Abstract
A stirred ball mill including a grinding container, in which an agitator shaft having grinding elements is arranged, whereby a grinding chamber is formed between the grinding container and the agitator shaft, into which chamber the grinding elements extend and into which at least one inlet duct for grinding material opens and in which a dynamic separation device for grinding bodies is provided, the separation device having recesses for feeding back the grinding bodies, and in which the agitator shaft has at least one recess, which widens the separation device and extends in the axial direction into the grinding chamber for improved distribution of the grinding bodies in the grinding chamber.
Claims
1. An assembly for an agitator ball mill, comprising: an agitator shaft including: a first grinding disc including a first opening proximate a center of the first grinding disc, the first opening extending through the first grinding disc in an axial direction of the first grinding disc; and a second grinding disc including a second opening proximate a center of the second grinding disc, the second opening extending through the second grinding disc in an axial direction of the second grinding disc; and a distance bushing disposed between the first grinding disc and the second grinding disc of the agitator shaft, the distance bushing including an edge that sweeps over at least a portion of the first opening of the first grinding disc during rotation of the first grinding disc about an axis of the agitator shaft.
2. The assembly of claim 1, wherein the edge of the distance bushing sweeps over an entirety of the first opening during rotation of the agitator shaft.
3. The assembly of claim 1, wherein the edge of the distance bushing sweeps over at least a portion of the second opening of the second grinding disc during rotation of the agitator shaft.
4. The assembly of claim 3, wherein the edge of the distance bushing sweeps over an entirety of the second opening during rotation of the agitator shaft.
5. The assembly of claim 1, wherein the first grinding disc includes an opening wall at least partially defining the first opening; and wherein in at least one rotational position of the first grinding disc relative to the distance bushing, the opening wall terminates flush with a face of the distance bushing.
6. The assembly of claim 1, wherein the distance bushing has a polygonal cross-sectional shape in a plane perpendicular to the axis of the agitator shaft.
7. The assembly of claim 6, wherein the distance bushing has a square cross-sectional shape in the plane perpendicular to the axis of the agitator shaft.
8. The assembly of claim 1, wherein the first grinding disc includes a radial recess and the second grinding disc includes a radial recess.
9. An agitator ball mill, comprising: a grinding container; an inlet channel for inputting grinding stock into the grinding chamber; and an assembly including: an agitator shaft including: a first grinding disc including a first opening proximate a center of the first grinding disc, the first opening extending through the first grinding disc in an axial direction of the first grinding disc; and a second grinding disc including a second opening proximate a center of the second grinding disc, the second opening extending through the second grinding disc in an axial direction of the second grinding disc; and a distance bushing disposed between the first grinding disc and the second grinding disc of the agitator shaft, the distance bushing including an edge that sweeps over at least a portion of the first opening of the first grinding disc during rotation of the first grinding disc about an axis of the agitator shaft; and a grinding chamber formed between the grinding container and the agitator shaft.
10. The agitator ball mill of claim 9, wherein the edge of the distance bushing sweeps over an entirety of the first opening during rotation of the agitator shaft.
11. The agitator ball mill of claim 9, wherein the edge of the distance bushing sweeps over at least a portion of the second opening of the second grinding disc during rotation of the agitator shaft.
12. The agitator ball mill of claim 11, wherein the edge of the distance bushing sweeps over an entirety of the second opening during rotation of the agitator shaft.
13. The agitator ball mill of claim 9, wherein the first grinding disc includes an opening wall at least partially defining the first opening; and wherein in at least one rotational position of the first grinding disc relative to the distance bushing, the opening wall terminates flush with a face of the distance bushing.
14. The agitator ball mill of claim 9, wherein the distance bushing has a polygonal cross-sectional shape in a plane perpendicular to the axis of the agitator shaft.
15. The agitator ball mill of claim 14, wherein the distance bushing has a square cross-sectional shape in the plane perpendicular to the axis of the agitator shaft.
