Crusher rotor

Abstract

The present disclosure relates to a rotor (108) for a comminution device (100), the rotor (108) being arranged to emit material to be comminuted towards a surface (218), such as an anvil or a self-generated layer of broken material, the rotor (108) comprising a frame (202) comprising an upper plate (204), a lower plate (208) and a wall element (208) extending between the upper plate (204) and the lower plate (206), the rotor (108) further comprising an inlet opening (210) in the upper plate (204) and an outlet (212) between the upper plate (204) and the lower plate (206), wherein the uppermost surface (304) of the frame (202) and the lowermost surface (306) of the frame (202) have a greater hardness than the rest of the frame (202) such that additional wear protection elements can be omitted at those uppermost and lowermost surfaces (304, 306).

Description

TECHNICAL FIELD

[0001] The present invention relates to a crushing plant for crushing rock, ore or the like. More specifically, the present invention relates to a so-called vertical shaft impact crusher. BACKGROUND

[0002] When crushing or grinding rock, ore, cement clinker and other hard materials, a vertical shaft impact crusher with a rotor rotating around a vertical axis can be used. The material to be crushed is fed through centrally arranged openings in the upper plate of the rotor. A distributor plate is arranged at the upper surface of the lower plate of the rotor. When the material to be crushed hits the rotating distributor plate, the material will be dragged generally radially outwards and hit an outer crushing surface, which typically comprises a build-up of the material to be crushed created on the inner surface of the crushing chamber, resulting in self-crushing. Such self-crushing has proven to guarantee excellent shaped particles, e.g. aggregates. However, in the current rotors there are problems with the balance of the rotor and the vibrations of the rotor when the crusher is in operation. Furthermore, there is a lot of machining involved during the manufacturing process, which makes the rotor manufacturing challenging.

[0003] To solve this problem, US patent application US 4923131 proposes a rotating impact crusher rotor with a generally triangular shape, which can be made of a coarse grade low carbon steel, on the outer surface of which a hard facing material is applied. International patent application WO2018 / 005836 proposes a reversible vertical impact crusher comprising a rotor with an upper plate and a lower plate, wherein the rotor comprises wear plates. The problem with the solutions disclosed by US 4923131 A and WO2018 / 005836 is that the manufacturing is complex and it is not easy to achieve a balance. Therefore, there is a need in the art for a more user-friendly rotor manufacturing process, and to provide a rotor wherein the balancing is simplified and the vibrations of the rotor are reduced. SUMMARY

[0004] It is an object to alleviate, mitigate or eliminate one or more of the above-mentioned drawbacks and disadvantages in the art, either individually or in any combination, and to solve at least the above-mentioned problems.

[0005] According to a first aspect, there is provided a rotor for a shredding apparatus, the rotor being arranged to emit material to be shredded towards a surface, such as an anvil or an autogenous layer of broken material, the rotor comprising a frame comprising an upper plate, a lower plate and a wall element extending between the upper plate and the lower plate, the rotor further comprising an inlet opening in the upper plate and an outlet between the upper plate and the lower plate, wherein the uppermost surface of the frame and the lowermost surface of the frame have a greater hardness than the rest of the frame, such that additional wear protection elements can be omitted at those uppermost and lowermost surfaces.

[0006] Compared to current rotors protected by machined top and bottom wear plates, by manufacturing the rotor as a wear part, a less challenging manufacturing process is achieved, since less machining is needed. Since the amount of wear parts and the amount of mating surfaces between parts is reduced, less machining is needed. As in current rotors, a large amount of wear parts and mating surfaces need to be manufactured precisely, but when manufacturing the rotor as a wear part, these challenges are reduced due to the reduced amount of wear parts and mating surfaces between wear parts. Another advantage of having fewer parts is that production costs are reduced. Yet another advantage of having fewer parts is that assembly work is also reduced.

[0007] The disclosed rotor is balanced at the factory, after which the customer no longer needs to balance it. Therefore, no turning of the rotor is needed. Furthermore, no replacement of parts of the rotor is needed when the rotor is worn out, but instead the entire rotor is replaced after the rotor is worn out. Therefore, a more straightforward wear part replacement procedure is achieved, which provides a reduction in time spent on maintenance. Therefore, another advantage of the rotor of the present disclosure is that maintenance operations or repairs at the customer side are largely reduced.

