JPH07155697A - Airflow classifier - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an air flow classifier capable of obtaining fine powder having a sharp particle size distribution. [Structure] As the guide plate 11, an outer peripheral end having an R as a counder block is provided, and a classifying plate 21 having a sharp outer peripheral end is provided below the guide plate. A cylindrical block 31 is detachably provided on the inner peripheral surface of the casing 51 to surround the R portion of the guide plate. The guide plate is detachably attached to the lower end portion of the rod-shaped support member 42 inserted into the exhaust pipe,
This support member can be raised and lowered from the outside. The R dimension of the guide plate is 25 to 35 mm. The classifying plate is composed of a main body 22 having a triangular pyramid shape, and a ring-shaped plate body 23 which is attachable to and detachable from the main body 22 and whose outer peripheral end has a sharp shape. The upper surface of the outer peripheral end of the plate 23 is an inclined surface (inclination angle is 5 ° or less) that descends from the inner peripheral portion of the plate to the outer peripheral portion, and the lower surface of the outer peripheral end of the plate is an upward inclined surface. The angle formed by these inclined surfaces is 40 to 60 °. The plate body has a thickness of 20 mm or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas stream classifier for accelerating the swirling speed of powder swirling in a classifying chamber to centrifuge the powder into fine powder and coarse powder.

[0002]

2. Description of the Related Art The classifier shown in FIG. 4 is known as the classifier. In this classifier, a guide plate 52 is provided at the connecting portion in a casing 51 formed by connecting an upper casing 51a and a lower casing 51b, and a classifying plate 53 is provided below the connecting plate, and the guide plate 52 and the classifying plate 53 are used. A classification chamber 54 is formed, and a large number of guide vanes 55 are provided on the entire circumference of the wall surface of the classification chamber 54 to form a secondary air supply member.
An exhaust pipe 56 is provided at the top of the upper casing 51a, a powder material supply pipe 57 is provided at the upper peripheral wall of the upper casing 51a, a fine powder discharge pipe 58 is provided at the center of the classification plate 53, and a coarse powder discharge pipe is provided at the lower end of the lower casing. 59 are connected to each other. In addition, 60 is a valve for adjusting the displacement, and 61 is the guide plate 5.
A column for supporting 2 and 62 are annular slits formed on the outer peripheral portion of the classifying plate 53.

In this classifier, the powder material is supplied from the supply pipe 57 into the upper casing 51a, and the secondary air is supplied from the guide vane 55 to the classifying chamber 54. As a result, the powder material swirls along the inner peripheral surface of the upper casing 51a, is separated from the air and flows into the classification chamber 54, is separated into fine powder and coarse powder by the secondary air, and the fine powder is discharged from the fine powder discharge pipe 58. The rough powder is discharged through the coarse powder discharge pipe 59.

In this type of classifier, the powder material is made to flow into the classifying chamber by the suction force of the high-pressure air supplied to the air injection nozzle, and the secondary air is connected to the upper part of the upper casing. There are known ones configured to supply from a secondary air supply pipe (Japanese Utility Model Publication No. 2-48076) and ones configured to adjust the height position of a classifying plate from the outside (Japanese Patent Application Laid-Open No. 3-174285). ing.

[0005]

However, in the conventional device shown in FIG. 4, the powder separated from the air by the swirling flow in the upper casing 51a is generated between the inner wall of the lower casing 51b and the outer peripheral end of the guide plate 52. The coarse powder and the fine powder are mixed in the gap, and after the mixed powder flows into the classification chamber 54, the classification plate 5 is subjected to the secondary air from the guide vanes 55.
When 3 is classified into coarse powder and fine powder, sufficient dispersion of the powder does not occur, so the classification accuracy deteriorates, and there is a problem that fine powder is mixed with coarse powder after classification and coarse powder is mixed with fine powder. It was

Further, when the powder material or the classification conditions are changed, the lower casing 51b, the guide plate 52, and the classification plate 53.
Although it is possible to improve the classification accuracy by adjusting the arrangement position of, the structure of the device has a limit.

Further, in the above conventional device, the guide plate 52
Since the support column 61, which is a supporting member for use in the lower casing 51b, is present in the lower casing 51b, the air in the upper and lower casings 51a and 51b is disturbed and the air flow swirl speed is reduced. Since the height position of 52 cannot be adjusted from the outside of the device, there is a problem that it is difficult to shorten the classification work.

