JP4907655B2 - Airflow classifier and classification plant - Google Patents

Description

  The present invention relates to an airflow classifier and a classification plant that classify powder such as developing toner for a copying machine into fine powder and coarse powder.

  A device described in Patent Document 1 is conventionally known as an airflow classifier that rotates powder at high speed and centrifuges it into fine powder and coarse powder.

  FIG. 10 shows an airflow classifier described in Patent Document 1. This airflow classifier is provided with a classification plate 81 inclined in an upward gradient from the outer periphery toward the center in the casing 80, a classification cover 82 is provided on the classification plate 81, and between the classification cover 82 and the classification plate 81. A plurality of louvers are annularly arranged on the peripheral wall of the classification chamber 83 formed in the above, and an inflow passage 84 through which secondary air swirls and flows into the classification chamber 83 is provided between adjacent louvers.

  Further, a powder guide tube 85 is provided at the upper part of the casing 80, and a powder supply tube 86 facing in a tangential direction is provided on the outer periphery of the upper part of the powder guide tube 85. Is supplied with a solid-gas mixed fluid of powder and high-pressure air, and the powder that descends while rotating around the outer periphery of the powder guide cylinder 85 is classified from a powder supply port 87 provided on the outer periphery of the classification cover 82. The powder is swirled into the chamber 83 while being swirled, and the swirling speed of the powder is accelerated by the secondary air flowing into the classification chamber 83 from the inflow passage 84 to centrifuge the powder into fine powder and coarse powder. The fine powder that moves to the central portion is sucked into the fine powder discharge cylinder 88 connected to the central portion of the classification plate 81.

In addition, coarse powder swirling around the outer periphery of the classification chamber 83 is discharged from a coarse powder discharge port 89 formed on the outer periphery of the classification plate 81.
Japanese Patent Laid-Open No. 11-138103

  By the way, in the conventional airflow classifier, when the powder swirls in the classification chamber 83, secondary air is caused to flow into the classification chamber 83 from the inflow path 84, and the swirl speed of the powder is accelerated by the secondary air. Therefore, the swirling vortex is disturbed by the confluence of the swirling airflow of the solid-gas mixed fluid flowing into the classification chamber 83 and the swirling airflow of the secondary air, and the powder cannot be swirled cleanly at high speed. I cannot do a good classification. In addition, the amount of air flowing into the classification chamber 83 from the powder guide cylinder 85 is large, and the point to be improved such that the centered speed acting on the particles increases and the separated particle diameter cannot be reduced is left. It was.

  Further, since the powder is classified in the single classification chamber 83, the classification is performed by increasing the height of the classification chamber 83 or adjusting the volume by increasing the inner diameter to adjust the classification point of the powder. Since the swirling speed of the powder in the chamber 83 decreases and the powder cannot be accurately centrifuged, the powder and air mixing ratio is high in the restricted small volume classification chamber 83. It becomes necessary to perform classification. For this reason, it cannot be said that the classification accuracy is good, and there are still points to be improved in improving the classification accuracy.

  Furthermore, since it is necessary to flow the secondary air into the classification chamber 83 by suction to accelerate the swirling airflow, the amount of air in the classification chamber 83 increases, and a blower that applies suction to the fine powder discharge cylinder 88 is an air volume. It is necessary to use a large-sized one having a large size. In addition, accessories such as a cyclone separator that separates the mixed fluid conveyed by air from the fine powder discharge cylinder 88 into fine powder and air, and a bag filter that collects powder from the separated air are also proportional to the air volume. Since it is necessary to increase the size, the equipment cost becomes high, and there are still points to be improved in order to reduce the cost.

  In general, in a toner used in an image forming apparatus such as a copying machine, if a toner having a particle size larger than necessary or a toner smaller than necessary is contained, a clear image cannot be formed. Therefore, in the toner manufacturing plant, the fine powder classified by the first air flow classifier is supplied to the second air flow classifier, the fine powder is classified into fine powder and ultra fine powder, and the fine powder is used as a product. Yes.

  By the way, in recent toner production, it is required to reduce the particle size of the product and to improve the accuracy of the particle size distribution. However, in the conventional air classifier, it is difficult to obtain the accuracy because of the structure.

  Therefore, conventionally, since the fine powder classified by the first stage air classifier is reclassified by the second stage air classifier to produce a small particle size toner, two series of air classifiers are required, Equipment costs and running costs are high.

  An object of the present invention is to provide an airflow classifier and a classifier capable of classifying powders with a small particle size with high accuracy with a single stage classifier and reducing the equipment cost and running cost. Is to provide a plant.

