EP0474102B1 - Method and device for grinding and intensive mixing bulk material and/or liquids with different pouring capability, density or viscosity for obtaining homogeneous mixtures - Google Patents

Abstract

The mixing components are mixed within a vessel (1) by means of mixing tools (5) and grinding elements (7), and the mixing components are subjected to a forced compression by being passed through a mill consisting of at least two concentric grinding elements (8, 9) which are freely mobile relative to one another, and at least one grinding element causes the product motion in the axial and radial directions, while at least one other grinding element allows only axial flow. <IMAGE>

Description

The invention relates to a method for grinding and intensive mixing of bulk goods and / or liquids, in which the mixture components are mixed in a container by means of mixing tools and comminuted in a rotor / stator mill arranged in the container, according to the preamble of claim 1, and a device to carry out this method according to the preamble of claim 3.

When manufacturing mixed goods in the pharmaceutical, cosmetic, chemical, plastic and food industries as well as related areas, the aim is always to have a homogeneous structure of the mixed material.

For this purpose, mixers are known which consist of an actual mixing drum in which a shaft is arranged centrally, on which mixing elements are fastened. This shaft with the mixing elements is driven by a drive system, usually consisting of an electric motor, V-belt drive and reduction gear. Due to the special shape of the mixing elements and their arrangement on the shaft, the mix is whirled intensively. In order to improve the degree of homogenization, it is known in the case of mixers of the type mentioned at the outset to arrange mills transversely to the axially extending mixing elements, to which the mixing components are fed through the mixing elements. So-called knife mills or rotor / stator mills are used here. Rotor / stator mills are based on the principle of forced reduction in that the components are broken up, defibrated and dispersed. The knife mills are based on the principle of impact crushing, whereby the components are broken up, defibrated, dispersed and compressed.

DE-OS 37 28 710 describes a mixer which has a shredder arranged on the container wall. The purpose of this shredder is to ensure that a shear effect is obtained during shredding in order to prevent or dissolve lumps when mixing and drying, for example, extremely moist mixed materials.

According to DE-OS 37 28 710, the rotor and stator of the shredder are flowed through both radially and axially, which results in unsatisfactory mixing results, in particular due to the flowability of the stator. This deficiency can be caused by the measure additionally proposed in this step, that of forming the radial arms of the rotor in a twisted manner for the purpose of an axial conveying effect, cannot be eliminated, since a considerable proportion of the mixed material can nevertheless escape radially through the stator.

DE-OS 15 07 889 discloses a method for operating mixing machines and an associated mixing machine with a built-in mill consisting of a rotor and a stator. The mix is swirled in this built-in mill by means of rotor knives; however, due to the lack of counter edges for the rotor knives, there is no shearing effect on the mix. Even if the stator of this state of the art cannot be flowed through radially due to its closed design, a mixing result in need of improvement is obtained since the material to be mixed is only swirled by the rotor knives and is not ground.

Based on this prior art, the invention has for its object to provide a method and an apparatus of the type mentioned, in which the mixture in the rotor / stator mill arranged in the container is positively guided and forcibly subjected to a shear effect, and thus reliable and is ground and / or mixed thoroughly.

This object is achieved by a method according to claim 1 and by a device according to claim 3.

A preferred variant of the method according to the invention results from claim 2, preferred embodiments of the device according to the invention are specified in claims 4 to 12.

According to the invention, a generic method is improved in such a way that the mix in the rotor / stator mill experiences a forced pressing through a grinding gap formed by intermeshing intermeshing rotor and stator teeth, the inner grinding element forming the rotor and the outer grinding element forming the stator , and the mixed material does not flow through the outer grinding element in the radial direction.

A mixture component can preferably be passed from the outside, through the mill, in which the forced pressing takes place, into the container.

A device of the type mentioned at the outset is designed according to the invention in such a way that the inner grinding element forms the rotor and the outer grinding element forms the stator of the mill, the mixed material cannot flow radially through the outer grinding element, and that the rotor and the stator each have teeth distributed circumferentially. they mesh with each other and form a grinding gap for forcing the mixed material through.

Preferred embodiments of the device according to the invention are described below:
The teeth of the rotor and the stator preferably have a trapezoidal shape, as a result of which they automatically form cutting edges.

