CLASSIFIER AND CLASSIFYING METHOD

Classification device (1) includes casing (2), rotating body (3), blade (4), drive unit (7), control unit (8), tubular member (9), and bypass flow path forming member (11). Casing (2) includes tubular portion (20). Rotating body (3) is disposed inside tubular portion (20), and blade (4) rotates together with rotating body (3). Drive unit (7) rotationally drives rotating body (3). Control unit (8) controls drive unit (7). Tubular portion (20) includes gas inflow port (21), gas outflow port (22), and particle discharge port (23). Tubular member (9) includes internal space (90) communicating with gas inflow port (21) and powder inlet port (93) through which powder is introduced. Bypass flow path forming member (11) includes bypass flow path (110) communicating with gas inflow port (21) and gas outflow port (22). Control unit (8) controls a rotation speed of rotating body (3) to change a classification diameter of a particle to be discharged from particle discharge port (23).

TECHNICAL FIELD

The present disclosure relates to a classification device and a classification method, and more particularly to a classification device and a classification method that classifies particles of powder using a flow of gas.

BACKGROUND ART

Conventionally, as a classification mechanism, a classification mechanism and a classification method for separating fine powder and coarse powder using a swirling flow caused by rotation of a classification rotor to obtain a product having a predetermined particle size range are known (PTL 1).

The classification mechanism disclosed in PTL 1 includes a body casing, a classification rotor provided inside the body casing, a single rotating shaft on which the classification rotor is mounted, and a single drive source for rotationally driving the single rotating shaft.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

In the classification device, improvement of classification efficiency is desired.

An object of the present disclosure is to provide a classification device and a classification method capable of improving classification efficiency.

A classification device according to an aspect of the present disclosure includes a casing, a rotating body, a blade, a drive unit, and a control unit. The casing includes a tubular portion. The rotating body is disposed inside the tubular portion and is rotatable about a rotation axis along an axial direction of the tubular portion. The blade is disposed between the tubular portion and the rotating body, and rotates together with the rotating body. The drive unit rotationally drives the rotating body. The control unit controls the drive unit. The tubular portion includes a gas inflow port, a gas outflow port that is separated from the gas inflow port in the axial direction and allows an inside and an outside of the tubular portion to communicate with each other, and a particle discharge port. The classification device further includes a tubular member and a bypass flow path forming member. The tubular member includes an internal space communicating with the gas inflow port. The tubular member includes a powder inlet port through which powder having a particle size distribution is introduced. The bypass flow path forming member includes a bypass flow path communicating with the gas inflow port and the gas outflow port. The control unit controls a rotation speed of the rotating body by controlling the drive unit to change a classification diameter of a particle to be discharged from the particle discharge port.

A classification method according to another aspect of the present disclosure classifies powder using a classification device. The classification device includes a casing, a rotating body, and a blade. The casing includes a tubular portion having a circular inner peripheral shape. The rotating body is disposed inside the tubular portion and is rotatable about a rotation axis along an axial direction of the tubular portion. The blade is disposed between the tubular portion and the rotating body, and rotates together with the rotating body. The classification method includes a first step and a second step. In the first step, the rotating body is rotated at a first rotation speed to classify particles having a first classification diameter or more from the powder. In the second step, the rotating body is rotated at a second rotation speed higher than the first rotation speed after the first step, and particles having a second classification diameter or more smaller than the first classification diameter are classified from the powder from which particles having the first classification diameter or more have been separated in the first step.

The classification device and the classification method of the present disclosure can improve the classification efficiency.

DESCRIPTION OF EMBODIMENT

FIGS.1to5described in the following exemplary embodiments and the like is a schematic view, and the ratio of the size and the thickness of each component in the drawing does not necessarily reflect the actual dimensional ratio.

First Exemplary Embodiment

Hereinafter, classification device1according to the first exemplary embodiment will be described with reference toFIGS.1to5.FIG.1is a configuration diagram of classification device1according to a first exemplary embodiment.FIG.1is a perspective view of classification device1.FIG.3is a cross-sectional view including rotation axis30in classification device1.FIG.4is a cross-sectional view orthogonal to rotation axis30in classification device1.FIG.5is a schematic diagram when first collection container140and second collection container150are connected to classification device1according to the first exemplary embodiment.

Classification device1classifies powder. The powder has a particle size distribution. In the powder, all the particles do not have a uniform size, and for example, particles having different sizes exist in different proportions within a range from a minimum particle size to a maximum particle size.

In classification device1, a part of a flow path from gas inflow port21to gas outflow port22is formed between casing2and rotating body3. Particle discharge port23is a hole for discharging particles having a relatively large particle size among particles contained in the powder to the outside of casing2.

Classification device1can cause the air flowing into gas inflow port21of tubular portion20of casing2to flow toward gas outflow port22while rotating spirally around rotating body3. In classification device1, the air flowing into a flow path from gas inflow port21of casing2can be moved while being spirally rotated around rotating body3to flow into gas outflow port22. In classification device1, particles having a relatively large particle size among particles of powder conveyed by the airflow flowing into casing2are discharged from particle discharge port23to the outside of casing2while passing through the flow path.FIG.1schematically illustrates particles having a relatively large particle size among particles contained in a powder as first particles P1and particles having a relatively small particle size as second particles P2.

A material of casing2is, for example, metal, but is not limited thereto, and may be resin (for example, ABS resin). Furthermore, casing2may include a metal portion formed of metal and a resin portion formed of resin.

