one of the ceiling wall and the surface of the classification plate.

[0010] It is preferable to have at least one of a first cylindrical portion provided at the fine powder discharge port and a second cylindrical portion provided on the surface of the classification plate of the classification chamber opposite the first cylindrical portion and with a predetermined gap therebetween. Preferably, the diameter of the first cylindrical portion is different from the diameter of the second cylindrical portion. It is preferable that a slope is formed on at least one of the top wall of the casing and the surface of the classification plate, and that a groove is provided on the slope. It is preferable that a slope is formed on at least one of the periphery of the first cylindrical portion of the ceiling wall of the casing and the periphery of the second cylindrical portion on the surface of the classification plate, and that a groove is provided on the slope.

[0011] It is preferable that the fine powder discharge port has a circular shape, and the groove portion is provided concentrically with the fine powder discharge port. The grooves are preferably provided on the ceiling wall and the surface of the classification plate. It is preferable that the fine powder discharge port is circular, the groove is provided concentrically with the fine powder discharge port, and the groove provided in the ceiling wall faces the groove provided on the surface of the classification plate. Of the ceiling wall and the surface of the classification plate, on the side where the fine powder discharge outlet is located, a groove is provided concentrically with the fine powder discharge outlet along the periphery of the fine powder discharge outlet, and on the side where the fine powder discharge outlet is not located, a concentric groove is provided opposite the concentric groove provided in the area around the fine powder discharge outlet, and it is preferable that the concentric groove provided on the side where the fine powder discharge outlet is located and the concentric groove provided on the side where the fine powder discharge outlet is not located are located at the same position in a direction perpendicular to the direction in which the ceiling wall of the casing of the classification chamber and the surface of the classification plate face each other. It is preferable that a plurality of grooves are provided along the periphery of the fine powder discharge port.

[0012] It is preferable that the ceiling wall has a first cylindrical portion and the surface of the classification plate has a groove portion. It is preferable that the surface of the classification plate has a second cylindrical portion and that a groove portion is provided in the top wall. The inclined surface is preferably inclined so that the height of the classification chamber gradually increases from the outside toward the center of the classification chamber. The inclined surface is preferably inclined so that the height of the classification chamber decreases from the outside toward the center of the classification chamber.

[0013] The raw material supply section is preferably connected to either the ceiling wall of the casing that defines the classification chamber or the surface of the classification plate, and supplies raw material powder to the swirling flow generated in the classification chamber. The raw material supply unit preferably has a jet nozzle for supplying raw material powder to the swirling flow generated in the classification chamber. The gas supply unit preferably has a plurality of air nozzles, and the air nozzles are preferably arranged at equal intervals in the circumferential direction of the classification chamber along the outer edge of the classification chamber. The gas supply section preferably has a plurality of guide vanes, and the guide vanes are preferably arranged at equal intervals in the circumferential direction of the classification chamber along the outer edge of the classification chamber. [Effects of the Invention]

[0014] According to the present invention, when raw material powder having a particle size distribution is classified into fine powder and coarse powder, the classification point can be made smaller than before while maintaining classification accuracy for a long period of time. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional view showing a first example of an air classifier according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic view showing an example of a groove portion of the first example of the air classifier according to the embodiment of the present invention. [Figure 3] FIG. 4 is a schematic view showing another example of the groove portion of the first example of the air classifier according to the embodiment of the present invention. [Figure 4] FIG. 3 is a schematic cross-sectional view showing a second example of an air classifier according to an embodiment of the present invention. [Figure 5] FIG. 3 is a schematic partial cross-sectional view showing a third example of an air classifier according to an embodiment of the present invention. [Figure 6] FIG. 10 is a schematic partial cross-sectional view showing a fourth example of an air classifier according to an embodiment of the present invention. [Figure 7]FIG. 10 is a schematic partial cross-sectional view showing a fifth example of an air classifier according to an embodiment of the present invention. [Figure 8] FIG. 10 is a schematic partial cross-sectional view showing a sixth example of an air classifier according to an embodiment of the present invention. [Figure 9] FIG. 10 is a schematic partial cross-sectional view showing a seventh example of an air classifier according to an embodiment of the present invention. [Figure 10] FIG. 10 is a schematic partial cross-sectional view showing an eighth example of an air classifier according to an embodiment of the present invention. [Figure 11] FIG. 13 is a schematic partial cross-sectional view showing a ninth example of an air classifier according to an embodiment of the present invention. [Figure 12] FIG. 20 is a schematic partial cross-sectional view showing a tenth example of an air classifier according to an embodiment of the present invention. [Figure 13] FIG. 16 is a schematic cross-sectional view showing an eleventh example of an air classifier according to an embodiment of the present invention. [Figure 14] FIG. 4 is a schematic cross-sectional view showing a first air current classifier for comparison. [Figure 15] 10 is a graph showing the results of classification. [Figure 16] FIG. 2 is a schematic diagram showing ceramic particles after classification by the air classifier of the present invention. [Figure 17] FIG. 10 is a schematic diagram showing ceramic particles after classification by a first air current classifier for comparison. [Figure 18] FIG. 4 is a schematic partial cross-sectional view showing a second air current classifier for comparison. [Figure 19] 10 is a graph showing the results of classification. [Figure 20] FIG. 2 is a schematic diagram showing ceramic particles after classification by the air classifier of the present invention. [Figure 21] FIG. 10 is a schematic diagram showing ceramic particles after classification by a second air current classifier for comparison. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The air classifier of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings. It should be noted that the drawings described below are illustrative for explaining the present invention, and the present invention is not limited to the drawings shown below.

[0017] (First example of an air classifier) FIG. 1 is a schematic cross-sectional view showing a first example of an air classifier according to an embodiment of the present invention, FIG. 2 is a schematic view showing an example of a groove portion of the first example of an air classifier according to an embodiment of the present invention, and FIG. 3 is a schematic view showing another example of a groove portion of the first example of an air classifier according to an embodiment of the present invention. The air classifier 10 shown in FIG. 1 classifies raw material powder having a particle size distribution into fine powder Pf and coarse powder Pc at a desired particle size (classification point) by utilizing the balance between the centrifugal force and drag force exerted on the powder by a swirling flow formed by gas.

