JPH0647079B2 - Pulverizer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine crusher, which mainly crushes solid substances such as ores, ceramics and foods to obtain fine powder having a narrow particle size distribution range (around 100 μm to several μm).
Used to make.

[0002]

2. Description of the Related Art As a conventional device of this kind, for example,
(1) Japanese Patent Publication No. 50-21695, (2) Jpn.
39081, and (3) JP-A-64-43352.
The one disclosed in Japanese Patent Publication is known.

In the devices disclosed in the above (1) and (2) publications, the powder pulverized by the pulverizing rotor is placed on the air stream and is guided along a frustoconical guide plate having a large upper end. It is carried toward the upper end of a classification impeller concentric with the grinding rotor. In the impeller for classification, only the fine powder in the pulverized powder passes through the impeller by the air flow from the exhaust fan and is moved to the outlet side of the device. However, the coarse powder in the powder that does not pass through the inside of the impeller descends along the inside of the guide plate, and when it moves under the lower end of the guide plate and moves outward, it is subjected to the grinding action again by the grinding rotor.

In these devices, the fine powder and the coarse powder in the powder are repeatedly circulated in the vertical direction along the frustoconical guide plate for the coarse powder which is greatly affected by the centrifugal force of the rotary impeller. The powder is pulverized by a pulverizing rotor, and the fine powder in the powder is placed against the centrifugal force generated by the rotation of the impeller and placed on the air flow of the exhaust fan, and the classification is performed by the suction action that guides it inside the impeller. The powder taken out of the apparatus by the classifying action has a desired particle size by changing the air volume of the exhaust fan and the centrifugal force generated by the rotation of the impeller.

Further, in the apparatus disclosed in the third publication, the powder crushed in the crushing chamber is obtained from the arc-shaped oblong hole provided in the peripheral portion of the partition plate which divides the crushing chamber and the classification chamber. An air flow for transportation is ejected, and this air flow is swung along the inner wall of the classification chamber, then inverted by a frustoconical reflecting member facing the arc-shaped long hole of the partition plate, and rotated in the classification chamber. The airflow swirled near the outer circumference of the impeller is returned to the crushing chamber through the circular opening in the center of the partition plate. In the return airflow of the crushing chamber, only the fine powder in the powder conveyed by the airflow is sucked into the classification impeller by the suction action of the exhaust fan, and the coarse powder in the powder that is not sucked into the impeller is It is subjected to the crushing action again in the crushing chamber through the opening in the center of the partition plate. The principle of the classification action in this system is the same as that disclosed in the above-mentioned first and second publications.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the above device, since the air flow carrying the powder flows into the impeller from the upper large diameter part of the impeller, the passing speed of the air flow in the lower small diameter part of the impeller is slow, and the carrying force of the air flow for the powder particles is small. On the other hand, the centrifugal force generated by the impeller is proportional to the radius of the impeller, so that it becomes smaller toward the lower side of the impeller. Therefore, the impeller has a smaller diameter toward the lower side, so that the relationship between the conveying force C by the air flow and the centrifugal force F by the impeller is the same at any position of the blade for the same powder particle size. It had been.

However, if the set flow rate of the passing air flow changes, not only the reduction rate of the passing speed along the blades also changes, but also
This reduction rate does not always match the reduction rate of the radius of the impeller. Therefore, even if the centrifugal force F / conveyance force C can be made almost the same for the entire length of the blade for a certain air volume, the total length of the blade is always constant for any air volume. It is practically impossible to desire the same centrifugal force F / conveyance force C. For this reason, not only the limit particle size corresponding to the sieve mesh is different at both ends of the impeller, but also the particle size distribution width of the pulverized powder obtained at the outlet of the apparatus is widened.

Further, in the first and second devices, the powder pulverized by the pulverization rotor is carried by the swirling air current rising in the annular portion formed by the inner wall of the classification chamber and the truncated cone-shaped guide plate. However, during that time, the coarse powder in the powder is subjected to a centrifugal force larger than that of the fine powder, and thus rises along the inner wall of the classification chamber.
Next, the airflow makes a U-turn while swirling in the space sandwiched between the upper end of the guide plate and the ceiling of the classification chamber, and is then swirled into the rotating impeller by the action of the following exhaust fan. At this time, the coarse powder is once pressed against the ceiling of the classification chamber during the U-turn of the airflow having a small radius of curvature, and then moved toward the inner wall side of the guide plate by the centrifugal force caused by the swirling airflow during the descending movement.

On the other hand, in the gap between the upper end of the impeller and the housing, an obstacle such as a hanging flange is provided in the housing instead of the missing blade, and this portion passes through the impeller. Because it will be a short cut for the air flow,
The velocity of the airflow is highest. Therefore, coarse particles that are moving toward the inner wall of the guide plate are taken into the impeller by the airflow of a relatively high wind speed, and the coarse particles that are larger than the target limit particle diameter are usually called "Kobi". However, the quality of the fine powder may be deteriorated by being mixed in the fine powder from this portion.

