JPS62237978A - Powdered-body sorter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a powder classifier that classifies powder by utilizing the balance between centrifugal force and drag force due to air flow.

(Prior art) Various powder classification methods are known in the past, one of which is
An air classification method is known in which powder particles are classified by applying centrifugal force and drag due to air flow to change the balance point determined from the viscosity and particle size of the particles (for example, Japanese Patent Publication No. 11269/1982).

In this type of air classifier, forced vortex classifiers tend to be used to improve the classification accuracy and classify even small particles, but in recent years, the classification accuracy has been improved and the As the demand for powder classification increases, in order to meet this demand and lower the classification point, it is basically necessary to lower the amount of air and increase the rotational speed of the classification rotor.

However, increasing the rotational speed of the classification rotor to 142 is mechanically difficult, so there is a limit to the upper limit, and the energy consumption required for operation also increases. On the other hand, when the amount of air is reduced, the flow of particles in the classification chamber becomes less smooth and the classification performance deteriorates.

(Objects and Structure of the Invention) The present invention has been made in view of the points mentioned in -1-, and is intended to improve classification accuracy even in high rotation and low air volume regions where a low classification point can be obtained. In order to achieve this purpose, a differential user is provided with a shape that restricts the mixed flow of the classified powder and air flow near the outlet that flows into the casing. be.

(Example) The present invention will be explained below based on the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the powder classifier according to the present invention, and FIG. 2 is a partially cutaway plan view of the classification rotor of the powder classifier shown in FIG. It is.

In the figure, ■ indicates a casing that has a powder inlet 2a connected to a powder supply device (not shown) at the center of the plane and an air inlet 2b at the peripheral side. A disk-shaped classification rotor 4 having a cavity 3 that communicates from the circumference to the lower part of the axis is disposed inside the casing 1, and this classification rotor 4 has a bearing 5. 5 is integrally fixed to one end -F of a rotating shaft 6 mounted vertically. Furthermore, in the cavity 3 of the open peripheral portion of the classification rotor 4, a large number of outer classification blades 7 arranged at equal intervals in the circumferential direction are radially formed as shown in FIG. Inside this outer classification blade 7, a large number of inner classification blades 8 facing the outer classification blade 7 are formed radially in two stages in the radial direction of the classification rotor 4. A desired gap 9 is formed between the inner classification blades 7 and 8, and -1- of the classification rotor 4 facing this gap 9 is formed.
The plate 4a is formed with a sliding ring 1- for introducing powder that communicates with the inside of the cavity 3. Also, by having such a classification blade structure, the outer classification blade 7 and the inner classification blade 8 are A classification chamber 11 (7 and 8) with a wide forced vortex corresponding to the coarse powder side and the fine powder side is configured in the section.

In addition, on the lower surface of the classification rotor 4 facing the classification blades 7.8, a large number of auxiliary blades 12 are arranged radially at equal intervals in the circumferential direction, and when the classification rotor 4 rotates, The auxiliary blades 12 give the air a flow in the rotational direction, and the air is introduced into the classification chamber 11 in a swirling state. Reference numeral 13 denotes a space formed around the outer periphery of the classification rotor 4, and a coarse powder outlet 14 communicating with this space 13 is formed in the casing 1.

Reference numeral 15 indicates the powder inlet 2a formed between the upper plate 4a of the classifying rotor 4 and the lower surface of the upper plate of the casing l, and the classifying rotor 4.
A large number of powder dispersion blades extending from the shaft center to the outer circumferential direction are located on the central side of the rice 4a of the classification rotor 4 located in this space 15. 16 are provided radially, and the top plate 4a of the classification rotor 4 between the radial end of the dispersion vane 16 and the ring-shaped powder introduction port 10 is made flat, and this flat surface and the casing l opposite thereto are Dispersion gap 1 for secondary dispersion of powder between inner surfaces
form 7.

Reference numeral 18 denotes a disc-shaped balance rotor having a cavity 19 that communicates from the circumference to the axial center, almost similar to the classification rotor 4, and this balance rotor 18 is arranged symmetrically with the classification rotor 4. The rotating shaft 6 in the casing l is connected so that the driving part 19 communicates with the cavity part 3 of the classification rotor 4.
In addition, a large number of blades 20 are provided radially within the cavity 19 at the opening periphery of the balance rotor 18, and are further integrally and airtightly attached to the balance rotor 18. Note that a collecting device such as a cyclone or a pack filter (not shown) is connected to the spiral casing 21.

As shown in FIG. 3(A), the spiral casing 21 is provided with a differential user 21a extending inward. The shape of the differential user 21a is shown in Figures 3 (a) and (b).
There are various possibilities as shown in (c) and (d), but all of them extend horizontally or slightly upward from the inner wall of the spiral casing 21 toward the outer wall, and extend between the tip of the differential user 21a and the outer wall. It has a structure that functions to narrow down the air flow containing fine powder particles and make it uniform.

