JPS62780Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in air classifiers.

There are various types of air classifiers that classify powder using a powder dispersion plate, classification blades, and swirling upward air current, but here, a cyclone separator will be explained as an example. In FIG. 1, 1 is a classification chamber, 2 is a casing of the classification chamber 1, 3 is a powder supply pipe, 4 is a powder supply port, and 8 is a powder passage at the lower end of the powder supply pipe 3. Further, 6 is a motor with a reducer, 7 is a drive shaft driven by the motor 6, 9 is a dispersion plate 10 fixed to the lower end of the drive shaft 7, is a classification blade fixed on the dispersion plate 9, and 11 is a dust-containing blade. Gas discharge pipe, 12 cyclone, 13 gas discharge port, 14 fine powder discharge port, 15
is a circulation fan, 16 is a circulation gas intake port, 17a,
17b is a vane, 18 is a ring belt, 19 is an outer casing, and 20 is a coarse powder discharge port.

To explain the classification mechanism of the above-mentioned cyclone separator, powder having a certain particle size range, such as powder discharged from a crusher, is supplied into the classifier from the supply port 4, passes through the powder supply pipe 3 and the passage 8, and is transferred to the motor. 6, it falls onto the rotating dispersion plate 9. The powder is dispersed toward the outer wall by the centrifugal force from the dispersion plate 9, and is dispersed in the airflow generated by the circulation fan 15 and rising inside the classification chamber 1. At this time, relatively large particles are
Due to the large centrifugal force, it is blown up to the classification chamber casing 2, collides with it, falls under the action of gravity, and is classified. On the other hand, the remaining particles rise on the updraft and pass through the dispersion plate 9 to the rotating classification blade 10.
The object is struck by the object, receives inertial force and stronger centrifugal force, and moves toward the outer wall. At this time, the drag force exerted on the powder by the swirling upward flow and the centrifugal force exerted on the powder in the direction of the outer wall by the classification blades 10 are balanced, and the powder is classified into fine powder and coarse powder.
1 and is led to a cyclone 12 where it is collected and turned into fine powder. The airflow exits from the gas exhaust pipe 13, passes through the circulation fan 15, and enters the classifier again through the circulation gas intake port 16. Further, the classified coarse powder descends through the casing 2 of the classification chamber 1, further passes through the vanes 17a, 17b and the ring belt 18, and is guided to the coarse powder discharge port 20. At this time, the coarse powder descending through the vane portion is redispersed by the swirling airflow that has passed through the vane, and the fine powder adhering to the coarse particles is blown up again. This makes it possible to reduce the amount of fine powder mixed into coarse powder.

However, in such a classifier that has classification blades with a certain length in the radial direction, the circumferential speed differs depending on the radial position of the classification blade, so the inertial force and centrifugal force that particles are subjected to are Since it varies depending on the radial direction, it is not possible to make the separated particle size constant. Particularly near the attachment part of the classification blade, both the inertial force and the centrifugal force exerted on the particles are small, so that the coarse particles slip through to the fine powder side. Therefore, there was a drawback that the introduction of coarse powder into fine powder was unavoidable to some extent.

The present invention was proposed for the purpose of providing a new classification blade and obtaining an air classifier with high classification efficiency in order to improve the drawbacks of the classification blade. An air classifier characterized in that elongated classification blades and short classification blades are attached alternately, and the short classification blades are formed so that their height decreases outward. This is related to.

Hereinafter, according to the embodiments shown in FIGS. 2 to 4,
The present invention will be explained in detail.

In those figures, 24 is a dispersion plate (a member corresponding to the dispersion plate 9 in FIG. 1), and 21 is a long classifier attached to the periphery of the dispersion plate 24 at equal intervals so as to extend in the radial direction. The blades 22 are short classification blades attached to the peripheral edge of the dispersion plate 24 so as to extend in the radial direction between adjacent long classification blades 21, and the long classification blades 21 and the short classification blades 22 are attached alternately to the peripheral edge of the dispersion plate 24. Further, the height h of each short classification blade 22 is formed to decrease toward the outside. (4th
(See figure) In the figure, 23 is a dispersion plate 24 for the supplied powder.
25 indicates the drive shaft of the distribution plate 24, respectively.

One embodiment of the classification blade of the air classifier of the present invention is constructed as described above, and the main action of the air classifier is almost the same as that of the conventional air classifier shown in Fig. 1. The particles that have risen are transported to the classification blade 2
1 and 22, and are classified by receiving inertial force and centrifugal force, but the collision of particles with the classification blade at this time depends on the height of the classification blade and the circumferential speed of the classification blade, and both The larger both are, the higher the collision efficiency is.
In the present invention, the short classification blades 22 whose height decreases in the outer circumferential direction are installed between the conventionally formed long classification blades 21, so that the collision efficiency on the center side increases, and the collision efficiency on the center side increases. This counteracts the decrease in collision efficiency caused by a decrease in circumferential speed. Due to this effect, the collision efficiency is increased even in the vicinity of the classification blade attachment part, and the passage of coarse particles is reduced. Furthermore, the collision efficiency over the entire classification blade is made uniform, so that the inertial force of the particles is made uniform, and the separated particle size is brought to a constant value. Due to these effects, according to the present invention, it is possible to achieve the practical effects of reducing the straying of coarse powder into the fine powder side and improving the classification efficiency.

[Brief explanation of the drawing]

Figure 1 is a schematic longitudinal cross-sectional view of a conventional air classifier;
2 to 4 are schematic explanatory diagrams of one embodiment of the present invention, where FIG. 2 is a plan view and FIG. 3 is a
FIG. 4 is a sectional view taken along line A--B in FIG. 2. 21: Long classification blade, 22: Short classification blade whose height decreases toward the outside, 24: Dispersion plate, 2
5: Drive shaft.

Claims (1)

[Scope of utility model registration request] Long classification blades extending in the radial direction and short classification blades are attached alternately to the peripheral edge of the dispersion plate, and the short classification blades are formed so that their heights decrease toward the outside. An air classifier that is characterized by