Further, in the device described in the third publication, the air flow reversed by the reflecting member is a fine powder having a particle size not larger than the limit particle size in the course of swirling and moving toward the crushing chamber near the outer circumference of the rotary impeller. However, when the airflow is reversed by the reflection member, the larger the particles in the airflow, the stronger the inertial force, and the more they collide with the reflection member,
Some of them bounce back and jump directly into the impeller, which has the drawback that coarse particles called "Tobi" mix in the desired fine powder.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is not to exceed the limit particle size of the raw material for pulverization to be supplied, and also to provide a particle size distribution. An object of the present invention is to provide a fine pulverizer having high pulverization efficiency, which can pulverize into a powder having a narrow width.

[0012]

In order to achieve the above object, according to the present invention, a pulverizing raw material supplied to a pulverizing chamber is pulverized by a rotary pulverizing means, and a pulverized pulverized product has a constant particle size. While taking out the following fine powder from the transfer chamber connected to the blower by the classifying means in the classifying chamber to the outside of the device,
In a fine pulverizer for returning coarse powder having a certain size or more to a pulverizing chamber and pulverizing it repeatedly, the pulverizing means includes a rotating disc fixed to the first drive shaft and two parallel discs on both sides of the disc. A large number of blade plates that are held by the annular disc and project outward in the radial direction, and are formed by toothed lining members that are provided on the inner peripheral surface of the crushing chamber that surrounds the outer peripheral side of the blade plates, and the classification means is A rotary impeller having a cylindrical outer shape of different diameter with one end closed by arranging a number of strip-shaped blades parallel to the axis on the outer peripheral surface, and the rotary impeller. And a circulator of powder, which is formed by a double-cylinder housing that surrounds the crushing unit, connects the annular opening formed on the side surface of the outer periphery of the crushing chamber to the inner cylinder of the double-cylinder of the classification chamber. Open the center of the grinding chamber with the annular space formed between the passage and the double cylinder of the classification chamber. It is formed by a coarse powder return passage connecting the parts characterized by comprising. In the above structure, there is provided a fine crusher in which the outlet side opening of the crushed material transport passage of the circulation means is eccentrically connected to the center of the rotary impeller on the front side of the inner cylinder in the classification chamber. Further, in the above configuration, the inner peripheral surface of the partition plate annularly provided between the classification chamber and the transfer chamber is formed into an edge shape, and one surface of the inner peripheral surface of the edge shape has a large diameter of the rotary impeller. Provided is a fine pulverizer in which a surface transitioning from a cylindrical portion to a small-diameter cylindrical portion is brought close to and a tip of an edge is brought close to an outer peripheral surface of a ring portion of the small-diameter cylindrical portion. Furthermore, in the above configuration, the inner peripheral surface of the annular partition plate provided between the classification chamber and the transfer chamber is brought close to the outer peripheral surface of the ring portion of the small-diameter cylindrical portion of the rotary impeller, and the inner peripheral surface of the partition plate is Between the surface and the outer peripheral surface of the ring portion, an annular air pool connected to the outside air or a pressurized air source, and a primary side gap and a secondary side gap for connecting the air pool to the classification chamber and the transfer chamber are provided. A fine crusher is provided.

[0013]

[Operation] When the apparatus is operated by supplying the raw material for grinding, the first
Crushing means having a vane plate rotated by a drive shaft,
The rotary impeller rotated by the second drive shaft and the exhaust fan connected to the transfer chamber form a transfer airflow from the air supply port to the transfer outlet in the internal space of the device. The pulverizing raw material supplied to the pulverizing chamber is conveyed to the peripheral portion of the rotating disk by the conveying air flow, and the raw material is crushed by the impingement action on the blade plate and the peripheral wall of the pulverizing chamber.

The pulverized powder is carried to the outer peripheral portion of the rotary impeller of the classification chamber by the air flow rising in the crushed material transport passage, but the suction air flow has a certain particle size which receives a suction force larger than the centrifugal force by the swirling air flow. The fine powder is taken into the rotary impeller and taken out of the apparatus from the transfer chamber. On the other hand, the coarse powder that receives a centrifugal force larger than the suction force by the swirling air flow is returned from the annular space formed between the double cylinders of the classification chamber to the central opening of the crushing chamber through the coarse powder return passage, It is repeatedly crushed until it becomes a fine powder with a certain particle size or less. By providing the rotary impeller with a cylindrical shape having a different diameter and surrounding the ring portion of the small-diameter cylindrical portion with the partition plate, it is possible to prevent the coarse powder in the classification chamber from short-circuiting and flowing into the transfer chamber.

