JP4498550B2 - Airflow classifier - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention classifies, for example, a powder raw material such as a toner for developing an electrostatic image into a powder having a predetermined particle diameter based on a difference between an inertial force and a centrifugal force corresponding to the powder diameter of each particle. The present invention relates to an apparatus, and more particularly to an airflow classifier that automatically adjusts an edge portion of a classification edge to an allowable range to improve classification accuracy.
[0002]
[Prior art]
The toner or colored resin powder used for image formation by electrophotography is currently mainly melt-kneaded a mixture containing at least a binder resin and a colorant, and the melt-kneaded product is cooled to be a cooled product. It is manufactured by pulverizing the obtained cooling product and further classifying the pulverized product. On the other hand, various airflow classifiers and airflow classification methods have been proposed for powder classification. Among them, there are classifiers using rotating blades and classifiers having no moving parts. Among these, there are a fixed-wall centrifugal classifier and an inertial force classifier as classifiers having no moving parts. The present invention is an inertial force classifier, and the type shown in FIG. 5 is conventionally used as this type of airflow classifier. For example, an elbow jet classifier manufactured by Nippon Steel Mining Co., Ltd. can be used.
[0003]
FIG. 5 is a cross-sectional view showing an internal structure of a main part of a conventional airflow classifier 200 using an inertial force. On the surface of the side plate 101, an upper right wall 122, an upper left wall 124, a lower right wall 123, and a lower left wall 125 are formed to protrude, and between the upper right wall 122 and the lower right wall 123, a Coanda block is formed. 126 protrudes and is arrange | positioned. An intake path 131 branched by an intake edge 119 is formed between the upper right wall 122 and the upper left wall 124. The inlet edge 119 is pivotally supported at the base end portion by an upper cover 127 provided between the upper right side plate 122 and the upper left side plate 124. Further, the lower right wall 123 and the lower left wall 125 are provided with classification edges 117 and 118 whose base end portions are pivotally supported by them. A powder material supply pipe 116 for introducing a powder material is inserted between the upper surface of the Coanda block 126 and the upper right wall 122. In addition, inlet pipes 114 and 115 having gas introduction adjusting means 120 and 121 are arranged in communication with the two inlet passages 131. The intake pipes 114 and 115 are provided with static pressure meters 128 and 129 for detecting the pressure of the airflow.
[0004]
The classification chamber 130 is formed at a position where the arcuate portion of the tip of the Coanda block 126, the edge portion of the tip of the classification edges 117 and 118, and the edge portion of the tip of the air inlet edge 119 are gathered close to each other. In addition, the classification chamber 130 communicates with the inlet 131 and the tip of the raw material supply pipe 116. Further, the classification chamber 130 communicates with the first classification path 111, the second classification path 112, and the third classification path 113. These classification paths 111, 112, and 113 are provided between the upper left plate 124 and the classification edge 118, between the classification edge 118 and the classification edge 117, and between the classification edge 117 and the lower surface of the Coanda block 126, respectively. It is formed. With the above structure, the airflow from the inlet passage 131 and the powder raw material from the powder raw material supply pipe 116 are mixed in the classification chamber 130, and the curved airflow is generated by the inertia force based on the particle size of the powder raw material or the Coanda effect. The powder raw material is classified into the first to third classification paths 111, 112, and 113 by the centrifugal force.
[0005]
[Problems to be solved by the invention]
The powder raw material is desirably classified with high accuracy for each particle size. However, the positioning accuracy of the edge portions of the edge portions of the classification edges 117 and 118 is mentioned as one that greatly affects the classification accuracy. . Further, the position and shape of the arcuate portion of the tip of the Coanda block 126, the position accuracy of the edge portion of the tip of the intake air edge 119, the flow rate and pressure of the incoming airflow, and the like can be mentioned. Among these, the positioning accuracy of the edge portions of the classification edges 117 and 118 is particularly high. However, there is a problem that the edge portions of the classification edges 117 and 118 do not fall within a predetermined allowable range due to a slight play of each drive transmission mechanism of the airflow classifier 200 or insufficient strength. The position of this edge part has a large effect on the streamline of the air flow divided by this edge part even if the amount of deviation is small, and the streamline is disturbed, and the particle size distribution of the classified product changes. There is.