  In order to solve the above-mentioned problems, in the airflow classifier according to the present invention, a classification plate is provided in the casing, a substantially cylindrical primary classification chamber on the outer periphery of the upper surface of the classification plate in the casing, and its primary A secondary classification chamber having a substantially cylindrical or conical shape with a smaller diameter than the primary classification chamber is provided on the same axis as the classification chamber, and primary classification is performed by jetting high-pressure air or suctioning external air to the lower part of the peripheral wall of the primary classification chamber. An air nozzle that forms a swirling airflow is provided in the room, a coarse powder discharge port is formed between the outer periphery of the classification plate and the inner peripheral surface of the casing, and a fine powder discharge tube is provided at the fine powder suction port formed at the center of the classification plate. An annular powder supply header is provided on the outer peripheral portion of the peripheral wall of the secondary classification chamber, and a powder supply cylinder for supplying powder in the circumferential direction of the inner periphery is connected to the powder supply header. At the same time, powder is supplied to the inner peripheral wall of the powder supply header. The powder to pivot the header is of employing the configuration to form the inlet to pivot flow into the upper portion of the primary classification chamber or secondary classifying chamber in the lower.

  In the airflow classifier configured as described above, when high pressure air is sprayed from the air nozzle toward the outer peripheral portion of the primary classification chamber or suction of external air in a state in which suction force is applied to the fine powder discharge cylinder, A swirling airflow is formed, and the swirling airflow moves inward in the radial direction. When the swirling airflow moves to the position of the lower end opening of the secondary classification chamber, the swirling airflow moves upward while swirling along the inner peripheral wall of the secondary classification chamber.

  As described above, when the powder fed into the powder supply header is swirled into the secondary classification chamber through the inflow hole in the state where the swirling airflow is formed in the primary classification chamber and the secondary classification chamber, the powder is It will turn on the flow of the swirling airflow.

  When supplying powder, a swirling airflow is formed in the secondary classification chamber. The swirling airflow is created by the swirling airflow and a small amount of high-pressure air in the powder supply header. Although the airflow merges, the swirling airflow passes through the narrowed inflow hole and the amount of air is small, so the swirling airflow in the secondary classification chamber is not affected by the swirling airflow in the powder supply header. The powder can be classified with high accuracy in the secondary classification chamber.

  In addition, the position of the inflow hole through which the powder flows in is higher than the coarse powder outlet and is located on the inner diameter side of the coarse powder outlet, so that the powder immediately flows into the coarse powder outlet. There is nothing wrong.

  For this reason, almost all of the supplied powder is swirled in the flow of the swirling airflow and centrifuged into coarse powder and intermediate powder (fine powder partially containing coarse powder), and the coarse powder is primary classified The coarse powder that flows down into the room and is further dispersed and classified by the swirling airflow swirling in the primary classification chamber is discharged to the coarse powder discharge port, and the intermediate powder is discharged into the secondary classification chamber. Ascend while turning.

  On the other hand, when the fine powder contained in the coarse powder moves inward of the primary classification chamber and moves to a position facing the outer periphery of the secondary classification chamber, it merges with the intermediate powder swirling in the secondary classification chamber, Ascending while turning along the inner surface of the peripheral wall of the secondary classification chamber, and when reaching the ceiling surface of the secondary classification chamber, the direction is changed radially inward along the ceiling surface.

  At this time, a suction force is applied to the fine powder suction port, and the suction force acts on the central portion of the secondary classification chamber. Therefore, the intermediate powder moved radially inward along the ceiling surface is secondary classified. The flow changes downward in the center of the chamber and descends while creating a swirling vortex. The inner diameter of the descending swirl vortex is almost equal to the diameter of the fine powder suction port and is much smaller than the inner diameter of the secondary classification chamber, so the flow speed of the swirl vortex is faster and the intermediate powder is effective for coarse and fine powders. Centrifugal separation is performed, and the coarse powder swirls and descends while spreading outward in the radial direction, flows into the primary classification chamber, is centrifuged in the primary classification chamber, and is discharged from the coarse powder outlet. On the other hand, the fine powder descends on the swirling vortex and is sucked and discharged from the fine powder suction port together with air.

  Here, if there is uneven speed in the swirling airflow formed in the primary classification chamber by injection of high pressure air from the air nozzle or suction of external air, the air is discharged from the coarse powder outlet in a state where fine powder is mixed into the coarse powder. There is a possibility. In order to suppress the speed variation of the swirling airflow, it is preferable that a plurality of air nozzles are provided and the plurality of air nozzles are provided at equal intervals around the outer peripheral wall of the primary classification chamber.

In this case, by providing a ring-shaped air supply header that supplies high-pressure air to each of the plurality of air nozzles and an air supply cylinder that sends high-pressure air to the air supply header around the outer peripheral wall of the primary classification chamber. Since the same amount of high-pressure air is ejected from each of the air nozzles at the same pressure, the speed variation of the swirling airflow can be suppressed and a swirling airflow having a uniform speed can be formed over the entire circumferential direction.
Further, when sucking the external air, a uniform swirling airflow can be formed even if the air supply header is removed.

  Here, a large number of vanes inclined in the circumferential direction are provided at equal intervals on the inner peripheral portion of the ring-shaped air supply header, and the air nozzles between adjacent vanes are used to rotate at a more uniform speed over the entire circumferential direction. An air flow can be formed.

