Descaler

Abstract

Descaling device (1) with a device housing (2), a shaft (3), a shaft bearing (4), a nozzle head (5), a medium coupling (6) and a motor (32), wherein the shaft bearing (4) is arranged in the device housing (2) and the shaft (3) is supported by the shaft bearing (4) in the device housing (2) to perform a rotary movement (12), wherein the shaft (3) and the nozzle head (5) are connected to each other in a non-destructively detachable manner, wherein the medium coupling (6) has a medium connection (20) for supplying a medium (21), wherein the shaft (3) has a shaft cavity (22) for guiding the medium (21) fed in at the medium connection (20) to the nozzle head (5), wherein the motor (32) for generating the rotary motion (12) of the shaft (3) is arranged on the shaft (3) in the device housing (2) between the nozzle head (5) and the medium coupling (6), wherein the shaft (3) has a first partial shaft (15) and a second partial shaft (16), wherein the first partial shaft (15) and the second partial shaft (16) are connected to each other in a non-destructively detachable manner, wherein the first partial shaft (15) is connected to the nozzle head (5), wherein the shaft bearing (4) is arranged exclusively on the first partial shaft (15) and wherein the medium coupling (6) is arranged on the second partial shaft (16), characterized by that the first partial shaft (15) and the second partial shaft (16) each have a blind hole (23) with an open end and a closed end and that the blind hole (23) of the first partial shaft (15) and the blind hole (23) of the second partial shaft (16) together form the shaft cavity (22).

Description

[0001] The invention relates to a descaling device comprising a housing, a shaft, a shaft bearing, a nozzle head, and a medium coupling. The shaft bearing is arranged in the housing, and the shaft is mounted in the housing by the bearing to enable rotation. The shaft and the nozzle head are connected to each other in a non-destructive manner. The medium coupling has a medium connection for supplying a medium, and the shaft has a cavity for guiding the medium supplied at the medium connection to the nozzle head.

[0002] A scale scrubber typically consists of several such descaling devices. In addition, a scale scrubber also includes a high-pressure generating device. This device pressurizes a medium to approximately 200 to 420 bar. This medium is, for example, water. A scale scrubber is usually part of a hot forming machine, which shapes heated workpieces. The heating improves formability. Examples of such hot forming machines include hot rolling mills and forging presses. During hot forming, the temperature of a heated workpiece is often above its recrystallization temperature. The heat of the workpiece causes scale to form on its surface. Scale is an impurity consisting of iron oxide.Scale that forms immediately after a workpiece is heated is particularly stubborn compared to scale that forms later and is referred to as primary scale. Scale that is not removed from a workpiece is detrimental to that workpiece.

[0003] A medium pressurized by the high-pressure generating device is fed into a descaling device at the medium connection of the medium coupling. The medium coupling directs the fed medium from the medium connection into the shaft cavity. The shaft cavity then directs the medium to the nozzle head. The nozzle head converts the pressure into kinetic energy and ejects the medium towards the workpiece. Essentially, the kinetic energy of the medium causes the scale to be removed from the workpiece surface upon impact. The removal of scale from a surface is also known as descaling. The effectiveness of the descaling depends on the velocity of the medium, and thus on the pressure of the medium, and the distance of the nozzle head from the workpiece.Therefore, firstly, the medium is placed under the highest possible pressure, and secondly, the nozzle head is positioned as close as possible to the workpiece.

[0004] To improve the effectiveness of the descaling process, the nozzle head, together with the shaft, performs the rotary motion determined by the shaft bearing. The shaft is driven by a motor, located separately from the descaling device, via additional drive components.

[0005] A descaling device of the type described and also a descaling washer are known, for example, from patent specification DE 43 28 303 C2.

[0006] German patent application DE 10 2015 226 657 A1 describes a device for descaling a workpiece. This device comprises several nozzle assemblies, a gearbox, and at least one motor. Each nozzle assembly includes a nozzle head with at least one nozzle for spraying a fluid onto the surface of the workpiece, as well as a nozzle rotor. The nozzle rotors are connected to the at least one motor via the gearbox, with the number of nozzle assemblies being greater than the number of motors.

[0007] A device for a machine tool is known from European patent application EP 0 381 009 A2. The device comprises a spindle housing, a workpiece spindle, and a drive motor. The drive motor, in turn, comprises a rotor, a stator, a motor housing, and a motor cover. The motor housing is connected to the spindle housing. The rotor is mounted on the workpiece spindle. The stator is arranged on the motor housing. Coolant channels run between the motor housing and the motor cover, between the rotor and the workpiece spindle, and between the spindle housing and the rotor.

