Auxiliary device for improving operation reliability of sweeping chain of air-cooled dry type slag conveyor

Abstract

The invention discloses an auxiliary device for improving the operation reliability of a sweeping chain of an air-cooled dry type slag conveyor, which relates to the field of auxiliary devices of air-cooled dry type slag conveyors and comprises an inlet bin, a crushing bin, a conveying pipeline, an extension pipeline and a fan assembly. Fine ash is received by the inlet bin and enters the conveying pipeline after being crushed by the crushing shaft with the net-shaped hollow structure in the crushing bin. The first fan blows out rotational flow air to push ash to advance through cooperation of an outer disc, a rotating motor and the like, and the position of the conveying pipeline can be adjusted on the flat ground through a transverse guide rail and a steering wheel or by means of a foundation pit guide rail. When the conveying distance needs to be prolonged, the extension pipeline with the second fan can be clamped and connected through the rubber telescopic sleeve. Compared with the prior art, the device can improve the energy utilization efficiency, prevent ash from caking, improve the conveying efficiency, adapt to complex working conditions, reduce the equipment abrasion and fault probability and reduce environmental pollution, and can be matched with various slag conveyors to reduce the equipment updating cost.

Description

Technical Field

[0001] The invention relates to the field of auxiliary devices for air-cooled dry slag conveyors, and in particular to an auxiliary device for improving the operating reliability of a cleaning chain of an air-cooled dry slag conveyor. Background Art

[0002] Large coal-fired power generation units mostly use air-cooled dry slag conveyors, which are divided into two parts. The upper part is a steel belt conveyor for conveying blocky ash slag, and the lower part is a cleaning chain for conveying fine ash slag dropped by the steel belt conveyor. Both the steel belt conveyor and the cleaning chain use variable frequency motors. Under the condition of burning the designed coal type, the cleaning chain can run intermittently. However, in recent years, affected by the market coal supply situation and changes in their own business situation, the quality of coal entering the furnace of most coal-fired units has seriously deviated from the requirements of the designed coal type, and the ash content of the coal is significantly higher than the design value, which has led to a significant increase in the amount of ash dropped by the cleaning chain, far exceeding its designed output. A large amount of fine ash slag accumulates in the cleaning chain box and cannot be discharged in time, resulting in frequent faults and tripping of the cleaning chain. It is necessary to manually clean the internal ash slag and reset the cleaning chain before it can be re-operated. During the cleaning period, the unit's slag conveying system must be completely shut down, which not only brings great difficulties to daily inspection and maintenance, but also seriously affects the safe and stable operation of the slag conveying system.

[0003] After consulting with manufacturers and on-site transformation, it is known that simply increasing the speed of the cleaning chain and increasing the number of scrapers cannot substantially increase the system output. Therefore, it is necessary to increase the fine ash handling capacity by adding an auxiliary conveying system, otherwise the system will not be able to operate normally. In addition, due to the accumulation of a large amount of fine ash, the cleaning chain frequently fails and trips. Each failure requires manual cleaning of the internal ash and resetting the cleaning chain before it can be re-operated. During the cleaning period, the unit's slag conveying system must be completely shut down. This not only consumes a lot of manpower, material resources and time, and brings great difficulties to daily inspection and maintenance, but also seriously affects the safe and stable operation of the slag conveying system, thereby interfering with the entire coal-fired power generation production process, reducing power generation efficiency, and increasing production costs.

[0004] To sum up, the existing air-cooled dry slag conveyor cleaning chain has many problems when facing changes in coal quality, and the traditional improvement methods cannot effectively solve them. There is an urgent need for a new technical solution to improve the operating reliability of the cleaning chain and ensure the stable and efficient operation of the slag conveying system. This is also the important background and significance of the research and development of the auxiliary device for improving the operating reliability of the air-cooled dry slag conveyor cleaning chain. Summary of the invention

[0005] The object of the present invention is to provide an auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor. By arranging a foundation pit outside the ground at the lower part of the transition section of the cleaning chain box body and installing a set of ash slag conveying device, when the ash slag accumulation in the cleaning chain box body exceeds its processing capacity, the system is put into operation. The ash slag accumulated in the transition section enters the device through the inlet bin and is pushed forward by the swirling wind blown by the first fan until it is conveyed to the slag bin. When the conveying distance needs to be extended, an extension pipe with a second fan can be connected to assist in the conveying, effectively avoiding the occurrence of cleaning chain failures caused by ash accumulation in the transition section box body of the cleaning chain. Greatly reducing the daily maintenance workload and ensuring the safe and stable operation of the slag conveying system at the same time.