[0018] The airflow classifier 10 shown in FIG. 1 has, for example, a cylindrical casing 12. The casing 12 has a ceiling wall 13 and an annular wall 19 provided continuously with the outer edge 13b of the ceiling wall 13. The ceiling wall 13 constitutes a circular upper disk-shaped portion 14, and the casing 12 has the upper disk-shaped portion 14. A classifying plate 16 is arranged on the ceiling wall 13 of the casing 12, i.e., the upper disk-shaped portion 14, with a predetermined gap between them and surfaces 16c facing each other. The outer shape of the classifying plate 16 is approximately circular. The upper disk-shaped portion 14 (ceiling wall 13) and the classifying plate 16 are arranged facing each other in direction H. A roughly disk-shaped classification chamber 18 is defined between the upper disk-shaped portion 14 and the classification plate 16, and the outer circumferential surface of the classification chamber 18 is closed by an annular wall 19 of the casing 12. In this manner, the classification chamber 18 is a space sandwiched between the opposing top wall 13 (surface 14c of the upper disk-shaped portion 14) and the surface 16c of the classification plate 16, and the classification chamber 18 is defined between the top wall 13 of the casing 12 and the surface 16c of the classification plate 16. In this manner, the upper disk-shaped portion 14 (ceiling wall 13) and the classification plate 16 are both members that define the space of the classification chamber 18. Within the classification chamber 18, raw material powder having a particle size distribution is separated and classified, for example, into coarse powder and fine powder.

[0019] A fine powder discharge port 14a is formed in the center of the upper disk-shaped portion 14. The fine powder discharge port 14a is in communication with the classification chamber 18. The fine powder discharge port 14a is, for example, circular. As will be described later, the raw material powder is separated in the classification chamber 18 into coarse powder and fine powder, and the fine powder is discharged through the fine powder discharge port 14a. The surface 14c of the upper disk-shaped portion 14 facing the classification chamber 18 is configured as, for example, a plane parallel to the direction W. This direction W is a direction perpendicular to the direction H. The surface 16c of the classification plate 16 facing the classification chamber 18 is configured as, for example, a plane parallel to the direction W. The surface 14c of the upper disk-shaped portion 14 and the surface 16c of the classification plate 16 are parallel to each other.

[0020] A groove 50 is provided in the first region 24a around the fine powder discharge port 14a in the upper disk-shaped portion 14. The groove 50 is recessed relative to the surface 14c of the upper disk-shaped portion 14. The groove portion 50 is arranged along the fine powder discharge port 14a and concentrically with the fine powder discharge port 14a, for example, as shown in Fig. 2. The ceiling wall 13 (upper disk-shaped portion 14) on which the fine powder discharge port 14a is provided is provided with the groove portion 50 along the periphery of the fine powder discharge port 14a and concentrically with the fine powder discharge port 14a. In the classification plate 16, a groove 51 is provided in a second region 26a facing the first region 24a around the fine powder discharge port 14a. The groove 51 is recessed into the surface 16c of the classification plate 16. In a member without an opening (for example, the classification plate 16), a concentric groove 51 is provided facing the concentric groove 50 provided in the region around the fine powder discharge port 14a. The groove 51 has the same configuration as the groove 50.

[0021] The grooves 50 of the upper disk-shaped portion 14 and the grooves 51 of the classification plate 16 are arranged opposite to each other in the direction H. For example, the concentric grooves 50 provided in the upper disk-shaped portion 14 (one member) and the concentric grooves 51 provided in the classification plate 16 (the other member) are provided at the same position in the direction W perpendicular to the direction H in which the two members of the classification chamber 18, the upper disk-shaped portion 14 and the classification plate 16, face each other. The grooves 50 and 51 both have a rectangular cross-sectional shape. The cross-sectional shape of the grooves 50 and 51 is not limited to a rectangular shape, and the bottoms may be flat, curved, or bent. For example, the cross sections may be U-shaped or V-shaped. Groove portion 51 has the same configuration as groove portion 50, with the same width in direction W and the same depth in direction H, but is not limited to this. Groove portion 50 and groove portion 51 may have different widths in direction W and different depths in direction H.

[0022] The groove 50 may be provided in the first region 24a around the fine powder discharge port 14a, and is not limited to being provided along the outer edge of the fine powder discharge port 14a. As described above, the grooves 50 and 51 are arranged concentrically with the fine powder discharge port 14a, for example, as shown in Fig. 2, but this is not limiting. For example, as shown in Fig. 3, a plurality of grooves 52 may be provided along the periphery of the fine powder discharge port 14a. The grooves 52 have, for example, circular openings. The grooves may be provided in at least one of the two opposing members, the upper disk-shaped portion 14 and the classification plate 16, that constitute the classification chamber 18. In other words, it is sufficient that the grooves are recessed in at least one of the first region 24a around the fine powder discharge port 14a and the second region 26a facing the first region 24a around the fine powder discharge port 14a.

[0023] By providing the grooves, when powder is classified, adhesion of the powder to the inside of the classification chamber 18 is suppressed. If powder adheres to the inside of the classification chamber 18, the adhered powder may become detached, but by suppressing the adhesion of the powder, the probability of the powder becoming detached can be reduced. This allows stable classification over a long period of time, and classification accuracy can be maintained over a long period of time. Moreover, the classification point can be made smaller. That is, the powder can be classified into fine powder and coarse powder at a smaller particle size. Furthermore, by providing the grooves, the speed of the powder moving from the outside of the device toward the fine powder outlet 14a can be locally suppressed, thereby making the classification point smaller. As a result, the powder can be classified into fine powder and coarse powder at a smaller particle size. As described above, the configuration is such that groove portion 50 is provided in upper disk-shaped portion 14 and groove portion 51 is provided in classification plate 16, but this is not limited to this, and it is sufficient that the configuration has at least one of groove portion 50 in upper disk-shaped portion 14 and groove portion 51 in classification plate 16.