The inner grinding element is preferably designed as a rotor, which has at least two vanes which are positioned in relation to the longitudinal axis of the mill, so that the mix is specifically transported in the axial direction. Depending on the application, the transport direction can change.

It makes sense to manufacture the grinding elements from particularly wear-resistant material.

By means of fastening means, for example by means of two bolts, the stator can be screwed to an installation flange, at least one of these bolts being drilled through in the longitudinal direction, so that liquid or a mixture component can be transported from the outside into the mixing area.

The mill can expediently be driven at a variable speed, so that the grinding process can be adapted to the particular mix.

A preferred embodiment of the stator and the rotor provides that they are designed to open conically in the transport direction, or that the stator and rotor are designed to taper in the transport direction.

The stator is preferably designed as a jacket to prevent radial flow through.

The grinding elements of the stator shaped as teeth can be formed by the arrangement of preferably semicircular notches.

The invention will now be explained in more detail with reference to the accompanying drawings, which show particularly preferred exemplary embodiments of the invention.

Fig. 1:

Eine perspektivische Darstellung eines an sich bekannten Mischers, in den die erfindungsgemäße Mühle eingebaut ist;

Fig. 2:

den Rotor-/Statorkopf der Mühle in zusammengebautem Zustand;

Figur 3 bis 6:

Den Rotor in verschiedenen Ansichten

Figur 7 bis 9:

Den Stator in verschiedenen Ansichten.

Show:

Fig. 1:

A perspective view of a mixer known per se, in which the mill according to the invention is installed;

Fig. 2:

the rotor / stator head of the mill in the assembled state;

Figure 3 to 6:

The rotor in different views

Figure 7 to 9:

The stator in different views.

FIG. 1 shows the perspective view of a mixer 1 known per se. This has a mixing drum 2 which is closed on both sides by end walls 3. A shaft 4 is located centrally, on which a multiplicity of mixing elements 5 are arranged. The mixing elements 5 are welded to the shaft 4 or screwed into pockets welded to the shaft. The shaft 4 with the mixing elements 5 is driven by an electric motor 6. The mix is already whirled through this arrangement. The rotor / stator mill 7 according to the invention is preferably installed in the lower drum area. This mill 7 or its rotor / stator head is now described in more detail in FIG.

The mill 7 consists essentially of a rotor 8 and a stator 9, which have a common geometric axis 10. The stator 9 has a toothing 12 corresponding to the toothing 11 of the rotor 8, such that corresponding radial inlets 18 are formed between the toothing 12, in which the toothing 11 of the rotor 8 can rotate. A special feature of the invention is that the material to be mixed can only flow axially through the stator in the gap 14 between the stator teeth 12 and the rotor teeth 11, since the stator is closed radially.

The stator 9 is screwed to an installation flange 16 by means of two bolts 15. For example, it is possible to provide one or both of these bolts with a through-bore 17 so that liquid or another component can be transported from the outside into the grinding area.

Figures 3 to 6 show the rotor according to the invention in different views.
FIG. 3 shows a side view of the rotor 8 with the hub 19 cut open.
FIG. 4 shows a view of the rotor 8 from the direction F indicated in FIG. 3.
FIG. 5 shows a top view of the rotor 8 from the direction G indicated in FIG. 4 and FIG. 6 shows a section along the line AA indicated in FIG. 5.

The exemplary embodiment according to FIGS. 3 to 6 shows a rotor with four blades 13 which are offset radially by 90 ° and are arranged diagonally to the axis 10 on the hub 19. The wings 13 are designed such that they also have teeth 11 arranged one behind the other in an offset corresponding to the diagonal or oblique offset to the hub 19. The number of teeth 11 depends on the material to be mixed. The rotor 8 has a central bore 21 for receiving the drive shaft 20 shown in FIG. 2, a groove 22 being inserted for a feather key.

FIGS. 7 to 9 show the stator 9, FIG. 7 a section along the section line CD indicated in FIG. 8, FIG. 9 a section along the line EE shown in FIG. 8 and FIG. 8 a section along the line indicated in FIG Show line AB.

Of particular note in these representations are the circular passage gaps 14 or radial inlets 18.

