EP0645179B1 - Grinding mill and mixer containing said grinding mill - Google Patents

Description

The invention relates to a grinder according to the preamble of claim 1 and a mixer according to claim 10.

EP-A-0 200 003 discloses such a mill, which is designed as a pin mill and can be used in a mixer. The rotor is provided with vanes which are arranged such that they can be driven in rotation within a stator. The stator is provided with pins, between which and the radially outer ends of the blades shear gaps are formed.

From DE-B-1 176 614 a mixing turbine with a winged rotor is known, which is surrounded by a guide ring serving as a stator at the same height. The guide ring has window-like openings through which at least part of the material to be mixed is ejected radially. In order to be able to change the overlap of the blades with the window-like openings, the impeller and the guide ring are axially adjustable relative to one another.

From DE-C-40 28 108 a pin mill for mixers is known which has a rotor consisting essentially of blades which are arranged within an annular stator. The rotor and the stator each have teeth distributed around the circumference, which mesh with one another when the rotor rotates.

The mills mentioned above are used in particular for the defined distribution of viscous, that is to say flowable, materials on mixed materials. At the same time, they serve to break up mixed agglomerates again. The aforementioned purposes are satisfactorily achieved in numerous applications; for extremely sensitive mix, especially for Appropriate fluid distribution, however, these effects are not achieved satisfactorily.

From GB-A-1 305 402 a mixing device is known which has an impeller as a rotor and a stator. The inner surface of the stator tapers in the shape of a truncated cone from the mixture inlet side to the mixture outlet side. The stator is provided with passage slots above the rotor.

A mixing device for stirring and homogenizing liquids is known from DE-A-38 20 271. It has a rotor with vanes which is arranged in a stator which has an inner surface which tapers in the shape of a truncated cone. The liquids to be mixed enter the stator from the larger diameter side of the inner surface and are discharged to the outside through a bore which cuts through the inner surface which tapers in the shape of a truncated cone. The side of the stator assigned to the smaller diameter side of the inner surface is designed to be closed.

The invention has for its object to design a grinder of the generic type so that an excellent mixing and disagglomerating effect is achieved even under extreme conditions.

This object is achieved in a attritor according to the preamble of claim 1 with the features in the characterizing part of claim 1. The frustoconical design of the friction surface ensures that the friction surface has an extension from the mixture inlet side to the mixture outlet side that is greater than the distance from the inlet side to the outlet side, thereby increasing the friction and thus mixing and deagglomerating effect . Furthermore, the taper exerts a force on the material to be mixed, which counteracts the conveying of the material to be mixed from the inlet side to the outlet side, as a result of which the residence time of the material to be mixed in the region of the rotor and thus the mixing and deagglomeration effect is increased. The liquid is added where it is immediately triturated with the mix, ie solid, so that agglomerates do not form in the first place, which then have to be ground again.

The measures according to claim 2 lead to a particularly intensive mixing and deagglomeration effect, claim 3 indicating optimal cone opening angles for the friction surface. Claim 4 specifies optimal ranges for the ratio of the rotor diameter to the axial extent of the rotor.

Claims 5 to 7 contain an extremely simple possibility of adjusting the gaps between the rotor and the friction surface resulting from the frustoconical configuration of the friction surface. Claims 8 and 9 represent particularly advantageous and inventive measures for supplying liquid into the region of the frustoconical friction surface.

Claims 10 and 11 reflect the use of an attrition mill according to the invention in a mixer which can be operated continuously or discontinuously.

Fig. 1

einen vertikalen Längsschnitt durch einen Mischer,

Fig. 2

einen Querschnitt durch den Mischer entsprechend der Schnittlinie II-II in Fig. 1,

Fig. 3

einen Teilschnitt durch Fig. 1 entsprechend der Schnittlinie III-III,

Fig. 4

eine Draufsicht auf die Reib-Mühle entsprechend dem Sichtpfeil IV in Fig. 3,

Fig. 5

einen Teilschnitt durch eine weitere Ausführungsform einer Reib-Mühle in einer Darstellung entsprechend Fig. 3 und

Fig. 6

eine Draufsicht auf die Reib-Mühle gemäß dem Sichtpfeil VI in Fig. 5.