[0024] A fine powder recovery pipe 30 is provided at the fine powder discharge port 14a so as to extend in a direction perpendicular to the surface 12a of the casing 12. This perpendicular direction is parallel to the direction H described above. The fine powder recovery pipe 30 is for discharging gas containing the fine powder Pf classified in the classification chamber 18 to the outside of the classification chamber 18 through the gap 23. An end 30c of the fine powder recovery pipe 30 opposite the classification chamber 18 is connected to a suction blower (not shown), for example, via a bag filter (not shown). The bag filter (not shown) and the suction blower (not shown) constitute a fine powder recovery device. The fine powder recovery pipe 30 constitutes a fine powder recovery section. Of the coarse powder and fine powder generated by separation of the raw material powder in the classification chamber 18, the fine powder is discharged from the fine powder discharge port 14a of the upper disk-shaped portion 14. Furthermore, there is a gap 39 between the outer end 16a of the classification plate 16 and the annular wall 19 of the casing 12. The gap 39 is located at the outer edge of the classification chamber 18. A coarse powder recovery chamber 28 having, for example, a hollow truncated cone shape is provided below the casing 12. The classification chamber 18 and the coarse powder recovery chamber 28 are connected by the gap 39. Furthermore, the outer edge of the classification chamber 18 is higher in height in direction H than the central part, and the outer edge of the classification chamber 18 expands in direction H.

[0025] The coarse powder recovery chamber 28 is used to discharge the coarse powder Pc classified in the classification chamber 18 to the outside of the classification chamber 18. A coarse powder recovery pipe (not shown) is provided in the coarse powder recovery chamber 28 to collect the classified coarse powder. A hopper (not shown) is provided at the lower end of the coarse powder recovery pipe, for example, via a rotary valve (not shown). The coarse powder Pc obtained by classifying the raw material powder in the classification chamber 18 passes through the gap 39, passes through the coarse powder recovery chamber 28, and the coarse powder recovery pipe, and is collected in the hopper. The gap 39 described above constitutes the coarse powder discharge port 66. Of the coarse powder and fine powder generated by separation of the raw material powder in the classification chamber 18, the coarse powder is discharged from the coarse powder discharge port 66. The coarse powder recovery section is constituted by the coarse powder recovery chamber 28. In the configuration of the coarse powder recovery section shown in Fig. 1, fine powder Pf is discharged from the upper disk-shaped portion 14 (one member) side, and coarse powder Pc is discharged from the gap 39 (coarse powder discharge port 66) on the classification plate 16 (the other member) side, which is located at the outer edge of the classification chamber 18. Here, the coarse powder recovery section, for example, the coarse powder recovery chamber 28, is located on either the upper disk-shaped section 14 (one member) or the classification plate 16 (the other member) facing the upper disk-shaped section 14 (one member) across the classification chamber 18, and is provided on the outer edge of the classification chamber 18 so as to communicate with the interior of the classification chamber 18, and discharges the coarse powder Pc classified in the classification chamber 18 to the outside of the classification chamber 18. The configuration of the coarse powder recovery section is not limited to the configuration shown in FIG.

[0026] A plurality of first air nozzles 34 are provided on the annular wall 19 of the casing 12 on the side of the fine powder recovery pipe 30 in the direction H. Also, a second air nozzle 36 is provided on the annular wall 19 below the first air nozzles 34 in the direction H. In other words, a plurality of second air nozzles 36 are provided. Furthermore, the cylindrical casing 12 is provided with a third air nozzle 38 below the second air nozzle 36 in the direction H. That is, a plurality of third air nozzles 38 are provided. Although not shown in detail, multiple first air nozzles 34 are provided along the outer edge of the classification chamber 18, each at a predetermined angle relative to the tangent direction of the outer edge of the classification chamber 18, and are arranged at equal intervals around the circumferential direction of the classification chamber 18, for example, six in number. Similar to the first air nozzle 34, the second air nozzle 36 and the third air nozzle 38 are also provided in plurality along the outer edge of the classification chamber 18, and are arranged, for example, six in number, at equal intervals in the circumferential direction of the classification chamber 18, while each forming a predetermined angle with respect to the tangent direction of the outer edge of the classification chamber 18. The gas supply unit has a first air nozzle 34 and a second air nozzle 36. Although the gas supply unit has the first air nozzle 34 and the second air nozzle 36, it may also be configured to have only the first air nozzle 34 or the second air nozzle 36 of the first air nozzle 34 and the second air nozzle 36.

[0027] The first air nozzle 34, the second air nozzle 36, and the third air nozzle 38 are each connected to a pressurized gas supply unit (not shown) and have a gas injection port. Gas at a predetermined pressure is supplied from the pressurized gas supply unit to the first air nozzle 34 and the second air nozzle 36, and the pressurized gas is ejected from each of them, thereby forming swirling flows that swirl in the same direction in the classification chamber 18. The gas is determined appropriately depending on the raw material powder to be classified or the purpose, and air is used, for example. When the raw material powder reacts with air, another gas that does not react with air is used appropriately. In addition, gas at a predetermined pressure is supplied from the pressurized gas supply unit to the third air nozzle 38, and the pressurized gas is ejected from the third air nozzle 38, supplying the pressurized gas to the gap 39 between the outer end 16a of the classification plate 16 and the casing 12. The number of first air nozzles 34, second air nozzles 36, and third air nozzles 38 to be provided is not limited to the above-mentioned numbers, and may be one or more, and is determined appropriately depending on the device configuration, etc. Furthermore, the second air nozzle 36 is not limited to a nozzle, but may be a guide vane or the like as described later, and is determined appropriately depending on the device configuration.

[0028] A supply pipe 42 is provided on the surface 12a of the casing 12 at a predetermined distance from the fine powder recovery pipe 30 in the direction W. The supply pipe 42 is provided on the outer edge of the casing 12. For example, a raw material supply unit 40 for supplying raw material powder Ps into the classification chamber 18 is provided above the supply pipe 42. The supply pipe 42 is, for example, hollow and frustum-shaped. The supply pipe 42 is arranged with the tip, having a smaller diameter, facing the surface 12a of the casing 12. The connection between the supply pipe 42 and the casing 12 is made of a pipe with a constant diameter. The supply pipe 42 is, for example, connected to the upper disk-shaped portion 14, and the raw material powder Ps is supplied into the classification chamber 18 through an opening 42a of the upper disk-shaped portion 14.

[0029] Next, the operation of the air classifier 10 will be described. First, a suction blower (not shown) draws air at a predetermined volume from the classification chamber 18 through the fine powder recovery pipe 30, and pressurized gas is supplied from a pressurized gas supply unit (not shown) to the first air nozzle 34 and the second air nozzle 36, respectively, to generate a swirling flow in the classification chamber 18. In this state, a predetermined amount of raw material powder Ps having a particle size distribution is supplied from the raw material supply section 40 through the opening 42 a of the upper disk-shaped section 14 to the swirling flow in the classification chamber 18 .