The present invention proposes a method and a device with which homogeneous mixes can be created.

Reference list

1.

mixer

2nd

Mixing drum

3rd

End walls

4th

wave

5.

Mixing elements

6.

Electric motor

7.

Mill

8th.

rotor

9.

stator

10th

Longitudinal axis of 7

11.

Teeth (rotor)

12th

Teeth (stator)

13.

wing

14.

Passage gaps

15.

bolt

16.

Mounting flange

17th

Piercing

18th

Radial notches

19th

hub

20th

drive shaft

21.

Shaft drilling in 19th

22.

Groove

Claims (12)

1. A method for the grinding and intensive mixing of bulk materials and/or liquids with different pouring behaviour, density or viscosity, in which the mixture components are mixed in a container by means of mixing implements and are comminuted in a rotor/stator mill which is additionally arranged in the container and which substantially comprises an inner grinding element and an outer grinding element which are arranged concentrically to one another and are rotatable relative to one another, wherein the inner grinding element forms the rotor and the outer grinding element forms the stator and the mixing material is conveyed in axial and radial direction by the inner grinding element and is conveyed at least in axial direction by the outer grinding element, characterised in that
   in the rotor/stator mill the mixing material is constrained to undergo being forced through a grinding clearance formed by means of mating intermeshing rotor and stator toothing, and wherein the mixing material cannot flow through the outer grinding element in radial direction.
2. A method according to Claim 1, characterised in that one mixture component is directed from the outside into the container through the mill in which the constrained passage takes place.
3. An apparatus for the grinding and intensive mixing of bulk material and/or liquids with different pouring behaviour, density or viscosity, for carrying out the method according to either Claim 1 or Claim 2, having a container and a shaft (4) preferably mounted concentrically in the container, mixing implements (5) being secured to arms projecting radially from the shaft (4), with at least one rotor/stator mill (7) which is disposed in the container in the vicinity of the container wall and which substantially comprises an inner rotor (8) and an outer stator (9) as grinding elements which are disposed concentrically to one another and are also rotatable relative to one another, wherein the mixing material can be conveyed by the inner grinding element in axial and radial directions, and can be conveyed at least in axial direction by the outer grinding element, and with a distance from the grinding elements to the container wall which, during operation, makes possible the movement of at least one mixing implement (5) at least partly through between the container wall and the grinding elements, characterised in that the mixing material cannot flow radially through the outer grinding element, and in that the rotor (8) and the stator (9) each have peripherally spaced apart teeth (11, 12) which mate in an intermeshing manner and form a grinding clearance (14) for the constrained passage of the mixing material.
4. An apparatus according to Claim 3, characterised in that the teeth (11, 12) are trapezium-shaped and serve to form cutting edges.
5. An apparatus according to Claim 3 and at least one of the preceding claims, characterised in that the rotor (8) has at least two blades (13) which are so positioned with respect to the longitudinal axis (10) of the turbomill (7) that the mixing material undergoes a controlled transport component in axial direction.
6. An apparatus according to Claims 3 to 5, characterised in that the grinding elements (8, 9) are produced from particularly wear-resistant material.
7. An apparatus according to Claims 3 to 6, characterised in that an inlet for another component is provided from the outside into the stator and/or rotor zone.
8. An apparatus according to Claims 3 to 7, characterised in that the stator (9) is screwed by fastening means, preferably two fastening bolts (15), to a mounting flange (15) and for the purpose of supplying liquid from the outside into the grinding zone and/or for the inlet of a further mixture component at least one of these bolts has a through-bore (17) in longitudinal direction.
9. An apparatus according to Claims 3 to 8, characterised in that the mill (7) can be driven at variable speed.
10. An apparatus according to Claim 3 and at least one of the preceding claims, characterised in that the stator (9) and/or the rotor (8) is/are designed to open conically in transport direction.
11. An apparatus according to Claim 3 and at least one of the preceding claims, characterised in that the stator (9) and/or the rotor (8) are designed to taper in transport direction.
12. An apparatus according to Claim 3 and at least one of the preceding claims, characterised in that the grinding elements of the stator (9) are in the form of teeth (12) formed by the arrangement of preferably semicircular indentations (18).

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