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

Abstract

Stirring shaft (1) for a stirred ball mill (50), wherein the stirring shaft (1) has a longitudinal axis (L) and an outer shell surface (5) equipped with stirring elements (3), wherein the stirring shaft (1) is formed integrally with the stirring elements (3) and is made of a ceramic material, wherein the stirring shaft (1) has at least one cooling channel (6) which preferably extends at least partially parallel to the longitudinal axis (L) of the stirring shaft (1), wherein the at least one cooling channel (6) extends in at least two regions parallel to the longitudinal axis (L) of the stirring shaft (1), wherein a deflection region (67) is formed between the two parallel regions (61, 62), in particular wherein a coolant flows through the at least two regions (61, 62) connected to each other via a deflection region (67) in opposite flow directions (SR1, SR2).

Description

[0001] The present invention relates to a stirring shaft for a stirred ball mill, a stirred ball mill and a method for manufacturing a stirring shaft for a stirred ball mill according to the features of the independent claims. State of the art

[0002] The invention relates to a stirred ball mill, in particular an agitator for a stirred ball mill. A stirred ball mill is a device for coarse, fine, and ultrafine grinding or homogenization of materials. A stirred ball mill consists of a vertically or horizontally arranged, usually approximately cylindrical grinding chamber, which is 70% to 90% filled with grinding media. In stirred ball mills, the grinding chamber is generally stationary. Many conventionally known mills are filled through a central opening in one of the end walls. Alternatively, filling can also be done directly via the grinding cylinder. During the grinding process, the product to be ground flows continuously from a product inlet axially through the grinding chamber to a product outlet. The suspended solids are thereby comminuted or dispersed by impact and shear forces between the grinding media.In an outlet area, the grinding aids are separated from the product stream. The discharge method depends on the design and is achieved, for example, through a sieve at the end of the mill.

[0003] The agitator typically consists of an agitator shaft that rotates agitator elements in the form of discs or radially projecting pins, primarily to deagglomerate and break down solids of the material being ground, which are dispersed in the liquid. The agitator shaft is usually driven by a motor. Disc agitators with multiple grinding discs arranged on a single shaft are particularly suitable as agitator elements. The grinding discs are usually circular and may be equipped with through-holes. These through-holes ensure the proper flow of the product.

[0004] Between the inside of the grinding cylinder and the agitator, an annular grinding gap is formed, in which the material to be ground is located during operation of the stirred ball mill. The agitator is driven by a rotating mechanism and thus impinges on the material within the grinding gap, causing it to be ground. This process is supported by both the grinding media and the agitator's stirring elements. In particular, the material and the grinding media are intensively agitated by a stirring shaft. During this process, the solid particles of the material are broken down by impact, pressure, shear, and friction.

[0005] The stirring shafts or agitators preferably consist of an abrasion-resistant material, in particular a metal or a ceramic material; for example, WO 2000 / 054884 A describes a stirred ball mill in which the agitator, in particular the disc-shaped stirring elements, consists of a ceramic material.

[0006] Utility model DE 20 2017 104 764 U1 describes a stirring shaft with cams.

[0007] German patent DE 2626757 A1 discloses a stirring propeller designed such that only relatively simple and inexpensive parts are subject to wear and tear and that these parts are easily replaceable. Where economically feasible, these simple parts are made of a particularly abrasion-resistant material, such as ceramic.

[0008] Many processes, whether chemical, mechanical, or otherwise, generate process heat, which can negatively impact the process itself or the raw materials used. This is because, for example, the substances involved in the process are temperature-sensitive, or the temperature change affects the process rate, thus complicating orderly process control. For this reason, it is common practice to stabilize a process by, for example, dissipating the generated process heat using suitable cooling devices or methods.Processes taking place in containers are usually temperature-controlled via the container wall, for example by means of cooling or hot water pipes running along the wall, or by placing another outer container radially spaced from the first container around the first container, so that a cavity forms between the two containers through which a fluid flow, which can be a hot water flow or a coolant flow, can be guided to transport the process heat.

[0009] Heat is also generated during the grinding process. Depending on the product, this heat must be dissipated or its formation prevented. This is particularly problematic with stirred ball mills with a large grinding volume or when a higher power input is desired. To cool the mill during the grinding process, for example, the grinding cylinder can be designed to be cooled. For instance, German patent application DE 3614721 A1 describes the equipping of the grinding container with a cooling jacket as a known prior art. This document further discloses that the agitator rotor can also be provided with at least one cooling channel around its circumference. A grinding container with a cooling jacket is also shown in patent application WO 2007 / 042059 A1. Furthermore, the stirred ball mill described in this document has an internal stator that can also be cooled.The agitator is pot-shaped and includes a ring-cylindrical rotor.

[0010] As already mentioned in connection with DE 3614721 A1, cooling can alternatively or additionally be achieved via the agitator rotor. German patent application DE 3015631 A1 describes an agitator consisting of an inner and an outer cylinder, between which an annular cooling chamber is formed. For cooling purposes, a coolant supply pipe is arranged axially parallel within the cooling chamber and is connected to a coolant supply pipe.

[0011] Another coolable agitator shaft is disclosed in patent DE 10241924 B3, wherein tubular material in various cross-sectional shapes is used for cooling, within which an inner tube is arranged that extends over almost the entire length, wherein the interior of the tube is connected to the coolant inlet and the outer space to the coolant outlet.

[0012] Patent DE 41 09 332 C2 also describes a stirring shaft with rod-shaped stirring rods attached to the stirring shaft, which can be cooled via channels.

[0013] Utility model DE 20 2015 101 859 U1 describes a fluid guidance mat with lamellar structures for directing the fluid flow through a cavity. The fluid guidance mat is arranged between the jacket container and the grinding container.

[0014] The patent application WO 2007 / 042059 describes a stirred mill with an inner stator and a ring-cylindrical rotor. The inner stator has an outer wall and a cylindrical inner shell, between which a cooling chamber is formed.

[0015] Above a certain size, ceramic agitator shafts or agitators must be constructed from multiple components. Manufacturing the individual parts to fit together requires extensive grinding, resulting in very high costs due to the labor involved. Furthermore, assembling the agitator shaft from multiple parts creates so-called dead spaces where grinding material and / or grinding aids can become trapped, thus contaminating the machine chamber. Such multi-part ceramic agitator shafts are also very fragile, especially during assembly, disassembly, cleaning, and maintenance. Moreover, it is currently not possible to manufacture ceramic rotors with integrated cooling. Description

[0016] The object of the invention is to manufacture a stirring shaft for a stirred ball mill in a simple and cost-effective manner, in particular a coolable stirring shaft for use in high-performance stirred ball mills.

[0017] The above problem is solved by a stirring shaft for a stirred ball mill, a stirred ball mill, and a method for manufacturing a stirring shaft for a stirred ball mill, comprising the features in the independent claims. Further advantageous embodiments are described in the dependent claims.

[0018] The stirred ball mill is used for processing and, in particular, comminuting material with the aid of grinding aids and has a grinding container with a material inlet and a product outlet, to which an agitator is assigned, which is at least partially located inside the grinding container.

[0019] The agitator comprises a drive, a rotating agitator shaft arranged on the drive and rotating in one direction, and at least one agitator element arranged on the agitator shaft. The agitator shaft has a preferably cylindrical base body with a longitudinal axis, wherein at least one, and preferably a plurality of, agitator elements is / are arranged on the base body. In particular, the agitator shaft has an outer surface equipped with agitator elements. The longitudinal axis of the agitator shaft generally coincides with the longitudinal axis of the grinding container. The drive is generally arranged outside the grinding container and is connected to the agitator shaft located inside the grinding container via a drive shaft that penetrates the container wall.