[0015]

【Example】

[Embodiment 1] FIGS. 1 to 7 show an embodiment of the present invention. In FIG. 1, the inside of the main body case 2 is excluded by a supply chamber A equipped with a supply device 1, a crushing chamber B for storing crushing means, and a passage and a classification for carrying crushed materials from the crushing chamber B to a classification chamber D above the crushing chamber. It consists of a circulation case C consisting of a passage for returning the coarse powder from the classifying chamber D to the crushing chamber B, a classifying chamber D for housing the rotary impeller 3, and a transfer chamber E to which a fan is connected to the transfer outlet 4. In the central portions on the frame side of the supply chamber A and the transfer chamber E, bearing cases 5 and 6 projecting in the horizontal direction, respectively.
Are screwed to the overlapping portions of the flange portions 5a and 6a.

Reference numeral 8 is a horizontal first drive shaft supported by the bearings 7, 7 in the bearing case 5. One end of the first drive shaft 8 is projected to the crushing chamber B, and the other end thereof is the bearing case. 5 is projected outward. A boss portion 9a of a rotating disk 9 that constitutes a crushing means is integrally connected to the first drive shaft 8 in the crushing chamber B by a key 10, and the boss 9a of the rotating disk 9 has a boss 9a of the first drive shaft 8. The nut 11 that is screwed into the male thread formed on the small diameter portion is pressed against the inner ring of the bearing 7 through the spacer 16 to determine the axial position with respect to the first drive shaft 8, and at the same time, the rotation circle. The torque required to rotate the plate 9 can be transmitted. The other end of the first drive shaft 8 projecting outward from the bearing case 5 is connected to a drive motor (not shown) that rotates the crushing means via a speed reducing means.

The crushing means includes a rotating disc 9 attached to the first drive shaft 8 and a plurality of, for example, five connecting members 12 which intersect the peripheral edge of the rotating disc 9 at right angles and project in the radial direction. And two annular discs 13 and 14 which are fixed to the left and right ends of the coupling member 12 and which are parallel to the rotating disc 9, and the stepped pins sandwiched in the peripheral portions of these annular discs 13 and 14. A so-called turbo impeller, which is configured by a required number of vanes 15 that are swingably supported by 15a and protrudes outward, has a performance of exerting a powerful fan effect by rotation.

A toothed lining member 17 is provided so that a clearance δ ₁ maintains a set value (for example, about 1 mm) between the tip of each blade 15 provided on the circumference of the turbo impeller. Is inserted, and an annular cooling jacket 18 is formed between the outer peripheral portion of the toothed lining member 17 and the inner peripheral surface of the main body case 2. On the side surface of the crushing chamber B on the side of the supply chamber A, an annular side lining member 19 that faces the annular disc 13 and the vane plate 15 and contacts the toothed lining member 17 is attached.

Inside the supply chamber A above the drive shaft 8, there is provided a supply device 1 equipped with a feed screw in a direction perpendicular to the drive shaft 8. This supply device 1 is provided outside the fine pulverizer. Driven by a motor (not shown), the raw material for pulverization in the feed hopper (not shown) is supplied to the pulverization chamber B. The spacer 16 that abuts the bearing 7 and the front cover 2 that is fitted to the spacer 16 and closes the inner opening of the bearing case 5
An annular air reservoir 23 is formed on the inner peripheral surface of 2, and the air reservoir 23 communicates with the supply chambers A on both sides of the air reservoir 23 and the space inside the bearing case 5, and also the bearing case 5
An air passage 24 provided in the air passage communicates with a source of compressed air or the outside air. An outer cover 25 is attached to the opening of the bearing case 5.

Therefore, during operation, air flows from the air source 23 communicating with the pressurized air source or the outside air to the supply chamber A side in the negative pressure state where the pressure is lower than the outside air, and the powder in the supply chamber A becomes a spacer. Since the intrusion into the gap between the front cover 22 and the front cover 16 is prevented, various troubles caused by the intrusion of powder are prevented.

At the center of the classification chamber D located above the crushing chamber B, a hollow cylindrical rotary impeller 3 fixed to the second drive shaft 30 is provided. On the outer peripheral surface of the rotary impeller 3, a large number of stepped blades 26 arranged in parallel with the axial direction are provided at equal pitches along the circumference, and the outside of the blades is pinched to have a large diameter from the air inlet side. A cylindrical portion 3a and a small diameter cylindrical portion 3b are formed. An intake passage 27 penetrating the outer peripheral surface of the rotary impeller 3 is formed between the adjacent blades 26, 26 in the large-diameter cylindrical portion 3a.

Several stay plates 29 project from the boss portion 28 at the left end of the rotary impeller 3, and the right end of the stay plate 29 has inner and outer diameters equal to the step-falling portions 26a of the stepped blades 26, and the step-falling portions. Ring 2 connected to 26a
6b and the outer diameter are shared and are integrally connected to each other to form a small-diameter cylindrical portion 3b of the rotary impeller 3.

