Classification device and method for classifying powder using same

Abstract

The present invention affords the following configuration in order to provide a classification device capable of classifying powder without damaging a mesh while securing a predetermined throughput, even when classifying highly adhesive powder such as, for example, an electrode material for a lithium-ion battery.　Provided are: a classification device comprising a classification mesh for classifying powder, at least two pressing plates capable of applying pressure by holding the classification mesh and the powder being classified therebetween, and a vibration mechanism for vibrating the pressing plates; and a method for classifying powder using the classification device.

Description

Classification device and powder classification method using the same

[0001] The present invention relates to a classification device for classifying powder and a method for classifying powder using the same.

[0002] A known technology for classifying powder is disclosed in Patent Document 1. Patent Document 1 describes a classifying device that includes a mesh member that is circular in top view and that classifies powder, a spatula that is positioned above the mesh member and rotates via a vertically disposed rotation shaft to press the powder against the mesh member, and a motor that rotates the rotation shaft.

[0003] JP 2022-36864 A

[0004] When attempting to classify highly adhesive powders using the technology described in Patent Document 1, it is necessary to press the spatula against the mesh with a strong force to perform the classification. However, because the spatula is pressed against one side of the mesh member, if the pressing force is strong, the mesh may stretch, widening the openings or even breaking.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a classification device that can classify highly adhesive powders, such as electrode materials for lithium ion batteries, without damaging the mesh and while ensuring a predetermined throughput, and a method for classifying powders using the same.

[0006] To achieve the above object, the present invention provides a classification device including a classification mesh for classifying powder, at least two pressure plates capable of pressing the classification mesh and the powder to be classified so as to sandwich the classification mesh and the powder, and a vibration mechanism for vibrating the pressure plates, and a method for classifying powder using the same.

[0007] According to the present invention, it is possible to provide a classification device that can classify highly adhesive powders without damaging the mesh and while ensuring a predetermined throughput, and a classification method using the same.

[0008] 1 is a cross-sectional view showing a schematic configuration of a classification device according to Example 1. FIG. 2 is a top view showing a schematic configuration of a classification device according to Example 2. FIG. 3 is a cross-sectional view showing the structure of a supply unit 15 according to Example 2. FIG. 4 is a top view showing the opening shape of a mask 29 according to Example 2. FIG. 5 is a cross-sectional view showing the structure of a classification unit 16 according to Example 2. FIG. 6 is a cross-sectional view showing the structure of a mesh cleaning unit 17 according to Example 2. FIG. 7 is a top view showing a classification device according to Example 3. FIG. 8 is a cross-sectional view showing the structure of a classification unit 50 according to Example 3. FIG. 9 is a cross-sectional view showing a schematic configuration of a classification device according to Example 4. FIG. 10 is a bottom view of a base plate 61 according to Example 4. FIG. 11 is a top view of a rotating plate 65 according to Example 4. FIG. 12 is a top view of a base plate 76 according to Example 4.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The examples are illustrative of the present invention, and for clarity of explanation, appropriate omissions and simplifications have been made. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] When there are multiple components with the same or similar functions, they may be described using the same reference numeral with different subscripts. When there is no need to distinguish between these multiple components, the subscripts may be omitted.

[0012] Example 1 will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing a schematic configuration of a classification device according to Example 1. The classification device 1 includes a feeder 2, a classification mesh 3, lifting mechanisms 4 and 11, ultrasonic vibrators 5 and 10, a vibration plate 6, a suction housing 7, aperture plates 8 and 9, a suction nozzle 12, an air injection nozzle 13, and a roller 14.