[0020] The stirring shaft with the stirring elements is formed in one piece and consists of a ceramic material.

[0021] Furthermore, the agitator shaft has at least one cooling channel, which preferably extends at least partially parallel to the longitudinal axis of the agitator shaft. The at least one cooling channel extends in at least two sections parallel to the longitudinal axis of the agitator shaft, with a deflection section formed between the two parallel sections, and in particular, a coolant flows through the at least two sections connected to each other via a deflection section in opposite directions.

[0022] One embodiment provides that the at least one cooling channel is designed in a meandering shape.

[0023] The grinding container is preferably cylindrical and arranged horizontally or vertically, so that the agitator shaft is arranged horizontally or vertically accordingly. The grinding container can also have a different shape and, for example, be frustoconical. In this case, the agitator shaft is preferably also frustoconical.

[0024] The at least one stirring element is designed, for example, as a cam which preferably extends approximately radially away from the stirring shaft towards an inside of the grinding container of the stirred ball mill.

[0025] Between the outer surface of the agitator shaft and the inner surface of the grinding container, an annular grinding gap is formed, containing a mixture of material to be ground and grinding media. Due to the rotation of the agitator shaft, the material within the grinding gap is broken down by stresses such as particle collisions, shear forces, etc. The agitator elements support this process by imparting additional energy, particularly to the grinding media.

[0026] The agitator shaft with the stirring elements is manufactured and formed in one piece and is preferably made of a ceramic material. Particularly preferably, the agitator shaft is made of silicon carbide (SiC), silicon carbide with free silicon (SiSiC), silicon nitride, zirconium oxide, or mixed ceramics. Silicon carbide ceramics exhibit high wear resistance, low thermal shock sensitivity, low thermal expansion, high thermal conductivity, good resistance to acids and alkalis, and are also lightweight and retain their positive properties up to temperatures above 1400°C. Furthermore, silicon carbide is toxicologically harmless and can therefore also be used in the food industry.Although silicon nitride exhibits reduced hardness compared to silicon carbide, a sintering process can induce columnar recrystallization of the β-silicon nitride crystals, resulting in increased fracture toughness. This high fracture toughness, combined with small defect sizes, gives silicon nitride one of the highest strengths among engineering ceramics. The combination of high strength, a low coefficient of thermal expansion, and a relatively low modulus of elasticity makes silicon nitride ceramics particularly suitable for components subjected to thermal shock. In contrast to other ceramic materials, zirconium oxide exhibits very high resistance to crack propagation. Furthermore, zirconium oxide ceramics possess a very high coefficient of thermal expansion and are therefore frequently chosen for bonding ceramics to steel.

[0027] The agitator shaft and agitator elements are preferably manufactured using a 3D printing process. This makes it possible to produce a component with internal cavities that would not be possible in a single process step using conventional methods such as injection molding, without further post-processing, for example, without subsequently drilling holes or similar features. Now, however, it is possible to easily and cost-effectively incorporate at least one integrated cooling channel within the agitator shaft.

[0028] According to one embodiment of the invention, two parallel sections, through which coolant flows in opposite directions, are located on a common radial of the agitator shaft. This achieves counter-current cooling of the agitator shaft. In particular, the coolant is guided from the material inlet side to the product outlet side close to the longitudinal axis of the agitator shaft. The return of the coolant from the product outlet side to the material inlet side takes place within the agitator shaft in a region adjacent to the outer surface of the shaft. This ensures that the freshest and therefore coolest coolant is first introduced into the area of ​​the agitator ball mill where the material being ground is warmest. This is particularly the area near the product outlet after the material being ground has flowed through the agitator ball mill in the conveying direction from the material inlet side.In particular, the coolant flows through the agitator shaft at its surface in the opposite direction to the conveyance of the material being ground through the stirred ball mill. This counterflow cooling allows for further optimization of the cooling process.

[0029] One embodiment of the agitator shaft provides that it comprises at least two sections, in particular a first end section to which the agitator shaft is connected to the drive shaft of the agitator. For example, the first end section has a receiving area, in particular a shaft receptacle, in which the free end of the drive shaft can be arranged and connected to the agitator shaft in a rotationally fixed manner. Furthermore, at least one second section is provided. The second section is preferably hollow. In addition, through-openings are preferably formed in the second section between the outer surface and the hollow interior or interior area. In particular, a plurality of through-openings are provided, extending parallel to the longitudinal axis of the agitator shaft. A separating device may preferably be formed within the second section.The mixture of material to be ground and grinding media flowing through the grinding gap is deflected at the open end of the second section and flows through the separating device into the hollow interior of this section. The separating device, which can be designed, for example, as a separating screen or classifying rotor, retains the grinding media and conveys them, along with any insufficiently ground material, back into the grinding gap through the openings. The sufficiently ground material, on the other hand, is conveyed through the hollow interior to a product outlet of the stirred ball mill, where it can be removed.

[0030] Preferably, the grinding media are concentrated in this so-called grinding chamber due to the small grinding gap between the agitator shaft and the inner wall of the grinding container. Only a small portion of the grinding media is deflected along with the material being ground and flows through the separating device into the hollow interior of the second section.

[0031] According to one embodiment, the second sub-section is a central sub-section to which a further third terminal sub-section is attached. This third sub-section also has a hollow interior. In the case of a cylindrical base body of the agitator shaft, the interiors of the second and, optionally, third sub-sections are preferably also cylindrical and have a circular cross-section, wherein the radius of the cross-section of the interior in the third sub-section is greater than or equal to the radius of the cross-section of the interior in the second sub-section. Furthermore, the cylindrically shaped inner cavities each have a longitudinal axis that is congruent with the longitudinal axis of the agitator shaft.

[0032] In the third section, preferably no openings are provided between the interior and the outer surface of the agitator shaft. Instead, a wear-resistant sleeve, preferably also cylindrical, can be arranged in the interior of the third section. In particular, the wear-resistant sleeve is located between the bottom of the grinding container and the separating device in the second interior area. In this embodiment, the material / grinding aid mixture flowing through the grinding gap is deflected at the open end of the third section within the annular gap formed between the wear-resistant sleeve and the agitator shaft towards the second section, by separating the material from the grinding aids as described above.

[0033] Preferably, the at least one cooling channel extends within the first terminal section and at least partially within the second, middle section. In an embodiment of a stirring shaft comprising three sections, the at least one cooling channel may extend through all three sections. A meandering cooling channel may, for example, include parallel sections formed between through-openings within the second section of the stirring shaft. The parallel sections may extend at least partially into the first and / or third section of the stirring shaft.In particular, corresponding deflection areas are formed at the terminal sections of the first and third sub-sections of the agitator shaft, which deflect the coolant from one parallel section to the next parallel section, so that the coolant preferably flows in opposite directions through directly adjacent parallel sections.

[0034] In particular, it is provided that such a cooling channel comprises an even number of parallel sections, with the coolant inlet and outlet located at the same end of the agitator shaft. In this case, the coolant flows, for example, through the first, third, and fifth parallel sections, etc., in a first flow direction and through the second, fourth, and sixth parallel sections, etc., in an opposite second flow direction. The material to be ground / grinding aid mixture flows through the grinding gap in a first conveying direction, which corresponds, for example, to the first flow direction, and is redirected within the second and / or third subsection of the agitator shaft, in particular, into a second conveying direction, which corresponds to the second flow direction.The cooling water routing, in particular the cooling water supply and discharge, can be formed by an insert part, which can be arranged and attached, for example, together with the drive shaft to the first part section of the agitator shaft; for example, the insert part can be placed on the end of the drive shaft and arranged and attached together with it in the shaft passage, with the cooling water supply and discharge being connected to the at least one cooling channel of the agitator shaft.

