JP2003080174A - Pneumatic classifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent wear of a shaft housing support component of a pneumatic classifier. SOLUTION: Wear of a stop bolt 10 of the pneumatic classifier is prevented by inserting a protective pipe 12 made of a ceramic into the outer peripheral of the stop bolt 10 as a support component to support the shaft housing 4 which is inserted from the outside of an exhaust pipe 1a in the upper part of a casing 1 of the pneumatic classifier and stores a rotation shaft 3 of a classification vane 2 so as not to allow powder in a high speed which passes through the classification vane 2 to directly collide against the stop bolt 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow classifier for classifying powder according to its size.

[0002]

2. Description of the Related Art An air-flow classifier for classifying powder according to its size is, for example, an embodiment of the present invention shown in FIG.
As shown in FIG. 3, a type in which a rotating shaft 3 having a classification blade 2 attached at its tip is housed and arranged in a cylindrical shaft housing 4 is often used in a casing 1 to which powder is supplied.

In this airflow type classifier, the powder supplied from the lower side of the casing 1 is the exhaust pipe 1 above the casing 1.
Among powders that are rotated by the classifying blade 2 while being sucked together with air by the air exhauster (not shown) connected to a and rising,
Coarse powder on which a large centrifugal force acts is ejected from the classification blade 2 to the outer peripheral side and falls inside the casing 1, and only fine powder having a small centrifugal force passes through the classification blade 2 and is discharged from the exhaust pipe 1a. There is.

[0004]

In the airflow classifier of the type described above, a shaft housing for accommodating the rotating shaft is usually provided so as to protrude from the inner wall of the casing in order to smoothly rotate the rotating shaft to which the classifying blade is attached. It is supported by the supporting member. However, this support member is rapidly worn because the powder that has passed through the classification blade and is sent to the discharge end at high speed collides with it. If the operation is continued in the state where the wear of the support member is large, the shaft housing cannot be sufficiently supported, the rotating shaft cannot rotate smoothly, and the classifier may be damaged. For this reason, the support member must be replaced frequently, which increases the running cost of the classifier.

Such wear of the support member can be suppressed to some extent by performing hardfacing welding on the surface of the support member or attaching a wear resistant member such as a ceramic piece to the surface. The effect is small when the hardness of the powder is high, and there is a risk of peeling due to collision of the powder when sticking a ceramic piece or the like. It is also conceivable that the support member itself is made of a wear-resistant material such as ceramics to make it less likely to wear, but this is not preferable as a support member because it increases the manufacturing cost and lowers the strength.

Therefore, an object of the present invention is to effectively prevent wear of a shaft housing supporting member of an airflow classifier.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a rotating shaft having a classification blade attached to its tip is housed in a cylindrical shaft housing in a casing to which powder is supplied. In the airflow classifier in which the shaft housing is supported by a supporting member protruding from the inner wall of the casing, the supporting member is covered with a protective tube.

That is, by covering the support member of the shaft housing with the protective tube, the high-speed powder passing through the classifying blades is prevented from directly colliding with the support member, and the wear of the support member is prevented.

By making the direction of the protection tube covering the support member changeable in the axial direction or the circumferential direction of the support member, the wear is likely to progress in a small wear area in accordance with the wear state of the protection tube. By changing the direction of the protection tube so that it is arranged at the position, the replacement cycle of the protection tube can be extended and the cost for replacement can be suppressed.

By dividing the protective tube in the axial direction or in the circumferential direction and making it possible to replace each of the divided parts, it is possible to replace only a portion having a large amount of wear, thereby suppressing the replacement cost of the protective tube. You can

The protective tube is divided into equal size in the axial direction or the circumferential direction, and the divided parts can be exchanged with each other, so that the large wear portion and the small wear portion are exchanged with each other. The replacement cost can be further reduced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows an embodiment of an airflow classifier provided on the upper part of the casing of the crusher.
As described above, in this airflow classifier, the rotary shaft 3 having the classifying blade 2 attached to the tip thereof is housed in the cylindrical shaft housing 4 and vertically arranged in the casing 1 having a large opening downward. It is a thing.

A chute 5 is provided on a side portion of the casing 1 for feeding a raw material toward a pulverizer (not shown) disposed below the classifier, and an opening edge portion at a lower end of the casing 1 is It is connected to the opening edge at the upper end of the casing 6 that covers the periphery of the crusher. Further, an exhaust pipe 1a is provided on the upper part of the casing 1 and is connected to an exhaust fan (not shown), and a shaft housing 4 accommodating a rotating shaft 3 is arranged in the exhaust pipe 1a.

The rotary shaft 3 is connected at its base end to a drive unit 7 arranged above the casing 1, and is rotatably supported by bearings 8 provided at the upper and lower ends of the shaft housing 4. . A blade attachment member 9 having two disc portions 9a connected to each other is fitted at the tip of the rotary shaft 3, and a large number of classification vanes 2 radially extend to the peripheral edge of each disc portion 9a. Is installed as.

As shown in FIG. 2, the shaft housing 4 serves as a support member inserted from the outside of the exhaust pipe 1a above the casing 1 at six locations in the vicinity of the lower end thereof along the circumferential direction. It is supported by stop bolts 10.

