CN110893367B

CN110893367B - Stirring shaft for a stirred ball mill, stirred ball mill and method for producing a stirring shaft for a stirred ball mill

Info

Publication number: CN110893367B
Application number: CN201910832708.6A
Authority: CN
Inventors: L·弗莱萨; U·恩德勒; H·默舍尔
Original assignee: Netzsch Feinmahltechnik GmbH
Current assignee: Netzsch Feinmahltechnik GmbH
Priority date: 2018-09-13
Filing date: 2019-09-04
Publication date: 2022-03-18
Anticipated expiration: 2039-09-04
Also published as: DE102018122395A1; CH715322A2; CH715322B1; CN110893367A

Abstract

The invention relates to an agitator shaft for an agitator ball mill, wherein the agitator shaft has a longitudinal axis and an outer side equipped with agitator elements, wherein the agitator shaft is formed in one piece with the agitator elements and is made of a ceramic material. The invention also relates to a method for producing a stirring shaft for a stirred ball mill.

Description

Stirring shaft for a stirred ball mill, stirred ball mill and method for producing a stirring shaft for a stirred ball mill

Technical Field

The invention relates to a stirring shaft for a stirred ball mill, a stirred ball mill and a method for producing a stirring shaft for a stirred ball mill according to the features of the independent claims.

Background

The invention relates to a stirring ball mill, in particular to a stirring tool for the stirring ball mill. Stirred ball mills are apparatuses for coarse, fine and ultra-fine comminution or homogenization of grinding stock. Agitator bead mills are composed of vertically or horizontally arranged, mostly approximately cylindrical milling containers, 70% to 90% of which are filled with milling bodies. In stirred ball mills, the grinding containers are usually mounted in a stationary manner. Many conventionally known mills fill through a central opening in one of the end walls. Alternatively, the filling can also take place directly via the grinding cylinder. The product to be ground flows continuously axially through the grinding chamber from the product inlet to the product outlet during the grinding process. The solid material suspended in this way is comminuted or dispersed by impact forces and shear forces between the grinding bodies. The grinding aid bodies are then separated from the product flow in the discharge region. The discharge takes place according to the design and is, for example, discharged through a sieve at the end of the mill.

The stirring tool is usually formed by a stirring tool shaft for rotating a stirring element in the form of a disk or a radially projecting pin, in particular for scattering and comminuting solid material of the grinding material distributed in the liquid. The stirring tool shaft is typically driven by a motor. A disk agitator having a plurality of milling disks arranged on an agitator shaft is used in particular as a suitable agitator element. The grinding discs are mostly circular and may have through holes. The product flow is ensured in particular via the through-openings.

An annular grinding gap is formed between the inner side of the grinding cylinder and the agitator tool, in which grinding material to be comminuted is located during operation of the agitator ball mill. The stirring tool is driven in rotation and exerts a stress on the ground material within the grinding gap, thereby comminuting the ground material, which is assisted on the one hand by the grinding aid bodies and on the other hand by the stirring element of the stirring tool. In particular, the grinding material and the grinding aids are moved intensively by means of the stirring shaft. In this connection, the solid material particles of the grinding material are comminuted by impact, pressure, shearing and friction.

The stirring shaft or stirring tool is preferably made of a wear-resistant material, in particular a metal or ceramic material, for example WO2000/054884a describes a stirred ball mill, in which the stirring tool, in particular a disk-type stirring element, is made of a ceramic material. DE2626757a1 discloses a stirrer propeller which is constructed such that only relatively simple and inexpensive components are subject to wear and that these components can be easily replaced. It can be economical here for these simple components to be made of particularly wear-resistant materials, for example ceramics.

Many chemical, mechanical or other processes are carried out with the generation of process heat which can have a detrimental effect on the process itself or on the raw materials used, since for example the substances involved in the process are temperature sensitive or temperature changes have an effect on the process speed and thus the process is difficult to carry out in an ordered manner. The process is thereby generally stabilized, for example by removing the process heat generated by means of a suitable cooling device or cooling method. The process processes which are carried out in the containers are in this case mostly tempered via the container wall, for example by means of a cold or hot water pipe which extends over the wall or by means of a further outer container which is arranged radially spaced apart from the first container and surrounds the first container, so that a cavity is formed between the two containers, through which a fluid flow, which may be a hot water flow or a coolant flow, can pass in order to transport process heat.

Heat is also generated during the milling process. Depending on the product, heat must be removed or heat formation must be prevented. The problem is in particular that in stirred ball mills large milling volumes are desired or higher efficiencies are desired. For cooling during the grinding process, the grinding cylinder is, for example, designed to be coolable. For example, publication DE 3614721 a1 describes the construction of a grinding container with a cooling jacket as prior art. The document also discloses that the stirring tool rotor may also be provided with at least one cooling channel on its circumference. Furthermore, a milling container with a cooling jacket is shown in publication WO 2007/042059 a 1. The agitator tool mill described in this document also has an inner stator, which can likewise be cooled. The stirring tool is configured in a basin shape and comprises a cylindrical rotor.

As described in the context of DE 3614721 a1, cooling may alternatively or additionally also be achieved via the stirring tool rotor. The publication DE 3015631 a1 describes a stirring tool which is composed of an inner cylinder and an outer cylinder, between which an annular cooling space is formed, wherein pipes for conveying a coolant are arranged in parallel with their axes within the cooling space for cooling, which pipes are connected to a conveying pipe for the coolant.

Another coolable stirring shaft is known from DE10241924B3, in which tubular materials of different cross-sectional shapes are used for cooling purposes, an inner tube is arranged in the interior thereof, which inner tube extends over approximately the entire length, the inner space of the tube being connected to a coolant inflow and the outer space being connected to a coolant outflow.

Starting from a certain structural size, a stirring shaft or stirring tool made of ceramic must be composed of a plurality of components. In order to produce the individual parts in a matched manner, a large number of grinding operations are required, which is very costly due to the required operating time. Furthermore, when the mixing shaft is assembled from a plurality of components, so-called dead spaces are created, in which grinding material and/or grinding aids can become stuck and thus contaminate the machine space. Such multi-piece ceramic shafts are also very susceptible to breakage, particularly during installation, disassembly, cleaning and maintenance. Furthermore, it has not been possible to produce ceramic rotors with cooling devices.

Disclosure of Invention

The aim of the invention is to produce a stirring shaft for a stirred ball mill, in particular a coolable stirring shaft for use in high-performance stirred ball mills, in a simple and cost-effective manner.

The above object is achieved by a stirring shaft for a stirred ball mill, a stirred ball mill and a method for producing a stirring shaft for a stirred ball mill comprising the features in the independent claims. Further advantageous embodiments are described in the dependent claims.

The agitator ball mill is used for processing and in particular comminuting grinding stock by means of grinding aids and has a grinding container with a grinding stock inlet and a product outlet, the grinding container being provided with an agitator tool, which is arranged at least partially within the grinding container.

The stirring tool comprises a drive device, a stirring shaft arranged on the drive device and rotating in a direction of rotation, and at least one stirring element arranged on the stirring shaft. The stirring shaft has a preferably cylindrical base body with a longitudinal axis, wherein at least one stirring element, preferably a plurality of stirring elements, is arranged on the base body. In particular the stirring shaft has an outer side provided with stirring elements. The longitudinal axis of the stirring shaft generally coincides with the longitudinal axis of the milling container. The drive device is usually arranged outside the grinding container and is connected to a stirring shaft arranged inside the grinding container via a drive shaft which penetrates the container wall.