[0035] Preferably, a plurality of agitator elements are arranged on the agitator shaft. In particular, a regular arrangement of agitator elements in rows parallel to the longitudinal axis of the agitator shaft and / or arranged successively in a series along a circumferential line of the agitator shaft's base body is provided. All agitator elements can be identical or have different shapes. Furthermore, areas on the agitator shaft can be provided in which more cams are formed than in other areas, etc.

[0036] Preferably, the stirring elements are designed as cams projecting from the base body of the stirring shaft, wherein the connecting surface of the cams formed on the base body is relatively large, particularly in comparison to the height of the cams with which they project radially beyond the base body.

[0037] The cam has a connecting surface formed on the base of the agitator shaft, an upper surface facing the inside of the grinding container, a leading side in the direction of rotation of the agitator shaft, a trailing side in the direction of rotation of the agitator shaft, and two sides arranged between the leading and trailing sides. The leading side is also referred to as the flow-facing side, and the trailing side is also referred to as the side facing away from the flow. The distance between the connecting surface and the upper surface is called the cam height.

[0038] The relatively large contact surface of the cams allows heat from the grinding material / grinding aid mixture to be advantageously dissipated into the agitator shaft and, in particular, into the coolant within the at least one cooling channel of the agitator shaft. The cam shape, described in more detail below, reduces the ceramic material's susceptibility to chipping or breakage. The base body and cams are manufactured together as a monolithic component from a ceramic material, particularly using a 3D printing process, resulting in a direct material bond between the agitator shaft base and the cams. The one-piece design of the agitator shaft promotes both stability and heat conduction, as potential fracture points and heat conduction barriers are eliminated.

[0039] For good stability of the cams and to achieve a consistently good grinding result, it is advantageous if each cam has a connecting surface to the base body of the agitator shaft and a leading side, wherein the ratio of the projection of the leading side onto a plane normal to the base body of the agitator shaft and the size of the connecting surface is less than one.

[0040] The leading side is hereinafter referred to as the frontal flow surface. Preferably, the angle of inclination of the frontal flow surface with respect to the plane perpendicular to the base body can be in a range of -45° to 85°. An angle of 0° corresponds to a flow surface arranged perpendicular to the base body, whereas a negative angle denotes an undercut flow surface, i.e., a flow surface that is inclined in such a way that it essentially covers a certain area of ​​the connecting surface. Positive angles of inclination therefore characterize a frontal flow surface that is inclined in the opposite direction, i.e., where the end of the flow surface located on the base body is the first point of contact with the airflow.

[0041] Furthermore, it has proven advantageous if each cam has a contact surface with the agitator shaft of maximum width, and the ratio of the height of each cam perpendicular to the agitator shaft to its maximum width is greater than 0.2. The contact surface just mentioned corresponds in particular to the base area of ​​each cam and refers to the area with which each cam is in contact with the agitator shaft. It has also proven advantageous if each cam has a contact surface with the agitator shaft of maximum length, and the ratio of the height of each cam to its maximum length is less than one.

[0042] It is also advantageous if each cam has a connecting surface to the stirring shaft with a maximum length and a maximum width, where the ratio of the maximum width to the maximum length is less than one.

[0043] If several cams are arranged successively in a row along a circumferential line of the agitator shaft's base body, it may be advantageous, for example, to select a distance between the successive cams in a row that is equal to or greater than the maximum circumferential length of a cam. If a plurality of cams are arranged successively in a row along several axially spaced circumferential lines, it may be advantageous to select an axial distance between each pair of axially adjacent cam rows that is greater than or equal to 1.1 times the maximum width of a cam. When arranging axially spaced cams on the agitator shaft's base body, the cams may be arranged axially aligned or offset from one another.

[0044] As described above, a wear protection sleeve can be arranged in the third terminal section of the agitator shaft, particularly in the third interior area, and installed within the agitator ball mill in such a way that it can be easily replaced.

[0045] The wear protection sleeve is cylindrical, at least in part, and in particular as a hollow cylinder. The hollow cylinder has an outer diameter that is smaller than the inner diameter of the third interior section. A mounting area, such as a flange, may be provided at one end of the wear protection sleeve to position and secure the sleeve in or to the stirred ball mill.

[0046] In particular, a grinding gap is formed between the inner surface of the agitator shaft in the third interior space and the outer surface of the preferably cylindrical wear protection sleeve, in which the grinding material / grinding aid mixture is guided towards the second interior space of the second section. The wear protection sleeve is preferably also a single piece, made especially of a ceramic material, and can be manufactured, for example, using 3D printing, similar to the agitator shaft.

[0047] Furthermore, the wear protection sleeve may include at least one cooling channel, which may also be meandering, thus providing a large cooling surface. The outer surface of the wear protection sleeve may also be designed with cam-shaped projections. The shape of these projections may, for example, correspond to the shape of the cams described above on the agitator shaft. These projections reduce the gap between the inner surface of the agitator shaft in the third interior area and the outer surface of the wear protection sleeve. The projections serve primarily as scrapers to prevent grinding material and / or grinding aids from adhering to the inner surface of the agitator shaft.Instead, the elevations ensure that the grinding material / grinding aid mixture flows towards the passage openings for returning the grinding aids towards the grinding chamber formed between the outer surface of the agitator shaft and the inner wall of the grinding container.

[0048] The wear protection sleeve can preferably be used in a stirred ball mill in conjunction with the aforementioned agitator shaft. However, the wear protection sleeve can also be used in conjunction with an agitator shaft manufactured using conventional methods. It should be emphasized that the monolithic design of the wear protection sleeve, with or without protrusions on the outer surface and / or with or without at least one cooling channel, constitutes an independent invention.

[0049] A previously described, monolithic stirring shaft with cams or similar features and at least one cooling channel combines the advantages of optimal cooling with maximum wear resistance and is therefore particularly suitable for use in high-performance mills.

[0050] The application also includes, in particular, one-piece agitator shafts, especially those made of a ceramic material, which are designed without a cooling channel. Preferably, these agitator shafts also have at least two differently designed subsections, in particular at least one first terminal subsection for attaching the agitator shaft to a drive shaft and at least one second subsection with a hollow interior and openings between the interior and the outer surface of the agitator shaft in the second subsection.

