JPH02207852A - Pulverizer - Google Patents

Abstract

PURPOSE:To enhance efficiency of comminution by constituting a fine grinding mill so that a supplied raw material for pulverization can be ground to powder narrow in the width of particle size distribution without exceeding limiting particle size. CONSTITUTION:A crushing means 2 is constituted of a rotary disk 9 fixed to a first driving shaft 8, a purality of joining members 12 held to the rotary disk 9, two pieces of annular disks 13, 14 fixed to both ends of the joining members 12 and necessary pieces of blade plates 15 held to the annular disks 13, 14. Further the inner surface of a classification chamber C is formed into an oblique wall face narrowed according to approach to a carrier chamber D. A cylindrical rotary impeller 3 is provided to the inside of the chamber C and held to a second driving shaft 30. Further many strip-form blades are formed to the outer circumferential face of the impeller 3. Furthermore an annular air reservoir 39 is provided to the boundary of the classification chamber C and the carrier chamber D. This reservoir 39 is connected to the outside and also connected to both the chamber C and the carrier chamber D via the prescribed gaps 40, 41.

Description

[Detailed description of the invention] (Industrial application field) This invention relates to a fine grinder, mainly for ores.

It is used to crush solid materials such as ceramics and foods to create fine powder with a narrow particle size distribution (from around 100 μm to several μm).

(Prior art) As a conventional device of this kind, for example,
Those disclosed in Japanese Utility Model Publication No. 695 and Japanese Utility Model Publication No. 60-39081 are known.

In the devices disclosed in these publications, the powder pulverized by the pulverizing rotor is carried by an air stream and passed along a truncated conical guide plate with a large diameter at the upper end between the pulverizing rotor and a co-receiving classification impeller. carried towards the top of the

In the classification impeller, only the fine powder in the pulverized powder is passed through the impeller by the airflow from the exhaust fan and moved to the exit side of the device. However, the coarse powder in the powder that does not pass through the impeller descends along the inside of the guide plate, passes under the lower end of the guide plate and is moved outward, and is again subjected to the crushing action by the crushing rotor.

In these devices, the fine powder and coarse powder in the powder are classified by pulverizing the coarse powder, which is greatly affected by the centrifugal force of a rotating impeller, while repeatedly circulating it up and down along a truncated cone-shaped guide plate. The powder is pulverized by a rotor, and the fine powder in the powder is placed in the airflow of an exhaust fan against the centrifugal force caused by the rotation of the impeller, and the suction action is used to guide it inside the impeller. The desired particle size of the powder taken out from the device by the classification action was obtained by changing the air volume of the blower and the centrifugal force caused by the rotation of the impeller.

(Problems to be Solved by the Invention) In the conventional device described above, since the airflow carrying the powder flows into the impeller from the upper large diameter part of the impeller, the passing speed of the airflow is lower in the lower small diameter part of the impeller. It is slow and the carrying force of the airflow on powder particles is small. On the other hand, since the centrifugal force caused by the impeller is proportional to its radius, the lower diameter of the impeller can be made smaller, and for the same powder particle size, the conveying force C due to the airflow and the impeller at any position on the impeller can be reduced. Care was taken to ensure that the relationship between centrifugal force F due to the car was the same.

However, if the set flow rate of the passing airflow changes, not only will the rate of reduction in the passing velocity along the blade differ, but this rate of reduction will not necessarily match the rate of reduction in the radius of the impeller. Therefore, for a certain air volume, the value of centrifugal force F/conveying force C can be made almost the same for the entire length of the impeller, but for any air volume, for the entire length of the impeller, It is practically impossible to always desire the same centrifugal force F/conveying force C. For this reason, there are disadvantages in that not only the critical particle size corresponding to the sieve mesh differs at both ends of the impeller, but also the particle size distribution width of the pulverized powder obtained at the exit of the device becomes wide.

In addition, in the gap between the upper end of the impeller and the housing, as a matter of course, the blade is missing, so an obstacle such as a hanging flange is provided on the housing. Since this is a shortcut for the airflow passing through, the passing speed does not match the design wind speed, and the action of centrifugal force on the powder particles is smaller than at other locations. For this reason, particles that are larger than the intended particle size limit and are commonly referred to as black particles may be mixed into the fine powder from this portion, degrading the quality of the fine powder.