[0006] To achieve the above object, the present invention provides the following technical solutions: An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor, comprising an inlet bin, and a crushing bin is fixedly connected to the bottom of the inlet bin. The inlet bin is mainly used to receive the fine ash slag falling from the cleaning chain of the air-cooled dry slag conveyor, preparing for subsequent processing. A conveying pipe is fixedly connected to the bottom of the crushing bin, and the internal spaces of the inlet bin, the crushing bin and the conveying pipe are interconnected. Such a connected structure enables the fine ash slag to enter the crushing bin from the inlet bin in sequence, and then enter the conveying pipe, realizing a continuous conveying process.

[0007] A pair of driving motors are fixedly installed in parallel on the inner side of the crushing bin, and crushing shafts are installed at the ends of the driving shafts of the pair of driving motors, and the crushing shafts rotate towards the inner side relatively. These two driving motors work simultaneously to drive the crushing shafts to rotate towards each other. When the fine ash slag enters the crushing bin, it will be crushed into smaller particles between the two relatively rotating crushing shafts, facilitating subsequent conveying. The crushing shaft is a net-shaped hollow structure, which has many advantages. On the one hand, it can reduce the weight of the crushing shaft itself, thereby reducing the load that the driving motor needs to overcome when driving its rotation, improving the energy utilization efficiency and reducing energy consumption; on the other hand, its unique structure helps to prevent ash slag caking. During the rotation process, when caked ash slag enters between the crushing shafts, the net-shaped hollow structure of the crushing shaft can effectively crush the caked ash slag, ensuring that the ash slag enters the subsequent conveying link in a fine particle state and avoiding problems such as conveying blockage caused by caking.

[0008] The tail end of the conveying pipe is penetrated by a fan pipe, and the tail end of the fan pipe is hermetically connected to the air outlet of the first fan through a conical rubber sleeve. When the first fan works, through the fan pipe and the conveying pipe, wind is provided to the conveying pipe, and the crushed fine ash slag is conveyed along the conveying pipe by using the wind, realizing the function of auxiliary conveying. The conical rubber sleeve can not only ensure sealing and prevent air leakage, but also adapt to the possible position deviation between the fan pipe and the first fan to a certain extent, ensuring the stability of the connection.

[0009] An outer disc is fixedly sleeved on the outer side of the front end of the first fan, and the first fan is fixed to the outer disc near the outer circle. An extension shaft is arranged with the center of the outer disc facing the rear end of the first fan, and the extension shaft is perpendicular to the outer disc. The outer disc is mainly arranged to cooperate with the function of realizing the circular rotation of the fan outlet, and the extension shaft provides a support shaft for the rotation of the outer disc to ensure that the outer disc can rotate stably. The outer disc and the rear end of its extension shaft are rotatably connected to the first base and the second base respectively. With the support of these two bases, the outer disc and the first fan can stably rotate in a circle around the extension shaft, thereby driving the fan outlet to perform a circular rotation.

[0010] The outer disk is provided with a single-sided gear, and the first base is additionally provided with a motor platform, on which a rotating motor is fixedly installed, and a gear is installed on the rotating shaft of the rotating motor, and the gear is meshed with the single-sided gear provided on the outer disk. When the rotating motor is working, the gear on its rotating shaft drives the single-sided gear of the outer disk to rotate, and accurately controls the rotation angle and speed of the outer disk and the first fan fixed thereon, so that the fan outlet can rotate in a circle according to the set trajectory. The fan outlet moves in a circular motion, and the blown wind itself has a tendency to rotate. When the wind enters the conveying pipeline, it is constrained by the pipeline wall, and the movement direction and speed distribution of the wind change, forming a spiral swirl wind that moves along the axial direction of the pipeline while rotating around the central axis of the pipeline. Such a swirl wind can more effectively push the fine ash slag forward, so that the wind power covers a wider range, acts more evenly on the fine ash slag in the conveying pipeline, avoids the situation of local poor conveying, greatly improves the efficiency and stability of auxiliary conveying, and meets the slag conveying requirements under different working conditions.