[0051] It should be expressly mentioned here that all aspects and embodiments explained in connection with the device according to the invention equally relate to, or can relate to, partial aspects of the method according to the invention. Therefore, whenever certain aspects, relationships, and / or effects are mentioned in the description or in the definitions of the claims relating to the device according to the invention, this applies equally to the method according to the invention. Conversely, the same applies, so that all aspects and embodiments explained in connection with the method according to the invention equally relate to, or can relate to, partial aspects of the device according to the invention.Therefore, if at any point in the description or in the claim definitions for the method according to the invention certain aspects and / or relationships and / or effects are mentioned, this applies equally to the device according to the invention. Character description

[0052] The following exemplary embodiments of the invention and its advantages will be explained in more detail with reference to the accompanying figures. The relative sizes of the individual elements in the figures do not always correspond to the actual relative sizes, as some shapes are simplified and others are enlarged for better illustration. Fig. Figure 1 shows a perspective view of an embodiment of a stirring shaft formed in one piece according to the invention. Fig. Figure 2 shows a technical representation of a side view of the agitator shaft according to Fig. 1. Fig. Figure 3 shows a sectional view of the agitator shaft along the section line AA according to Fig. 2. Fig. Figure 4 shows another sectional view of the agitator shaft along the section line BB according to Fig. 3. Fig. Figure 5 shows a technical representation of a perspective view of the stirring shaft. Fig. Figure 6 shows a cut-open agitator shaft with exposed meandering cooling channels. Fig. Figure 7 shows a side view of a wear protection sleeve. Fig. Figure 8 shows a perspective view of the wear protection sleeve. Fig. Figure 9 shows a front view of a stirred ball mill. Fig. Figure 10 shows a sectional view of the stirred ball mill along the section line AA according to Fig. 9. Fig. Figure 11 shows a sectional view of the stirred ball mill along the section line BB according to Fig. 10. Fig. Figure 12 shows a sectional view of the stirred ball mill along the section line CC according to Fig. 11. Fig. Figure 13 shows a sectional view of the stirred ball mill along the section line DD according to Fig. 12. Fig. Figure 14 shows a sectional view of the stirred ball mill according to the section lines EE. Fig. 9. Fig. Figure 15 shows a perspective view of a further embodiment of a one-piece agitator shaft with countercurrent cooling according to the invention. Fig. Figure 16 shows a longitudinal section of a stirred ball mill with a cooling channel designed as counterflow cooling. Fig. Figure 17 shows a cross-section of a stirred ball mill with agitator shaft according to Fig. 16 along a section line AA. Fig. Figures 18A to 18E each show further embodiments of stirring shafts.

[0053] Identical reference numerals are used for identical or equivalently functioning elements of the invention. Furthermore, for the sake of clarity, only those reference numerals necessary for describing the respective figure are shown in the individual figures. The illustrated embodiments merely represent examples of how the device or method according to the invention may be configured and do not constitute an exhaustive limitation.

[0054] Fig. Figures 1 to 6 show different views and sectional representations of a one-piece agitator shaft 1 according to the invention. Such an agitator shaft 1 is preferably used in an agitator ball mill 50, as shown below with reference to the Fig. This is explained in more detail in sections 9 to 14. The agitator shaft 1 has a cylindrical base body 2 with a longitudinal axis L, wherein agitator elements 3, in particular cams 4, are formed on the outer surface of the cylindrical base body 2. The outer surfaces of the cams 4 and the outer surfaces of the cylindrical base body 2 not covered by cams 4 together form the outer surface 5 of the agitator shaft 1. The agitator elements 3 are formed in several rows, in particular in an aligned arrangement, on the outside of the cylindrical base body 2, wherein the rows are arranged and / or formed parallel to the longitudinal axis L of the agitator shaft 1.

[0055] According to the invention, the agitator shaft 1 is formed in one piece and is preferably made of a ceramic material. The agitator shaft 1 is preferably manufactured from the ceramic material in a single process step. A 3D printing process is particularly preferred for this purpose, since this process also allows cavities within the agitator shaft 1 to be created in a single process step.

[0056] The ceramic material can be, for example, silicon carbide (SiC), especially sintered silicon carbide (SSiC), silicon carbide with free silicon (SiSiC), silicon nitride, zirconium oxide, or mixed ceramics. Silicon carbide ceramics exhibit high wear resistance, low thermal shock sensitivity, low thermal expansion, high thermal conductivity, good resistance to acids and alkalis, and are also lightweight and retain their positive properties up to temperatures above 1400°C. Furthermore, silicon carbide is toxicologically harmless and can therefore be used in the food industry. While silicon nitride has a lower hardness compared to silicon carbide, a sintering process can induce columnar recrystallization of the β-silicon nitride crystals, resulting in increased fracture toughness of the material.Silicon nitride's high fracture toughness, combined with small defect sizes, gives it one of the highest strengths among engineering ceramics. The combination of high strength, a low coefficient of thermal expansion, and a relatively low modulus of elasticity makes silicon nitride ceramics particularly suitable for components subjected to thermal shock. In contrast to other ceramic materials, zirconium oxide exhibits very high resistance to crack propagation. Furthermore, zirconium oxide ceramics possess a very high coefficient of thermal expansion and are therefore frequently chosen for bonding ceramics to steel.

[0057] In the technical representation of a side view of the agitator shaft 1 according to Fig. 2 and in the cutaway view according to Fig. Figure 6 shows a cooling channel 6 formed within the one-piece agitator shaft 1. Preferably, this extends at least partially parallel to the longitudinal axis L of the agitator shaft 1. It is particularly preferred that the cooling channel 6 extends in a meandering shape between the end regions of the agitator shaft 1 and is deflected at each end region, with the regions between the deflections being arranged substantially parallel to each other. Fig. Figure 2 shows, for example, three parallel sections 61, 62, 63 of the cooling channel 6, which are parallel to each other and also arranged parallel to the longitudinal axis L of the agitator shaft. Between the three parallel sections 61, 62, 63, two deflection sections 67, 68 are formed in the end regions of the agitator shaft 1.

[0058] A coolant flowing through the first parallel section 61 in a first flow direction SR1 is deflected in the first deflection area 67 into the second parallel section 62 and flows through it in a second flow direction SR2, which runs opposite to the first flow direction SR1. Subsequently, the coolant is deflected in the second deflection area 68 into the third parallel section 63 and flows through it again in the first flow direction SR1.

[0059] The in Fig. 3 Sectional view of the agitator shaft 1 along the section line AA according to Fig. Figure 2 shows that the cooling channel 6 formed within the agitator shaft 1 has six parallel sections 61, 62, 63, 64, 65 and 66, each of which is connected by a first deflection section 67, the second parallel section 62 and the third parallel section 63 via a second deflection section 68, the third parallel section 63 and the fourth parallel section 64 via a third deflection section (not shown), the fourth parallel section 64 and the fifth parallel section 65 via a fourth deflection section (not shown), and the fifth parallel section 65 and the sixth parallel section 66 via a fifth deflection section 69 (compare Figure 2). Fig. 6) are connected. In particular, it can be provided that the coolant is introduced into the agitator shaft 1 via the first parallel section 61 of the cooling channel 6 and is discharged from the agitator shaft 1 via the sixth parallel section 66 of the cooling channel 6.

[0060] The agitator shaft 1 has three sections, in particular a first end section I, a second middle section II, and a third end section III. The agitator shaft 1 can be connected at its first end section I to a drive shaft 70 of the stirred ball mill (not shown). For this purpose, a shaft receptacle 7 is provided in the first end section I. The agitator shaft 1 is designed at least partially as a hollow shaft; in particular, the second section II and the third section III, and optionally, the first section I, each have interior spaces. In particular, the second middle section II has a first hollow interior space 12, and the third section III has a second hollow interior space 13.These preferably also have a cylindrical shape, the longitudinal axis of which is congruent with the longitudinal axis L of the agitator shaft 1. Furthermore, it is provided that the third part – section III – is open at its end and, in particular, has a further enlarged hollow interior in this open area. As will be discussed below in connection with the... Fig. As explained in sections 9 to 14, a wear element or similar can be arranged in this hollow interior space.

[0061] Furthermore, it may be provided that in the second central part – section II – between the hollow interior area 12 and the outer surface 5 of the agitator shaft 1, passage openings 15 are formed, the function of which will also be described below in connection with the Fig. Sections 9 to 14 are explained. The second middle section II is therefore also referred to as the open section, while the first section I and the third section III are each closed sections. The passage openings 15 extend, in particular, parallel to the longitudinal axis L of the agitator shaft, preferably between the rows of agitator elements 3, as they are used in particular in connection with Fig. 1 have been described.