[0008] While a single, separately mounted motor allows for the operation of multiple descaling units, the additional drive components between the motor and the descaling unit—like the motor and the descaling unit itself—require maintenance, reduce reliability, take up installation space, complicate adaptation to applications such as hot rolling mills, and, particularly due to the arrangement of these additional drive components on the motor and descaling unit, complicate the maintenance of both. Maintenance specifically includes the detection of wear and replacement when wear reaches a certain level.

[0009] The object of the present invention is therefore to provide a descaling device of the type described, which reduces at least one of the described disadvantages.

[0010] The problem is solved by a descaling device with the features of claim 1. According to the invention, the descaling device of the described type has a motor which is arranged on the shaft in the device housing between the nozzle head and the medium coupling to generate the rotary motion of the shaft.

[0011] This motor arrangement eliminates the need for additional drive components required to transmit rotary motion from a separately mounted motor to the shaft of a descaling device. This also eliminates the maintenance of these components, increases reliability, facilitates adaptability, and simplifies maintenance of the descaling device, particularly through improved accessibility due to the absence of these additional drive components. Furthermore, the descaling device is more compact than previously known descaling devices and enables a modular design for a descaling scrubber.

[0012] The descaling device is located in close proximity to a hot workpiece within a hot forming machine. Consequently, it is also exposed to the environmental influences of the hot forming machine. These environmental influences include, in particular, high temperatures, humidity, and particles such as removed, i.e., dissolved, scale. Therefore, in one embodiment of the descaling device according to the invention, the device housing hermetically encloses the motor. This hermetic enclosure ensures that the motor itself is protected from the environmental influences. In particular, the device housing is designed such that no particles, and preferably not even the descaling medium, can penetrate it.

[0013] In a further embodiment, the motor is designed as an electric motor. An electric motor generally comprises a motor shaft, a rotor mounted on the motor shaft, a motor housing, a stator located within the motor housing, and a bearing for supporting the motor shaft within the motor housing. When electrical energy is supplied, magnetic fields act between the rotor and the stator, exerting a torque on the rotor, which the rotor then transmits to the motor shaft. In the present embodiment of the descaling device, the device housing also serves as the motor housing, the shaft also as the motor shaft, and the shaft bearing also as the motor shaft bearing. The stator is located within the device housing, and the rotor is mounted on the shaft. Thus, during operation of the descaling device, the rotational movement of the shaft is directly driven by the electric motor, without the need for any additional drive components.

[0014] Studies have shown that for effective descaling of a workpiece, advantageous nozzle head speeds lie in the range of 500 rpm to 600 rpm. If alternating current with a frequency between 50 Hz and 60 Hz is available to supply the electric motor with electrical energy, an asynchronous motor with six pole pairs is particularly suitable. The shaft of an asynchronous motor with six pole pairs rotates at 500 rpm when powered by an alternating current of 50 Hz and at 600 rpm when powered by an alternating current of 60 Hz.

[0015] In a further embodiment of the descaling device, the shaft is not made from a single workpiece, but comprises a first partial shaft and a second partial shaft, wherein the first partial shaft and the second partial shaft are connected to each other in a non-destructive manner. Preferably, the shaft consists only of the first and second partial shafts. A first component, such as the first partial shaft, and a second component, such as the second partial shaft, are connected to each other in a non-destructive manner if, after the components are separated, they remain unchanged compared to their connected state. This also implies, in particular, that reconnecting the components is readily possible. A non-destructively detachable connection between the first and second partial shafts is, for example,This is achieved by a thread in the first partial shaft along a longitudinal axis of the first partial shaft and a complementary thread in the second partial shaft along a longitudinal axis of the second partial shaft. Thus, the first and second partial shafts can be easily and non-destructively connected by screwing them together and easily and non-destructively disconnected by loosening the screw connection. A sealing device is preferably also provided in the connection between the first and second partial shafts. This sealing device is, for example, at least one annular seal.

