Aluminum-magnesium alloy stern tube sleeve welding process and welding structure
By employing a stepped welding and temperature-controlled aluminum-magnesium alloy stern shaft sleeve assembly process, the problem of welding deformation was solved, and high-precision stern shaft sleeve installation was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AFAI SOUTHERN SHIPYARDPANYU GUANGZHOU LTD
- Filing Date
- 2022-11-03
- Publication Date
- 2026-07-24
AI Technical Summary
During the welding process of aluminum-magnesium alloy hull stern shaft sleeves, problems such as bending deformation of the stern shaft sleeve straightness and bending deformation of the stern shaft sleeve from the baseline are prone to occur.
The stern shaft sleeve is pre-positioned with the outer plate, rib frame, transverse reinforcement structure, and longitudinal reinforcement structure using tack welding. Welding is carried out in stages to control welding deformation. Local welding shrinkage and staged welding sequence are adopted to control the welding temperature between 220-300℃. The next layer is welded after the interlayer temperature drops below 60℃. Measurement is taken during welding to control deformation.
The welding deformation was effectively controlled within the standard range, and the concentricity deviation of the stern shaft sleeve was less than 0.20 mm, meeting the installation accuracy requirements and passing the inspection by the shipowner and ship inspection authorities.
Smart Images
Figure CN115673473B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum-magnesium alloy welding technology, specifically to an aluminum-magnesium alloy stern shaft sleeve assembly and welding structure. Background Technology
[0002] Aluminum-magnesium alloys are structural materials for modern high-speed ships. They have high welding strength, low density (2.7%), and a coefficient of expansion that is about three times greater than that of steel-structured ships. Therefore, they are prone to welding deformation during the welding process.
[0003] Due to the concentrated welding heat and large coefficient of linear expansion, defects such as bending deformation of the stern shaft sleeve and bending deformation of the stern shaft sleeve from the baseline are very likely to occur during the welding process of aluminum-magnesium alloy hulls. Summary of the Invention
[0004] The purpose of this invention is to provide a welding process and structure for aluminum-magnesium alloy stern shaft sleeves, in order to solve the problems of bending deformation of the straightness of the stern shaft sleeve and bending deformation of the stern shaft sleeve from the baseline that are easily generated during the welding process of existing aluminum-magnesium alloy hull stern shaft sleeves.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A welding process for aluminum-magnesium alloy stern shaft sleeves, used to weld and fix the stern shaft sleeves to the outer plate, rib frame, transverse reinforcement structure, and longitudinal reinforcement structure, includes the following steps:
[0007] S1: The stern shaft sleeve is pre-positioned with the outer plate, the rib frame and the transverse reinforcing structure and the longitudinal reinforcing structure by means of tack welding;
[0008] S2: Weld the side of the stern shaft sleeve that is not tack welded to the outer plate, then remove the tack weld on the other side of the stern shaft sleeve and the outer plate, and then weld the other side.
[0009] S3: Weld the side of the stern shaft sleeve that is not tack welded to the rib frame and the transverse reinforcing structure, then remove the tack weld on the other side of the stern shaft sleeve that is not tack welded to the rib frame and the transverse reinforcing structure, and then weld the other side.
[0010] S4: Weld the side of the stern shaft sleeve that is not tack welded to the longitudinal reinforcement structure, then remove the tack weld on the other side of the stern shaft sleeve and the longitudinal reinforcement structure, and then weld the other side.
[0011] Furthermore, in step S1, before pre-welding, the stern shaft sleeve is inclined downward at one end of the stern to pre-release the amount of reverse deformation.
[0012] Furthermore, in step S2, when welding the side of the stern tube and the outer plate that is not tack welded, the weld seam is divided into four symmetrical segments: the upper left weld seam is welded counterclockwise, the lower left weld seam is welded clockwise, the upper right weld seam is welded clockwise, and finally the lower right weld seam is welded counterclockwise.
[0013] Furthermore, in step S2, when welding the stern shaft sleeve to the outer plate on the other side after removing the tack weld, the weld seam is divided into two symmetrical sections, with the upper weld seam welded counterclockwise first, and the lower weld seam welded clockwise.
[0014] Furthermore, in step S3, when welding the stern shaft sleeve to the rib frame and the transverse reinforcing structure, the weld seam is divided into four symmetrical segments: the lower left weld seam is welded clockwise, the upper right weld seam is welded counterclockwise, the lower right weld seam is welded counterclockwise again, and finally the upper left weld seam is welded clockwise.
[0015] Furthermore, when there are multiple rib frames and transverse reinforcing structures, multiple rib frames and transverse reinforcing structures are welded sequentially from bow to stern.