Casing2includes tubular portion20having a circular inner peripheral shape. “Having a circular inner peripheral shape” means that the shape along an inner periphery of the tubular portion20is a circular shape. The shape in a direction along an outer periphery of the tubular portion20is a circular shape. Tubular portion20includes first end201and second end202in axial direction D1of tubular portion20. Casing2includes tubular portion20and bottom24that closes an opening of second end202of tubular portion20. That is, in classification device1according to the first exemplary embodiment, casing2has a bottomed tubular shape. In tubular portion20, the opening of first end201of tubular portion20forms gas inflow port21. Therefore, gas inflow port21penetrates tubular portion20in axial direction D1.

In tubular portion20, an outer diameter of first end201is smaller than an outer diameter of portion203(Hereinafter, also referred to as cylinder203.) surrounding rotating body3in tubular portion20. In axial direction D1of tubular portion20, a length of cylinder203is longer than a length of rotating body3. An inner diameter and an outer diameter of cylinder203are, for example, constant over the entire length of tubular portion20in axial direction D1, but are not limited thereto. For example, the inner diameter and the outer diameter of cylinder203may gradually decrease as it goes away from second end202of tubular portion20. Furthermore, tubular portion20includes portion204(Hereinafter, also referred to as enlarged diameter portion204.) between first end201and cylinder203. An inner diameter and an outer diameter of enlarged diameter portion204gradually increase away from first end201. The outer diameter of enlarged diameter portion204is smaller than the inner diameter of the cylinder203. In enlarged diameter portion204, an opening area gradually increases away from gas inflow port21in axial direction D1of tubular portion20.

In tubular portion20, gas outflow port22is separated from gas inflow port21in axial direction D1of tubular portion20, and allows the inside and outside of tubular portion20communicate with each other between first end201and second end202of tubular portion20. Gas outflow port22is formed along one direction intersecting axial direction D1of tubular portion20near bottom24of casing2. In other words, gas outflow port22is opened to the side of tubular portion20.

In tubular portion20, particle discharge port23is separated from gas inflow port21in axial direction D1of tubular portion20, and allows the inside and outside of tubular portion20to communicate with each other between first end201and second end202of tubular portion20. Particle discharge port23is formed along one direction intersecting axial direction D1of tubular portion20near bottom24of casing2. In other words, particle discharge port23is opened to the side of tubular portion20. Tubular portion20includes a plurality of (for example, two) particle discharge ports23. Two particle discharge ports23are separated in a direction along an outer periphery of tubular portion20. Two particle discharge ports23are aligned in one radial direction of tubular portion20as viewed in axial direction D1of tubular portion20.

In classification device1, an opening width of each of the plurality of particle discharge ports23is shorter than an opening width of gas outflow port22in a direction along an outer periphery of tubular portion20.

Rotating body3is disposed inside tubular portion20and is rotatable about rotation axis30along axial direction D1of tubular portion20. Rotating body3is coupled to a rotating shaft (shaft) of a motor included in drive unit7via shaft71, for example. Shaft71has a round rod shape. A material of shaft71is, for example, stainless steel. Drive unit7is fixed to casing2, for example. Shaft71is disposed such that its axis coincides with rotation axis30of rotating body3.

Rotating body3is disposed coaxially with tubular portion20inside tubular portion20. The phrase “disposed coaxially with tubular portion20” means that rotating body3is disposed so as to align rotation axis30of rotating body3with central axis29(seeFIG.3) of tubular portion20. Rotating body3has, for example, a columnar shape, but is not limited thereto. For example, rotating body3may have a bottomed tubular shape having a bottom wall on a side of gas inflow port21, or may have a truncated cone shape whose outer diameter gradually increases as it goes away from gas inflow port21in axial direction D1of tubular portion20. In a case where rotating body3has a bottomed tubular shape, it is preferable that rotating body3includes a reinforcing wall on an inner side. A material of rotating body3is, for example, ABS resin or polycarbonate resin.

Rotating body3includes first end31on a side of gas inflow port21and second end32on a side of gas outflow port22. Rotating body3is disposed near enlarged diameter portion204between enlarged diameter portion204and bottom24in axial direction D1of tubular portion20. More specifically, in axial direction D1of tubular portion20, a distance between rotating body3and enlarged diameter portion204is shorter than a distance between rotating body3and bottom24.

Blade4is disposed between tubular portion20and rotating body3, and rotates together with rotating body3. In classification device1, a plurality of (here, 24 sheets) blades4is disposed between tubular portion20and rotating body3. That is, classification device1includes the plurality of blades4. The plurality of blades4are connected to rotating body3and separated from inner peripheral surface26of tubular portion20. The plurality of blades4rotate together with rotating body3.

The plurality of blades4are provided on rotating body3over the entire length of rotating body3in a direction along axial direction D1of tubular portion20. That is, the plurality of blades4are provided from first end31to second end32of rotating body3. A material of the plurality of blades4is, for example, ABS resin or polycarbonate resin. In classification device1, the material of the rotating body3and the material of the plurality of blades4are the same, but the present invention is not limited thereto, and they may be different. The plurality of blades4may be formed integrally with rotating body3, or may be formed as a separate member from rotating body3and connected to rotating body3by being fixed to rotating body3.

Each of the plurality of blades4is disposed such that a gap is formed between each blade4and tubular portion20as viewed in axial direction D1of tubular portion20.

In other words, in classification device1, there is a gap between each of the plurality of blades4and inner peripheral surface26of tubular portion20. In a radial direction of rotating body3, a distance between each protruding tip of the plurality of blades4and outer peripheral surface36of rotating body3is shorter than a distance between outer peripheral surface36of rotating body3and inner peripheral surface26of tubular portion20.