[0016] Furthermore, this embodiment provides that the first shaft section is connected to the nozzle head, the shaft bearing is located exclusively on the first shaft section, and the medium coupling is located on the second shaft section. The medium coupling is located on the shaft, specifically on the second shaft section, thus creating a contact surface between the shaft and the medium coupling. Due to the rotational movement of the shaft within the medium coupling, both the shaft and the medium coupling wear at this contact surface. In this embodiment, when the wear on the shaft at the contact surface reaches a critical level, it is no longer necessary to replace the entire shaft, but only the second shaft section, without having to involve the shaft bearing.

[0017] In a further development of the above embodiment, the first and second shaft sections each have a blind hole with an open end and a closed end. The blind hole of the first shaft section and the blind hole of the second shaft section together form the shaft cavity. Accordingly, the closed end of the first shaft section is located at the nozzle head and the closed end of the second shaft section is located at the medium coupling. Thus, the shaft is sealed at its ends by the closed ends of the blind holes. In descaling devices known from the prior art, at least one end of the shaft is often sealed with a screw.However, sealing one end of a shaft with a screw is disadvantageous because, during the operation of a descaling device, the injected medium exhibits strong pressure fluctuations, which exert a pulsating force on the screw in the longitudinal direction, causing the screw to loosen and allowing the medium to escape from the end of the shaft.

[0018] In a further embodiment of the descaling device, the medium coupling comprises a coupling housing, a cover, and a sealing device. The coupling housing has a coupling cavity, and the cover, which is non-destructively detachable, closes the coupling cavity. The non-destructively detachable connection between the cover and the coupling housing is implemented, for example, by a screw connection with at least one screw, the thread for which is formed in the coupling housing. To remove the cover, the at least one screw is unscrewed from the thread, and to install it, the at least one screw is screwed back into the thread. The sealing device is integrated into the coupling cavity to seal between the shaft and the medium connection. The sealing device thus ensures that a medium fed in at the medium connection is directed into the shaft cavity and...B. does not leak between the shaft and the coupling housing. Furthermore, the medium coupling and the shaft are designed such that the sealing device can be removed and inserted when the cover is disassembled. This means that the sealing device can be pulled out of the shaft cavity and pushed into the shaft cavity, and conversely, it can be removed from the shaft and slid onto the shaft. The design of the medium coupling relates in particular to the coupling housing and the sealing device. The design of the medium coupling and the shaft is such, for example, that both the coupling cavity and the shaft each have the shape of a vertical circular cylinder, and the sealing device is bounded by the outer shape of a hollow cylinder that is adapted to the coupling cavity and to the shaft within the coupling cavity. Preferably, the sealing device consists of several sealing elements.This design therefore allows for easy removal and insertion of the sealing device.

[0019] In this design, the previously described contact surface between the shaft and the medium coupling is located between the shaft and the sealing device belonging to the medium coupling. Due to the rotational movement of the shaft within the sealing device, both the shaft and the sealing device wear down at the contact surface. In this design, the sealing device can be easily inspected after simple removal from the coupling housing. Furthermore, if the wear on the sealing device at the contact surface reaches a critical level, it can also be easily replaced.

[0020] In a further development of the previously described embodiment of the descaling device, the coupling housing is separate from the device housing, and the coupling housing and the device housing are connected to each other in a non-destructively detachable manner. The non-destructively detachable connection between the coupling housing and the device housing is implemented, for example, by a screw connection with at least one screw, the thread for which is formed in the device housing. To disassemble the coupling housing, the at least one screw is unscrewed, and to assemble it, the at least one screw is screwed in. This further development allows the coupling housing to be disassembled from the device housing, after which the part of the shaft containing the contact surface is freely accessible. This advantageously allows for inspection of the shaft's contact surface.

[0021] If the shaft comprises a first partial shaft and a second partial shaft, and the medium coupling is arranged on the second partial shaft, then a preferred embodiment of the previously described embodiment is provided by designing and arranging the coupling housing on the device housing such that, with the coupling housing removed, the second partial shaft can be removed from the first partial shaft and mounted onto the first partial shaft. The second partial shaft is removable from the first partial shaft if the connection between the second partial shaft and the first partial shaft can be both disconnected and connected when the coupling housing is removed. In this embodiment, the contact surface on the shaft can be advantageously inspected, and, if the wear on the shaft's contact surface reaches a critical level, the shaft can also be advantageously replaced.

