WO2006111380A1

WO2006111380A1 - Grinding device

Info

Publication number: WO2006111380A1
Application number: PCT/EP2006/003617
Authority: WO
Inventors: Roland Reichardt; Wolfgang Wiechert
Original assignee: Universität Siegen
Priority date: 2005-04-20
Filing date: 2006-04-20
Publication date: 2006-10-26
Also published as: DE102005018400A1; EP1879698A1; DE102005018400B4

Abstract

The invention relates to a grinding device comprising a grinding container provided with at least one grinding mill having at least one rotor which is fixed to a shaft that can be driven by means of a motor and is used to accelerate a plurality of grinding bodies arranged in the grinding container. Said grinding container (B) has a non-circular cross-section at least in a partial region perpendicular to the longitudinal axis (4) of the grinding container, which extends especially parallel to a shaft (5). The invention also relates to a grinding container, especially for using in one such grinding device.

Description

grinder

The invention relates to a grinding apparatus comprising a grinding container, which comprises at least one grinder with at least one rotor mounted on a shaft driven by a motor for accelerating a plurality of grinding bodies provided in the grinding container.

Such grinding devices are known in the art, often used as grinding media balls. In many cases, such a grinding device is used to further reduce an already powdered material in its grain size, the grinding process is essentially based on that in the grinding container accelerated by the rotor grinding media such as the aforementioned balls collide with each other in many cases and thereby arranged between these grinding media materials pound. It can be produced in this way grain sizes down to the nanometer range. Such devices are not only suitable for further grinding of powders, but in principle the use in liquids, e.g. Suspensions, be possible. In that regard, the pumps are suitable both for dry grinding and wet grinding.

In order to accelerate the grinding bodies provided in the grinding container to high speeds, it is essentially provided to arrange one or more rotors, which rotate in the grinding container at high speed, on one or more shafts, which may each be motor-driven.

BESTATIGUNGSKOPIE Often 8 to 20 meters / second peripheral speed is reached, preferably the speed is greater than 10 meters / second. In this case, the rotors extend from the drive shaft to the vicinity of the container wall, wherein a gap between the rotor tip and container wall remains.

Due to the large number of grinding media in a grinding container, therefore, a grinding body will repeatedly collide with a rotor or a rotor blade or blade of such a rotor and be accelerated by this collision. The thus accelerated grinding bodies repeatedly collide against each other or even to the wall of the grinding container, so that the ground material is crushed.

The grinders known in the prior art essentially have grinding containers which, at least perpendicular to the longitudinal axis of the grinding container, which is often preferably parallel to a shaft, have a circular cross-section. Accordingly, grinding containers are substantially cylindrical, frusto-conical or baliig, since all of these forms above are structurally particularly easy to manufacture.

In the known grinding devices in which e.g. the container volume in a vertical arrangement up to 80% and in a horizontal arrangement up to 40% with grinding media, such as. Spheres can be filled, there is the problem that the collision of the grinding media with a rotor essentially the grinding media are accelerated outward towards the container wall, where they slow down due to impact processes and then in a collection of a variety of Move Mahlkörpern inside along the container wall, in particular roll along with balls.

Thus, in the wall region of a grinding container, there are grinding media accumulations in which the individual grinding media have only a very small velocity component with respect to one another and the total accumulation of grinding media is essentially undisturbed on the grinding media Container wall moved along. By the rotation of the rotor, the Mahlkörperansammlung receives a direction of movement that corresponds to that of the rotor.

Due to this movement, centrifugal forces continue to arise, which cause the grinding bodies to always be accelerated in the direction of the grinding container wall due to their movement, so that there is only a slight probability, especially at high speeds, that a grinding body moving in the region of a container wall will make its way back to the container Rotor passes, again collided with the rotor and is accelerated again.

In practice, it has been observed that all of the grinding media of such a generic grinding apparatus are with high probability in the region of the inner wall of the grinding container and the grinding media density in the center of the mowing device, in which at least one shaft is arranged with at least one rotor, or at least the environment of a rotor is very low.

The object of the invention is to provide a grinding device and a grinding container which can be used for such a grinding device, by means of which it can be achieved that the milling efficiency is significantly increased, in particular at the same rotor speed.

According to the invention, this is achieved by a grinding container or a mowing device with such a grinding container, which has a cross-section deviating from the circular shape perpendicular to at least in a partial region extending in particular parallel to a shaft Mahlbehälterlängsachse.