[0062] For example, as demonstrated by the Fig. As can be clearly seen in Figure 6, the at least one cooling channel 6 preferably extends through all three sections I, II and III of the agitator shaft 1, with the deflection areas 67, 68, 69 being formed in the end sections I and III, respectively. In particular, the cooling channel 6 can be meandering – this will be described in more detail below.

[0063] Fig. Figure 4 shows a longitudinal section of the agitator shaft 1, in particular a sectional view of the agitator shaft 1 along the section line BB according to Fig. 3. At Fig. Figure 3 is in particular a cross-section of the agitator shaft 1 in the second part – section II, which passes through the agitator elements 3. The openings 15 between the first hollow inner area 12 and the outer surface 5 of the agitator shaft 1 are clearly visible. Fig. 4 can be seen that the cooling channel 6 is designed in particular parallel to the longitudinal axis L and to the parallel-axially extending passage openings 15, wherein a parallel section 61, 62, 63, 64, 65, 66 of the cooling channel 6 extends adjacent to a series of stirring elements 3.

[0064] Fig. Figure 7 shows a side view of a wear protection sleeve 30 and Fig. Figure 8 shows a perspective view of the wear protection sleeve 30. The arrangement of the wear protection sleeve 30 within a stirred ball mill 50 and its function are discussed in particular in connection with the Fig. 10, Fig. 12 and Fig. 13 described below.

[0065] The wear protection sleeve 30 is at least partially cylindrical; in particular, the wear protection sleeve 30 has a hollow cylinder 33 as its base body 32, preferably with projections 34 on its outer surface, especially in the form of cams 35 as described in more detail below. The hollow cylinder has an outer diameter d30 that is smaller than the smallest inner diameter dIII of the third interior area in the third section III of the agitator shaft 1 (compare Fig. 2) A fastening area, for example a flange 36, can be provided at one end of the wear protection sleeve 30 in order to position and fasten the wear protection sleeve 30 in or on the stirred ball mill 50, in particular to secure the wear protection sleeve 30 to the grinding container bottom 59, especially in a suitable receptacle on the grinding container bottom 59 - compare Fig. 10 and Fig. 12.

[0066] The wear protection sleeve 30 is preferably also made in one piece and in particular from a ceramic material and can be manufactured analogously to the stirring shaft 1, for example, using 3D printing from one of the ceramic materials described above.

[0067] Furthermore, the wear protection sleeve 30 may include at least one cooling channel, which, for example, is also meander-shaped and thus forms a large cooling surface (not shown). The design of the at least one cooling channel of the wear protection sleeve may correspond to the design of a cooling channel 6 of the agitator shaft 1. The coolant supply and discharge lines may, for example, pass through the bottom of the grinding container (59, compare Fig. 10, Fig. 12) be trained.

[0068] The wear protection sleeve 30 can preferably be installed in a way that is Fig. 9 to 14 illustrated stirred ball mill 50 with a stirring shaft 1 according to the Fig. 1 to 6 can be used. However, the wear protection sleeve 30 can also be used in conjunction with a stirring shaft manufactured using conventional methods.

[0069] Fig. Figures 9 to 14 show different views and representations of a stirred ball mill 50 with agitator shaft 1 according to the invention, in particular showing Fig. 9 a front view of a stirred ball mill 50, Fig. Figure 10 shows a sectional view of the stirred ball mill along the section line AA according to Fig. 9 and Fig. Figure 11 shows a sectional view of the stirred ball mill 50 along the section line BB according to Fig. 10.

[0070] The stirred ball mill 50 comprises a cylindrical grinding chamber 51 extending along a horizontal axis L50, with an inner surface 52. The grinding chamber 51 can be made of a metal or, analogous to the agitator shaft 1, of a ceramic material. Furthermore, the grinding chamber can be designed to be cooled and may, for example, comprise an outer cylinder 53 and an inner cylinder 54, between which a cooling chamber 55 is formed. Coolant K can be introduced into this cooling chamber via a suitable coolant inlet 56 and a coolant outlet 57. The grinding chamber 51 also comprises a grinding chamber lid 58 and a grinding chamber bottom 59.

[0071] Inside the grinding container 51, a stirring shaft 1 with a longitudinal axis L is arranged horizontally. The longitudinal axis L of the stirring shaft 1 simultaneously represents its axis of rotation and is also congruent with the horizontal axis L50 of the grinding container 51. The stirring shaft 1 corresponds to the one described in the Fig. 1 to 6 described stirring shaft 1, so that reference is made to it for the description of its characteristics.

[0072] A drive shaft 70 extends through the grinding container lid 58 and is connected to a drive, for example an electric motor or similar (not shown). The drive shaft 70 is rotationally fixed to the agitator shaft 1; in particular, the end of the drive shaft 70 projecting into the grinding container 51 engages in the shaft receptacle 7 in the first section I of the agitator shaft 1. Furthermore, the grinding container lid 58 includes the material inlet 71, through which the material M is fed into the agitator ball mill 50. A product outlet 72 is provided in the bottom 59 of the grinding container, through which the ground product P leaves the agitator ball mill 50.

[0073] An annular grinding gap MS is formed between the inner surface 52 of the grinding container 51 and the outer surface 5 of the agitator shaft, particularly in the area of ​​the agitator elements 3. During operation of the stirred ball mill 50, the material to be ground / grinding media mixture is located within this gap. By rotating the agitator shaft 1 in combination with the grinding media (not shown), the material to be ground M is moved within the grinding gap MS from the material inlet side to the product outlet side and is thereby subjected to such stress that it is comminuted, for example, by collisions between particles of the material being ground, by collisions between particles of the material being ground and grinding media, by shear forces, etc.To enhance the comminution effect, it may be provided that projections such as cams, rods or similar elements may also be arranged on the inner surface 52 of the grinding container 51, which on the one hand cause additional mixing of the grinding material / grinding aid mixture and on the other hand increase, for example, the number of collision processes taking place in the grinding gap MS and thus increase the comminution effect of the stirred ball mill 50.

[0074] Furthermore, the product outlet 72 is formed within a so-called receiving section 75, which extends through a central opening in the grinding container base 59. This receiving section 75 may also have cooling channels 76 through which coolant K is passed to cool the product P. The receiving section 75 extends axially, in particular, within the inner cavity of the agitator shaft 1 towards the material inlet 71 and is partially surrounded by the wear-resistant sleeve 30 in the area of ​​the product outlet 72. At the end region of the receiving section 75, which is arranged axially opposite the product outlet 72, a separating screen 40, which will be described in more detail below, is preferably arranged. This screen serves to retain the grinding aids in the interior of the stirred ball mill while the product P is removed.

[0075] The in Fig. Figure 11 shows a cross-section of the stirred ball mill 50, in particular a cross-section in the area of ​​the second central part-section II of the stirring shaft 1, comparable to Fig. 3. The detailed enlargement shows in particular an alternative embodiment of a cooling channel 6*, which does not have a circular cross-section, but is designed with an optimized, enlarged cross-section.