[0011] The height of the first base and the second base is set with the outer disk, so that the extension axis of the outer disk is parallel to the ground, and it is ensured that the first fan does not separate from the conical rubber sleeve when rotating with the outer disk. Reasonable setting of the base height ensures that the extension axis of the outer disk is parallel to the ground, which can ensure the stability of the rotation of the outer disk and the first fan, and at the same time ensure that the first fan is stably connected to the fan pipe during the rotation process, and will not separate from the conical rubber sleeve due to rotation, affecting the sealing and wind transmission effect.

[0012] The outer disc extension shaft is coaxial with the fan tube. Such a coaxial design can ensure that the air outlet of the first fan is always well connected with the fan tube during rotation, avoiding the problem of wind loss or poor transmission caused by misalignment, and further improving the efficiency and stability of wind transmission.

[0013] Transverse guide rails are fixedly provided on both sides of the conveying pipeline, and steering wheels are installed at both ends of the bottom side of the transverse guide rails. The arrangement of the transverse guide rails and the steering wheels allows the conveying pipeline to move laterally and turn within a certain range. This device can not only be used on flat ground, but also can be used in a foundation pit outside the ground at the lower part of the transition section of the cleaning chain box, and guide rails are arranged inside the foundation pit to slide and guide with the transverse guide rails. Through this design, when the device needs to be installed near the transition section of the cleaning chain box, the conveying pipeline can use the cooperation of the foundation pit guide rails and its own transverse guide rails to more accurately locate and adjust the position, thereby improving the adaptability of the device in complex installation environments and facilitating flexible layout according to actual slag conveying needs.

[0014] The device also includes an extension pipe, which includes a pipe body. A rubber expansion sleeve is fixedly installed at the rear end of the pipe body, and the pipe body and the rubber expansion sleeve are connected to each other. The extension pipe is mainly used to connect to the conveying pipe when the conveying distance needs to be increased. The rubber expansion sleeve can not only ensure the sealing of the connection, but also adapt to the possible position deviation and expansion requirements between pipes. An opening is provided at the top of the pipe body near the rear end, and a second fan is fixedly and sealed at the opening. The second fan is obliquely connected, and the main direction is toward the front end of the pipe body. The second fan is installed obliquely, and the wind it blows can form a certain airflow direction and flow rate in the pipe body, assisting the forward transportation of fine ash and slag, and further improving the conveying capacity.

[0015] The tail end of the rubber expansion sleeve can be tightly connected to the outlet end of the conveying pipe; and the tail end of the rubber expansion sleeve can be tightly connected to the outlet end of other extension pipes. This design of tight connection makes the installation and removal of the extension pipe very convenient, and the user can flexibly increase or decrease the number of extension pipes according to actual needs to meet different conveying distance requirements.

[0016] Auxiliary transverse guide rails are fixedly arranged on both sides of the pipeline body, and steering wheels are installed at both ends of the bottom side of the auxiliary transverse guide rails. Similar to the conveying pipeline, the setting of the auxiliary transverse guide rails and the steering wheels facilitates the adjustment of the position and direction of the extended pipeline during installation and use, so that it can better adapt to the conveying pipeline and the entire slag conveying system.

