JPH10174896A - Fine powder producing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly start or suspend the operation of the device and to improve the production efficiency of the device by providing a nozzle below an accelerating tube to blow compressed air upward and furnishing a classification rotor in a crushing chamber above a collision plate. SOLUTION: When the fine powder of toner, abrasive, etc., is produced, the powder is accelerated in an accelerating tube 3 by the compressed air 2 from a nozzle 1, collided with a collision plate 5 set in a crushing chamber 4 and crushed. A classification rotor 6 is provided at the upper part of the crushing chamber 4 to classify the crushed fine powder, and the fine powder smaller than the specified grain diameter is discharged. Meanwhile, the coarse powder having a larger grain diameter is separated by the rotor 6 and returned to the nozzle 1 through a return passage 7. A practically conical receiving plane 8 is provided at the lower part of the return passage 7, and the lower end of the powder receiving plane 8 functions as a powder feed port 9 to surround the periphery of the nozzle 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accelerating powder in an accelerating tube by compressed air blown out from a nozzle, and impinging and pulverizing the powder on an impingement plate provided in a pulverizing chamber communicating with the accelerating tube to produce fine powder. It relates to an apparatus for producing fine powder.

[0002]

2. Description of the Related Art Conventionally, this type of fine powder production apparatus has
For example, there is one disclosed in JP-A-6-154639. In the conventional fine-powder manufacturing apparatus, a pulverizing unit, that is, a nozzle for injecting compressed air, an accelerating tube having a powder supply unit, and a powder mixed in the compressed air at high speed collide at the lowest position. At the uppermost position, the crushed fine powder is transported to the next collection step, and the uncrushed coarse powder is classified and the raw material is crushed and crushed again. An airflow classifier to be conveyed to the hopper is provided, and in particular, of the intermediate portion between the pulverizing section and the airflow classifier, a portion from the pulverizing section to the airflow classifier is provided with a tubular circulation path. is there.

[0003]

However, according to the above-mentioned conventional fine powder production apparatus, there are the following problems. For example, when the operation of the fine powder manufacturing apparatus is interrupted, the powder circulating in the apparatus stays in a circulation path or the like. Since this staying position corresponds to an intermediate position between the pulverizing section and the airflow classifier, among the staying powders, in addition to large-sized powders that have not yet been sufficiently pulverized, pulverization has already been completed. Powder having a small particle size. Therefore, particularly due to the presence of fine powder, the retained powder is likely to be clogged in the circulation path, and when starting up the fine powder production device again,
If the compressed air is supplied somewhat more, the accumulated powder may not be recirculated in some cases. In addition, the retention position of the powder is considered to be biased to the vicinity of the lowermost position of the fine powder manufacturing apparatus. In this case, in order to transport the powder once retained to the position of the upper airflow classifier having a height difference, ,
Since it is necessary to feed the carrier air separately from the compressed air, there is a problem that power consumption is increased. As is evident from the above, in the conventional fine powder production equipment, once the operation of the fine powder production equipment is interrupted, it is difficult to resume normal operation immediately thereafter, and in some cases, the circulation path There is still room for improvement in that the operating efficiency of the entire fine powder production apparatus is impaired, such as the necessity of cleaning the entire interior and the large power consumption for the air for conveyance.

An object of the present invention is to provide a fine powder production apparatus which can solve the above-mentioned drawbacks of the prior art and can quickly start and stop the operation of the apparatus and improve the production efficiency of fine powder.

[0005]

The features of the present invention for achieving this object will be described with reference to the example shown in FIG.