16. The agitator ball mill of claim 9, wherein the first grinding disc includes a radial recess and the second grinding disc includes a radial recess.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Embodiments of the present invention are described by way of example by reference to the appended drawings. In the figures:
(2) FIG. 1a shows diagrammatically in a longitudinal cross-section an agitator ball mill with a dynamic separating device which is coupled with the agitator shaft, and which comprises return channels introduced as a groove into the agitator shaft, said return channels axially extending recesses in the separating device,
(3) FIG. 1b shows diagrammatically the agitator ball mill from FIG. 1a in cross-section in the region of the separating device and in the region of the agitator shaft,
(4) FIG. 2a shows diagrammatically in a longitudinal cross-section essentially the agitator ball mill from FIG. 1a with a dynamic separating device which is coupled with the agitator shaft, and which comprises return channels introduced as a groove into the agitator shaft, said return channels axially extending recesses in the separating device, wherein the recess in the separating device is connected via a bore to the return channel,
(5) FIG. 2b shows diagrammatically the agitator ball mill from FIG. 2a in a transverse cross-section in the region of the separating device and in the region of the agitator shaft,
(6) FIG. 3a shows diagrammatically in a longitudinal cross-section an agitator ball mill with a dynamic separating device which is coupled with the agitator shaft, and which comprises return channels introduced as a groove and bore into the agitator shaft, said return channels axially extending the recesses in the separating device,
(7) FIG. 3b shows diagrammatically the agitator ball mill from FIG. 3a in a transverse cross-section in the region of the separating device and in the region of the agitator shaft,
(8) FIG. 4a shows diagrammatically in a longitudinal cross-section essentially the agitator ball mill from FIG. 1a with a dynamic separating device which is coupled with the agitator shaft, and which comprises return channels introduced as a groove into the agitator shaft, said return channels axially extending the recesses in the separating device, and an additional dynamic element,
(9) FIG. 4b shows diagrammatically the agitator ball mill from FIG. 4a in a transverse cross-section in the region of the separating device and in the region of the agitator shaft,
(10) FIG. 5 shows diagrammatically in a longitudinal cross-section an agitator ball mill with a dynamic separating device which is coupled with the agitator shaft, and which comprises return channels introduced as a groove into the agitator shaft, said return channels axially extending the recesses in the separating device, wherein the return channels run in a helical manner around the agitator shaft,
(11) FIG. 6 shows diagrammatically in a longitudinal cross-section an agitator ball mill with a dynamic separating device which is coupled with the agitator shaft, and which comprises a return channel introduced as a groove into the agitator shaft, said return channels axially extending the recesses in the separating device, wherein the return channel runs in a helical manner around the agitator shaft,
(12) FIG. 7 shows diagrammatically in a longitudinal cross-section an agitator ball mill with a dynamic separating device which is coupled with the agitator shaft, and which comprises a return channel introduced as a groove into the agitator shaft, said return channel axially extending the recesses in the separating device, wherein the return channel and the recess in the separating device run in a helical manner around the agitator shaft,
(13) FIGS. 8a-8d show diagrammatically in a transverse cross-section an agitator shaft with embodiments of the extended recess of the agitator shaft shown by way of example and
(14) FIGS. 9a-9f show diagrammatically in a transverse cross-section an agitator shaft, wherein the grinding elements are constituted as grinding discs with an opening close to the centre and distance bushings are disposed between the grinding discs.
DETAILED DESCRIPTION OF THE INVENTION
(15) Agitator ball mill 2 according to FIG. 1 comprises a grinding container 4, in which an agitator shaft 8 provided with grinding elements 6 is disposed, as a result of which a grinding chamber 10 is formed between grinding container 4 and agitator shaft 8, in which grinding chamber grinding elements 6 extend, in which at least one inlet channel 12 for grinding stock emerges and a dynamic separating device 14 for auxiliary grinding bodies is provided, wherein separating device 14 is provided with recesses 16 for the return of auxiliary grinding bodies and agitator shaft 8 is provided with groove-shaped recesses 18 extending separating device 14, said recesses extending into grinding chamber 10 in the axial direction against the product flow towards the inlet region.
(16) A static separating device constituted as a sieve 22 is disposed upstream of a product outlet channel 20. Groove-shaped recesses 18 in agitator shaft 8 run axis-parallel with the rotational axis of agitator shaft 8 and form return channels 18 for the auxiliary grinding bodies. Return channels 18 and recesses 16 in separating device 14 merge into one another, so that the auxiliary grinding bodies can take an evasive route via return channels 18 in the direction of the product inlet during operation of mill 2, arrive back in the grinding chamber and thus become distributed.
(17) Agitator ball mill 2 is designed in such a way that the stock to the ground is conveyed continuously into grinding container 4 via inlet channel 12 by means of a pump not represented here and flows in grinding chamber 10 together with auxiliary grinding bodies axially in the direction of outlet channel 20 and is thereby ground. In the region of separating device 14, the grinding stock flows with the grinding bodies through recess 16 in separating device 14. The grinding stock leaves grinding container 4 via outlet channel 20 and the auxiliary grinding bodies are moved radially outwards on account of the centrifugal forces acting on the auxiliary grinding bodies due to rotating separating device 14. The continuously conveyed grinding stock/auxiliary grinding body mixture, however, flows from outside coming from grinding chamber 10 into recess 16 of separating device 14, for which reason the return flow of the auxiliary grinding bodies is hindered. As a result of this, the auxiliary grinding bodies flow into return channel 18 in agitator shaft 8 and are then further accelerated by likewise rotating agitator shaft 8 and conveyed back into grinding chamber 10.
