JP2000140675A - Pulverizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulverizer by which material to be pulverized is effectively ground. SOLUTION: Compressed air fed to an inlet 13 of an accelerating nozzle 12 is throttled at a throat part 14 and is expanded at a diffuser part 15 installed on the downstream side of the throat part 14 to form a jet air current. Material to be pulverized is fed into the jet flow current from a feeding port 17 formed in the peripheral wall of the diffuser part 15 to hit the material to be pulverized against an impingement plate 4 to pulverize it. In the throat part 14, a circular- arcuate inner surface 14a smoothly connecting with the inner surface of the inlet 13, and the tapered inner surface of the diffuser part 15 is formed to prevent turbulence from being generated in the compressed gas flowing from the inlet 13 to the throat part 14, and by formation of the fast jet air current, pulverizing efficiency of the material to be pulverized is increased and also fine grinding is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collision type pulverizer using a compressed gas.

[0002]

2. Description of the Related Art A collision type pulverizing apparatus forms a jet jet by a compressed gas, supplies an object to be pulverized such as toner into the jet jet, and makes the object to collide with a collision member. The object to be crushed is crushed by the impact.

[0003] As the above-mentioned pulverizing apparatus, the one shown in FIG. 5 has been conventionally known. In this pulverizing apparatus, an acceleration nozzle 2 is connected to the tip of a compressed gas supply nozzle 1, and a collision member 4 is provided in a pulverization chamber 3 provided in front of the acceleration nozzle 2.

The accelerating nozzle 2 forms a throat 6 downstream of the inlet 5 communicating with the supply nozzle 1. The throat 6 narrows down the compressed gas supplied to the inlet 5 to increase the pressure, thereby increasing the pressure. The pressure is reduced and accelerated in a tapered diffuser section 7 formed downstream of the jet diffuser 6 to form a jet stream.

A supply port 8 is provided at the upper part of the peripheral wall of the diffuser section 7.
The lower end outlet of the hopper 9 is connected to the supply port 8, and the material to be ground in the hopper 9 is supplied from the supply port 8 into the jet stream in the diffuser unit 7, and the material to be ground is It is made to collide with the conical collision surface 4a of the collision member 4 and to be ground by an impact force.

Further, the crushed material is scattered in the radial direction of the collision member 4, and the crushed material collides with a liner 10 provided on the inner periphery of the crushing chamber 3 to perform secondary crushing. I have.

The pulverized material after pulverization is sent to a classifier through an outlet 11 of the pulverizing chamber 3 to be classified into coarse powder and fine powder, and the coarse powder is returned to the hopper 9 and pulverized again. Is the product.

In order to obtain a clear image, a fine toner having a volume average particle diameter of 13 μm or less is preferable for obtaining a clear image, and such a fine toner is obtained. For this purpose, it is necessary to increase the flow velocity of the jet airflow formed in the acceleration nozzle 2 and increase the collision force against the collision member 4.

[0009]

By the way, in the conventional acceleration nozzle 2 for forming a jet stream, the inner surface of the throat portion 6 for increasing the pressure of the compressed gas has a connection portion with the inner peripheral surface at the inlet 5 and a diffuser. Since the compressed gas flows into the throat portion 6, turbulence occurs and energy loss is likely to occur due to the cylindrical shape forming an edge at the connection portion of the tapered inner surface of the portion 6.

The compressed gas that has passed through the throat section 6 is accelerated by expansion in the diffuser section 7 and accelerated to supersonic speed. The diffuser section 7 has a tapered shape expanding to the outlet of the acceleration nozzle 2. Therefore, a shock wave is formed in the vicinity of the supply port 8, and the position of the shock wave becomes an incompressible fluid rather than a compressed fluid from that position, and the flow velocity of the jet stream decreases with an increase in the sectional area of the acceleration nozzle 2.