A partition plate 36, which is a fixed-side member, surrounds the portion of the rotary impeller 3 that transitions from the large-diameter cylindrical portion 3a to the small-diameter cylindrical portion 3b with a predetermined gap. That is, maintaining the gap [delta] ₄ for some length l ₄ of the end of the large-diameter cylindrical portion (left), a gap [delta] ₅ for slope 3c transition from the large-diameter cylindrical portion 3a to the small-diameter cylindrical portion 3b Keeping a gap δ ₆ from the starting point of the small-diameter cylindrical portion 3b, an edge-shaped inner surface having a slight parallel length l ₆ is formed with respect to the rectangular ring 26b.

Outside the small-diameter cylindrical portion 3b of the rotary impeller 3 formed by the stay plate 29, a spiral case 38a having a spiral origin close to the small-diameter cylindrical portion 3b is surrounded, and the case 38a and its right opening. A transfer chamber E is formed by the partition plate 3b that covers the portion.

On the other hand, the boss portion 28 of the rotary impeller 3 is integrally connected to the shaft neck of the second drive shaft 30 protruding horizontally from the bearing case 6 by the key 31, and also on the right side of the rotary impeller 3. The cover 32 that covers the opening is attached to the second drive shaft 30.
Rotating impeller 3 is fixed by a bolt 33 that is screwed to the end face of
The rotary impeller 3 is positioned by pressing against the inner ring of the bearing 34 through a positioning spacer 35 inserted between the boss portion 28 of the bearing and the bearing 34 in the bearing case 6, and at the same time required for the impeller 3. This enables the transmission of various rotation torques.

The large-diameter cylindrical portion 3a of the impeller 3 and the end cover 32 form a boundary between the outside (primary side) of the impeller 3 and the inside (secondary side) of the impeller 3.

A circulating case C is provided on the opposite side of the transfer chamber E and the crushing chamber B placed above and below, respectively, and a circulation case C for connecting the two is provided, and the opening of the upper flange 53b of the case C is a partition plate. 36 is pressed against the flange 38b of the spiral case to close the opening of the transfer chamber E, and the opening of the lower flange 52 of the case C presses the ear portions 51a and 51b of the flange of the return chute 51, thereby closing the return chute 51. It is fixed and connected to the opening of the crushing chamber B through the inside and outside of the chute 51.

The upper side of the circulation case C, which is in contact with the transfer chamber E, has a cylindrical shape 21, and forms a double cylinder concentric with the impeller 3 together with an inner cylinder 20 provided in the middle of the rotary impeller 3. The right side of the inner cylinder 20 is removably fitted into the case C, and the left side 20b of the inner cylinder 20 is an opening provided with a slight gap δ ₇ between the inner cylinder 20 and the partition plate 36. 3, the double cylinders 20 and 21 and the partition plate 36 form a classification chamber D.

The return chute 51 has a frusto-conical deep plate shape 51d having a specially shaped flange 51c, an unperforated ear 51a on the upper portion of the flange 51c, and an arcuate shape on the lower portion of the flange 51c. It has an ear 51b having an opening 51b ', the outer diameter of which is removably fitted into a circular recess provided in a flange portion 52 which is in contact with the crushing chamber B in the lower part of the circulation case C. The bottom surface of the arc-shaped opening 51b 'is made to coincide with the root diameter of the toothed lining 17 (Fig. 7).

Ears 51a and 51 on the flange 51c
The outer diameter of the portion excluding b and the upper surface of the arc-shaped opening are slightly smaller than the inner diameter of the toothed lining 17, and a small gap δ ₃ (for example, about 10 mm is provided between the inner diameter of the lower flange 52 of the circulation case C and the inner diameter of the lower flange 52). ) Is formed, and a slight gap δ ₂ (for example, about 1 mm) is provided between the side surface of the flange 51c facing the crushing chamber B and the rotating annular disk 14, and the center of the flange 51c is A circular opening 51f that communicates with the central opening of the annular disc 14 is provided.

The basin 51d is provided with a chimney-shaped protrusion 51e having a rectangular cross section, which is eccentric to the bottom surface of the basin 51d and opens upward.

On the opposite side of the classification chamber D in the upper part of the circulation case C, a right conical truncated cone 53a is formed with the right side opening (circle) of the inner cylinder 20 as the bottom face, and the lower part of the case C is the lower part. A frusto-conical body 52 that encloses the deep dish portion 51d of the return chute 51 with the central opening of the flange 52 as the bottom surface.
a is formed, and communication passages 54 and 55 having a rectangular cross section that vertically connect both conical bodies 53a and 52a are provided. In particular, the inner width of the communication passage 54 is brought into close contact with the outer width of the protruding portion 51e of the return chute 51, In addition, the left side of the intermediate wall 53b of the circulation case that provides a recess for fitting at the right end of the inner cylinder 20 contacts the back surface (right side) of the protruding portion 51e when the return chute 51 is mounted, so that the intermediate wall 53b is in contact. Determine the position of. As a result, in the classifying chamber D, the coarse powder removed in the space between the inner cylinder 20 and the outer cylinder 21 is removed from the inner passage 54 and the return chute 5.
A passage 54 is formed that passes through the inside of 1 and returns to the central suction side of the rotating disk 9 in the grinding chamber B without delay.

