JPH074556B2 - Air flow type pulverizing and classifying device for fine powder - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air flow type crushing and classifying device for crushing fine powder used in electronic component materials and the like.

[Prior Art] Conventionally, ceramics and synthetic silica produced by a vapor phase method, a liquid phase method, etc. are ultrafine powders of 1 micron or less, but due to chemi-mechanical coupling, agglomeration of various sizes It becomes a secondary particle (hereinafter referred to as an aggregate). Since the size and the binding force of this fine powder are various, the use of this fine powder as it is in electronic component materials causes quality problems.

Therefore, the development of an apparatus for disintegrating this aggregate into submicron primary particles has been earnestly desired.

An example of this type of device is the airflow type pulverization and classification device proposed by the present inventors, in which solid particles are pulverized by utilizing fluid energy and the pulverized product is collected by an airflow type classification device. (See Japanese Utility Model Publication No. 61-164942).

This will be described with reference to FIGS. 2 to 3. Solid particles are placed in the crushing chamber b via the raw material supply device a, and a predetermined amount of the storage layer c is formed, and the solid particles are positioned near the surface thereof. The jet jet from the fluid nozzle d accelerates the solid particles so that solid particles having velocity energy collide with each other and finely pulverize.

The crushed particles are classified by an air flow classification rotor e,
Along with the air flow, it passes through the fine powder discharge pipe f, is collected by a fine powder collector (not shown), and is taken out as a product from the collector.

Then, when the level of the raw material in the crushing chamber b decreases, the level of the storage layer j is detected by the sensor h inserted into the storage measuring chamber g connected to the side wall of the crushing chamber through the communication hole i to detect the solid particles. To maintain the level at an optimum position and maintain high grinding efficiency.

In the crusher in this case, since the size of the solid particles as a raw material is relatively large, such as several hundreds of microns or less, most of the injected solid particles overcome the jet jet and fall to once form the storage layer c. Is.

[Problems to be Solved by the Invention] However, in the case of crushing agglomerates of powder having a particle size considerably smaller than the size of the solid particles, most of them are dependent on the jet jet speed and the like. , It is disintegrated and suspended by a jet jet and does not form a reservoir layer.

For this reason, even if the agglomerates are supplied in a constant amount and crushed by a crusher, and even if fine powder is obtained through an airflow classifier, the level cannot be detected, so the particle concentration in the crushing chamber fluctuates greatly, Therefore, there is a difference in particle size distribution of the obtained products, and improvement in pulverization efficiency cannot be expected.

On the other hand, in the agglomerates, there is an agglomerate having a relatively large size and a large binding force as described above, which passes through the jet jet without being crushed by the jet jet.
Drop down and collect. Then, when this reaches the jet jet position, the influence of this also causes the fluctuation of the particle concentration.

Therefore, the present invention is based on the finding that the particle concentration is proportional to the static pressure difference between the inside and outside of the classification rotor in the crushing chamber, and greatly suppresses the fluctuation of the particle size distribution and unaggregated aggregates. It is an object of the present invention to provide an airflow type crushing and classifying device which can further improve the crushing efficiency by discharging.

[Means for Solving the Problems] In order to achieve the above object, the airflow type pulverizing and classifying apparatus of the present invention forms a reservoir for storing unaggregated agglomerates in a lower portion of a pulverizing chamber, and the reservoir While connecting the discharger to the lower part of the, a static pressure detector for detecting the static pressure inside and outside the classifier is provided, and this static pressure detector is connected to the particle concentration controller via the static pressure difference converter, A load detector for detecting the rotational load power of the airflow classifier is provided, the load detector is connected to a particle concentration controller, and the raw material feeder is controlled by the particle concentration controller. .

[Operation] The agglomerates introduced into the pulverization chamber are accelerated by the jet jet from the fluid nozzle, and due to this acceleration, the agglomerates are crushed while repeating collision and friction with each other, and become in a floating state.

Then, the fine powder floating from the crushing is classified at a predetermined classification point by an airflow classifier.

On the other hand, among the agglomerates, the agglomerates having a relatively large size and a large binding force have a weak acceleration due to the jet jet, and therefore are not disintegrated and pass through the jets and fall downward to the reservoir. Collect

Here, the static pressures inside and outside the air flow classifier are detected by the respective static pressure detectors and input to the static pressure difference converter, and this static pressure difference is input to the particle concentration controller.

Further, the rotational load power of the airflow classifier is detected by the load power detector, and this is input to the particle concentration controller. The two detected values that have been input, that is, the static pressure difference detected value and the load power detected value are compared and calculated, and based on this result, the raw material quantitative feeder is controlled to control the supply amount of the aggregate.