[0013] The feeder 2 supplies a fixed amount of powder onto the classification mesh 3. The classification mesh 3 is configured in a loop and transports the powder while being circulated by a roller 14. The classification mesh 3 has a mesh size (roughness) that is equal to or smaller than the lower limit of the foreign particle size to be removed and larger than the median particle size of the powder. Here, even if the mesh size of the classification mesh 3 is larger than the foreign particle size, if it is only slightly larger, the foreign particles can be substantially removed and throughput can be improved, but if the mesh size is smaller than the foreign particle size, removal can be more reliable and reliability can be improved. If metal foreign matter originating from the mesh needs to be prevented from being mixed into the powder, a resin mesh such as nylon can be used as the material for the classification mesh 3.

[0014] Two aperture plates 8 and 9 are attached to the suction housing 7. The aperture plates flatten the classification mesh 3 when it is pressed against the powder, allowing the powder that passes through the classification mesh to be sucked in. These highly rigid plates have multiple apertures that penetrate vertically for powder suction. To reduce suction unevenness due to open / closed positions, it is desirable to increase the aperture ratio by making each aperture small and arranging them densely. However, this reduces rigidity and may lead to deformation during pressing. Deformation of the aperture plates causes the classification mesh to deform, changing the mesh opening shape and preventing the expected classification performance. Furthermore, for materials with an average particle size of several microns to several tens of microns, such as electrode materials for lithium-ion batteries, classification meshes with openings of 100 μm or less are often used. However, such meshes are weak and may tear if deformed significantly. Therefore, by installing two aperture plates with different aperture sizes and aperture ratios, both suppression of suction unevenness and rigidity can be achieved. The aperture size of the aperture plate 8 is made smaller than that of the aperture plate 9, and the apertures are arranged at a high density to increase the aperture ratio.

[0015] If it is desired to prevent metallic foreign matter from being mixed into the powder, it is desirable to form the aperture plates 8 and 9 and the suction housing 7 from resin. However, if sufficient rigidity cannot be obtained, they may be formed from a metal such as stainless steel or aluminum. In this case, it is desirable to form a non-metallic layer such as a resin coating such as a fluororesin or a DLC coating in the area that comes into contact with the powder. Furthermore, if sufficient rigidity can be obtained with the aperture plate 8 alone, the aperture plate 9 may be made of a resin mesh such as nylon.

[0016] The suction housing 7 is attached to a lifting mechanism 11, and is brought close to the classification mesh 3 during classification, and is moved away when the classification mesh 3 is fed by rollers.

[0017] It is desirable to use a hard material such as metal for the diaphragm 6 in order to suppress energy attenuation of the ultrasonic vibrator.To prevent contamination of the powder, it is desirable to apply a fluororesin coating, PEEK coating, DLC coating, or an anodized aluminum coating to the surface of the diaphragm 6.

[0018] The ultrasonic vibrator 5 is fixed to a vibration plate 6, which is fixed to a lifting mechanism 4. During classification, the vibration plate 6 is lowered by the lifting mechanism 4, pressing the powder and the classification mesh 3 against the aperture plate 8. High-frequency power is then applied to the ultrasonic vibrator 5, causing it to vibrate. This fluidizes the powder, and particles smaller than the mesh openings of the classification mesh 3 pass through the classification mesh 3. By applying vibration while pressing against the powder, even highly adhesive powder can be broken down into agglomerates and fluidized. By simultaneously applying suction while applying vibration, the powder that has passed through the classification mesh 3 is suction-collected via the suction housing 7. Furthermore, applying vibrations using the ultrasonic vibrator 10 attached to the suction housing 7 at this time further promotes fluidization, increasing the speed at which the powder passes through the classification mesh 3.

[0019] During classification, a control unit (not shown) controls the lifting mechanism 4 to adjust the height of the vibration plate 6 so that it can follow the decrease in the powder layer thickness that occurs as the powder passes through the classification mesh 3. Alternatively, the vibration plate 6 may be made to follow the decrease by an elastic member such as a spring.

[0020] After classification, the remaining powder that did not pass through the classification mesh 3 is sucked and collected by the suction nozzle 12. If the powder is highly adhesive or if the mesh is clogged, suction alone may not be sufficient to remove it, so air is sprayed from below the mesh by the air injection nozzle 13 to ensure that the powder on the mesh is removed.