[0008] Yet another advantage of the rotor of the present disclosure is that the material weight is reduced due to the reduced number of parts. By reducing the weight of the rotor, lighter weight lifting is needed, which provides a safer design in terms of maintenance and installation. Furthermore, the fact that the rotor is easier to replace when worn out means that less time is spent, which in turn reduces production downtime.

[0009] Compared to current rotors equipped with machined top and bottom wear plates screwed to a less hard rotor body, yet another advantage of the rotor, wherein the uppermost surface of the frame and the lowermost surface of the frame have a greater hardness than the rest of the frame, is that a more stable rotor is achieved.

[0010] It should be noted that the cost of the old wear plates is more or less the same as the cost of the entire disclosed rotor. Due to the reduced manufacturing time and maintenance operation time and the reduced number of material parts needed, the cost is reduced compared to a traditional rotor.

[0011] Thus, the rotor is advantageous over the prior art in that it allows for a reduction in the amount of wear parts and mating surfaces between these parts. This in turn facilitates balancing and reduces vibrations of the rotor, resulting in a reduced weight of the rotor as well as reduced costs and manufacturing time.

[0012] According to some embodiments, the frame is provided in the form of a weldment.

[0013] This is advantageous in that the manufacturing process can be easier and manufacturing time is reduced. Thus, in the disclosed rotor only one weldment is needed compared to current rotors where separate weldments are needed and the bottom and top wear plates are bolted together with the rotor body. Another advantage of the disclosed rotor (where the frame is provided in the form of a weldment) is that no top and bottom wear plate assembly time and no rotor and bolted plate adjustment time is needed. Thus, the assembly time is greatly reduced.

[0014] According to some embodiments, the frame is balanced around its intended axis of rotation.

[0015] This is advantageous in that it allows the frame to already be balanced in the correct way during the manufacturing process. As mentioned above, this balancing process is performed at the factory and the customer does not need to balance the frame. Thus, the customer's maintenance time is reduced.

[0016] According to some embodiments, the upper and lower plates have a greater hardness than the wall elements.

[0017] According to some embodiments, the ratio of the hardness of at least one of the upper and lower plates to the hardness of at least one of the wall elements is in the range of 1.3 to 5.3.

[0018] According to some embodiments, the ratio of the hardness of at least one of the upper and lower plates to the hardness of at least one of the wall elements is in the range of 2.5 to 3.

[0019] This is advantageous in that it is typically the upper and lower plates that are exposed to more wear compared to the wall elements. Thus, an increase in rotor lifetime is achieved.

[0020] In preferred embodiments, the hardness of the upper and lower plates is between 270-530 HB. In preferred embodiments, the hardness of the wall element(s) is between 100-190 HB. In one embodiment, the upper and lower plates have the same hardness. In other embodiments, the hardness between the two plates can be different. In one embodiment, the separate wall elements have the same hardness. In other embodiments, the hardness between the wall elements can be different.

[0021] According to some embodiments, wherein the ratio of the tensile strength of at least one of the upper plate and the lower plate to the tensile strength of at least one of the wall elements is in the range of 1.5 to 3.8.

[0022] According to some embodiments, wherein the ratio of the tensile strength of at least one of the upper plate and the lower plate to the tensile strength of at least one of the wall elements is in the range of 2.2 to 2.6.

[0023] In preferred embodiments, the tensile strength of the upper plate and the lower plate is between 1000-1400 MPa. In preferred embodiments, the tensile strength of the wall element(s) is between 370-630 MPa.

[0024] In preferred embodiments, the yield strength of the upper plate and the lower plate is between 900-1200 MPa. In preferred embodiments, the yield strength of the wall element(s) is between 235-355 MPa.

[0025] According to some embodiments, the frame is configured to receive at its exposed area a replaceable wear protection element.

[0026] The term "exposed area" here refers to any area in the rotor that is exposed to wear when the rotor is in operation.

[0027] According to some embodiments, the replaceable wear protection element is weight matched to reduce imbalance.

[0028] This is advantageous as it enables the operator to replace the replaceable wear protection element in the field after it has been received by the rotor without the need to balance the rotor.

[0029] According to some embodiments, the replaceable wear protection element comprises one or more of: a cavity wear plate arranged at the lower plate, a tailgate, a rotor tip, a distribution plate.

[0030] According to some embodiments, the replaceable wear protection element comprises a cavity wear plate.