Next, the operation of the classifier according to the present invention configured as described above will be explained.

First, the classification rotor 4 and the balance rotor 18 are rotated at a desired speed by an electric motor (not shown), and the suction action of the balance rotor 18 and the air inlet of negative pressure are applied to the interior of the classifier using a blower (not shown) connected to the outside. The air flowing in from 2b is converted into a flow in the rotational direction by the auxiliary blades 12 and enters the classification chamber 11 from the cavity 14 in a swirling state.
In the classification chamber 11, the classification blades 7.8 create an airflow with the same circumferential speed as that of the classification rotor 4. At the same time, since the classification chamber 11 is of a type in which suction is carried out by the balance rotor 18 and the floor, the air on the circumferential surface of the classification chamber 11 flows in the radial direction. Furthermore, the air that has passed through the balance rotor 18 is blown out into the spiral casing 21 or is narrowed down by the differential user 21a at this time to equalize the flow velocity, thereby improving the classification efficiency. This point will become clear from the experimental results described below. The air flow at this time is shown in Figures 1 and 3.
Indicated by arrows in the figure.

In this state, the powder raw material input from the powder input port 2a rides on the airflow and is almost uniformly distributed in the radial direction about the axial center of the classification rotor 4 while passing between the respective dispersion blades 16. The primary dispersion of the powder is performed. As the classification rotor 4 rotates, the powder coming out from the end of the dispersing blades 16 is radiated in a substantially tangential direction between the dispersing blades 16, and the powder is emitted from the dispersing gap 17.
It is quadratic distributed within. The powder, which has been sufficiently dispersed due to the above action, is supplied to the classification chamber 11 through the ring-shaped powder introduction port 10, where each particle of the powder is affected by the drag force (3πpV, D, ). Among these particles, coarse particles for which the relationship of centrifugal force > drag force is satisfied are transferred to the classification rotor 4.
The powder is blown into a space 13 on the outer periphery of the powder, and is taken out of the classifier through a coarse powder outlet 14 under air sealing using a rotary valve or the like. In addition, fine particles for which the relationship of centrifugal force (drag force) holds is air-transported to the outside of the classifier via the balance rotor 18 and overwound casing 21 while riding on the radial air flow, and collected by a cyclone, bag filter, etc. Collected by machine.

Further, the classification point in the classifier having the configuration described in "2" is adjusted by changing the number of revolutions of the classification rotor 4 or the amount of air passing through the classification chamber 11.

Note that the symbols in the "-" notation are as follows.

D2: Average diameter of particles ρp2 Density of particles vo: Wind speed in the circumferential direction ■, 2 Wind speed in the radial direction R: Radial distance of the classification point End: Viscosity coefficient of air Figure 4 shows the effect of the differential user. The results of the comparative experiments conducted are shown. In the experiment, JIS standard powder 11 was used as the powder.
Seeds (Kanto loam) were supplied at a rate of 1.68 kg per minute per minute, the air amount was 1.0 m'/mi, and the rotation speed of the classification rotor was 9500 rpm.

The figure shows the particle size distribution of coarse powder and fine powder after classification as a frequency distribution.
B is a case where there is no differential user for fine powder, and B is a case where a differential user is provided for fine powder. As can be seen from this figure, by providing the differential user, the peaks of the frequency distribution of fine powder and coarse powder move away from each other, and the overlap between coarse powder and fine powder is reduced compared to the case without the differential user. This means that the classification efficiency is improved.

(Effects of the Invention) As explained below, the present invention provides a differential user shaped to throttle the mixed flow of the classified powder and the air flow near the outlet where the mixed flow flows into the casing. Therefore, the flow rate of the mixed flow is made uniform and the separation efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of a powder classifier according to the present invention;
Figure 2 is a partially cutaway plan view of the powder classifier shown in Figure 1, Figures 3 (a), (b), (8), and (d) are diagrams showing different examples of differential users; The figure is a graph showing the results of a classification experiment conducted using the powder classifier according to the present invention. 1...Casing, 2a...Powder injection port, 2b...
・Air inlet, 4... Classifying rotor, 7, 8... Classifying blades, 16... Distributing blades, 18-... Balance rotor, 19... Cavity part, 21... Casing patent application Person Nisshin Seifun Co., Ltd. Nisshin Engineering Co., Ltd. Agent Patent Attorney Hiroshi Suzuki Figure 1 Figure 2 Shocking Revenge

Claims (1)

[Claims] A classification rotor having an air circulation cavity from the circumference to the axial direction is provided in a casing having a powder inlet in the center of the upper surface and an air inlet around the outer wall, rotatable by a vertical rotation shaft, The powder flows outward in the radial direction due to the balance between the centrifugal force acting on the powder due to the rotation of the classification rotor and the drag force acting on the powder due to the air flow passing through the air circulation cavity in the axial direction. A powder classifier, characterized in that a diffuser is provided in the vicinity of an outlet through which an air flow containing the air flows out into the casing, the shape of which narrows the air flow.