(18) FIG. 1b shows cross-sections of agitator ball mill 2 from FIG. 1a on the one hand in the region of separating device 14 as cross-section A-A and on the other hand in the region of agitator shaft 8 as cross-section B-B. As can be seen from the representation, separating device 14 forms a kind of cage, through recesses 16 whereof the grinding stock/auxiliary grinding body mixture can flow and is thus accelerated during operation of mill 2. The cross-sectional shape of recesses 16 corresponds to the cross-sectional shape of return channels 18 in agitator shaft 8, which have a V-shape. As a result of the angled radially running longitudinal walls 24 of channels 18 thus formed, there acts on the auxiliary grinding bodies, apart from the centrifugal force, a further radially inwardly acting force, so that the auxiliary grinding bodies are conveyed intensively into grinding chamber 10.
(19) FIG. 2a represents an agitator ball mill 2, wherein recesses 16 in the separating device are connected via an axially introduced bore 26 to return channels 18 in agitator ball mill 2. It is also conceivable for one or more return channels 18 to be constituted as a bore in a first section of agitator shaft 8. The effect of this is that the auxiliary grinding bodies flowing in channel 18 do not exit until they are in a region close to the product inlet and are conveyed into grinding chamber 10. In order to achieve the selective exit into grinding chamber 10, use can be made, instead of a bore 26, of any other kind of recess that is suitable for conveying the auxiliary grinding bodies to a region or section with an open recess 18.
(20) FIG. 2b shows cross-sections of agitator ball mill 2 from FIG. 2a on the one hand in the region of separating device 14 as cross-section A-A and on the other hand in the region of agitator shaft 8 as cross-section B-B. Bore 26, as a connection between recess 16 of the separating device and return channel 18, is introduced at an angle as viewed in the axial direction. This section of separating device 14 thus additionally acts as a pump for the auxiliary grinding bodies, which as a result of this pumping effect are sucked out of the region of separating device 14 in order that the auxiliary grinding bodies are conveyed into the grinding chamber in a region of agitator shaft 8.
(21) An agitator ball mill 2 with a separating device 14 as represented in FIG. 2a is shown in FIG. 3a. Agitator shaft 8 comprises return channels 18 through axially running bores 28 in agitator shaft 8, said return channels being interrupted in sections and, as in the case out a return channel 18 introduced as a groove, are open towards grinding chamber 10. Bores 28 in the agitator shaft are introduced at an angle as viewed in the axial direction, like bores 26 of separating device 14, and act as a pump. The auxiliary grinding bodies can take an evasive route into the grinding chamber in the open sections of return channels 18.
(22) FIG. 3b shows cross-sections of agitator ball mill 2 from FIG. 3a on the one hand in the region of separating device 14 as cross-section A-A and on the other hand in the region of agitator shaft 8 as cross-section B-B.
(23) FIG. 4a shows essentially agitator ball mill 2 from FIG. 1a with a dynamic separating device 14 which is coupled with agitator shaft 8, and which comprises return channels 18 introduced as a groove into agitator shaft 8, said return channels axially extending recesses 16 of separating device 14, and an additional dynamic element 30, which is provided with radially running channels or wings. Outlet-side end section 32 of mill 2 and adjoining additional dynamic element 30 run conically towards one another, as a result of which a gap 34 is formed, which generates a flow in the radial direction towards dynamic separating device 14. In contrast with agitator ball mill 2 shown in FIG. 1a, return channel 18, on the product-inlet side as viewed in the axial direction, is closed by a wall 36. By means of wall 36, disadvantageous flowing of the material to be ground into return channel 18 from the product inlet side can be counteracted.
(24) FIG. 4b shows cross-sections of agitator ball mill 2 from FIG. 4a on the one hand in the region of separating device 14 as cross-section A-A and on the other hand in the region of agitator shaft 8 as cross-section B-B. Recesses 16 in separating device 14 are introduced at an angle as viewed in the radial direction, as a result of which an additional pumping effect is generated radially outwards. With a relatively high throughput rate, a sufficiently strong counter-flow can thus be generated in order to convey the auxiliary grinding bodies radially outwards, in order that the latter can pass via return channel 18 back into grinding chamber 10.
