JP4643078B2 - Airflow classifier - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an airflow classifier that classifies powder according to its size.
[0002]
[Prior art]
As an airflow classifier that classifies powder according to its size, for example, as shown in FIG. 1 which is an embodiment of the present invention, a classification blade 2 is provided at the tip in a casing 1 to which powder is supplied. A type in which the attached rotating shaft 3 is housed in a cylindrical shaft housing 4 and arranged is often used.
[0003]
In this airflow classifier, the powder supplied from the lower side of the casing 1 is sucked together with the air to the exhaust fan (not shown) connected to the exhaust pipe 1a at the upper part of the casing 1 and rises. Rotation around the rotary shaft 3 is given by the rotary powder, and the coarse powder on which the large centrifugal force acts out of the rotating powder jumps out from the classification blade 2 to the outer peripheral side and falls in the casing 1, and the centrifugal force is small. Only the fine powder passes through the classification blade 2 and is discharged from the exhaust cylinder 1a.
[0004]
[Problems to be solved by the invention]
In the airflow classifier of the type described above, the shaft housing that houses the rotating shaft is usually supported by a support member that protrudes from the inner wall of the casing in order to smoothly rotate the rotating shaft to which the classifying blades are attached. However, since this support member collides with the powder that passes through the classification blade and is fed to the discharge end at a high speed, the wear progresses quickly. If the operation is continued in a state where the wear of the support member is increased, the shaft housing cannot be sufficiently supported, the rotating shaft cannot be smoothly rotated, and the classifier may be damaged. For this reason, it is necessary to replace the support member frequently, which raises the running cost of the classifier.
[0005]
Such wear of the support member can be suppressed to some extent by performing hard build-up welding on the surface of the support member or attaching a wear-resistant member such as a ceramic piece. The effect is small when the hardness is high, and there is a risk of peeling due to powder collision when sticking a ceramic piece or the like. Although it is conceivable that the support member itself is made of a wear-resistant material such as ceramics to make it difficult to wear, it is not preferable as a support member because the manufacturing cost increases and the strength decreases.
[0006]
Then, the subject of this invention is preventing the abrasion of the shaft housing support member of an airflow classifier effectively.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is arranged in such a manner that a rotating shaft having a classification blade attached to the tip is accommodated in a cylindrical shaft housing in a casing to which powder is supplied, and the shaft housing is disposed in the casing. In the airflow classifier supported by a support member projecting from the inner wall of the above, a configuration in which the support member is covered with a protective tube is adopted.
[0008]
That is, by covering the support member of the shaft housing with the protective tube, the high-speed powder that has passed through the classification blade is prevented from directly colliding with the support member, thereby preventing the support member from being worn.
[0009]
By enabling the orientation of the protective tube covering the support member to be changed in the axial direction or circumferential direction of the support member, a portion with low wear is arranged at a position where wear tends to progress depending on the wear state of the protective tube. Thus, the direction of the protective tube can be changed to extend the replacement period of the protective tube, and the cost for replacement can be suppressed.
[0010]
By dividing the protective tube in the axial direction or the circumferential direction and making it possible to replace each of the divided parts, it is possible to suppress the replacement cost of the protective tube by exchanging only the portion with large wear.
[0011]
The protective tube is divided into equal dimensions in the axial direction or the circumferential direction, and the divided parts can be replaced with each other, so that the parts with large wear and the small parts are replaced, and the replacement cost of the protective pipe is reduced. It can be further reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an embodiment of an airflow classifier provided on an upper part of a casing of a pulverizer. In this airflow classifier, as described above, a rotating shaft 3 having a classification blade 2 attached to the tip is accommodated in a cylindrical shaft housing 4 and arranged vertically in a casing 1 that is greatly opened downward. Is.
[0013]
The side of the casing 1 is provided with a chute 5 for charging the raw material toward a pulverizer (not shown) disposed below the classifier, and an opening edge at the lower end of the casing 1 is formed on the side of the pulverizer. It connects to the opening edge part of the upper end of the casing 6 which covers the circumference | surroundings. An exhaust cylinder 1a is provided at the upper part of the casing 1 and connected to an exhaust fan (not shown). A shaft housing 4 in which the rotary shaft 3 is housed is disposed in the exhaust cylinder 1a.
[0014]
The rotating shaft 3 is connected to a driving device 7 having a base end portion disposed above the casing 1 and is rotatably supported by bearings 8 provided at the upper end portion and the lower end portion of the shaft housing 4. A blade mounting member 9 having two disk portions 9a connected to each other is fitted at the tip of the rotating shaft 3, and a large number of classification blades 2 project radially from the peripheral edge of each disk portion 9a. It is attached as follows.
[0015]
As shown in FIG. 2, the shaft housing 4 is a set bolt 10 as a support member inserted from the outside of the exhaust pipe 1 a at the upper part of the casing 1 at six locations along the circumferential direction in the vicinity of the lower end portion thereof. It is supported by.
[0016]
Each of the set bolts 10 is made of structural steel. As shown in FIG. 3, the threaded portion 10 a is screwed to the end bolt 11 fitted in the recess on the outer periphery of the shaft housing 4. The shaft housing 4 is supported by tightening with a nut from the outside of the exhaust tube 1a. As shown in FIGS. 1 and 2, the protective tube 12 is fitted on the outer periphery of the portion of each set bolt 10 protruding from the inner wall of the exhaust tube 1 a. Each of these protective tubes 12 is made of ceramics and is divided into four equal-sized ring members 12a.
[0017]