As already mentioned in the discussion of the prior art, the concentration of the grinding media in the region of the inner wall of the grinding container is essentially due to the centrifugal forces which act when the multiplicity of grinding media adhere to the inner wall of the grinding chamber Move along the grinding container, this effect is essentially supported by the circular cross-sectional shape of a grinding container perpendicular to the Mahlbehälterlängsachse or to the driving rotor shaft.

According to the invention, as a result of the fact that the grinding container has a cross-section which deviates from the circular shape, at least in partial regions perpendicular to the longitudinal axis of the grinding container, it is possible for the grinding bodies, such as e.g. Spheres, due to their movement experience a force and thus an acceleration, which causes due to their deviation from the direction of the centrifugal force that a grinding body moves away from the inner wall of the grinding container.

Already by the deviation from the circular shape is caused when a movement of a grinding body along the inner wall of the container not only exclusively a centrifugal force acting in the radial direction, but also in the direction deviating forces, due to which a grinding body in the direction of the interior of the container and thus in the direction of a rotor or its shaft is effected. In this case, the force that results from impact processes between the grinding bodies is not considered in the first place.

In a preferred embodiment, this is achieved particularly effectively if the grinding container has a cross-section that differs from the circular shape not only in a partial region but over its entire length perpendicular to the longitudinal axis of the grinding container, in particular parallel to a shaft. In this case, this cross-section may be rotationally symmetrical, for example, relative to the container longitudinal axis, but this is not necessary for achieving the effects of the invention.

The preferred effect to be achieved is that, during the movement of a grinding body, forces act on the grinding body, which can move this grinding body in the direction of a rotor or in the direction of the interior of the grinding container can be achieved structurally in almost manifold manner, if the inner surface of the grinding container at least in a partial region has a shape which deflects a grinding body moving along this inner surface, in particular a rolling ball, such that its speed vector has a radial component.

The shaping of the body will preferably be such that the velocity vector points in particular in the direction of the interior of the grinding container and thus significantly deviates significantly from the exclusively tangential direction of the velocity vector, which is usually given for grinding containers of circular cross section.

By means of the shaping according to the invention of a grinding container and in particular its inner wall, it is achieved that the multiplicity of grinding bodies are not merely moved in the immediate inner wall region of the grinding container wall, but are repeatedly accelerated in the direction of the interior of the container due to the disturbance caused by the shaping. This significantly increases the probability that a grinding body accelerated in the direction of the interior will collide again with the rotating rotor or a rotor blade or wing of this rotor and thus be accelerated again to high speeds. Accordingly, by means of the shaping according to the invention of a grinding container, the number of grinding bodies with a high relative speed to each other increases significantly.

In a structurally easy to manufacture embodiment of the grinding container mold according to the invention, it can be provided that the inner surface of the grinding container has a particular periodic waveform. Such a waveform may be cosine or sinusoidal, for example, but it is essential that such a periodic waveform can be achieved, for example, that the distance between a rotor shaft or the shaft axis and the inner surface of the grinding container at least in a partial area, in particular However, over the entire grinding container length, the container longitudinal axis or by one or more waves is angle-dependent.

This angular dependence can basically be of any type, wherein it is preferably provided that the angular dependence is periodically formed, in particular wherein an angular period 360 degrees through n and n is an integer, in particular with n equal to 3. Accordingly, particularly preferred effects result and effective accelerations of the grinding media in the direction of the interior of the grinding container, when the grinding container not only has a deviating from the circular cross-section, but in particular a deviating from the elliptical cross-section.

The inventive, deviating from a circular cross-sectional shape of a grinding container can be formed not only in that the grinding container in its manufactured form has the desired cross-section throughout and thus, for. is also rotationally symmetrical, but already characterized in that the grinding container, and in particular a grinding container having a substantially cylindrical, conical or spherical shape on its inner surface at least one, preferably more and more preferably evenly distributed evenly or non-uniformly, inwardly facing elevations. These elevations are according to the invention designed such that a grinding body, which comes in contact with such a survey on its trajectory, is directed back into the interior of the grinding container due to its deflected by means of elevation movement path.