Each of the plurality of blades4is disposed in parallel with rotation axis30of rotating body3in a space (flow path) between outer peripheral surface36of rotating body3and inner peripheral surface26of tubular portion20. Each of the plurality of blades4has a flat plate shape. Each of the plurality of blades4has a quadrangular shape that is long in a direction along rotation axis30of rotating body3as viewed in a thickness direction. Each of the plurality of blades4is inclined by a predetermined angle (for example, 45 degrees) with respect to one radial direction of rotating body3when viewed from a side of bottom24in a direction along axial direction D1of tubular portion20. In each of the plurality of blades4, a distal end on a side of tubular portion20in the protruding direction from rotating body3is located behind a proximal end on a side of rotating body3in rotation direction R1of rotating body3(SeeFIG.4.). That is, in classification device1, each of the plurality of blades4is inclined by a predetermined angle (for example, 45 degrees) in rotation direction R1of rotating body3with respect to one radial direction of rotating body3. The predetermined angle is not limited to 45 degrees, and may be an angle larger than 0 degrees and 90 degrees or less. For example, the predetermined angle may be an angle within a range of 10 degrees or more and 80 degrees or less. Each of the plurality of blades4is not limited to the case of being inclined by a predetermined angle in rotation direction R11of rotating body3with respect to one radial direction of rotating body3, and for example, the angle formed with the one radial direction of rotating body3may be 0 degrees. That is, the plurality of blades4may extend radially from rotating body3. As illustrated inFIG.4, the plurality of blades4are arranged at equal angular intervals in a direction along an outer periphery of rotating body3. The “equal angular intervals” mentioned herein are not limited to strictly the same angular intervals, and may be, for example, angular intervals within a predetermined error range (for example, +10% of a prescribed angular interval) with respect to a prescribed angular interval.

In axial direction D1of tubular portion20, a length of each of the plurality of blades4is the same as a length of rotating body3. The length of each of the plurality of blades4is not limited to the same length as rotating body3, and may be longer or shorter than rotating body3.

In axial direction D1of tubular portion20, the length of each of the plurality of blades4is shorter than a length of cylinder203.

Each of the plurality of blades4includes first end41on the side of gas inflow port21and second end42on the side of gas outflow port22and particle discharge port23in axial direction D1of tubular portion20.

Casing2includes space25on the side of particle discharge port23with respect to second end42of each blade4in axial direction D1of tubular portion20. In classification device1, particle discharge port23is located at a position overlapping space25in a direction orthogonal to rotation axis30. That is, particle discharge port23is at a position overlapping space25in a direction orthogonal to axial direction D1of tubular portion20. Furthermore, in classification device1, particle discharge port23is located at a position not overlapping with each blade4in the direction orthogonal to rotation axis30. That is, particle discharge port23is at a position not overlapping each blade4in the direction orthogonal to axial direction D1of tubular portion20. In other words, there is no blade4in a projection region of particle discharge port23when tubular portion20is viewed from the side.

Drive unit7includes, for example, a motor that rotationally drives rotating body3. Although drive unit7couples a rotation shaft of the motor to rotating body3via shaft71, the present invention is not limited thereto, and the rotation shaft of the motor may be directly coupled to rotating body3. Furthermore, drive unit7may be configured to transmit the rotation of the rotating shaft of the motor to rotating body3via a pulley and a rotating belt. The motor may be disposed inside casing2or may be disposed outside casing2. A rotation speed of rotating body3rotationally driven by drive unit7is, for example, 1500 rpm to 3000 rpm.

Control unit8controls drive unit7. Control unit8controls the rotation speed of rotating body3by controlling drive unit7to change a classification diameter of a particle to be discharged from particle discharge port23.

Control unit8includes a computer system. The computer system mainly includes a processor and a memory as hardware. A processor executes a program recorded in a memory of the computer system, thereby implementing a function as control unit8. The program may be recorded in advance in the memory of the computer system, may be provided through a telecommunication line, or may be provided by being recorded in a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive readable by the computer system. The processor of the computer system includes one or a plurality of electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated (LSI) circuit. The integrated circuit such as an IC or an LSI mentioned here is called differently depending on a degree of integration, and includes integrated circuits called a system LSI, a very large scale integration (VLSI), or an ultra large scale integration (ULSI). Moreover, a field-programmable gate array (FPGA) programmed after manufacture of LSI, and a logical device capable of reconfiguring a joint relationship in LSI or reconfiguring circuit partitions in LSI can also be used as processors. The plurality of electronic circuits may be aggregated in one chip or may be provided in a distributed manner on a plurality of chips. The plurality of chips may be aggregated in one device or may be provided in a distributed manner in a plurality of devices. The computer system mentioned here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller also includes one or a plurality of electronic circuits including a semiconductor integrated circuit or a large scale integration.

Classification device1includes particle discharge tubular portion5as described above. Particle discharge tubular portion5is connected to a peripheral edge of particle discharge port23on an outer peripheral surface27of tubular portion20, for example. Particle discharge tubular portion5is a member for discharging first particles P1having a relatively large particle size among the particles contained in the powder. Particle discharge tubular portion5includes internal space50communicating with particle discharge port23and protrudes from outer peripheral surface27of tubular portion20. Particle discharge tubular portion5has a rectangular tubular shape. Furthermore, a part of particle discharge tubular portion5extends from inner peripheral surface26of tubular portion20to the inside of tubular portion20. In particle discharge tubular portion5, with respect to the portion protruding from outer peripheral surface27of tubular portion20, an opening on a side opposite to a side of particle discharge port23has a rectangular shape with a direction along axial direction D1of tubular portion20as a longitudinal direction.