  In addition, if the swirl vortex formed in the center of the secondary classification chamber becomes unstable and moves in the radial direction of the secondary classification chamber, there is a possibility that accurate classification cannot be performed. It is preferable to stabilize the swirling vortex by providing a conical or cylindrical center core at the center of the top wall of the classification chamber. In this case, if the exhaust port is formed on the center axis of the center core, the air in the secondary classification chamber can be exhausted from the exhaust port, so the exhaust resistance is reduced and the pressure in the primary classification chamber and the secondary classification chamber is abnormal. As a blower for applying a suction force to the fine powder discharge cylinder or a blower for supplying high-pressure air to the air supply cylinder, a small one can be adopted. It is also possible to obtain fine powder having different particle diameters at the exhaust port and the fine powder discharge cylinder.

  In the airflow classifier according to the present invention, the classification point can be adjusted if the height dimension of the primary classification chamber can be adjusted, or the height dimension of the secondary classification chamber can be adjusted.

  In addition, if the secondary classification chamber is divided into multiple stages in the vertical direction and the inner diameter is made smaller as it reaches the upper stage of the secondary classification chamber, the powder is classified in each classification chamber of the secondary classification chamber. In addition, since the swirl diameter of the airflow decreases and the speed increases as it reaches the secondary classification chamber on the upper stage side, it is possible to obtain a fine powder having a very small particle diameter with very little coarse powder mixed therein.

  Further, if the inflow hole is an annular slit or a plurality of arc-shaped slits arranged at intervals in the circumferential direction, the powder is substantially uniform from the entire circumferential direction of the secondary classification chamber or the primary classification chamber. Since the powder is supplied, the powder can be classified extremely effectively.

  In the first classifying plant according to the present invention, the air classifier, a solid-gas separator that separates the solid-gas mixed fluid fed from the fine powder discharge cylinder of the air classifier into fine powder and air, and A dust collector that collects powder in the air fed from the air outlet of the solid-gas separator and clarifies the air, and a blower that applies suction to the dust collector or sends high-pressure air to the air nozzle; The structure which consists of was adopted.

  Here, a pulverizer that pulverizes the powder is connected to the lower end outlet of the casing of the airflow classifier, and circulates between the powder outlet portion of the pulverizer and the powder supply cylinder that supplies the powder to the powder supply header. When the powder supply pipe is connected in the middle of the circulation path, the coarse powder discharged from the lower end opening of the casing is pulverized by the pulverizer and returned to the powder supply header. The powder supply header Therefore, it is sent to the air classifier and subjected to the classification process again, so that a product with a precise particle size distribution can be obtained.

  From the second airflow classifier that classifies the fine powder fed from the powder outlet of the solid-gas separator of the first classification plant into the fine powder and the ultrafine powder that are the products, and the second airflow classifier The second solid-gas separator that separates the solid-gas mixed fluid that is sent into ultrafine powder and air, and the air powder that is sent from the solid-gas separator is collected to clarify the air. When the second dust collector is provided, the fine powder classified in one of the airflow classifiers can be continuously classified in the second airflow classifier. Small fine powder is collected by a bag filter, and fine powder with a small particle size distribution width can be obtained. For this reason, when the toner is manufactured, the toner can be manufactured continuously, and the toner can be manufactured extremely efficiently.

  In the second classification plant according to the present invention, a classification chamber is formed on a classification plate provided in the casing, and the powder is swirled at a high speed in the classification chamber and centrifuged into coarse powder and fine powder. Airflow classifier for primary treatment that discharges powder from the coarse powder discharge port formed on the outer periphery of the classification plate and discharges the fine powder from the fine powder discharge tube connected to the center of the classification plate, and its airflow classifier A pulverizer that pulverizes coarse powder discharged from the lower end of the casing and circulates the pulverized powder into a classification chamber of the airflow classifier; and a solid-gas mixed fluid fed from the fine powder discharge cylinder -Air separation machine for separating air and air, air-flow classifier for secondary treatment according to the present invention for classifying fine powder fed from the solid-gas separator, and air-flow classifier for the secondary treatment The solid-gas mixed fluid fed from the fine powder discharge cylinder A solid-gas separator that separates the air and ultrafine powder, a dust collector that collects the powder in the air sent from the air outlet of the solid-gas separator and clarifies the air, and a suction force to the dust collector Or a blower that feeds high-pressure air into the air supply cylinder is employed.

  As described above, in the airflow classifier according to the present invention, when high-pressure air is injected from the air nozzle into the primary classification chamber, the high-pressure air swirls in the primary classification chamber to form a swirling airflow, and the swirling airflow is Since the swirl flow of the powder that swirls along the inner surface of the peripheral wall of the secondary classification chamber and is swirled in the powder supply header is supplied from the narrow inlet hole, the swirl flow is swirled in the secondary classification chamber. The swirling airflow is not disturbed, and the powder can be classified with high accuracy.

  In the primary classification chamber, the powder is first classified into coarse powder and intermediate powder (fine powder partially containing coarse powder), and then the intermediate powder is led to the secondary classification chamber to be classified into coarse powder and fine powder. As a result, the coarse powder is less likely to be mixed in the fine powder, and an accurate classification process can be performed. For this reason, processing was conventionally performed using a two-stage air classifier, but it can be processed using a one-stage air classifier.

