A method for replacing a main hinge bearing of a stern gate of a docked ship

Abstract

This application discloses a method for replacing the main hinge bearing of a stern door of a ship docked at a wharf, comprising the following steps: S1 Support positioning: A support platform is set up in the area corresponding to the stern door of the ship docking position, and the ship's stern door is opened and smoothly placed on the support platform; S2 Reference locking: A limiting support fixture is installed at the hull end of the main hinge of the stern door; S3 Pre-processing disassembly and inspection: The peripheral auxiliary structures of the main hinge are removed; S4 Non-destructive disassembly: After calibrating the coaxiality of the main hinge hole, the main shaft and the old bearing to be replaced are sequentially pushed out and removed from the hinge eye plate; S5 Bearing reinstallation: The new bearing is smoothly pressed into the designed installation position of the hinge eye plate using a special pressing fixture in conjunction with a hydraulic jacking fixture; S6 Reset and acceptance: The main shaft is inserted into the inner hole of the new bearing, and the bushing, sealing structure, and peripheral auxiliary structures of the main hinge are sequentially reset and installed. This method eliminates the reliance on dry docks and large-tonnage floating cranes, significantly reducing maintenance costs.

Description

Technical Field

[0001] This application relates to the technical field of shipbuilding and repair, and in particular to a method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf. Background Technology

[0002] The stern door is the core loading and unloading equipment of roll-on / roll-off ships, and the main hinge bearing is the core component of its slewing support. It is subjected to heavy loads and marine salt spray corrosion for a long time, and is prone to failure due to lubrication failure and wear and jamming. It needs to be replaced in time to ensure the normal operation of the ship.

[0003] Existing bearing replacement solutions mainly fall into two categories: one is the in-dock disassembly and assembly solution, which requires the vessel to enter the dry dock and the stern door to be disassembled as a whole using large lifting equipment. This solution has inherent drawbacks such as high dock entry costs, limited dock resources, long construction periods, and inability to meet the urgent maintenance needs of the dock. The other is the dock-side floating crane lifting solution, which is currently the only feasible technology at the dock stage. This solution uses a large-tonnage floating crane to lift the stern door hinge end to create working space. However, this solution has fatal flaws: firstly, the safety risks are extremely high. The lifting of a stern door weighing hundreds of tons is greatly affected by wind, waves, and tides. Flexible lifting cannot rigidly lock the posture, which can easily lead to structural collisions and irreversible damage to the equipment; secondly, it is highly dependent on resources and has high costs. The rental cost of large-tonnage floating cranes is expensive, and the availability is uncontrollable; thirdly, the construction precision is poor. Manual coarse adjustments cannot guarantee the coaxiality of the hinge, which can easily lead to the failure of the new bearing due to uneven loading, resulting in a high rework rate. Moreover, the construction window is strictly limited by the weather.

[0004] Therefore, there is currently no mature in-situ, non-lifting bearing replacement solution for docks, which cannot simultaneously solve the problems of safety, accuracy, cost, and efficiency in dock maintenance. There is an urgent need to develop a safe and controllable method for replacing dock stern gate bearings that is free from dependence on large lifting equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf, which can solve the above-mentioned problems existing in related technologies.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] A method for replacing the main hinge bearing of the stern door of a ship docked at a wharf includes the following steps: S1 Support in place: Set up a support platform in the area corresponding to the stern door of the ship's berthing position at the dock, open the ship's stern door and place it smoothly on the support platform, and loosen the traction steel cable of the stern door to a slack state. S2 reference locking: A limiting support fixture is installed at the hull end of the stern door main hinge. The limiting support fixture limits the relative position of the hull end hinge and the stern door end hinge eye plate, and the hull end main hinge remains in a non-disassembly state throughout the entire process. S3 Pre-processing Disassembly and Inspection: Remove the peripheral auxiliary structures of the main hinge to fully expose the main shaft, bearing to be replaced and bushing of the main hinge, and complete the cleaning and condition inspection of the parts to be replaced. S4 Non-destructive Disassembly: The spatial orientation of the stern door hinge eye plate is adjusted by using a traction adjustment tool in conjunction with a hydraulic jacking tool. After calibrating the coaxiality of the main hinge hole, the main shaft and the old bearing to be replaced are pushed out and removed from the hinge eye plate in sequence. S5 bearing reinstallation: Clean the mounting surface of the hinge eye plate, lubricate the new bearing, and then use a special pressing tool and a hydraulic jacking tool to press the new bearing smoothly into the designed installation position of the hinge eye plate, and calibrate the coaxiality of the new bearing with the hull end hinge. S6 Reset Acceptance: Insert the main shaft into the inner hole of the new bearing, and then reset and install the bushing, sealing structure and peripheral structures of the main hinge in sequence. After completing the lubrication and installation accuracy verification, the replacement of the stern door main hinge bearing is completed.

[0008] Optionally, in step S1, the support platform is a modular outfitting platform, and the load-bearing capacity of the modular outfitting platform is not less than 1.2 times the total weight of the stern door.

[0009] Optionally, in step S2, the limiting support fixture includes a hull end fixed seat and a hinge limiting block. The hull end fixed seat is rigidly connected to the hull main hinge base. The hinge limiting block restricts the vertical and axial displacement of the stern door end hinge eye plate to no more than 0.1mm, with the hull end main hinge as the positioning reference for the entire construction process.