[0021] As described above, according to this embodiment, by applying vibrations while pressing the vibrating plate and the aperture plate, it is possible to apply vibrations while pressing the powder strongly against the mesh while suppressing deformation and damage to the mesh, thereby improving the classification throughput even for highly adhesive powders. Furthermore, by fixing an ultrasonic vibrator to the vibrating plate, the vibrator is close to the powder, allowing strong vibration energy to be applied to the powder, further improving the classification throughput.

[0022] In this embodiment, an example has been described in which two aperture plates 8 and 9 with different apertures are installed, but if it is possible to achieve both flatness of the classification mesh and suppression of uneven suction, it may be configured with a single aperture plate.

[0023] Example 2 will be described with reference to Figures 2 to 6. Figure 2 is a top view showing the schematic configuration of a classification device in Example 2. In Example 1, the classification mesh was configured in a loop shape, but in Example 2, the classification mesh is fixed to a frame and the frame is transported between each processing section, thereby improving the operability when replacing the mesh. The classification device in Example 2 includes a supply unit 15, a classification unit 16, a mesh cleaning unit 17, a mesh transport mechanism 18, and a mesh frame 23.

[0024] The mesh frame 23 has a classification mesh 25 fixed to a frame 24, and powder is placed on the classification mesh 25 and transported between the treatment sections.

[0025] The classification mesh 25 has an opening size equal to or smaller than the lower limit of the size of foreign particles to be removed, but larger than the median particle size of the powder. Even if the opening size of the classification mesh 25 is slightly larger than the size of the foreign particles, substantial removal of the foreign particles is possible and throughput is improved, but an opening size smaller than the size of the foreign particles allows for more reliable removal and increases reliability. If metal foreign particles originating from the mesh need not be mixed into the powder, it is desirable to use a resin mesh such as nylon as the material for the classification mesh 3.

[0026] The mesh transport mechanism 18 transports the mesh frame 23 between each processing section, and includes a hand 19, a suction pad 20 that sucks the mesh frame 23 by negative pressure or the like, a linear motion mechanism 21, and a rotation mechanism 22. The mesh frame 23 arranged at each processing section is fixed by the suction pad 20, and is transported by the linear motion mechanism 21 to directly above the rotation mechanism 22, after which it is rotated by the rotation mechanism 22 and transported to the next processing section by the linear motion mechanism 21.

[0027] The supply unit 15 is used to set (or place, i.e., temporarily place) the powder to be processed on the mesh frame 23. Fig. 3 is a cross-sectional view showing the structure of the supply unit 15 in Example 2. Fig. 3(a) shows the state when set up, and Fig. 3(b) shows the state when powder is being supplied. The supply unit 15 includes a hopper 26, a feeder 27, a squeegee 28, a mask 29, a support 30, a lifting mechanism 31, a suction pad 32, a base plate 33, and a linear motion mechanism 34.

[0028] The mask 29 is a plate material with an opening 100 in the center, which corresponds to the shape of the powder layer to be supplied onto the mesh frame 23. The mask 29 is made of a plate material such as metal, ceramics, or resin. To prevent contamination of the powder, it is desirable to apply a fluororesin coating, PEEK coating, DLC coating, or, in the case of aluminum, an anodizing treatment to the surface of the mask 29. The mask 29 is fixed to a base plate 33 via supports 30.

[0029] A predetermined amount of powder 35 is stored in the hopper 26. During the setting shown in Figure 3(a), a predetermined amount of powder 35 in the hopper 26 is supplied by the feeder 27 to the space between the squeegee 28 and the mask 29. Meanwhile, the mesh frame 23 is placed on the lifting mechanism 31 by the mesh conveying mechanism 18 and fixed in place by the suction pads 32.