[0017] During operation, the fine ash residues falling from the cleaning chain first enter the inlet bin and then fall into the crushing bin by gravity. The meshed hollow structure crushing shaft rotating relatively in the bin crushes the ash residues into small particles under the drive of the drive motor, and then the fine ash residues enter the conveying pipeline. At this time, the first blower blows air into the pipeline through the blower pipe. Its outer disc drives the blower to make a circular motion under the drive of the rotating motor, so that the blown air forms a spiral swirling air flow in the pipeline to push the fine ash residues forward. Moreover, the conveying pipeline can be adjusted in position on the flat ground or with the help of the foundation pit guide rail through the transverse guide rail and the steering wheel. When the conveying distance needs to be increased, the extension pipeline is tightly connected by the rubber expansion sleeve. The second blower obliquely installed on the extension pipeline assists in conveying, and its auxiliary transverse guide rail and steering wheel also facilitate the adjustment of its own position and direction.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The use of the meshed hollow structure crushing shaft effectively reduces the load of the drive motor, improves the energy utilization efficiency, and at the same time can prevent the ash residues from caking, ensuring that the fine ash residues enter the conveying link in good condition; the air outlet of the blower rotates in a circular shape, and the generated spiral swirling air flow more efficiently pushes the fine ash residues forward, avoiding local blockage in conveying and greatly improving the conveying efficiency.

[0019] The conveying pipeline of this device is equipped with a transverse guide rail and a steering wheel, which can move and turn flexibly on the flat ground and can also cooperate with the foundation pit guide rail at the lower part of the transition section of the cleaning chain box to accurately position and adapt to complex installation environments; the extension pipeline is flexibly connected by the rubber expansion sleeve, which is convenient for increasing or decreasing the quantity to meet the requirements of different conveying distances. Compared with the prior art, it can better cope with various working condition changes.

[0020] The unique design of the outer disc and the first blower makes the blower operate more smoothly during operation, reducing the component wear and the probability of failure caused by the vibration of the blower; at the same time, the sealing connection method of the conical rubber sleeve not only ensures the stability of pneumatic conveying, but also extends the service life of the equipment, reducing the equipment maintenance frequency and replacement cost.

[0021] By optimizing the conveying process, the leakage and dust raising phenomena of the fine ash residues are reduced, and the pollution to the surrounding environment is lowered; moreover, the overall structure of the equipment is compact, occupying a small area, and high-efficiency slag conveying can be realized in a limited space, which is beneficial to the reasonable planning of the site and the cleanliness of the environment.

[0022] This auxiliary device can be used in cooperation with various air-cooled dry slag conveyors of different models and specifications, without the need for large-scale transformation of the original slag conveying system, and can be quickly integrated into the existing production process, reducing the cost and time of equipment replacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of an auxiliary device for improving the operation reliability of the cleaning chain of an air-cooled dry slag conveyor according to the present invention; Figure 2 It is a schematic diagram of a crushing shaft of an auxiliary device for improving the operating reliability of a cleaning chain of an air-cooled dry slag conveyor according to the present invention; Figure 3 This is a schematic diagram of the extended pipeline structure of an auxiliary device for improving the operating reliability of a cleaning chain of an air-cooled dry slag conveyor according to the present invention; In the figure: 1. inlet bin, 2. crushing bin, 3. conveying pipeline, 4. extension pipeline, 5. outer plate, 21. driving motor, 22. crushing shaft, 31. fan pipe, 32. conical rubber sleeve, 33. first fan, 34. transverse guide rail, 41. pipeline body, 42. rubber telescopic sleeve, 43. second fan, 44. auxiliary transverse guide rail, 51. first base, 52. second base, 53. rotating motor. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be fully described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0025] like Figures 1-3 As shown, an auxiliary device for improving the operating reliability of a cleaning chain of an air-cooled dry slag conveyor includes an inlet bin 1, characterized in that a crushing bin 2 is fixedly connected to the bottom of the inlet bin 1, a conveying pipeline 3 is fixedly connected to the bottom of the crushing bin 2, and the internal spaces of the inlet bin 1, the crushing bin 2 and the conveying pipeline 3 are interconnected; A pair of drive motors 21 are fixedly installed in parallel inside the crushing chamber 2, and a crushing shaft 22 is installed on the drive shafts of the pair of drive motors 21, and the crushing shafts 22 rotate relatively toward the inside; A fan pipe 31 runs through the tail end of the delivery pipeline 3 , and the tail end of the fan pipe 31 is sealed and connected to the air outlet of the first fan 33 through a conical rubber sleeve 32 .