The deep pan 51 of the return chute 51
d, the space surrounded by the protruding portion 51e, the back surface of the intermediate wall 53b of the case C, the upper side of the case C, and the inner side of the lower cones 53a, 52a, the crushed product generated in the crushing chamber B is stored in the classification chamber B. To form a path 55 through which the upward conveying airflow carried to the inside of the inner cylinder 20 passes,
Further, the upper opening of the crushed material transport passage 55 is provided at a position eccentric with respect to the upper conical body 53a of the case C with respect to the extension line of the axis of the rotary impeller 3, and as a result, the upward airflow is preliminarily reserved. It is introduced inside the inner cylinder 20 while turning.

The right side opening of the bearing case 6 is provided with the spacer 3
It is closed by a front cover 45 that fits with the outer periphery of 5. The spacer 35 and the front cover 4 around the spacer 35
An annular air reservoir 47, which is communicated with a pressurized air source or the outside air by a ventilation passage 46, is provided at a portion where the air passage 47 and the outer periphery of the spacer 35 are arranged between the outer periphery of the spacer 35 and the inner periphery of the front cover 45. It is communicated with the transfer chamber E through a sealing gap 48 formed in. Therefore, during operation, air is blown into the negative pressure transfer chamber E through the air passage 46, the air reservoir 47, and the sealing gap 48, and air is sealed. It is taken out of the transfer chamber E by an air exhauster (not shown) connected to the.

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

[Embodiment 2] Embodiment 2 is shown in FIG. 8, and instead of the partition plate 36 in the first embodiment, a partition plate 37 having an annular primary air reservoir 42 by a cover 37b is a recess of a flange 38b of a spiral case. And is fixed by the opening of the upper flange 53b of the circulation case C. The inner peripheral surface of the partition plate 37, like the partition plate 36, maintains a gap δ ₄ with respect to the short length l ₄ at the end of the large-diameter cylindrical portion 3a of the rotary impeller 3 and keeps a small diameter from the large-diameter cylindrical portion 3a. Cylindrical part 3b
The gap δ ₅ is maintained also on the slope 3c that shifts to.

The rectangular ring 2 which is a part of the small diameter cylindrical portion 3b.
An annular groove-shaped secondary air reservoir 39 is formed on the inner peripheral surface of the partition plate 37 with respect to the outer peripheral surface of 6b. The inner peripheral surface of the partition plate 37 and the outer periphery of the square ring 26b are formed before and after the secondary air reservoir 39. A narrow gap δ ₈ is maintained between the surface and the surface, and the length of the gap portion is the length l _{7 of the} primary side gap close to the slope 3c of the blade of the rotary impeller 3.
Is shorter than the length l ₈ of the secondary side gap on the opposite side. The classifying chamber D is communicated with the transfer chamber E by these gaps δ ₄ , δ ₅ , δ ₈ and the secondary air reservoir 39.

The primary air reservoir 42 has a large number of communication passages 4 which are equally divided in the circumferential direction in the inner flange portion of the partition plate 37.
The air which is connected to the secondary air reservoir 39 by 3 and flows in through the air intake 44 provided in the flange 38b of the spiral case 38a and the hole 44a provided in the cover 37b oppositely to the secondary air reservoir 39 is evenly distributed. Play a role in allocating to. Therefore, in the classification chamber D and the transfer chamber E, which have a negative pressure during operation, the air in the secondary air reservoir 39 communicated with the pressurized air source or the outside air continuously passes through the primary side gap 40 and the secondary side gap 41. The powder is prevented from entering the gap between the rotary impeller 3 and the partition plate 37 in the air flow before classification, and the powder moves through the gaps 40 and 41 to the transfer chamber E side. Prevent.

The other structure is the same as that of the first embodiment. Next, the operation of the device will be described.

When each motor of the fine pulverizer is driven to bring the apparatus into an operating state, the raw material for pulverization supplied to the supply chamber A by the feed screw of the supply apparatus 1 is supplied to the supply chamber by the suction airflow formed in the apparatus. It is conveyed to the inner peripheral wall side of the crushing chamber B along the rotating disk 9 through the central opening of the annular disk 13 on the A side, and is crushed by a number of orbiting blades 15 and toothed lining members 17. .

The crushed material crushed by the crushing means is carried out by the air flow that swirls inside the toothed lining 17, and the outer circumference of the flange 51c of the return chute 51 and the opening of the ear 51b and the lower annular flange of the circulation case C are taken. By passing through the peripheral clearance δ ₄ formed by the inner diameter of 52 and the crushed material transport passage 55 of the circulation case C, the passage 55 is eccentrically connected to the truncated cone cylindrical body 53a, , Classifying chamber D while forming a preliminary swirling airflow
It is carried into the inner cylinder 20 of the.