The milling container is preferably of cylindrical design and is arranged horizontally or vertically, so that the stirring shaft is arranged horizontally or vertically, respectively. The milling container can also have other configurations and can be configured, for example, as a truncated cone. In this case, the stirring shaft is preferably likewise embodied in the form of a truncated cone.

The at least one stirring element is configured, for example, as a cam, which preferably extends approximately in the circumferential direction away from the stirring shaft in the direction of the inside of the milling container of the stirred ball mill.

An annular grinding gap is formed between the outer side of the stirring shaft and the inner side of the grinding container, and a mixture of grinding material and grinding aid bodies is located in the grinding gap. Due to the rotation of the stirring shaft, the milled material within the milling gap is comminuted due to stresses, for example by the particles colliding with one another, due to shear forces or the like. The additional energy introduced by the stirring element, in particular acting on the milling aid body, assists the comminution operation.

The stirring shaft is formed in one piece with the stirring element and is made of a ceramic material. Particularly preferably, the stirring shaft is made of silicon carbide (SiC), silicon carbide with free silicon (SiSiC), silicon nitride, zirconium dioxide or mixed ceramics. Silicon carbide ceramics have high wear resistance, low thermal shock sensitivity, low thermal expansion, high thermal conductivity, good acid and alkali resistance and are lightweight and retain their advantageous properties at temperatures above 1400 ℃. In addition, silicon carbide is toxicologically harmless and can therefore also be used in the food industry. Although the hardness of silicon nitride is reduced compared to silicon carbide, by the sintering process, columnar recrystallization of the β -silicon nitride crystal can be achieved, which leads to an increase in the fracture toughness of the material. The combination of high fracture toughness and small defect size makes silicon nitride one of the highest strength engineering ceramic materials. Silicon nitride ceramics are particularly useful for thermal shock stress components due to a combination of high strength, low coefficient of thermal expansion, and relatively low modulus of elasticity. Zirconium dioxide has a very high resistance to crack propagation compared to other ceramic materials. In addition, zirconia ceramics have a very high thermal expansion, and so one would prefer to choose when making a connection between the ceramic and the steel.

It is particularly preferred to produce the stirring shaft with stirring elements by means of a 3D printing method. In this way, components with an internal cavity can be produced which cannot be produced in one method step by conventional methods, such as casting, without further post-treatment, such as subsequent introduction openings, etc. But in this case at least one integrated cooling channel can be formed within the stirring shaft simply and cost-effectively. Preferably, the cooling channel extends at least partially parallel to the longitudinal axis of the stirring shaft. According to one embodiment, it is provided that at least one cooling channel is designed to be meandering, for example at least two regions of the cooling channel each extend parallel to the longitudinal axis of the mixing shaft, wherein a deflecting region is formed between two parallel regions.

According to one embodiment of the invention, two areas which extend in parallel and through which the coolant flows in opposite flow directions are located on a common radius of the stirring shaft. Thereby achieving convective cooling of the stirring shaft. In particular, the coolant is guided from the grinding material inlet side to the product outlet side in each case close to the longitudinal axis of the stirring shaft. The return flow of the coolant from the product outlet side to the grinding material inlet side takes place inside the stirring shaft in a region adjacent to the outer side of the stirring shaft. This achieves that the most recent and therefore the coldest coolant is initially introduced into the hottest region of the milled material of the agitator ball mill. This is in particular the region close to the product outlet after the milled material has flowed through the agitator ball mill in the conveying direction from the milled material inlet side. In particular, the coolant therefore flows through the stirring shaft at the surface of the stirring shaft in the opposite direction to the conveying direction of the grinding stock through the stirred ball mill. The cooling process can be further optimized by means of this convective cooling.

The stirring shaft is embodied in such a way that it comprises at least two partial sections, in particular a first partial section at the end, on which the stirring shaft is connected to the drive shaft of the stirring tool. For example, the first partial section at the end has a receiving region, in particular a bellows, in which the free end of the drive shaft is arranged and connected to the agitator shaft in a rotationally fixed manner. Furthermore, at least one second subsection is provided. The second subsection is preferably hollow in its interior. In addition, a through-opening is preferably formed in the second subsection between the outer lateral surface and the hollow interior or the interior region. In particular, a plurality of through-openings are provided, which extend parallel to the longitudinal axis of the stirring shaft. A separating device can preferably be formed in the interior of the second subsection. The grinding material/grinding aid body mixture flowing through the grinding gap is diverted at the open end of the second partial section and flows via the separating device into the hollow interior of the second partial section. The separating device, which may be embodied as a sifting device or classifying rotor, in particular intercepts the grinding aid bodies and conveys them back into the grinding gap through the through-openings together with the possibly not yet sufficiently comminuted grinding material. The fully comminuted ground material is then conducted via the hollow interior to the product outlet of the agitator ball mill and can be removed there.

Preferably, the milling aids accumulate in a so-called milling chamber, since the milling gap between the stirring shaft and the inner wall of the milling container is very small. Only a small part of the grinding aid bodies is diverted together with the grinding material and passed through the separating device, for example, in the hollow interior of the second subsection.

According to one specific embodiment, the second subsection is a central subsection to which a third, further subsection is connected at the end. The third subsection likewise has a hollow interior. In the case of a cylindrical basic body of the stirring shaft, the inner space of the second partial section and, if appropriate, of the third partial section is preferably likewise of cylindrical configuration and has a circular cross section, wherein the radius of the cross section of the inner space in the third partial section is greater than or equal to the radius of the cross section of the inner space in the second partial section. Furthermore, the inner hollow spaces, which are designed as cylinders, each have a longitudinal axis, which is designed to coincide with the longitudinal axis of the stirring shaft.

In the third subsection, preferably no through-openings are provided between the interior and the outer side of the stirring shaft. Alternatively, an anti-wear protective sleeve can be arranged in the interior of the third subsection, which is preferably likewise of cylindrical design. In particular, the wear-resistant protective sleeve is arranged between the container bottom of the grinding container and the separating device in the region of the second interior space. In this embodiment, the grinding material/grinding aid mixture flowing through the grinding gap is diverted at the open end of the third partial section and guided within the annular gap formed between the wear-resistant protective sleeve and the stirring shaft in the direction of the second partial section, which is achieved as described above by separating the grinding material from the grinding aid bodies.

Preferably, it is provided that the at least one cooling channel extends within the first partial region at the end and at least partially within the intermediate second partial region. In an embodiment of the stirring shaft comprising three subsections, it can be provided that at least one cooling channel extends through all three subsections. The meandering cooling channel may comprise, for example, parallel sections which are each formed between the through-openings within the second subsection of the stirring shaft. The parallel section may extend at least partially into the first and/or third subsections of the stirring shaft. In particular, corresponding deflecting regions are formed at the end regions of the first and third partial sections of the mixing shaft, which deflecting regions deflect the coolant from one parallel section into the next, so that the coolant preferably flows in each case in opposite directions through the parallel sections arranged directly adjacent to one another.

In particular, it is provided that such a cooling channel comprises an even number of parallel sections, so that the coolant inlet and the coolant outlet are each located at the same end of the stirring shaft. In this case the coolant flows for example in a first flow direction through the first, third and fifth parallel sections etc. and in a second, opposite flow direction through the second, fourth and sixth parallel sections etc. The milled material/milling aid mixture flows through the milling gap in a first conveying direction, which corresponds for example to the first flow direction and is diverted in particular within the second and/or third partial section of the stirring shaft into a second conveying direction, which corresponds to the second flow direction. The cooling water guide, in particular the cooling water supply line and the discharge line, can be formed by an insert which is arranged, for example, together with the drive shaft on the first subsection of the mixing shaft and can be fixed thereto; for example, the insert part can be inserted onto the end of the drive shaft and arranged together with the drive shaft and fixed in the bellows bush, wherein the cooling water inlet line and the outlet line are connected to at least one cooling channel of the mixing shaft.