[0010] Optionally, in step S3, the dismantling sequence of the peripheral auxiliary structures is as follows: the end caps on the left and right sides of the main hinge, the hinge seat cover, and the bearing seal cover are removed in sequence. During the dismantling process, each component is numbered and protected to prevent the loss or damage of bolts and seals.

[0011] Optionally, in step S4, when adjusting the hinge eye plate posture, a feeler gauge is used to measure the fit clearance between the bushing and the hinge hole in real time, and a bidirectional limit adjustment is performed by using a rigid support seat in the vertical and axial directions in conjunction with a hydraulic jack; when removing the main shaft and the old bearing, a special disassembly tooling is used that is fixed coaxially with the hinge eye plate, and a ring of evenly distributed hydraulic jacks is used to push synchronously to ensure that there is no off-center load during the pushing process.

[0012] Optionally, in steps S5 and S6, before pressing the new bearing, the dimensional accuracy and cleanliness of the bearing inner hole and outer ring must be checked. The lubrication pretreatment uses a special grease that matches the bearing model to fill the entire raceway. Before the spindle is installed, a transition fillet of R10mm needs to be machined at the end of the spindle. During the installation process, the bushing seal ring is installed simultaneously. After the installation is completed, the circumferential position of the shaft end plate is adjusted to ensure that it is coaxially aligned with the end cover bolt hole.

[0013] Optionally, in step S1, the support platform adopts an array-type hydraulic servo support platform. The array-type hydraulic servo support platform integrates a load sensor, a displacement sensor, and a tide level linkage control unit. During construction, it collects real-time data on tide level changes and ship attitude, dynamically adjusts the lifting displacement and load of each support point, and maintains that the relative positional deviation between the stern door and the main hinge at the hull end does not exceed 0.5mm throughout the process.

[0014] Optionally, in steps S4 and S5, when the old bearing is stuck, a medium-frequency induction heating fixture is used to uniformly heat the outer ring of the bearing in a ring. The heating temperature is controlled at 80-120℃. After eliminating the interference fit, non-destructive disassembly is completed. Before pressing the new bearing, a deep cryogenic treatment process is used to cool the new bearing to -40℃~-60℃ and keep it at that temperature for 2-4 hours. This allows the outer ring of the bearing to shrink and eliminate the interference fit before pressing.

[0015] Optionally, in steps S2, S4, and S5, a high-precision laser reference target is set on the main hinge base at the hull end. The coaxiality and parallelism data of the hinge hole are collected in real time by a laser tracker and a vision alignment system. With the help of a six-degree-of-freedom adjustment fixture, the closed-loop automatic adjustment of the hinge eye plate attitude is realized, and the coaxiality control accuracy is not less than 0.01mm.

[0016] Optionally, in step S6, after the installation accuracy verification is completed, in-situ performance verification is carried out, including static testing of the main hinge coaxiality, dynamic testing of the stern door's full-stroke opening and closing, testing of bearing temperature rise and vibration, and testing of the lubrication system pressure holding. Final acceptance is completed after all indicators meet the design requirements.

[0017] The beneficial effects of this application are as follows: Based on the method for replacing the main hinge bearing of the stern door of a vessel docked at a wharf provided in this application, it eliminates the dependence on dry docks and large-tonnage floating cranes. Bearing replacement can be completed on-site at the wharf without the vessel entering the dry dock, significantly reducing maintenance costs and avoiding the risk of delays caused by tight dry dock schedules and uncontrollable floating crane availability. By using a support platform to achieve full-process static stability support for the stern door, combined with the hull-end reference locking fixture, the significant safety risks of large-tonnage lifting operations are completely eliminated. The impact of wind, waves, and severe weather on the construction process is greatly reduced, improving operational safety and ensuring a safer and more secure operation. The controllability of the process is significantly improved. Through precise coaxiality calibration and synchronous jacking process using specialized tooling, non-destructive disassembly and assembly of the main shaft and bearings are achieved, ensuring the installation accuracy of the bearings and avoiding problems such as hinge structure deformation and bearing off-center load failure during disassembly and assembly. This greatly improves the maintenance quality and the service life of the bearings. At the same time, the overall process is highly standardized, easy to operate, and the core tooling can be reused. No large-scale specialized equipment is required. It can be directly applied to the dock maintenance of stern door and gangway hinge bearings of various roll-on / roll-off ships and passenger roll-on / roll-off ships, combining excellent economy, safety and practicality. Attached Figure Description

[0018] The present application will now be described in further detail with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a schematic diagram illustrating the state of a ship docked at a pier for replacing the main hinge bearing, as described in an embodiment of this application. Figure 2 This is a schematic diagram of the stern door main hinge structure as described in an embodiment of this application; Figure 3 This is an axial sectional view of the stern door main hinge described in an embodiment of this application.

[0020] In the picture: 1. Hull; 2. Stern door; 3. Traction cable; 4. Main hinge; 41. End cover; 42. Top cover; 43. Bearing seal cover; 44. Bearing; 45. Main shaft; 46. Bushing; 47. Hinge seat; 5. Support platform. Detailed Implementation

[0021] To make the technical problems solved by this application, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of this application are further described in detail below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In the description of this application, unless otherwise expressly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] The stern door is the core loading and unloading equipment of roll-on / roll-off ships, and the main hinge bearing is the core component of its slewing support. It is subjected to heavy loads and marine salt spray corrosion for a long time, and is prone to failure due to lubrication failure and wear and jamming. It needs to be replaced in time to ensure the normal operation of the ship.