[0030] Because a swirling flow is formed in the classification chamber 18 due to the pressurized gas ejected from the first air nozzle 34 and the second air nozzle 36, the raw material powder Ps supplied to the classification chamber 18 from a raw material ejection nozzle (not shown) swirls within the classification chamber 18, and the raw material powder Ps is subjected to centrifugal separation within the classification chamber 18. As a result, the grooves 50 and 51 provided in the classification chamber 18 locally suppress the speed of the powder moving from the outside of the device toward the fine powder discharge port 14a, thereby reducing the classification point. This allows the powder to be classified into fine powder and coarse powder at smaller particle sizes. As a result, the coarse powder Pc, which has a larger particle size, remains in the classification chamber 18 without flowing into the fine powder recovery pipe 30 through the fine powder discharge port 14a. Meanwhile, the fine powder Pf, which is smaller than the classification point, passes through the fine powder discharge port 14a along with the air flow and is sucked and discharged from the fine powder recovery pipe 30. In this way, the fine powder Pf can be classified and recovered from the raw material powder Ps having a particle size distribution. Moreover, as described above, by providing the grooves 50 and 51, adhesion of powder to the inside of the classification chamber 18 is suppressed. Since classification can be performed stably for a long period of time, classification accuracy can be maintained for a long period of time. The particle size of the recovered fine powder Pf can be reduced.

[0031] The remainder of the raw material powder that was not discharged from the fine powder recovery pipe 30, i.e., the coarse powder Pc, passes through the gap 39 between the classification plate 16 and the annular wall 19 and falls from the classification chamber 18 into the coarse powder recovery chamber 28. Thereafter, the remainder of the raw material powder, i.e., the coarse powder Pc, is recovered via a coarse powder recovery pipe (not shown).

[0032] Depending on the air flow and other conditions, the guide vane method may be able to classify with higher precision than the air nozzle method. Therefore, the conventional guide vane method can be selected depending on the classification purpose.

[0033] In the air classifier 10, the outer circumferential portion of the substantially disk-shaped classification chamber 18 is closed by the annular wall 19, so that even if a large flow rate of pressurized gas is forcibly introduced from the first air nozzle 34 and the second air nozzle 36, the air does not leak outward in the circumferential direction of the classification chamber 18, and vortexes are not disturbed. Therefore, by increasing the amount of pressurized gas that flows in from the first air nozzle 34 to form a swirling flow in the coarse particle recovery chamber 28, in particular, it becomes possible to stably classify submicron particles. Although fine particles such as submicron particles have a tendency to agglomerate with each other, the air classifier 10 can efficiently classify them by ejecting a large flow rate of pressurized gas from the first air nozzle 34 and the second air nozzle 36. Furthermore, various types of powders can be used as raw material powders to be classified, ranging from those with low specific gravity such as silica and toner to those with high specific gravity such as metals and alumina. However, depending on the classification purpose, the second air nozzle 36 may be of a guide vane type, which has a wide setting range for the air volume.

[0034] (Second example of an air classifier) FIG. 4 is a schematic cross-sectional view showing a second example of an air classifier according to an embodiment of the present invention. In the air classifier 10a shown in FIG. 4, the same components as those in the air classifier 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10a shown in Figure 4 differs from the air classifier 10 shown in Figure 1 in that it has a cylindrical first cylindrical portion 20 and a cylindrical second cylindrical portion 22, but otherwise has the same configuration as the air classifier 10 shown in Figure 1. In the airflow classifier 10a, the upper disk-shaped portion 14 is provided with a first cylindrical portion 20 that protrudes into the classification chamber 18 along the edge of the fine powder discharge port 14a. The first cylindrical portion 20 is configured, for example, by a cylindrical member having the same inner diameter as the fine powder discharge port 14a. The first cylindrical portion 20 and the fine powder discharge port 14a are in communication. A cylindrical second cylindrical portion 22 is provided on the other member, the classification plate 16, facing the first cylindrical portion 20 so as to leave a predetermined gap 23 between them. The first cylindrical portion 20 and the second cylindrical portion 22 are arranged in the center of the classification chamber 18 in the direction W.

[0035] Like the air classifier 10 described above, the air classifier 10a can achieve a smaller classification point than conventional methods while maintaining high accuracy when classifying raw material powder having a particle size distribution into fine powder and coarse powder. Furthermore, the first cylindrical portion 20 and the second cylindrical portion 22 prevent large coarse powder Pc from flowing into the fine powder recovery pipe 30, leaving the large coarse powder Pc in the classification chamber 18. Meanwhile, fine powder Pf having a size equal to or smaller than the classification point passes through the gap 23 together with the airflow and can be sucked into the fine powder recovery pipe 30 via the fine powder discharge port 14a. This allows the particle size of the recovered fine powder Pf to be made smaller. By having the first cylindrical portion 20 and the second cylindrical portion 22, the classification points can be made smaller than before.

[0036] (Third example of an air classifier) FIG. 5 is a schematic partial cross-sectional view showing a third example of an air classifier according to an embodiment of the present invention. In the air classifier 10b shown in FIG. 5, the same components as those in the air classifier 10a shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10b shown in Figure 5 differs from the air classifier 10a shown in Figure 4 in that a fine powder discharge outlet 16b is provided on the classification plate 16, and the fine powder Pf is removed from the classification plate 16; otherwise, the air classifier 10b has the same configuration as the air classifier 10a shown in Figure 4.