[0031] The term "replaceable wear protection element" here refers to that the wear protection element can be removed and replaced in an easy manner after wear. Thus, instead of replacing the rotor itself, the wear protection element can be replaced.

[0032] This is advantageous as it allows for an increased lifetime of the rotor. The wear protection elements are arranged inside the rotor, e.g. the tips, the cavity wear plate, the upper wear plate and the lower wear plate. The lifetime differs between the different wear parts, but the lifetime of the different wear parts is less compared to the lifetime of the frame. Thus, by enabling the wear protection elements to be replaceable, the wear protection elements provide for an increased lifetime of the rotor.

[0033] It should be noted that the exchangeable wear part of the current rotor is preferably also suitable for the disclosed rotor.

[0034] According to some embodiments, the circumference of the upper plate and the lower plate has a substantially circular shape.

[0035] According to some embodiments, the upper plate and the lower plate have a local recess deviating from a circular shape.

[0036] This is advantageous as it allows for controlling the rotor performance. Thus, the shape of the upper plate and the lower plate has an influence on the rotor performance. Thus, different shapes of the upper plate and the lower plate enable different rotor performances. Thus, the shape of the upper plate and the lower plate is arranged for controlling the material fed to the rotor.

[0037] An advantage of the rotor of the present disclosure, wherein the upper plate and the lower plate have a local recess deviating from a circular shape, is that the overall weight of the upper plate and / or the lower plate is reduced, such that the plates can be more user friendly.

[0038] According to a second aspect, there is provided a method for manufacturing a rotor for a comminution device, the rotor being arranged to emit material to be comminuted towards a surface, such as an anvil or a self-generated layer of broken material, the method comprising the steps of:

[0039] providing the rotor with an upper plate, a lower plate and a wall element having an inlet opening therein;

[0040] connecting the wall element such that it extends between the upper plate and the lower plate and such that one or more outlets are formed between the upper plate and the lower plate,

[0041] wherein the uppermost surface of the upper plate and the lowermost surface of the lower plate have a greater hardness than the rest of the rotor, such that additional wear protection elements can be omitted at those surfaces.

[0042] According to a third aspect, there is provided a comminution device comprising a rotor according to the first aspect.

[0043] The effects and features of the second and third aspects are largely analogous to the effects and features described above in connection with the first aspect. The embodiments mentioned in relation to the first aspect are largely compatible with the second and third aspects. It should also be noted that the inventive concept relates to all possible combinations of the features unless otherwise explicitly stated.

[0044] Further scope of the applicability of the present application will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the application, are given by way of illustration only, since various changes and modifications within the scope of the application will become apparent to those skilled in the art from this detailed description.

[0045] It should be understood, therefore, that the present application is not limited to the particular combinations of components described or the steps of the methods described, as such devices and methods can vary. It should be further understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in the specification and the appended claims, the articles "a," "an," "the," and "said” are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" can include several devices, and the like. Additionally, the words "comprising," "containing," "including," and similar wordings do not exclude other elements or steps. BRIEF DESCRIPTION OF DRAWINGS

[0046] The present application will be described in greater detail by reference to the following drawings, wherein the presently preferred embodiments of the application are shown:

[0047] Figure 1 A perspective view of a comminution apparatus is shown.

[0048] Figure 2 A perspective view of a comminution apparatus according to an embodiment of the present disclosure is shown. Figure 1 An interior of the comminution apparatus of

[0049] Figure 3 A more detailed view of the rotor of Figure 2

[0050] Figure 4 An interior of the rotor of Figure 2 and Figure 3 DETAILED DESCRIPTION

[0051] The present application will now be described more fully hereinafter with reference to the accompanying drawings, in which current preferred embodiments of the application are shown. The application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of illustration of the application and its best mode contemplated for practical clinical purposes. As used herein, the term "comprises" or "comprising" or the like means including but not limited to, and should not be interpreted as being restricted or limited to meaning "consists only of.

[0052] Figure 1 ​​A comminution apparatus 100 for crushing or grinding rock, ore, cement clinker and other hard materials is shown by way of example. The comminution apparatus 100 is configured to comminute material by forcing the material against metal with force, but also by using the material fed into the comminution apparatus 100 to comminute itself. The comminution apparatus 100 can be a vertical shaft impact crusher. Reference will be made to Figure 2 The crushing process of the comminution apparatus 100 is discussed in more detail.