(Structure 1) In the fine powder producing apparatus of the present invention, a nozzle 1 is provided below an accelerating tube 3 so as to blow out compressed air 2 upward, and the inside of a pulverizing chamber 4 is provided. The classifying rotor 6 provided above the collision plate 5 and the coarse powder selected by the classifying rotor 6 are provided so as to surround the pulverizing chamber 4 and the accelerating tube 3 so as to return to the nozzle 1 again. The lower end of the return passage 7 and the powder receiving surface 8 provided below the return passage 7 is moved to a position near the outer periphery of the nozzle 1 and near the lower end of the acceleration tube 3. It is characterized in that it has a powder supply port 9 provided so as to surround the outer peripheral portion of the nozzle 1 by being extended. (Function and Effect) The fine powder production apparatus according to the present invention has a configuration in which the powder is crushed and crushed by the upward compressed air, and the unpulverized powder is returned to the nozzle side again through the return flow path. It is possible to carry out the powder only by the compressed air injected from the nozzle without separately providing a powder circulation path or a circulation blower for circulating the pulverized powder, and to have a simple device configuration. Can be. Also, the unpulverized powder that has circulated in the powder circulation path is deposited on the powder receiving surface, but the powder receiving surface is inclined downward toward the nozzle. It is maintained in a state where it is easy to slide to the side. Therefore, even if the fine-powder manufacturing apparatus is temporarily interrupted, when the operation is started again, if the powder located at the lower end of the deposited powder is scattered upward by the high-pressure air from the nozzle, the upward The powder deposited on the nozzle slides toward the nozzle and is sequentially attracted to the high-pressure air to start recirculation. Furthermore, since the powder receiving surface is located on the downstream side of the classifier, the powder deposited on the powder receiving surface does not include finely ground powder in principle, and has a large particle size. Contains only ground powder. For this reason, the powder deposited on the powder receiving surface becomes difficult to agglomerate, and the powder deposited on the lower end of the powder receiving surface is scattered by the high-pressure air when the fine powder manufacturing apparatus is restarted. The powder deposited above can easily slide on the powder receiving surface. As described above, according to the fine powder production apparatus of the present invention, even if powder remains in the fine powder production apparatus at the time of restarting operation, it is relatively easy to recirculate the powder, and In this case, the necessity of cleaning the apparatus at the time can be reduced, so that the operation efficiency of the fine powder production apparatus can be improved, and the production efficiency of the fine powder can be improved.

(Structure 2) As described in claim 2, the fine powder production apparatus of the present invention is provided with a plurality of projecting members 14 protruding into the return flow path 7 at a plurality of positions on the powder receiving surface 8. You can also. (Operation / Effect) By providing the projecting member as in this configuration, when the powder slides down the powder receiving surface, the lower side of the projecting member becomes a shadow of the flow of the powder. Accumulation of the body can be suppressed. As a result, the space between the powder receiving surface and the lower end of the accelerating tube is not completely blocked by the accumulated powder, and a passage for the circulating airflow can always be secured. Therefore, even if the amount of the powder material to be charged into the fine powder production apparatus is somewhat increased, the operation state of the apparatus can be normally maintained.

(Structure 3) In the fine-powder manufacturing apparatus according to the present invention, an auxiliary air supply port 16 for supplying auxiliary air 15 to the inside of the acceleration tube 3 is provided at an outer peripheral portion of the nozzle 1. At the lower end of the powder receiving surface 8 and the auxiliary air 15 is supplied from an auxiliary air supply port 16 via an auxiliary air chamber 17 provided with a pressure detector 18 capable of measuring the internal pressure. You can also. (Operation / Effect) In this configuration, the auxiliary air is temporarily passed through the auxiliary air chamber before the auxiliary air is supplied from the auxiliary air supply port, and the auxiliary air chamber is caused by a change in the circulation state of the circulating airflow. To monitor the pressure fluctuation of As a result, when the pressure in the auxiliary air chamber is constant, it is determined that the supply of the auxiliary air can be performed smoothly, that is, the circulation state of the powder in the fine powder manufacturing apparatus is determined to be steady, and the Do the input as usual. Conversely, when the pressure in the auxiliary air chamber rises, the supply of auxiliary air cannot be performed smoothly, that is, the amount of circulating powder is excessive, and the auxiliary air supply port is closed or closed. It is determined that the state is close, and the charging of the powder material is reduced or stopped until the pressure in the auxiliary air chamber decreases to a steady value. As described above, according to this configuration, it is possible to monitor the circulation state of the powder circulating inside the fine powder production apparatus, and it is possible to easily control the charging of the powder material.