For this reason, the collision energy of the object to be crushed accompanying the jet stream is reduced, so that the object to be crushed cannot be finely crushed to a minute area, and the crushing efficiency is low.

An object of the present invention is to provide a pulverizing apparatus capable of efficiently pulverizing an object to be pulverized to a minute area.

[0013]

In order to solve the above-mentioned problems, according to the present invention, compressed gas supplied to an inlet is throttled at a throat provided downstream of the inlet and the throat is provided. The material to be crushed is supplied to an acceleration nozzle that expands in a tapered diffuser portion provided on the downstream side of the nozzle and forms a jet airflow, and the material to be crushed is spaced from the outlet of the acceleration nozzle from the tip outlet of the acceleration nozzle. In the crushing device for crushing by colliding with the colliding member disposed oppositely, the inner surface of the throat portion adopts an arc-shaped inner surface that is smoothly continuous with each of the inner surface of the inlet and the tapered inner surface of the diffuser portion. ing.

As described above, when the inner surface of the throat portion is an arc-shaped inner surface, the compressed gas flows smoothly along the arc-shaped inner surface, so that the loss of energy is suppressed, and the flow velocity of the gas in the diffuser portion following the throat portion is reduced. A fast jet stream can be formed, and a large velocity energy can be imparted to the object to be ground entrained in the jet stream.

If a straight section having the same cross-sectional area is provided on the outlet side of the diffuser over the entire length in the axial direction, the flow velocity of the jet airflow formed in the diffuser section can be kept substantially constant, and It is possible to suppress a reduction in velocity energy of the pulverized material. [Detailed description of the invention]

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a pulverizing apparatus according to the present invention.
Since this pulverizing apparatus differs from the conventional pulverizing apparatus shown in FIG. 5 only in the configuration of the acceleration nozzle 12,
The same components are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 2, the accelerating nozzle 12 has an inlet 13, a throat portion 14, a diffuser portion 15, and a straight portion 16, and a supply port 17 for the material to be ground is provided on the upper peripheral wall of the diffuser portion 15. Have been.

The inner surface 14a of the throat portion 14 is
Inner surface 13a and the tapered inner surface 1 of the diffuser portion 15
The shape of the arc is smoothly continuous with 5a.

Here, if the radius of curvature r of the arc-shaped inner surface 14a of the throat portion 14 is too small, the flow of the compressed gas flowing through the throat portion 14 becomes turbulent. The axial length of the portion 14 is increased, the pipe resistance is increased, and the energy loss of the compressed gas is increased. Therefore, the radius of curvature is preferably about 2 to 5 times the radius of the passage in the throat portion 14.

As described above, the inner surface 14 of the throat 14
When a is formed in an arc shape, when the compressed gas supplied to the inlet 13 flows through the throat portion 14, the compressed gas flows smoothly without generating turbulence and flows into the diffuser portion 15.

Therefore, it is possible to prevent the compressed gas from losing energy in the throat portion 14.

When the gas compressed in the throat section 14 flows into the diffuser section 15, it expands, the flow velocity increases, and the state becomes supersonic, and a jet stream is formed. A suction force acts on the supply port 7 by the flow of the jet airflow, and the material to be ground in the hopper 9 is sucked by the diffuser unit 15 and supplied into the jet airflow.

If the diffuser 15 is long enough to reach the outlet of the acceleration nozzle 12, a shock wave is generated on the downstream side of the supply port 17, or the compressed gas expands too much, and the flow velocity of the jet gas flow becomes large. To decline.

However, in the acceleration nozzle 12 according to the embodiment, the straight portion 16 having a uniform cross-sectional area over the entire length in the axial direction is provided on the downstream side of the supply port 17, so that the flow velocity of the jet stream is significantly reduced. Is prevented.

For this reason, the material to be crushed entrained in the jet stream has a large velocity energy, is jetted at a high speed from the outlet of the acceleration nozzle 12 and collides violently with the collision plate 4, and the energy at the time of collision is reduced. Due to their large size, they are very effectively pulverized.