[0030] 3(b), during powder supply, the mesh frame 23 is raised by the lifting mechanism 31 and abuts against the mask 29. Thereafter, the base plate 33 is moved horizontally (toward the right in the drawing) by the linear motion mechanism 34. At this time, the powder 35 supplied between the squeegee 28 and the mask 29 during setting is supplied onto the mesh frame 23. The powder supplied onto the mesh frame 23 is scraped off by the squeegee 28 and spread to the same thickness as the plate thickness of the mask 29. As a result, a powder layer of a size corresponding to the opening 100 of the mask 29 is formed on the mesh frame 23.

[0031] FIG. 4 is a top view showing an example of the opening shape of the mask 29 in Example 2. The simplest configuration of the mask 29 is one with a single rectangular opening. A mask of this shape has the advantage of being able to process a larger amount of powder in a single classification process compared to masks of other shapes. The mask 29 in FIG. 4 has multiple openings 36. This allows multiple powder layers of the same size as the openings 36 to be formed on the mesh frame 23. To suck the powder during classification, an air flow must be created from the outside toward the suction housing. If the powder layer is completely flat, there is no path for air to enter the center of the powder layer, making it impossible to suction. In contrast, in this example, a path for air to flow all the way to the center of the mesh frame 23 can be created, allowing powder to be sucked from the entire surface.

[0032] 5A and 5B are cross-sectional views showing the structure of the classification unit 16 in Example 2. Fig. 5A shows the state at the time of setting, and Fig. 5B shows the state during classification. The classification unit 16 includes ultrasonic vibrators 37 and 43, a vibration plate 38, an elevating mechanism 39, a suction housing 40, and aperture plates 41 and 42.

[0033] Two aperture plates 41 and 42 are attached to the suction housing 40. The aperture plates are designed to flatten the shape of the classification mesh 25 when it is pressed against the powder. They are highly rigid plates with multiple vertically penetrating apertures for powder suction. To reduce suction unevenness due to open / closed positions, it is desirable to increase the aperture ratio by making each aperture small and arranging them densely. However, this reduces rigidity and may lead to deformation during pressing. Deformation of the aperture plates causes the classification mesh to deform, changing the mesh opening shape and preventing the expected classification performance. Furthermore, for materials with an average particle size of several microns to several tens of microns, such as electrode materials for lithium-ion batteries, classification meshes with openings of 100 μm or less are often used. However, such meshes are weak and may tear if deformed significantly. Therefore, by installing two aperture plates with different aperture sizes and aperture ratios, both suppression of suction unevenness and rigidity can be achieved. The aperture size of the aperture plate 42 is made smaller than that of the aperture plate 41, and the apertures are arranged at a high density to increase the aperture ratio.

[0034] If it is desired to prevent metallic foreign matter from being mixed into the powder, it is desirable to form the aperture plates 41 and 42 and the suction housing 40 from resin. However, if sufficient rigidity cannot be obtained, they may be formed from a metal such as stainless steel or aluminum. In this case, it is desirable to form a non-metallic layer, such as a resin coating such as a fluororesin or a DLC coating, on the areas that come into contact with the powder. Furthermore, if sufficient rigidity can be obtained with the aperture plate 42 alone, the aperture plate 41 may be made of a resin mesh such as nylon.

[0035] In this embodiment, an example in which two aperture plates with different apertures are installed has been described, but it may also be configured with a single aperture plate as long as it is possible to achieve both flatness of the classification mesh and suppression of uneven suction.

[0036] During the standby state shown in FIG. 5( a ), the mesh frame 23 carrying the powder 35 is placed on the aperture plate 41 by the mesh transport mechanism 18 (not shown in FIG. 5 ).