[0037] In the airflow type classifier 10b, a groove 51 is provided in the second region 26a around the fine powder discharge port 16b. A groove 50 is provided in the first region 24a of the upper disk-shaped portion 14 opposite the groove 51. In the airflow type classifier 10b, the first region 24a of the upper disk-shaped portion 14 is the region facing the periphery of the fine powder discharge port 16b. Note that the position where the groove 51 is provided may be in the second region 26a around the fine powder discharge port 16b, and is not limited to being provided along the outer edge of the fine powder discharge port 16b. A fine powder recovery pipe 60 is provided at the fine powder discharge port 16b. Similar to the fine powder recovery pipe 30 (see FIG. 4), the fine powder recovery pipe 60 has an end (not shown) connected to a suction blower (not shown) via a bag filter (not shown), for example. The bag filter (not shown) and the suction blower (not shown) constitute a fine powder recovery device. The fine powder recovery pipe 60 constitutes a fine powder recovery section. The fine powder Pf is recovered through the fine powder recovery pipe 60. The air flow type classifier 10b can obtain the same effects as the air flow type classifier 10a shown in FIG. 4. In the configuration of the coarse powder recovery section shown in Figure 5, fine powder Pf (see Figure 1) is discharged from the classification plate 16 side, and coarse powder Pc (see Figure 1) is discharged from the gap 39 (coarse powder discharge port 66) on the classification plate 16 side, between the outer end 16a of the classification plate 16 and the annular wall 19 of the casing 12 (see Figure 1). 1 and 4, the fine powder Pf may be removed from the upper disk-shaped portion 14, as in the air classifiers 10 and 10a, or the fine powder Pf may be removed from the classification plate 16, as in the air classifier 10b. In the air classifier, the method for removing the fine powder Pf is not particularly limited.

[0038] (Fourth example of an air classifier) FIG. 6 is a schematic partial cross-sectional view showing a fourth example of an air classifier according to an embodiment of the present invention. In the air classifier 10c shown in FIG. 6, the same components as those in the air classifier 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10c shown in Figure 6 differs from the air classifier 10 shown in Figure 1 in that a first cylindrical portion 20 is provided on the upper disk-shaped portion 14 and a groove portion 51 is provided on the classification plate 16, but otherwise has the same configuration as the air classifier 10 shown in Figure 1.

[0039] In the air current classifier 10c, the upper disk-shaped part 14 is provided with a first cylindrical part 20 that protrudes into the classifying chamber 18 along the edge of the fine powder discharge port 14a. A groove 51 is provided in the second region 26a of the classification plate 16 facing the first region 24a around the fine powder discharge port 14a. In the air classifier 10b, the first region 24a of the upper disk-shaped portion 14 is the region facing the periphery of the fine powder discharge port 16b. The classification plate 16 does not have a second cylindrical portion 22. The air classifier 10c has a first cylindrical portion 20 in the upper disk-shaped portion 14 (one of the members), and a groove 51 is provided in the classification plate 16 (the other member). The air classifier 10c can achieve the same effects as the air classifier 10 shown in FIG. The grooves 51 prevent the powder from adhering to the inside of the classification chamber 18, allowing stable classification over a long period of time, and therefore the classification accuracy can be maintained over a long period of time. In addition, the first cylindrical portion 20 prevents large particle size coarse powder Pc (see Figure 1) from flowing into the fine powder recovery pipe 30 (see Figure 1), thereby making it possible to reduce the particle size of the recovered fine powder Pf (see Figure 1).

[0040] (5th example of air classifier) FIG. 7 is a schematic partial cross-sectional view showing a fifth example of an air classifier according to an embodiment of the present invention. In the air classifier 10d shown in FIG. 7, the same components as those in the air classifier 10a shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10d shown in Figure 7 differs from the air classifier 10a shown in Figure 4 in that it does not have a first cylindrical portion 20 and that the classification plate 16 does not have a groove portion 51, but otherwise has the same configuration as the air classifier 10a shown in Figure 4. The air current classifier 10d has a second cylindrical portion 22 on the classification plate 16 (the other member), and a groove portion 50 on the upper disk-shaped portion 14 (the one member). The air classifier 10d can achieve the same effects as the air classifier 10 shown in Fig. 1. Furthermore, the grooves 50 prevent powder from adhering to the inside of the classification chamber 18, allowing stable classification over a long period of time, thereby maintaining classification accuracy over a long period of time. Furthermore, the second cylindrical portion 22 prevents the coarse powder Pc having a large particle size from flowing into the fine powder recovery pipe 30 (see FIG. 1), thereby making it possible to further reduce the particle size of the recovered fine powder Pf.

[0041] (Sixth example of an air classifier) FIG. 8 is a schematic partial cross-sectional view showing a sixth example of an air classifier according to an embodiment of the present invention. In the air classifier 10e shown in FIG. 8, the same components as those in the air classifier 10a shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10e shown in Fig. 8 is different from the air classifier 10a shown in Fig. 4 in that the diameter D1 of the first cylindrical portion 20 and the diameter D2 of the second cylindrical portion 22 are different, but otherwise has the same configuration as the air classifier 10a shown in Fig. 4. In the air classifier 10e, the diameter D1 of the first cylindrical portion 20 is larger than the diameter D2 of the second cylindrical portion 22. The air classifier 10e can achieve the same effects as the air classifier 10a shown in FIG.

[0042] (7th example of air classifier) FIG. 9 is a schematic partial cross-sectional view showing a seventh example of an air classifier according to an embodiment of the present invention. In the air classifier 10f shown in FIG. 9, the same components as those in the air classifier 10a shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10f shown in Fig. 9 is different from the air classifier 10a shown in Fig. 4 in that the diameter D1 of the first cylindrical portion 20 and the diameter D2 of the second cylindrical portion 22 are different, but otherwise has the same configuration as the air classifier 10a shown in Fig. 4. In the air classifier 10f shown in Fig. 9, the diameter D2 of the second cylindrical portion 22 is larger than the diameter D1 of the first cylindrical portion 20. The air classifier 10e can achieve the same effects as the air classifier 10a shown in FIG.

[0043] (8th example of air classifier) FIG. 10 is a schematic partial cross-sectional view showing an eighth example of an air classifier according to an embodiment of the present invention. In an air classifier 10g shown in FIG. 10, the same components as those in the air classifier 10a shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10g shown in Figure 10 differs from the air classifier 10a shown in Figure 4 in that an inclined portion 24b is formed in the first region 24a of the upper disk-shaped portion 14 and an inclined portion 26b is formed in the second region 26a of the classification plate 16; otherwise, it has the same configuration as the air classifier 10a shown in Figure 4.