[0006]
The present invention solves the above problems, and provides an airflow classifier that can reduce the variation in the particle size distribution of classified products and can improve the accuracy of the particle size distribution. With the goal.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the airflow classifier according to claim 1 includes a front side plate and a rear side plate disposed opposite to the front side plate with an appropriate interval. Forming an air inlet path for introducing an air flow into the sealed space, a powder raw material supply path, and a classification path for classifying the powder raw material, and classifying the powder raw material into a plurality of types having different particle sizes. An airflow classifier for classifying into raw materials, wherein a classification chamber at the center of the sealed space serving as a classification point is a Coanda block projecting with an arc-shaped tip toward the classification chamber, and toward the classification chamber. And a plurality of classification edges whose base ends are rotatably supported by the front and rear side plates, and an inlet edge that divides the inlet passage by protruding the edge portions toward the classification chamber The classification path faces the classification chamber. A side wall, wherein a plurality of classifying edges, a plurality of formed between each of the Coanda block, the rotational axis of the classification proximal end of the classification edge to be positioned in a predetermined allowable range edge portion of the edge Is provided with a driving means, engages a position detecting means for detecting the rotation angle of the rotary shaft and sets the edge portion within a predetermined allowable range, and the classification is also performed during the classification of the powder raw material. It is characterized by edge position control. As a result, the tip of the classification edge is always set within an allowable range, and high-precision classification is possible, and classification powder having a high-precision particle size distribution can be generated efficiently and stably. In the prior art, it was necessary to interrupt the classification work to adjust the edge portion of the classification edge and remove the front side plate, etc., but in the present invention, the removal is unnecessary, and the edge portion can be adjusted even during classification. . Thereby, efficiency can be improved.
[0010]
The airflow classifier according to claim 2 is characterized in that a gas introduction adjusting means is disposed in the inlet passage, and the driving means is a stepping motor. By using a stepping motor, the classification edge can be driven with high accuracy and smoothness and at a relatively low cost.
[0011]
The airflow classifier according to claim 3 is characterized in that the position detecting means is a potentiometer. By using the potentiometer, it is possible to improve the positioning detection accuracy of the edge portion of the classification edge, and it is possible to classify with high accuracy and to implement at a relatively low cost.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an airflow classifier according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing a structure of a main part (apparatus main body) of an airflow classifier 100 according to the present embodiment, FIG. 2 is an exploded perspective view showing almost all components of the airflow classifier 100, and FIG. It is a perspective view which shows the structure of the principal part similarly to FIG.
[0013]
The airflow classifier 100 is sandwiched between the rear side plate 2 shown in FIG. 2 and the front side plate 1 shown in FIG. 3 arranged in opposition to each other and forms the classification chamber 30 and the like. The airflow classifier main body 100, the rotating shafts 36a and 36b of the classifying edges 5 and 6 of the airflow classifier main body 100a, and the stepping motor 31a, which is one of driving means connected to the rotating shafts 36a and 36b, 31b, and potentiometers 43a, 43b and the like that are connected and engaged with the rotary shafts 36a, 36b.
[0014]
First, the airflow classifier body 100a will be described with reference to FIGS. On the surface of the rear side wall 2, an upper right side wall 19, an upper left side wall 10, a lower right side wall 8, a lower left side wall 9 and a Coanda block 4 are fixed in a protruding state. On the surface of the rear side wall 2 between the upper right side wall 19 and the upper left side wall 10, an upper cover 23 is similarly projected and fixed.
[0015]
The upper cover 23 is pivotally supported by the proximal end portion of the inlet edge 7, and the inlet edge 7 divides the inlet path 32 into a first inlet path 32 a and a second inlet path 32 b. The lower right wall 8 and the lower left wall 9 are connected to classifying edges 5 and 6 whose base ends are pivotally supported by these. Further, the powder raw material supply pipe 3 is inserted between the upper right side wall 19 and the upper surface of the Coanda block 4. In addition, an elliptical arcuate portion 4 a is formed at the tip of the Coanda block 4. In addition, edge portions 5 a and 6 a are formed at the tips of the classification edges 5 and 6, and an edge portion 7 a is also formed at the tip of the air inlet edge 7.
[0016]
The classification chamber 30 is formed at a portion where the edge portions 5 a and 6 a of the classification edges 5 and 6, the arc-shaped portion 4 a of the Coanda block 4, and the edge portion 7 a of the inlet edge 7 are gathered. The classification chamber 30 communicates with the first to third classification paths 11, 12, and 13. The first classification path 11 is formed between the lower surface side of the upper left side wall 10 and the classification edge 6 and the lower left side wall 9. The second classifying path 12 is formed between the classifying edges 5 and 6 and the lower right side wall 8 and the lower left side wall 9. The third classification path 13 is formed between the classification edge 5, the lower right side wall 8, and the lower surface side of the Coanda block 4.