[0076] In this context, the shape of the cams 4 will be discussed in more detail. As already described, the agitator shaft 1 is manufactured in one piece; in particular, the agitator elements 3 are formed directly during the manufacturing of the agitator shaft 1 and are not attached subsequently. The agitator elements 3 are specifically designed as cams 4 projecting from the cylindrical base body 2 of the agitator shaft 1. The contact surface 20 of the cams 4 formed on the base body 2 of the agitator shaft 1 is relatively large, especially in relation to the radial height h of the cams 4. The shape of the cams 4 can assume any geometric form in both axial and radial sections, for example, trapezoidal, with rounded corners, with chamfered edges, etc.The connecting surface 20 corresponds in particular to a base surface of each cam 4 and means the surface with which each cam 4 is in contact with the outer surface of the agitator shaft 1.

[0077] Since, in the illustrated embodiment, the cooling channel 6, 6* is formed adjacent to the cams 4, heat from the material being ground / grinding aid mixture can be advantageously dissipated into the coolant within the cooling channel 6, 6* via the large contact surface 20 of the cams 4, as the large contact surface 20 dissipates the heat more effectively. Furthermore, the shape significantly reduces the susceptibility of the cams 4 to breakage or chipping, which is particularly noticeable with ceramic materials. The one-piece design of the agitator shaft 1 promotes both stability and heat conduction, as potential fracture points and heat conduction barriers are eliminated.

[0078] For good stability of the cams 4 and to achieve a consistently good grinding result, it is advantageous if each cam 4 has a connecting surface 20 to the base body 2 of the agitator shaft 1 and a frontal flow surface 21 (see also Fig. 1), wherein the ratio of a projection of the frontal flow surface 21 onto a plane perpendicular to the base body 2 of the stirring shaft 1 and the size of the connecting surface 20 is less than 1.

[0079] It is advantageous, for example, if each cam 4 has a connecting surface 20 to the agitator shaft 1 with a maximum width and the ratio of the height of each cam 4 normal to the agitator shaft 1 to its maximum width is greater than 0.2. Furthermore, each cam 4 can have a connecting surface 20 to the agitator shaft 1 with a maximum length, wherein the ratio of the height of each cam 4 to its maximum length is preferably less than one. According to a further embodiment, it is advantageous if each cam 4 has a connecting surface 20 to the agitator shaft 1 with a maximum length and a maximum width, wherein the ratio of the maximum width to the maximum length is less than one.

[0080] In this context, reference is also made to the Fig. referred to 18A to 18E. Fig. Figures 18A to 18E each show further embodiments of agitator shafts 1. These each show a cross-section of the outer shell surface 5, with the representation of the through-openings, cooling channels, etc. analogous to Fig. 3 was omitted here. In particular, the arrangement and design of the stirring elements 3 or cams 4 on the outer surface 5 differ in the various embodiments. For example, the inclination of the side or inflow surface 21 leading in the direction of rotation D and the inclination of the side lagging in the direction of rotation D are of different degrees.

[0081] The angle of inclination of the frontal inlet surface 21 with respect to a plane normal to the inside of the grinding container 59 and / or a plane normal to the cylindrical outer surface of the agitator shaft 1 can lie within a range of -45° to 85°. An angle of 0° corresponds to an inlet surface 21 that lies within a plane normal to the inside of the grinding container 51 (compare Fig. 18C), whereas an angle with a negative sign denotes an undercut flow surface 21, i.e., a flow surface 21 which is inclined in such a way that it quasi-covers a certain area of ​​the connecting surface 20 (compare in particular Fig. 18D, Fig. 18E). Accordingly, angles of inclination with a positive sign indicate a frontal flow surface 21 that is inclined in the opposite direction, i.e., where the end of the flow surface 21 located on the base body 2 is first exposed to the flow (compare in particular Fig. 18A, Fig. 18B, Fig. 18E).

[0082] In principle, it is advantageous to provide a large number of cams 4 on the agitator shaft 1 to promote the desired interaction with the material being ground / grinding aid mixture. The agitator shaft 1 can also have cam-free areas, or it can have more cams 4 in some areas and fewer in others. Furthermore, not all cams 4 need to be identical, but can be arranged in different shapes and sizes in different areas.

[0083] As can be seen in particular from the Fig. As can be seen from Figure 1, it can be advantageous to arrange several cams 4 consecutively in a row along a circumferential line of the base body 2 of the agitator shaft 1. For example, the distance between successive cams 4 in a row in the circumferential direction can be equal to or greater than the greatest length of a cam 4 in the circumferential direction.

[0084] If a plurality of cams 4 are arranged successively in a row along several axially spaced circumferential lines, then an axial distance between each pair of axially adjacent cam rows greater than or equal to 1.1 times the greatest width of a cam 4 is advantageous. If cams 4 are formed axially spaced from each other on the base body 2 of the agitator shaft 1, then these cams 4 can either be axially aligned or offset from each other.

[0085] Based on the sectional view Fig. 12, which the stirred ball mill 50 along the section line CC according to Fig. Figure 11 shows in particular the path of the material to be ground / grinding media mixture G within the stirred ball mill 50. Material to be ground M is fed into the interior of the grinding container 51 via the material inlet 71. This container is already partially filled with grinding media; for example, the interior of the grinding container is already approximately 80% filled with grinding media. Due to the rotation of the agitator shaft 1, the material to be ground M and the grinding media (not shown) are mixed to form a material to be ground / grinding media mixture G, which flows along the agitator shaft 1 between the inner surface 52 of the grinding container 51 and the outer surface 5 of the agitator shaft 1 in a first conveying direction FR1 towards the bottom 59 of the grinding container.Between the open end region of the third part-section III of the agitator shaft 1 and the grinding container bottom 59 a distance is formed in which the flow of the grinding material / grinding aid mixture G is deflected, so that it now flows through the second hollow interior region 13 of the third part-section III of the agitator shaft 1 in a second conveying direction FR2 opposite to the first conveying direction FR1.

[0086] Within the second interior area 13 is a wear protection sleeve 30 (see also Fig. 10) arranged. Such a wear protection sleeve 30 was already used in connection with the Fig. 7 and Fig. 8, to which reference is made hereby made. Between the inner surface of the agitator shaft 1 in the third interior area 13 and the outer surface of the wear protection sleeve 30, a grinding gap is formed in which the material to be ground / grinding aid mixture G is guided in the conveying direction FR2 towards the first hollow interior area 12 of the second central section II. This grinding gap is particularly small between the cams 35 of the wear protection sleeve 30 and the inner surface of the agitator shaft 1 in the third interior area 13. The cams 35 serve primarily as scrapers to prevent the material to be ground and / or grinding aids from adhering to the inner surface of the agitator shaft 1.Instead, the cams 35 ensure that the grinding material / grinding aid mixture G is kept in flow and fed in conveying direction FR2 to the through-openings 15 in the second part-section, where a return of the grinding aids takes place in the direction of the grinding chamber or grinding gap MS formed between the outer shell surface of the agitator shaft 1 and the inner shell surface 52 of the grinding container 51.

[0087] Within the first hollow interior space 12, a separating screen 40, a classifying rotor 41, or another suitable device is arranged to retain the grinding aids of the material to be ground / grinding aid mixture G, while sufficiently ground material passes through as finished product P and can be removed from the stirred ball mill 50 via the product outlet 72. The grinding aids retained by the separating screen 40, the classifying rotor 41, or similar device, and any insufficiently ground material M, pass through the openings 15 in the second central section II of the agitator shaft 1 back into the grinding gap MS between the grinding container 51 and the agitator shaft 1 and are moved again in the conveying direction FR1.