[0022] During operation of the descaling device, a warm workpiece is positioned in front of the nozzle head, and the motor is running, generating the rotary motion of the shaft. The heat generated by the motor during operation, and especially the radiant heat from the workpiece, must be dissipated to prevent the descaling device from overheating. Therefore, one embodiment of the descaling device incorporates cooling channels in the device housing. Furthermore, the housing is designed to transfer the heat from the motor and / or radiant heat from the workpiece, particularly in front of the nozzle head, to a medium present in the cooling channels. Specifically, cooling channels are formed in the part of the device housing closest to the warm workpiece.Alternatively or additionally, a further embodiment provides for the motor itself to transfer the heat generated during operation to a medium present in the shaft cavity. This design is achieved, for example, when the motor's thermal conductivity is sufficiently high to ensure adequate heat transfer to the medium. This is often the case with electric motors.

[0023] To achieve maximum descaling effectiveness, the nozzle head of the descaling device is positioned as close as possible to the workpiece and ejects a descaling medium onto the scale-covered surface. This causes the scale to be blasted off the workpiece surface and also strike the nozzle head, which is subject to wear from the impact of the scale. Therefore, in a further embodiment, the nozzle head comprises a nozzle head carrier and a nozzle support. The nozzle support contains at least one nozzle for ejecting the medium, and the nozzle head carrier has at least one channel for guiding the medium from the shaft cavity to the at least one nozzle. Furthermore, the nozzle support and the nozzle head carrier are connected to each other in a non-destructively detachable manner, and the nozzle head carrier and the shaft are connected to each other.Accordingly, the nozzle holder is positioned in front of the nozzle head carrier relative to the workpiece, and the nozzle holder is subject to wear from the scale. The non-destructive connection between the nozzle head and the nozzle head carrier is implemented, for example, by a screw connection with at least one screw, the thread for which is formed in the nozzle head carrier. To remove the nozzle head, the at least one screw is unscrewed, and to install it, the at least one screw is screwed in. With this embodiment, it is no longer necessary to replace the entire nozzle head when a critical level of wear is reached; replacing only the nozzle carrier is sufficient.

[0024] In detail, there are numerous possibilities for designing and further developing the descaling device. Reference is made to both the claims subordinate to claim 1 and to the following description of a preferred embodiment in conjunction with the drawing. The drawing shows Fig. 1 An embodiment of a descaling device in a first perspective view, Fig. 2 the embodiment in a second perspective view and Fig. 3 the embodiment in a longitudinal section.

[0025] Fig. Figure 1 shows in a first perspective view an embodiment of a descaling device 1. Fig. Figure 2 shows the embodiment in a second perspective view and Fig. Figure 3 shows the embodiment in a longitudinal section.

[0026] The descaling device 1 comprises a device housing 2, a shaft 3, a shaft bearing 4, a nozzle head 5 and a medium coupling 6.

[0027] The device housing 2 comprises a housing center segment 7, a first housing end segment 8, and a second housing end segment 9. The housing center segment 7 is hollow cylindrical, while the first housing end segment 8 and the second housing end segment 9 are plate-shaped. The housing center segment 7 is connected to the first housing end segment 8 and the second housing end segment 9, respectively, by four screw connections 10 each. Each screw connection 10 comprises a screw and a threaded insert. Thus, the screw connections 10 can be loosened and reconnected without damage. The eight threads are formed in the housing center segment 7. The housing center segment 7, the first housing end segment 8, and the second housing end segment 9 together form a housing interior 11.

[0028] The shaft bearing 4 is arranged in the device housing 2, and the shaft 3 is supported in the device housing 2 by the shaft bearing 4 to execute a rotary movement 12. The shaft bearing 4 comprises a first bearing 13, which is arranged in the first housing end segment 8, and a second bearing 14, which is arranged in the second housing end segment 9.

[0029] The shaft 3 consists of a first partial shaft 15 and a second partial shaft 16. The first partial shaft 15 and the second partial shaft 16 are connected to each other in a non-destructive manner. The non-destructively detachable and reconnectable connection between the first partial shaft 15 and the second partial shaft 16 is implemented by a first partial shaft thread 17 in the first partial shaft 15 along a longitudinal axis of the first partial shaft 15 and a second partial shaft thread 18 in the second partial shaft 16, complementary to the first partial shaft thread 17, along a longitudinal axis of the second partial shaft 16. A partial shaft seal 19 is arranged between the first partial shaft 15 and the second partial shaft 16 for sealing. The partial shaft seal 19 comprises two annular seals. The shaft 3 is connected to the nozzle head 5 via the first partial shaft 15 in a non-destructive manner.Furthermore, the shaft bearing 4 is arranged exclusively on the first partial shaft 15, and the medium coupling 6 is arranged exclusively on the second partial shaft 16. The medium coupling 6 has a medium connection 20 for supplying a medium 21.