[0009] In the description of the means for solving the above problems, reference is made to the drawings and, in order to facilitate comparison with the drawings, the reference numerals are used. However, the present invention is limited to the configuration shown in the accompanying drawings. Not something.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

(Outline of Apparatus) FIG. 1 shows an outline of a fine powder production apparatus S of the present invention. The fine-powder manufacturing apparatus S of the present invention is applicable to various fine powders such as a toner, a photosensitive material, an abrasive, a pigment, and a mineral powder. Then, the powder is accelerated, and the powder is collided and pulverized with a collision plate 5 provided in a pulverizing chamber 4 communicating with the accelerating tube 3 to obtain fine powder. In the fine powder production apparatus S, the nozzle 1 is provided below the accelerating tube 3 and blows out the compressed air 2 and the powder upward. A classifying rotor 6 for classifying the crushed fine powder is provided in an upper part of the crushing chamber 4.
Here, fine powder having a predetermined particle size or less is taken out. on the other hand,
The coarse powder having an excessively large particle size during the pulverization is sorted out by the classifying rotor 6 and returned to the nozzle 1 again through the return flow path 7 provided so as to surround the pulverization chamber 4 and the acceleration tube 3. A substantially conical powder receiving surface 8 is provided below the return channel 7. The powder receiving surface 8 has a configuration in which its lower end extends to a position near the outer peripheral portion of the nozzle 1 and near the lower end of the acceleration tube 3. That is, the lower end of the powder receiving surface 8 is provided with the powder supply port 9 provided in a state surrounding the outer peripheral portion of the nozzle 1.
As a function. According to the fine powder production apparatus S of the present invention, it is possible to introduce a powder material having a particle size of about 0.5 to 4.5 mm and produce a fine powder of about several microns to several tens of microns.

The fine-powder manufacturing apparatus S according to the present invention has a configuration in which the powder is crushed and crushed by the upward compressed air 2 and the unpulverized powder is returned to the nozzle 1 again through the return channel 7. Particularly, the powder can be conveyed only by the compressed air 2 injected from the nozzle 1 without separately providing a circulation blower or the like for circulating the unmilled powder, and a simple device configuration is provided. Can be. Further, the powder receiving surface 8
The powder in the pulverization process deposited on the surface is broken down from the lower part by the circulating airflow 10 in the apparatus caused by the compressed air 2 injected from the nozzle 1, and the powder is deposited on the powder receiving surface 8.
To prevent stagnation in the lower part of the vehicle. Therefore, the return flow path 7
Inconveniences such as clogging are unlikely to occur, and the circulating state of the powder can be favorably maintained. Hereinafter, the details of the fine powder production apparatus S according to the present invention will be described.

(Nozzle) A nozzle 1 for injecting compressed air 2 into the accelerating pipe 3 is provided upward at the lowermost end of the fine powder production apparatus S according to the present invention. Compressed air 2 of about ^{3 to} 8 Nm ³ / min is injected from the nozzle 1. The outer peripheral surface of the nozzle 1 has a substantially conical shape whose diameter increases toward the lower side. By this shape, the angle change when the direction of the circulating airflow 10 descending on the powder receiving surface 8 is directed again to the tip of the nozzle 1 is reduced, and the circulating airflow 10 descending the return flow path 7 is again reduced. It can be easily turned to the nozzle 1 side. As a result, as will be described later, the powder that has been pulverized on the powder receiving surface 8 and is being pulverized is circulated through the circulating air flow 1 in the apparatus.
0 makes it easier to convey the compressed air 2 again into the injection area. Note that the number of nozzles 1 may be one as in the present embodiment or a plurality.