[0037] During classification, as shown in FIG. 5( b), the vibration plate 38 is lowered by the lifting mechanism 39, and the classification mesh 25 and powder 35 are pressed against each other by the vibration plate 38 and the aperture plates 41 and 42. High-frequency power is then applied to the ultrasonic vibrator 37, causing it to vibrate. This fluidizes the powder, and particles smaller than the mesh openings of the classification mesh 25 pass through the classification mesh 25. By applying vibration while pressing against the powder, even highly adhesive powder can be broken down into agglomerates and fluidized. By simultaneously applying suction while applying vibration, the powder 35 that has passed through the classification mesh 25 is suction-collected via the suction housing 40. Furthermore, applying vibrations using the ultrasonic vibrator 43 attached to the suction housing 40 further promotes fluidization, increasing the speed at which the powder passes through the classification mesh 25.

[0038] During classification, a control unit (not shown) controls the lifting mechanism 39 to adjust the height of the vibration plate 38 so that it can follow the decrease in the powder layer thickness that occurs as the powder passes through the classification mesh 25. Alternatively, the vibration plate 38 may be made to follow the decrease by an elastic member such as a spring.

[0039] 6 is a cross-sectional view showing the structure of the mesh cleaning unit 17 in Example 2. The mesh cleaning unit 17 includes a suction nozzle 44, an air injection nozzle 45, a support 46, a base plate 48, and a linear motion mechanism 49.

[0040] The mesh frame 23 is fixed to a support 46 by a suction pad 47. The support 46 is fixed to a base plate 48. The base plate 48 is fixed to a linear motion mechanism 49, and can be moved in the horizontal direction.

[0041] Air is sprayed onto the classification mesh 25 by the air spray nozzle 45, and any powder remaining on or clogging the classification mesh 25 is blown upward. The blown powder is sucked and collected by the suction nozzle 44. The mesh frame 23 is moved by the linear motion mechanism 49, so that the entire classification mesh 25 can be cleaned.

[0042] The mesh frame 23 cleaned in the mesh cleaning section 17 is introduced again into the supply section 15 by the mesh transport mechanism 18 (not shown in FIG. 6).

[0043] As described above, according to this embodiment, the classification mesh can be replaced by removing the mesh frame 23 and reattaching the classification mesh offline, which improves the workability of mesh replacement.

[0044] Example 3 will be described with reference to Figure 7. Figure 7 is a top view showing the schematic configuration of a classification device. In Example 3, a vibrating plate is provided in place of the suction housing in the classification unit described in Example 2, and vibration is applied from above and below to improve throughput. Furthermore, a mesh cleaning mechanism is incorporated into the classification unit, thereby making the device more compact. The classification device in Example 3 includes a supply unit 15, a classification unit 50, a mesh conveying mechanism 18, and a mesh frame 23. The supply unit 15, mesh conveying mechanism 18, and mesh frame 23 are the same as those in Example 2, so their description will be omitted.

[0045] 8A and 8B are cross-sectional views showing the structure of the classifying unit 50 in Example 3. Fig. 8A shows the state during setup, Fig. 8B shows the state during classification, and Fig. 8C shows the state during mesh-passed powder collection and mesh cleaning. The classifying unit 50 includes an ultrasonic vibrator 37, vibration plates 38a and 38b, supports 52, a space-forming mesh 53, a lifting mechanism 54, a non-defective product suction nozzle 55, a linear motion mechanism 56, a residual product collection nozzle 57, and an air injection nozzle 58.

[0046] The ultrasonic vibrator 37 is fixed to vibration plates 38a and 38b. The upper vibration plate 38a is fixed to a support 52. The lower vibration plate 38b is fixed to an elevation mechanism 54. A space forming mesh 53 is fixed on the lower vibration plate 38b.