(25) Agitator ball mill 2 with an agitator shaft 8 with return channels 18 running in a helical manner in the axial direction, said return channels being introduced as a groove into agitator shaft 8, is represented in FIG. 5. In this embodiment, a flow in the axial direction towards the product inlet is also generated as a result of the helical course of channels 18. Recesses 16 of separating device 14, on the other hand, are introduced axis-parallel with the rotational axis of agitator shaft 8.
(26) FIG. 6 represents an agitator ball mill 2 as already shown in FIG. 5. In this embodiment, however, agitator shaft 8 comprises only one return channel 18, which is also coupled with only one recess 16 of separating device 14. It is however also conceivable to introduce between recesses 6, 18 a recess running in the circumference into separating device 14 or into agitator shaft 8. The auxiliary grinding bodies could thus be conveyed from all recesses 16 in separating device 14 via the connecting recess into return channel 18.
(27) Return channel 18 could however also be introduced in a helical form continued over the separating device 14. Such an embodiment is represented in FIG. 7. Separating device 14 comprises only one recess 16, which transforms into return channel 18.
(28) FIG. 8 show in cross-section by way of example various embodiments of agitator shaft 8. In particular, reference is made to FIG. 8d, wherein agitator shaft 8 comprises recesses 18, but the latter are not constituted as channels 18 as in the figures described above. A kind of return channel 18 is formed by the rotation of agitator shaft 8 during operation of mill 2. On account of a continuous displacement of the grinding stock/auxiliary grinding body mixture, a similarly constituted grinding chamber 10 arises as with an agitator shaft 8 with a return channel 18, wherein the auxiliary grinding bodies can flow back beneath grinding chamber 10.
(29) Grinding discs 38 as grinding elements with at least one opening 40 close to the centre are represented in FIG. 9. Distance bushings 42 are disposed between grinding discs 38. Grinding discs 38 and distance bushings 42 are braced axially and form, together with an inventive dynamic separating device not represented here, an agitator shaft.
(30) Each grinding disc 38 in FIGS. 9a to 9d is provided with a total of four openings 40, through which auxiliary grinding bodies can flow back. The shapes of the grinding discs are illustrated by the dashed line and distance bushings 42 have a polygonal cross-section. Openings 40 are introduced into grinding disc 38 in such a way that a lower opening wall 44, as represented in FIGS. 9a, 9b, 9c, terminates flush with a face 46 of distance bushing 42. Distance bushings 42 are constituted such that their edges completely sweep over openings 40 during rotation of agitator shaft 8. In FIG. 9d, on the other hand, distance bushing 42 projects, as viewed in the axial direction, into opening 40, so that opening 40 is swept over only partially during rotation of agitator shaft 8.
(31) It has been shown in practice that, as a result of the arrangement of openings 40 close to the centre, the auxiliary grinding bodies are transported particularly effectively back into the grinding chamber.
(32) A grinding disc 38 with a distance bushing 42 with a square cross-section is represented in FIGS. 9a, 9c, 9d, wherein grinding disc 38 in FIG. 9c additionally comprises a total of 4 radial recesses 48. FIG. 9b shows a grinding disc 38 with a triangular shape and flattened or rounded-of corners, wherein distance bushing 42 has in cross-section a shape corresponding to grinding disc 38.
(33) FIGS. 9e and 9f show by way of example further inventive embodiments and arrangements of a grinding disc 38 with an opening 40 close to the centre and a distance bushing 42. The variants represented in FIG. 9 are not exhaustive, in particular a combination of different grinding discs 38 and distance bushings 42 is conceivable, as long as an inventive return flow of the auxiliary grinding bodies is ensured.
(34) Agitator ball mill 2 is specifically aimed at an effective distribution of the auxiliary grinding bodies in grinding chamber 10. Due to the fact that the auxiliary grinding bodies are conveyed in the axial direction along agitator shaft 8 from separating device 14 back into grinding chamber 10, an increased concentration of auxiliary grinding bodies in the region of separating device 14 is prevented.
(35) Furthermore, unground product that flows close to the centre along agitator shaft 8 from the inlet region of agitator ball mill 2 in the axial direction towards separating device 14 is also conveyed in the radial direction back into grinding chamber 10, into an outer more effective grinding region. In the case of an agitator ball mill 2 with grinding discs 38, this effect becomes particularly marked in the case of grinding discs 38 with a radial recess 48, since unground product can flow back close to the centre in the axial direction in particular through recesses 48 in grinding disc 38. The risk of unground product thus passing into outlet channel 20 is minimised by the pumping effect of distance bushings 42.