  Furthermore, since the classification process is performed with a small amount of air for supplying powder, the amount of air in the classification chamber can be reduced. Therefore, in the classification plant that employs the airflow classifier of the present invention, a small blower can be employed, and a solid-gas separator for collecting fine powder, and powder in air separated from the solid-gas separator Since a small-sized dust collector can be employed as a dust collector that collects water, facility costs and running costs can be reduced.

  Further, as in the second classifying plant, the fine powder classified by the primary airflow classifier is classified by the secondary airflow classifier according to the present invention, thereby mixing coarse powder and ultrafine powder. A fine powder with a very small particle size distribution width can be obtained.

Schematic showing an embodiment of an air classifier according to the present invention Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG. Sectional view showing details of the upper part of the air classifier Schematic diagram of a classification plant using the air classifier shown in FIG. Sectional drawing which shows the other example of an air nozzle Schematic which shows the other example of the classification plant using the airflow classifier shown in FIG. Schematic which shows the further another example of the classification plant using the airflow classifier shown in FIG. Schematic showing another example of a classification plant according to the present invention Schematic showing a conventional air classifier

Explanation of symbols

A ₁ Airflow classifier A ₂ Airflow classifier B Classification plant 2 Casing 7 Classification plate 8 Coarse powder discharge port 11 Fine powder suction port 12 Fine powder discharge tube 13 Primary classification chamber 16 Secondary classification chamber 16a Upper side secondary classification chamber 16b Lower side Secondary classification chamber 26 Center core 26c Exhaust hole 27 Conical surface 31 Air supply header 33 Air nozzle 34 Powder supply header 35 Powder supply cylinder 36 Inflow hole 40 Jet mill (pulverizer)
43 Circulating path 52 Powder supply pipe 62 Cyclone separator (solid-gas separator)
70 Bag filter (dust collector)
72 Blower 73 Blower 80 Casing

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4 show an embodiment of an air classifier according to the present invention. As illustrated, the air flow classifier A ₁ has a casing 2. The casing 2 is divided into an upper casing 3 and a lower casing 4, and a support cylinder 5 having an internal thread formed on the inner periphery is provided on the central axis of the lower casing 4.

  The support cylinder 5 is fixedly arranged, and a plurality of spacers 6 are incorporated on an inward flange 5a provided at the lower end thereof. Further, a screw cylinder 7 a provided at the center of the lower surface of the classification plate 7 is screwed to the support cylinder 5.

  The classification plate 7 is adjusted in height by increasing or decreasing the number of spacers 6 incorporated in the support cylinder 5.

  The upper surface of the classification plate 7 has a conical shape inclined with an upward gradient from the outer periphery toward the center, and an annular coarse powder discharge port 8 is provided between the outer periphery and the inner periphery of the casing 2. In the embodiment, the classification plate 7 has a conical shape, but may have a flat plate shape.

  The inner peripheral upper part of the screw cylinder 7a is a tapered hole 9, and a tapered ring 10 is detachably fitted in the tapered hole 9. The inside of the taper ring 10 is a fine powder suction port 11. As the taper ring 10, here, a taper-shaped fine powder suction port 11 whose upper end is a small-diameter end is adopted, but there are various types such as a tapering having a taper-shaped fine powder suction port whose upper end is a large-diameter end. A thing with a large aperture can be used.

  The upper part of the fine powder discharge cylinder 12 is connected to the support cylinder 5. The fine powder discharge cylinder 12 has an L shape, and the tip portion penetrates a part of the lower casing 4 and faces the outside.

  The upper casing 3 includes a skirt portion 14 that forms a primary classification chamber 13 with the outer peripheral portion of the upper surface of the classification plate 7, and a cylindrical portion 15 that rises from the inner diameter portion of the skirt portion 14. The inner side is a secondary classification chamber 16.

  Here, the skirt portion 14 has an inclination parallel to the classification plate 7, but may be a horizontal shape without inclination or a inclination larger than the classification plate.

  A plurality of spacers 17 are incorporated between the facing surfaces of the skirt portion 14 and the lower casing 4, and the height dimension of the primary classification chamber 13 can be adjusted by increasing or decreasing the number of the spacers 17.

  The cylindrical portion 15 is a stepped cylindrical portion including a lid 15a, an upper ring 15b whose upper end opening is closed by the lid 15a, and a lower ring 15c having a diameter larger than that of the upper ring 15b. The secondary classification chamber 16 in the section 15 is divided into an upper secondary classification chamber 16a in the upper ring 15b and a lower secondary classification chamber 16b in the lower ring 15c.

  Here, the height of the upper secondary classification chamber 16a can be adjusted by replacing the upper ring 15b with an upper ring having a different height, and the lower secondary classification chamber 16b also has a lower ring 15c. The height can be adjusted by changing to a different lower ring. Instead of replacing the upper ring 15b, the upper wall of the upper secondary classification chamber 16a may be moved up and down to adjust the height of the upper secondary classification chamber 16a. The height of the secondary classification chamber 16b may be adjusted. Moreover, although the cylindrical thing was shown here as the upper stage side secondary classification chamber 16a, it is good also as a cone shape which becomes a small diameter as it goes up.