[0044] In an air current classifier 10g shown in Fig. 10, an inclined portion 24b is formed on the surface 14c of the upper disk-shaped portion 14 that faces the classification chamber 18, on the side closer to the cylindrical first cylindrical portion 20. A groove portion 50 is formed in the inclined portion 24b. On the surface 16c of the classification plate 16 facing the classification chamber 18, an inclined portion 26b is formed on the side closer to the cylindrical second cylindrical portion 22. A groove portion 51 is provided in the inclined portion 26b. The inclined portions 24b and 26b are inclined surfaces formed by flat surfaces and have a linear cross-sectional shape. The inclined portions 24b and 26b are inclined so that the height of the classification chamber 18 gradually increases from the annular wall 19 toward the fine powder discharge port 14a. That is, the inclined portion 24b of the upper disk-shaped portion 14 rises toward the fine powder discharge port 14a. The inclined portion 26b of the classification plate 16 falls toward the second cylindrical portion 22.

[0045] By providing the inclined portion 24b and the inclined portion 26b, the length L1 of the first cylindrical portion 20 and the length L2 of the second cylindrical portion 22 can be increased, and the particle size of the recovered fine powder Pf (see Figure 1) can be reduced.

[0046] The angle of the inclined portion 24b of the upper disk-shaped portion 14 relative to a line parallel to the direction W, and the angle of the inclined portion 26b of the classification plate 16 are both represented by θ. The angle θ is preferably 5° to 30°, and more preferably 10° to 20°. If the angle θ is approximately 5° to 30°, the classification points can be made smaller when the raw material powder Ps is classified into fine powder Pf and coarse powder Pc. The angle θ of the inclined portion 24b of the upper disk-shaped portion 14 and the angle θ of the inclined portion 26b of the classification plate 16 may be the same or different. The surface 14c of the upper disk-shaped portion 14 may be configured as a slope extending from the periphery to the outer edge of the first cylindrical portion 20. That is, the surface 14c of the upper disk-shaped portion 14 may be configured as a slope. The surface 16c of the classification plate 16 may be configured as a slope extending from the periphery to the outer edge of the second cylindrical portion 22. That is, the surface 16c of the classification plate 16 may be configured as a slope.

[0047] As described above, the cross-sectional shape of the inclined portions 24b and 26b is linear, but the cross-sectional shape does not have to be linear, and the cross-sectional shape may be curved, with the inclined portions 24b and 26b being configured with curved surfaces so that the height increases from the outside to the center of the classification chamber 18, i.e., the height of the inclined portions 24b and 26b increases at the center of the classification chamber 18. Furthermore, the inclined portions 24b and 26b may be configured with a combination of flat and curved surfaces, in which case the cross-sectional shape will be a combination of straight and curved lines. The airflow classifier 10g is configured to have a first cylindrical portion 20 and a second cylindrical portion 22, but is not limited to this, and it is sufficient if at least one of the first cylindrical portion 20 and the second cylindrical portion 22 is present. Furthermore, in the air current classifier 10g, it is sufficient that at least one of the inclined portion 24b and the inclined portion 26b is present. Furthermore, in the air current classifier 10g, it is sufficient that at least one of the grooves 50 and 51 is present.

[0048] (9th example of air classifier) FIG. 11 is a schematic partial cross-sectional view showing a ninth example of an air classifier according to an embodiment of the present invention. In the air classifier 10h shown in FIG. 11, the same components as those in the air classifier 10b shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10h shown in Figure 11 differs from the air classifier 10b shown in Figure 5 in that an inclined portion 26b is formed in the second region 26a of the classification plate 16, but otherwise has the same configuration as the air classifier 10b shown in Figure 5. In the air classifier 10h shown in Figure 11, the surface 16c of the classification plate 16 facing the classification chamber 18 is formed with an inclined portion 26b. The inclined portion 26b is a slope composed of flat surfaces and has a linear cross-sectional shape. The inclined portion 26b is inclined from the annular wall 19 toward the fine powder discharge port 16b, i.e., from the outside of the classification chamber 18 toward the center, so that the height of the classification chamber 18 decreases. In other words, the surface 16c of the classification plate 16 slopes downward toward the outer end 16a. Grooves 51 are provided in the inclined portion 26b, i.e., the slope. The angle β of the inclined portion 26b of the classification plate 16 with respect to a line parallel to the direction W of the upper disk-shaped portion 14. The angle β is preferably 5° to 30°, and more preferably 10° to 20°. The air classifier 10h can achieve the same effects as the air classifier 10b shown in FIG. In the air current classifier 10h, the inclined portion 26b is provided on the surface 16c of the classification plate 16, but this is not limited thereto, and the inclined portion 24b (see FIG. 10) may be provided on the surface 14c of the upper disk-shaped portion 14. Also, it is sufficient if at least one of the inclined portion 24b and the inclined portion 26b is provided. Furthermore, the airflow classifier 10h is configured to have a first cylindrical portion 20 and a second cylindrical portion 22, but is not limited to this, and it is sufficient if at least one of the first cylindrical portion 20 and the second cylindrical portion 22 is present. In the configuration of the coarse powder recovery section shown in Figure 11, fine powder Pf (not shown) is discharged from the classification plate 16 side, and coarse powder Pc (not shown) is discharged from the gap 39 (coarse powder discharge port 66) on the classification plate 16 side, between the outer end 16a of the classification plate 16 and the annular wall 19 of the casing 12 (see Figure 1).

[0049] (10th example of air classifier) Fig. 12 is a schematic partial cross-sectional view showing a tenth example of an air classifier according to an embodiment of the present invention. In an air classifier 10i shown in Fig. 12, the same components as those in the air classifier 10h shown in Fig. 11 are designated by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10i shown in Figure 12 differs from the air classifier 10h shown in Figure 11 in that it does not have the first cylindrical portion 20, but otherwise has the same configuration as the air classifier 10h shown in Figure 11. In the configuration of the coarse powder recovery section shown in Figure 12, fine powder Pf (not shown) is discharged from the classification plate 16 side, and coarse powder Pc (not shown) is discharged from the gap 39 (coarse powder discharge port 66) on the classification plate 16 side, between the outer end 16a of the classification plate 16 and the annular wall 19 of the casing 12 (see Figure 1). The air classifier 10h can achieve the same effects as the air classifier 10 shown in FIG.

[0050] (11th example of air classifier) FIG. 13 is a schematic cross-sectional view showing an eleventh example of an air classifier according to an embodiment of the present invention. In an air classifier 10j shown in FIG. 13, the same components as those in the air classifier 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. The air classifier 10j shown in Figure 13 differs from the air classifier 10 shown in Figure 1 in that an ejector section 54 is provided in the raw material supply section 40 and that a guide vane 62 is provided instead of the second air nozzle 36, but the rest of the configuration is the same as that of the air classifier 10 shown in Figure 1.

