Media-agitation type pulverizer

Abstract

[Problem] To resolve segregation of grinding media to thereby enable a large-flow-rate circulation operation while reducing wear of an agitating member and a grinding media separating member. [Solution] In a media-agitation type pulverizer, the agitating means comprises: a circular plate-shaped hub member (26) fixed to an end of a rotary drive shaft located inside a grinding chamber, wherein the rotary drive shaft extends front the side of one end of the grinding chamber into the grinding chamber; an annular end plate (28) disposed in spaced-apart relation to the hub member in an axial direction of the rotary drive shaft; a plurality of agitating members (30) fixed between the hub member and the end plate at circumferential intervals, in a posture where each of them protrudes radially outwardly from respective outer peripheries of the hub member and the end plate; and a plurality of grinding media scraping-out members (31) each extending radially inwardly with respect to the outer peripheries of the hub member and the end plate, wherein an open region as a part of an outer periphery of the agitating means other than thicknesses of the agitating members and the grinding media scraping-out members is formed as a grinding media circulation opening (22a) for circulating the grinding media from an inside to an outside of the agitating means, and wherein an area ratio of the grinding media circulation opening to a circumferential plane between opposing surfaces of the hub member and the end plate of the agitating means is set to 50 to 90%.

Claims

1. A media-agitation pulverizer comprising: a cylindrical grinding chamber; a cylindrical agitating means disposed inside the grinding chamber rotatably in coaxial relation thereto; a grinding media separating means disposed inside the agitating means in coaxial relation thereto; a grinding space disposed between an outer periphery of the agitating means and an inner periphery of the grinding chamber; grinding media contained in the grinding space; a material supply passage for supplying a slurry material into the grinding chamber; and a material discharge passage for discharging a dispersed and/or pulverized material to an outside of the grinding chamber, wherein the agitating means comprises: a circular plate-shaped hub member fixed to an end of a rotary drive shaft located inside the grinding chamber, the rotary drive shaft extending from the side of one end of the grinding chamber into the inside of the grinding chamber; an annular end plate disposed in spaced-apart relation to the hub member in an axial direction of the rotary drive shaft; a plurality of agitating members fixed between the hub member and the end plate at circumferential intervals, in a posture where each of them protrudes radially outwardly with respect to respective outer peripheries of the hub member and the end plate; and a plurality of grinding media scraping-out members for scraping out the grinding media residing inside the agitating means toward an outside of the agitating means, the grinding media scraping-out members being fixed between the hub member and the end plate at circumferential intervals, in a posture where each of them extends radially inwardly with respect to the outer peripheries of the hub member and the end plate, and wherein an open region as a part of an outer periphery of the agitating means other than thicknesses of the agitating members and the grinding media scraping-out members is formed as a grinding media circulation opening for circulating the grinding media from the inside to the outside of the agitating means, and wherein an open ratio as an area ratio of the grinding media circulation opening to a circumferential plane between opposing surfaces of the hub member and the end plate of the agitating means is 50 to 90%, and wherein the grinding media separating means comprises a separating means body and a support member supporting the separating means body, and wherein the separating means body has an outer diameter which is 80% or more of a diameter of a circle connecting respective inner edges of the grinding media scraping-out members, and a gap between the diameter of the circle connecting the inner edges of the grinding media scraping-out members and the outer diameter of the separating means body is three times or more greater than a diameter of each of the grinding media, and wherein the separating means body is completely received in an internal space of the agitating means.

2. The media-agitation pulverizer as recited in claim 1, wherein the open ratio of the grinding media circulation opening to the circumferential plane between opposing surfaces of the hub member and the end plate of the agitating means is 70 to 90%.

3. The media-agitation pulverizer as recited in claim 1, wherein a ratio of a radial length of an operating surface of each of the grinding media scraping-out members to a radial length of an operating surface of the agitating means is 3:7 to 7:3.

4. The media-agitation pulverizer as recited in claim 3, wherein the ratio of the radial length of the operating surface of each of the grinding media scraping-out members to the radial length of the operating surface of the agitating means is 4:6 to 6:4.