  The lid 15a, the upper ring 15b, and the lower ring 15c are held in an assembled state that forms the upper casing 3 by the connecting means 20. Here, as the connecting means 20, a plurality of support pieces 21 are provided on the outer peripheral upper portion of the lower casing 4, and the upper portion of the screw shaft 22 whose lower end is fixed to each support piece 21 is fixed to the upper surface of the top wall of the lid 15a. The connecting piece 23 is passed through, and a knob 24 is screwed to the upper end portion of the screw shaft 22 to be tightened.

  A core insertion hole 25 is formed in the center of the top wall of the lid 15a, and a center core 26 is slidably inserted into the core insertion hole 25. The center core 26 includes an outer core 26a and an inner core 26b that is slidably inserted into the outer core 26a. A conical surface 27 is provided below the outer core 26a and the inner core 26b.

  An exhaust port 26c is formed on the central axis of the inner core 26b. A flange 28 is provided at the upper end of the inner core 26b, and a height adjustment ring 29 is assembled between the flange 28 and the upper ring lid 15a. Therefore, the length of the inner core 26b protruding into the secondary classification chamber 16 can be adjusted by replacing the height adjusting ring 29 with another height adjusting ring 29 having a different length. A bolt 30 for fixing 26 is screwed into the lid body 15a.

  An annular air supply header 31 is provided outside the joint portion between the upper casing 3 and the lower casing 4, and an air supply cylinder 32 is connected to the outer periphery facing position of the air supply header 31.

  A plurality of air nozzles 33 are provided at equal intervals on the inner periphery of the air supply header 31. Each air nozzle 33 injects the high-pressure air supplied in the air supply header 31 toward the outer peripheral portion circumferential direction in the primary classification chamber 13.

  An annular powder supply header 34 is provided on the outer periphery of the lower ring 15c, and a plurality of powder supply cylinders 35 are connected to the powder supply header 34 at equiangular positions. The powder supply cylinder 35 is configured to inject powder in the circumferential direction of the outer periphery of the powder supply header 34, and is injected into the primary classification chamber 13 from the injection direction of the powder and the air nozzle 33. The direction is the same as the high-pressure air injection direction.

  The inner peripheral wall of the powder supply header 34 is provided with an inflow hole 36 formed of an annular slit through which the powder swirling inside swirls and flows into the lower secondary classification chamber 16b. The inflow hole 36 may be opened at the upper part of the peripheral wall of the primary classification chamber 13 so that the powder swirls and flows into the outer periphery of the upper part of the primary classification chamber 13, or the powder supply header 34 is connected to the upper side. You may provide in the outer peripheral part of the surrounding wall of a secondary classification chamber. Furthermore, it may be formed on the bottom wall of the powder supply header 34 so that the powder swirls downward from the upper part of the lower secondary classification chamber 16b. The inflow hole 36 may be formed of a plurality of arc-shaped slits arranged in an annular shape.

Figure 5 shows a classification plant employing the air classifier A ₁ having the above-described configuration. In this classification the plant, connects the powder supplying device 50 to the powder supply tube 35 of the air classifier A _1. The powder supply device 50 sucks and disperses the powder in the hopper 53 by high-pressure air injected from the air injection nozzle 51 into the powder supply pipe 52, and sends the powder into the powder supply cylinder 35 through the powder supply pipe 52. I am doing so.

It is classified by the air classifier A _1, fines are sucked and discharged to the fine powder discharge cylinder 12 is adapted to be fed into the cyclone separator 62 as a solid-gas separator from fine feed channel 61.

  The cyclone separator 62 separates fine powder and air. Fine powder as a product is discharged from the outlet 63 at the lower end, and air is sent from the air supply path 64 to a bag filter 70 as a dust collector.

  The bag filter 70 collects powder contained in the air. The clarified air is sucked by the blower 72 and discharged to the outside.

Now, operating the blower 72, in a state that applies suction to the fine powder discharge tube 12, is supplied to the high-pressure air to the air supply cylinder 32 of the air classifier A ₁ shown in FIG. 4, the high-pressure air is air supply header 31 Are sent to the plurality of air nozzles 33, and injected from the air nozzles 33 in the circumferential direction of the outer peripheral portion in the primary classification chamber 13.

  At this time, since the plurality of air nozzles 33 are provided at equal intervals, the high-pressure air is evenly supplied into the primary classification chamber 13 and swirls at a high speed in the primary classification chamber 13 to form a swirling airflow.

  When the swirling airflow moves radially inward in the primary classification chamber 13 and moves to the position of the lower end opening of the lower secondary classification chamber 16b of the secondary classification chamber 16, the peripheral wall of the lower secondary classification chamber 16b It moves upward while turning along the inner surface.