[0088] Fig. Figure 13 shows a sectional view of the stirred ball mill 50 along the section line DD according to Fig. 12, in which the arrangement of the wear protection sleeve 30 within the second hollow interior area 13 of the third part-section III of the agitator shaft 1 can be seen

[0089] Fig. Figure 14 shows a sectional view of the stirred ball mill 50 with a meandering cooling channel 6 according to the section lines EE. Fig. 9. In particular, the course of the first parallel section 61 of the cooling channel 6 and the course of the sixth parallel section 66 of the cooling channel 6 are visible here. The coolant K is supplied via the coolant inlet 56 and flows through the first parallel section 61 of the cooling channel 6 in a first flow direction SR1. As in connection with Fig. As described in section 6, the coolant 6 is deflected several times and finally flows through the sixth parallel section 66 of the cooling channel 6 in a second flow direction SR2, opposite to the first flow direction SR1, before it is discharged from the agitator shaft 1 via the coolant outlet 57.

[0090] Fig. Figure 15 shows a perspective view of a further embodiment of a one-piece agitator shaft 1 according to the invention. In this embodiment, the illustration of the agitator elements 3, in particular cams 4, as well as the more detailed description of the features of the three sub-sections I, II and III, has been partially omitted. The information related to Fig. However, the features described in section 1 also apply to this embodiment, since the following section will focus in more detail on the design of the at least one cooling channel 6.

[0091] The cooling channel 6 shown here represents a so-called counterflow cooling system. On a first radial R1 extending between the longitudinal axis L and the outer surface 5 of the agitator shaft 1, the cooling channel 6 has two parallel sections 81, 82. In particular, it is provided that the coolant is introduced into the first parallel section 81 and flows through it in a first flow direction SR1 from the first sub-section I towards the third sub-section III, wherein the first flow direction SR1 preferably corresponds to the first conveying direction FR1 for the material / grinding aid mixture G according to the Fig. 9 to 14. In counterflow cooling, it is provided in particular that the coolant K flows successively through two parallel sections 81 and 82, 83 and 84, 85 and 86, 87 and 88, each located on a common radial R, R1, R2, R3, R4 of the agitator shaft 1. In particular, the parallel section 81, 83, 85, 87, which is closer to the longitudinal axis L, is first flowed through by coolant K. Subsequently, in the end region of the third sub-section III, the coolant K is deflected in a deflection area 95 into the parallel section 82, 84, 86 or 88, which is located on the same radial R1, R2 or R3, and flows through it in a second flow direction SR2, opposite to the first flow direction SR1.In the free end region of the first sub-section I, a deflection section 91 is formed, which diverts the coolant K from the second parallel section 82 on the first radial R2 into the third parallel section 83 on the second radial R2, which is formed closer to the longitudinal axis L of the agitator shaft. The coolant then flows through the third parallel section 83 again in the first flow direction SR1 and can subsequently be deflected via a further deflection section 95 in the third sub-section III into the fourth parallel section 84, which is formed on the same second radial R2 but further away from the longitudinal axis L, and so on. Finally, the coolant flows through the last parallel section 88, formed on the fourth radial R4, in the second flow direction SR2 and is discharged from the agitator shaft 1. In the counterflow cooling described here, there are two parallel sections 81 and 82, 83 and 84, etc., running parallel to each other.The cooling channel 6, through which coolant K flows in opposite directions SR1 and SR2, is located on a common radial R of the agitator shaft 1. Specifically, the coolant K is guided from the material inlet side to the product outlet side close to the longitudinal axis L of the agitator shaft 1. The return of the coolant K from the product outlet side to the material inlet side takes place within the agitator shaft 1 in a region adjacent to the outer surface of the agitator shaft 1.

[0092] Preferably, the coolant K does not flow through the parallel sections 81 to 88 sequentially, but rather fresh coolant K flows into each of the parallel sections 81, 83, 85, 87 located closer to the longitudinal axis L and is discharged from the parallel sections 82, 84, 86, 88 located closer to the outer surface of the agitator shaft 1. The deflection area 91 is configured as an annular gap 92. This ensures that the freshest and therefore coolest coolant K is first introduced into the area of ​​the agitated ball mill where the material being ground is warmest. This is particularly the area near the product outlet, after the material being ground has flowed through the agitated ball mill from the inlet side. This counterflow cooling further optimizes the cooling process.

[0093] Fig. Figure 16 shows a longitudinal section of a stirred ball mill with a further embodiment of a stirring shaft 1 with a cooling channel 6 designed as counterflow cooling and Fig. Figure 17 shows a cross-section of the stirred ball mill with agitator shaft according to Fig. 16 along a section line AA. It is provided that the coolant is supplied in a first flow direction SR1 via a coolant supply line 93 within the drive shaft 70 of the agitator shaft 1 and flows through this shaft in the flow direction SR1 via first parallel sections 81 of the cooling channel 6. This first flow direction SR1 preferably corresponds to the first conveying direction FR1 for the material to be ground / grinding aid mixture G according to the Fig. 9 to 14. The first parallel sections 81 are also referred to as inner flow channel 94.

[0094] In the end region of the third subsection III, a deflection section 95 is formed, which connects an inner flow channel 94 with a second parallel section 82 of the cooling channel 6. The second parallel section 82 is also referred to as the outer flow channel 96. In particular, the coolant K is deflected in the deflection section 95 and now flows through an outer flow channel 96 in a second flow direction SR2, opposite to the first flow direction SR1, and then exits the agitator shaft 1 via coolant discharge lines 97 within the drive shaft 70. An inner flow channel 94 and an outer flow channel 96 are each arranged on a radial R of the agitator shaft 1, with the inner flow channel 94 being located closer to the longitudinal axis L of the agitator shaft 1 than the outer flow channel 96.

[0095] In this type of counterflow cooling, two parallel sections 81 and 82 of the cooling channel 6 are located on a common radial R of the agitator shaft 1 and are traversed by the coolant K in opposite flow directions SR1, SR2. A particular advantage here is that the coolant K is discharged after it has flowed through the agitator shaft 1 once in the first flow direction SR1 and once in the second flow direction SR2. Thus, all parallel sections 82 are cooled equally, whereas in the 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. Thus, the cooling of a stirring shaft 1 is as follows: Fig. 16 compared to the cooling of a first embodiment of the agitator shaft 1 according to Fig. Optimized 15 times further.

[0096] In Fig. Figure 16 further illustrates the feeding of the grinding material M, the flow guidance of the grinding material / grinding aid mixture G within the stirred ball mill 50 and the removal of product P - see also the description of Fig. 12.

[0097] Furthermore, embodiments are conceivable in which an annular gap is formed in the first section I of the agitator shaft 1 for the coolant supply. From this annular gap, a plurality of cooling channels extend in a first flow direction SR1 towards the third section III. Here, several deflection channels are formed, which then return the cooling medium in a second flow direction SR2, counter-current to the first flow direction SR1 and counter-current to the conveying direction FR of the grinding material / grinding aid mixture G, in particular to another annular gap, which collects and discharges the "used" cooling medium. This ensures that each shaft section is cooled with fresh coolant.

[0098] The embodiments, examples, and variants described in the preceding paragraphs, the claims, or the following description and the figures, including their various views or individual features, may be used independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, provided the features are not incompatible.

[0099] Although the figures are generally referred to as "schematic" representations and views, this does not mean that the figure representations and their descriptions are of minor importance with regard to the disclosure of the invention. A person skilled in the art is perfectly capable of extracting enough information from the schematic and abstract drawings to facilitate their understanding of the invention, without their understanding being impaired in any way by the drawn and possibly not exactly to-scale dimensions of the components and / or parts of the device or other drawn elements.The figures thus enable the expert reader to derive a better understanding of the inventive concept formulated in the claims and in the general part of the description of general and / or abstract concepts, based on the more concretely explained implementations of the inventive method and the more concretely explained functioning of the inventive device.

