JPH07275731A - Jet mill - Google Patents

Abstract

PURPOSE:To easily and inexpensively improve the crushing performance of a jet mill by providing an automatic valve which is repeatedly opened and closed on this side of a nozzle for jetting a crushed raw material at high speed along with pressure air and intermittently supplying the pressure air to the nozzle. CONSTITUTION:An accelerating pipe 2 for jetting a granular raw material at high speed is inserted into a casing 1, a raw material feed port 3 and a nozzle 4 are provided in an ejector 2a, and an automatic valve 5, which is repeatedly opened and closed, is connected to the nozzle 4. In this case, one end of the valve 5 is opened, the other end is closed by a cylindrical valve 6, and an open hole 7 is bored in the periphery of the cylindrical valve 6. Further, a rotating shaft 9 and a pulley 10 are furnished to the closed end and connected to a motor 13 through a belt 11 and a pulley 12. The cylindrical valve 6 is rotated and communicated with the nozzle 4, when the open hole 7 is matched with the discharge port 8 of the valve 5. Consequently, the pressure air is intermittently discharged, and the crushing performance of the jet mill is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jet mill for finely pulverizing powdery or granular material.

[0002]

2. Description of the Related Art A jet mill accelerates a granular material (hereinafter, simply referred to as "material") at high speed with pressurized air,
The raw materials are crushed by colliding with each other or with a collision plate provided separately. As a conventional jet mill type, a type in which the accelerating tubes for accelerating and injecting the raw material are arranged to face each other and the raw materials collide with each other, and a type in which the raw material injected from the accelerating tube collides with a collision plate or the like ,
For example, there is a container in which an accelerating tube is inserted and arranged in a container in which raw materials circulate. In addition, the jet mill uses air instead of mechanical force such as impact, shearing, compression, and grinding by crushing blades and compression rolls, and also has a cooling effect with less heat generation of raw materials and low melting point substances such as synthetic resins. It is also advantageous for the crushing of various types of materials, and is also used for crushing various kinds of materials.

[0003]

By the way, the jet mill has a very simple structure because it can be pulverized by supplying raw material and pressurized air. However, it consumes a large amount of air, and the energy efficiency with respect to the pulverizing capacity is different from that of other jet mills. The disadvantage is that it is lower than the crusher. The reason for this is that the raw materials are accelerated by the pressurized air and collide with the collision plate, or the raw materials collide with each other. At that time, in the part where the raw materials collide (hereinafter referred to as the collision surface), the air together with the raw material collides with the collision surface. Will be hit. As a result, a layer of air is created on the surface of the collision surface, which may reduce the velocity of the raw material accelerated by the nozzle before it hits the collision surface, weakening the impact force at the time of collision. To be

Therefore, for example, in the case of a jet mill of the type in which the raw material is jetted together with the pressure air to collide with the collision plate to be crushed, the collision plate with respect to the accelerating pipe for injecting the raw material is inclined, or is conical or umbrella-shaped. There is one that makes it easier for air to flow from the center toward the outside. However, even if these effects are more or less than the conventional ones, they are still insufficient in terms of energy efficiency with respect to air consumption.

In view of the above points, the present invention enables a raw material accelerated by a nozzle by pressurized air to collide with a collision surface without reducing the speed of the raw material, thereby efficiently pulverizing the material. Is.

[0006]

According to the present invention, a valve that automatically repeats opening and closing is provided in front of a nozzle for injecting pressure air, and the pressure air is intermittently supplied to the nozzle. This is because the pressure air is injected intermittently, and the operation is as follows.

[0007]

In the conventional jet mill, the injection of the pressurized air from the nozzle is continuously performed. Therefore, the air hitting the collision surface forms a layer of air in the vicinity of the collision surface, which also causes the collision speed of the raw material injected later to be weakened and the impact force to be reduced. On the other hand, by intermittently injecting the pressurized air from the nozzle, the mixed air flow of the raw material and air (hereinafter referred to as the raw material flow) is also intermittently ejected, and it is intermittent to the collision surface. Will collide with each other.