This invention was made in view of the problems of the prior art, and its purpose is to reduce the particle size of the supplied raw material for pulverization without exceeding the particle size limit, and with a narrow particle size distribution. It is an object of the present invention to provide a fine grinder that can grind into powder and has high grinding efficiency.

(Means for Solving the Problems) In order to achieve the above object, in the model device of the present invention, the raw material for crushing that is supplied to the crushing chamber together with suction air from the air supply port is crushed by a rotary crushing means. Then, the fine powder of a certain particle size or less in the pulverized material that is air-transported to the next classification chamber is taken out of the apparatus by an exhaust fan connected to the transfer chamber through the intake passage of a rotary impeller installed in the classification chamber, and the fine powder In a pulverizer that repeatedly crushes other coarse particles by returning them to the pulverizing means side using centrifugal force acting on the pulverizing means, the pulverizing means includes a rotating disk fixed to a first drive shaft, and a peripheral portion of the rotating disk. A plurality of coupling members held at right angles, two annular disks fixed to both ends of the coupling members in parallel with the rotating disk, and a required portion held by these annular disks and protruding outward. The inner surface of the classification chamber is formed by an inclined wall surface sandwiched between the conveyor chambers, and a rotary impeller held by a second drive shaft is installed in the center of the chamber. It has a cylindrical shape with a closed end face on the means side, and has a large number of rectangular blades formed in the axial direction on the outer circumferential surface, and the inclined wall surface of the classification chamber is close to the outer circumferential surface of the rotary impeller at the boundary with the transfer chamber. An annular air pocket communicating with the outside is provided on the inner circumferential surface, and the air pocket is connected to the classification chamber and the transfer chamber by a primary side gap and a secondary side gap in opposite directions formed between the rotating impeller and the rotating impeller. It was designed so that

In order to take out the pulverized fine powder with a high yield, the primary gap that connects the air reservoir and the classification chamber is larger than the secondary gap that connects the air reservoir and the transfer chamber, and the gap size is larger in the length direction of the rotary impeller. It is preferable to form it with short dimensions.

In order to make the pulverizer vertical, the pulverizing means and the rotary impeller are each provided with a vertical first pulverizer. A grinding material supply device is attached to the second drive shaft and faces the outer peripheral surface of the rotary impeller on the inclined wall of the classification chamber, and a horizontal intake passage is provided below the grinding means. You can.

(Function) When the raw material for pulverization is supplied and the device is operated, a pulverizer equipped with a vane plate rotated by one drive shaft, a rotary impeller rotated by the other drive shaft, and a transfer chamber are connected. A conveying airflow from the air supply port toward the conveyance outlet is formed in the internal space of the device by the exhaust fan. The raw material for pulverization supplied to the pulverization chamber is conveyed to the periphery of the rotating disk by the conveying air flow, where the raw material is pulverized by colliding with the blades and the peripheral wall of the pulverization chamber.

The powder after pulverization is carried by a conveying airflow blown out from between the peripheral edge of the annular disk and the inner wall of the crushing chamber toward the periphery of the classification chamber in the direction of the drive shaft, and is transported by the inclined inner wall surface of the classification chamber. It is deflected and distributed almost uniformly over the outer peripheral surface of the rotary impeller. Further, the speed of the conveying airflow passing through the intake passage provided on the outer circumferential surface of the rotary impeller is also substantially uniform. Therefore, on the outer circumferential surface of the rotary impeller, the velocity in the radial direction of the impeller through which the carrier airflow passes is substantially uniform in both the axial direction and the circumferential direction.

The powder in the classification chamber is subjected to both the suction action into the rotary impeller by the conveying airflow and the centrifugal action by the swirling airflow of the rotary impeller. However, the suction action is stronger on the fine particles in the powder, and the centrifugal action is stronger on the coarse particles in the powder. However, coarse particles cannot move into the rotary impeller, and the pulverized powder is classified at a critical particle size determined by the performance and operating conditions of the device.

Coarse particles that cannot be moved into the rotary impeller are moved to the periphery of the crushing means by the suction action of the blades of the crushing means.
Since the particle size is repeatedly pulverized until the particle size falls below the limit particle size, the particle size distribution width of the powder obtained at the outlet of the apparatus becomes narrow.

