JPH0938580A - Classifying machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a classifier of a simple structure which attains increase in production and in a yield, especially the yield of a small-sized powder. SOLUTION: In a classifier which is composed of a raw material supply passage, a primary exhaust gas passage, a dispersion chamber, a classification chamber, an upper classification board, a lower classification board, a ring- shaped slit formed in the side wall of the classification chamber, a fine powder removing passage, and a coarse powder removing part and separates a fine powder of a specified size and a coarse powder of a size larger than a specified size, the inside diameter of the ring-shaped slit 42 is inclined to expand gradually downward, and the inclination angle θ is 6-12 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a classifier used in the manufacturing process of dry powder such as toner (powder used in electrophotographic developing systems such as copying machines, fax machines and laser printers). More specifically, the present invention relates to an improvement of the classifier which improves productivity (production amount and yield), and particularly improves productivity of powder having a small particle size.

[0002]

2. Description of the Related Art Toners used in electrophotographic development systems, some powdery chemicals, powdered chemicals, powdered foods, etc. are dried in a relatively large lump of raw material. In this state, it is crushed by a crusher to obtain a product powder having a predetermined diameter.

The dry pulverization process of powder will be described with reference to a toner used in an electrophotographic developing system as an example.
As shown in FIG. Referring to FIG. 2, a raw material 1 of the toner in a relatively large lump is supplied to a hopper 2, and the hopper 2 supplies the raw material 1 to a coarse powder cutting classifier 4. The coarse powder cutting classifier 4 is a cyclone type classifier, which feeds toner powder particles having a predetermined diameter or smaller to the classifier 5 and jets toner powder particles having a predetermined diameter or larger to the lower jet pulverizer 6
Send to The jet pulverizer 6 further pulverizes the toner powder particles having a predetermined diameter or more, and returns the toner powder particles to the coarse powder cut classifier 4 again via the circulation path 7. The fine toner powder generated in the pulverizing and classifying process is introduced into the bag filter 9 through the path 8 and collected.

The classifier 5 cuts the fine powder remaining on the toner powder particles classified by the coarse powder cut classifier 4, and the fine powder cut by the classifier 5 is the same as above. It is introduced into the bag filter 9 via the path 8.
The toner powder particles from which the fine powder has been removed are sent to a fine powder cut classifier 11 by an air-type feeder 10, and product powder particles having a diameter within a predetermined range are collected in a recovery tank 12 to collect powder particles having a diameter smaller than a predetermined diameter. It is sent to the collection cyclone 13. The fine powder generated in this step is also introduced into the bag filter 9 via the path 8.

The collecting cyclone 13 collects toner powder particles having a diameter smaller than a predetermined value which cannot be used as toner in a collecting tank 14,
This is either discarded or reused. The fine powder generated in the collection cyclone 13 is also introduced into the bag filter 9 via the path 8.

The structures of the coarse-powder cutting classifier 4 and the fine-powder cutting classifier 11 used in the dry crushing device are as shown in FIG. That is, the classifier 21 represented by the coarse powder cutting classifier 4 and the fine powder cutting classifier 11 and the like.
Is composed of a raw material supply passage 22, a primary exhaust passage 23, a dispersion chamber 24, a classification chamber 25, a fine particle extracting passage 26, and a coarse particle extracting portion 27.

The supply passage 22 is for supplying the primary air and the raw material, and is attached to the side surface of the dispersion chamber 24. The primary exhaust passage 23 is for feeding the fine powder in the dispersion chamber 24 to the bag filter (see FIG. 2), and is provided at the center of the upper portion of the dispersion chamber 24. The dispersion chamber 24 is a chamber in which the primary air and the raw material supplied from the supply passage 22 swirl and flow in a cyclone shape.