5. The media-agitation pulverizer as recited in claim 1, wherein an angle defined between an operating surface of each of the grinding media scraping-out members and a radial axis of the agitating means is 0 to 45 degrees.

6. The media-agitation pulverizer as recited in claim 5, wherein an angle defined between an operating surface of each of the grinding media scraping-out members and a radial axis of the agitating means is 10 to 40 degrees.

7. The media-agitation pulverizer as recited in claim 1, wherein each of a plurality of sets of the agitating member and the grinding media scraping-out member are integrated into a single piece.

8. The media-agitation pulverizer as recited in claim 1, wherein the grinding media separating means is fixed to the side of the other end of the grinding chamber, and wherein the separating means body is inserted into an internal space of the agitating means from the side of the other end.

9. The media-agitation pulverizer as recited in claim 8, wherein the separating means body has an overall length which is 20 to 80% of an overall length of the internal space of the agitating means.

10. The media-agitation pulverizer as recited in claim wherein the grinding media separating means is a screen type pulverizing media separating means.

11. The media-agitation pulverizer as recited in claim 1, wherein the support member has an outer diameter which is 50% or more of an inner diameter of the agitating means, and a gap between the inner diameter of the agitating means and the outer diameter of the support member is three times or more greater than the diameter of each of the grinding media, with respect to an inner diameter of the end plate of the agitating means.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a longitudinal sectional view of a media-agitation type pulverizer according to one embodiment of the present invention.

(2) FIG. 2 is a perspective view illustrating a major part of the media-agitation type pulverizer illustrated in FIG. 1.

(3) FIG. 3 is a perspective view illustrating only an agitating means in the major part illustrated in FIG. 2.

(4) FIG. 4 is a transverse sectional view of the media-agitation type pulverizer illustrated in FIG. 1, wherein the cross-section is taken to appropriately show a configuration of a member or component, and a barrel is omitted.

(5) FIG. 5 is a view corresponding to FIG. 4, which illustrates one modification of a structure of an agitating member and a grinding media scraping-out member.

(6) FIG. 6 is a graph presenting a result of a performance test for a media-agitation type pulverizer according to one embodiment of the present invention and a media-agitation type pulverizer as a comparative example.

DESCRIPTION OF EMBODIMENTS

(7) With reference to the accompanying drawings, a media-agitation type pulverizer of the present invention will now be described. FIG. 1 illustrates a media-agitation type pulverizer 10 according to one embodiment of the present invention. The media-agitation type pulverizer 10 has a grinding chamber 20 which comprises: a cylindrical barrel 12; an end plate 14 fixed to one end of the barrel 12; and a frame (not illustrated) fixed to the other end of the barrel 12 through a material-supply-passage flange 16. The grinding chamber 20 is constructed to form a hermetically-sealed grinding space C1 thereinside. As is well known, in the media-agitation type pulverizer, grinding media in the form of beads (not illustrated) are contained in the grinding space C1.

(8) The barrel 12 has an internal space in which an agitating means 22 is rotatably disposed. The agitating means 22 is disposed in coaxial relation to the barrel 12 and thus the grinding chamber 20. The agitating means 22 comprises: a circular plate-shaped hub member 26 fixed to one end of a rotary drive shaft 24 located inside the grinding chamber 20, wherein the rotary drive shaft 24 extends from the side of one end of the grinding chamber 20 into the grinding chamber; an annular end plate 28 disposed in spaced-apart relation to the hub member 26 in an axial direction of the rotary drive shaft 24; a plurality of agitating members 30 fixed between the hub member 26 and the end plate 28 at circumferential intervals, in a posture where each of them protrudes radially outwardly with respect to respective outer peripheries of the hub member 26 and the end plate 28; and a plurality of grinding media scraping-out members 31 for scraping out the grinding media residing inside the agitating means 22 toward an outside of the agitating means 22, wherein the grinding media scraping-out members 31 are fixed between the hub member 26 and the end plate 28 at circumferential intervals, in a posture where each of them extends radially inwardly with respect to the outer peripheries of the hub member and the end plate.