[0016] Furthermore, in step S4, when welding the stern shaft sleeve and the longitudinal reinforcement structure, the longitudinal reinforcement structure located below the stern shaft sleeve is welded first from stern to bow, and then the longitudinal reinforcement structure located above the stern shaft sleeve is welded from stern to bow, with the welding directions of adjacent weld seams being opposite.
[0017] Furthermore, when using multi-layer welds, the interpass temperature during the welding process is controlled between 220-300℃.
[0018] Furthermore, after welding one layer of weld, the next layer of weld should be welded only after the interpass temperature drops to 60°C or below. The start and end points of each layer of weld should be staggered by at least 50mm.
[0019] A welding structure for an aluminum-magnesium alloy stern shaft sleeve includes a stern shaft sleeve, an outer plate, a rib frame, a transverse reinforcing structure, and a longitudinal reinforcing structure. The stern shaft sleeve is welded and fixed to the outer plate, the rib frame, the transverse reinforcing structure, and the longitudinal reinforcing structure using the aluminum-magnesium alloy stern shaft sleeve welding process described above.
[0020] The beneficial effects of this invention are:
[0021] The aluminum-magnesium alloy stern shaft sleeve welding process of the present invention adopts local welding shrinkage and a stepped welding sequence to effectively control welding deformation within the standard range. The concentricity deviation of the stern shaft sleeve is less than 0.20mm, which fully meets the installation accuracy requirements of the stern shaft and passes the inspection of the shipowner and ship inspection agency in one go. Attached Figure Description
[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0023] Figure 1 This is a top view showing the assembly relationship between the stern shaft sleeve, outer plate, rib frame, transverse reinforcing structure, and longitudinal reinforcing structure of the present invention.
[0024] Figure 2 for Figure 1 Sectional view along line AA in the middle;
[0025] Figure 3 This is an assembly diagram showing the amount of deformation reserved for the stern shaft sleeve of the present invention.
[0026] Figure 4 This is a schematic diagram showing the welding sequence and direction of the weld seam between the stern shaft sleeve and the outer plate on the side without tack welds, according to the present invention.
[0027] Figure 5 This is a schematic diagram showing the welding sequence and direction of the weld seam between the stern shaft sleeve and the outer plate of the present invention, where there is a tack weld.
[0028] Figure 6 This is a schematic diagram showing the welding sequence and direction of the weld seams between the stern shaft sleeve, the rib frame, and the transverse reinforcing structure of the present invention.
[0029] Figure 7 This is a schematic diagram showing the welding sequence and direction of the weld seam between the stern shaft sleeve and the longitudinal reinforcement structure of the present invention;
[0030] in:
[0031] 10-Stern shaft sleeve; 20-Outer plate; 30-Rib frame and transverse reinforcement structure; 40-Longitudinal reinforcement structure. Detailed Implementation
[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.
[0033] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0035] To address the problems of bending deformation of the stern shaft sleeve and bending deformation of the stern shaft sleeve from the baseline that easily occur during the welding process of aluminum-magnesium alloy stern shaft sleeves, this invention provides an aluminum-magnesium alloy stern shaft sleeve assembly and welding process and assembly structure.
[0036] like Figures 1 to 7 As shown in this embodiment, an aluminum-magnesium alloy stern tube welding process is provided to weld and fix the stern tube 10 to the outer plate 20, the rib frame, the transverse reinforcing structure 30, and the longitudinal reinforcing structure 40, respectively. This ensures that the welding deformation is effectively controlled within the standard range, fully meeting the installation accuracy requirements of the stern tube 10. However, it is not limited to this; it can also be used to weld other workpieces with large welding deformation to reduce the deformation of the welded parts and thus improve the pass rate of the welded parts.
[0037] like Figure 1 and Figure 2 As shown, the stern shaft sleeve 10 and the outer plate 20 are arranged at an angle, thereby forming an elliptical weld seam on both sides of the outer plate 20. Multiple rib frames and transverse reinforcing structures 30 can be provided and distributed at intervals along the axial direction of the stern shaft sleeve 10, forming a circular weld seam on both sides of the rib frames and transverse reinforcing structures 30. The longitudinal reinforcing structure 40 is provided on the upper and lower sides of the stern shaft sleeve 10, forming a horizontally extending weld seam with the stern shaft sleeve 10. The number of weld seams is changed accordingly based on the number of rib frames and transverse reinforcing structures 30.