The pulverized material carried into the classifying chamber D is subjected to both suction force by the suction airflow into the rotary impeller 3 and centrifugal force due to the swirling airflow around the rotary impeller 3. In the vicinity of the impeller 3, the suction force is larger than the centrifugal force for the fine powder in the pulverized material, and the centrifugal force is larger than the suction force for the coarse powder in the pulverized material. For this reason, among the pulverized products moving in the radial direction of the rotary impeller 3, only the fine powder moves on the suction airflow and moves from the intake passage 27 between the blades 26 into the rotary impeller 3. In addition, since a preliminary swirling speed is imparted to the airflow before entering the inner cylinder 20, a centrifugal force sufficient for selecting coarse powder and fine powder is already present at the inlet (b) of the inner cylinder 20. Since it acts on the powder, the correct sorting operation is performed from the beginning. That is, while the air flow carrying the pulverized product swirls in the inner cylinder 20 toward the partition plate 36 or 37, the moving directions of the coarse powder and the fine powder to the outer side and the inner side in the radial direction do not change from beginning to end, Moreover, the limit particle diameter can be kept constant on the outer circumference of the rotary impeller 3.

Thus, the air flow carrying fine powder into the rotary impeller 3 passes between the stay plates 29 supporting the rotary impeller 3, and is carried from the transport outlet 4 to a fine powder take-out device (not shown).

A) On the other hand, the remaining air flow, from which most of the fine powder has been removed, makes a U-turn outward at the edge of the inner cylinder 20 on the opening side, and then forms an annular space between the inner cylinder 20 and the outer cylinder 21. Through the coarse powder return passage 54 of the circulation case C, through the central opening 51f of the return chute 51, and by the fan effect of the turbo-type impeller, through the central opening of the annular disc 14 to the peripheral portion of the blade plate 15. It is carried and repeatedly subjected to the crushing action until it becomes a size equal to or smaller than the particle size that is sucked into the rotary impeller 3.

B) Further, the rotating disk 9 of the pulverizing means conveys the circulating air flow between the pulverizing chamber B and the classifying chamber D and the pulverizing raw material supplied from the supply device 1 to the peripheral portion of the pulverizing means. Divide the primary airflow so that they do not interfere with each other.

C) Further, the annular disc 14 and the flange 51c of the return chute 51 maintain a narrow gap δ ₂ in a wide area, so that the air flow discharged from the outer periphery of the crushing chamber B directly passes through the annular disc 14. Since there is no short circuit toward the central opening, the crushed material produced in the crushing chamber B is reliably transported to the classifying chamber D.

As a result of these (a, b, c), both the new crushing raw material and the recycled coarse powder are efficiently crushed.

In the classification chamber D, the air flow swirls into the inner cylinder 20, passes through the periphery of the rotary impeller 3, and reaches the throat portion around the inner boss portion 28.
At this time, the total length of the air flow path is almost the same when entering from the non-driving side and when entering from the transfer chamber E side, and therefore there is no great difference in the fluid resistance received by the air flow. The invasion speed of the air flow containing the fine powder passing through the wheel 3 becomes equal in the length direction of the intake passage 27 of the rotary impeller 3. Moreover, the axial resistance of the air flow passing through the small-diameter cylindrical portion 3b of the rotary impeller 3 is uniform on the circumference due to the action of several stay plates 29 rotating in the spiral transfer chamber E. Therefore, the velocity of the air flow passing through the intake passage 27 has a uniform distribution on the circumference.

On the other hand, it has been known from the results of the research so far that the force of the carrier airflow to draw the particles into the rotary impeller 3 is proportional to the product of the outer peripheral length of the particles and the airflow velocity. The force of drawing the particles in the inside of the rotary impeller 3 is the same in the length direction of the intake passage 27.

The centrifugal force, which opposes this pulling force, is proportional to the product of the mass of the particle and the square of the swirling speed, and is inversely proportional to the distance from the center of rotation. Therefore, since the particles are considered to have the same swirling speed, the limit particle diameter determined by the balance between the force of drawing the particles into the rotary impeller and the centrifugal force is the same throughout the rotary impeller (inflow side).

Therefore, according to the apparatus of this embodiment, the width of the particle size distribution of the particles taken out from the conveying outlet 4 is made narrower than that in the conventional case in which the limit particle diameter changes in the length direction of the blade, and is uniform. Fine powder can be obtained.

The airflow that swirls into the inner cylinder 20 of the classification chamber D carries coarse powder, especially large coarse particles called "tobi", from the beginning along the inner wall of the inner cylinder 20. Even when the coarse powder or large coarse particles collide with the partition plate 36 or 37 due to inertia, the U-turn is made outward at the opening-side edge of the inner cylinder 20 without approaching the rotary impeller 3, and after repulsion. Since it always moves radially outward in the classification chamber D,
Coarse powder or large coarse particles hardly fall into the inside of the rotary impeller 3.