[0053] The comminution apparatus 100 comprises a top portion 102 and a chamber 104. The chamber 104 is arranged on a base portion 106 of the comminution apparatus 100. The top portion 102 is arranged on top of the chamber 104.

[0054] The comminution apparatus 100 further comprises a hopper 216 (see Figure 2 By way of example, the hopper 216 is illustrated in Fig. 2. The hopper 216 is arranged within the top portion 102. The hopper 216 can comprise an opening arranged centrally in an upper portion of the hopper 216. The hopper 216 can be configured to receive material 216 to be crushed through the centrally arranged opening. The hopper 216 is further configured to feed the material 204 to the chamber 104.

[0055] The comminution apparatus 100 further comprises a rotor 108. The rotor 108 is arranged within the chamber 102. The rotor 108 is configured to crush material received in the chamber 102. Thus, the rotor is the main working component of the comminution apparatus 100. Reference will be made to Figures 2-4 The rotor 108 is discussed in further detail.

[0056] With reference to Figure 2 Fig. 2, the interior 200 of the comminution apparatus 100 is shown by way of example. In addition to what has already been discussed in connection with Figure 1 The comminution apparatus 100 comprises a control gate 220. The control gate 220 can be arranged at a bottom end of the hopper 216. The control gate 220 is configured to change the cascade ratio. Thus, the control gate 220 is configured to control the amount of material 214 fed from the hopper 216 towards the rotor 108.

[0057] Furthermore, the rotor 108 comprises a frame 202. The frame 202 comprises an upper plate 204, a lower plate 206 and wall elements 208. The frame 202 is provided in the form of a weldment. The wall elements 208 extend between the upper plate 204 and the lower plate 206 and are perpendicular to the upper plate 204 and the lower plate 206. In other words, the rotor 108 is manufactured by providing the rotor 108 with an upper plate 204, a lower plate 206 and wall elements 208. The wall elements 208 can be connected such that they can extend between the upper plate 204 and the lower plate 206. The rotor 108 further comprises an inlet opening 210 and an outlet 212. The inlet opening 210 is arranged in the upper plate 204. The outlet 212 is located between the upper plate 204 and the lower plate 206. The rotor 108 can comprise more than one outlet 212. In combination Figures 3-4 The rotor 108 is shown in more detail.

[0058] During operation of the crushing plant 100, the rotor 108 is configured to rotate. The rotor 108 is configured to rotate around an axis of rotation A. The axis of rotation is a vertical axis. Preferably, the rotor 108 rotates at 1800-3000 revolutions per minute (RPM) and the rotor tip speed can be up to 75 m / s. The maximum weight of the rotor 108 can be about 900-950 kg. Thus, with the heavy weight and the rather high speed, the rotor 108 needs to be balanced in the right way in order to perform the crushing process in the right way. The rotor 108 is balanced at the factory where the rotor 108 is produced. The frame 202, which is a weldment, makes it so that the rotor 108 only needs to be balanced at the factory and the customer does not need to balance or adjust the rotor 108 on site. The rotor 108 can be balanced around its intended axis of rotation A.

[0059] During operation, the material 214 received by the rotor 108 is pushed away from the rotor 108 by the outlet 212 towards a surface 218. The surface 218 is arranged in the chamber 104. In other words, the rotor 108 is configured to emit the material 214 to be crushed towards the surface 218 within the chamber 104. The surface 218 can be an anvil. The surface 106 can comprise an accumulation of material to be broken, i.e. a self-generated layer of broken material. The accumulation in the crushing plant 100 is a retained material which forms the surface 218 over which the feed material slides. It can form the shape of a wave with the wave crests towards the centre of the rotor 108. This accumulation can also be arranged in the rotor 108. The accumulation in the rotor 108 is needed to protect the inner walls of the rotor 108 and, most importantly, to protect the rotor tips from direct wear and impact. The accumulation can vary with material properties, rotor speed, feed rate, feed size and moisture content. This can provide a crushing chamber that generates self-generated breaking. Such self-generated breaking has proven to guarantee excellent shaped particles, e.g. aggregates. Preferably, the final product leaving the crusher 104 has a particle size of about 55 mm.