Further features, advantages and details of the invention result from the following description of exemplary embodiments with reference to the drawing. It shows

Fig. 1

a vertical longitudinal section through a mixer,

Fig. 2

2 shows a cross section through the mixer according to section line II-II in FIG. 1,

Fig. 3

1 according to the section line III-III,

Fig. 4

a plan view of the grinder according to the arrow IV in Fig. 3,

Fig. 5

a partial section through a further embodiment of a grinder in a representation corresponding to FIGS. 3 and

Fig. 6

a plan view of the grinder according to the arrow VI in Fig. 5th

The largely conventional mixer shown in the drawing has a horizontal, stationary, cylindrical container 1, which is closed at the end and held at the same time by side walls 2, 3 acting as stands. On the side walls 2, 3, bearing blocks 4 are fastened, in which a shaft 5 of a mixer 6, which is arranged concentrically to the container 1, is mounted. It is driven by a drive motor 7 via a V-belt drive 8 and a gear 9. The mixing mechanism 6 has mixing tools 10 which are designed in the form of blades and are held by means of mixing tool carriers 11 which are attached to the shaft 5 and project radially therefrom. The mixing tools 10 themselves are located near the inside of the wall 12 of the container 1.

wobei gilt

W =

Umfangsgeschwindigkeit der radial äußeren Enden der Mischwerkzeuge 10 in m/s

R =

Radius des Mischwerks 6 in m

g =

Erdbeschleunigung in m/s².

On the top of the container 1, a material inlet 13 is arranged; a material outlet 14 is provided on the underside. The mixer will Operated in batches as a so-called turbulent mixer, ie it is a throwing mixer in which the individual mixed material particles are thrown up and return to a mixed material bed on a parabolic trajectory. In order to achieve this effect, the mixing tools 10 are driven at a supercritical peripheral speed, which - expressed in the dimensionless Froude index - is approximately Fr = 2-6. The Froude key figure is defined $${\text{Fr = W}}^{\text{2nd}}\text{: R xg}$$

where applies

W =

Circumferential speed of the radially outer ends of the mixing tools 10 in m / s

R =

Radius of the mixer 6 in m

g =

Acceleration due to gravity in m / s ² .

In the wall 12 of the container 1, a so-called grinder 15 is installed, which is described in detail below. On the outside of the wall 12 of the container 1, specifically in the area below the shaft 5 (see FIG. 2), a flange bearing 16 is attached, to which a motor 17 is flanged. A clutch 18 connects the output shaft of the motor 17 to a drive shaft 19 of the grinder mill 15. This drive shaft 19 passes through the wall 12. The flange bearing 16 of the motor 17 is supported on a mill base plate 22 via bearing supports 20 and a flange ring 21. The entire grinder 15 is attached to this mill base plate 22. The mill base plate 22 is fastened in and in front of an opening 23 of the wall 12.

The grinder 15 has a stator 24 and a rotor 25 on its side of the base plate 22 facing away from the motor 17. The stator 24 consists essentially of a stator ring 26 which has a cylindrical outer surface 27 and a frustoconical inner friction surface 28. The side of the ring 26 facing the base plate 22 forms a mixed material inlet side 24a and the side facing away from the base plate 22 forms a mixed material outlet side 24b. The inner friction surface 28 tapers from the entry side 24a to the exit side 24b of the grinder 15 at a half cone opening angle α of 20 ° to 45 ° and preferably 30 °. The stator ring 26 is supported by two support rods 29 with respect to the base plate 22, which are arranged in a radial plane to the shaft 5, so that they do not represent an effective obstacle for mixing tools 10, as can be seen in particular from FIG. 1. They are therefore also in a common plane with the axis 30 of the drive shaft 19.

Within the inner friction surface 28, the stator ring 26 is completely open in the direction of the axis 30, which is also the axis of the inner friction surface 28. Only two lugs 29a for the support rods protrude slightly into the open cross section.

The rotor 25 is designed like a propeller. It has a sleeve-shaped hub 32, which is connected in a rotationally fixed manner to the drive shaft 19 by means of a feather key 31 and to which vanes 33 with a radius c and an axial extent d, which extend approximately radially outward, are attached. These wings 33 have the cross section of an elongated rectangle and are arranged radially to the axis 30. They are - as can be seen in particular from FIG. 4 - inclined or adjusted with respect to the axis 30 in such a way that - in relation to the direction of rotation 34 of the rotor 25 - the lower edge 35 of each wing 33 adjacent to the base plate 22 leads and that of the base plate 22 facing away from the upper edge 36. As a result, the blades 33 exert on conveying material a conveying pulse directed in the direction of the axis 30 away from the base plate 22 towards the free end of the grinder 15, on which a conveying pulse directed radially to the axis 30 towards the friction surface 28 is superimposed.