The outer peripheral surface of the rotary impeller 3 and the partition plate 36 or 3
Since the gaps δ ₄ and δ ₅ with the inner peripheral surface of 7 are sufficiently small, the gas in the space (gap) close to the inner peripheral surface of the partition plate is drawn to the air flow passing between the blades 26. Therefore, the behavior is almost the same as that of the other intake passage 27. During operation, the inside of and around the transfer chamber E and the rotary impeller 3 are in a negative pressure state due to the action of the exhaust fan, but due to the discharge effect of the stay plate 29, the edge of the inner peripheral surface of the partition plate 36 in the first embodiment. Although the portion near the transfer chamber E of FIG.
It is almost the same as the static pressure in the vicinity of. Therefore, in the gap δ ₆ between the tip of the edge and the rotary impeller 3, there is almost no air flow from the classification chamber D to the transfer chamber E. Therefore, due to the shape effect of the particles to be selected (flat ones are more susceptible to the force of the wind than spherical ones), even if coarse particles having a size equal to or larger than the limit particle size approach the partition plate 36, It is not conveyed to the transfer chamber E in a short circuit through the gap δ ₆ .

Therefore, the correct classification action is performed over the entire inflow side of the rotary impeller 3. Further, since the length of the gap δ ₆ is short (about 1 to 2 mm) and the size of the gap is not so narrow (about 1 mm), it is possible to deal with adhesive substances without any problem.

In the second embodiment, a secondary air reservoir 39 for air-sealing is provided in both the classification chamber D and the transfer chamber E,
The amount of air flowing out through the primary gap 40 having a short gap is larger than the amount of air flowing out from the secondary gap 41 having a long gap. The air seal of the primary side gap 40 has a particularly small limit particle size in order to actively prevent coarse particles (tobi) larger than the limit particle size in the classification chamber D from moving to the transfer chamber E side. It is also effective in cases.

The secondary side gap 41 prevents the fine powder carried into the carrying chamber E from returning to the classifying chamber D and prevents the classification efficiency from decreasing.

For example, when the permissible value of jumps exceeding a certain limit particle diameter is 0.1%, Example 1 is adopted and 0.01% is used.
If only that is allowed, the second embodiment is adopted.

In both the first and second embodiments, which are in a negative pressure state during operation, the supply chamber A, the transfer chamber E, and the bearing case 5 are supplied from the air reservoirs 23 and 47 communicating with the pressurized air source or the outside air. Since air is blown into the bearings 6 and 6 to perform an air-sealing action, it is possible to prevent the powder contained in the airflow from entering the bearings 7 and 34 and causing trouble.

Further, since the crushing means and the rotary impeller 3 are driven separately, the desired particle size can be obtained by independently adjusting the rotational speed of both and the amount of suctioned air from the exhaust fan to the optimum operating state. It is possible to efficiently produce products with a particle size distribution width.

[0060]

Since the present invention is configured as described above, it has the following effects. In the fine pulverizer according to claim 1,

(1) The resistance received when the air flow carrying fine powder enters the rotary impeller of the classification chamber is almost the same regardless of the position on the circumferential surface of the rotary impeller. Therefore, the speed at which the airflow passes through the intake passage of the rotary impeller is uniform with respect to the entire outer peripheral surface on the intake side of the rotary impeller. As a result, in the vicinity of the rotary impeller, the relationship between the conveying force of the air flow that conveys the particles and the centrifugal force due to the swirling airflow of the rotary impeller becomes substantially the same at any position in the axial direction of the blade of the rotary impeller. .

Therefore, since the limit particle diameters in the outer peripheral portion of the rotary impeller are almost the same, a uniform product having a narrow particle size distribution width can be efficiently produced.

(2) Further, since the coarse powder and coarse particles contained in the carrier airflow are subjected to a centrifugal force larger than the suction force of the suction airflow due to the swirling airflow in the classification chamber, they almost come close to the outer peripheral surface of the rotary impeller. Also, due to the action of the double cylinder, coarse powder and coarse particles are efficiently removed from the classification chamber, and further, a circulating air flow that contains coarse powder or coarse particles and is returned from the classification chamber to the grinding chamber, The primary air flow that supplies the crushing raw material to the crushing chamber is not only divided by the rotating disk of the crushing means so as not to interfere with each other, but also at the boundary between the crushing chamber and the circulation case, the circular disk and the return. Due to the polymerization between the flanges of the chute, the air flow that carries out the crushed material and the return air flow from the classification chamber are sufficiently isolated, so that the coarse powder or coarse particles conveyed to the crushing means by the circulating air flow are repeatedly efficiency It can be crushed well and transported to the classification chamber.

In the fine pulverizer of claim 2, the passage of the air flow for transporting the pulverized material from the pulverizing chamber to the classifying chamber is deflected and communicated with the cylindrical body forming the extension of the inner cylinder of the classifying chamber. As a result, the air flow carrying the pulverized material is given a preliminary swirling motion before entering the inner cylinder.Therefore, around the rotary impeller for classification, the sorting action by the centrifugal force of the powder causes the rotary impeller to move. The coarse particles work normally from the inlet side in the axial direction, and the coarse particles continue to gather and move from the outlet side of the crushed material transport passage toward the wall of the inner cylinder. Absent.