[0038] like Figure 3 As shown, during the installation of the stern shaft sleeve 10, the amount of pre-deformation is determined according to the structural form and the amount of welding. In this embodiment, the welding direction is from bottom to top, and the pre-deformation is from bottom to top. By adjusting the subsequent welding direction, the number of welding layers, and measuring while welding, the stern shaft sleeve 10 is made to move from the anti-deformation installation position to the theoretical installation position.
[0039] like Figures 4 to 7 As shown, the welding process for the stern shaft sleeve specifically includes:
[0040] S1: The stern shaft sleeve 10 is pre-positioned with the outer plate 20, the rib frame and the transverse reinforcing structure 30 and the longitudinal reinforcing structure 40 by means of tack welding;
[0041] S2: Weld the side of the stern shaft sleeve 10 and the outer plate 20 that is not tack welded, then remove the tack weld on the other side of the stern shaft sleeve 10 and the outer plate 20, and then weld the other side.
[0042] S3: Weld the side of the stern shaft sleeve 10 to the rib frame and the transverse reinforcing structure 30 that has no tack weld, then remove the tack weld on the other side of the stern shaft sleeve 10 to the rib frame and the transverse reinforcing structure 30, and then weld the other side.
[0043] S4: Weld the side of the stern shaft sleeve 10 and the longitudinal reinforcing structure 40 that is not tack welded, then remove the tack weld on the other side of the stern shaft sleeve 10 and the longitudinal reinforcing structure 40, and then weld the other side.
[0044] For step S1, after the stern shaft sleeve 10 is installed, it is pre-positioned with the outer plate 20, the rib frame and the transverse reinforcing structure 30, and the longitudinal reinforcing structure 40 using tack welding to ensure the positional accuracy of the stern shaft sleeve 10 during subsequent welding. Specifically, the tack weld between the stern shaft sleeve 10 and the outer plate 20 is located on the outer surface of the outer plate 20, i.e., the side of the outer plate 20 facing the stern. The tack weld between the stern shaft sleeve 10 and the rib frame and the transverse reinforcing structure 30 is located on the side of the rib frame and the transverse reinforcing structure 30 facing the stern. The tack weld between the stern shaft sleeve 10 and the longitudinal reinforcing structure 40 is not specifically required; all welds can be on the same side. Optionally, spot welding is used for tack welding in this embodiment.
[0045] For step S2, first weld the side of the stern shaft sleeve 10 and the outer plate 20 that is not tack welded, dividing the elliptical weld seam into four symmetrical segments (top, bottom, left, and right), according to... Figure 4 The welding sequence and direction shown in ①-②-③-④ are applied as follows: First, weld the upper left weld counterclockwise, then weld the lower left weld clockwise, then weld the upper right weld clockwise, and finally weld the lower right weld counterclockwise. This welding method, with two consecutive welded sections in opposite directions, allows each section's starting point more time to dissipate heat, which is beneficial for the earlier welded portion of adjacent sections, thus reducing the interpass temperature of the weld.
[0046] After welding the side of the stern tube sleeve 10 to the outer plate 20 without tack welds, weld the side with tack welds. First, clean the tack welds and weld slag from the stern face of the outer plate 20, then use mechanical methods for root cleaning, such as an angle grinder, and perform a colorimetric inspection to ensure there are no defects. Then proceed according to... Figure 5 The welding sequence and direction shown in ⑤-⑥ are applied. Specifically, the weld seam is divided into two symmetrical sections, with the upper section welded counterclockwise first, and the lower section welded clockwise.
[0047] For step S3, first weld the side of the stern shaft sleeve 10 to the rib frame and the transverse reinforcing structure 30 that has no tack weld, dividing the circular weld seam into four symmetrical segments (top, bottom, left, and right), according to... Figure 6 The welding sequence and direction shown are ⑦-⑧-⑨-⑩. Specifically, weld the lower left weld seam clockwise first, then the upper right weld seam counterclockwise, then the lower right weld seam counterclockwise again, and finally the upper left weld seam clockwise. This welding method, with the two consecutive welded sections spaced apart, avoids the temperature rise of the first welded section affecting the subsequent welded sections. Furthermore, the symmetrical arrangement of the two consecutive welded sections helps to offset welding stress. In addition, the time interval between welding adjacent sections facilitates heat dissipation from the first welded section, thereby reducing the interpass temperature of the weld seam.
[0048] After welding the stern shaft sleeve 10 to the rib frame and transverse reinforcing structure 30 on the side without tack welds, weld the side with tack welds. First, clean the tack welds and weld slag from the stern face of the rib frame and transverse reinforcing structure 30, perform root cleaning and coloring checks to ensure there are no defects, and then weld the other side according to the instructions. Figure 6 Welding should be performed in the sequence and direction shown in ⑦-⑧-⑨-⑩.