The classifying chamber 25 is provided below the dispersion chamber 22 and is partitioned by an upper partial classifying plate 28 and a lower partial classifying plate 29. A secondary air supply passage 31 is provided in the side wall 30 of the classification chamber 25, and the secondary air is supplied from the secondary air supply passage 31 into the classification chamber 25. The upper part grade plate 28 has a conical shape that is convex toward the upper side, and a gap H1 is provided between the upper part grade plate 28 and the ring-shaped slit 30A provided on the side wall 30. Also,
The lower part grade plate 29 also has a conical shape that is convex toward the upper side, and a gap H2 is provided between it and the side wall 30.
The fine particle take-out passage 26 is opened near the center of the lower part grader 29 and takes out fine particles together with air. The coarse particle takeout unit 27 is provided below the classification chamber 25, and collects and discharges the coarse particles that have fallen from the gap H2 around the lower partial classifying plate 29.

The operation of the classifier 21 configured as described above will be described below. The primary air and the raw material supplied from the supply passage 22 swirl and flow like a cyclone inside the dispersion chamber 24, and the fine powder is sent to the bag filter (see FIG. 2) together with the air through the primary exhaust passage 23.

Fine particles and coarse particles in the dispersion chamber 24 are the upper part grader 2
It falls from the gap H1 around 9 into the classification chamber 25. The air supplied from the secondary air supply passage 31 swirls in a cyclone shape in the classifying chamber 25, and the fine particles and coarse particles that have fallen swirl together with the air. Then, the heavy coarse particles fall from the gap H2 around the lower part grader 29 and are taken out from the coarse particle take-out portion 27, and the fine particles are taken out from the fine particle take-out passage 26.
Taken out with air.

In the conventional classifier, as shown in FIG. 4, a ring-shaped slit 30A provided around the upper partial classifying plate 28 is provided vertically (inclination angle is 0 °).

[0012]

In the powder crushing and manufacturing apparatus, if the amount of raw material supplied to the classifier is increased to increase the production amount, the yield of the product powder decreases. There is a characteristic that. On the other hand, in the above-mentioned conventionally known classifier, the range of the particle diameter is small, for example, in the case of toner,
The yield was not so good with a powder pair having an average particle size of 15 μm or less, particularly 12 μm or less. Therefore, an object of the present invention is to improve a part of the structure of the conventionally known classifier, increase the production amount with a simple structure, and increase the yield, especially a classifier that achieves an increase in the yield of powder having a small diameter. To provide.

[0013]

A feature of the present invention is that a raw material supply passage, a primary exhaust passage, a dispersion chamber,
A classifying chamber, an upper part classifying plate, a lower part classifying plate, a ring-shaped slit provided on the side wall of the classifying chamber, a fine particle extracting passage, and a coarse particle extracting part, and fine particles having a predetermined diameter and a predetermined size. In a classifier configured to separate coarse particles having a diameter equal to or larger than the diameter, the inner diameter of the ring-shaped slit is inclined so as to gradually expand downward.

Another feature of the present invention is that the inclination angle of the ring-shaped slit is 6 ° to 12 °.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an upper partial grader and a ring-shaped slit of a classifier according to an embodiment of the present invention.

Referring to FIG. 1, in the present invention, a ring-shaped slit 42 arranged around the upper part grade plate 41 is formed such that the diameter D is enlarged downward. The length of the ring-shaped slit 42 is L. It was also found that when the expansion of the diameter D is represented by an inclination angle θ with respect to the vertical direction, a range of 6 ° to 12 ° is desirable.

Next, with respect to the inclined ring-shaped slit 42 of the present invention and the conventional non-tilted ring-shaped slit, Table 1 and Table 2 are used to compare the yields during use.