Furthermore, the air pocket is connected to a pressurized air source or to the outside, so the pressure is higher than or almost equal to atmospheric pressure, and the classification chamber and transfer chamber have negative pressure due to the rotation of the rotary impeller and exhaust fan. During operation, air flows from the entire circumference of the annular air pocket into the primary gap through the secondary gap. Therefore, the powder that has been moved to the outer circumference of the rotary impeller does not enter the secondary gap, and the fine powder that has been transferred to the transfer chamber is prevented from entering the secondary gap.

(Embodiment) FIGS. 1 to 4 show an embodiment of the present invention.

As shown in FIG. 1, the main body case includes a supply chamber A1 equipped with a supply device l connected to an air supply port 50, a crushing chamber 81 housing the crushing means 2, a classification chamber C1 housing the rotary impeller 3, and a transport outlet. 4 and a transfer chamber connected to an exhaust fan, and at the outer central portions of the supply chamber and the transfer chamber, bearing cases 5 and 6 projecting in the horizontal direction are located at their flange portions 5a.

The overlapping portion of 6a is screwed.

Reference numeral 8 denotes a horizontal first drive shaft supported by bearings 7, 7 in the bearing case 5. One end of the first drive shaft 8 projects to the crushing chamber B, and the other end extends outside the bearing case 5. It is protruding towards the side. A boss portion 9a of a rotary disk 9 constituting the crushing means 2 is integrally connected to the first drive shaft 8 in the crushing chamber B by a key 10, and the rotary disk 9 is connected to a small diameter portion at the tip of the first drive shaft 8. Movement of the first drive shaft 8 in the axial direction is prevented by a nut 11 which is threadedly engaged with a male threaded portion formed in the first drive shaft 8.

The other end of the first drive shaft 8 protruding outward from the bearing case 5 is connected to a drive motor (not shown) that rotates the crushing means 2 via a speed reduction means.

The crushing means 2 includes a rotating disk 9 attached to the first drive shaft 8, a plurality of, for example, eight, coupling members 12 that protrude in the radial direction and intersect at right angles to the peripheral edge of the rotating disk 9. Two annular disks 13 and 14 parallel to the rotating disk 9 are fixed to both left and right ends of the coupling member 12, and these annular disks 1
This is a so-called turbo-type impeller, which is composed of a required number of vanes 15 that are held on the periphery of a 3.14 blade and protrude outward, and has the ability to exert a powerful fan effect when rotated.

The rotating disk 9 attached to the first drive shaft 8 is positioned by a spacer 16 attached to the first drive shaft 8, and in front of the inner peripheral surface of the device body, there is a gap δ1 between the tip of each vane plate 15. The toothed lining member 17 is inserted so as to maintain a set value (for example, around 1 mm) and maintain a set gap δ2 (for example, around 10 m+n) with the outer peripheral surface of the annular disk 14. An annular cooling jacket 1 is provided between the outer circumference of the lining member 17 and the inner circumference of the device body.
8 is formed. On the side surface of the supply chamber A side of the grinding chamber B, an annular side lining member 19 is provided which faces the annular disc 13 and the blade plate 15 and abuts against the toothed lining member 17.
is installed.

The rotary disk 9, the coupling member 12, the annular disks 13, 14, and the vanes 15 can be connected, for example, by the configuration shown in FIG.

That is, a plurality of coupling members 12 are fitted into notches 9a provided at intervals on the periphery of the rotating disk 9, and fixed by welding or other means. An annular disk 13 is fixed to the supply chamber A side end of the coupling member 12 that intersects the rotating disk 9 at right angles by means such as welding. This annular disc 13 has an inclined surface 13c formed at the lower end of the inner surface, the thickness of which becomes thinner toward the inner peripheral surface, and an annular cutout 13a of a constant depth at the upper end of the outer surface. Circular cutout 1 on the surface
A required number of radial outer peripheral notches 13b extending beyond the lower side of 3a are provided.

Next, an annular disk 1 is attached to the end of the coupling member 12 on the classification chamber C side.
An annular disc 14 having an annular notch 14a corresponding to case 3 and an outer peripheral notch 14 is fixed by means such as welding. The inner peripheral side of one annular disk 13 has an inclined surface 13
The other annular disk 14 is fixed in a position partially facing the outer circumferential side of the rotating disk 9 at the part c, but has the same outer diameter.
does not have a portion corresponding to the inclined surface 13C, and the inner diameter thereof is larger than the inner diameter of the annular disk 13,
The inner circumferential surface is fixed so as to be located slightly outward from the outer circumference of the rotating disk 9.