[0047] The space-forming mesh 53 is a thick mesh made of wire with a large wire diameter, and forms a plurality of spaces that accommodate the powder that has passed through the classification mesh 25. The horizontal cross-sectional area of ​​each space in the space-forming mesh 53 is larger than the cross-sectional area of ​​each opening of the classification mesh 25. In other words, the mesh opening of the space-forming mesh 53 is larger than the mesh opening of the classification mesh 25. Furthermore, multiple sheets of the space-forming mesh 53 may be installed in layers depending on the volume of the powder that passes through the classification mesh 25. If it is desired to prevent metal foreign matter originating from the mesh from being mixed into the powder, it is desirable to use a resin mesh such as nylon as the material for the space-forming mesh 53.

[0048] The non-defective product suction nozzle 55 is used to suck and recover the powder that has passed through the classification mesh and accumulated on the space forming mesh 53 after classification, and is moved over the space forming mesh 53 while sucking it by a linear motion mechanism 56 .

[0049] The residual product recovery nozzle 57 and the air injection nozzle 58 are used to remove powder that remains on or clogs the classification mesh 25, and are positioned in the direction in which the mesh frame 23 is transported by the mesh transport mechanism 18 (not shown in Figure 8).

[0050] During the standby state shown in FIG. 8( a ), the mesh frame 23 carrying the powder 35 is placed on the space forming mesh 53 by the mesh transport mechanism 18 .

[0051] During classification as shown in Figure 8(b), the lower vibration plate 38b is raised by the lifting mechanism 54, and the space forming mesh 53, the classification mesh 25, and the powder 35 are pressed against each other by the upper and lower vibration plates 38a, 38b. High-frequency power is then applied to the ultrasonic vibrator 37 to vibrate it. This fluidizes the powder, and particles smaller than the mesh openings of the classification mesh 25 pass through the classification mesh 25. By applying vibrations while pressing against the powder, it is possible to break down agglomerations and fluidize even highly adhesive powder.

[0052] During mesh-passing powder recovery and mesh cleaning shown in Figure 8(c), the non-defective product suction nozzle 55 moves to the right in the figure while suctioning, and suction-recovers the classification mesh-passing powder accumulated in the space-forming mesh 53. The mesh frame 23 is carried out to the right in the figure by the mesh transport mechanism 18. At this time, air is sprayed from the air spray nozzle 58 to blow away any powder remaining on or clogging the classification mesh 25. The blown-away powder is suction-recovered by the residual product recovery nozzle 57.

[0053] As described above, according to this embodiment, the classification throughput can be improved by applying vibration from above and below. Furthermore, by incorporating a mesh cleaning mechanism in the classification section, the device can be made compact.

[0054] Example 4 will be described with reference to Figures 9 to 12. In this example, a mesh conveying mechanism is not used, and a rotating plate-based configuration is used to make the device more compact. Figure 9 is a cross-sectional view showing the schematic configuration of the classification device. As shown in Figure 9, the classification device 1 includes a hopper 59, a feeder 60, base plates 61 and 76, an ultrasonic vibrator 64, a vibration plate 63, lifting mechanisms 62, 75, and 78, a rotating plate 65, a mesh frame 69, a classification mesh 70, a rotation mechanism 71, and a suction housing 72.

[0055] The ultrasonic vibrator 64 is fixed to a vibration plate 63. The vibration plate 63 is fixed to an elevation mechanism 62. The elevation mechanism 62 is fixed to a base plate 61. The base plate 61 is fixed by a support 79.

[0056] 10 is a view of the base plate 61 as viewed from below. The base plate 61 includes a supply port 81, a squeegee plate 80, a suction nozzle 82, and a wall 68. The rotating plate 65 is fixed to a rotation mechanism 71 and rotates in the horizontal direction. The rotation mechanism 71 is fixed to a base plate 76.