Furthermore, in particle discharge tubular portion5, with respect to the portion extending from inner peripheral surface26of tubular portion20, the opening on the side opposite to the side of particle discharge port23has a rectangular shape with the direction along axial direction D1of tubular portion20as the longitudinal direction.

In classification device1, as illustrated inFIG.4, an inner peripheral surface of particle discharge port23in tubular portion20includes rear inner surface231located on a rear side and front inner surface232located on a front side in a direction along rotation direction R1of rotating body3. Rear inner surface231is formed along one tangential direction of inner peripheral surface26of tubular portion20as viewed in axial direction D1of tubular portion20. Particle discharge tubular portion5protrudes in a direction along the one tangential direction as viewed in axial direction D1of tubular portion20. Particle discharge tubular portion5is at a position not overlapping with blade4in a direction orthogonal to rotation axis30. Part53of particle discharge tubular portion5extends from inner peripheral surface26of tubular portion20along front inner surface232of particle discharge port23to one center line B1(seeFIG.4) of tubular portion20. The one center line B1is orthogonal to rotation axis30of rotating body3and is orthogonal to an axial direction of particle discharge tubular portion5. Classification device1includes a plurality of (for example, two) particle discharge tubular portions5. The plurality of particle discharge tubular portions5are disposed so as to have rotational symmetry as viewed in axial direction D1of tubular portion20.

As illustrated inFIG.5, classification device1may further include first collection container140into which the particles discharged through particle discharge port23and particle discharge tubular portion5enter. As a result, classification device1can collect first particles P1having a relatively large particle size in the powder in first collection container140.

Furthermore, classification device1includes outflow tubular portion6as described above. Outflow tubular portion6is connected to a peripheral edge of gas outflow port22on outer peripheral surface27of tubular portion20, for example. Outflow tubular portion6is a member for allowing the gas from which first particles P1are separated to flow out of casing2. Outflow tubular portion6includes internal space60communicating with gas outflow port22and protrudes from outer peripheral surface27of tubular portion20. Outflow tubular portion6has a rectangular tubular shape. Outflow tubular portion6includes inlet61on the side of gas outflow port22, an outlet62on a side opposite to the side of gas outflow port22, and opening63that allows internal space60of outflow tubular portion6and bypass flow path110of bypass flow path forming member11to communicate with each other. Opening63is separated from inlet61and outlet62between inlet61and outlet62, and allows an inside and an outside of outflow tubular portion6to communicate with each other.

In classification device1, outflow tubular portion6is adjacent to one of two particle discharge tubular portions5. Outflow tubular portion6is located in front of adjacent particle discharge tubular portion5in a direction along rotation direction R1of rotating body3.

In classification device1, outflow tubular portion6is disposed in parallel with adjacent particle discharge tubular portion5as viewed in axial direction D1of tubular portion20, but the present invention is not limited thereto, and for example, outflow tubular portion6may protrude in a direction along one tangential direction of inner peripheral surface26of tubular portion20.

Furthermore, as illustrated inFIG.5, classification device1may further include second collection container150into which the particles flowing out through gas outflow port22and outflow tubular portion6enter. As a result, classification device1can collect second particles P2having a relatively small particle size in the powder in second collection container150.

Classification device1includes tubular member9as described above. Tubular member9includes internal space90communicating with gas inflow port21. Tubular member9includes powder inlet port93through which powder is introduced. Tubular member9includes first end91connected to first end201of casing2and second end92on a side opposite to first end91. Powder inlet port93is formed at a position away from first end91and second end92between first end91and second end92in tubular member9. Classification device1further includes powder inlet tubular portion10. Powder inlet tubular portion10includes an internal space communicating with powder inlet port93and is connected to tubular member9. Powder inlet tubular portion10is connected to a peripheral edge of powder inlet port93on an outer peripheral surface of tubular member9, for example. Powder inlet tubular portion10may be, for example, a hopper. Classification device1further includes blocking unit160capable of opening and closing powder inlet port93. Blocking unit160is a valve. Accordingly, powder inlet port93can be closed by the blocking unit except when the powder is introduced. The blocking unit is controlled by control unit8, for example. The blocking unit may be a manually operated door.

Furthermore, tubular member9includes opening94that allows internal space90of tubular member9and bypass flow path110of bypass flow path forming member11to communicate with each other. Opening94allows the inside and the outside of the tubular member9to communicate with each other at a position away from first end91and powder inlet port93between first end91of tubular member9and powder inlet port93.

Bypass flow path forming member11is, for example, a duct. Bypass flow path forming member11includes first end111on the side of gas outflow port22and second end112on the side of gas inflow port21. First end111of bypass flow path forming member11is connected to a peripheral edge of opening63of outflow tubular portion6. Second end112of bypass flow path forming member11is connected to a peripheral edge of opening94of tubular member9. As a result, classification device1can generate an airflow passing through gas inflow port21, gas outflow port22, and bypass flow path110of casing2.

Furthermore, classification device1further includes switching unit12. Switching unit12switches between a first state in which bypass flow path110is used and a second state in which bypass flow path110is not used in classification device1. Switching unit12switches between a first flow path passing through bypass flow path110and a second flow path not passing through bypass flow path110as a flow path of the gas flowing out from gas outflow port22of casing2. Switching unit12is controlled by control unit8, for example, to switch between the first flow path and the second flow path. Switching unit12includes, for example, opening and closing body121. Opening and closing body121is disposed, for example, in outflow tubular portion6. Opening and closing body121is rotatable between a first position (a position of opening and closing body121indicated by a solid line inFIG.1) where opening63is not covered and internal space60of outflow tubular portion6is partitioned into a space on a side of outlet62of outflow tubular portion6and spaces on a side of inlet61and a side of opening63, and a second position (a position of opening and closing body121indicated by a two-dot chain line inFIG.1) where opening63of outflow tubular portion6is covered and outlet62of outflow tubular portion6communicates with gas outflow port22. InFIG.1, rotation direction R2of opening and closing body121is indicated by an arrow.