The present invention has been made in view of the above points, and an object thereof is to provide an airflow classifier having excellent classification accuracy, which can obtain fine powder having a sharp particle size distribution.

[0009]

According to a first aspect of the present invention, there is provided an air flow classifier, which comprises a guide plate provided in a casing and a classifying plate provided below the guide plate to form a classifying chamber. The casing is provided with a secondary air supply member in which guide vanes are annularly arranged with a predetermined gap in the circumferential direction of the casing, and the secondary air flowing into the classification chamber through the secondary air supply member causes the inside of the classification chamber. In a method of accelerating the swirling speed of a swirling powder to centrifuge the powder into fine powder and coarse powder, the guide plate is provided with an R (R) that serves as a counder block at the outer peripheral end thereof. To do.

According to a second aspect of the present invention, there is provided the airflow type classifier according to the first aspect, wherein the outer peripheral end of the classifying plate has a sharp shape.

According to a third aspect of the present invention, there is provided the airflow classifier according to the second aspect, wherein the classifying plate is provided with a triangular pyramid-shaped main body, and is concentrically and detachably provided on the lower surface of the main body. And a ring-shaped member whose outer peripheral end is sharper than the outer diameter of the.

According to a fourth aspect of the present invention, there is provided an air flow type classifier according to the first aspect, in which a cylindrical block is detachably provided concentrically with the casing on the inner peripheral surface of the casing, and the block serves to guide the guide plate. It is characterized in that the R part is surrounded.

In the airflow classifier according to a fifth aspect, the guide plate according to the first aspect is inserted into an exhaust pipe provided in an upper casing without being supported by a column provided on an inner peripheral surface of the casing. It is characterized by being supported by a supporting member.

According to a sixth aspect of the present invention, there is provided the airflow classifier according to the fifth aspect, wherein the guide plate can be adjusted in a vertical position by an elevating operation of the supporting member.

According to a seventh aspect of the present invention, there is provided the airflow classifier according to the fifth or sixth aspect, wherein the guide plate is detachably attached to the support member.

[0016]

In the airflow classifier according to the first aspect of the present invention, the guide plate is provided with a radius R, which serves as a counder block, on the outer peripheral end of the guide plate so that the powder can be adjusted to have a particle size It can be sorted by size.

In the airflow classifier according to the second aspect of the present invention, the outer peripheral end of the classifying plate is formed into a sharp shape so that a stable airflow can be obtained in the classifying chamber which allows the powder to be screened by the Coanda effect. Can be formed.

In the airflow classifier according to the third aspect, the classifying plate having an appropriate edge shape according to the classification conditions can be obtained by replacing the ring-shaped member.

In the airflow classifier according to the fourth aspect, since the predetermined block is detachably provided, the radial positional relationship between the casing, the guide plate and the classifying plate can be made appropriate according to the classifying conditions. Can be set.

In the airflow classifier according to the fifth aspect, the guide plate is supported by the support member that is inserted through the exhaust pipe provided in the upper casing, so that the swirling airflow until the powder reaches the classification chamber. The decrease in speed is prevented, and the powder can be fed into the classification chamber while maintaining the speed.

In the airflow classifier according to the sixth aspect, the vertical position of the guide plate can be adjusted by lifting and lowering operations, so that the height of the classifying chamber can be made appropriate even during operation of the classifier. Since it can be adjusted, it is easy to set the optimum classification conditions.

In the airflow classifier according to claim 7, since the guide plate is detachably provided on the support member,
The guide plates can be replaced and the periodic cleaning work can be performed easily and quickly when the classification conditions are changed.

[0023]

The present invention will be described in more detail with reference to the embodiments shown in the drawings. Example 1 FIG. 1 is a longitudinal sectional view showing a main part of an airflow classifier, FIG. 2 is an enlarged view of a classifying plate in FIG. 1, and the same reference numerals as those in FIG. 4 denote the same or similar elements. There is.

In this airflow classifier, a guide plate 11 having an outer peripheral end portion with an R (R) as a counder block is provided in 51 (claim 1), and the outer peripheral end portion is formed into a sharp shape. The classified plate 21 is provided below the guide plate 11 (claim 2), and a cylindrical block 31 is detachably provided on the inner peripheral surface of the lower casing 51b. It is surrounded (Claim 4).