A plurality of stirring elements is preferably arranged on the stirring shaft. The regular arrangement of stirring elements, which are arranged in a row and/or in series one after the other, in particular parallel to the longitudinal axis of the stirring shaft, is arranged along a circumferential line of the basic body of the stirring shaft. In this case, all stirring elements can be of identical design or can also have different shapes. In addition, a region in which more cams or the like are formed than in other regions may be provided on the stirring shaft.

The stirring element is preferably designed as a cam which projects from the base body of the stirring shaft, wherein the connection surface of the cam designed on the base body is relatively large, in particular greater than the height of the cam which projects beyond the base body in the radial direction.

The cam has a connecting surface formed on the base body of the stirring shaft, an upper side facing the inside of the milling container, a side which is forward in the rotational direction of the stirring shaft, a side which is rearward in the rotational direction of the stirring shaft, and two sides which are arranged between the forward side and the rearward side. The front side is also referred to as the inflow side and the rear side is also referred to as the side facing away from the flow. The distance between the connecting surface and the upper side is referred to as the cam height.

Heat can advantageously be dissipated from the milled material/milling aid body mixture via the relatively large connecting surface of the cam into the mixing shaft and in particular into the coolant inside the at least one cooling channel of the mixing shaft. The cam shape described in detail below reduces the susceptibility of the ceramic material to fracture or breakage. The base body and the cam are jointly produced as a single component from a ceramic material, in particular by means of a 3D printing method, so that a direct material connection between the base body and the cam of the mixing shaft is produced. The one-piece embodiment of the stirring shaft promotes stability and thermal conductivity, since potential fracture points and thermal barriers are eliminated.

For good stability of the cams and for achieving a uniformly good grinding effect, it is advantageous if each cam has a connecting surface with the base body of the mixing shaft and a front side, wherein the ratio of the projection of the front side on a plane perpendicular to the base body of the mixing shaft to the size of the connecting surface is less than 1.

The front side is hereinafter referred to as the end-side current surface. The angle of inclination of the end-side current surface with respect to a plane perpendicular to the base body is preferably in the range from 45 ° to 85 °. An angle of 0 ° corresponds here to a current surface arranged perpendicular to the base body, while an angle with a minus sign indicates a lateral current surface, i.e. the current surface is inclined such that it appears to cover a certain region of the connecting surface. The angle of inclination with a plus sign therefore indicates an end-side current surface which is inclined to the opposite, i.e. the end of the current surface which is located on the substrate is flowed through first.

It has furthermore been found to be advantageous if the connection surface of each cam to the stirring axle has a maximum width and the ratio of the height of each cam perpendicular to the stirring axle to the maximum width is greater than 0.2. The connecting surface just mentioned corresponds in particular to the base surface of each cam and is the surface of each cam which is in contact with the stirring shaft. It has also been found to be advantageous if the connection surface of each cam to the agitator shaft has a maximum length and the ratio of the height to the maximum length of each cam is less than 1.

It is also advantageous if the connection surface of each cam to the mixing axis has a maximum length and a maximum width, wherein the ratio of the maximum width to the maximum length is less than 1.

If a plurality of cams are arranged in succession in a row along the circumference of the basic body of the mixing shaft in the circumferential direction of the basic body of the mixing shaft, it can be advantageous, for example, if the spacing between successive cams in the circumferential direction in a row is selected to be equal to or greater than the maximum length of the cams in the circumferential direction. If a plurality of cams are arranged in each case in rows one behind the other along a plurality of circumferential lines spaced apart from one another in the axial direction, it can be advantageous if the axial distance between every two axially spaced-apart cam rows is greater than or equal to 1.1 times the maximum width of the cams. In the case of a stirring shaft with a base body on which the cams are arranged at a distance from one another in the axial direction, it can be provided that the cams are arranged axially aligned with one another or offset from one another.

As described above, an abrasion-proof protective sleeve can be arranged in the third end-located subsection of the stirring shaft, in particular in the region of the third interior space, and can be installed within the stirred ball mill in such a way that it can be easily replaced.

The wear protection casing is at least partially of cylindrical design, in particular of hollow cylindrical design. The hollow cylinder has an outer diameter that is less than the inner diameter of the third interior cavity region. A fastening region, for example a flange, can be provided on an end region of the wear protection sleeve in order to position and fasten the wear protection sleeve in or on the agitator ball mill.

In particular, the stirring shaft in turn forms a grinding gap between an inner side of the third interior space or interior space region and an outer side of the preferably cylindrical wear protection sleeve, in which the grinding material/grinding aid mixture is guided in the direction of the second interior space region of the second subsection. The wear protection sleeve is preferably likewise made in one piece and in particular from a ceramic material and can be produced analogously to the stirring shaft, for example in a 3D printing method.

It can also be provided that the wear protection casing comprises at least one cooling channel, which is likewise designed, for example, to be meandering and thus to form a large cooling surface. The outer side of the wear protection sleeve can likewise be configured with a cam-like projection. The shape of the projection may for example correspond to the shape of the aforementioned cam arranged on the stirring axle. The projection reduces the clearance between the inner side of the stirring shaft in the third cavity area and the outer side of the wear-resistant protective sleeve. The projections serve in particular as scrapers, in order to prevent the grinding material and/or the grinding aids from adhering to the inner side of the stirring shaft. Alternatively, it is ensured by the projection that the grinding material/grinding aid body mixture flows in the direction of the through-opening in order to return the grinding aid bodies in the direction of the grinding chamber formed between the outer lateral surface of the stirring shaft and the inner wall of the grinding container.

The wear protection sleeve is preferably usable in combination with the aforementioned stirring shaft in a stirred ball mill. The wear protection sleeve may also be used in combination with a stirring shaft made according to conventional methods. In this context, it is emphasized that the single-piece design with or without projections formed on the outer side and/or with or without the wear protection of the at least one cooling channel is a separate invention.

The aforementioned one-piece stirring shaft configured with cams or the like and at least one cooling channel combines the advantages of optimal cooling with maximum wear resistance and is therefore particularly suitable for application in high-performance mills.

The invention also comprises, in particular, a stirring shaft of one-piece construction and in particular made of ceramic material, which is constructed without cooling channels. Preferably, the mixing shaft also has at least two subsections of different design, in particular at least one first subsection at the end and at least one second subsection for fastening the mixing shaft to the drive shaft, at least one second subsection having an inner space region of hollow design and a passage opening in the second subsection between the inner space region and the outer side of the mixing shaft.

It should be emphasized here that all variants and variants described in relation to the device according to the invention can equally relate to part of the method according to the invention. The same therefore applies to the method according to the invention, when particular aspects and/or relationships and/or functions are mentioned here in the description or in the claims for the device according to the invention. On the contrary, the same holds true, so that all variants and variants described in relation to the method according to the invention can equally relate to partial variants of the device according to the invention. The same therefore applies to the device according to the invention, when particular aspects and/or relationships and/or functions are mentioned here in the description or in the definitions of the claims for the method according to the invention.

Drawings

Embodiments of the invention and their advantages are explained in detail below with reference to the drawings. The dimensional ratios of the individual elements in the figures do not always correspond to the actual dimensional ratios, since some shapes are shown simplified and others are shown enlarged for better illustration than others.