Furthermore, classification device1further includes flow rate adjustment unit13. Flow rate adjustment unit13adjusts a flow rate of the gas passing through gas inflow port21, for example. For example, flow rate adjustment unit13is disposed closer to first end91of tubular member9than powder inlet port93in internal space90of tubular member9. For example, flow rate adjustment unit13is controlled by control unit8to adjust the flow rate of the gas passing through gas inflow port21when rotating body3and blades4are rotating. In classification device1, for example, control unit8controls flow rate adjustment unit13so that the flow rate of gas inflow port21becomes substantially constant even when the rotation speed of rotating body3is changed. As a result, classification device1can suppress a decrease in classification efficiency due to an increase in a flow velocity caused by an increase in the flow rate of gas inflow port21when the rotation speed of rotating body3is relatively increased. Flow rate adjustment unit13includes, for example, a valve. The valve is a butterfly valve, but is not limited thereto, and may be, for example, a ball valve. In classification device1, since flow rate adjustment unit13is disposed closer to first end91of tubular member9than powder inlet port93in internal space90of tubular member9, it is possible to suppress the powder particles from colliding with flow rate adjustment unit13.

Furthermore, classification device1further includes air filter14disposed in tubular member9at first end91of tubular member9. Air filter14is a filter for removing foreign substances (for example, dust, dirt, particles, and the like) contained in external air sucked from an opening of first end91of tubular member9when rotating body3and blades4are rotated in classification device1. Note that, inFIG.1, an external air flow is schematically illustrated by trimming arrow F1.

(3) Operation of Classification Device

In classification device1according to the first exemplary embodiment, rotation direction R1(seeFIG.4) of rotating body3is, for example, a clockwise direction when rotating body3is viewed from a side of bottom24of casing2in axial direction D1of tubular portion20. Classification device1rotationally drives rotating body3by drive unit7.

In classification device1, when rotating body3rotates, the plurality of blades4rotate together with rotating body3, and the speed vector of the air flowing through the inner space of casing2has a speed component in a direction parallel to rotation axis30and a speed component in a rotation direction around rotation axis30. In short, in classification device1, rotating body3and each blade4rotate, so that it is possible to generate a swirling airflow in casing2. The swirling airflow is an airflow that rotates in a three-dimensional spiral shape.

Since the air flow (swirling flow) swirling in the inner space of casing2is generated in classification device1, a part of the particles in the air flowing into casing2from gas inflow port21of tubular portion20is discharged through particle discharge port23and particle discharge tubular portion5, and a part of the air containing the remaining particles flows out from gas outflow port22of tubular portion20.

In classification device1, the particles contained in the air flowing into casing2receive a centrifugal force in a direction from rotation axis30of rotating body3toward inner peripheral surface26of tubular portion20when rotating spirally in the inner space of casing2. The particles subjected to the centrifugal force are likely to spiral toward inner peripheral surface26of tubular portion20and rotate in the vicinity of inner peripheral surface26of tubular portion20along inner peripheral surface26. In classification device1, some of the particles in the air are discharged from particle discharge tubular portion5through particle discharge port23while passing through the inner space of casing2. The centrifugal force acting on the particles is proportional to the mass of the particles. Therefore, particles having a relatively large mass are likely to reach the vicinity of inner peripheral surface26of tubular portion20earlier than particles having a relatively small mass.

Furthermore, the centrifugal force acting on the particle is proportional to the mass of the particle and a radius of the circular motion of the particle. The radius of the circular motion is a distance between rotation axis30of rotating body3and the particle in a direction orthogonal to rotation axis30. When the mass of the particle is m, the velocity of the particle is v, and the radius of the circular motion is r, a magnitude of the centrifugal force is mv2/r. Here, when the angular velocity is ω, since v=rω, the magnitude of the centrifugal force is mω2r. In short, a centrifugal force having a magnitude proportional to the square of ω acts on the particles. Therefore, the magnitude of the centrifugal force acting on the particles can be changed by changing the rotation speed of rotating body3. Furthermore, when the rotation speed of rotating body3is the same, particles having a larger mass are more likely to reach the vicinity of inner peripheral surface26of tubular portion20before particles having a smaller mass.

In classification device1, as the rotation speed of rotating body3increases, particles having a smaller mass tend to be easily discharged from particle discharge port23. Regarding the powder particles, when the density of the particles is the same, a particle size of the particles is smaller as the mass of the particles is smaller.

In classification device1, control unit8controls a rotation speed of rotating body3by controlling drive unit7to change a classification diameter of the particles to be discharged from particle discharge port23.

In classification device1, when the powder is introduced from powder inlet port93while rotating body3and blades4are rotated and bypass flow path110is in use, the air flow containing first particles P1larger than the classification diameter and second particles P2smaller than the classification diameter is circulated through bypass flow path110, so that first particles P1are easily discharged from particle discharge port23. Therefore, classification efficiency can be improved.

In classification device1, control unit8controls the rotation speed of rotating body3according to the classification diameter of the particles to be discharged from particle discharge port23, for example. In classification device1, the particles remaining in the air without being discharged from particle discharge port23include particles having a particle size smaller than a classification diameter.