The preferred size of R of the guide plate 11 is 80 mm
Although it is a degree, since air swirls in the casing under normal classification conditions, it may be set to 25 to 35 mm.
The classifying plate 21 has a triangular pyramid-shaped main body 22 and a ring-shaped plate body 23 having an outer diameter larger than that of the main body 22 and a sharpened outer peripheral end portion on its lower surface, which is concentric with the main body 22 and is detachably attached. (Claim 3).

The upper surface of the outer peripheral end portion of the plate body 23 is formed as an inclined surface 23a having a downward slope from the inner peripheral portion of the plate body toward the outer peripheral portion, and the lower surface of the outer peripheral end portion is formed from the inner peripheral portion of the plate body. It is formed on the inclined surface 23b having an upward slope toward the outer peripheral portion. The inclination angle θ of the inclined surface 23a is preferably 5 ° or less. Further, the angle formed by the inclined surfaces 23a and 23b, that is, the edge angle α is 4
The range of 0 to 60 ° is preferable. Further, the thickness t of the plate body 23 is preferably 20 mm or more.

Since the optimum values of the inclination angle θ, the edge angle α and the thickness t differ depending on the kind of powder, the amount of powder supplied to the classifier and the classification point, it is important to confirm and set by experiments. is there. By replacing and installing the plate member 23 having the optimum shape and size for the classification conditions, it is possible to inexpensively configure a classifier capable of highly accurate classification.

Next, the operation of the classifier will be described. The powder raw material supplied together with air from the supply pipe 57 flows down along the inner peripheral surface of the upper casing 51a, passes through the guide plate 11, and is classified. Reach chamber 54. in this case,
The secondary air flowing from the guide vanes 55 and the exhaust air from the fine powder discharge pipe 58 and the coarse powder discharge pipe 59 cause the Coanda effect (Coanda e) around the R portion of the guide plate 11.
effect) occurs.

By the Coanda effect, the powder raw material is dispersed according to the size of the particle size, and the coarse powder l is converted into the lower casing 5.
It flows down in the 1b in a substantially vertical direction along the R portion, and is discharged from the coarse powder discharge pipe 59. The fine powder s flows in an arc shape along the R portion, turns around to the lower surface side of the guide plate 11, and is discharged from the fine powder discharge pipe 58 through the annular slit 62 provided in the classification chamber 54.

A part of the intermediate powder m (having a particle size larger than the classification point but smaller than the coarse powder 1) flows on the classification plate 21 together with the fine powder s, and the rest flows together with the coarse powder 1 on the classification plate 21. The intermediate powder m is pushed to the outer peripheral portion of the classification chamber 54 by the centrifugal force of the secondary air, and follows the locus similar to that of the coarse powder 1 from the annular slit 62.

In this case, since the classifying plate 21 is constructed by providing the plate body 23 having the sharp outer peripheral end concentrically with the main body 22, the powder dispersed by the Coanda effect of the R portion is the plate body 23. The edge portion of the outer peripheral end is accurately divided into coarse powder 1, medium powder m, and fine powder s. This is because turbulence of the air flow occurs at the outer peripheral end of the conventional classifying plate, whereas turbulence of the air flow is prevented by the edge of the plate body 23 in the classifying plate 21 of FIG. .

As described above, by providing the guide plate 11 with the R portion, the powder material is separated according to the particle size before flowing into the classification chamber 54, and the outer peripheral end of the classification plate 21 is sharply formed. As a result, turbulence of the air flow is prevented, so that the burden of air flow classification is reduced and the classification accuracy is significantly improved.

When carrying out classification using the Coanda effect, the classification point and classification accuracy are not limited to the shapes of the guide plate 11 and the classification plate 21 and the height of the classification chamber 54, but also to the gap between the lower casing 51b and the classification plate 21. It also largely depends on the width of the annular slit 62. These gaps and slit widths can be independently set to desired values, but since the lower casing 51b is provided, their positional relationships are fixed. Therefore, in the conventional classifier, the shape and size of the classification chamber can be arbitrarily set. Could not be set to.

On the other hand, in the classifier shown in FIG. 1, a cylindrical block 31 serving as a spacer is detachably provided on the entire circumference of the upper inner peripheral surface of the lower casing 51b so that a block having a shape and size preferable when changing the classification conditions. By replacing with 31 and setting the gap and slit width to appropriate values, it is possible to improve the classification accuracy.