[0051] In the air flow classifier 10j shown in Fig. 13, an ejector unit 54 is provided in the supply pipe 42 of the raw material supply unit 40. The ejector unit 54 has a jet nozzle 55 that jets raw material powder Ps into the classification chamber 18 and a pressure unit 57 that supplies, for example, air at high pressure to the jet nozzle 55. The jet nozzle 55 is connected to, for example, the upper disk-shaped unit 14 by a pipe 56. The high-pressure air supplied from the pressure unit 57 via the jet nozzle 55 and the pipe 56 causes the raw material powder Ps in the raw material supply unit 40 to pass through the opening 42a of the upper disk-shaped unit 14 and be supplied to the classification chamber 18. In the air flow classifier 10j, the ejector section 54 is provided, so that the raw material powder Ps can be reliably supplied to the swirling flow generated in the classification chamber 18. The ejection nozzle 55 and pressure section 57 of the ejector section 54 can be any known device used for transporting powder.

[0052] 13, a plurality of guide vanes 62 are provided along the outer edge of the classification chamber 18, similar to the second air nozzle 36 in the air classifier 10 shown in FIG. 1. The guide vanes 62 are provided on the annular wall 19 below the first air nozzle 34 in the direction H. Like the first air nozzle 34, the guide vanes 62 are arranged at equal intervals in the circumferential direction of the classification chamber 18, each at a predetermined angle relative to the tangent direction of the outer edge of the classification chamber 18. The gas supply unit has the first air nozzle 34 and the guide vanes 62. The gas supply unit may have the guide vanes 62 without the first air nozzle 34. A pushing chamber 64 is provided around the outer periphery of the plurality of guide vanes 62 to store air and supply the gas into the classification chamber 18. The pushing chamber 64 is connected to a pressurized gas supply unit (not shown). Gas at a predetermined pressure is supplied from the pressurized gas supply unit through the pushing chamber 64 and between the plurality of guide vanes 62. By supplying pressurized gas to the first air nozzle 34 and the guide vanes 62, respectively, a swirling flow is generated in the classification chamber 18.

[0053] In the air flow classifier 10j, the raw material powder Ps is centrifuged while swirling and moving downward inside the classification chamber 18. The guide vanes 62 function to adjust the swirling speed of the raw material powder Ps during centrifugation. Each guide vane 62 is rotatably supported on the annular wall 19 by, for example, a rotating shaft (not shown) and is engaged with a rotating plate (not shown) by a pin (not shown). For example, by rotating the rotating plate, all of the guide vanes 62 are simultaneously rotated by a predetermined angle. By rotating the rotating plate and rotating all of the guide vanes 62 by a predetermined angle, the spacing between the guide vanes 62 can be adjusted, thereby changing the flow velocity of gas, e.g., air, passing through the gaps between the guide vanes 62. This allows for changes in classification performance, such as classification point. Furthermore, the provision of the guide vanes 62 allows for a wider selection range of classification points. 13 The air classifier 10j shown in FIG. 1 can also achieve the same effects as the air classifier 10 shown in FIG.

[0054] The air classifier 10j is configured to have the ejector section , but the above-mentioned air classifiers 10, 10a to 10i may also be configured to have the ejector section . Furthermore, the raw material supply unit 40 is configured to be connected to the upper disk-shaped portion 14 and to supply the raw material powder Ps to the swirling flow generated in the classification chamber 18 through the opening 42a of the upper disk-shaped portion 14, but this is not limitative. For example, the raw material supply unit 40 may be connected to the classification plate 16 and the raw material powder Ps may be supplied to the swirling flow generated in the classification chamber 18.

[0055] Furthermore, in the air classifier 10j, the guide vane 62 is provided in place of the second air nozzle 36 of the air classifier 10 shown in Fig. 1, but the present invention is not limited to this. In the air classifiers of the second to eleventh examples of the air classifier described above, the guide vane 62 can also be provided in place of the second air nozzle 36.

[0056] The present invention is basically configured as described above. Although the air classifier of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. [Example]

[0057] Classification by the air classifier of the present invention will be described in more detail below. The raw material powder was classified using the air classifier 10a shown in FIG. 4 and the first air classifier 100 shown in FIG. 14 for comparison. Fig. 14 is a schematic cross-sectional view showing a first air classifier for comparison. In the first air classifier 100 shown in Fig. 14, the same components as those in the air classifier 10a shown in Fig. 4 are given the same reference numerals, and detailed description thereof will be omitted. The first air classifier 100 shown in Figure 14 has the same configuration as the air classifier 10a shown in Figure 4, except that it does not have groove portions 50 and 51, as compared to the air classifier 10a shown in Figure 4.

[0058] Classification was carried out under the same classification conditions, such as the air volume, for the air classifier 10a of the present invention and the first air classifier 100 for comparison. The raw material powder used was ceramic particles with an average particle size of 0.4 μm, measured by laser diffraction and scattering. The results of the classification are shown in the graph of Figure 15. Figure 16 shows the ceramic particles after classification by the air classifier 10a. Figure 17 shows the ceramic particles after classification by the first air classifier 100. Figures 16 and 17 are SEM (Scanning Electron Microscope) images at a magnification of 10,000 times. In FIG. 15, reference numeral 70 indicates the classification results of the air classifier 10a shown in FIG. 4, and reference numeral 72 indicates the classification results of the first air classifier 100 shown in FIG. 14. As shown in FIG. 15, classification accuracy is high, and the present invention can achieve a smaller classification point. As shown in FIGS. 16 and 17, more coarse particles were observed after classification in the first air classifier 100 than in the air classifier 10a. It was also confirmed that more powder adhered to the first cylindrical portion 20 in the first air classifier 100 for comparison than in the air classifier 10a.

[0059] Figure 18 is a schematic partial cross-sectional view showing a second air current classifier for comparison. In the second air current classifier 102 shown in Figure 18, the same components as those in the air current classifier 10g shown in Figure 10 are given the same reference numerals, and detailed description thereof will be omitted. The second air current classifier 102 shown in Figure 18 has the same configuration as the air current classifier 10g shown in Figure 10, except that the second air current classifier 102 shown in Figure 18 does not have the groove portions 50 and 51 provided therein.