In the fine pulverizer of claim 3, the static pressure difference between the front and rear of the partition plate which forms the boundary between the classification chamber and the transfer chamber around the rotary impeller is reduced, and the partition plate and the rotary impeller are substantially provided. By eliminating the short-circuit air flow from the classification chamber to the transfer chamber through the gap with the outer circumference, coarse powder in the primary air flow is prevented from spilling into the transfer chamber, and the gap is made relatively large. It is also possible to process adhesive powder.

In the fine pulverizer of claim 4, the coarse powder in the classifying chamber is positively moved to the carrier chamber through the gap by the air flow blown from the air reservoir into the classifying chamber and the carrier chamber. Therefore, it is possible to strictly prevent the fine powder taken out of the apparatus from the transfer chamber from containing coarse powder or coarse particles having a particle size larger than the limit particle size.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view of a part surrounded by a dashed-dotted circle in FIG.

FIG. 3 is a right side view of FIG.

FIG. 4 is a vertical sectional view of only the crushing means.

FIG. 5 is a front view of the left half showing a state in which a coupling member is attached to a rotating disc of the crushing means.

FIG. 6 is a front view showing the left half of the annular disc of the crushing means.

FIG. 7 is a return chute with the circulation case removed.

FIG. 8 is an enlarged cross-sectional view showing a portion corresponding to FIG. 2 in the case of the second embodiment.

[Explanation of symbols]

 3 Rotary Impeller 8 1st Drive Shaft 9 Rotating Disc 13, 14 Annular Disc 15 Blade Plate 17 Toothed Lining Part 20 Inner Cylinder (Double Cylinder) 21 Outer Cylinder (Double Cylinder) 26 Rotating Impeller Blade 30 Second drive shaft 36 Partition plate [1] 37 Partition plate [2] 39 Secondary air reservoir 40 Primary side gap 41 Secondary side gap 54 Coarse powder return passage 55 Grinded material transport passage A Supply chamber B Grinding chamber C Circulation case D Classification room E Transport room

Claims (4)

[Claims] 1. A crushing raw material supplied to a crushing chamber is crushed by a rotary crushing means, and fine powder having a particle size not more than a certain size in the crushed crushed material is conveyed by a classifying means connected to an exhaust fan by a classifying means. In the fine pulverizer which takes out from the chamber to the outside of the device and returns coarse powder having a certain size or more to the pulverizing chamber to repeatedly pulverize, the pulverizing means includes a rotating disc fixed to the first drive shaft,
A large number of vanes, which are held on two annular discs parallel to the disc on both sides of the disc and project outward in the radial direction, and are provided on the inner peripheral surface of the crushing chamber surrounding the outer peripheral side of the vane plate. Formed by a toothed lining member, the classifying means has a large number of strip-shaped blades parallel to the axis lined up on the outer peripheral surface so that one end is closed and a large-diameter cylindrical portion and a small-diameter cylindrical portion are provided. A rotary impeller having a cylindrical outer shape, having a ring portion at a starting point of a small diameter cylindrical portion, and being held by a second drive shaft;
It is formed by a partition plate annularly provided between the classification chamber and the transfer chamber and surrounding the ring part of the rotary impeller, and a double-cylindrical housing surrounding the rotary impeller. The circulation means is a ring formed between the crushed material transport passage that connects the annular opening formed on the side surface of the outer periphery of the crushing chamber to the inner cylinder of the double cylinder of the classification chamber and the double cylinder of the classification chamber. A fine crusher characterized by being formed by a coarse powder returning passage connecting a space portion to a central opening of a crushing chamber. 2. The fine pulverizer according to claim 1, wherein the outlet side opening of the pulverized material transport passage of the circulation means is eccentrically connected to the center of the rotary impeller on the front side of the inner cylinder in the classification chamber. 3. An inner peripheral surface of a partition plate annularly provided between the classification chamber and the transfer chamber is formed into an edge shape, and one surface of the edge-shaped inner peripheral surface is a large diameter cylinder of a rotary impeller. The fine crusher according to claim 1, wherein the fine crusher is brought closer to a surface that transitions from the portion to the small-diameter cylindrical portion, and further the tip of the edge is brought closer to the outer peripheral surface of the ring portion of the small-diameter cylindrical portion. 4. The inner peripheral surface of an annular partition plate provided between the classification chamber and the transfer chamber is brought close to the outer peripheral surface of the ring portion of the small-diameter cylindrical portion of the rotary impeller so as to form an inner peripheral surface of the partition plate. An annular air reservoir connected to the outside air or a pressurized air source is provided between the outer peripheral surface of the ring portion, and a primary-side gap and a secondary-side gap that connect the air reservoir to the classification chamber and the transfer chamber. The fine crusher according to claim 1, wherein