[0060] Reference is made to Figure 3 The rotor 108 is shown in more detail by way of example. As discussed in connection with Figure 2 The rotor 108 comprises a frame 202 provided in the form of a weldment. The frame 202 comprises an upper plate 204, a lower plate 206 and a wall element 208.

[0061] The upper plate 204 can have a circumference having a substantially circular shape. The lower plate 206 can have a circumference which can have a substantially circular shape. As Figure 3 The upper plate 204 and the lower plate 206 can have a local recess 302. The local recess 302 can deviate from the circular shape. With the arrangement in which the upper plate 204 and / or the lower plate 206 can have a local recess 302, a reduction of the weight of the respective plate 204, 206 is provided compared to a conventional rotor. This can be advantageous as it improves the manufacturing as well as the maintenance operations of the rotor 108.

[0062] The upper plate 204 and the lower plate 206 can have a greater hardness than the wall element 208. The ratio of the hardness of at least one of the upper plate 204 and the lower plate 206 to the hardness of at least one of the wall element 208 can be in the range of 1.3 to 5.3. The ratio of the hardness of at least one of the upper plate 204 and the lower plate 206 to the hardness of at least one of the wall element 208 can be in the range of 2.5 to 3. The ratio of the tensile strength of at least one of the upper plate 204 and the lower plate 206 to the tensile strength of at least one of the wall element 208 can be in the range of 1.5 to 3.8. The ratio of the tensile strength of at least one of the upper plate 204 and the lower plate 206 to the tensile strength of at least one of the wall element 208 can be in the range of 2.2 to 2.6.

[0063] The rotor 108 can further comprise an uppermost surface 304 of the frame 202 and a lowermost surface 306 of the frame 202. The uppermost surface 304 is arranged on the upper plate 204. The lowermost surface 306 is arranged on the lower plate 206. The uppermost surface 304 and the lowermost surface 306 have a greater hardness than the rest of the frame 202. An advantage when the uppermost surface 304 and the lowermost surface 306 have a greater hardness than the rest of the frame 202 is that additional wear protection elements can be omitted at those uppermost surface 304 and lowermost surface 306.

[0064] Reference is made to Figure 4 The interior of the rotor 108 is shown by way of example. The frame 202 is further configured to receive exchangeable wear protection elements at its exposed areas. The exchangeable wear protection elements can be weight matched to reduce unbalance. Preferably, the exchangeable wear protection elements are weight matched within 5-10 grams.

[0065] The replaceable wear protection element can include a cavity wear plate 402. The replaceable wear protection element can include a rotor tip 404.

[0066] The replaceable wear protection element can include a distribution plate 206 arranged at the lower plate 206 downstream of the inlet opening 210 such that one or more outlets 212 can be formed between the upper plate 204 and the lower plate 206. The distribution plate 406 is arranged on the upper surface of the lower plate 206. Preferably, the distribution plate 406 is a rotating distribution plate and when material to be crushed hits the rotating distribution plate 406, the material will be dragged generally radially outward through the outlets 212 and hit the surface 218 as discussed in connection with Figure 2 The distribution plate 406 can be designed differently depending on the material to be crushed.

[0067] The replaceable wear protection element can include a lower wear plate 408.

[0068] The replaceable wear protection element can include a tail plate 410. The arrangement of the tail plate 410 can control the material build-up. A wide tail plate 410 causes the material to build up deeper. A narrow tail plate 410 causes the material to build up shallower. Moving the tail plate 410 away from the rotor tip 404 causes the build-up to be shallower. Moving the tail plate 410 towards the rotor tip 404 causes the material to build up deeper. The angle of the tail plate 410 can control the build-up depth at the top and bottom of the rotor 108. An angled tail plate 410 (a tail plate 410 with a wide base and a narrow top) can direct more material to the top of the rotor 108, increasing the wear path on the rotor tip 404 and decreasing the gap around the feed pipe. A straight tail plate 410 can tend to direct material to the bottom of the rotor tip 404 and increase the gap around the feed pipe.

[0069] It will therefore be appreciated that it is an object of the present disclosure to reduce the problem of rotor 108 balancing and rotor 108 vibration while the pulverizing apparatus 100 is in operation. It is a further object to reduce the machining required during the manufacturing process, thereby also reducing the manufacturing challenges.