Figure 1 shows a perspective view of an embodiment of a stirring axle according to the invention constructed in one piece,

figure 2 shows a side view of the stirring shaft according to figure 1,

figure 3 shows a sectional view of the stirring shaft along section line a-a according to figure 2,

figure 4 shows another section of the stirring shaft along section line B-B according to figure 3,

figure 5 shows a perspective technical view of the stirring shaft,

figure 6 shows a sectioned mixing shaft with exposed serpentine cooling channels,

figure 7 shows a side view of the wear protection sleeve,

figure 8 shows a perspective view of the wear protection sleeve,

figure 9 shows a front view of a stirred ball mill,

figure 10 shows a cross-section of the stirred ball mill along section line a-a according to figure 9,

figure 11 shows a cross-section of the stirred ball mill along section line B-B according to figure 10,

figure 12 shows a cross-section of the stirred ball mill along the section line C-C according to figure 11,

figure 13 shows a cross-section of the stirred ball mill along section line D-D according to figure 12,

figure 14 shows a cross-section of the stirred ball mill along the section line E-E according to figure 9,

fig. 15 shows a perspective view of another embodiment of a stirring axle according to the invention, constructed in one piece, with convection cooling means,

figure 16 shows a longitudinal cross-section of a stirred ball mill with cooling channels configured as convective cooling means,

figure 17 shows a cross section along section line a-a of the stirred ball mill according to figure 16 with a stirring shaft,

fig. 18A to 18E respectively show other embodiments of the stirring shaft.

The same reference numerals are used for the same elements or elements having the same function of the present invention. Furthermore, for the sake of clarity, only the reference numerals necessary for the description of the respective figures are shown in the respective figures. The illustrated embodiments are merely examples of an implementation of a device according to the invention or a method according to the invention and these examples are not intended to be limiting.

Detailed Description

Fig. 1 to 6 show different views and sectional views of a stirring shaft 1 according to the invention in one-piece construction. Such a stirring shaft 1 is preferably used in a stirred ball mill 50 as explained in detail below with reference to fig. 9 to 14. The stirring shaft 1 has a cylindrical base body 2 with a longitudinal axis L, wherein stirring elements 3, in particular cams 4, are formed on the outer side of the cylindrical base body 2. The outer side of the cam 4 and the outer side of the cylindrical base body 2 not covered by the cam 4 together form an outer side 5 of the stirring shaft 1. The stirring elements 3 are formed on the outer side of the cylindrical basic body 2 in a plurality of rows, in particular each in an aligned arrangement, wherein the rows are arranged and/or formed parallel to the longitudinal axis L of the stirring shaft 1.

According to the invention, it is provided that the stirring shaft 1 is of one-piece design and is made of a ceramic material in particular. Particularly preferably, the stirring shaft 1 is produced from a ceramic material by a single process step. In particular, a 3D printing method is preferably used for this, since with this method a cavity can also be produced within the stirring shaft 1 in a single process step.

The ceramic material can be, for example, silicon carbide (SiC), in particular sintered silicon carbide (SSiC), silicon carbide with free silicon (SiSiC), silicon nitride, zirconium dioxide or mixed ceramics. Silicon carbide ceramics have high wear resistance, low thermal shock sensitivity, low thermal expansion, high thermal conductivity, good acid and alkali resistance and are lightweight and retain their advantageous properties at temperatures above 1400 ℃. In addition, silicon carbide is toxicologically harmless and therefore can be used in the food industry. Although the hardness of silicon nitride is reduced compared to silicon carbide. However, by the sintering process, columnar recrystallization of the β -silicon nitride crystal can be achieved, which results in an increase in the fracture toughness of the material. The combination of high fracture toughness and small defect size makes silicon nitride one of the highest strength engineering ceramic materials. Silicon nitride ceramics are particularly useful for thermal shock stress components due to a combination of high strength, low coefficient of thermal expansion, and relatively low modulus of elasticity. Zirconium dioxide has a very high resistance to crack propagation compared to other ceramic materials. In addition, zirconia ceramics have a very high thermal expansion, and so one would prefer to choose when making a connection between the ceramic and the steel.

In the technical side view of the stirring axle 1 according to fig. 2 and in the sectional view according to fig. 6, a cooling channel 6 can be seen, which is formed within the one-piece stirring axle 1. Preferably, the cooling channel extends at least partially parallel to the longitudinal axis L of the stirring shaft 1. It is particularly preferably provided that the passages 6 extend in a meandering manner between the end regions of the stirring shaft 1 and in particular each turn at the end regions, wherein the regions between the reversals can each be arranged substantially parallel to one another. Fig. 2 shows, for example, three parallel sections 61, 62, 63 of the cooling channel 6, which are configured parallel to one another and are also arranged parallel to the longitudinal axis L of the mixing shaft. Two deflecting regions 67, 68 are formed between the three parallel regions 61, 62, 63 in the end region of the mixing shaft 1.

Coolant flowing through the first parallel section 61 in the first flow direction SR1 is diverted in the first diverting region 67 into the second parallel section 62 and flows through the second parallel section in a second flow direction SR2, which extends counter to the first flow direction SR 1. The coolant then reverses in the second reversing region 68 into the third parallel portion 63 and flows through it again in the first flow direction SR 1.

The stirring axle 1 shown in fig. 3 shows, in a sectional view along the section line a-a according to fig. 2, that the cooling channel 6 formed within the stirring axle 1 has six parallel sections 61, 62, 63, 64, 65 and 66, wherein the first parallel section 61 and the second parallel section 62 are connected via a first diverting section 67, the second parallel section 62 and the third parallel section 63 are connected via a second diverting section 68, the third parallel section 63 and the fourth parallel section 64 are connected via a third diverting section (not shown), the fourth parallel section 64 and the fifth parallel section 65 are connected via a fourth diverting section (not shown), and the fifth parallel section 65 and the sixth parallel section 66 are connected via a fifth diverting section 69 (see fig. 6). In particular, it can be provided that the coolant enters the stirring shaft 1 via the first parallel section 61 of the cooling channel 6 and is discharged from the stirring shaft 1 via the sixth parallel section 66 of the cooling channel 6.

The stirring shaft 1 has three subsections, in particular a first subsection I at the end, a second subsection II in the middle and a third subsection III at the end. The stirring shaft 1 can be connected at its first end subsection I to a drive shaft 70 of a stirred ball mill (not shown). For this purpose, a corrugated receptacle 7 is formed in the first end subsection I, for example. The stirring shaft 1 is at least partially designed as a hollow shaft, in particular the second and third partial sections II, III and optionally the first partial section I each have an inner space region. In particular, the middle second subsection II has a hollow first interior space, i.e. interior space region 12, and the third subsection III has a hollow second interior space, i.e. interior space region 13. It preferably likewise has a cylindrical shape, the longitudinal axes of which coincide in each case with the longitudinal axis L of the stirring shaft 1. Furthermore, it is provided that the third subsection III is open at the end and exhibits, in particular in the region of the opening, a further enlarged hollow interior. A wear member or the like may be disposed within the hollow interior cavity as described below in connection with fig. 9-14.

Furthermore, it can be provided that a through-opening 15 is formed in the intermediate second subsection II between the hollow interior region 12 and the outer lateral surface 5 of the stirring shaft 1, the function of which is likewise explained below in conjunction with fig. 9 to 14. The middle second subsection II is therefore also referred to as an open subsection, while the first subsection I and the third subsection III are each shown as a closed subsection. The through-openings 15 extend in particular parallel to the longitudinal axis L of the mixing shaft, preferably in each case between a plurality of rows with mixing elements 3 as described in particular in connection with fig. 1.

As is apparent, for example, from fig. 6, at least one cooling duct 6 preferably extends through all three subsections I, II and III of stirring shaft 1, wherein the deflecting regions 67, 68, 69 are formed in the end subsections I and III, respectively. In particular, the cooling channel 6 is designed to be meandering, as will be described in more detail below.