[0025] Existing bearing replacement solutions mainly fall into two categories: one is the in-dock disassembly and assembly solution, which requires the vessel to enter the dry dock and the stern door to be disassembled as a whole using large lifting equipment. This solution has inherent drawbacks such as high dock entry costs, limited dock resources, long construction periods, and inability to meet the urgent maintenance needs of the dock. The other is the dock-side floating crane lifting solution, which is currently the only feasible technology at the dock stage. This solution uses a large-tonnage floating crane to lift the stern door hinge end to create working space. However, this solution has fatal flaws: firstly, the safety risks are extremely high. The lifting of a stern door weighing hundreds of tons is greatly affected by wind, waves, and tides. Flexible lifting cannot rigidly lock the posture, which can easily lead to structural collisions and irreversible damage to the equipment; secondly, it is highly dependent on resources and has high costs. The rental cost of large-tonnage floating cranes is expensive, and the availability is uncontrollable; thirdly, the construction precision is poor. Manual coarse adjustments cannot guarantee the coaxiality of the hinge, which can easily lead to the failure of the new bearing due to uneven loading, resulting in a high rework rate. Moreover, the construction window is strictly limited by the weather.

[0026] Therefore, there is currently no mature in-situ, non-lifting bearing replacement solution for docks, which cannot simultaneously solve the problems of safety, accuracy, cost, and efficiency in dock maintenance. There is an urgent need to develop a safe and controllable method for replacing dock stern gate bearings that is free from dependence on large lifting equipment.

[0027] To achieve the above objectives, this application provides a method for replacing the bearing 44 of the main hinge 2 of the stern door of a ship docked at a wharf, comprising the following steps: S1 Support in place: Set up a support platform 5 in the area corresponding to the stern door 2 of the ship's berthing position at the dock, open the ship's stern door 2 and place it smoothly on the support platform 5, and loosen the traction steel wire rope 3 of the stern door 2 to a slack state. S2 reference locking: A limiting support fixture is installed at the hull 1 end of the main hinge 4 of the stern door 2. The limiting support fixture limits the relative position of the hinge at the hull 1 end and the hinge eye plate at the stern door 2 end, and the main hinge 4 at the hull 1 end remains in a non-disassembly state throughout the process. S3 Pre-processing disassembly and inspection: Remove the peripheral auxiliary structure of the main hinge 4 to fully expose the main shaft 45, the bearing 44 to be replaced and the bushing 46 of the main hinge 4, and complete the cleaning and condition inspection of the parts to be replaced. S4 Non-destructive Disassembly: Adjust the spatial posture of the hinge eye plates at both ends of the stern door by using a traction adjustment tool in conjunction with a hydraulic jacking tool. After calibrating the coaxiality of the four holes of the main hinge, remove the main shaft 45 and the old bearing 44 to be replaced from the hinge eye plates in sequence. S5 bearing 44 reinstallation: Clean the mounting surface of the hinge eye plate, lubricate the new bearing 44, and then use a special pressing tool and a hydraulic jacking tool to press the new bearing 44 smoothly into the designed installation position of the hinge eye plate, and calibrate the coaxiality of the new bearing 44 with the hinge at the 1 end of the hull. S6 Reset Acceptance: Insert the main shaft 45 into the inner hole of the new bearing 44, and then reset and install the bushing 46, sealing structure and peripheral auxiliary structure of the main hinge 4 in sequence. After completing the lubrication and installation accuracy verification, the replacement of the bearing 44 of the main hinge 4 of the stern door 2 is completed.

[0028] In a specific embodiment, taking the replacement of the bearing 44 of the main hinge 4 of the stern door 2 on an 8600-vehicle PCTC car carrier while it is docked at the pier as an example, the stern door 2 of this ship has a total weight of 260T and a total length of 50m. The main hinge 4 is the core rotary support structure for opening and closing the stern door 2. The specific implementation steps for replacing the bearing 44 of the stern door 2 are as follows: S1 Support in Place: In the area corresponding to the stern gate 2 of the ship berthing position at the dock, a modular rigid outfitting platform is set up as a support platform 5. The modular outfitting platform can be formed by welding steel sections, with a single module rated load of not less than 50T. It is arranged in an array along the length and width of the stern gate 2, and the total load-bearing capacity of the platform is not less than 320T (not less than 1.2 times the total weight of the stern gate 2). The top surface of the platform is equipped with an anti-slip buffer pad, and the platform can be reused for subsequent ship docking stage stern gate 2 commissioning operations.

[0029] During a stable zero-tide period, the stern gate 2 is opened slowly at a constant speed using its own hydraulic system, and then smoothly placed on the support platform 5. The attitude of the stern gate 2 is adjusted so that its overall levelness is controlled within 0.1 mm / m. After confirming that the force on each support point of the platform is uniform and there is no local overload, the traction steel wire rope 3 of the stern gate 2 is loosened to a completely slack state to eliminate the influence of the steel wire rope tension on the attitude of the stern gate 2, thus providing a stable static support foundation for subsequent operations.