[0017]
The inlet pipes 14 and 15 are connected to the first inlet path 32 a and the second inlet path 32 b of the inlet path 32. Further, the inlet pipes 14 and 15 are provided with gas introduction adjusting means 20 and 21 and static pressure meters 28 and 29 for detecting the pressure of the introduced gas, respectively.
[0018]
As shown in FIG. 4, the powder raw material is introduced into the powder raw material supply pipe 3 from the quantitative feeder 18 through the vibration feeder 17. The powder raw material supply pipe 3 is supplied with air for ejecting the powder raw material, and the supply amount of this air is controlled by a valve 16.
[0019]
There are various powder raw materials, and examples thereof include toner or colored resin powder used for image formation by electrophotography. This toner or colored resin powder mainly comprises a mixture obtained by melt-kneading a mixture of at least a binder resin and a colorant, cooling the melt-kneaded product, and pulverizing the cooled product.
[0020]
The classification chamber 30 and the like of the airflow classifier main body 100a having the above structure are closed and sealed by the front side plate 1 as shown in FIG. Further, the collection cyclones 22a, 22b, and 22c are connected to the first to third classification paths 11, 12, and 13 of the airflow classifier main body 100a through the first to third pipes 11a, 12a, and 13a, respectively. Is done.
[0021]
As described above, the classification chamber 30 is divided into a plurality of classification paths 11, 12, and 13. The classification accuracy depends on the positions of the edge portions 5a and 6a of the classification edges 5 and 6, the shape of the arcuate portion 4a of the Coanda block, It is determined by the position, the position of the edge portion 7a of the inlet edge 7, and the like, and also determined by the flow rate of the classification air flow and the ejection speed of the powder raw material from the raw material supply pipe 3.
[0022]
As shown in FIG. 2, rotating shafts 36 a and 36 b pivoted by the front side plate 1 and the rear side plate 2 are connected to the base end portions of the classification edges 5 and 6. The rotary shafts 36a and 36b are connected to the stepping motors 31a and 31b through various connecting means (detailed explanation is omitted) shown in FIG. The rotary shafts 36a and 36b are connected to potentiometers 43a and 43b via pulleys 35a and 35b, belts 51a and 51b, and pulleys 49a and 49b. The stepping motors 31a and 31b rotate the rotation shafts 36a and 36b to a desired angle, and the potentiometers 43a and 43b detect the positions of the edge portions 5a and 6a of the classification edges 5 and 6. is there.
[0023]
In the present invention, in particular, the positions of the edge portions 5a and 6a of the classification edges 5 and 6 are always within the allowable range. This allowable range is determined in advance according to the properties of the powder raw material, and this position is detected by the potentiometers 43a and 43b. Therefore, when the positions of the edge portions 5a and 6a of the classification edges 5 and 6 are deviated due to the displacement of each element during classification work, the deviation from the normal position is automatically detected by the potentiometers 43a and 43b. Since this detection information is transmitted to the stepping motors 31a and 31b, it is easy to always set the edge portions 5a and 6a of the classification edges 5 and 6 to positions within an allowable range by driving the stepping motors 31a and 31b. it can.
[0024]
Next, the classification action of the powder raw material by the airflow classifier 100 of the present invention will be described. Although any powder raw material may be used as described above, it is particularly effective for classification of toner or colored resin powder used for image formation by electrophotography. When such a powder raw material for toner production is classified by a conventional classifier, it is necessary to accurately limit and stabilize the various classification conditions in order to obtain a particle size distribution of the intermediate product. is there. In addition, the classification point tends to deviate from the appropriate range due to minute changes in the classification room. In this case, the required particle size distribution is difficult to obtain, and the classification efficiency may be greatly reduced. Arise. In order to obtain a product with a constant quality, it is necessary to operate stably, and the airflow classifier 100 of the present invention is effective for this purpose.