[0060] Classification was carried out under the same classification conditions, such as the air volume, for the air classifier 10g of the present invention and the second air classifier 102 for comparison. The raw material powder used was ceramic particles with an average particle size of 0.4 μm, measured by laser diffraction and scattering. The results of the classification are shown in the graph in Figure 19. Figure 20 shows the ceramic particles after classification using the air classifier 10g. Figure 21 shows the ceramic particles after classification using the second air classifier 102. Figures 20 and 21 are SEM images at a magnification of 10,000 times. In FIG. 19, reference numeral 74 indicates the classification results of the air classifier 10g shown in FIG. 10, and reference numeral 76 indicates the classification results of the second air classifier 102 shown in FIG. 18. As shown in FIG. 19, classification accuracy is high, and the present invention can achieve a smaller classification point. As shown in FIGS. 20 and 21, more coarse particles were observed after classification in the second air classifier 102 than in the air classifier 10g. It was also confirmed that more powder adhered to the first cylindrical portion 20 in the second air classifier 102 for comparison than in the air classifier 10g. [Explanation of symbols]

[0061] 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g air classifier 10h, 10i, 10j Airflow classifier 12 Casing 12a surface 13 Ceiling Wall 13b outer edge 14 Upper disc 14a, 16b Fine powder outlet 16 Classification board 16a Outer end 18 Classification room 19 Circular Wall 20 First cylindrical portion 22 Second cylindrical portion 23 Gap 24a The First Region 24b Slope 26a Second Area 26b Slope 28 Coarse powder recovery room 30 Fine powder collection pipe 30c end 34 First air nozzle 36 Second Air Nozzle 38 Third Air Nozzle 39 Gap 40 Raw material supply department 42 Supply pipe 50, 51, 52 Groove 54 Ejector section 55 Spout nozzle 56 Piping 60 Fine powder collection pipe 62 Guide vane 64 Pushing Room 66 Coarse powder outlet 100 First air flow classifier 102 Second air flow classifier H direction Pc coarse powder Pf fine powder Ps raw material powder W direction β, θ angles

Claims

1. a casing having a ceiling wall and an annular wall provided continuously with the outer edge of the ceiling wall; a classification plate disposed on the ceiling wall of the casing with its surface facing the ceiling wall; a classification chamber defined between the ceiling wall of the casing and the surface of the classification plate; a gas supply unit that supplies gas into the classification chamber to generate a swirling flow; a raw material supply unit that supplies raw material powder to the swirling flow generated in the classification chamber; a fine powder discharge port provided in the center of one of the ceiling wall of the casing that configures the classification chamber and the surface of the classification plate; a coarse powder discharge port that opens along an outer periphery of the classification chamber on either the ceiling wall or the surface of the classification plate facing the ceiling wall; An air classifier having a groove portion provided in at least one of the ceiling wall and the surface of the classification plate.

2. a first cylindrical portion provided at the fine powder discharge port; and a second cylindrical portion provided on the surface of the classification plate in the classification chamber, facing the first cylindrical portion and spaced a predetermined gap from the first cylindrical portion.

3. The air classifier according to claim 2 , wherein the first cylindrical portion and the second cylindrical portion have different diameters.

4. a slope is formed on at least one of the ceiling wall of the casing and the surface of the classification plate, The air classifier according to claim 1 , wherein the groove is provided on the inclined surface.

5. a slope is formed on at least one of a periphery of the first cylindrical portion of the ceiling wall of the casing and a periphery of the second cylindrical portion of the surface of the classification plate, The air classifier according to claim 2 or 3, wherein the groove is provided on the inclined surface.

6. 6. The air classifier according to claim 1, wherein the fine powder discharge port is circular, and the groove is provided concentrically with the fine powder discharge port.

7. The air classifier according to any one of claims 1 to 6, wherein the grooves are provided in the ceiling wall and the surface of the classification plate.

8. 8. The air classifier according to claim 7, wherein the fine powder discharge outlet is circular, the groove is provided concentrically with the fine powder discharge outlet, and the groove provided in the ceiling wall faces the groove provided on the surface of the classification plate.

9. The groove is provided concentrically around the fine powder discharge port on the side of the ceiling wall and the surface of the classification plate where the fine powder discharge port is located, and a concentric groove is provided opposite the concentric groove provided in the area around the fine powder discharge port on the side where the fine powder discharge port is not located, 8. The air classifier according to claim 7, wherein the concentric groove provided on the side where the fine powder discharge outlet is located and the concentric groove provided on the side where the fine powder discharge outlet is not located are located at the same position in a direction perpendicular to the direction in which the ceiling wall of the casing of the classification chamber and the surface of the classification plate face each other.

10. The air classifier according to any one of claims 1 to 5, wherein a plurality of the grooves are provided along the periphery of the fine powder discharge port.

11. The air classifier according to claim 2 , wherein the ceiling wall has the first cylindrical portion, and the surface of the classification plate has the groove portion.

12. The air classifier according to claim 2 , wherein the second cylindrical portion is provided on the surface of the classification plate, and the groove portion is provided in the ceiling wall.

13. 6. The air classifier according to claim 4, wherein the inclined surface is inclined so that the height of the classification chamber gradually increases from the outside toward the center of the classification chamber.

14. 6. The air classifier according to claim 4, wherein the inclined surface is inclined so that the height of the classification chamber decreases from the outside toward the center of the classification chamber.

15. The air classifier according to any one of claims 1 to 14, wherein the raw material supply unit is connected to either the ceiling wall of the casing that constitutes the classification chamber or the surface of the classification plate, and supplies the raw material powder to the swirling flow generated in the classification chamber.

16. 16. The air classifier according to claim 1, wherein the raw material supply unit has a jet nozzle that supplies the raw material powder to the swirling flow generated in the classification chamber.

17. The air classifier according to any one of claims 1 to 16, wherein the gas supply unit has a plurality of air nozzles, and the air nozzles are arranged at equal intervals in the circumferential direction of the classification chamber along the outer edge of the classification chamber.

18. The air classifier according to any one of claims 1 to 16, wherein the gas supply section has a plurality of guide vanes, and each guide vane is arranged at equal intervals in the circumferential direction of the classification chamber along the outer edge of the classification chamber.

Images