[0030] S2 reference locking: A limiting support fixture is installed at the hull 1 end of the main hinge 4 of the stern door 2. The limiting support fixture includes a fixed seat at the hull 1 end, a rigid limiting block and a connecting rod. The fixed seat at the hull 1 end is rigidly connected to the base of the main hinge 4 of the hull 1 by high-strength bolts. The rigid limiting block is respectively clamped on both sides of the vertical and axial direction of the hinge eye plate at the stern door 2 end, and locked and fixed by the connecting rod, limiting the vertical and axial displacement of the hinge eye plate at the stern door 2 end to no more than 0.1mm.

[0031] Throughout the entire operation, the main hinge 4 at hull 1 remains in a non-disassembly state. The main hinge 4 at hull 1 serves as the sole positioning reference for the entire construction process. After the limit support fixture is installed, the limit clearance is checked with a feeler gauge to confirm that the fixture is not loose and the hinge does not move relative to each other. This prevents the reference from shifting during disassembly and assembly and ensures the coaxiality accuracy of subsequent disassembly and assembly operations.

[0032] S3 Pre-processing Disassembly and Inspection: Following the order from the outside to the inside, remove the peripheral structures of the main hinge 4. Specifically, first remove the end caps 41 on both sides of the main hinge 4, then remove the upper cover 42 of the hinge seat 47, and finally remove the split-type sealing cover (Half cover) of the bearing 44, fully exposing the main shaft 45 of the main hinge 4, the bearing 44 to be replaced, and the bushing 46. During the disassembly process, number and store all bolts, end caps 41, and seals according to their left and right sides and installation positions, and take precautions against dust and impacts to prevent the loss or damage of parts.

[0033] After dismantling, use a high-pressure clean air gun to clean the residual oil, iron filings and impurities in the hinge cavity. Wipe the mounting surface of the hinge eye plate and the mating surface of the main shaft 45 with anhydrous ethanol. Then, use an industrial endoscope to inspect the wear and jamming of the bearing 44 to be replaced, as well as the corrosion and scratches on the inner wall of the hinge eye plate. Record the inspection results, confirm that there is no structural damage that will affect the installation, and complete the cleaning and condition inspection of the parts to be replaced.

[0034] S4 Non-destructive Disassembly: Using a hand-operated hoist as a traction and adjustment tool and a hydraulic jack as a hydraulic jacking tool, firstly, vertical rigid support seats are installed vertically on the hinge eye plates at both ends of the stern door, along with two 100T vertical hydraulic jacks; then, axial rigid support seats are installed axially on the hinge eye plates, along with two 100T axial hydraulic jacks, and two 5T hand-operated hoists are used to slowly fine-tune the spatial attitude of the hinge eye plates. During the adjustment process, a feeler gauge is used to measure the fit clearance between the bushing 46 and the hinge hole in real time, and the coaxiality of the hull end 1 and the main hinge hole 4 at the stern door end 2 is calibrated, controlling the coaxiality within 0.05mm.

[0035] After coaxiality calibration, a special disassembly fixture for the main shaft 45 is installed. The fixture is coaxially fixed to the hinge eye plate with circumferential bolts. A guide rod adapted to the inner hole of the main shaft 45 is set at the center of the fixture to ensure coaxiality during the jacking process. Four 50T hydraulic jacks evenly distributed in a ring around the fixture push the end face of the main shaft 45 synchronously, and the main shaft 45 is pushed out of the hinge eye plate at a constant speed and removed. Throughout the process, the jacking force deviation of each jack is controlled to not exceed 1% to avoid bending of the main shaft 45 due to uneven load and scratches on the mating surfaces.

[0036] After the main shaft 45 is removed, a special disassembly tool for bearing 44 is replaced. Using the same coaxial pushing method, the outer ring end face of the old bearing 44 is pushed synchronously by a hydraulic jack to smoothly push the old bearing 44 to be replaced out of the hinge eye plate and remove it. After the old bearing 44 is removed, the mounting surface of the hinge eye plate is cleaned again and the dimensional accuracy of the mounting surface is checked to prepare for the reinstallation of the new bearing 44.

[0037] S5 bearing 44 reinstallation: First, use metallographic sandpaper to polish the hinge eye plate mounting surface to remove burrs, rust, and high wear points. Then, thoroughly clean the mounting surface with anhydrous ethanol to ensure that the surface is free of oil, impurities, and protrusions. This completes the cleaning process for the hinge eye plate mounting surface.

[0038] After re-inspecting the dimensional accuracy of the new bearing 44 and confirming that the dimensional tolerances of the inner and outer rings of the bearing 44 meet the design requirements, apply special waterproof lithium-based grease that matches the bearing 44 model evenly to the raceway and outer ring mating surfaces of the bearing 44. Ensure that the grease completely covers the raceway and rolling elements to complete the lubrication pretreatment of the new bearing 44.

[0039] A dedicated press-fit fixture for bearing 44 is installed. The fixture is coaxially fixed to the hinge eye plate and equipped with a coaxial guide assembly adapted to the inner bore of bearing 44. Using hydraulic jacks evenly distributed in a ring around the fixture, the outer ring end face of the new bearing 44 is synchronously pushed, pressing the new bearing 44 smoothly into the designed installation position on the hinge eye plate at a constant speed of 5 mm / min. During the press-fit process, the pushing force and displacement data are monitored in real time to prevent uneven loading and jamming. After press-fitting, a laser alignment instrument is used to calibrate the coaxiality between the inner bore of the new bearing 44 and the main hinge 4 at hull 1, confirming that the coaxiality meets the design accuracy requirements.