  As described above, when powder is supplied from the powder supply device 50 into the powder supply header 34 in a state where a swirling airflow is formed in the primary classification chamber 13 and the lower secondary classification chamber 16b, the powder flows in. It swirls and flows into the lower secondary classification chamber 16b from the hole 36, and swirls on the flow of the swirling airflow formed in the lower secondary classification chamber 16b.

  Here, when the powder is supplied, a swirling airflow is formed in the lower secondary classification chamber 16b, and the swirling airflow of the powder that is jetted from the powder supply cylinder 35 into the powder supply header 34 and swirls is Since it flows in through the inflow hole 36 formed of a narrow slit, the swirling airflow swirling in the lower secondary classification chamber 16b is not disturbed, and the powder in the lower secondary classification chamber 16b is not disturbed. It can be turned at high speed.

  Due to the swirling flow of the powder in the lower secondary classification chamber 16b, the powder is classified into coarse powder and intermediate powder (fine powder partially containing coarse powder), and the coarse powder is in the primary classification chamber 13. The coarse powder dispersed and reclassified by the swirling airflow swirling in the primary classification chamber 13 and reclassified and swirling on the outer periphery of the primary classification chamber 13 is discharged to the coarse powder discharge port 8.

  On the other hand, when the fine powder separated from the coarse powder moves inward of the primary classification chamber 13 and moves to a position facing the outer peripheral portion of the lower secondary classification chamber 16b, it enters the lower secondary classification chamber 16b. Then, it merges with the intermediate powder swirling in the lower secondary classification chamber 16b, and ascends along the inner surface of the peripheral wall of the lower secondary classification chamber 16b.

  The intermediate powder swirling in the lower secondary classification chamber 16b is again classified into coarse powder and fine powder, the coarse powder descends and enters the primary classification chamber 13, and is classified again in the primary classification chamber 13, It is discharged from the coarse powder outlet 8.

  On the other hand, the fine powder rises while swirling, and when it reaches the lower end of the upper secondary classification chamber 16a, it enters the upper secondary classification chamber 16a and rises while swirling.

  For this reason, the fine powder is again centrifuged into fine powder and coarse powder in the upper secondary classification chamber 16a, and the coarse powder descends and enters the lower secondary classification chamber 16b and the primary classification chamber 13, each chamber. Classification is performed again at 16b and 13.

  On the other hand, the fine powder rises while swirling, and when it reaches the ceiling surface of the upper secondary side classification chamber 16a, it changes its direction radially inward along the ceiling surface.

  The fine powder that has moved inward in the radial direction along the ceiling surface of the upper secondary classification chamber 16 a changes its flow downward along the outer periphery of the center core 26. At this time, since the suction force of the blower 72 is acting on the fine powder suction port 11, the fine powder whose flow is changed downwardly descends while forming a swirl vortex.

  The inner diameter of the swirl vortex is a small diameter that is almost equal to the minimum inner diameter of the fine powder suction port 11 and is very small compared to the swirl vortex diameter at the time of ascent. Effectively centrifuged.

  The separated coarse powder swirls and descends while spreading outward in the radial direction, reflows into the primary classification chamber 13, is centrifuged again on the swirl flow in the primary classification chamber 13, and moves to the outer periphery. The powder is discharged from the coarse powder outlet 8. On the other hand, the fine powder descends along the swirl vortex and is sucked into the fine powder suction port 11.

  Thus, since the powder is continuously centrifuged in the primary classification chamber 13, the lower secondary classification chamber 16b, and the upper secondary classification chamber 16a several times in succession, efficient classification can be performed. At the same time, it is possible to perform an accurate classification process in which the fine powder is not mixed into the coarse powder side and the coarse powder is hardly mixed into the fine powder side.

  The intermediate powder flowing into the upper-stage secondary classification chamber 16a has most of the coarse powder removed in the primary-classification chamber 13 and the lower-stage classification chamber 16b, so that the mixing ratio between the powder and the high-pressure air is low. The swirl vortex formed at the center of the secondary classification chamber 16 is a swirl vortex with a small inner diameter and a high swirl speed, so that the powder can be classified with extremely high accuracy. Here, by forming the upper secondary classification chamber 16a of the secondary classification chamber 16 in a conical shape, the turning speed of the intermediate powder increases as it goes upward, and the classification accuracy can be further increased.

  Furthermore, since the powder can be supplied into the lower secondary classification chamber 16b with a small amount of high-pressure air, a small blower 72 can be adopted. Further, the cyclone separator 62 for collecting fine powder and the bag filter 70 for collecting the powder in the air can be small, and the apparatus can be downsized and the equipment cost and running cost can be reduced. it can.

  As shown in the embodiment, the flow velocity of the swirling flow can be adjusted by adjusting the height dimension of the primary classification chamber 13 and the secondary classification chamber 16 or the inner diameter of the secondary classification chamber. The point can be adjusted. Furthermore, the classification point can also be adjusted by changing the inner diameter of the fine powder suction port 11.