When mounting the block 31, for example,
The outer peripheral portion is g8, and the inner peripheral surface of the lower casing 51b is G8.
Then, the height direction is fixed by sandwiching between the step portion 63 provided on the lower casing 51b and the flange 64 surface at the lower end portion of the upper casing 51a by fixing the circumferential direction by a gap fitting.

Example 2 This air flow type classifier has a guide plate 11 as shown in FIG.
The elbow portion 56a of the exhaust pipe 56 provided in the upper casing 51a instead of being supported by the lower casing 51b.
A bearing 41 is provided on the elbow portion 5 of the rod-shaped support member 42.
6a is inserted into the exhaust pipe 56, and the support member 42
Is supported by a bearing 41, a traverse mechanism 43 for raising and lowering the support member 42 is provided above the bearing 41, and a guide plate 11 is detachably attached to a lower end portion of the support member 41. The support member 42 and the guide plate 11 can be integrally moved up and down by rotating the handle 44 (claims 5, 6, 7).

In the conventional classifier shown in FIG. 4, the guide plate 52
When fixing with the support | pillar 61 attached to the lower casing 51b, the support | pillar 61 must be provided in 3-5 places,
For this reason, there has been a problem that the air flow is disturbed in the casing 51 and the air velocity is lowered.

On the other hand, in the classifier shown in FIG. 3, since the pillar 61 is removed, the air velocity is 3 to 4 compared with the conventional one.
Can be increased by%. In addition, the upper casing 51
The air velocity and direction in a are the same as before the support member 42 was provided, and the swirling flow of the powder is not adversely affected.

Further, in the conventional classifier shown in FIG. 4, when changing the height position of the classifying chamber 54, a flange type spacer (not shown) is attached to the guide vane 55, but the moving amount is finely adjusted. Since it is necessary to attach a large number of thin spacers to the
It was impossible to change the height.

On the other hand, in the classifier shown in FIG. 3, the height of the classifying chamber 54 can be easily and quickly increased or decreased by raising and lowering the guide plate 11 by operating the traverse mechanism 43 even when the classifier is in operation. It can be set to height. In addition, since the guide plate 11 is detachably attached to the support member 42, it is possible to efficiently replace the guide plate 11 and perform regular cleaning work in accordance with a change in the classification conditions. Since the bearing 41 is provided with a sealing function by packing, there is no leakage of powder or air to the outside of the traverse mechanism 43 or the classifier.

[0041]