In addition, the uncrushed agglomerates accumulated in the reservoir are discharged by operating the extruder when the amount exceeds a certain value.

As a result, the crushed fine powder is surely crushed into submicron primary particles, and it is possible to obtain a fine powder without variation.

[Embodiment] An embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an air flow type crusher, which is provided on the upper side wall of a crushing chamber 1a from a raw material bottle 2 to a rotary feeder 3.
The rotary feeder 3 is driven by a drive motor 5 and further has a plurality of fluid nozzles 6 near the lower side wall of the crushing chamber 1a. The fluid nozzles 6 have a high pressure. It is in communication with the fluid generator 7 via a conduit 6a.

Reference numeral 8 denotes a funnel-shaped aggregate storage portion formed in the lower part of the crushing chamber 1a, and a discharge machine 9 is provided at the lower end thereof, and a collection bottle 10 is connected to this discharge machine 9.

Reference numeral 11 is an airflow type classifier installed at the upper end of the crushing chamber 1a, and a classifying rotor 11a of the classifier is rotated at a high speed by a drive motor 12 provided above the crushing chamber 1a.

Reference numeral 14 is a fine powder collector connected to a fine powder discharge pipe 13 provided at the lower portion (discharge side) of the classification rotor 11a, and an exhaust blower is connected to this collector.
Connect 15

16 and 17 are the upper side wall of the crushing chamber 1a and the fine powder discharge pipe 13 respectively.
The static pressure detector provided at the position detects the static pressure inside and outside the classification rotor 11a with reference to the classification rotor 11a. Both detectors 16,17
Is connected to a static pressure difference converter 18, and the static pressure difference converter 18 is further connected to a particle concentration controller 20.

Reference numeral 19 is a load power detector for detecting the rotational load power of the drive motor 12 of the classification rotor 11a, and this detector is connected to the particle concentration controller.

Next, the operation of the embodiment will be described.

Drive motor 5 for agglomerates of fine powder stored in raw material bottle 2
By starting up, the material is cut out from the raw material supply device 3 by a fixed amount, and is introduced into the crushing chamber 1a through the supply pipe 4.

On the other hand, the high-pressure fluid generated by the high-pressure fluid generator is guided to the fluid nozzle 6 via the conduit 6a, and the fluid nozzle 6 causes the high-pressure fluid to flow from the fluid nozzle 6.
While injecting toward the center of 1a, by rotating the drive motor 12 to rotate the classification rotor 11a at high speed, and further start the exhaust blower 15, the agglomerates are entrained in the injected jet jet and accelerated, The particles are crushed while repeatedly colliding and rubbing with each other with velocity energy, and float in the crushing chamber 1a.

The fine powder that has been crushed and suspended as described above is dispensed at a predetermined classification point by the centrifugal force generated by the high-speed rotation of the classification rotor 11a.

The fine powder that has passed through the distribution rotor 11a is guided to the fine powder collector 14 through the fine powder discharge pipe 13 together with the air flow, where it is separated into the fine powder and the air flow, the fine powder is discharged from the lower part as a product, and the air flow is the exhaust blower. It is released into the atmosphere by 15.

On the other hand, fine powder that does not pass through the distribution rotor 11a descends,
It is subjected to the crushing action by the jet jet again.

Further, among the agglomerates, those having a relatively large size and a high strength are weak in the crushing force due to the jet jet and are lowered by their own weight, and are accumulated in the storage part 8, and when the amount exceeds a certain value, the ejector 9 is operated. Collected in collection bin 10.

In the crushing (crushing) classification, the static pressure on the inlet side and the outlet side of the classification rotor 11a is detected by the static pressure detectors 16 and 17, and this is input to the static pressure difference converter 18 and the difference is an electric signal. And input to the particle concentration controller 20. The static pressure difference is proportional to the particle concentration, and the larger the difference, the higher the particle concentration.

Further, the rotational load power of the drive motor 12 is detected by the load detector 19 and input to the particle concentration controller 20. This rotational load power is proportional to the concentration of fine powder (particle concentration) contained in the air flow that swirls around the outer circumference of the distribution rotor 11a, and the particle concentration increases as the load power increases.

Next, in the particle concentration controller 20, the input value is integrated at regular time intervals, the integrated average value and the set value that realizes the optimum concentration state are compared and calculated, and an electric signal corresponding to the difference is output to the drive motor 5. Thus, the number of revolutions is controlled and the amount of the aggregate cut out from the raw material feeder is controlled.