  Further, by providing the center core 26, a stable swirl vortex can be formed. Further, by changing the number of the air nozzles 33 or the cross-sectional area of the air nozzles 33, the swirling speed and dispersion state of the solid-gas mixed fluid supplied to the primary classification chamber 13 can be adjusted.

  Further, if the exhaust port 26c is formed on the central axis of the inner core 26b that forms the center core 26, a part of the air in the classification chamber is exhausted from the exhaust port 26c, and the exhaust resistance becomes small. The pressure in the next classification chamber 16 can be prevented from rising abnormally, and a small blower 72 that applies a suction force to the fine powder discharge cylinder 12 can be adopted. It is also possible to obtain powder having different particle sizes between the exhaust port 26c and the fine powder discharge cylinder 12. In addition, by providing the damper D above the exhaust port 26c, it is possible to adjust the exhaust amount by adjusting the opening degree of the damper D and change the powder diameter.

  In the airflow classifier shown in FIG. 4, the secondary classification chamber 16 is divided into two stages up and down, but it may be divided into three stages or more without being divided into a single secondary classification room. Good.

  In FIG. 3, the plurality of air nozzles 33 provided on the inner periphery of the air supply header 31 are formed of a cylindrical body. However, as illustrated in FIG. A large number of vanes 37 inclined in the circumferential direction are provided at equal intervals, and the air nozzles 33 are provided between the adjacent vanes 37 to be fed into the air supply header 31 from a plurality of air supply cylinders 32 extending in the tangential direction of the air supply header 31. The high-pressure air that is generated may be swirled into the primary classification chamber 13 from the air nozzles 33.

  In this case, a large number of vanes 37 may be supported so as to be swingable, and the injection angle and opening of the high-pressure air may be adjusted by adjusting the angle by swinging each vane 37.

  Further, in the classification plant shown in FIG. 5, the fine powder is sucked into the fine powder discharge cylinder 12 by the blower 72. However, instead of the blower 72, as shown by the chain line in FIG. The fine powder may be caused to flow into the fine powder discharge cylinder 12 by pushing high-pressure air discharged from the blower 73 into the inside, or the fine powder may be flowed into the fine powder discharge cylinder 12 by using the blowers 72 and 73 together. You may make it make it.

In FIG. 5, high-pressure air is sent to the air supply cylinder 32, and the high-pressure air is injected from the air nozzle 33 to the outer peripheral portion of the primary classification chamber 13 to form a swirling airflow in the primary classification chamber 13. The blower 72 shown in FIG. 5 is a large-sized one capable of providing a high degree of vacuum to the primary classification chamber 13 and the secondary classification chamber 16 of the airflow classifier A ₁ , and the primary classification chamber by driving the blower 72. The external air may be sucked into the primary classification chamber 16 from the air nozzle 33 due to a decrease in the pressure in the air pressure 13 to form a swirling airflow. In this case, the air supply header 31 can be eliminated.

FIG. 7 shows another example of the classification plant. In this example, so as to supply coarse powder discharged from the lower end outlet 2a of the casing 2 of the air classifier A ₁ in the hopper 41 of the jet mill 40 as the grinding machine.

  Conventionally, the jet mill 40 guides coarse powder supplied into the hopper 41 by high-pressure air ejected from an air nozzle 42 into a grinding chamber (not shown), and collides with a collision plate provided in the grinding chamber. Since it is well known, its details are omitted.

  The powder pulverized by the jet mill 40 is sent into the powder supply cylinder 35 from the circulation path 43 together with high-pressure air.

As shown in FIG. 7, the coarse powder is discharged from the air classifier A ₁ was pulverized with a jet mill 40, the powder after pulverization treatment was circulated by feeding the powder feed pipe 35, repeating the pulverization and classification Thus, a product with a precise particle size distribution can be obtained.

  FIG. 8 shows still another example of the classification plant. In the classification plant shown in this example, two classification plants B shown in FIG. 5 are adopted, and fine powder taken out from the cyclone separator 62 of one classification plant B is fed into the powder supply cylinder 35 of the other classification plant B. Then, classification is performed again, and ultrafine powder taken out from the cyclone separator 62 of the other classification plant B is used as a product.

In the classification plant, coarse powder can be collected in one classification plant B, and fine powder and ultrafine powder can be collected in the other classification plant B, and can be classified into three types.
In addition, it can also classify | categorize into many types by repeating a classification.

FIG. 9 shows still another example of the classification plant. In this example, in place of the air classifier A ₁ of one classifying plant B shown in FIG. 8, employs a conventional air classifier A ₂ shown in FIG. 10, the lower end of the casing 80 of the air classifier A ₂ A hopper 41 of a jet mill 40 as a pulverizer is connected to the pulverizer, and the powder pulverized by the jet mill 40 is fed from the circulation path 43 to the powder supply cylinder 86. Since other configurations are the same as those in FIG. 8, the same components are denoted by the same reference numerals and description thereof is omitted.