(9) An open region as a part of an outer periphery of the agitating means 22 other than thicknesses of the agitating members 30 and the grinding media scraping-out members 31 is formed as a grinding media circulation opening 22a for circulating the grinding media from the inside to the outside of the agitating means, wherein an open ratio as an area ratio of the grinding media circulation opening 22a to a circumferential plane between opposing surfaces of the hub member 26 and the end plate 28 of the agitating means 22 is set to 50 to 90%, particularly preferably 70 to 90%. This embodiment discloses an example in which each of a plurality of sets of the agitating member 30 and the grinding media scraping-out member 31 are formed in an integral structure. Alternatively, they may be separate members, as illustrated in FIG. 5. However, the agitating means having the integral structure makes it possible to set the open ratio to a larger value. If the open ratio goes beyond the above range, the thicknesses of the agitating members 30 and the grinding media scraping-out members 31 relatively decrease. This is likely to cause deterioration in strength and thus structural brittleness.

(10) The rotary drive shaft 24 extends to penetrate through the frame in the axial direction and then allow the other end thereof to be connected to a drive source via a non-illustrated well-known drive mechanism, so that it can be rotationally driven in a given direction. The rotary drive shaft 24 is provided with a non-illustrated shaft sealing element (mechanical seal or the like). The material-supply-passage flange 16 is formed with a material supply passage 16a for supplying a slurry material into the grinding space C1. The material supply passage 16a has a material supply port 16b for actually introducing the material into the grinding space C1 therethrough, wherein the material supply port 16b is preferably positioned on the side of a back surface of the agitating means 22, i.e., a back surface of the hub member 26. As is well known, in the media-agitation type pulverizer, grinding media in the form of beads (not illustrated) are contained in the grinding space C1.

(11) The agitating means 22 has an internal space in which a grinding media separating means 32 is provided such that it is disposed in coaxial relation to the rotary drive shaft 24 for the agitating means 22 to separate the grinding media dispersed in the slurry material, from the material. The internal space of the agitating means 22, particularly, a space between the grinding media separating means 32 and a cylindrical wall 22a of the agitating means 22, will hereinafter be referred to as a media separating space C2. As the grinding media separating means 32, it is possible to use a screen type (see FIG. 1) or a centrifugal blade type (not illustrated). In particular, a screen type grinding media separating means is effectively usable in the present invention.

(12) The screen type grinding media separating means 32 comprises: a separating means body 34 disposed inside the agitating means 22, and provided with a screen separator 34a therearound; and a support member 36 supporting the separating means body. The grinding media separating means 32 is fixed to the side of the other end of the grinding chamber, i.e., to the end plate 14, and the separating means body 34 is inserted into the internal space of the agitating means from the side of the other end. That is, the support member 36 has a base end fixed to the end plate 14, and extends from the base end into the internal space of the agitating means 22 to have a distal end to which the separating means body 34 is fixed.

(13) Preferably, the separating means body 34 is completely received in the internal space of the agitating means 22. More preferably, this separating means body has the overall length which is 20 to 80% of the overall length of the internal space of the agitating means 22. Preferably, the separating means body 34 is disposed in the internal space of the agitating means 22 at a position close to the hub member 26.

(14) Preferably, the separating means body 34 has an outer diameter which is 80% or more of a diameter of a circle connecting respective inner edges of the grinding media scraping-out members 31, and a gap between the diameter of the circle connecting the inner edges of the grinding media scraping-out members and the outer diameter of the separating means body is three times or more greater than a diameter of each of the grinding media. This is intended to make an action of the grinding media scraping-out members 31 more effective.