In this way, the particle concentration in the crushing chamber 1a can be maintained in the optimum state, so that the fluctuation of the crushed particle size distribution of the aggregate can be suppressed to be small.

(Example 1) Our company's air flow type fine pulverizer (Product name: Cross Jet Mill)
With a crushing chamber diameter of 110 mm, three nozzles, a distribution rotor outer shape of 50 mm, a distribution rotor rotation speed of 2.1 × 10 ⁴ rpm, a distribution rotor load power of 0.02 KW, and a static pressure difference fluctuation range of 10 mm water column.
The first is the particle size distribution of the fine powder obtained by crushing the raw material (synthetic silica) under optimum crushing (crushing) conditions, that is, 100% particle concentration.
Shown in the table.

(Example 2) The same crusher as in Example 1 was used and the particle size was the same with the same specifications.
Table 2 shows the particle size distribution of the fine powder obtained by crushing the raw material (synthetic silica) under 80%.

(Example 3) The same crusher as in Example 1 was used and the particle size was the same with the same specifications.
Table 3 shows the particle size distribution of the fine powder obtained by crushing the raw material (synthetic silica) under 110%.

The frequency in each table represents the production amount for each sample No (particle size) in%, and the cumulative amount represents the total production amount in which the frequency is sequentially added from the sample No. with the smaller particle shape in%. .

From the results of the above-mentioned examples, what was crushed in Example 1 (particle concentration 100%) was compared with those of other Examples 2 (particle concentration 80%) and Example 3 (particle concentration 110%). Particle size distribution 1.0
The cumulative value of 1 μm or less was as high as 16.8%, and the content ratio of fine powder in the submicron region in the crushed particle size distribution could be increased accordingly.

Incidentally, when the particle concentration of Example 2 is small, the distance between particles is large, and the chances of causing collision and friction between particles are small accordingly, so it is presumed that the crushing action is not sufficient.

Further, when the particle concentration of Example 3 is high, it is presumed that this is due to the outer circumference of the distribution rotor (particles in the centrifugal force field interfere with each other and disturb the distribution effect).

[Advantages of the Invention] Since the present invention is configured as described above, it has the effects described below.

A static pressure detector that detects the static pressure inside and outside the classifier is installed, and this static pressure detector is connected to the particle concentration controller via a static pressure difference converter, and the rotational load power of the airflow classifier is detected. Since the load detector is provided, and the load detector is connected to the particle concentration controller and the raw material supply device is controlled by the particle concentration controller, it is impossible to form the raw material reservoir layer in the grinding chamber. Even in the case of a fine powder pair, the fluctuation of the fineness distribution can be suppressed to an extremely small level, and a fine powder having a predetermined particle size distribution can be easily obtained.

Since a storage part for storing uncrushed aggregates is formed in the lower part of the crushing chamber and an ejector is connected to the lower part of the storage part to discharge the uncrushed aggregates, Stable crushing can be performed for a long period of time without degrading the crushing action due to excessive storage of aggregates.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the device according to the present invention, and FIG.
The figure shows a vertical sectional front view showing a conventional example, and FIG. 3 shows I of FIG.
FIG. 7 is a cross-sectional plan view taken along line I. 1 ... Airflow type crusher, 1a ... Grinding chamber 3 ... Raw material crusher, 5 ... Drive motor 6 ... Fluid nozzle, 8 ... Reservoir 9 ... Discharger, 11 ... Airflow type classifier 12 ...... Drive motor, 16,17 …… Static pressure detector 18 …… Static pressure difference converter, 19 …… Load power detector 20 …… Particle concentration controller

Claims (1)

[Claims] 1. A plurality of fluid nozzles on the side wall of the crushing chamber, an air flow type crusher having a raw material supply port above the fluid nozzles, a raw material supply device connected to the raw material supply port, and an upper part of the pulverization chamber. In an air flow type pulverizing and classifying device for fine powders, which comprises an air flow type classifier provided and a fine powder collector and a blower connected to the discharge side of the classifier, the uncrushed agglomerates are stored in the lower part of the crushing chamber. A reservoir is formed, a discharger is connected to the lower part of the reservoir, and a static pressure detector for detecting static pressure inside and outside the classifier is provided, and the static pressure detector is connected via a static pressure difference converter. A load detector that is connected to a particle concentration controller and that detects the rotational load power of the airflow classifier is provided, and the load detector is connected to a particle concentration controller. Air flow type powder of fine powder characterized by being controlled Classification device.