Classification device1according to the first exemplary embodiment includes casing2, rotating body3, blade4, drive unit7, and control unit8. Casing2includes tubular portion20having a circular inner peripheral shape. Rotating body3is disposed inside tubular portion20and is rotatable about rotation axis30along axial direction D1of tubular portion20. Blade4is disposed between tubular portion20and rotating body3, and rotates together with rotating body3. Drive unit7rotationally drives rotating body3. Control unit8controls drive unit7. Tubular portion20includes gas inflow port21, gas outflow port22that is separated from gas inflow port21in axial direction D1and allows the inside and the outside of tubular portion20to communicate with each other, and particle discharge port23. Classification device1further includes tubular member9and bypass flow path forming member11. Tubular member9includes an internal space communicating with gas inflow port21. Tubular member9includes powder inlet port93through which powder having a particle size distribution is introduced. Bypass flow path forming member11includes bypass flow path110constituted by an internal space communicating with gas inflow port21and gas outflow port22. Control unit8controls the rotation speed of rotating body3by controlling drive unit7to change a classification diameter of a particle to be discharged from particle discharge port23.

With the above configuration, classification device1according to the first exemplary embodiment can improve classification efficiency.

Furthermore, classification device1according to the first exemplary embodiment includes rotating body3and blade4that rotates together with rotating body3, and outflow tubular portion6protrudes in a direction along one tangential direction of outer peripheral surface27of tubular portion20, so that a pressure loss can be reduced.

Furthermore, classification device1according to the first exemplary embodiment includes rotating body3and blade4that rotates together with rotating body3, and outflow tubular portion6protrudes in the direction along one tangential direction of outer peripheral surface27of tubular portion20. Therefore, for example, by setting the pressure of gas outflow port22to be higher than the pressure of gas inflow port21by the design of outflow tubular portion6or the like, there is an advantage that it is not necessary to separately provide a blower for generating an air flow for conveying powder.

Second exemplary embodiment

Hereinafter, classification device1aaccording to a second exemplary embodiment will be described with reference toFIGS.6and7.FIG.6is a perspective view of classification device1aaccording to the second exemplary embodiment.FIG.7is a schematic diagram when particle discharge tubular portion5, first collection container140, and second collection container150are connected to classification device1aaccording to the second exemplary embodiment.

Classification device1aaccording to the second exemplary embodiment is substantially the same as classification device1according to the first exemplary embodiment (seeFIG.1), and is different from classification device1according to the first exemplary embodiment in that tubular portion20includes a plurality of particle discharge ports23separated from each other in axial direction D1of tubular portion20. Regarding classification device1aaccording to the second exemplary embodiment, the same components as those of classification device1according to the first exemplary embodiment are denoted by the same reference marks, and the description thereof will be omitted. Note that, inFIG.6, illustration of bypass flow path forming member11, switching unit12, tubular member9, control unit8, and the like inFIG.1is omitted.

Each of the plurality of particle discharge ports23has a slit shape elongated in a direction along an outer periphery of tubular portion20. Each of the plurality of particle discharge ports23has an arc shape as viewed in a direction along axial direction D1of tubular portion20. As illustrated inFIG.7, classification device1amay include a plurality of particle discharge tubular portions5corresponding to the plurality of particle discharge ports23on a one-to-one basis. As illustrated inFIG.7, similarly to classification device1, classification device1amay include first collection container140in which particles discharged through particle discharge port23and the particle discharge tubular portion enter for each set of particle discharge port23and the particle discharge tubular portion corresponding one-to-one. Furthermore, as illustrated inFIG.7, classification device1amay further include second collection container150into which the particles flowing out through gas outflow port22and outflow tubular portion6enter, similarly to classification device1.

Hereinafter, for convenience of description, the plurality of particle discharge ports23separated from each other in axial direction D1of tubular portion20may be referred to as first particle discharge port23A, second particle discharge port23B, third particle discharge port23C, and fourth particle discharge port23D in order of proximity to gas inflow port21.

Classification device1afurther includes a first opening and closing unit that opens and closes first particle discharge port23A, a second opening and closing unit that opens and closes second particle discharge port23B, a third opening and closing unit that opens and closes third particle discharge port23C, and a fourth opening and closing unit that opens and closes fourth particle discharge port23D. Control unit8exclusively controls the first opening and closing unit, the second opening and closing unit, the third opening and closing unit, and the fourth opening and closing unit. “Exclusively control” means that one opening and closing unit among the first opening and closing unit, the second opening and closing unit, the third opening and closing unit, and the fourth opening and closing unit is controlled to open the particle discharge port23corresponding to the opening and closing unit, and each of the remaining three opening and closing units is controlled to close the corresponding particle discharge port23. Therefore, control unit8performs a first control operation on a set of the first opening and closing unit, the second opening and closing unit, the third opening and closing unit, and the fourth opening and closing unit such that, for example, the first particle discharge port23A is opened and the second particle discharge port23B, the third particle discharge port23C, and the fourth particle discharge port23D are closed. Furthermore, control unit8performs a second control operation on the set of the first opening and closing unit, the second opening and closing unit, the third opening and closing unit, and the fourth opening and closing unit, for example, to open the second particle discharge port23B and close the first particle discharge port23A, the third particle discharge port23C, and the fourth particle discharge port23D. Furthermore, control unit8performs a third control operation on the set of the first opening and closing unit, the second opening and closing unit, the third opening and closing unit, and the fourth opening and closing unit, for example, to open the third particle discharge port23C and close the first particle discharge port23A, the second particle discharge port23B, and the fourth particle discharge port23D. Furthermore, control unit8performs a fourth control operation on the set of the first opening and closing unit, the second opening and closing unit, the third opening and closing unit, and the fourth opening and closing unit, for example, to open the fourth particle discharge port23D and close the first particle discharge port23A, the second particle discharge port23B, and the third particle discharge port23C.