[0049] In addition, when there are multiple rib frames and transverse reinforcing structures 30, they are welded sequentially from bow to stern, and each rib frame and transverse reinforcing structure 30 is welded according to the method shown in step S3.
[0050] For step S4, when welding the stern shaft sleeve 10 and the longitudinal reinforcing structure 40, the side without tack welds is welded first, according to... Figure 7 The welding sequence and direction shown in 11-12-13-14 are as follows: First, the longitudinal reinforcing structure 40 located below the stern shaft sleeve 10 is welded from stern to bow, and then the longitudinal reinforcing structure 40 located above the stern shaft sleeve 10 is welded from stern to bow. The welding directions of adjacent weld seams are opposite.
[0051] After welding the side of the stern shaft sleeve 10 to the longitudinal reinforcement structure 40 without tack welds, weld the side with tack welds. First, clean the tack welds and slag from the longitudinal reinforcement structure 40, perform root cleaning and coloring checks to ensure there are no defects, and then weld the other side according to the instructions. Figure 7 Welding sequence and direction as shown in 11-12-13-14.
[0052] In this embodiment, when the stern shaft sleeve 10 is welded to the outer plate 20, the rib frame, the transverse reinforcing structure 30, and the longitudinal reinforcing structure 40, if the plate thickness exceeds a certain thickness, multi-layer welds are required. At this time, the current of the welding gun needs to be controlled during the welding process so that the interpass temperature of the weld is controlled between 220-300℃. In this way, while ensuring the welding effect, the amount of welding deformation can be reduced to the greatest extent.
[0053] To further reduce welding deformation, after welding one layer of weld, the interpass temperature should be lowered to 60°C or below before welding the next layer of weld. The start and end points of each layer of weld should be staggered by at least 50mm.
[0054] Furthermore, measurements must be taken simultaneously during welding to control deformation to the greatest extent possible. Specifically, after the stern shaft sleeve 10 is installed, a set of data is measured, mainly the inner diameter and axis dimensions of the stern shaft sleeve 10. The welding sequence is adjusted based on the data after installation. During welding, the dimensions of the stern shaft sleeve 10 and axis must be measured after each weld. Welding shrinkage and deformation vary, and the weld between the stern shaft sleeve 10 and the outer plate 20 requires 2-3 welding processes to complete. Figure 4 The welding process is illustrated in the diagram, and the others are similar. For example... Figure 4 In the process of welding the first weld, the stern shaft sleeve 10 needs to be measured relative to the axis before welding the second weld. After measuring the data, the third and fourth welds are completed in the same manner. If the stern shaft sleeve 10 shifts outwards after measurement, the welding sequence needs to be adjusted. During the second welding process, welds ② and ④ can be completed first; conversely, welds ① and ③ should be completed first. If there is no deviation, proceed as planned. Figure 4 This indicates that welding is to be performed.
[0055] In summary, the aluminum-magnesium alloy stern shaft sleeve welding process of this application adopts pre-deformation adjustment during assembly and installation, and a staggered welding technique. The welding temperature is strictly controlled between 220-300℃, and cross-shaped fixed measuring points are used at the ends. After welding the previous weld, the interpass temperature is allowed to drop to about 60℃ before welding the next weld. During the welding process, measurements are taken while welding to control deformation. The concentricity deviation of the stern shaft sleeve 10 is less than 0.20mm, which fully meets the installation accuracy requirements of the stern shaft. Moreover, the process technology is highly operable, and it is easy to meet the process parameter data when constructed according to the requirements.
[0056] This embodiment also provides a welding structure for an aluminum-magnesium alloy stern shaft sleeve, including a stern shaft sleeve 10, an outer plate 20, a rib frame, a transverse reinforcing structure 30, and a longitudinal reinforcing structure 40. The stern shaft sleeve 10 is welded and fixed to the outer plate 20, the rib frame, the transverse reinforcing structure 30, and the longitudinal reinforcing structure 40 using the aluminum-magnesium alloy stern shaft sleeve welding process described in any of the above-mentioned technical solutions. Through the above-described welding process, the welding deformation of the stern shaft sleeve 10 can be effectively controlled within the standard range, allowing it to pass the inspection by the shipowner and ship inspection authorities in one go.
[0057] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.
[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0059] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.