Each of the fixing bolts 10 is made of structural steel, and as shown in FIG. 3, an end bolt 11 in which a threaded portion 10a for forming the tip portion is fitted in a concave portion on the outer circumference of the shaft housing 4. Exhaust stack 1a
The shaft housing 4 is supported by tightening a nut from the outside. And FIG.
As also shown in FIG. 2, a protective tube 12 is fitted on the outer periphery of the portion of each stop bolt 10 projecting from the inner wall of the exhaust pipe 1a. Each of these protective tubes 12 is made of ceramics and is divided into four equal-sized ring members 12a.

Next, the flow of powder in this air flow type classifier will be described. In this embodiment, first, the raw material charged from the chute 5 on the side of the casing 1 is pulverized by the pulverizer below the classifier, and the pulverized powder is pulverized together with air by the air exhauster connected to the exhaust pipe 1a. It is sucked up from the casing 6 of the machine into the casing 1 of the classifier. As described above, the powder that rises in the casing 1 is given a rotary motion around the rotary shaft 3 by the classifying blade 2 on the way, and among the powder that rotates, a coarse centrifugal force acts on the powder. The powder jumps from the classification blade 2 to the outer peripheral side and falls inside the casing 1, and only fine powder having a small centrifugal force passes through the classification blade 2 and is discharged from the exhaust tube 1a.

The fine powder that has passed through the classifying blade 2 is exhausted from the exhaust stack 1a.
It is sent at a high speed of about 20 m / sec. At this time, part of the fine powder collides with the protective tube 12 covering the stop bolt 10, so that the protective tube 12 gradually wears. The manner of progress of wear of the protective tube 12 varies depending on the site, and the lower half near the inner wall of the exhaust pipe 1a where the flow velocity of the impinging fine particles is high is most likely to wear. On the other hand, set bolt 10 that does not directly collide with fine powder
Does not wear at all.

Therefore, in this air flow classifier, it is possible to eliminate the replacement of the set bolt 10 due to wear while ensuring the strength of the set bolt 10 as a support member. On the other hand, although it is necessary to replace the protective tube 12 due to wear, the protective tube 12 is made of ceramics having high wear resistance, so the frequency of replacement work is considerably less than in the conventional case. Further, since the protection tube 12 is divided into ring members 12a having the same size, depending on the wear condition of each ring member 12a, only the one with large wear may be replaced, or the one with large wear may be replaced with the one with large wear. By replacing it,
The cost for replacing the protection tube 12 can be suppressed. Further, 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 shortened.

The material of the protective tube 12 is not limited to ceramics, but may be a sintered metal containing tungsten carbide or the like.
It is also possible to use a material having more excellent wear resistance. Even if such a material that is difficult to mold is used, the protective tube 1
Since 2 is divided into small and simple ring members 12a, it can be manufactured relatively inexpensively.

Further, in this embodiment, the protective tube is divided into equal size in the axial direction, but it may be divided in the circumferential direction, for example, by dividing into two vertically. Also in this case, the replacement cost can be suppressed by partially replacing or replacing each of the divided parts according to the difference in the progress of wear in the circumferential direction. Further, in the case of only partially exchanging each part divided in the axial direction or the circumferential direction, each part does not necessarily have to have the same size.

FIG. 4 shows a modification of the protection tube. In this modification, three key grooves 13a are provided on the inner circumference of the integrally formed protective tube 13 at equal intervals in the circumferential direction, and any one of these key grooves 13a is not shown in the drawing. 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 into the key of the stop bolt, the protection tube 1
The direction of 3 can be changed to the circumferential direction of the stop bolt. Therefore, by changing the direction of the protection tube 13 so that the portion with less wear is located at a position where it is more easily worn, the replacement cycle of the protection tube 13 can be extended and the replacement cost can be suppressed.

In the modification described above, the direction of the protective tube can be changed in the circumferential direction of the stop bolt, but the direction of the protective tube can be changed in the axial direction of the stop bolt. That is, by changing the positions of both ends of the protection tube according to the difference in the axial wear state of the protection tube,
The replacement cycle can be extended.

[0024]

As described above, in the airflow classifier of the present invention, by covering the support member of the shaft housing with the protective tube, high speed powder is prevented from directly colliding with the support member, and the support member of the support member is prevented. Since the wear is prevented, it is not necessary to replace the support member. Therefore, by using a material having high wear resistance for the protective tube, it is possible to significantly reduce the frequency of replacement work and suppress the running cost.

[Brief description of 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 of FIG.

FIG. 3 is an enlarged vertical sectional view taken along line BB of FIG.

FIG. 4 is an external perspective view of one end of a modified example of the protective tube used in the airflow classifier of FIG.

[Explanation of symbols]

1 casing 1a Exhaust stack 2 classification blades 3 rotation axes 4 shaft housing 5 shoots 6 casing 7 Drive 8 bearings 9 Mounting member 9a Disc part 10 stop bolt 10a Female thread 11 End bolt 12 Protection tube 12a ring member 13 Protection tube 13a keyway

Claims (4)

[Claims] 1. A support in which a rotary shaft having a classification blade attached to its tip is housed and arranged in a cylindrical shaft housing in a casing to which powder is supplied, and the shaft housing is projected from an inner wall of the casing. An airflow classifier supported by a member, wherein the supporting member is covered with a protective tube. 2. The airflow classifier according to claim 1, wherein the direction of the protective tube covering the support member can be changed in the axial direction or the circumferential direction of the support member. 3. The airflow classifier according to claim 1, wherein the protection tube is divided in the axial direction or the circumferential direction, and each divided portion can be replaced. 4. The airflow classifier according to claim 3, wherein the protective tube is divided into equal sizes in the axial direction or the circumferential direction, and the divided parts can be replaced with each other.