[0040] S6 Reset Acceptance: First, pre-process the spindle 45 by machining a 10mm transition radius at the insertion end of the spindle 45 and spraying a temporary lubricating coating to prevent scratching the inner ring and seal of the new bearing 44 during installation. Adjust the spindle 45's posture using a hand-operated hoist and jack to ensure that the spindle 45 and the inner hole of the bearing 44 are completely coaxial. Smoothly insert the spindle 45 into the inner hole of the new bearing 44. Simultaneously install the bushing 46 seal during installation. After installation, adjust the circumferential position of the shaft end clamping plate to ensure that the clamping plate and the bolt holes of the end cover 41 are completely aligned to avoid misalignment during subsequent installation.

[0041] After the spindle 45 is installed, the bushing 46, the bearing 44 sealing structure, the upper cover 42 of the hinge seat 47, and the left and right end covers 41 of the main hinge 4 are installed in sequence. All connecting bolts are tightened diagonally and evenly according to the design torque value. After tightening, sufficient special grease is added through the lubrication system of the main hinge 4, and a 10-minute pressure test is carried out to confirm that there is no leakage in the lubrication system and that the oil injection line is unobstructed.

[0042] Finally, the installation accuracy was checked and the performance was accepted: the coaxiality of the main hinge 4 and the rotation center accuracy of the stern door 2 were checked with a laser tracker to confirm that all dimensions met the design requirements; the stern door 2 underwent 23 full-stroke opening and closing cycle tests, and the bearing 44 was monitored throughout the process to ensure that there was no jamming, no abnormal noise, and no abnormal temperature rise. After all indicators passed the acceptance test, the replacement of the bearing 44 of the main hinge 4 of the stern door 2 was completed.

[0043] In summary, the method for replacing the main hinge 4 bearing 44 of the stern gate 2 of a vessel berthed at a dock, provided in this embodiment, eliminates the reliance on dry docks and large-tonnage floating cranes. The bearing 44 can be replaced on-site at the dock without the vessel entering the dry dock, significantly reducing maintenance costs and avoiding the risk of delays caused by tight dock schedules and uncontrollable floating crane availability. The support platform 5 provides static stability support for the stern gate 2 throughout its length, and in conjunction with the hull-1 end locking fixture, completely eliminates the significant safety risks associated with large-tonnage lifting operations. The impact of wind, waves, and severe weather on the construction process is greatly reduced, enhancing operational safety and the controllability of the operational window. Significant improvements have been made; through precise coaxiality calibration and synchronous jacking process using specialized tooling, non-destructive disassembly and assembly of the main shaft 45 and bearing 44 have been achieved, ensuring the installation accuracy of bearing 44 and avoiding problems such as hinge structure deformation and bearing 44 off-center load failure during disassembly and assembly. This has greatly improved maintenance quality and the service life of bearing 44. At the same time, the overall process is highly standardized, easy to operate, and the core tooling can be reused. No large-scale specialized equipment is required, and it can be directly applied to dock maintenance operations of stern door 2 and gangway hinge bearing 44 of various roll-on / roll-off ships and passenger roll-on / roll-off ships, combining excellent economy, safety and practicality.

[0044] In one embodiment, in step S1, the support platform 5 adopts a modular outfitting platform, and the load-bearing capacity of the modular outfitting platform is not less than 1.2 times the total weight of the stern door 2.

[0045] Based on the total weight of stern door 2, the overall rated static load capacity of the platform is set to be no less than 1.2 times the total weight of stern door 2. Taking an 8600-vehicle PCTC car carrier as an example, the minimum rated load capacity of the platform in this embodiment is no less than 312T. The platform adopts a modular outfitting platform structure. Each module is made of Q355B low-alloy high-strength steel welded into a box-type frame structure. The standard module dimensions are 2m × 3m × 1.2m. The frame is internally reinforced with interlaced stiffeners, with a stiffener thickness of no less than 16mm. The rated static load of a single module is... With a load capacity of no less than 60T, this embodiment is equipped with 6 standard load-bearing modules + 2 auxiliary leveling modules, and the overall rated load capacity after combination reaches 360T, meeting the safety factor requirement of more than 1.2 times. Each module is equipped with 4 sets of adjustable spiral legs at the bottom, with an adjustment stroke of 0-200mm to adapt to the unevenness of the dock ground. The bottom of the legs is equipped with 10mm thick steel plate pads and 20mm thick rubber anti-slip pads to control the pressure of the platform on the ground within the allowable pressure range of the dock ground, avoiding ground settlement and platform instability during construction.

[0046] This embodiment avoids the risk of overload instability of the large-tonnage stern gate 2 support from the design source by setting a load-bearing safety factor of no less than 1.2 times the total weight of the stern gate 2. At the same time, the modular structure can be flexibly adapted to different specifications of stern gate 2 and dock conditions, and is convenient to disassemble, transport and reuse, which greatly reduces the tooling manufacturing cost. The 1.2 times safety redundancy also fully offsets the additional load caused by load fluctuations and tidal changes during construction, further improving the safety and stability of the operation.