[0057] FIG. 11 is a top view of the rotating plate 65. The rotating plate 65 includes an inner plate 66 and a wall 67. The mesh frame 69 is sandwiched and fixed between the rotating plate 65 and the inner plate 66. The classification mesh 70 is fixed to the mesh frame 69. The mesh size of the classification mesh 70 is equal to or smaller than the lower limit of the size of the foreign particles to be removed, but larger than the median particle size of the powder. Even if the mesh size of the classification mesh 70 is slightly larger than the size of the foreign particles, substantial removal of the foreign particles is possible and throughput is improved. However, a mesh size smaller than the size of the foreign particles allows for more reliable removal and increases reliability. If metal foreign particles are to be prevented from being mixed into the powder, it is desirable to use a resin mesh such as nylon as the material for the classification mesh 70.

[0058] 12 is a top view of the base plate 76. The base plate 76 includes a wall 77 and an air injection nozzle 84. The base plate 76 is fixed to an elevating mechanism 78. The suction housing 72 is fixed to an elevating mechanism 75, which is fixed to the base plate 76.

[0059] Two aperture plates 73 and 74 are fixed to the upper opening of the suction housing 72 (aperture plate 74 is hidden under aperture plate 73 in Figure 12). The aperture plates are designed to flatten the mesh shape when pressing the powder against the classification mesh 70. They are highly rigid plates with multiple apertures that penetrate vertically for powder absorption. To reduce suction unevenness due to open / closed positions, it is desirable to increase the aperture ratio by making each aperture small and arranging them densely. However, this reduces rigidity and may lead to deformation during pressing. Deformation of the aperture plates causes deformation of the classification mesh, changing the mesh opening shape and preventing the expected classification performance. Furthermore, for materials with an average particle size of several microns to several tens of microns, such as electrode materials for lithium-ion batteries, classification meshes with openings of 100 μm or less are often used. However, such meshes are weak and may tear if deformed significantly. Therefore, by installing two aperture plates with different aperture sizes and aperture ratios, both suppression of suction unevenness and rigidity can be achieved. The aperture size of the aperture plate 73 is made smaller than that of the aperture plate 74, and the apertures are arranged at a high density to increase the aperture ratio.

[0060] If it is desired to prevent metallic foreign matter from being mixed into the powder, it is desirable to form the aperture plates 73 and 74 and the suction housing 72 from resin. However, if sufficient rigidity cannot be obtained, they may be formed from a metal such as stainless steel or aluminum. In this case, it is desirable to form a non-metallic layer, such as a resin coating such as a fluororesin or a DLC coating, on the areas that come into contact with the powder. Furthermore, if sufficient rigidity can be obtained with the aperture plate 74 alone, the aperture plate 73 may be made of a resin mesh such as nylon.

[0061] The operation of this device will be described below. First, powder is charged into the hopper 59. The rotation angle of the rotary plate 65 is set so that the classification mesh 70 is positioned below the supply port 81, and a predetermined amount of powder is supplied onto the classification mesh 70 by the feeder 60. The powder is stored in the space formed by the classification mesh 70, the squeegee plate 80, and the wall 67.

[0062] Thereafter, when the rotating plate 65 is rotated, the powder on the classification mesh 70 is scraped and spread by the squeegee plate 80, and a powder layer having the same thickness as the thickness of the inner plate 66 is formed on the classification mesh 70. The rotating plate 65 is rotated until the classification mesh 70 is above the suction housing 72.

[0063] The vibration plate 63 is then lowered by the lifting mechanism 62, and the lifting mechanism 75 is further raised by the suction housing 72, sandwiching and pressing the powder and the classification mesh 70 between the vibration plate 63 and the aperture plate 73. Then, while suction is being applied to the suction housing 72, vibration is applied by the ultrasonic vibrator 64, and classification is performed. This fluidizes the powder, and particles smaller than the mesh openings of the classification mesh 70 pass through the classification mesh 70. By applying vibration while pressing against the powder, even highly adhesive powder can be broken down and fluidized. By simultaneously applying suction while applying vibration, the powder that has passed through the classification mesh 70 is suctioned and collected via the suction housing 72. Furthermore, applying vibration by the ultrasonic vibrator 83 attached to the suction housing 72 at this time further promotes fluidization, increasing the speed at which the powder passes through the classification mesh 70.