As is apparent from the above description, in the classifier according to claim 1, the swirling flow is used to supply the powder material into the swirling flow, and the powder is generated in the relationship between the centrifugal force and the centripetal force of the air flow. In the airflow classifier that classifies the body to the set particle size, by adding R that becomes a counder block to the outer peripheral end of the guide plate,
Before the powder flows into the classification chamber, it can be sorted according to the size of the particle size, which reduces the entrainment of powder of different diameter in centrifugal airflow classification and enables high-precision classification.
There is an effect that a powder product having a sharp particle size distribution can be obtained. The classifier according to claim 2, wherein the swirling flow is used to supply the powder material into the swirling flow, and the powder is classified into a set particle size in accordance with the centrifugal force and the centripetal force of the air flow. By making the outer peripheral edge of the classifying plate sharp,
Since a stable airflow can be formed in the classification chamber that enables the powder to be screened by the Coanda effect, entrainment of different-diameter powder in centrifugal airflow type classification is reduced and high-precision classification is possible, resulting in a sharp A powder product with a particle size distribution can be obtained. In the classifier according to claim 3,
A powder material is supplied into the swirling flow by using a swirling flow, and in a gas stream classifier for classifying the powder to a set particle size by the relationship between the centrifugal force and the centripetal force of the air flow, a classifying plate is a triangular pyramid-shaped main body. , A ring-shaped member that is concentrically and removably provided on the lower surface of the main body and has an outer diameter larger than the outer diameter of the main body and a sharpened outer peripheral end portion, which is suitable for classification conditions. Since it can be a classifying plate with edge shape, entrainment of powder with different diameter in centrifugal airflow type classification is reduced and highly accurate classification is possible, and powder products with sharp particle size distribution can be obtained at low cost. To be The classifier according to claim 4, wherein a powder material is supplied into the swirl flow by using a swirl flow, and the powder is classified into a set particle size by the centrifugal force and centripetal force of the air flow. A cylindrical block is detachably provided on the inner peripheral surface of the casing, and the R portion of the guide plate is surrounded by the block, so that the radial positional relationship between the casing, the guide plate, and the classifying plate can be adjusted according to the classification conditions. Since it can be set to an appropriate value, entrainment of the different-diameter powder in the centrifugal airflow type classification is reduced, high-precision classification is possible, and a powder product having a sharp particle size distribution can be obtained. The classifier according to claim 5, wherein a powder material is supplied into the swirl flow by using a swirl flow, and the powder is classified into a set particle size according to a centrifugal force and a centripetal force of the air flow. The guide plate is supported by a support member that is inserted through the exhaust pipe provided in the upper casing without being supported by the lower casing, thereby preventing a decrease in the swirling air velocity until the powder reaches the classification chamber, Since the powder can be sent to the classifying chamber while maintaining its speed, the entrainment of different-diameter powder in centrifugal airflow type classification is reduced and high-precision classification is possible, and the powder product has a sharp particle size distribution. Can be obtained.
The classifier according to claim 6, wherein a powder material is supplied into the swirl flow by using a swirl flow, and the powder is classified into a set particle size by a relationship between centrifugal force and centripetal force of the air flow. By setting the guide plate so that the vertical position can be adjusted by raising and lowering the support member, the height of the classification chamber can be adjusted to an appropriate level even when the classifier is in operation, making it easy to set optimal classification conditions. As a result, entrainment of different-diameter powder in centrifugal airflow classification is reduced, high-precision classification is possible, and a powder product having a sharp particle size distribution can be obtained at low cost. Claim 7
In the classifier described in (1), a swirl flow is used to supply the powder material into the swirl flow, and the powder is classified into a set particle size according to the centrifugal force and centripetal force of the air flow. Since the support member is detachably attached to the support member, there is an effect that the guide plate can be replaced when the classification condition is changed, and regular cleaning work can be performed easily and quickly. As described above, the classifier of the present invention can be effectively applied to, for example, the production of dry toner, and can be widely used as a fine powder classifier.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a main part of an embodiment of the present invention.

FIG. 2 is an enlarged view of the classification plate of FIG.

FIG. 3 is a vertical cross-sectional view of another embodiment.

FIG. 4 is a vertical sectional view of a conventional example.

[Explanation of symbols]

 11, 52 Guide plate 21, 53 Classification plate 22 Main body 23 Plate body 23a, 23b Inclined surface 31 Block 41 Bearing 42 Support member 43 Traverse mechanism 44 Handle 51 Casing 51a Upper casing 51b Lower casing 54 Classification chamber 55 Guide vane 56 Exhaust pipe 56a Elbow part 57 Supply pipe 58 Fine powder discharge pipe 59 Coarse powder discharge pipe 60 Valve 61 Strut 62 Annular slit 63 Step part 64 Flange t Thickness α Edge angle θ Inclination angle

Claims (7)

[Claims] 1. A classification chamber is formed by a guide plate provided in the casing and a classification plate provided below the guide plate, and a large number of guide vanes are annularly arranged with a predetermined gap in the circumferential direction of the casing. A secondary air supply member is provided in the casing, and the secondary air flowing into the classifying chamber via the secondary air supply member accelerates the swirling speed of the powder swirling in the classifying chamber to turn the powder into fine powder. An airflow classifier characterized in that in the case of centrifugal separation with coarse powder, an R (R) that serves as a kounder block is attached to the outer peripheral end of the guide plate. 2. The airflow classifier according to claim 1, wherein an outer peripheral end of the classifying plate has a sharp shape. 3. The classifying plate is provided with a triangular pyramid-shaped main body, and is concentrically and detachably provided on the lower surface of the main body, and has an outer diameter larger than the outer diameter of the main body and a sharp outer peripheral end. 3. A ring-shaped member.
Airflow classifier described in. 4. A cylindrical block is removably provided on the inner peripheral surface of the casing and is concentric with the casing, and the R portion of the guide plate is surrounded by the block. Airflow classifier described. 5. The guide plate is supported by a support member, which is inserted into an exhaust pipe provided in an upper casing, without being supported by a support column provided on an inner peripheral surface of the casing. Airflow classifier described. 6. The airflow classifier according to claim 5, wherein the guide plate can be adjusted in vertical position by raising and lowering the support member. 7. The airflow classifier according to claim 5, wherein the guide plate is detachably provided on the support member.