Fig. 4 shows a longitudinal section through the stirring shaft 1, in particular a section through the stirring shaft 1 along section line B-B according to fig. 3. Fig. 3 shows in particular a cross section of the stirring shaft 1 in the second subsection II, which in particular passes through the stirring element 3. The through-opening 15 between the first hollow interior region 12 and the outer side 5 of the mixing shaft 1 is clearly visible here. Fig. 4 shows that the cooling channel 6 is in particular designed as a through-opening 15 which runs parallel to the longitudinal axis L and parallel to the axis, wherein the parallel sections 61, 62, 63, 64, 65, 66 of the cooling channel 6 each run adjacent to a row of stirring elements 3.

Figure 7 shows a side view of the wear protection sleeve 30 and figure 8 shows a perspective view of the wear protection sleeve 30. The arrangement of the wear protection sleeve 30 inside the stirred ball mill 50 and its function are described in particular below in connection with fig. 10, 12 and 13.

The wear-resistant protective sleeve 30 is at least partially cylindrical, in particular the wear-resistant protective sleeve 30 having a hollow cylinder 33 as a base body 32, on the outside of which a projection 34 is preferably formed, in particular in the form of a cam 35, which is described in more detail below. The hollow cylinder has an outer diameter d30 which is smaller than the smallest inner diameter dIII of the third interior region III of the stirring shaft 1 (see fig. 2). A fastening region, for example a flange 36, can be provided on the end region of the wear-resistant protective sleeve 30 in order to position and fasten the wear-resistant protective sleeve 30 in or on the agitator ball mill 50, in particular to fasten the wear-resistant protective sleeve 30 on the grinding container base 59, in particular in a suitable receptacle of the grinding container base 59, see fig. 10 and 12.

The wear protection sleeve 30 is preferably likewise of one piece and in particular made of a ceramic material and can be made of one of the aforementioned ceramic materials similarly to the stirring shaft 50, for example in a 3D printing method.

Furthermore, it can be provided that the wear protection casing 30 comprises at least one cooling channel, which is likewise designed, for example, to be meandering and thus to form a large cooling surface (not shown). The configuration of the at least one cooling channel of the wear protection sleeve may correspond to the configuration of the cooling channel 6 of the stirring axle 1. The lines for conveying and removing the coolant can be formed, for example, by the grinding container bottom (59, see fig. 10, 12).

The wear protection sleeve 30 can preferably be used in an agitator ball mill 50 shown in fig. 9 to 14 with an agitator shaft 1 according to fig. 1 to 6. The wear protection sleeve 30 may also be used in conjunction with an agitator shaft made according to conventional methods.

Fig. 9 to 14 show different views and schematic diagrams of a stirred ball mill 50 with a stirring shaft 1 according to the invention, in particular fig. 9 shows a front view of the stirred ball mill 50, fig. 10 shows a sectional view of the stirred ball mill along a sectional line a-a according to fig. 9, and fig. 11 shows a sectional view of the stirred ball mill 50 along a sectional line B-B according to fig. 10.

The agitator ball mill 50 comprises a cylindrical milling container 51 extending along a horizontal axis L50, the milling container having an inner side 52. The milling container 51 can be made of metal or of a ceramic material, similar to the stirring shaft 1. It can furthermore be provided that the grinding container is designed to be coolable and comprises, for example, an outer cylinder 53 and an inner cylinder 54, between which a cooling space 55 is designed, into which a coolant K can be introduced via suitable coolant inlets 56 and cooling outlets 57. Milling container 51 further includes a milling container top cover 58 and a milling container bottom 59.

A stirring shaft 1 having a longitudinal axis L is arranged horizontally within the milling container 1. The longitudinal axis L of the stirring shaft 1 is at the same time the axis of rotation thereof and is also arranged coincident with the horizontal axis L50 of the milling container 51. The stirring shaft 1 corresponds to the stirring shaft 1 described in fig. 1 to 6, so reference can be made to the description of its features.

A drive shaft 70 passes through grinding container top 58 and is connected to a drive device, such as an electric motor or the like (not shown). The drive shaft 70 is connected to the stirring shaft 1 in a rotationally fixed manner, in particular the end of the drive shaft 70 projecting into the milling container 51 engages in a shaft receptacle 7 in the first subsection I of the stirring shaft 1. Furthermore, the milling container head 58 comprises a milled-material inlet 71, via which the milled material M is filled into the agitator ball mill 50. In the milling container bottom 59, a product outlet 72 is provided, through which the ground product P leaves the agitator ball mill 50.

An annular grinding gap MS is formed between the inner side 52 of the grinding container 51 and the outer side 5 of the stirring shaft, in particular in the region of the stirring elements 3. In which the grinding material/grinding aid body mixture is located during the operation of the agitator ball mill 50. The grinding material M in the grinding gap MS is stressed by the rotational drive of the stirring shaft 1 and the grinding aids (not shown) such that the grinding material is comminuted, for example by the grinding material particles impacting one another, by shear forces or the like. In order to intensify the comminution action, it can be provided that projections, such as cams, rods or the like, can also be arranged on the inner side 52 of the grinding container 51, which on the one hand bring about additional mixing of the grinding material/grinding aid mixture and on the other hand, for example, increase the number of collision processes in the grinding gap MS, thus increasing the comminution action of the agitator ball mill 50.

Furthermore, it is provided that the product outlet 72 is formed in a so-called receiving part 75 which extends through a central opening in the grinding container base 59. The receiving part 75 can likewise have a cooling channel 76, through which a coolant K is conducted for cooling the product P. The receiving part 75 extends in particular axially in the interior of the mixing shaft 1 in the direction of the milled material inlet 71 and is partially surrounded by the wear-resistant protective sleeve 30 in the region of the product outlet 72. At the end region of the containing part 75, which is arranged axially opposite the product outlet 72, a screening device 40, which will be described in detail below, is preferably arranged for intercepting the milling aids in the interior of the agitator ball mill during the removal of the product P.

The cross section of the agitator ball mill 50 shown in fig. 11 is in particular compared to the cross section of the agitator shaft 1 shown in fig. 3 in the region of the central second subsection II. The detail enlargement shows in particular an alternative embodiment of the cooling channel 6, which does not have a circular cross section, but rather an optimized enlarged cross section.

The shape of the cam 4 should be described in detail in this context. As already mentioned, the stirring shaft 1 is produced in one piece, in particular when the stirring shaft 1 is produced, the stirring elements 3 are formed directly together and do not need to be fixed subsequently. The stirring element 3 is in particular designed as a cam 4 which projects from the cylindrically designed base body 2 of the stirring shaft 1. The connection surface 20 of the cam 4, which is formed on the base body 2 of the mixing shaft 1, is formed relatively large, in particular relatively large compared to the radial height h of the cam 4. The shape of the cam 4 can have any geometric shape in axial section and in radial direction, for example trapezoidal, with rounded corners, with chamfered edges, etc. The connecting surface 20 corresponds in particular to the base surface of each cam 4 and is the surface of each cam 4 that is in contact with the outer lateral surface of the mixing shaft 1.

Since in the exemplary embodiment shown the

cooling channels

6, 6 are formed adjacent to the cams 4, heat can advantageously be conducted from the milled material/milling aid mixture via the large connections 20 of the cams 4 into the coolant within the cooling channels 6, since the large connection surfaces 20 conduct the heat away more efficiently. Furthermore, the susceptibility of the cam 4 to fracture or fracture, which occurs in particular in ceramic materials, is significantly reduced by the shape. The one-piece embodiment of the stirring shaft 1 promotes stability and thermal conductivity, since potential fracture points and thermal conductivity barriers are eliminated.