As a result, what was conventionally continuously injected is intermittently injected, so that the preceding raw material stream collides with the collision surface so that the collision occurs intermittently on the collision surface, Until the next raw material stream reaches the collision surface (within the moment when collision does not occur), the raw material stream that previously hit the collision surface moves quickly from the collision surface, and then the next raw material stream. When a new raw material flow collides with the collision surface, the raw material flow that has already collided does not stop near the collision surface. As a result, the impact force when the raw material flow collides with the collision surface is not weakened or obstructed, and the raw material is always crushed with a sufficient impact force corresponding to the injection speed of the nozzle. .

Further, by intermittently injecting pressurized air from the nozzle, a shock wave is generated near the tip of the nozzle, or a pulsating action occurs. Further, the ejector action causes a rapid pulsation of suction and acceleration of the raw material. Because of this, the collision and friction of the raw materials occur violently even in the raw material flow before reaching the collision surface, and the pulverization of the raw materials is promoted. As a result, the crushing action is increased, finer crushing is possible than in the past, and the crushing ability can be improved.

[0010]

As described above, according to the present invention, the crushing force can be increased and the fine crushing and the crushing ability can be greatly improved with a simple structure in which the pressurized air is intermittently jetted from the nozzle. Moreover, by intermittently injecting the compressed air, the consumption of the compressed air can be reduced and the energy efficiency with respect to the crushing capacity can be improved.

[0011]

EXAMPLE An example of the present invention will be described below with reference to FIG. An accelerating tube 2 inserted in a casing 1 of a jet mill and for injecting raw material powder particles at a high speed includes an ejector unit 2 for sucking and conveying the raw material by pressurized air.
a and a straight pipe portion 2b for accelerating the raw material, and the ejector portion 2a is provided with a raw material supply port 3 and a nozzle 4 connected to a pressure air source (not shown).
A valve 5 capable of automatically repeating opening and closing is connected to the nozzle 4.

The valve 5 has an opening 7 penetrating toward the peripheral portion of a cylindrical valve 6 having one end open and the other end closed, and a rotary shaft 9 and a pulley 10 are attached to the closed end. It is connected to a motor 13 via a belt 11 and a pulley 12. Then, the cylindrical valve 6 is rotated to rotate the cylindrical valve 6
When the side opening 7 and the discharge port 8 of the valve 5 are aligned with each other, communication with the nozzle 4 is performed, and by continuously rotating the cylindrical valve 6, the pressurized air is intermittently sent to the air nozzle 4. be able to. That is, the interval of intermittent supply of the pressurized air to the nozzle 4 can be easily set by adjusting the number of rotations of the rotating shaft 9, for example, once in several seconds to 10 in one second.
It can be arbitrarily set up to about 00 times.

The straight pipe portion 2b of the accelerating pipe 2 has a length sufficient for accelerating the raw material by pressurized air and injecting it at a high speed, and its inner passage has a surface for preventing deceleration due to friction. Is smooth, and the opening slightly expands toward the tip.

A collision plate 14 is arranged in front of the tip of the acceleration tube 2 with an appropriate interval. The collision surface 15 of the collision plate 14 has a high center and is formed in a smooth conical shape with a slight inclination toward the outer side, and the air colliding with the collision surface 15 has a collision surface 1
It smoothly flows from 5 to the outside and is quickly removed from the collision surface 15. Further, a cylindrical annular guide member 16 for smoothly flowing the raw material and the air from the collision surface 15 rearward is arranged on the outer peripheral side of the collision plate 14 with an appropriate interval. The guide member 16 is connected to the collision plate 14 via a bracket 17, and the bracket 17 itself is attached and held by a support member 18. The support member 18 is attached and fixed to the casing 1 of the jet mill body. Further, in this embodiment, the supporting member 18 also serves as a spacer that determines the distance between the accelerating tube 2 and the collision plate 14, and by changing the length thereof, the accelerating tube 2 and the collision plate 14 and The distance from the collision surface 15 can be changed arbitrarily.