[0047] In one embodiment, in step S2, the limiting support fixture includes a fixed seat at the hull end 1 and a hinge limiting block. The fixed seat at the hull end 1 is rigidly connected to the base of the main hinge 4 of the hull end 1. The hinge limiting block restricts the vertical and axial displacement of the hinge eye plate at the stern door end 2 to no more than 0.1 mm, with the main hinge 4 at the hull end 1 serving as the positioning reference for the entire construction process.

[0048] Specifically, the limiting support fixture in this embodiment is formed by heat-treated 45# steel and consists of two core components: a fixed seat at the hull 1 end and a hinge limiting block. The fixed seat at the hull 1 end is an L-shaped rigid bearing seat. The base plate has through holes that perfectly match the existing mounting bolt holes of the main hinge 4 base of the hull 1. It is rigidly connected to the base using 12.9 grade high-strength bolts, eliminating the need for additional drilling or welding on the hull 1 structure and avoiding damage to the hull 1's structural integrity. The fixed seat's upright plate has multiple adjustable mounting holes to accommodate the limiting adjustment requirements of hinges of different specifications. Triangular reinforcing ribs are welded between the upright plate and the base plate to ensure the overall rigidity of the fixture, with structural deformation not exceeding 0.02mm under rated load. The hinge limiting blocks are divided into two sets: vertical limiting blocks and axial limiting blocks. Each set is equipped with a pair of limiting units: the vertical limiting blocks are respectively locked on the upper and lower sides of the hinge eye plates at both ends of the stern door to limit the vertical displacement of the eye plates; the axial limiting blocks are respectively locked on the front and rear axial sides of the hinge eye plates to limit the axial movement of the eye plates along the hinge axis; all the contact surfaces between the limiting blocks and the hinge eye plates are covered with 3mm thick polyurethane wear-resistant pads, which not only avoids rigid contact from scratching the anti-corrosion coating and mating surfaces of the hinge eye plates, but also allows for precise adjustment of the limiting gap by replacing pads of different thicknesses.

[0049] This embodiment uses a fixed base rigidly connected to the main hinge 4 base of hull 1, combined with a precise limiting stop structure, to strictly control the displacement of the hinge eye plate within 0.1mm. This completely avoids the risk of hinge movement and reference offset at the stern door 2 end during the disassembly and assembly of bearing 44. At the same time, the main hinge 4 at the hull 1 end, which is not disassembled throughout the process, is used as the only fixed reference, ensuring the coaxiality accuracy throughout the disassembly and reassembly process. The tooling does not require hot work or drilling into the hull 1 structure, making installation convenient and allowing for repeated adaptation to the same type of ship hinges, greatly improving the safety and installation accuracy of construction.

[0050] In one embodiment, in step S3, the dismantling sequence of the peripheral auxiliary structures is as follows: the end caps 41 on the left and right sides of the main hinge 4, the upper cover 42 of the hinge seat 47, and the bearing seal cover 43 are removed in sequence. During the dismantling process, each component is numbered and protected to prevent bolts and seals from being lost or damaged.

[0051] Specifically, before construction, preparatory work should be completed. A high-altitude work platform with guardrails should be erected below the main hinge 4 working area. An integrated anti-fall oil receiving tray should be set up directly below the hinge to prevent parts from falling and oil from contaminating the hull 1 structure during dismantling. Non-destructive dismantling tools such as nylon hammers, copper rods, torque wrenches, and special pry bars should be prepared. Debris and oil stains around the main hinge 4 should be cleaned in advance. An isolation and protection zone should be set up in the working area to avoid interference from irrelevant personnel.

[0052] Demolition work must be carried out in the following fixed sequence: S31 Remove the end caps 41 on both sides of the main hinge 4: The end caps 41 are axial limiting components of the main shaft 45 of the main hinge 4. They are rigidly connected to the end face of the hinge eye plate using 12.9 grade high-strength flange bolts. When removing them, loosen all the bolts gradually in a diagonal cycle to avoid unilateral force causing warping and deformation of the end caps 41 and damage to the threads. After the bolts are completely loosened, use a nylon hammer to evenly tap the end caps 41 circumferentially to separate them from the mating surface. Then, use a pre-installed hand chain hoist to remove them smoothly to prevent the end caps 41 from falling and being bumped.

[0053] S32 Remove the upper cover 42 of the hinge seat 47: The upper cover 42 of the hinge seat 47 is a load-bearing protective cover plate covering the upper cavity of the main hinge 4. After removing the end cover 41, the upper cover has no interference from the surrounding structure and the upper working space can be opened directly. When removing it, first loosen the fastening bolts of the upper cover diagonally. After loosening, use a hand hoist to assist in hoisting and remove the upper cover smoothly to avoid deformation of the cover plate. After removal, clean the residual oil and impurities in the upper cavity of the hinge seat 47 at the same time to provide a clean working environment for the subsequent removal of the bearing sealing cover 43 and prevent debris from falling into the mating cavity of the bearing 44.