It can therefore be provided, already on the production side such surveys that provide for a deflection, in particular of the usually adjusting tangential trajectory of a grinding body, which are molded directly into the Mahlbehälterwandung at least inside or even such that such surveys subsequently on the inner wall of a Be applied container. Accordingly, such elevations can be formed, for example, in the form of a bulge in the Mahlbehälterwandung or else be secured inside the Mahlbehälterfläche in the form of baffles or baffles. Thus, such a baffle or such a deflecting element can be introduced in particular on the attachment also subsequently to the existing grinding devices in the grinding media to optimize even existing existing grinding devices. Thus, in particular existing grinding devices can be optimized, the grinding container in a known manner having a cylindrical, conical or spherical shape.

Inwardly into the grinding container facing elevations on the inside of the Mahlbehälterwandung may have any shape. For example, they may themselves be wall-shaped and thus e.g. serve as a baffle or it is also possible to form the elevations spherical segment and thus create elevations on the inside of the grinding container, which have a spherical surface substantially. It is important for the effect according to the invention, in essence, that the elevations of the usually present tangential trajectory of a grinding body in the region of the grinding container wall oppose an obstacle which has a significant deflection of the trajectory and thus a deviation from the typical circular path.

An embodiment of the invention is shown in the following figures. Show it:

Figure 1 is a cross section perpendicular to the longitudinal axis of an inventive

grinder

Figure 2 shows an enlarged detail of the wall portion of a grinding device with a grinding container according to the invention Figure 3 is a perspective view of a grinding container according to the invention

FIG. 1 shows a preferred cross-sectional shape of a grinding container B according to the invention for a grinding device, which can be embodied, for example, as a so-called stirred ball mill, in which balls are accordingly used as the grinding element, which can be accelerated by a rotor 1 shown here in two-lobes. In the figure 1 has been omitted to illustrate the inventive shape on the representation of the plurality of balls as grinding media.

It can be seen that the container wall has a periodic waveform, which in the present example has a periodicity of 360 degrees by 6. Specifically, the mathematical representation of the cross-section satisfies the formula rho (phi) = cos (phi ^* n) ^* (R-r) + R. Here, rho is the distance between the axis 4 of the driving shaft 5 of the rotor 1 and the container inner wall, where this distance of the formula is angle dependent, and this angle is given by the magnitude phi in the range of 0 to 360 degrees. n is the periodicity and here chosen to be n = 6, where furthermore r represents the minimum desired distance between the shaft axis 4 and the container inner wall and R the mean distance.

In the embodiment chosen here, care must be taken that the radial extension of a rotor blade 1 from the shaft axis 4 is smaller than the minimum distance between the shaft axis 4 and container inner wall, in order to prevent the rotor 1 abutting against the inner wall.

With the container shape according to the invention, which in principle can also obey other periodic functionalities, is achieved by the rotor 1 accelerated balls or ball accumulations that roll along the inner wall of the container B and thus always have a tangential to the wall velocity component, always in the points or an environment of the minimum radial distance of the inner wall of the shaft 5 from the container wall lift so that their speed component also has a radial component with respect to the rotor shaft.

Deviating from the usual circular cross-sectional shape of a container B, in which a velocity vector of a rolling on the inside of a ball 3 always forms only a tangent to the circular cross-section, here is a shaping, in which a velocity vector in some areas of the inner wall and secants to the container shape or its Cross section forms. Due to the fact that a velocity vector forms a secant to the container shape, it can be seen that the undisturbed trajectory of such a ball 3 or generally such a grinding body not only always along the inner wall, but can also lead in the direction of the interior of the container B.

Thus, due in particular to the fact that a ball deflected in this way collides with further balls, there is an increased probability, with respect to the known state of the art, that balls from the region of the inner wall will always return to the inner central regions of the shaft 5 and thus of the accelerating rotor 1 are deflected so as to record via a collision with a rotor blade 1 again kinetic energy. By means of the shaping according to the invention can thus be achieved that significantly the relative velocity between different grinding media and in particular the balls can be increased, which has a significant effect on the grinding efficiency, without the rotor speed and possibly without the electrical power, such as the driving electric motors , must be increased.

The shape shown here, in cross-section in FIG. 1 and in a perspective view in FIG. 3, is preferred insofar as it is a rotationally symmetrical cross-sectional shape relative to the shaft axis 4, the production technology is easy to produce. The cross-sectional shape shown here does not limit the invention, but it can also be achieved starting from a circular cross-sectional shape by the attachment of surveys or other disturbing bodies, surfaces or elements on the inside of a wall, the effect of the invention.