[0100] The invention has been described with reference to a preferred embodiment. However, it is conceivable to a person skilled in the art that modifications or alterations of the invention can be made without departing from the scope of protection of the following claims. List of reference symbols 1 stirring shaft 2 cylindrical base bodies 3 Stirring element 4 cam 5 Outer shell area 6.6* Cooling channel 7 wave recording 12 first interior area 13 second interior area 15 Passage opening 20 connecting surface 21 frontal flow area 30 Wear protection sleeve 32 cylindrical base bodies 33 hollow cylinders 34 Survey 35 Cam 36 flange 40 separating sieve 41 Classifying rotor 50 Stirred Ball Mill 51 grinding containers 52 Inner surface area 53 external cylinders 54 internal cylinders 55 Cold storage room 56 Coolant inlet 57 Coolant outlet 58 grinding container lids 59 Grinding container bottom 61 (first) parallel section of the cooling channel 62 (second) parallel section of the cooling channel 63 (third) parallel section of the cooling channel 64 (fourth) parallel section of the cooling channel 65 (fifth) parallel section of the cooling channel 66 (sixth) parallel section of the cooling channel 67 (first) deflection area of ​​the cooling channel 68 (second) deflection area of ​​the cooling channel 69 (fifth) deflection area of ​​the cooling channel 70 Drive shaft 71 Grinding material inlet 72 Product outlet 75 Recording section 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 Deflection area 92 annular gap 93 Coolant supply line 94 inner flow channel 95 Deflection range 96 outer flow channel 97 Coolant drain line d30 outer diameter wear protection sleeve dIII Inner diameter third subsection Direction of rotation FR1 first conveying direction FR2 second direction of flow G Grinding material / grinding aid mixture h height of the cams I first terminal sub-section II second middle section III third terminal part-section K Coolant L Longitudinal axis of the stirring shaft L50 horizontal axis of the grinding container of the stirred ball mill M Ground material MS Mahlspalt P Product R Radials R1 first radials R2 second radial R3 third radial R4 fourth radial SR1 first flow direction SR2 second flow direction

Claims

[1] Agitator shaft (1) for an agitator ball mill (50), wherein the agitator shaft (1) has a longitudinal axis (L) and an outer circumferential surface (5) equipped with agitating elements (3), wherein the agitator shaft (1) is formed integrally with the agitating elements (3) and consists of a ceramic material, wherein the agitator shaft (1) has at least one cooling channel (6) which preferably extends at least partially parallel to the longitudinal axis (L) of the agitator shaft (1), wherein the at least one cooling channel (6) extends in at least two regions each parallel to the longitudinal axis (L) of the agitator shaft (1), wherein a deflection region (67) is formed between the two parallel regions (61, 62), in particular wherein a coolant flows through the at least two regions (61, 62) connected to one another via a deflection region (67) in opposite flow directions (SR1, SR2). [2] Stirring shaft (1) according to claim 1, wherein the at least one cooling channel (6) is formed in a meandering shape. [3] Stirring shaft (1) according to claim 1 or 2, wherein two parallel regions (61, 62) through which coolant flows in opposite flow directions (SR1, SR2) are arranged on a common radial (R1, R2 or R3) of the stirring shaft (1). [4] Stirring shaft (1) according to one of the preceding claims, wherein the stirring shaft (1) has a first terminal partial section (I) at which the stirring shaft (1) can be arranged on a drive shaft (70), wherein the stirring shaft (1) further has a second middle partial section (II) and a third terminal partial section (III). [5] Stirring shaft (1) according to claim 3, wherein the at least one cooling channel (6) extends within the first terminal sub-section (I) and at least partially within the second, middle sub-section (II), in particular wherein the at least one cooling channel (6) extends through all three sub-sections (I, II, III). [6] Agitator shaft (1) according to claim 4 or 5, wherein the second, middle section (II) has a first hollow interior (12), in particular a cylindrically shaped first hollow interior (12) with a longitudinal axis which is congruent with the longitudinal axis (L) of the agitator shaft (1). [7] Agitator shaft (1) according to claim 4 or 5, wherein the third terminal subsection (III) has a second hollow interior space (13), in particular a cylindrically shaped second hollow interior space (13) with a longitudinal axis which is congruent with the longitudinal axis (L) of the agitator shaft (1). [8] Stirring shaft (1) according to claim 6, wherein passage openings (15) are formed between the first hollow interior space (12) of the second, middle sub-section (II) and the outer circumferential surface (5) of the stirring shaft (1) in the region of the second, middle sub-section (II). [9] Agitator shaft (1) according to one of the preceding claims, wherein the agitator elements (3) are designed as cams (4) projecting from a base body (2) of the agitator shaft (1), wherein the connecting surface (20) of the cams (4) formed on the base body (2) is relatively large, in particular wherein each cam (4) has a connecting surface (20) to a base body (2) of the agitator shaft (1) and a leading side, wherein a ratio of the projection of the leading side onto a plane normal to the base body (2) of the agitator shaft (1) and the size of the connecting surface (20) is less than 1. [10] Stirring shaft (1) according to one of the preceding claims, wherein the stirring shaft (1) with the stirring elements (3) can be produced by 3D printing. [11] Agitator ball mill (50) with a grinding container (51) extending along a horizontal or vertical axis (L50) and having an inner circumferential surface (52), with an agitator shaft (1) rotatable within the grinding container (51) about the horizontal or vertical axis (L50) and having an outer circumferential surface (5), wherein agitator elements (3) are formed on the outer circumferential surface (5), wherein a grinding gap (MS) is formed between the agitator elements (3) of the agitator shaft (1) and the inner circumferential surface (52) of the grinding container (51), wherein the agitator shaft (1) is formed in one piece with the agitator elements (3) and consists of a ceramic material, wherein the agitator shaft (1) has at least one cooling channel (6), which preferably extends at least partially parallel to the longitudinal axis (L) of the agitator shaft (1), wherein the at least one cooling channel (6) extends in at least two regions (61, 62) each parallel to the longitudinal axis (L) of the agitator shaft (1) extends,wherein a deflection region (67) is formed between the two parallel regions (61, 62), in particular wherein a coolant flows through the at least two regions (61, 61) connected to one another via a deflection region (67) in opposite flow directions (SR1, SR2). [12] Agitator ball mill (50) according to claim 1 with an agitator shaft (1) according to one of claims 2 to 10. [13] Agitator ball mill (50) according to claim 11 or 12, comprising a wear protection sleeve (30) which can be arranged in an interior of the agitator shaft (1), which consists of a ceramic material and is formed in one piece. [14] Method for producing an agitator shaft (1) for an agitator ball mill (50), wherein the agitator shaft (1) is manufactured in one piece from a ceramic material, wherein the agitator shaft (1) has at least one cooling channel (6) which preferably extends at least partially parallel to the longitudinal axis (L) of the agitator shaft (1), wherein the at least one cooling channel (6) extends in at least two regions (61, 62) each parallel to the longitudinal axis (L) of the agitator shaft (1), wherein a deflection region (67) is formed between the two parallel regions (61, 62), in particular wherein a coolant flows through the at least two regions (61, 62) connected to one another via a deflection region (67) in opposite flow directions (SR1, SR2). [15] Method according to claim 14 for producing a stirring shaft (1) according to one of claims 2 to 10, in particular wherein the stirring shaft (1) with the stirring elements (3) is produced by means of 3D printing.

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