Furthermore, control unit8varies the rotation speed of rotating body3in each of the first control operation, the second control operation, the third control operation, and the fourth control operation. In a case where the first control operation is performed on the set, control unit8controls drive unit7so as to rotate rotating body3at a first rotation speed. In a case where the second control operation is performed on the set, control unit8controls drive unit7so as to rotate rotating body3at a second rotation speed higher than the first rotation speed. In a case where the third control operation is performed on the set, control unit8controls drive unit7to rotate rotating body3at a third rotation speed higher than the second rotation speed. In a case where the fourth control operation is performed on the set, control unit8controls drive unit7to rotate rotating body3at a fourth rotation speed higher than the third rotation speed.

The above-described first rotation speed is determined in advance according to a first classification diameter, for example. The first classification diameter is a threshold value of the particle size of the particles to be discharged from the first particle discharge port23A.

The second rotation speed is determined in advance according to a second classification diameter smaller than the first classification diameter, for example. The second classification diameter is a threshold value of the particle size of the particles to be discharged from the second particle discharge port23B.

The third rotation speed is determined in advance according to a third classification diameter smaller than the second classification diameter, for example. The third classification diameter is a threshold value of the particle size of the particles to be discharged from the third particle discharge port23C.

The fourth rotation speed is determined in advance according to a fourth classification diameter smaller than the third classification diameter, for example. The fourth classification diameter is a threshold value of the particle size of the particles discharged from the fourth particle discharge port23D.

Classification device1aaccording to the second exemplary embodiment includes bypass flow path forming member11(seeFIG.1) similarly to classification device1according to the first exemplary embodiment, and thus, it is possible to improve the classification efficiency.

In a classification method according to the second exemplary embodiment, powder is classified using classification device1a. Classification device1aincludes casing2, rotating body3, and blade4. Casing2includes tubular portion20having a circular inner peripheral shape. Rotating body3is disposed inside tubular portion20and is rotatable about rotation axis30along axial direction D1of tubular portion20. Blade4is disposed between tubular portion20and rotating body3, and rotates together with rotating body3. The classification method includes, for example, a first step, a second step, a third step, and a fourth step. Note that, in the classification method, rotating body3and blade4are rotated in a state where opening63of outflow tubular portion6is not covered with opening and closing body121of switching unit12, but the present invention is not limited thereto. That is, in the classification method, classification device1is set to the first state in which bypass flow path110is used, but the present invention is not limited thereto, and classification device1may be set to the second state in which bypass flow path110is not used.

In the first step, rotating body3is rotated at the first rotation speed to classify particles having a first classification diameter or more from the powder. Note that, in the first step, control unit8performs the first control operation on the set, and then rotates rotating body3at the first rotation speed. Furthermore, in the first step, powder inlet port93is opened and the powder is introduced from powder inlet port93in a state where rotating body3is rotated at the first rotation speed. Powder inlet port93is closed except when powder is introduced.

In the second step, after the first step, rotating body3is rotated at the second rotation speed higher than the first rotation speed, and particles having a second classification diameter or more smaller than the first classification diameter are classified from the powder from which particles having the first classification diameter or more have been separated in the first step. Note that, in the second step, after performing the second control operation on the set, control unit8rotates rotating body3at the second rotation speed.

In the third step, rotating body3is rotated at the third rotation speed higher than the second rotation speed after the second step, and particles having a third classification diameter or more smaller than the second classification diameter are classified from the powder from which particles having the second classification diameter or more have been separated in the second step. Note that, in the third step, control unit8performs the third control operation on the set, and then rotates rotating body3at the third rotation speed.

In the fourth step, after the third step, rotating body3is rotated at the fourth rotation speed higher than the third rotation speed, and particles having a fourth classification diameter or more smaller than the third classification diameter are classified from the powder from which particles having the third classification diameter or more have been separated in the third step. Note that, in the fourth step, after performing the fourth control operation on the set, control unit8rotates rotating body3at the fourth rotation speed.

The classification method according to the second exemplary embodiment can improve the classification efficiency. Furthermore, the classification method according to the second exemplary embodiment can improve classification accuracy.

The classification method according to the second exemplary embodiment may include at least the first step and the second step among the first step to the fourth step.

Modifications

Each of the first and second exemplary embodiments is merely one of various exemplary embodiments of the present disclosure. The first and second exemplary embodiments can be variously modified according to design or the like as long as the object of the present disclosure can be achieved.

For example, tubular portion20in classification device1may have a plurality of gas outflow ports22. In this case, classification device1may include a plurality of outflow tubular portions6.

Furthermore, in classification device1according to the first exemplary embodiment, gas inflow port21penetrates in axial direction D1of tubular portion20(a surface including gas inflow port21intersects axial direction D1). However, the present invention is not limited thereto, and the surface including gas inflow port21may intersect a direction orthogonal to axial direction D1of tubular portion20.

Furthermore, in classification device1, the number of particle discharge ports23included in tubular portion20is not limited to a plurality, and may be one.

Furthermore, shapes of the plurality of particle discharge ports23are not limited to be the same as each other, and may be different from each other.

Furthermore, each of the plurality of blades4may have a distal end on a side of tubular portion20in the protruding direction from rotating body3located forward in rotation direction R1of rotating body3than a proximal end on a side of rotating body3.