For good stability of the cams 4 and for achieving a uniformly good grinding effect, it is advantageous if each cam 4 has a connecting surface 20 with the base body 2 of the mixing shaft 1 and an end-side flow surface 21 (see also fig. 1), wherein the ratio of the projection of the end-side flow surface 21 onto a plane perpendicular to the base body 2 of the mixing shaft 1 to the size of the connecting surface 20 is less than 1.

For example, it is advantageous if the connection surface 20 of each cam 4 to the stirring axle 1 has a maximum width and the ratio of the height of each cam 4 perpendicular to the stirring axle 1 to this maximum width is greater than 0.2. Furthermore, the connection surface 20 of each cam 4 to the mixing axis 1 has a maximum length, wherein the ratio of the height to the maximum length of each cam 4 is preferably less than 1. According to a further embodiment, it is advantageous if the connection surface 20 of each cam 4 to the mixing axis 1 has a maximum length and a maximum width, wherein the ratio of the maximum width to the maximum length is less than 1.

Fig. 18A to 18E are also referred to in this regard. Fig. 18A to 18E each show a further embodiment of the stirring shaft 1. They each show a cross section of the outer side 5, in which, analogously to fig. 3, through-holes, cooling channels, etc. are omitted. In particular, in different embodiments, the arrangement and configuration of the stirring element 3 or of the cam 4 on the outer lateral surface 5 are different in each case. For example, the slope of the front side or the surge surface 21 in the direction of rotation D and the slope of the rear side in the direction of rotation D are configured to be significantly different.

In this case, the angle of inclination of the end-side inflow surface 21 with respect to a plane perpendicular to the inner side of the milling container 59 and/or to the cylindrical outer side of the stirring shaft 1 can lie in the range from-45 ° to 85 ° in the region of the plane. An angle of 0 ° corresponds here to the inflow surface 21 lying in a plane perpendicular to the inside of the grinding container 59 (see fig. 18C), while an angle with a minus sign indicates a lateral inflow surface 21, i.e. the inflow surface 21 is inclined such that it appears to cover a certain area of the connecting surface 20 (see in particular fig. 18D, 18E). The inclination angle with a plus sign therefore indicates an oppositely inclined end-side current surface 21, i.e. the end of the current surface 21 lying on the substrate 2 is flowed through first (see in particular fig. 18A, 18B, 18E).

In principle, it is advantageous to provide the stirring shaft 1 with a plurality of cams 4 in order to promote the desired interaction of the milled material/milling aid mixture. For this purpose, the stirring shaft 1 can also have regions without cams, or can have more cams 4 in some regions and fewer cams 4 in other regions. Furthermore, it is not necessary that all cams 4 are identically constructed, but they can be arranged in different regions in different shapes and sizes.

As can be seen in particular from fig. 1, it can be advantageous if a plurality of cams 4 are arranged in succession in a row in the circumferential direction of the base body 2 of the mixing shaft 1 along the circumferential line of the base body 2 of the mixing shaft 1. For example, the distance between the cams 4 of a row successive in the circumferential direction can be equal to or greater than the maximum length of the cams 4 in the circumferential direction.

If a plurality of cams 4 are arranged in each case in succession in rows along a plurality of circumferential lines spaced apart from one another in the axial direction, the axial spacing between two respective axially adjacent cam rows is advantageously greater than or equal to 1.1 times the maximum width of the cams 4. If cams 4 are formed on base body 2 of mixing shaft 1 at a distance from one another in the axial direction, cams 4 can then be arranged axially aligned or offset from one another.

According to fig. 12, which shows a sectional view of the agitator ball mill 50 along the sectional line C-C of fig. 11, the path of the grinding material/grinding aid mixture G inside the agitator ball mill 50 is described in particular. The milled material M is filled into the inner cavity of the milling container 51 via the milled material inlet 71. The grinding container has been partially filled with grinding aid bodies, for example the inner chamber of the grinding container has been filled approximately 80% with grinding aid bodies. As a result of the rotation of the stirring shaft 1, the grinding material M and the grinding aid bodies (not shown) are mixed to form a grinding material/grinding aid body mixture G which flows along the stirring shaft 1 between the inner side 52 of the grinding container 51 and the outer side 5 of the stirring shaft 1 in the first conveying direction FR1 in the direction of the grinding container bottom 59. A distance is formed between the open end of the third subsection III of the stirring shaft 1 and the grinding container base 59, in which distance the flow of the grinding material/grinding aid mixture G is reversed, so that the grinding material/grinding aid mixture now flows through the hollow second interior region 13 of the third subsection III of the stirring shaft 1 in a second conveying direction FR2 opposite the first conveying direction FR 1.

Within the second interior region 13 is arranged an anti-wear protective sheath 30 (see also fig. 10). Such an anti-wear protective casing 30 has been described in connection with fig. 7 and 8, the description of which refers to fig. 7 and 8. A grinding gap is again formed between the inner side of the stirring shaft 50 of the third interior region III and the outer side of the wear-resistant protective sleeve 30, in which the grinding material/grinding aid mixture G is guided in the conveying direction FR2 in the direction of the first hollow interior region 12 of the central second subsection II. The grinding gap is particularly small between the cam 35 of the wear protection sleeve 30 and the inner side of the stirring shaft 50 of the third inner cavity region III. The cams 35 serve in particular as scrapers to prevent the grinding material and/or grinding aids from adhering to the inner side of the stirring shaft 1. Instead, it is ensured by the cam 35 that the grinding material/grinding aid mixture G remains flowing and is fed in the conveying direction FR2 into the through-opening 15 in the second partial section, where the grinding aid flows back in the direction of the grinding chamber or grinding gap MS formed between the outer side of the stirring shaft 1 and the inner side 52 of the grinding container 51.

Within the first hollow interior region 12, a screening device 40, a classifying rotor 41 or other suitable devices are arranged, which intercept the grinding aids of the grinding material/grinding aid mixture G, while the fully ground grinding material passes through as finished product P and can be removed from the agitator ball mill 50 via a product outlet 72. The milling aids intercepted by the sifting device 40, the classifying rotor 41, etc., and, if appropriate, the milled material M that has not yet been ground to a sufficient degree, are returned via the through-opening 15 in the middle second subsection II of the stirring shaft 1 into the milling gap MS between the milling container 51 and the stirring shaft 1 and are moved back in the conveying direction FR 1.

Fig. 13 shows a sectional view of the agitator ball mill 50 along section line D-D according to fig. 12, wherein the arrangement of the wear-resistant protective sleeve 30 within the second hollow interior region 13 of the third subsection III of the agitator shaft 1 can be seen.

Fig. 14 shows a cross-sectional view of the stirred ball mill 50 according to fig. 9 with a meandering cooling channel 6 according to section line E-E. The course of the first parallel portion 61 of the cooling channel 6 and the course of the sixth parallel portion 66 of the cooling channel 6 are visible in particular here. The coolant K is supplied via the coolant inlet 56 and flows through the first parallel portion 61 of the cooling channel 6 in the first flow direction SR 1. As described in connection with fig. 6, the coolant 6 is diverted several times and finally flows through the sixth parallel section 66 of the cooling channel 6 in the second flow direction SR2, which is opposite to the first flow direction SR1, before the coolant is discharged from the stirring shaft 1 via the cooling outlet 57.