[0026] An outer disk 5 is fixedly sleeved on the outer side of the front end of the first fan 33. The first fan 33 is fixed to the outer disk 5 near the outer circle. An extension shaft is provided with the center of the outer disk 5 toward the rear end of the first fan 33, and the extension shaft is perpendicular to the outer disk 5. The outer disk 5 and the rear end of its extension shaft are rotatably connected to a first base 51 and a second base 52 respectively.

[0027] The outer disk 5 is provided with a single-sided gear, the first base 51 is additionally provided with a motor platform, a rotating motor 53 is fixedly installed on the motor platform, a gear is installed on the rotating shaft of the rotating motor 53, and the gear is meshed with the single-sided gear provided on the outer disk 5.

[0028] The heights of the first base 51 and the second base 52 are set along with the outer disk 5 , so that the extension axis of the outer disk 5 is parallel to the ground and ensures that the first fan 33 does not separate from the conical rubber sleeve 32 when rotating along with the outer disk 5 .

[0029] The extension shaft of the outer disc 5 is coaxial with the fan pipe 31.

[0030] Transverse guide rails 34 are fixedly arranged on both sides of the conveying pipeline 3, and steering wheels are installed at both ends of the bottom side of the transverse guide rails 34.

[0031] The device further includes an extension pipeline 4. The extension pipeline 4 includes a pipeline main body 41. A rubber expansion sleeve 42 is fixedly installed at the tail end of the pipeline main body 41, and the inside of the pipeline main body 41 communicates with the inside of the rubber expansion sleeve 42. An opening is provided at the top of the pipeline main body 41 near the tail end, and a second fan 43 is fixedly and sealingly clamped at the opening. The second fan 43 is obliquely clamped, and its direction faces the front end of the pipeline main body 41.

[0032] The tail end of the rubber expansion sleeve 42 can be tightly clamped and connected to the outlet end of the conveying pipeline 3; and the tail end of the rubber expansion sleeve 42 can be tightly clamped and connected to the outlet end of other extension pipelines.

[0033] Auxiliary transverse guide rails 44 are fixedly arranged on both sides of the pipeline main body 41, and steering wheels are installed at both ends of the bottom side of the auxiliary transverse guide rails 44.

[0034] The crushing shaft 22 is a net-shaped hollow structure.

[0035] When implementing the auxiliary device for improving the operation reliability of the cleaning chain of the air-cooled dry slag conveyor, first install the inlet bin 1 in a suitable position, firmly connect its bottom to the crushing bin 2, and ensure that the internal spaces of the two and the conveying pipeline 3 communicate with each other. Install a pair of drive motors 21 in parallel on the inner side of the crushing bin 2, and install crushing shafts 22 that rotate relative to the inner side at the ends of the motor drive shafts. Use their mesh-shaped hollow structures to efficiently crush the fine ash slag falling from the inlet bin. Then, connect the conveying pipeline 3 to the bottom of the crushing bin 2, penetrate the fan pipe 31 at the end of the conveying pipeline 3, and then seal and connect the air outlet of the first fan 33 through a conical rubber sleeve 32 to convey the crushed ash slag by wind power. At the same time, install horizontal guide rails 34 on both sides of the conveying pipeline 3, and install turning wheels at both ends of the bottom side of the guide rails. When the device is used for the lower part of the transition section of the cleaning chain box body, a foundation pit can be set outside the ground, so that the inner guide rail of the foundation pit is in sliding guide fit with the horizontal guide rail 34 to facilitate the precise positioning and position adjustment of the conveying pipeline. For the first fan 33, an outer disk 5 is fixedly sleeved on the outer side of its front end. The center of the outer disk 5 is provided with an extension shaft facing the tail end direction of the first fan 33. The extension shaft is perpendicular to the outer disk 5. The tail ends of the outer disk 5 and its extension shaft are respectively rotationally connected to the first base 51 and the second base 52. An electric motor platform is added to the first base 51 and a rotating motor 53 is installed, so that the gear on the rotating shaft of the rotating motor 53 meshes with the single-sided gear of the outer disk 5 to realize the circular rotation of the air outlet of the first fan 33. If it is necessary to increase the conveying distance, the extension pipeline 4 with a rubber expansion sleeve 42 is connected to the outlet end of the conveying pipeline 3 or the outlet end of other extension pipelines by a clamping method. The second fan 43 is obliquely clamped at the top of the pipeline main body 41 near the tail end position, and auxiliary horizontal guide rails 44 are installed on both sides of the pipeline main body 41, and turning wheels are installed at both ends of the bottom side of the guide rails to facilitate the position and direction adjustment of the extension pipeline during installation and use.