Furthermore, each of the plurality of blades4may have a shape including one or more curved portions such as an arc shape.

Furthermore, each of the plurality of blades4may be formed in a spiral shape around rotation axis30of rotating body3. Here, the “spiral shape” is not limited to a spiral shape having one or more rotation speeds, and includes a partial shape of a spiral shape having one rotation speed.

Switching unit12is not limited to the configuration including one opening and closing body121, and may have a configuration including a first gate valve that opens and closes between inlet61and outlet62of outflow tubular portion6and a second gate valve that opens and closes an opening of first end111of bypass flow path forming member11.

Flow rate adjustment unit13is not limited to the configuration for adjusting the flow rate of gas inflow port21, for example, and may be configured to adjust the flow rate of gas outflow port22, for example.

The present specification discloses the following aspects.

Classification device (1;1a) according to a first aspect includes casing (2), rotating body (3), blade (4), drive unit (7), and control unit (8). Casing (2) includes tubular portion (20). Rotating body (3) is disposed inside tubular portion (20) and is rotatable about rotation axis (30) along axial direction (D1) of tubular portion (20). Blade (4) is disposed between tubular portion (20) and rotating body (3), and rotates together with rotating body (3). Drive unit (7) rotationally drives rotating body (3). Control unit (8) controls drive unit (7). Tubular portion (20) includes gas inflow port (21), gas outflow port (22) that is separated from gas inflow port (21) in axial direction (D1) and allows an inside and an outside of tubular portion (20) to communicate with each other, and particle discharge port (23). Classification device (1) further includes tubular member (9) and bypass flow path forming member (11). Tubular member (9) includes internal space (90) communicating with gas inflow port (21). Tubular member (9) includes powder inlet port (93) through which powder having a particle size distribution is introduced. Bypass flow path forming member (11) includes bypass flow path (110) communicating with gas inflow port (21) and gas outflow port (22). Control unit (8) controls a rotation speed of rotating body (3) by controlling drive unit (7) to change a classification diameter of a particle to be discharged from particle discharge port (23).

Classification device (1;1a) according to the first aspect can improve classification efficiency.

Classification device (1;1a) according to a second aspect, in the first aspect, further includes flow rate adjustment unit (13) that adjusts a flow rate of gas inflow port (21) or gas outflow port (22).

In classification device (1;1a) according to the second aspect, it is possible to suppress a decrease in the classification efficiency when the rotation speed of rotating body (3) is increased.

Classification device (1;1a) according to a third aspect, in the first aspect or the second aspect, further includes particle discharge tubular portion (5). Particle discharge tubular portion (5) includes internal space (50) communicating with particle discharge port (23) and protrudes from outer peripheral surface (27) of tubular portion (20). Particle discharge tubular portion (5) protrudes in a direction along a tangential direction of inner peripheral surface (26) of tubular portion (20) as viewed in axial direction (D1) of tubular portion (20).

In classification device (1;1a) according to the third aspect, particles passing near particle discharge port (23) are easily discharged through particle discharge port (23) and particle discharge tubular portion (5).

Classification device (1;1a) according to a fourth aspect, in any one of the first aspect to the third aspect, further includes switching unit (12) that switches between a first state in which bypass flow path (110) is used and a second state in which bypass flow path (110) is not used in classification device (1;1a).

Classification device (1;1a) according to a fifth aspect, in the fourth aspect, further includes outflow tubular portion (6). Switching unit (12) includes opening and closing body (121). Outflow tubular portion (6) includes internal space (60) communicating with gas outflow port (22), and protrudes from outer peripheral surface (27) of tubular portion (20). Opening and closing body (121) is disposed in outflow tubular portion (6). Outflow tubular portion (6) includes inlet (61) on a side of gas outflow port (22), outlet (62) on a side opposite to the side of gas outflow port (22), and opening (63) that allows internal space (60) of outflow tubular portion (6) and bypass flow path (110) of bypass flow path forming member (11) to communicate with each other. Opening and closing body (121) is rotatable between a first position where opening (63) is not covered and internal space (60) of outflow tubular portion (6) is partitioned into a space on a side of outlet (62) of outflow tubular portion (6) and spaces on a side of inlet (61) and a side of opening (63), and a second position where opening (63) is covered and outlet (62) of outflow tubular portion (6) communicates with gas outflow port (22).

A classification method according to a sixth aspect classifies powder using classification device (1a). Classification device (1a) includes casing (2), rotating body (3), and blade (4). Casing (2) includes tubular portion (20) having a circular inner peripheral shape. Rotating body (3) is disposed inside tubular portion (20) and is rotatable about rotation axis (30) along axial direction (D1) of tubular portion (20). Blade (4) is disposed between tubular portion (20) and rotating body (3), and rotates together with rotating body (3). The classification method includes a first step and a second step. In the first step, rotating body (3) is rotated at a first rotation speed to classify particles having a first classification diameter or more from the powder. In the second step, after the first step, rotating body (3) is rotated at a second rotation speed higher than the first rotation speed, and particles having a second classification diameter or more smaller than the first classification diameter are classified from the powder from which particles having the first classification diameter or more have been separated in the first step.

The classification method according to the sixth aspect can improve the classification efficiency.

INDUSTRIAL APPLICABILITY

The classification device and the classification method of the present disclosure can improve the classification efficiency. That is, the classification device and the classification method of the present disclosure are industrially useful because the classification device and the classification method can efficiently classify the powder.

REFERENCE MARKS IN THE DRAWINGS