In the annular disc 13, a first ring 20 of a constant thickness is fitted into an annular notch 13a on the outer periphery, and this 117th ring 20
is fixed to the annular disk 13 by welding or other means.

In each of the outer circumferential notches 13b and 14b provided at the corresponding positions of the annular disk 13 and 14, a blade plate 15 having rectangular notches 15a and 15a at both left and right ends is inserted from the classification chamber C side. It is inserted laterally, and one notch 15a is engaged with the first 'J ring 20. Then, the second ring 21 is fitted into the annular recess formed by the annular notch 14a of the other annular disc 14 and the notch 15a of each vane plate 15, and is screwed to the annular disc 14. The blade plate 15 can be replaced. The blade plate 15 protrudes due to the centrifugal force caused by the 20 revolutions of the crushing means. This is prevented by engagement with the second ring 20.21.

Note that each blade plate 15 may be attached using other configurations. That is, as shown in FIG.
3.14 each outer circumference notch 13b.

Cylindrical notches 13bl and 14bl, which are slightly larger than the width dimensions thereof, are formed at the tips of the blades 14b, and cylindrical notches 13b1 are formed on both sides of each blade plate 15 on the drive shaft side.
．． The first ring 20 and the second ring 21 form cylindrical protrusions 15b, 15b that engage with the annular disk 13. This is a case where separation of the two is prevented. In this case, the protrusion of the blade plate 15 due to the centrifugal force accompanying the rotation of the crushing means 2 is caused by the engagement between the cylindrical protrusions 15b, 15b of the blade plate 15 and the cylindrical cutout 13b1.14bl of the annular disk 13.14. This is prevented by

In the supply chamber A above the drive shaft 8, there is provided a supply device 1 having a feed screw in a direction perpendicular to the drive shaft 8. Not driven by a motor, the feed hopper (
(not shown) is supplied to the grinding chamber B. An annular air pocket 23 is formed at the overlapping part of the spacer 16 that contacts the bearing 7 and the front cover 22 that fits into the spacer and closes the inner opening of the bearing case 5. The supply chambers on both sides are communicated with a space inside the bearing case 5, and are also communicated with a pressurized air source or the outside air through a ventilation path 24 provided in the bearing case 5. and 5 are outer cover plates attached to the opening of the bearing case 5.

Therefore, during operation, air flows from the air reservoir 23 communicating with the pressurized air source or the outside air to the supply chamber A side, which is in a negative pressure state and has a lower pressure than the outside air, and the powder in the supply chamber A is transferred to the spacer. Since powder is prevented from entering the gap between the powder 16 and the front cover 22, various troubles that may occur if powder enters are prevented.

The rotary impeller 3 provided in the center of the classification chamber C has a hollow cylindrical shape, and a large number of rectangular blades 26 are provided along the circumference at a set center angle and parallel to the axial direction on its outer peripheral surface. An intake passage 27 passing through the outer peripheral surface of the rotary impeller 3 is formed between the adjacent blades 26 and 26. The rotary impeller 3 has a portion extending into the transfer chamber that is integrally connected to several stay plates 29 that protrude from a conical boss portion 28, and a horizontal second drive that protrudes from the bearing case 6. A key 31 that engages with the boss portion 28 on the base end side of the shaft 30
are integrally connected by. Further, the opening at the tip of the rotary impeller 3 on the side of the crushing chamber B is blocked from communicating with the side of the crushing chamber B by a circular closing plate 32 .

The rotary impeller 3 has a positioning spacer inserted between the boss portion 28 of the rotary impeller 3 and the bearing 34 in the bearing case 6 by a bolt 33 that screws the blocking plate 32 to the end face of the second drive shaft 30. 35 and is pressed against the inner ring of the bearing 34.

A part of the inner wall surface of the classification chamber C is horizontal on the side near the crushing means 2, and the middle part is a conical surface with a small diameter inclined at an angle of about 45 degrees toward the transfer chamber side, and is adjacent to the transfer chamber side. The side facing the building is a horizontal part with a step. The horizontal portion having the step has an inner surface connected to the conical surface of the classification chamber C and curved toward the intake passage 27 of the rotary impeller 3, and a transfer chamber adjacent to the outer peripheral surface of the rotary impeller 3. A conical cover 36 is fixed to a partition wall 38 between the transport chamber and the transfer chamber by bolts 37.