[0064] During classification, a control unit (not shown) controls the lifting mechanism 62 to adjust the height of the vibration plate 63 so that the vibration plate 63 can follow the decrease in powder layer thickness that occurs as the powder passes through the classification mesh 70. Alternatively, the vibration plate 63 may be made to follow the decrease by an elastic member such as a spring.

[0065] After classification is complete, the vibration plate 63 is raised by the lifting mechanism 62, the suction housing 72 is lowered by the lifting mechanism 75, and then the rotating plate 65 is rotated. At this time, air is sprayed from the air spray nozzle 84 (see FIG. 12) to blow away any powder remaining on or clogging the classification mesh 70. The blown-away powder is sucked and collected by the suction nozzle 82 (see FIG. 10).

[0066] As described above, according to this embodiment, a compact device configuration can be achieved without using a conveying mechanism. In addition, the inside of the powder processing area is almost completely closed off from the outside of the device by the walls 67, 68, and 77, which has the advantage of reducing the risk of contamination from outside the device.

[0067] 1...classification device, 2...feeder, 3, 25...classification mesh, 5, 10...ultrasonic vibrator, 6...vibration plate, 7, 40...suction housing, 8, 9, 41, 42...opening plate, 12...suction nozzle, 13...air injection nozzle, 14...roller, 15...supply section, 16, 50...classification section, 17...mesh cleaning section, 18...mesh conveying mechanism, 23...mesh frame, 29...mask, 53...space forming mesh, 65...rotary plate

Claims

1. A classification device comprising: a classification mesh for classifying powder; at least two pressure plates capable of pressing the classification mesh and the powder to be classified in a sandwiched manner; and a vibration mechanism for vibrating the pressure plates.

2. A classification device according to claim 1, wherein at least one of said pressure plates has an opening and is provided with a suction mechanism for sucking the powder classified by said classification mesh through said opening.

3. A classification device as described in claim 2, characterized in that it has a suction position for sucking in powder classified by the suction mechanism, and a recovery position for recovering powder not sucked in by the suction mechanism, and is provided with a transport mechanism for transporting the classification mesh between the suction position and the recovery position.

4. A classification device as described in claim 3, characterized in that the transport mechanism comprises a rotating disk having the classification mesh fixed to an opening thereof, and transports the classification mesh between the suction position and the recovery position by rotating the rotating disk.

5. A classifying device according to claim 3, characterized in that the classification mesh is provided on at least a part of a looped belt, and the conveying mechanism is a mechanism for rotating the belt with rollers.

6. A classification device according to claim 3, further comprising a holding member for holding said classification mesh, and said transport mechanism is a mechanism for transporting said holding member.

7. A classification device according to claim 3, characterized in that the transport path of said transport mechanism has a cleaning position for cleaning said classification mesh.

8. A classification device according to claim 1, further comprising a mechanism for dividing the powder into a plurality of blocks and placing the blocks on the classification mesh.

9. A method for classifying powder, comprising using the classification device according to any one of claims 1 to 8.

10. A method for classifying powder, comprising: a powder supplying step of supplying powder to a classification mesh that classifies the powder; a powder pressing step of pressing the supplied powder and the classification mesh with at least two pressing plates so as to sandwich them; and a powder vibration step of vibrating the powder and the classification mesh.

11. A method for classifying powder according to claim 10, further comprising a powder suction step of suctioning the powder classified by the powder vibration step.

12. A method for classifying powder according to claim 11, further comprising a powder recovery step of recovering powder that has not been classified by the powder vibration step.

13. A method for classifying powder as described in claim 12, characterized in that the powder suction step and the powder recovery step are each performed at a different position, and the method includes a classification mesh transport step of transporting the classification mesh between the different positions.

14. A method for classifying powder according to any one of claims 10 to 13, comprising: a cleaning step of cleaning the classification mesh.

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