Next, the flow of powder in this airflow classifier will be described. In this embodiment, first, the raw material introduced from the chute 5 on the side of the casing 1 is pulverized by a pulverizer below the classifier, and the pulverized powder is pulverized together with air by an exhaust fan connected to the exhaust tube 1a. Suction from the machine casing 6 to the classifier casing 1. As described above, the powder rising in the casing 1 is given a rotational movement around the rotation shaft 3 by the classifying blade 2 in the middle, and the coarse powder to which a large centrifugal force acts on the rotationally moving powder. The powder jumps out from the classification blade 2 to the outer peripheral side and falls in the casing 1, and only the fine powder having a small centrifugal force passes through the classification blade 2 and is discharged from the exhaust pipe 1 a.
[0018]
The fine powder that has passed through the classification blade 2 is sent through the exhaust pipe 1a at a high speed of about 20 m / second. At this time, since a part of the fine powder collides with the protective tube 12 covering the set bolt 10, the protective tube 12 is gradually worn. The progress of wear of the protective tube 12 differs depending on the part, and the lower half near the inner wall of the exhaust pipe 1a where the flow velocity of the colliding fine powder is fast is most likely to be worn. On the other hand, the set bolt 10 on which the fine powder does not directly collide is not worn at all.
[0019]
Therefore, in this airflow classifier, replacement due to wear of the set bolt 10 can be eliminated while securing the strength of the set bolt 10 as a support member. On the other hand, replacement due to wear of the protective tube 12 is necessary, but since the protective tube 12 is formed of ceramics having high wear resistance, the frequency of replacement work can be considerably reduced as compared with the conventional case. Moreover, since the protective tube 12 is divided | segmented into the equal-sized ring member 12a, according to the wear condition of each ring member 12a, only the thing with large wear is replaced | exchanged, and the thing with big wear is small. By replacing it, the cost for replacement of the protective tube 12 can be suppressed. Furthermore, since a large number of ring members 12a having the same shape are manufactured as replacement equipment, the manufacturing cost is reduced and the delivery time is also shortened.
[0020]
In addition, the material of the protective tube 12 is not limited to ceramics, and a material having higher wear resistance such as a sintered metal containing tungsten carbide can also be used. Even when such a difficult-to-mold material is used, since the protective tube 12 is divided into small and simple ring members 12a, it can be manufactured relatively inexpensively.
[0021]
Moreover, in this embodiment, although the protective tube was divided | segmented into the same dimension in the axial direction, you may divide | segment into the circumferential direction, for example, dividing into 2 parts up and down. Also in this case, the replacement cost can be suppressed by performing partial replacement or replacement of each divided part according to the difference in the progress of wear in the circumferential direction. Furthermore, when only partial replacement of each part divided in the axial direction or the circumferential direction is performed, the parts do not necessarily have to be the same size.
[0022]
FIG. 4 shows a modification of the protective tube. In this modification, three key grooves 13a are provided at equal intervals in the circumferential direction on the inner periphery of the integrally formed protective tube 13, and any one of these key grooves 13a is not shown in the figure. The protective tube 13 is fixed by being fitted into a key provided on the outer periphery of the protective tube 13. That is, by changing the key groove 13a fitted in the key of the set bolt, the direction of the protective tube 13 can be changed in the circumferential direction of the set bolt. Therefore, by changing the direction of the protective tube 13 so as to place the portion with low wear at a position where it is easy to wear, the replacement cycle of the protective tube 13 can be extended and the replacement cost can be suppressed.
[0023]
In the modification described above, the direction of the protective tube can be changed in the circumferential direction of the stop bolt. However, the direction of the protective tube may be changed in the axial direction of the stop bolt. That is, the replacement cycle can be extended by replacing the positions of both ends of the protective tube according to the difference in the wear state in the axial direction of the protective tube.
[0024]
【The invention's effect】
As described above, the airflow classifier of the present invention prevents wear of the support member by covering the support member of the shaft housing with a protective tube so that high-speed powder does not directly collide with the support member. Therefore, it is not necessary to replace the support member.
Therefore, using a highly wear-resistant material for the protective tube, the frequency of replacement work can be greatly reduced, and running costs can be reduced.
[Brief description of the drawings]
FIG. 1 is a front sectional view of an airflow classifier according to an embodiment. FIG. 2 is a plan sectional view taken along line AA in FIG. 1. FIG. 3 is an enlarged longitudinal sectional view taken along line BB in FIG. 4 is an external perspective view of one end of a modified example of a protective tube used in the airflow classifier of FIG.
DESCRIPTION OF SYMBOLS 1 Casing 1a Exhaust cylinder 2 Classifying blade 3 Rotating shaft 4 Shaft housing 5 Chute 6 Casing 7 Driving device 8 Bearing 9 Mounting member 9a Disk part 10 Set bolt 10a Female thread part 11 End bolt 12 Protection pipe 12a Ring member 13 Protection pipe 13a Keyway

Claims (4)

An airflow in which a rotating shaft with a classification blade attached to the tip is housed and disposed in a cylindrical shaft housing in a casing to which powder is supplied, and the shaft housing is supported by a support member protruding from the inner wall of the casing In the air classifier, the support member is covered with a protective tube. The airflow classifier according to claim 1, wherein a direction of a protective tube covering the support member can be changed in an axial direction or a circumferential direction of the support member. The airflow classifier according to claim 1, wherein the protective tube is divided in an axial direction or a circumferential direction, and can be exchanged for each divided part. The airflow classifier according to claim 3, wherein the protective tube is divided into equal dimensions in the axial direction or the circumferential direction, and the divided parts can be replaced with each other.

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