[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A welding process for an aluminum-magnesium alloy stern shaft sleeve, used to weld and fix the stern shaft sleeve (10) to the outer plate (20), the rib frame and the transverse reinforcing structure (30), and the longitudinal reinforcing structure (40), characterized in that, Includes the following steps: S1: The stern shaft sleeve (10) is pre-positioned with the outer plate (20), the rib frame and the transverse reinforcing structure (30), and the longitudinal reinforcing structure (40) by means of tack welding; S2: Weld the side of the stern shaft sleeve (10) and the outer plate (20) that is not tack welded, then remove the tack weld on the other side of the stern shaft sleeve (10) and the outer plate (20), and then weld the other side. When welding the side of the stern shaft sleeve (10) and the outer plate (20) that has no tack weld, the weld seam is divided into four symmetrical sections, and the welding sequence is as follows: first weld the upper left weld seam counterclockwise, then weld the lower left weld seam clockwise, then weld the upper right weld seam clockwise, and finally weld the lower right weld seam counterclockwise. During the welding process, measurements are taken simultaneously to determine the inner diameter of the stern shaft sleeve (10) relative to its axis. Based on the measured data, the welding sequence of the four weld seams is adjusted: if the stern shaft sleeve (10) shifts outward, the lower left and lower right weld seams are completed first; if the stern shaft sleeve (10) shifts inward, the upper left and upper right weld seams are completed first; if no deviation occurs, welding is performed according to the preset sequence. S3: Weld the side of the stern shaft sleeve (10) and the rib frame and transverse reinforcing structure (30) that is not tack welded, then remove the tack weld on the other side of the stern shaft sleeve (10) and the rib frame and transverse reinforcing structure (30), and then weld the other side. S4: Weld the side of the stern shaft sleeve (10) and the longitudinal reinforcement structure (40) that is not tack welded, then remove the tack weld on the other side of the stern shaft sleeve (10) and the longitudinal reinforcement structure (40), and then weld the other side.
2. The aluminum-magnesium alloy stern shaft sleeve assembly and welding process according to claim 1, characterized in that: In step S1, the stern bushing (10) is tilted downward at one end of the stern before pre-welding to allow for the amount of reverse deformation.
3. The aluminum-magnesium alloy stern shaft sleeve assembly and welding process according to claim 2, characterized in that: In step S2, when welding the stern shaft sleeve (10) and the outer plate (20) and removing the other side of the tack weld, the weld seam is divided into two symmetrical sections. First, the upper weld seam is welded counterclockwise, and then the lower weld seam is welded clockwise.
4. The aluminum-magnesium alloy stern shaft sleeve assembly and welding process according to claim 1, characterized in that: In step S3, when welding the stern shaft sleeve (10) to the rib frame and the transverse reinforcing structure (30), the weld seam is divided into four symmetrical segments: the lower left weld seam is welded clockwise, the upper right weld seam is welded counterclockwise, the lower right weld seam is welded counterclockwise, and finally the upper left weld seam is welded clockwise.
5. The aluminum-magnesium alloy stern shaft sleeve assembly and welding process according to claim 4, characterized in that: When there are multiple rib frames and transverse reinforcing structures (30), multiple rib frames and transverse reinforcing structures (30) are welded sequentially from bow to stern.
6. The aluminum-magnesium alloy stern shaft sleeve assembly and welding process according to claim 1, characterized in that: In step S4, when welding the stern shaft sleeve (10) and the longitudinal reinforcing structure (40), the longitudinal reinforcing structure (40) located below the stern shaft sleeve (10) is welded first from stern to bow, and then the longitudinal reinforcing structure (40) located above the stern shaft sleeve (10) is welded from stern to bow. The welding directions of the two adjacent weld seams are opposite.
7. The aluminum-magnesium alloy stern shaft sleeve assembly and welding process according to claim 1, characterized in that: When using multi-layer welds, the interpass temperature during the welding process is controlled between 220-300°C.
8. The aluminum-magnesium alloy stern shaft sleeve assembly and welding process according to claim 7, characterized in that: After welding one layer of weld, the next layer of weld should be welded only after the interpass temperature drops to 60°C or below. The start and end points of each layer of weld should be staggered by at least 50mm.
9. A welding structure for an aluminum-magnesium alloy stern shaft sleeve, comprising a stern shaft sleeve (10), an outer plate (20), a rib frame, a transverse reinforcing structure (30), and a longitudinal reinforcing structure (40), characterized in that: The stern tube (10) is welded and fixed to the outer plate (20), the rib frame and the transverse reinforcing structure (30), and the longitudinal reinforcing structure (40) using the aluminum-magnesium alloy stern tube welding process described in any one of claims 1-8.
Citation Information
Patent Citations
Welding method of rudder sleeve
CN112388197A