(Accelerator tube / collision plate) The pulverized powder mixed into the compressed air 2 injected from the nozzle is accelerated inside the accelerating tube 3, and is pulverized provided in connection with the accelerating tube 3. It is hit at a predetermined speed against a collision plate 5 provided inside the chamber 4. The internal pressure of the crushing chamber 4 is set to about −300 mmH _{2 for} the purpose of maintaining the speed of the compressed air 2 at a high speed.
O is set to a low pressure. In order to set the inside of the fine-powder manufacturing apparatus S to a low pressure, the air in the fine-powder manufacturing apparatus S is sucked by a blower separately provided to take out the pulverized fine powder. The collision plate 5 is supported inside the crushing chamber 4 by a plurality of support members 12 provided on a side wall 11 of the crushing chamber 4 so as to be located on the axis of injection of the compressed air 2. The powder material colliding with the lower surface 5a of the collision plate 5 from below is subjected to the first pulverization by the collision. The lower surface 5
a repelled by the lower surface 5a, the compressed air 2
And scatters radially outward with respect to the injection axis. As a result, the powder ejected from the accelerating tube 3 one after another can surely collide with the lower surface 5a of the collision plate 5, and the effect of the first collision grinding can be maximized. Further, the powder after colliding with the lower surface 5a of the collision plate 5,
Thereafter, the powder collides with the side wall 11 of the crushing chamber 4 to perform the second crushing. By these collisions, the powder material is pulverized to a particle size of about several tens of microns. The side wall 11 of the crushing chamber 4
Is provided with a liner 13 made of a wear-resistant material to prevent abrasion due to powder collision.

(Powder Receiving Surface / Protrusion Member) A powder material is mixed into the compressed air 2 from around the nozzle 1. That is, the powder deposited on the powder receiving surface 8 extending to the vicinity of the nozzle 1 is continuously supplied. The powder receiving surface 8 is formed in a substantially conical surface shape, and the powder having a large particle size selected by the classification rotor 6 is deposited on the surface of the powder receiving surface 8. The space above the accumulated powder forms a passage for the circulating airflow 10, and the accumulated powder is again injected into the compressed air 2 from the nozzle 1 together with the circulating airflow 10.

On the powder receiving surface 8, as shown in FIG.
A plurality of projecting members 14 are provided to secure the flow of the circulating airflow 10 passing over the surface of the deposited powder material. By providing the projection member 14, when the powder slides down the powder receiving surface 8, the lower side of the projection member 14 becomes a shadow of the flow of the powder, so that the powder is deposited on the lower side of the projection member 14. Can be suppressed. As a result, the space between the powder receiving surface 8 and the lower end of the accelerating tube 3 is not completely blocked by the accumulated powder, and the passage of the circulating airflow 10 can be always secured. Therefore, even if the amount of the powder material to be charged into the fine powder production device S is somewhat increased, the operation state of the fine powder production device S can be maintained normally. Note that the shape of the projection member 14 is not particularly limited. Although FIG. 2 shows the substantially columnar projection member 14, the cross section may have any shape. Further, the number of the protrusion members 14 is not particularly limited.

According to this configuration, the powder can be supplied from the entire periphery of the nozzle 1, so that the powder can be uniformly mixed with the compressed air 2. As a result, it is possible to reduce the occurrence of a situation in which the powder is concentrated and collides with a specific portion of the lower surface 5a of the collision plate 5, so that the adverse effect caused by the denseness of the injected powder, for example, the powder is concentrated Therefore, it is possible to suppress the occurrence of the inconvenience that the subsequent crushing of the powder cannot be sufficiently performed because the collision of the powder that subsequently collides with the colliding portion is hindered.