The conical cover 36 has an annular air pocket 39 formed in a portion of the inner circumferential surface that fits with the outer circumferential surface of the rotary impeller 3 . The air pocket 39 has a radial dimension δ3 formed between the outer peripheral surface of the rotary impeller 3 and the inner peripheral surface of the conical cover 36.
The primary side gap 40 communicates with the classification chamber C side, and the opposite side of the air pocket 39 is conveyed through a secondary side gap 41 with a radial dimension δ4 (δ4<δ,) formed in the same way. It is connected to the room side. -Length 1 of the next side gap 40
3 is determined to be slightly shorter than the length I14 of the secondary side gap 41.

An annular closed space 42 formed on the transfer chamber side of the conical cover 36 is connected to a communication path 43 provided in the conical cover 36.
It is connected to the air reservoir 39 by the air reservoir 39, and is also connected to the outside of the device by a communication path 44 provided in the main body of the device.

Therefore, the air in the air reservoir 39, which is in communication with the pressurized air source or the outside air, is constantly blown out through the primary side gap 40 and the secondary side gap 41 into the classification chamber C and the transfer chamber, which are under negative pressure during operation. Preventing powder in the airflow before classification from entering into the rotating part gap between the rotary impeller 3 and the conical cover 36,
This prevents the powder from short-circuiting to the transfer chamber.

The maximum diameter of the stay plate 29 is determined to be close to the minimum cross section of the spirally formed transfer chamber, and the inner opening of the bearing case 6 is connected to the rear cover 45 which fits into the outer periphery of the spacer 35. is blocked by. Bearing 34
An annular air pocket 47 is provided at the overlapping portion of the spacer 35 and the rear cover 45 facing each other, and the annular air pocket 47 communicates with a pressure air source or the outside air through a ventilation path 46.
is connected to the transfer chamber by a sealing gap 48 formed between the outer periphery of the spacer 35 and the inner periphery of the rear cover 45. Therefore, during operation, air sealing is performed by air flowing out through the ventilation path 46, air reservoir 47, and sealing gap 48 in the transfer chamber under negative pressure, and the fine powder in the transfer chamber is removed from the transfer exit. 4 is taken out from the transfer chamber by an unillustrated exhaust fan connected to 4.

The second drive shaft 30 protruding outward from the outer cover plate 49 of the bearing case 6 is connected to a motor (both not shown) via a speed reduction means.
The crushing means 2 is connected to the crushing means 2 and can be rotated separately from the crushing means 2.

Next, the operation of the device will be explained.

When each motor of the pulverizer is driven to put the device into operation, the raw material for pulverization supplied to the supply chamber A by the feed screw of the supply device L is transferred to the supply chamber A side by the suction airflow formed in the device. It is conveyed to the inner circumferential wall side of the grinding chamber B along the rotating disk 9 through the central opening of the annular disk 13,
A large number of rotating vanes 15 and toothed lining member 1
7.

The pulverized material pulverized by the pulverizing means 2 passes through the peripheral gap δ2 formed by the outer diameter of the annular disk 14 on the classification chamber C side and the inner diameter of the toothed lining member 17, and flows in the direction of the drive shaft. As a result, it moves to the peripheral wall of the classification chamber C.

The pulverized material in the classification chamber C is turned in the radial direction of the rotary impeller 3 by the suction airflow moving along the inner wall surface having an inclination angle of about 45 degrees.

The pulverized material in the classification chamber C is processed by a rotary impeller 3 using suction airflow.
Both the inward suction force and the centrifugal force due to the swirling airflow around the rotary impeller 3 act, but in the vicinity of the rotary impeller 3,
The suction force is greater than the centrifugal force for fine particles in the pulverized material, and the centrifugal force is greater than the suction force for coarse particles in the pulverized material. Therefore, among the crushed materials traveling in the radial direction of the rotary impeller 3, only the fine particles ride the suction airflow and move into the rotary impeller 3 from the intake passage 27 between the blades 26, supporting the rotary impeller 3. The powder passes between the staple plates 29 and is transported from the transport outlet 4 to a fine powder extraction device (not shown).