[0025]
As shown in FIG. 4, the powder raw material is introduced from the quantitative feeder 18, and sent in a state where the powder raw material is pressurized into the powder raw material supply pipe 3 through the vibration feeder 17, and reaches the classification chamber 30. The On the other hand, an air flow such as air is introduced from the inlet pipes 14 and 15 into the inlet passages 32 a and 32 b with the supply amount and pressure adjusted by the gas introduction adjusting means 20 and 21 and the static pressure gauges 28 and 29, and enters the classification chamber 30. It arrives. In the vicinity of the classification chamber 30, the edge portions 5 a and 6 a and the edge portion 7 a are arranged with their positions adjusted to form classification points. When the edge portions 5a and 6a of the classification edges 5 and 6 have a deviation amount of about ± 0.3 mm from the normal position, the powder raw material is classified with high accuracy from the classification point, and the first to third classification paths 11, Particles corresponding to the particle size are classified and sent to 12 and 13, respectively. As shown in FIG. 4, the classified particles are introduced into the collection cyclones 22a, 22b, and 22c through the first pipe 11a, the second pipe 12a, and the third pipe 13a and collected as fine powder.
[0026]
1. According to the airflow classifier of claim 1 of the present invention, the position of the edge portion of the classification edge can be automatically set, and the variation of the classification point can be suppressed, so that the specific gravity and classification of various powder raw materials can be suppressed. Accurate classification points corresponding to gas conditions can be obtained, particles with a high precision (sharp) particle size distribution can be obtained with high classification accuracy, and classified particles can be produced continuously. Further, since the edge portion of the classification edge can be adjusted even during the classification work, the work efficiency can be improved . 2. According to the airflow classifier of claim 2 of the present invention, since the stepping motor is adopted as the driving means, the edge portion can be adjusted with high accuracy, and it can be obtained relatively easily and the cost of the apparatus can be reduced. 3. According to the airflow classifying device of claim 3 of the present invention, since the potentiometer is employed, the positioning accuracy of the edge portion can be detected with high accuracy and the device cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the structure of the main part of an airflow classifier according to the present invention.
FIG. 2 is an exploded perspective view showing almost the entire structure of components of the airflow classifier of the present invention.
FIG. 3 is a perspective view showing the structure of the main part of the airflow classifier of the present invention.
FIG. 4 is a configuration diagram for explaining the classification action by the airflow classifier of the present invention.
FIG. 5 is a sectional view showing a structure of a main part of a conventional airflow classifier.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Front side plate 2 Back side plate 3 Powder raw material supply pipe 4 Coanda block 4a Arc-shaped part 5 Classification edge 5a Edge part 6 Classification edge 6a Edge part 7 Inlet edge 7a Edge part 8 Lower right wall 9 Lower left wall 10 Upper left wall 11 1st classification path 11a 1st piping 12 2nd classification path 12a 2nd piping 13 3rd classification path 13a 3rd piping 14 Intake pipe 15 Intake pipe 16 Valve 17 Vibrating feeder 18 Fixed quantity feeder 19 Upper right Wall 20 Gas introduction adjusting means 21 Gas introduction adjusting means 22a Collection cyclone 22b Collection cyclone 22c Collection cyclone 23 Upper cover 28 Static pressure gauge 29 Static pressure gauge 30 Classification chamber 31a Stepping motor 31b Stepping motor 32 Inlet path 32a Inlet path 32b Inlet passage 35a Pulley 35b Pulley 36a Rotating shaft 36b Rotating shaft 43a Potentiometer Motor 43b potentiometer 49a pulley 49b pulley 51a belt 51b belt 100 air classifier 100a air classifier body

Claims (3)

An air inlet path for introducing an air flow into a sealed space within the space between the front side plate and the rear side plate disposed opposite to the front side plate with an appropriate gap, a powder raw material supply path, a powder Forming a classification path for classifying body materials, and classifying the powder material into a plurality of types of classification materials having different particle sizes,
The classification chamber at the center of the sealed space that serves as a classification point includes a Coanda block that protrudes by forming an arcuate tip toward the classification chamber, and an edge portion that protrudes toward the classification chamber and the base end side of the classification chamber. A plurality of classification edges that are rotatably supported by the front and rear side plates, and formed at a portion where the inlet edges divide the inlet passage by protruding the edge portion toward the classification chamber ,
A plurality of classification paths are formed between the side wall facing the classification chamber, the plurality of classification edges, and the Coanda block,
In order to position the edge portion of the classification edge within a predetermined allowable range, a drive means is provided on the rotation shaft of the base end portion of the classification edge, and the rotation angle of the rotation shaft is detected and the edge portion is determined in advance. An airflow classifier which engages a position detecting means for setting within the allowable range and controls the position of the classification edge even during the classification operation of the powder raw material. 2. The airflow classifier according to claim 1 , wherein a gas introduction adjusting unit is disposed in the inlet passage, and the driving unit is a stepping motor.   The airflow classifier according to claim 1, wherein the position detection means is a potentiometer.

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