(15) Preferably, the support member 36 has an outer diameter which is 50% or more of an inner diameter of the annular end plate 28 of the agitating means 22, and a gap between the inner diameter of the agitating means and the outer diameter of the support member is three times or more greater than the diameter of each of the grinding media. In this case, the outer diameter of the support member 36 is equal to an outer diameter of the separating means body 34 at a maximum, and is preferably less than the outer diameter of the separating means body 34. This is intended to allow a mixture of the material slurry and the grinding media to easily flow into the separating space C2.

(16) A ratio of a radial length of an operating surface of each of the grinding media scraping-out members 31 to a radial length of an operating surface of a corresponding one of the agitating members 30 is 3:7 to 7:3, preferably, 4:6 to 6:4, particularly in the case where the two members are integrated into a single piece. Although the operating surface of the grinding media scraping-out member 31 may extend from an outer peripheral edge of the annular end plate 28 of the agitating means 22 and then protrude inwardly from an inner peripheral edge of the annular end plate 28, as illustrated in the drawing, it is preferable to terminate at the inner peripheral edge.

(17) In this embodiment, an angle defined between the operating surface of each of the grinding media scraping-out members and a radial axis of the agitating means 22 is 0 to 45 degrees, preferably, 10 to 40 degrees. Preferably, an scraping-out end of each of the grinding media scraping-out members 31 is configured as an acute-angled surface coming away from a surface of the separating means body 34 toward a rotation-directional downstream side thereof, as illustrated in FIG. 4.

(18) The grinding media separating means 32 is provided with a material discharge passage 38 extending from an outside of die grinding chamber 12 to an inside of the separating means body 34, as illustrated in FIG. 1. An end of the material discharge passage 38 opened to the inside of the separating means body 34 is formed as a material discharge port 40.

(19) Upon start of operation, the agitating means 22 is rotationally driven while slurry containing target particles to be pulverized is introduced as a material from the material supply passage 16a. The slurry introduced into the grinding space C1 is agitated to undergo rotational motion within the grinding space C1, together with the grinding media. According to the rotational motion of the grinding media the particles in the material slurry are pulverized or dispersed. Together with the grinding media, the material slurry enters mainly from an opening of an end of the agitating means 22 into the hollow internal space, i.e., the separating space C2, of the agitating means. Then, according to the grinding media separating means 32, the grinding media are separated from the material slurry, and only the material slurry is discharged outside the grinding chamber via the material discharge passage 38.

(20) During the above operation, the grinding media which primarily tend to adhere onto the screen separator 34a of the separating means body 34 of the grinding media separating means 32 are scraped out by the grinding media scraping-out members 31 of the agitating means 22 being rotated, and led from the inside to the outside of the agitating means 22 via the grinding media circulation opening 22a, whereafter the grinding media is re-used to pulverize or disperse target particles in material slurry.

(21) An instantaneous electric power was measured using the media-agitation type pulverizer 10 illustrated in FIGS. 1 to 4, under the condition that: glycerin (viscosity: 800 mP.Math.S (25 C.), 200 mP.Math.S (45 C.)) was used as slurry; a filling rate of the grinding media in the grinding space was fixed to 80%; and the open ratio of the grinding media circulation opening 22a was sequentially set to 30%, 45%, 55%, 65%, 75%, 85% and 95%, while a supply flow rate of the slurry was continuously changed. A result of the measurement was as presented in the graph of FIG. 5. When the open ratio was set to 95%, due to decrease in thickness of the agitating members and the grinding media scraping-out member, strength thereof deteriorates, so that the members were broken during the measurement. Thus, it was evaluated as unusable. As is evident from this graph, the present invention has advantageous effects.

LIST OF REFERENCE SIGNS

(22) 10: media-agitation type pulverizer 12: barrel 14: end plate 16: material-supply-passage flange 16a: material supply passage 16b: material discharge passage 18: frame 20: grinding chamber 22: agitating means 22a: grinding media circulation opening 24: rotary drive shaft 25: shaft scaling element 26: circular plate-shaped hub member 28: annular end plate 30: agitating member 31: grinding media scraping-out member 32: grinding media separating means 34: separating means body 34a: screen separator 36: support member