Claims

1. An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor, including an inlet bin (1), characterized in that, The bottom of the inlet bin (1) is fixedly connected to a crushing bin (2), the bottom of the crushing bin (2) is fixedly connected to a conveying pipeline (3), and the internal spaces of the inlet bin (1), the crushing bin (2), and the conveying pipeline (3) are interconnected; A pair of driving motors (21) are fixedly installed in parallel on the inner side of the crushing bin (2). Crushing shafts (22) are installed on the drive shafts of the pair of driving motors (21), and the crushing shafts (22) rotate towards the inner side relatively; The tail end of the conveying pipeline (3) is penetrated by a blower pipe (31), and the tail end of the blower pipe (31) is hermetically connected to the air outlet of a first blower (33) through a conical rubber sleeve (32).

2. The auxiliary device for improving the operation reliability of the cleaning chain of the air-cooled dry slag conveyor according to claim 1, wherein, An outer disc (5) is fixedly sleeved on the outer side of the front end of the first blower (33). The first blower (33) is fixed at a position close to the outer circle of the outer disc (5). An extension shaft is arranged at the center of the outer disc (5) towards the tail end direction of the first blower (33), and the extension shaft is perpendicular to the outer disc (5); The outer disc (5) and the tail end of its extension shaft are respectively rotatably connected to a first base (51) and a second base (52).

3. An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 2, characterized in that, The outer disc (5) is provided with a single-sided gear. The first base (51) is provided with a motor platform, and a rotating motor (53) is fixedly installed on the motor platform. A gear is installed on the rotating shaft of the rotating motor (53), and the gear meshes with the single-sided gear arranged on the outer disc (5).

4. An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 2, characterized in that, The heights of the first base (51) and the second base (52) are set according to the outer disc (5), so that the extension shaft of the outer disc (5) is parallel to the ground, and it is ensured that the first blower (33) does not disengage from the conical rubber sleeve (32) when the outer disc (5) rotates.

5. An auxiliary device for improving the operation reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 4, characterized in that, The extension shaft of the outer disc (5) is coaxial with the blower pipe (31).

6. An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 1, characterized in that Transverse guide rails (34) are fixedly arranged on both sides of the conveying pipeline (3), and steering wheels are installed at both ends of the bottom side of the transverse guide rails (34).

7. An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 1, characterized in that, The device further includes an extension pipeline (4). The extension pipeline (4) includes a pipeline main body (41). A rubber expansion sleeve (42) is fixedly installed at the tail end of the pipeline main body (41), and the inside of the pipeline main body (41) and the rubber expansion sleeve (42) are interconnected; An opening is provided at the top of the pipeline main body (41) near the tail end, and a second blower (43) is fixedly and hermetically clamped at the opening. The second blower (43) is obliquely clamped, and its direction is towards the front end of the pipeline main body (41).

8. An auxiliary device for improving the operation reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 7, characterized in that, The tail end of the rubber expansion sleeve (42) can be tightly clamped and connected to the outlet end of the conveying pipeline (3); and the tail end of the rubber expansion sleeve (42) can be tightly clamped and connected to the outlet ends of other extension pipelines.

9. An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 7, characterized in that, Auxiliary transverse guide rails (44) are fixedly arranged on both sides of the pipeline main body (41), and steering wheels are installed at both ends of the bottom side of the auxiliary transverse guide rails (44).

10. An auxiliary device for improving the running reliability of the cleaning chain of an air-cooled dry slag conveyor according to claim 1, characterized in that, The crushing shaft (22) is a net-shaped hollow structure.

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