[0054] S33 Removal of bearing seal cover 43: The bearing seal cover 43 is a split-type seal cover that wraps around the outer ring of the bearing 44. It is the core sealing component that directly fits the bearing 44. Removing it last can prevent impurities and oil stains from entering the mating surface of the bearing 44 during the previous removal work and protect the precision mating surface of the hinge eye plate inner hole. When removing it, first remove the circumferential fastening bolts of the seal cover, and use a copper rod to gently tap the separation surface of the seal cover evenly along the circumference to make the two halves of the seal cover separate smoothly from the mating surface. Remove the upper and lower halves of the seal cover in sequence, and avoid scratching the outer ring of the bearing 44 and the mating surface of the sealing groove during the entire process.

[0055] This embodiment avoids structural interference, component warping and deformation, and contamination of precision mating surfaces during the dismantling process by setting a standardized dismantling sequence. At the same time, the one-to-one numbered protection measures throughout the process completely avoid the situation of incorrect assembly, omission, and mixed bolts, which greatly improves the efficiency and standardization of dismantling operations, reduces the risk of human error, protects the fitting accuracy and sealing performance of each component, and lays a reliable quality foundation for the subsequent disassembly, assembly, and reassembly of bearing 44.

[0056] In one embodiment, in step S4, when adjusting the attitude of the hinge eye plate, a feeler gauge is used to measure the fit clearance between the bushing 46 and the hinge hole in real time, and a bidirectional limit adjustment is performed by using a rigid support seat in the vertical and axial directions in conjunction with a hydraulic jack; when removing the main shaft 45 and the old bearing 44, a special disassembly tooling is used that is coaxially fixed with the hinge eye plate, and a ring of evenly distributed hydraulic jacks is used to push synchronously to ensure that there is no off-center load during the pushing process.

[0057] The specific implementation details are as follows: S41 Two-Way Rigid Support System Installation: First, construct a rigid support and adjustment system with vertical and axial bidirectional limiting. The vertical rigid support base is made of Q355B low-alloy high-strength steel, machined into a box-shaped structure with anti-slip grooves. It is symmetrically installed in two groups, upper and lower, between the main hinge 4 base of hull 1 and the hinge eye plate at the stern door 2. Each support base is equipped with one double-acting self-locking hydraulic jack with a rated load of 100T. The jack's pushing surface is completely in contact with the support base, forming a vertical bidirectional adjustment system. The axial rigid support base is rigidly fixed on the hull 1 end fixing base installed in step S2. It is arranged symmetrically in two groups, front and rear, along the hinge axis. Each group is equipped with one double-acting self-locking hydraulic jack with a rated load of 100T. The jack's pushing end is in contact with the axial end face of the hinge eye plate, forming a front and rear bidirectional adjustment system along the hinge axis.

[0058] S42 Real-time Measurement and Precise Attitude Fine-tuning of Gap: A circumferential fixed-point graded measurement method is adopted. Four fixed measuring points (upper, lower, left, and right) are evenly set along the inner circumference of the hinge hole. A standard feeler gauge with specifications of 0.02mm, 0.05mm, and 0.1mm is used at each measuring point to measure the fit clearance between the bushing 46 and the hinge hole step by step, and the clearance value of each measuring point is recorded in real time. Adjustment follows the principle of "vertical first, then axial, step-by-step fine-tuning, and real-time re-measurement": First, the vertical attitude of the hinge eye plate is adjusted by the synchronous extension and retraction of the vertical jacks to eliminate the gap difference between the upper and lower measuring points; then, the axial position of the hinge eye plate is adjusted by the synchronous extension and retraction of the axial front and rear jacks to eliminate axial movement; after each fine-tuning, the gap of the four measuring points is re-measured with a feeler gauge. This cycle of adjustment is repeated until the gap difference of each measuring point in the circumferential direction of the hinge hole is controlled within 0.05mm, and the coaxiality of the four main hinge holes at hull end 1 and stern door end 2 is calibrated to within 0.05mm.

[0059] S43 Rigid Attitude Locking: After the attitude adjustment meets the standard, lock the self-locking valves of all hydraulic jacks. At the same time, insert stainless steel fixing shims that match the thickness of the gap into the fit gap between the rigid support seat and the hinge eye plate and the base to form a rigid mechanical lock. This completely avoids jack pressure leakage, attitude rebound, and hinge eye plate displacement during construction, providing a stable and unchanging coaxial reference for subsequent disassembly operations.

[0060] Dedicated coaxial disassembly fixtures are provided for both the main spindle 45 and the old bearing 44, all machined from 45# quenched and tempered steel. The main spindle 45 disassembly fixture includes a coaxial fixing flange, a guide mandrel, and an annular push plate. The coaxial fixing flange has through holes that perfectly match the original mounting bolt holes on the hinge eye plate end face. It is rigidly connected to the hinge eye plate end face using 12.9 grade high-strength bolts, ensuring that the coaxiality deviation between the fixture and the hinge hole does not exceed 0.02mm. The guide mandrel passes through the central inner hole of the main spindle 45 and slides with the guide sleeve at the center of the fixing flange, providing full coaxial guidance during the pushing process and preventing the main spindle 45 from deviating. The bearing 44 disassembly fixture has the same core structure as the main spindle 45 fixture, except that the annular push plate is replaced with a dedicated push ring that perfectly fits the outer ring end face of the bearing 44. The push ring only rigidly contacts the outer ring of the bearing 44, avoiding damage to the rolling elements and cage of the bearing 44 during the pushing process and preventing the bearing 44 from breaking and scratching the inner hole of the hinge eye plate.