(Auxiliary Air) As shown in FIGS. 1 and 2, between the outer peripheral portion of the nozzle 1 and the lower end of the powder receiving surface 8, auxiliary air 15 is supplied from the lower end of the powder receiving surface 8. Accelerator tube 3
An auxiliary air supply port 16 for supplying the inside of the nozzle is provided over the entire circumference of the nozzle 1. The flow rate of the auxiliary air 15 is approximately 1 Nm ³ / min. With this auxiliary air 15, the circulation state of the powder circulating inside the fine powder production device S can be monitored first. That is, before the auxiliary air 15 is supplied from the auxiliary air supply port 16, the auxiliary air 15 is once passed through the auxiliary air chamber 17. Then, the pressure inside the auxiliary air chamber 17 is detected by the pressure detector 1 provided in the auxiliary air chamber 17.
Always monitor by 8. In this case, when the circulation of the powder in the fine powder production apparatus S is in a steady state, the auxiliary air 15 can be supplied to the inside of the acceleration pipe 3 without any obstacle, and the pressure in the auxiliary air chamber 17 is constant. Maintained at pressure.
On the other hand, powder accumulates below the powder receiving surface 8,
When the auxiliary air supply port 16 is in a closed state or in a state close to the closed state, an obstacle occurs in the circulation of the powder,
The auxiliary air 15 is hardly discharged from the auxiliary air supply port 16 and the pressure in the auxiliary air chamber 17 increases. In this case, the input of the powder material from the material input port 19 is reduced or stopped until the amount of circulating powder in the fine powder production device S is reduced.
When the total amount of the circulating powder decreases, the amount of powder deposited near the auxiliary air supply port 16 also decreases. The pressure in the air chamber 17 decreases. At that time, a new powder material is additionally charged from the material input port 19.

(Classification rotor) The classification rotor 6 is shown in FIG.
Is provided at the top of the crushing chamber 4 as shown in FIG.
Among the fine powder pulverized by the above, only the powder having a predetermined particle size or less is classified and taken out to the takeout path 20 side. In this embodiment, as shown in FIG.
A so-called vertical classifying rotor 6 that rotates around a circle is used. The classifying rotor 6 can rotate up to about 7000 rpm. FIGS. 3A and 3B are cross-sectional views of two typical classifying rotors 6 applicable to the fine powder manufacturing apparatus S of the present application when viewed from above. The classification rotor 6 shown in FIG. 3A has a plurality of blades 22a extending in the radial direction Y with respect to the rotation axis X. In this case, the same classification performance is exhibited regardless of whether the rotation direction Z of the classification rotor 6 is clockwise or counterclockwise. On the other hand, the classification rotor 6 shown in FIG. 3B has a plurality of blades 22b inclined with respect to the radial direction Y of the rotation axis X. In this case, in order to classify into smaller particles,
The rotation direction Z of the classifying rotor 6 is preferably set to be counterclockwise as viewed from above. That is, the air in the crushing chamber 4 is sucked by the blower to the takeout path 20 side, but the air in the crushing chamber 4 is blown by the blades 22 a and 22 of the classification rotor 6.
It must pass between b. At this time, if the blade 22b of the classifying rotor 6 is provided with a receding angle, it acts so as to prevent the flow of the fine powder that is going to pass from the crushing chamber 4 to the extraction path 20 side, and crushes the powder to a predetermined particle size or less. This is because it is possible to allow only the fine powder that has been passed through. As a result, FIG.
The classifying rotor 6 shown in (b) is different from the classifying rotor 6 shown in FIG. 3A in conditions other than the angles of the blades 22a and 22b, for example, the rotation speed or the blades 22a and 22b.
If the intervals between the layers 22b are the same, fine powder having a smaller diameter can be classified. By using the classification rotor 6, fine powder having a particle size of several microns to several tens microns can be classified. The type of the classification rotor 6 is not limited to the vertical type as described above, but may be a so-called horizontal type that rotates around a horizontal axis. The fine powder classified by the classification rotor 6 is then taken out of the discharge path 20.
Through the bag filter, where it is taken out as a product.

Further, as shown in FIG.
A rinsing air supply port 23 for sealing a gap between the two is provided between the upper part of the apparatus and the main body of the fine powder production apparatus S. The rinsing air 24 supplied from the rinsing air supply port 23 is ejected in an annular shape at a substantially central position between the inner diameter and the outer diameter of the upper surface 6a of the classifying rotor 6 having a substantially annular shape. . And classification rotor 6
A part of the rinsing air 24 blown to the upper surface 6a is discharged to the crushing chamber 4 side, and the remaining portion is
Is discharged to the side. By the rinsing air 24,
This prevents the powder circulating in the crushing chamber 4 from being crushed during the crushing and leaking to the takeout path 20 side without passing through the classifying rotor 6.