[0018]

[Table 1] (Note) Length of ring-shaped slit L: 124 mm N36 is the conventional tilt angle θ: 0 °, D: φ20
6 TP24 is the tilt angle θ of the present invention: 6 °, D: φ23
0 TP8 is the inclination angle of the present invention θ: 12 °, D: φ26
Two

[0019]

[Table 2] (Note) Length of ring-shaped slit L: 224 mm N36 is the conventional inclination angle θ: 0 °, D: φ390 TP24 is the inclination angle θ: 6 °, D: φ438 of the present invention. Same as Table 1

Tables 1 and 2 show the yields when the inclination angle θ is 0 ° (conventional type), 6 °, and 12 °, and the raw material powder is finely cut to obtain powders having an average particle diameter of 7μ, 9μ, and 11μ. It is measured in the case of classification into. As can be seen from Table 1 and Table 2, when the ring-shaped slit having the inclination angle of the present invention is used, there is no conventional inclination angle in the range of powder having a relatively small particle diameter (particle diameter 7 μ, 9 μ, 11 μ). An increase in yield is achieved in comparison with that of products.

Next, referring to Table 3, the increase in the production amount according to the present invention will be described. Generally, the yield decreases as the amount of raw material supplied increases. However, according to the structure of the present invention, the yield is not decreased even if the supply amount of the raw material is increased, so that the production amount can be increased accordingly.

[0022]

[Table 3] (Note) The yield is 10 when the feed rate is 3 kg / H.
The value N0 at 0% is the conventional inclination angle θ: 0 °, D: φ20.
6 TP24 is the tilt angle θ of the present invention: 6 °, D: φ23
0 TP14 is the inclination angle θ of the present invention: 10 °, D: φ25
0 TP8 is the inclination angle of the present invention θ: 12 °, D: φ26
Two

Table 3 shows the results of examining the relationship between the feed amount and the yield using the same classifier as in Table 1. According to the conventional structure, as the ring-shaped slit is seen in N36, the yield is significantly decreased when the supply amount of the raw material is increased. However, in the slit provided with the inclined structure of the present invention, the yield does not decrease so much even if the supply amount of the raw material is increased.

The structure described above is one embodiment of the present invention, and the present invention is not limited to the above embodiments. For example, as shown in FIG. 1, various numerical values are adopted for the specifications (D, L, H1, α) of the upper part classifying plate 41 and the ring-shaped slit 42, and the size of the classifier, etc. The effect of the present invention occurs regardless of the above.

[0025]

The effects of the present invention having the above-described structure are as follows. According to the invention,
The yield is increased and productivity is improved in the range where the diameter of the particles is small. Further, even if the production amount is increased by increasing the supply amount of the raw material to the classifier, the yield of the product powder does not decrease.

[Brief description of drawings]

FIG. 1 is a sectional view showing an inclined ring-shaped slit showing an embodiment of the present invention.

FIG. 2 is a system diagram showing a conventionally known toner pulverizing process.

FIG. 3 is a cross-sectional view showing a conventionally known classifier.

FIG. 4 is a cross-sectional view showing a conventionally known ring slit without inclination.

[Explanation of symbols]

 41 Upper part grade plate 42 Ring slit 42 θ Inclination angle H1 Gap D Inner diameter

Front page continuation (72) Masahito Nakajima, 3-1, Soba-cho, Shizuoka-shi, Shizuoka-shi, Tomoegawa Paper Mill Co., Ltd. (72) Takashi Koizumi, 3-1, Soba-machi, Shizuoka-shi, Shizuoka Inside the paper mill

Claims (2)

[Claims] 1. A raw material supply passage, a primary exhaust passage, a dispersion chamber, a classifying chamber, an upper partial classifying plate, a lower partial classifying plate, a ring-shaped slit provided on the side wall of the classifying chamber, and fine particles. In a classifier consisting of a take-out passage and a coarse-grain take-out section, which separates fine particles having a predetermined diameter and coarse particles having a diameter not less than a predetermined diameter, the inner diameter of the ring-shaped slit is gradually downward. A classifier characterized by being inclined so as to expand to. 2. The classifier according to claim 1, wherein the angle of inclination of the ring-shaped slit is 6 ° to 12 °.