2 shows an enlarged detail of the lower wall portion of the above-described container according to the invention B according to the figure 1, wherein it is shown here that a ball 3 rolls on the inside of the container wall 2. This representation represents a simplification, since in practice not a single ball 3, but substantially a plurality of balls 3 along the container inner wall 2 at the same time along rolls.

In FIG. 2 it is shown that in a further preferred embodiment it can be provided that with respect to the horizontal H, the tangent T on the inner wall 2 of the container assumes an angle α greater β, where β is referred to as the angle of repose. This is the angle at which a powdery material automatically moves due to the gravitational effect, so that it can be achieved here that by means of the grinding process crushed powder which accumulates in the region of the inner wall 2, always in the direction of a lowermost portion of a in this Representation horizontally oriented grinding container accumulates and can be removed there at a removal opening from the grinding device. Accordingly, it is provided according to the invention that the tangents T at the container inner wall 2 below the height halving shaft axis 4 with respect to the horizontal H always occupy an angle which is greater than the angle of repose. Excluded from this validity is an environment around the lowest point removal opening.

The observation of the angle of repose is advantageous if a hole for the removal of the ground material in the lower area is arranged in a horizontally oriented grinding container. If the powdery millbase at a Dry process pneumatically or the material to be ground in a wet process is hydraulically blown or pumped from the grinding device, it is not necessary to pay attention to the angle of repose.

Claims

claims

1. Grinding device comprising a grinding container, which has at least one grinder with at least one rotor mounted on a motor driven shaft for accelerating a plurality of provided in the grinding container grinding bodies, characterized in that the grinding container (B) at least in a partial region perpendicular to , In particular parallel to a shaft (5) extending Mahlbehälterlängsachse (4) has a deviating from the circular cross-section.

2. Grinding device according to claim 1, characterized in that the

Grist container (B) over its entire length perpendicular to, in particular parallel to a shaft (5) extending Mahlbehälterlängsachse (4) has a deviating from the circular cross-section.

3. Grinding device according to one of the preceding claims, characterized in that the inner surface (2) of the grinding container (B) at least in a partial region has a shape, which on this inner surface (2) along moving Mahlkörper (3), in particular a rolling ball (3) deflects such that its / its speed vector has a radial component, in particular in the direction of the interior of the grinding container (B) shows.

4. Grinding device according to one of the preceding claims, characterized in that the inner surface (2) of the grinding container (B) on the inside has a particular periodic waveform.

5. Grinding device according to one of the preceding claims, characterized in that the distance between a rotor shaft (5) or the shaft axis (4) and the inner surface (2) of the grinding container (B) at least in a partial area, in particular over the entire Grist container length is dependent on angle.

Ü. iviαi IIVCΓΠCI tion πacn rvnsprüCu 5, uuuurcu yθKθππΣβiCurϊθi, usss uie angle dependence is periodic, in particular wherein an angular period 3607n and n is an integer, in particular with n> = 3

7. Grinding device according to one of the preceding claims, characterized in that the grinding container (B), in particular a grinding container having a substantially cylindrical, conical or spherical shape, on its inner surface at least one, preferably several, more preferably more evenly or non-uniformly distributed inwards has pointing survey / s, in particular such that a grinding body, in particular a ball is directed by means of a survey in the direction of the interior of the grinding container.

8. Grinding device according to claim 7, characterized in that a survey is formed from:

a. a molded into the Mahlbehälterwandung bump and / or

b. a deflector / baffle mounted inside the grinding container surface.

9. A method for optimizing grinding devices, in particular whose grinding container has a cylindrical, conical or crowned shape, characterized in that a grinding container (B) is modified by mechanical deformation and / or by incorporation of deflecting / baffles on the inner surface of the grinding container such that the grinding container at least in a partial region perpendicular to, in particular Having parallel to a shaft extending Mahlbehälterlängsachse a deviating from the circular cross-section.

10. Grinding container, in particular for use in a grinding device according to one of the preceding claims 1 to 8, characterized in that the grinding container at least in a partial region perpendicular to, inchocnnrloro nα rαllol -i \ ι αinαr \ Λ / αllα (KI / orlαnfαnrlon

Mahlbehälterlängsachse (4) has a deviating from the circular cross-section.