[0030] The shaft 3 has a shaft cavity 22 for conveying the medium 21, which is fed in at the medium connection 20, to the nozzle head 5. The first partial shaft 15 and the second partial shaft 16 each have a blind hole 23 with an open end and a closed end. The blind hole 23 of the first partial shaft 15 and the blind hole 23 of the second partial shaft 16 together form the shaft cavity 22.

[0031] The nozzle head 5 comprises a nozzle head carrier 24 and a nozzle carrier 25. Eight nozzles 26 for ejecting the medium 21 are arranged in the nozzle carrier 25. The spray pattern of the ejected medium 21 is fan-shaped. Eight channels 27 are formed in the nozzle head carrier 24 for guiding the medium 21 from the shaft cavity 22 to the eight nozzles 26. The nozzle carrier 25 and the nozzle head carrier 24 are connected to each other in a non-destructive manner. The connection is made by eight screw connections 10, the corresponding threads being formed in the nozzle head carrier 24. The nozzle head carrier 24 and the shaft 3, in the form of the first partial shaft 15, are also connected to each other in a non-destructive manner. Here, the connection is made by a screw connection 10, the corresponding thread being formed in the first partial shaft 15.

[0032] The medium coupling 6 comprises a coupling housing 28, a cover 29, and a sealing device 30. The coupling housing 28 further comprises a coupling cavity 31, which is closed by the cover 29, which is connected to the coupling housing 28 in a non-destructively detachable manner. The connection of the cover 29 to the coupling housing 28 is effected by four screw connections, the corresponding threads being formed in the coupling housing 28. The sealing device 30 is integrated into the coupling cavity 31 to seal between the shaft 3, in the form of the second partial shaft 16, and the medium connection 20. The medium coupling 6 and the shaft 3, in the form of the second partial shaft 16, are designed such that the sealing device 30 can be removed and inserted when the cover 29 is disassembled.The design of the medium coupling 6 and the second partial shaft 16 is such that both the coupling cavity 31 and the second partial shaft 16 each have the shape of a vertical circular cylinder, and the sealing device 30 is bounded by the outer shape of a hollow cylinder that is adapted to the coupling cavity 31 and to the second partial shaft 16 within the coupling cavity 31. The sealing device 30 consists of several sealing elements.

[0033] The coupling housing 28 is separate from the device housing 2, and the coupling housing 2 and the device housing 2 are connected to each other in a non-destructively detachable manner. The connection is made by four screw connections, the corresponding threads being formed in the second housing end segment 9. The coupling housing 28 is designed and arranged on the device housing 2 such that, when the coupling housing 28 is removed, the second partial shaft 16 can be removed from the first partial shaft 15 and mounted on the first partial shaft 15.

[0034] The descaling device 1 comprises a motor 32 designed as an electric motor. During operation of the descaling device 1, the motor 32 generates the rotary motion of the shaft 3 and is arranged on the shaft 3 within the housing 11 of the device housing 2, between the nozzle head 5 and the medium coupling 6. Specifically, the motor 32 is also located between the first bearing 13 and the second bearing 14. The device housing 2 hermetically encloses the motor 32. The motor 32 has a rotor 33 and a stator 34. The rotor 33 is arranged on the shaft 3 in the form of the first partial shaft 15, and the stator 34 is located within the housing 11 on the device housing 2. The motor 32, designed as an electric motor, is an asynchronous motor with six pole pairs.