Fig. 15 shows a perspective view of a further embodiment of a stirring shaft 1 according to the invention, constructed in one piece. In this embodiment, the schematic illustration of the stirring element 3, in particular the cam 4, and the more exact design of the three partial sections I, II and III are partially omitted. However, the features described in connection with fig. 1 also apply to the embodiments described in detail below, in particular with regard to the configuration of the at least one cooling channel 6.

The cooling channels 6 shown here are so-called convective cooling. On the one hand, the cooling duct 6 has two parallel portions 81, 82 on a first radius R1 extending between the longitudinal axis L of the mixing shaft 1 and the outer lateral surface 5. In particular, it is provided that the coolant is introduced into the first parallel section 81 and flows through the first parallel section in a first flow direction SR1 from the first subsection I in the direction of the third subsection III, wherein the first flow direction SR1 preferably corresponds to the first conveying direction FR1 for the grinding material/grinding aid mixture according to fig. 9 to 14. In the case of convection cooling, it is provided in particular that the coolant K flows through two parallel portions 81 and 82, 83 and 84, 85 and 86, 87 and 88 in succession, which lie on a common radius R, R1, R2, R3, R4 of the stirring shaft 1. In particular, first of all, the parallel portions 81, 83, 85, 87, which extend relatively close to the longitudinal axis L, are flowed through by the coolant K. The coolant K then reverses in the end region of the third subsection III in the reversing region 95 into the parallel sections 82, 84, 86 or 88 arranged on the same radius R1, R2 or R3, respectively, and flows through the parallel sections in a second flow direction SR2 opposite the first flow direction SR 1. A deflecting region 91 is formed in the free end region of the first subsection I, which deflects the coolant K from the second parallel section 82 on the first radius R2 into the parallel section 83 on the second radius R2, which is formed closer to the longitudinal axis L of the mixing shaft. At this point, the coolant again flows through the third parallel portion 83 in the first flow direction SR1 and can then be diverted via a further diverting region 95 in the third subsection III into a fourth parallel portion 84, which is formed on the same second radius R2 and is spaced further from the longitudinal axis L, and so on. Finally, the coolant flows in the second flow direction SR2 through the last parallel portion 88 formed on the fourth radius R4 and is discharged from the stirring shaft 1. In the case of the convection cooling described here, two parallel sections 81 and 82, 83 and 84 of the cooling duct 6, which extend in parallel, are located on the same radius R of the stirring shaft 1, through which the coolant K flows in opposite flow directions SR1, SR 2. In particular, the coolant K is guided in each case close to the longitudinal axis L of the stirring shaft 1 from the grinding material inlet side to the product outlet side. The return flow of the coolant K from the product outlet side to the milled material inlet side takes place within the stirring shaft 1 in the region adjacent to the outer side of the stirring shaft 1.

Preferably, it can be provided that the coolant K does not flow through the parallel portions 81 to 88 in succession, but rather that new coolant K flows into each of the parallel portions 81, 83, 85, 87 which are formed closer to the longitudinal axis L and flows out of the parallel portions 82, 84, 86, 88 which are formed closer to the outer side of the mixing shaft 1. The commutation region 91 is preferably designed here as an annular gap 92. This achieves that the most recent and therefore the coldest coolant K is initially introduced into the hottest region of the milled material of the agitator ball mill. This is in particular the region close to the product outlet after the milled material has flowed through the agitator ball mill from the milled material inlet side. The cooling process can be further optimized by means of this convective cooling.

Fig. 16 shows a longitudinal section through a stirred ball mill with a further embodiment of a stirring shaft 1 with cooling channels 6 configured for convection cooling, and fig. 17 shows a cross section through section line a-a of the stirred ball mill with a stirring shaft according to fig. 16. In this case, it is provided that the coolant is fed in a first flow direction SR1 via a coolant feed line 93 within the drive shaft 70 of the mixing shaft 1 and flows through the first parallel portion 81 of the cooling channel 6 in a flow direction SR1 through the coolant feed line. The first flow direction SR1 preferably corresponds to the first conveying direction FR1 for the milled material/milling aid mixture according to fig. 9 to 14. The first parallel sections 81 are also referred to as inner flow channels 94.

In the end regions of the third subsection III, a respective deflecting region 95 is formed, which connects the inner flow channel 94 to the second parallel section 82 of the cooling channel 6. The second parallel section 82 is also referred to as an outer flow channel 96. In particular, the coolant K is diverted in the diverting region 95 and now flows through the outer flow duct 96 in a second flow direction SR2 opposite the first flow direction SR1 and then leaves the stirring axle 1 via a coolant discharge line 97 within the drive shaft 70. For this purpose, an inner flow channel 94 and an outer flow channel 96 are arranged on the radius R of the stirring axle 1, wherein the inner flow channel 94 is arranged closer to the longitudinal axis L of the stirring axle 1 than the outer flow channel 96.

In this type of convection cooling, two parallel sections 81 and 82, each having a cooling channel 6, which extend in parallel, are located on a common radius R of the stirring shaft 1 and are flowed through by the coolant K in opposite flow directions SR1, SR 2. In this case, it is particularly advantageous if the coolant K is removed again after it has flowed through the mixing shaft 1 once in the first flow direction SR1 and once in the second flow direction SR 2. All parallel sections 82 are therefore cooled to the same extent, whereas in the exemplary embodiment according to fig. 15 the cooling in the last parallel section 88 is significantly reduced compared to the cooling in the second parallel section 82. The cooling of the stirring axle 1 according to fig. 16 is therefore further optimized with respect to the cooling of the first embodiment of the stirring axle 1 according to fig. 15.

The conveying of the grinding stock M, the flow guidance of the grinding stock/grinding aid mixture G inside the agitator ball mill 50 and the removal of the product P are also shown in fig. 16, see also the description of fig. 12.

Furthermore, embodiments are conceivable in which an annular gap is formed in the first subregion I of the mixing shaft 1 for the coolant supply. Starting from this annular gap, a plurality of cooling channels extend in the first flow direction SR1 in the direction of the third partial region III. In this case, a plurality of deflecting channels are formed, which return in the second flow direction SR2 in the counter-flow to the first flow direction SR1 and in the counter-flow to the conveying direction FR of the grinding stock/grinding aid mixture G, in particular back to a further annular gap, in which the "used" cooling medium is collected and discharged. In particular, it is achieved that each corrugation section is cooled by a new coolant.

The embodiments, examples and variants of the preceding paragraphs, the claims or the following description and drawings and their different views or the respective individual features can be applied independently of one another or in any combination. Features described in connection with one embodiment may be used with all embodiments unless the feature is incompatible.

In referring generally to the "schematic" diagrams and views in relation to the drawings, this does not mean that the illustration of the drawings and the description thereof are not important to the disclosure of the present invention. The skilled person will fully appreciate that from the figures shown schematically and abstractly, sufficient information can be obtained to enable him to easily understand the invention without affecting the comprehension of the skilled person in any way, for example due to parts and/or components of the apparatus or other elements drawn which are drawn and may not be to scale to a precise scale. The figures thus enable a skilled person to derive as a reader the inventive idea, which is generically and/or abstractly stated in the claims and in the general part of the description, on the basis of the specifically mentioned implementations of the method according to the invention and the specifically mentioned functions of the device according to the invention.

The invention has been described with reference to the preferred embodiments. It will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects.