The blades 33 are provided at their radially outer ends with shear edges 37 which run parallel to the inner friction surface 28 of the stator ring 26 and which limit the narrow shear gap 38 with respect to the inner friction surface 28, the width b of which is therefore constant over the length of the shear gap 38 . For width b, 0.5 mm ≤ b ≤ 3.0 mm usually applies.

On the drive shaft 19, in the area in which it passes through the base plate 22, a sealing sleeve 39 is attached, against which seals 40, 41 bear, which in turn are supported in a through-bore 42 in the base plate 22. Between the seals 40 and 41, a grease chamber 43 is formed, through which a grease connection 44 grease for lubricating the seals 40, 41 can be introduced.

A spacer sleeve 45 bears against the sealing sleeve 39, which is supported on its other side against the hub 32 of the rotor 25, 45 spacer disks 46 being arranged between the hub 32 and the spacer sleeve. By adding or removing a spacer 46, the position of the rotor 25 in the direction of the axis 30 is changed, as a result of which the width b of the shear gap 38 is changed or set. A cup-shaped fastening sleeve 47 bears against the hub 32 from the free end of the rotor 25, which is connected by means of a cap nut 48 to a threaded pin 49 of the drive shaft 19 and the hub 32 with the wings 33 in the direction of the axis 30 Base plate 22 firmly clamped against the spacer sleeve 45 with the spacer washers 46.

A liquid feed device 50 is assigned to the grinder 15, which has a tubular base body 51 which is inserted into a through-bore 52 in the base plate 22 running parallel to the axis 30. A liquid supply connection 53 opens into this tubular base body 51 on the side of the base plate 22 facing away from the stator 24 and rotor 25. On the side of the base body 51 facing the rotor 25, a spray valve 54 opens out from the latter, which is a commercially available spray valve 54 which only opens when liquid under pressure is supplied via the supply connection 53, and this closes when no more liquid is supplied under pressure. The distance e of the outlet opening 55 of the valve 54 from the adjacent edge 35 of the wings 33 is very small, namely as small as is structurally possible. The distance e is therefore in the range between 0.5 and 3.0 mm. The average distance f of the outlet opening 55 from the axis 30, ie the distance of the axis 56 of the valve 54 from the axis 30 of the drive shaft 19 is more than half of the maximum radius c of the rotor 25, the valve 54 with its Exit opening 55 is to be arranged radially as far as possible on the outside with respect to the axis 30, ie close to the inner friction surface 28 and thus the shear gaps 38. Since the valve 54 is arranged in a common plane with the support rods 29, the lugs 29a and the drive shaft 19 is a certain distance from the shear gaps 38 is unavoidable for design reasons.

The mechanism of action is as follows:
The mixing material in the container 1 is circulated and mixed by the mixing tools 10 of the mixing unit 6 and also shifted parallel to the axis 57 of the shaft 5. It is brought into the space 58 between the base plate 22 and the rotor 25 and is fed to the rotor 25. The mixed material is gripped by the vanes 33 and, on the one hand, conveyed in the manner described in the direction of the tapering inner friction surface 28 and at the same time flung radially outward to the axis 30 and fed to the shear gaps 38. Because on the one hand the inner friction surface 28 is at least largely closed radially to the axis 30 to the outside and because the inner friction surface 28 tapers in the axial conveying direction 59 of the vanes 33, the material to be mixed is stowed in the stator 24 and not merely in the direction 59 the grinder 15 flung through. Because it is simultaneously conveyed radially outwards, it is subjected to an intensive friction-shear stress in the shear gaps 38. At the same time, the liquid is introduced into the mix through the outlet opening 59 and immediately thereafter enters the shear gap 38. As a result, no agglomerates of the mix can form, not even with very fine mix on the one hand and highly viscous, strongly adhesive liquids on the other. The liquid is applied to the individual mix particles in a very finely divided form. So there is no macro-mixing of mix and liquid with simultaneous agglomerate formation, but a micro-mixing.

The embodiment according to FIGS. 5 and 6 differs from that according to FIGS. 3 and 4 with regard to the construction of the rotor and stator only in constructive details, which are not important here. Identical parts are therefore provided with identical reference numerals as in FIGS. 3 and 4, while functionally identical but structurally slightly different parts are designated with the same reference number, but additionally with a prime, without requiring a new description in both cases. The embodiment of FIGS. 5 and 6 differs from that of FIGS. 3 and 4 by the type of Hydration. Here, a feed housing 60 is attached to the mill base plate 22 'by means of screws 61, into which a liquid feed connection 53' opens radially. From the supply housing 60, which surrounds the drive shaft 19 'with the sealing sleeve 39' in a stationary manner, liquid is supplied via a radial channel 62 in the sleeve 39 'and the drive shaft 19' to an axial channel 63 which runs concentrically to the axis 30 in the drive shaft 19 ' . This axial channel 63 ends in the region of the rotor 25 'in radial outlet channels 64, which are arranged as bores adjacent to the lower edge 35 in the wings 33' and end with their outlet openings 55 'in the respective shear gap 38 or in the vicinity of the shear gap 38 .