(Embodiment) FIG. 4 shows an embodiment in which fine powder of an acrylic-styrene resin is manufactured using the fine powder manufacturing apparatus S of the present invention. In this example, 6 kgf / m ²
2 shows the efficiency of producing fine powder when the compressed air 2 is injected from the nozzle 1 at a flow rate of 8 Nm ³ / min. For example, if the target powder particle size is 6 microns, the production capacity of fine powder was about 16 kg / hr. When the target particle size was 10 microns, the production capacity was about 40 kg / hr.
The supply amount of the auxiliary air 15 in the above embodiment is 1 Nm.
³ / min, and the supply amount of the rinsing air 24 is 1
~ 1.5 Nm ³ / min, suction volume by blower is about 1
It was 0 Nm ³ / min.

[Another Embodiment] In the above embodiment,
The configuration of the fine powder manufacturing apparatus S alone is shown, but FIG. 5 shows an example of a fine powder manufacturing system including the fine powder manufacturing apparatus S. First, the powder material coarsely crushed in advance is supplied to the medium crusher 26 by the supply feeder 25. The powder material pulverized by the medium pulverizer 26 is passed through a first collector 27, where the powder material having a particle size larger than a predetermined particle size is selected.
As the first collector 27, for example, a cyclone collector can be used. The powder material sorted by the first collector 27 and having a uniform particle size is thereafter supplied to the fine powder production apparatus S according to the present invention. As described above, the pulverization of the powder material is performed in the fine powder production apparatus S. The pulverized powder material is passed through the classification rotor 6 to the second material.
It is passed through the collector 28 and the fine powder classifier 29, and the finely divided fine powder having a predetermined particle size or less is sorted and collected twice. The coarse powder selected while homogenizing the particle size through the second collector 28 and the fine particle classifier 29 becomes a final product, and the fine powder having a small particle size that is not selected is collected by the bag filter 30 and then collected. You. The configuration of these devices is, for example, a classification rotor similar to the classification rotor 6 used in the fine powder production device S of the present invention, and the second collector 28 is a cyclone type collection device, and the fine powder classifier 29 is used in the fine powder production device S of the present invention. It can be configured using.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a fine powder production apparatus according to the present invention.

FIG. 2 is a perspective view showing the vicinity of a nozzle.

FIG. 3 is a cross-sectional view of a classification rotor.

FIG. 4 is a graph showing an example of a particle size distribution of fine powder obtained by the fine powder manufacturing apparatus of the present invention.

FIG. 5 is a schematic diagram of a fine powder production system configured using the fine powder production apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Compressed air 3 Acceleration tube 4 Crushing chamber 5 Impact plate 6 Classification rotor 7 Return flow path 8 Powder receiving surface 9 Powder supply port 14 Protrusion member 15 Auxiliary air 16 Auxiliary air supply port 17 Auxiliary air chamber 18 Pressure detector

Claims (3)

[Claims] 1. A fine powder producing apparatus for accelerating powder in an accelerating tube by compressed air blown out from a nozzle and impinging and pulverizing the powder against an impinging plate provided in a pulverizing chamber communicating with the accelerating tube to obtain fine powder. The nozzle is provided below the accelerating tube so as to blow upward compressed air, and the classifying rotor provided inside the pulverizing chamber and above the collision plate, and the coarse powder selected by the classifying rotor is In order to return to the nozzle side again, a return flow path provided so as to surround the pulverizing chamber and the accelerating tube, and a lower end portion of a powder receiving surface provided below the return flow path, the outer periphery of the nozzle. A powder supply port which is provided in the vicinity of the nozzle and near the lower end of the accelerating tube so as to surround the outer periphery of the nozzle. 2. The fine powder production apparatus according to claim 1, wherein projection members are provided at a plurality of positions on the powder receiving surface so as to project into the return flow path. 3. An auxiliary air supply port for supplying auxiliary air to the inside of the accelerating tube is provided at an outer peripheral portion of the nozzle and at a lower end of the powder receiving surface. 3. The fine powder production apparatus according to claim 1, wherein the apparatus is configured to be supplied from the auxiliary air supply port via an auxiliary air chamber provided with a pressure detector capable of measuring pressure. 4.