On the other hand, coarse particles in the pulverized material are moved away from the rotary impeller 3 by the action of centrifugal force. The separated coarse particles are carried by the suction action of the turbo-type impeller of the crushing means 2 from between the outer periphery of the rotary impeller 3 and the central opening of the annular disk 14 to the periphery of the vane plate 15. The pulverizing action is repeated until the particle size falls below the size that can be sucked into the rotary impeller 3.

In this case, the rotating disk 9 of the crushing means 2 separates the circulating airflow from the primary airflow that conveys the raw material for crushing to the periphery of the crushing means 20 so that they do not interfere with each other. The coarse particles conveyed in the opposite direction are repeatedly crushed without delay to improve the crushing efficiency.

Moreover, in the classification chamber C, the airflow path from the gap δ2, which is the outlet of the crushing chamber B, to the throat part around the boss part 28 inside the rotary impeller 3 is closer to the crushing chamber B, and when the airflow path is closer to the conveyor chamber. Since the pressure loss is almost the same even in the case where there is no significant difference in magnitude, the intrusion speed of the airflow containing fine powder passing through the intake passage 27 of the rotary impeller 3 is as follows in the length direction of the intake passage 27 be equal. Further, the airflow velocity in the circumferential direction of the rotary impeller 3 is kept almost constant due to the rotation of the several stay plates 29.

However, it is known that the force with which the conveying airflow draws particles into the rotary impeller 3 is proportional to the product of the outer circumferential length of the particles and the airflow velocity.
The critical particle diameter that can be drawn into the interior of the intake passage 27 can be made the same throughout the length of the intake passage 27.

Therefore, according to the apparatus of this embodiment, the particle size distribution width of the particles taken out from the conveyance outlet 4 is narrower than in the conventional case where the critical particle diameter changes in the length direction of the blade, and uniform fine powder can be obtained. be able to.

In addition, inside the device which is in a negative pressure state during operation, there is a pressure air source or an air pocket connected to the outside air.
Air flows out from 7 to the space through which the airflow that transports the powder passes and acts as an air seal, preventing the pulverized material from entering the gap between the rotating parts and transporting the powder in the airflow before being classified. It is possible to prevent short circuits from entering the room, and to reduce the occurrence of troubles in the bearings 7, 34.

Of these, in the air pocket 39 that performs air sealing for both the classification chamber C and the transfer chamber, the amount of air flowing out through the primary side gap 40, which has a large gap size and a short length, has an opposite dimensional relationship. The amount of air flowing out from the secondary side gap 41 is larger than the amount of air flowing out from the secondary side gap 41. And, the air seal in the -next side gap 40 is
The secondary side gap 41 prevents coarse particles larger than the limit particle diameter in the classification chamber C from moving to the transfer chamber side, prevents the expansion of the particle size distribution width, and improves the quality of the product. The fine powder transported to the chamber is prevented from returning to the classification chamber C to prevent the classification efficiency from decreasing.

Further, since the crushing means 2 and the rotary impeller 3 are driven separately, by adjusting the rotation speed of both, it is possible to efficiently obtain a product having a desired particle size and particle size distribution width.

FIG. 6 shows another embodiment of the present invention, in which the crushing means 2 is attached to a vertical first drive shaft 8A, and the rotary impeller 3 is attached to another vertical second drive shaft 30A.
Grinding raw material supply device I equipped with a feed screw facing the circumferential side of the rotary impeller 30 on the inclined wall surface of the classification chamber C
A is provided, and a horizontal air supply port 50 is provided below the crushing means 2 to form a vertical device. In FIG. 6, the same reference numerals as in FIG. 1 indicate the same components as in FIG. 1.

In this configuration, part of the fine powder in the raw material for pulverization supplied from the supply device IA is directly sucked into the rotary impeller 3 by the suction airflow, but the The raw material for pulverization supplied to is pulverized into fine powder through the same pulverization process and classification process as described for the horizontal type in the above embodiment. The obtained effects are almost the same as those described in the previous embodiment.

(Effects of the Invention) Since the present invention is configured as described above, it produces the following effects.