Alternatively, the radial outlet channels 64 ′ can be designed as tubes separate from the vanes 33 ′, which also protrude into the vicinity of the inner friction surface 28 and release the liquid there in the direction of the inner friction surface 28. In all the cases described, the liquid is thus added in such a way that, together with the mixture, it must migrate over most of the inner friction surface 28 from its inlet side 24a as its wider area to its outlet side 24b as its narrower area.

Claims (11)

1. A grinding mill

   - comprising a mill base plate (22, 22')

   - comprising a motor (17) connected with the base plate (22, 22')

   - comprising a drive shaft (19, 19') coupled with the motor (17) and drivable for rotation about an axis (30)

   - comprising an annular stator (24) connected with the base plate (22, 22'), having an inner face (28) arranged concentrically of the axis (30) and being open within the inner face (28), and which comprises a mixing stock inlet side (24a) facing the base plate (22, 22') and a mixing stock outlet side (24b) spaced in the direction of the axis (30)

   - comprising a rotor (25, 25') non-rotatably connected with the drive shaft (19, 19'), provided with wings (33, 33') which extend as far as into the vicinity of the inner face (28), formed to be open between the wings (33, 33') and, at the radially extreme ends of the wings (33, 33'), having edges (37) which extend substantially parallel to the inner face (28) and

   - comprising a liquid supply arrangement (50, 50'), the liquid outlet (55, 55') of which is directed directly into the area of the stator
   characterized in
   that the inner face of the stator (24) is formed as a grinding face (28) which tapers in the shape of a truncated cone in the direction from the mixing stock inlet side (24a) towards the mixing stock outlet side (24b) and
   that the liquid outlet (55, 55') of the liquid supply arrangement (50, 50') is arranged to be directly adjacent to the mixing stock inlet side (24a) of the stator (24).
2. A grinding mill according to claim 1, characterized in that the grinding face (28) is formed to be closed.
3. A grinding mill according to claim 1 or 2, characterized in that the grinding face (28) is inclined in relation to the axis (30) at half an angle of taper (a), to which applies: 20° ≤ a ≤ 45°.
4. A grinding mill according to one of claims 1 to 3, characterized in that the rotor (25, 25') has a maximum radius (c) and, in the vicinity of its radially outer edges (37), an extension (d) in the direction of the axis (30), to the relation d/c of which applies:
   0.4 ≤ d/c ≤ 0.6.
5. A grinding mill according to one of claims 1 to 4, characterized in that the radially extreme edges (37) of the wings (33, 33') each delimit a shearing gap (38) towards the grinding face (28).
6. A grinding face according to claim 5, characterized in that the width (b) of the shearing gaps (38) is adjustable.
7. A grinding mill according to claim 6, characterized in that the rotor (25, 25') is adjustable in the direction of the axis (30) in relation to the stator (24).
8. A grinding mill according to claim 1, characterized in that the liquid supply arrangement (50) comprises at least one spray valve (54) arranged directly in front of the mixing stock inlet side (24a).
9. A grinding mill according to claim 1, characterized in that the liquid supply arrangement (50') comprises a channel (63) guided through the drive shaft (19') and at least one outlet channel (64, 64') which is connected with the drive shaft (19') and extends as far as into the vicinity of the grinding face (28).
10. A mixer comprising a grinding mill according to one of claims 1 to 9, a cylindrical receptacle (1) and a mixing unit (6) arranged to be rotatably drivable therein, the mill base plate (22, 22') being arranged in a wall (12) of the receptacle (1), the motor (17) being arranged outside of the receptacle (1) and the rotor (25, 25') and the stator (24) within the receptacle (1).
11. A mixer according to claim 10, wherein the mixing unit (6) comprises a shaft (5) and mixing tools (10) which are connected therewith and are rotatably drivable in proximity to the wall (12) of the receptacle (1) and wherein the mixing tools (10) can pass between the wall (12) of the receptacle (1) on the one hand and the rotor (25, 25') and the stator (24) on the other hand.

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