[0035] Cooling channels 35 are formed in the device housing 2. Furthermore, the device housing 2 is designed to transfer heat generated during operation by the motor 32 and radiant heat from a warm workpiece located in front of the nozzle head 5 to a medium present in the cooling channels 35. Therefore, cooling channels 35 are also formed in the part of the device housing 2, namely the first housing end segment 8, which is closest to the warm workpiece. The medium present in the cooling channels is, for example, the medium 21, which is used for descaling. Reference sign 1 descaling device 2 device housings 3rd wave 4 shaft bearings 5 nozzle heads 6 Medium coupling 7 Housing center segment 8 First housing end segment 9 Second housing end segment 10 screw connections 11 Interior of the housing 12 Rotational movement 13 First Camp 14 Second Camp 15 First partial wave 16 Second partial wave 17 First partial shaft thread 18 Second partial shaft thread 19 partial shaft seals 20 Medium connection 21 Medium 22 wave cavity 23 Blind Hole 24 nozzle head carriers 25 nozzle carriers 26 nozzle Channel 27 28 clutch housings 29 lids 30 Sealing device 31 Clutch cavity 32 engine 33 Rotor 34 Stator 35 Cooling channel

Claims

[1] Descaling device (1) comprising a device housing (2), a shaft (3), a shaft bearing (4), a nozzle head (5), a medium coupling (6) and a motor (32), wherein the shaft bearing (4) is arranged in the device housing (2) and the shaft (3) is supported by the shaft bearing (4) in the device housing (2) to perform a rotary movement (12), wherein the shaft (3) and the nozzle head (5) are connected to each other in a non-destructively detachable manner, wherein the medium coupling (6) has a medium connection (20) for supplying a medium (21), wherein the shaft (3) has a shaft cavity (22) for guiding the medium (21) fed in at the medium connection (20) to the nozzle head (5), wherein the motor (32) for generating the rotary motion (12) of the shaft (3) is arranged on the shaft (3) in the device housing (2) between the nozzle head (5) and the medium coupling (6), wherein the shaft (3) has a first partial shaft (15) and a second partial shaft (16), wherein the first partial shaft (15) and the second partial shaft (16) are connected to each other in a non-destructively detachable manner, wherein the first partial shaft (15) is connected to the nozzle head (5), wherein the shaft bearing (4) is arranged exclusively on the first partial shaft (15) and wherein the medium coupling (6) is arranged on the second partial shaft (16), characterized by , that the first partial shaft (15) and the second partial shaft (16) each have a blind hole (23) with an open end and a closed end and that the blind hole (23) of the first partial shaft (15) and the blind hole (23) of the second partial shaft (16) together form the shaft cavity (22). [2] Descaling device (1) according to claim 1, characterized by , that the device housing (2) hermetically encloses the motor (32). [3] Descaling device (1) according to claim 1 or 2, characterized by , that the motor (32) is designed as an electric motor. [4] Descaling device (1) according to any one of claims 1 to 3, characterized by , that the medium coupling (6) has a coupling housing (28), a cover (29) and a sealing device (30), that the coupling housing (28) has a coupling cavity (31), that the cover (29) is connected to the coupling housing (28) in a non-destructively detachable manner and closes the coupling cavity (31), that the sealing device (30) is provided in the coupling cavity (31) for sealing between the shaft (3) and the medium connection (20), and that the medium coupling (6) and the shaft (3) are designed such that the sealing device (30) can be removed and inserted when the cover (29) is removed. [5] Descaling device (1) according to claim 4, characterized by, that the coupling housing (28) is separate from the device housing (2) and that the coupling housing (28) and the device housing (2) are connected to each other in a way that allows for non-destructive removal. [6] Descaling device (1) according to claim 5 and one of claims 4 or 5, characterized by , that the clutch housing (28) is designed and arranged on the device housing (2) such that, with the clutch housing (28) removed, the second partial shaft (16) can be removed from the first partial shaft (15) and mounted on the first partial shaft (15). [7] Descaling device (1) according to any one of claims 1 to 6, characterized by , that cooling channels (35) are formed in the device housing (2) and that the device housing (2) is designed to transfer heat generated during operation by the motor (32) and / or radiant heat from a workpiece to a medium present in the cooling channels (35). [8] Descaling device (1) according to any one of claims 1 to 7, characterized by , that the motor (32) is designed to transfer heat generated during operation of the motor (32) to a medium present in the shaft cavity (22). [9] Descaling device (1) according to any one of claims 1 to 8, characterized by , that the nozzle head (5) has a nozzle head carrier (24) and a nozzle carrier (25), that at least one nozzle (26) for ejecting a medium (21) is arranged in the nozzle carrier (25), that at least one channel (27) for guiding the medium (21) from the shaft cavity (22) to the at least one nozzle (26) is formed in the nozzle head carrier (24), that the nozzle carrier (25) and the nozzle head carrier (24) are connected to each other in a non-destructively detachable manner, and that the nozzle head carrier (24) and the shaft (3) are connected to each other.

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