(1) The airflow carrying the pulverized material from the pulverizing means is directed in the radial direction of the rotary impeller by the inner wall surface of the classification chamber with an inclination angle of around 45 degrees, and is directed in the length direction of the impeller with approximately the same flow velocity. Because they are uniformly dispersed, in the vicinity of the rotating impeller in the classification chamber, the relationship between the carrying force of the airflow that carries particles and the centrifugal force caused by the swirling airflow of the rotating impeller depends on the position of the blades of the rotating impeller. But it will be almost the same.

Therefore, the critical particle diameter at the outer circumferential portion of the rotary impeller can be made almost the same, so that the particle size distribution width of the obtained pulverized product can be narrowed and a uniform product can be efficiently obtained.

(2) The fan action of the crushing means forms a circulating airflow from the classification chamber to the crushing chamber, and the rotating disk of the crushing means uses this circulating airflow and the primary airflow that conveys the raw material for crushing to the peripheral area of the crushing means. In order to separate the particles and prevent them from interfering with each other, the coarse particles conveyed to the crushing means by the circulating air current are repeatedly crushed without delay to improve the crushing efficiency.

(3) The airflow flowing into the classification chamber from the air pocket provided opposite the outer circumferential surface of the rotary impeller through the negative side gap causes the coarse particles in the classification chamber to move toward the transfer chamber and mix into the fine powder. to prevent Furthermore, the airflow flowing from the same air pocket into the classification chamber through the secondary gap prevents the fine powder that had been transported to the transport chamber from returning to the classification chamber and reducing the classification effect.

(4) By moving the supply device for the raw material for pulverization to the inclined wall portion of the classification chamber, the device can be easily changed to a vertical type.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of one embodiment of the present invention, Fig. 2 is a front view of the crushing means, Fig. 3 is a perspective view of essential parts showing an example of the assembly of the crushing means, and Fig. 4 is the same as Fig. 1. 5 is a perspective view of essential parts showing the assembly of another embodiment of the crushing means, and FIG. 6 is a longitudinal sectional view of another embodiment of the present invention. be. 1. IA... Feeding device 2... Grinding means 3...
Rotating impeller 8, 8A...first drive shaft 9...
Rotating disk 12...Connecting member 13.14...
・Annular disk 15... vane plate 26... vane
27...Intake passage 30.30A...Second drive shaft 39...Annular air pocket 40...-Next side gap 41
...Secondary side gap 50...Air supply port A...Supply chamber B...Crushing chamber C...Classification chamber
D...Transportation room Figure 4

Claims (3)

[Claims] (1) The raw material for pulverization supplied to the pulverization chamber along with suction air from the air supply port is pulverized by a rotary pulverizer, and the fine powder of a certain particle size or less in the pulverized material is air-transported to the next classification chamber. It is taken out of the equipment by an exhaust fan connected to the transfer chamber through the intake passage of a rotary impeller installed in the room, and
In a pulverizer that repeatedly crushes coarse particles other than the fine powder by returning them to the crushing means side using centrifugal force acting on them, the crushing means includes a rotating disk fixed to a first drive shaft and a peripheral edge of this rotating disk. a plurality of connecting members held perpendicular to the rotating disk, two annular disks fixed to both ends of the connecting members in parallel with the rotating disk, and a disk held by these annular disks and protruding outward. The inner surface of the classification chamber is formed by a sloped wall surface that is sandwiched near the transfer chamber, and a rotary impeller held by a second drive shaft is installed in the center of the chamber. is cylindrical with a closed end face on the crushing means side,
A large number of rectangular blades are provided on the outer peripheral surface in the axial direction, and the inclined wall surface of the classification chamber has an annular air pocket communicating with the outside on the inner peripheral surface adjacent to the outer peripheral surface of the rotary impeller at the boundary with the transfer chamber. A pulverizer, characterized in that the air pocket is connected to the classification chamber and the transfer chamber by a primary side gap and a secondary side gap formed in opposite directions between the rotary impeller and the rotating impeller. (2) The primary side gap that connects the air pool and the classification chamber has a larger gap size than the secondary side gap that connects the air pool and the transfer chamber, and is formed to have a shorter dimension in the length direction of the rotary impeller. A pulverizer according to claim 1. (3) The crushing means and the rotary impeller each have a vertical first
, a supply device for the raw material for pulverization was installed on the second drive shaft, and faced the outer peripheral surface of the rotary impeller on the inclined wall surface of the classification chamber, and a horizontal intake passage was provided below the pulverizing means. A pulverizer according to claim 1 or 2.