[0070] The person skilled in the art realizes that the present invention is in no way limited to the preferred embodiments described above. On the contrary, many modifications and changes are possible without departing from the scope of the appended claims. In addition, variants of the disclosed embodiments can be understood and implemented by a person skilled in the art in the practice of the claimed invention by studying the attached drawings, the disclosure and the appended claims.

Claims

1. A rotor (108) for a comminution apparatus (100), the rotor (108) being arranged to emit material (214) to be comminuted towards a surface (218), the rotor (108) comprising a frame (202), the frame (202) comprising an upper plate (204), a lower plate (206) and a wall element (208) extending between the upper plate (204) and the lower plate (206), the rotor (108) further comprising an inlet opening (210) in the upper plate (204) and an outlet (212) between the upper plate (204) and the lower plate (206), wherein, The upper plate (204) and the lower plate (206) have a greater hardness than the wall elements (208), such that the uppermost surface (304) of the frame (202) and the lowermost surface (306) of the frame (202) have a greater hardness than the rest of the frame (202), such that additional wear protection elements can be omitted at the uppermost and lowermost surfaces (304, 306).

2. The rotor (108) of claim 1, wherein, The frame (202) is provided in the form of a weldment.

3. The rotor (108) of claim 1, wherein, The frame (202) is balanced around its intended axis of rotation (A).

4. The rotor (108) of claim 2, wherein, The frame (202) is balanced around its intended axis of rotation (A).

5. The rotor (108) according to any one of claims 1 to 4, wherein The ratio of the hardness of at least one of the upper plate (204) and the lower plate (206) to the hardness of at least one of the wall elements (208) is in the range of 1.3 to 5.

3.

6. The rotor (108) according to any one of claims 1 to 4, wherein The ratio of the hardness of at least one of the upper plate (204) and the lower plate (206) to the hardness of at least one of the wall elements (208) is in the range of 2.5 to 3.

7. The rotor (108) according to any one of claims 1 to 4, wherein The ratio of the tensile strength of at least one of the upper plate (204) and the lower plate (206) to the tensile strength of at least one of the wall elements (208) is in the range of 1.5 to 3.

8.

8. The rotor (108) according to any one of claims 1 to 4, wherein The ratio of the tensile strength of at least one of the upper plate (204) and the lower plate (206) to the tensile strength of at least one of the wall elements (208) is in the range of 2.2 to 2.

6.

9. The rotor (108) according to any one of claims 1 to 4, wherein The frame (202) is configured to receive exchangeable wear protection elements at its exposed areas.

10. The rotor (108) of claim 9, wherein, The exchangeable wear protection elements are weight-matched to reduce imbalance.

11. The rotor (108) of claim 9, wherein, The exchangeable wear protection elements comprise one or more of: a cavity wear plate (402) arranged at the lower plate (206) downstream of the inlet opening (210), a tail plate (410), a rotor tip (404), a distribution plate (406).

12. The rotor (108) of claim 10, wherein, The exchangeable wear protection elements comprise one or more of: a cavity wear plate (402) arranged at the lower plate (206) downstream of the inlet opening (210), a tail plate (410), a rotor tip (404), a distribution plate (406).

13. The rotor (108) of claim 1, wherein, The circumference of the upper plate (204) and the lower plate (206) has a substantially circular shape.

14. The rotor (108) of claim 13, wherein, The upper plate (204) and the lower plate (206) have a local recess (302) deviating from the circular shape.

15. Method for manufacturing a rotor (108) of a comminution device (100), the rotor (108) being arranged to emit material (214) to be comminuted towards a surface (218), the method comprising the steps of: - providing the rotor (108) with an upper plate (204), a lower plate (206) and a plurality of wall elements (208) having an inlet opening (210) therein; - connecting the wall elements (208) such that they extend between the upper plate (204) and the lower plate (206) and such that one or more outlets (212) are formed between the upper plate (204) and the lower plate (206), - connecting the wall elements (208) such that they extend between the upper plate (204) and the lower plate (206) and such that one or more outlets (212) are formed between the upper plate (204) and the lower plate (206), wherein the upper plate (204) and the lower plate (206) have a greater hardness than the wall element (208) such that the uppermost surface (304) of the upper plate (204) and the lowermost surface (306) of the lower plate (206) have a greater hardness than the rest of the rotor (108) such that additional wear protection elements can be omitted at the surfaces (304, 306).

16. Milling device (100) comprising a rotor (108) according to any one of claims 1 to 14.

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