Further, the raw material that has collided with the collision plate 14 is sent to an airflow classifier (not shown) for classification and classification, and fine powder is sent to a collector such as a cyclone or a bag filter to be collected to obtain a coarse powder. Are collected, transported, mixed with a raw material for pulverization, and fed again to the acceleration tube 2.

[0016]

[Experimental Example] In an experiment using cold water stone having a particle size of 1 to 2 mm as a raw material, comparing the crushing results when continuously injecting pressurized air and when intermittently injecting, the nozzle 4
When the caliber is 4.2 mm, the amount of fine powder collected as a product and its average particle size are 3.0 K when continuously jetted.
The average is 4.2 μm in g / Hr, and the average is 3.5 μm in 4.5 kg / Hr when injected intermittently at 60 times / second.
Thus, better results were obtained with intermittent injection than with continuous injection. Regarding the consumption of compressed air, 1.
In contrast to 0 Nm ³ / min, in the case of intermittent injection, it was 0.75 Nm ³ / min, and the consumption of compressed air was also reduced.

[0017]

[Another embodiment] The distance between the acceleration tube 2 and the collision plate 14 is
It is also possible to freely change the length of the support member 18 by changing the length or by changing the mounting method of the collision plate 14 to the support member 18. Also, the acceleration tube 2
The shape of the nozzle 4, the size of the opening, and the like can be arbitrarily changed according to the type and particle size of the raw material. Further, the surface of the collision plate 14 may be subjected to abrasion resistance treatment or an abrasion resistant material may be attached thereto, and the collision plate 14 itself may be constituted by an abrasion resistant material. Can also be changed.

The cylindrical valve 6 of the valve 5 may be provided with a plurality of openings 7, and the rotational driving method of the cylindrical valve 6 may be a chain or gear instead of a belt, and a motor with a speed reducer may be used as a rotary shaft. You may make it connect directly to 9. Further, in addition to tapering the cylindrical valve 6, a piston type is used to change from rotational movement to reciprocating movement, a disc type is used to rotate, and a discharge port 8 of the valve 5 is provided via a cam or the like. A general valve type for opening and closing may be used. Furthermore, in addition to incorporating an ultrasonic motor, using a solenoid valve, all types of valves that open and close automatically are applicable. In addition, in the present invention, not only a normal valve but also a reed valve, a floating spindle, or the like that causes pulsation in the pressure air flow supplied to the nozzle 4 by operating itself by the flow rate or pressure fluctuation. Is also included.

Further, the present invention is not limited to the type in which the raw material is collided with the collision plate and crushed, but the type in which the accelerating pipes 2 are opposed to each other and jetted to collide the raw materials with each other as shown in FIG. In addition to the above, it is also possible to implement a type in which the acceleration tube 2 is not provided and only the nozzle 4 is configured. For example, as shown in FIG. For example, by injecting or injecting the raw material into the crushing chamber B storing the raw material as shown in FIG. The present invention can be applied to all known jet mills such as a method of crushing raw materials by colliding them.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

[0021]

FIG. 1 is a cross-sectional view of a main part of this embodiment.

FIG. 2 shows another embodiment.

FIG. 3 shows another embodiment.

FIG. 4 shows another embodiment.

[0022]

[Explanation of symbols]

 1 casing 2 acceleration pipe 2a ejector part 2b straight pipe part 3 raw material supply port 4 nozzle 5 valve 6 cylindrical valve 7 opening hole 8 discharge port 9 rotary shaft 13 motor 14 collision plate 15 collision surface 16 guide member 17 bracket 18 support member A grinding Room B Grinding room

Claims (2)

[Claims] 1. A valve 5 which automatically repeats opening and closing is provided in front of a nozzle 4 for injecting a raw material powder and granules together with pressurized air at a high speed so that the pressurized air is intermittently supplied to the nozzle 4. A jet mill characterized by being configured. 2. The nozzle 4 is attached to an accelerating pipe 2 having a raw material supply port 3, an ejector portion 2a and a straight pipe portion 1b, and a collision plate 14 is provided in front of the tip of the accelerating pipe 2.
The jet mill according to claim 1, wherein the collision surface 15 of the collision plate 14 is formed in a cone or an umbrella shape having a high inclination or a high center.