Also in the above classification plant, similarly to the classifying plant of FIG 8, it is possible to classification treatment are continuously classification treatment micronized by air classifier A ₂ in the other classification plant B of one of the classification plant B, It is possible to obtain a product powder (fine powder) having a fine particle size distribution with less coarse and ultra fine powders. For this reason, when the toner is manufactured, the toner can be manufactured continuously, and the toner can be manufactured extremely efficiently.

In the classification plant of FIG. 9, the airflow classifier A2 shown in FIG. 10 is adopted as the _first airflow classifier, but the powder is supplied into the classification chamber, and the powder is swirled at high speed to produce coarse and fine powder. Any air classifier may be used as long as the air classifier is classified into two types.

Claims (12)

  A classification plate is provided in the casing, and a substantially cylindrical primary classification chamber on the outer periphery of the upper surface of the classification plate in the casing, and a substantially cylindrical or conical shape having a smaller diameter than the primary classification chamber on the same axis as the primary classification chamber A secondary classification chamber, an air nozzle that forms a swirling airflow in the primary classification chamber by jetting high-pressure air or sucking external air is provided at the lower peripheral wall of the primary classification chamber, and the outer periphery of the classification plate and the casing A coarse powder discharge port is formed between the inner peripheral surfaces, a fine powder discharge tube is connected to a fine powder suction port formed at the center of the classification plate, and an annular powder supply header is provided on the outer peripheral portion of the peripheral wall of the secondary classification chamber The powder supply header is connected to a powder supply cylinder for supplying powder toward the circumferential direction of the inner periphery of the powder supply header, and the powder supply header is swung on the inner peripheral wall of the powder supply header. Powder in the upper part of the primary classification room or the lower part of the secondary classification room Air classifier forming the inflow hole to pivot flow into.   The airflow classifier according to claim 1, wherein a plurality of the air nozzles are provided, and the plurality of air nozzles are provided at equal intervals around the outer peripheral wall of the primary classification chamber.   The airflow classifier according to claim 1 or 2, wherein a conical or cylindrical center core is provided at the center of the top wall of the secondary classification chamber.   The airflow classifier according to claim 3, wherein an exhaust port is formed on a central axis of the center core.   The airflow classifier according to any one of claims 1 to 4, wherein a height dimension of the primary classification chamber or the secondary classification chamber is adjustable.   The powder supply cylinder is provided at equal intervals in the circumferential direction of the annular powder supply header, and the powder supply apparatus is connected to the powder supply cylinder, and the powder supply apparatus is connected to the powder supply cylinder from the air injection nozzle. 6. A structure in which a suction force is applied to a lower outlet of a hopper filled with powder by an ejector action of high-pressure air injected into the hopper to supply the powder in the hopper to a powder supply cylinder. The air classifier according to any one of the above.   The airflow classifier according to any one of claims 1 to 6, wherein the secondary classification chamber is divided into a plurality of stages in the vertical direction and has a smaller diameter toward the upper stage side of the secondary classification chamber.   The airflow classifier according to any one of claims 1 to 7, wherein the inflow hole includes an annular slit or a plurality of arc-shaped slits formed at intervals in the circumferential direction.   An air classifier according to any one of claims 1 to 8, a solid-gas separator that separates a solid-gas mixed fluid fed from a fine powder discharge tube of the air classifier into fine powder and air, and the solid gas It consists of a dust collector that collects powder in the air sent from the air outlet of the separator and clarifies the air, and a blower that applies suction to the dust collector or sends high-pressure air to the air nozzle Classification plant.   A pulverizer for pulverizing coarse powder discharged from the outlet is connected to a lower end outlet of the casing of the airflow classifier, and a powder outlet of the pulverizer and a powder supply cylinder are connected by a circulation path. 9. The classification plant according to 9.   A second airflow classifier for classifying fine powder fed from the powder outlet of the solid-gas separator into a fine powder and ultrafine powder, and a solid-gas mixture fed from the second airflow classifier A second solid-gas separator that separates the fluid into ultrafine powder and air, and a second dust collector that collects the powder in the air fed from the solid-gas separator and clarifies the air are provided. The classification plant according to claim 9.   A classification chamber is formed on a classification plate provided in the casing, and the powder is swirled at high speed in the classification chamber and centrifuged into coarse powder and fine powder, and the coarse powder is formed on the outer periphery of the classification plate. Crushing coarse powder discharged from the lower end of the casing of the airflow classifier and the airflow classifier for primary treatment that discharges downward from the powder discharge port and discharges the fine powder from the fine powder discharge cylinder connected to the center of the classification plate A pulverizer for circulating the pulverized powder into the classification chamber of the airflow classifier, a solid-gas separator for separating the solid-gas mixed fluid sent from the fine powder discharge cylinder into fine powder and air, The fine powder fed from the solid-gas separator is classified, and the secondary airflow classifier according to any one of claims 1 to 8, and the fine powder discharge tube of the secondary airflow classifier The solid-liquid mixed fluid that is fed is separated into air and ultrafine powder. A separator, a dust collector that collects powder in the air fed from the air outlet of the solid-gas separator and clarifies the air, and applies a suction force to the dust collector or a high pressure to the air nozzle A classification plant consisting of a blower that feeds air.

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