Now, as shown in FIG. 3, three accelerating nozzles having different shapes are prepared, and the accelerating nozzles are assembled in the pulverizing apparatus shown in FIG. 1 to pulverize a toner having an average particle diameter of 30 μm. As a result, the result shown in FIG. 4 was obtained.

Here, the acceleration nozzle (invention I) shown in FIG. 3 (I) shows the acceleration nozzle shown in FIG. 1, and the dimensions of each part are as shown in Table 1.

[0029]

[Table 1]

The acceleration nozzle shown in FIG. 3 (II) (Invention product II)
Indicates an acceleration nozzle having an arcuate inner surface formed in the throat portion and a diffuser portion opened at the nozzle tip, and the dimensions of each portion are equal to those of the acceleration nozzle shown in FIG.

The acceleration nozzle shown in FIG. 3 (III) (conventional product)
5 shows an acceleration nozzle of the pulverizing device shown in FIG. 5, the axial length L ₄ of the throat portion 6 is 10 mm, and the dimensions of the remaining parts are the same as those of the acceleration nozzle shown in FIG. It is the same.

As the pulverization conditions, the pressure P of the high-pressure gas supplied to the supply nozzle 1 is set to P = 6 kg / cm ^2, and the pulverized material discharged from the outlet 11 of the pulverization chamber 3 is separated into coarse powder and fine powder by a classifier. The coarse powder is returned to the hopper 9 and the collected fine powder is collected by a Coulter Multisizer manufactured by Coulter Co., Ltd.
Measured in II.

As is apparent from FIG. 5, the throat portion 14
Nozzle having an arcuate inner surface 14a formed therein (Invention I,
By pulverizing the toner using the invention product II), a pulverized product having a smaller average particle diameter can be obtained than when a cylindrical acceleration nozzle (conventional product) of the throat portion 14 is used.

[0034]

As described above, according to the present invention, the throat portion of the acceleration nozzle is formed with an arc-shaped inner surface that is smoothly continuous with the inner surface of the inlet and the tapered inner surface of the diffuser portion. The turbulence of the compressed gas flowing through the compressed gas can be prevented, and the energy loss of the compressed gas can be reduced.

Therefore, a jet stream having a high flow velocity can be formed in the diffuser section following the throat section, and the object to be crushed accompanying the jet stream can be efficiently pulverized by collision with the collision plate.

Further, by providing a straight portion on the outlet side of the diffuser, the material to be ground can be finely ground.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a crusher according to the present invention.

FIG. 2 is a sectional view showing the accelerating nozzle according to the first embodiment;

FIGS. 3A to 3C are cross-sectional views showing various acceleration nozzles.

FIG. 4 is a graph showing a pulverizing effect of an object to be pulverized using the acceleration nozzle shown in FIGS. 3 (I) to (III).

FIG. 5 is a cross-sectional view showing a conventional crusher.

[Explanation of symbols]

 Reference Signs List 3 crushing chamber 4 collision member 12 acceleration nozzle 13 inlet 14 throat section 15 diffuser section 16 straight section

Claims (2)

[Claims] 1. A compressed gas supplied to an inlet is throttled at a throat provided downstream of the inlet,
The material to be crushed is supplied to an acceleration nozzle that expands in a tapered diffuser portion provided on the downstream side of the throat portion to form a jet airflow, and the material to be crushed is supplied from the tip outlet of the acceleration nozzle to the outlet thereof. In a crushing device that crushes by colliding with a colliding member arranged oppositely at an interval,
A pulverizing device, wherein the inner surface of the throat portion is an arc-shaped inner surface that smoothly continues to each of the inner surface of the inlet and the tapered inner surface of the diffuser portion. 2. The crushing device according to claim 1, wherein a straight portion having a same cross-sectional area over the entire length in the axial direction is provided on an outlet side of the diffuser portion.