List of reference numerals

1 stirring shaft

2 cylindrical base body

3 stirring element

4 cam

5 lateral surface

6. 6 cooling channel

7-shaft accommodating part

12 first lumen region

13 second lumen region

15 through hole

20 connecting surface

21 end side surface of inrush current

30 anti-wear protective sleeve

32 cylindrical base body

33 hollow cylinder

34 projection

35 cam

36 flange

40 screening device

41 classifying rotor

50 stirring ball mill

51 milling container

52 medial side

53 outer cylinder

54 inner cylinder

55 cooling space

56 coolant inlet

57 coolant outlet

58 grind container top cap

59 grinding container bottom

61 (first) parallel sections of a cooling channel

62 (second) parallel section of cooling channel

63 (third) parallel section of Cooling channel

64 (fourth) parallel section of cooling channel

65 (fifth) parallel section of cooling channel

66 (sixth) parallel section of cooling channel

67 (first) reversing region of cooling channel

68 (second) reversing region of cooling channel

69 (fifth) reversing region of cooling channel

70 drive shaft

71 ground material inlet

72 product outlet

75 accommodating member

76 cooling channel

81 (first) parallel section

82 (second) parallel section

83 (third) parallel section

84 (fourth) parallel section

85 (fifth) parallel section

86 (sixth) parallel section

87 (seventh) parallel section

88 (eighth/last) parallel section

91 commutation region

92 annular gap

93 coolant supply line

94 internal flow passages

95 commutation region

96 external flow channel

97 coolant discharge line

d30 outer diameter of wear protection sleeve

Internal diameter of third subsection dIII

D direction of rotation

FR1 first conveying direction

FR2 second conveying direction

G grinding material/grinding auxiliary body mixture

height of h cam

I first sub-section at the end

II intermediate second subsection

III third sub-section at the end

K coolant

Longitudinal axis of L stirring shaft

Axis of milling container of L50 agitated ball mill

M milled Material

MS grinding gap

P product

Radius R

R1 first radius

R2 second radius

R3 third radius

SR1 first flow direction

SR2 second flow direction.

Claims

1. Stirring shaft (1) for a stirring ball mill (50), wherein the stirring shaft (1) has a longitudinal axis (L) and an outer side (5) equipped with stirring elements (3), wherein the stirring shaft (1) is formed in one piece with the stirring elements (3) and is made of a ceramic material, wherein the stirring shaft (1) has at least one cooling channel (6), wherein the at least one cooling channel (6) is formed in a meandering manner.

2. The mixing shaft (1) according to claim 1, characterised in that the at least one cooling channel extends at least partially parallel to a longitudinal axis (L) of the mixing shaft (1).

3. The mixing shaft (1) according to claim 1, characterised in that the at least one cooling channel (6) extends in at least two regions in each case parallel to the longitudinal axis (L) of the mixing shaft (1), wherein a reversal region is formed between two parallel-extending regions.

4. Stirring shaft (1) according to claim 3, characterised in that the coolant flows in opposite flow directions through at least two regions which are connected to one another via a reversal region.

5. The mixing shaft (1) according to claim 2, characterised in that the at least one cooling channel (6) extends in at least two regions in each case parallel to the longitudinal axis (L) of the mixing shaft (1), wherein a reversal region is formed between two parallel-extending regions.

6. Stirring shaft (1) according to claim 5, characterised in that the coolant flows in opposite flow directions through at least two regions which are connected to one another via a reversal region.

7. The stirring axle (1) according to claim 3, characterized in that coolant flows through every two parallel-running regions in opposite flow directions, which are arranged on a common radius (R1, R2 or R3) of the stirring axle (1).

8. Stirring shaft (1) according to claim 4, characterized in that coolant flows through every two parallel-running regions in opposite flow directions, which are arranged on a common radius (R1, R2 or R3) of the stirring shaft (1).

9. Stirring shaft (1) according to claim 5, characterised in that coolant flows through every two parallel-running regions in opposite flow directions, which are arranged on a common radius (R1, R2 or R3) of the stirring shaft (1).

10. Stirring shaft (1) according to claim 6, characterised in that coolant flows through every two parallel-running regions in opposite flow directions, which are arranged on a common radius (R1, R2 or R3) of the stirring shaft (1).

11. The mixing shaft (1) according to one of claims 1 to 10, characterised in that the mixing shaft (1) has a first endmost partial section (I) on which the mixing shaft (1) can be arranged on a drive shaft (70), wherein the mixing shaft (1) also has a second intermediate partial section (II) and a third endmost partial section (III).

12. The stirring shaft (1) according to any one of claims 7 to 10, wherein said at least one cooling channel (6) extends within a first endmost subsection (I) and at least partially within an intermediate second subsection (II).

13. The stirring shaft (1) according to claim 12, wherein said at least one cooling channel (6) extends through all three subsections.

14. The mixing shaft (1) according to claim 11, wherein the intermediate second subsection (II) has a first hollow interior (12).

15. The mixing shaft (1) according to claim 12, wherein the intermediate second subsection (II) has a first hollow interior (12).

16. The mixing shaft (1) according to claim 14 or 15, characterized in that the first hollow interior (12) is cylindrically configured and has a longitudinal axis which is configured to coincide with a longitudinal axis (L) of the mixing shaft (1).

17. The mixing shaft (1) according to claim 11, wherein the third terminal subsection (III) has a second hollow interior (13).

18. The mixing shaft (1) according to claim 12, wherein the third terminal subsection (III) has a second hollow interior (13).

19. The mixing shaft (1) according to claim 17 or 18, characterised in that the second hollow interior (13) is of cylindrical configuration and has a longitudinal axis which is configured to coincide with a longitudinal axis (L) of the mixing shaft (1).

20. Stirring axle (1) according to claim 14 or 15, characterized in that a through-opening (15) is formed between the first hollow interior (12) of the intermediate second subsection (II) and the outer lateral surface (5) of the stirring axle (1) in the region of the intermediate second subsection (II).

21. The mixing shaft (1) according to claim 16, characterised in that a through-opening (15) is formed between the first hollow interior (12) of the intermediate second subsection (II) and the outer lateral surface (5) of the mixing shaft (1) in the region of the intermediate second subsection (II).

22. The mixing shaft (1) according to one of the claims 1 to 10, characterised in that the mixing elements (3) are configured as cams (4) which project from a base body (2) of the mixing shaft (1), wherein the connection faces of the configuration of the cams (4) on the base body (2) are relatively large.

23. The mixing shaft (1) according to claim 22, characterised in that each cam (4) has a connection surface with the base body of the mixing shaft (1) and a preceding side, wherein the ratio of the projection of the preceding side onto a plane perpendicular to the base body of the mixing shaft to the size of the connection surface is less than 1.

24. The stirring shaft (1) according to any one of claims 1 to 10, characterised in that the stirring shaft (1) with the stirring elements (3) can be made in a 3D printing method.

25. A stirred ball mill (50) having a milling container (51) extending along a horizontal or vertical axis (L50) and a stirring shaft (1) rotatable within the milling container (51) about a horizontal or vertical axis (L50), the milling container has an inner side (52), the stirring shaft has an outer side (5), wherein a stirring element (3) is formed on the outer lateral surface (5), wherein, a grinding gap (MS) is formed between the stirring elements (3) of the stirring shaft (1) and the inner side (52) of the grinding container (51), wherein the stirring shaft (1) is formed in one piece with the stirring element (3) and is made of a ceramic material, and the stirring ball mill (50) has a stirring shaft (1) according to one of claims 1 to 24.

26. Stirred ball mill (50) according to claim 25, comprising an anti-wear protective sleeve (30) which can be arranged in the interior of the stirring shaft (1), which is composed of a ceramic material and is constructed in one piece.

27. Method for manufacturing a stirring shaft (1) of any one of claims 1 to 24 of a stirring ball mill (50), wherein the stirring shaft (1) is made in one piece of a ceramic material.

28. Method according to claim 27, characterized in that the stirring axle (1) with the stirring elements (3) is made by means of 3D printing.