[0061] During the disassembly of the main spindle 45, the synchronous hydraulic pump station was started, and the spindle was pushed at a constant low speed. Throughout the process, the displacement of the main spindle 45 and bearing 44 was monitored in real time using four dial indicators evenly arranged circumferentially. If the displacement difference between the measuring points in the circumferential direction exceeded 0.03mm, the machine was stopped immediately for adjustment to eliminate the off-center load before continuing the operation. During the pushing process, the mating surfaces were continuously cleaned with a high-pressure clean air gun to prevent iron filings and impurities from scratching the precision mating surfaces, until the main spindle 45 and the old bearing 44 were smoothly pushed out of the hinge eye plate and completely removed. After disassembly, the inner hole of the hinge eye plate was cleaned again, and the dimensional accuracy of the inner hole and the surface damage were checked to prepare for the subsequent reinstallation of the new bearing 44.

[0062] This embodiment precisely calibrates the coaxiality of the hinge hole by using a combination of vertical and axial bidirectional rigid support and real-time measurement with feeler gauges for fine-tuning. This completely avoids problems such as spindle 45 jamming and scratches on mating surfaces caused by posture deviation during disassembly. At the same time, a special tooling fixed coaxially with the hinge eye plate, along with evenly distributed synchronous hydraulic jacks in a ring, enables uniform speed and non-eccentric load disassembly of the spindle 45 and bearing 44. This allows for non-destructive operation throughout the process, avoiding irreversible damage such as plastic deformation of the hinge eye plate and bending of the spindle 45 caused by violent disassembly. This significantly improves the accuracy and safety of the disassembly operation, reduces the risk of rework, and lays a reliable foundation for the high-precision reinstallation of the new bearing 44.

[0063] In one embodiment, in steps S5 and S6, before the new bearing 44 is press-fitted, the dimensional accuracy and cleanliness of the inner hole and outer ring of the bearing 44 need to be checked. The lubrication pretreatment uses a special grease that matches the bearing 44 model to fill the entire raceway. Before the spindle 45 is installed, a transition fillet of R10mm needs to be machined at the end of the spindle 45. During the installation process, the bushing 46 sealing ring is installed simultaneously. After the installation is completed, the circumferential position of the shaft end plate is adjusted to ensure that it is coaxially aligned with the bolt hole of the end cover 41.

[0064] This embodiment avoids the installation of substandard bearings by conducting full dimensional and cleanliness inspections before press-fitting the new bearing 44, ensuring the accuracy of the fit between the bearing 44 and the mating surfaces. The application of dedicated grease for the entire raceway is fully adapted to heavy-duty marine conditions, preventing early failure due to poor lubrication of the bearing 44 and significantly extending its service life. The refined machining of the R10mm transition radius at the end of the main shaft 45 completely eliminates the risk of scratches on the inner ring and seal of the bearing 44 during installation. The simultaneous installation of the seal prevents damage to the seal flanges, ensuring the protective performance of the sealing system and preventing corrosion failure of the bearing 44 caused by seawater and impurities. The precise alignment and adjustment of the shaft end clamp prevents rework due to misaligned holes during the subsequent installation of the end cover 41, significantly improving the efficiency and standardization of the reinstallation operation. Overall, this embodiment achieves high-precision, non-destructive, and full-process quality control for the installation of the bearing 44, significantly improving the long-term operational reliability of the stern door 2 main hinge 4.

[0065] In one embodiment, in step S1, the support platform 5 adopts an array-type hydraulic servo support platform 5. The array-type hydraulic servo support platform 5 integrates a load sensor, a displacement sensor and a tide level linkage control unit. During the construction process, the tide level changes and the attitude data of the hull 1 are collected in real time, and the lifting displacement and load of each support point are dynamically adjusted to keep the relative position deviation between the stern door 2 and the main hinge 4 at the end of the hull 1 not exceeding 0.5mm throughout the process.

[0066] Specifically, as an optional implementation of the array-type hydraulic servo support platform 5 used in this embodiment, it adopts a modular distributed array structure. The core consists of four parts: eight independent servo support units, a main control cabinet, a tide level linkage control unit, and a data acquisition module. It is fully adaptable to the load-bearing and attitude control requirements of the 260T stern gate 2, including: Along the main load-bearing longitudinal beams after the stern door 2 is opened, eight independent servo support units are arranged in an array of two rows and four columns. The core of each unit includes a double-acting self-locking servo hydraulic cylinder with a rated load of 50T, a spoke-type load sensor (measurement accuracy 0.5%FS), a magnetostrictive displacement sensor (measurement accuracy ±0.01mm), and an integrated hydraulic lock valve group. The bottom of the unit is equipped with a steel plate pad with anti-slip rubber pads to adapt to the unevenness of the dock surface, and the top is equipped with a 20mm thick Shore hardness 60 buffer pad to avoid rigid contact with the steel structure of the stern door 2, which would cause coating scratches and structural impacts. The total rated load of the eight units combined reaches 400T, which is more than 1.5 times the total weight of the stern door 2, with sufficient safety redundancy.

[0067] The core of the tide level linkage control unit is a PLC main control module with closed-loop calculation function, which is equipped with a wharf real-time tide level acquisition module, a dual-axis hull 1 attitude sensor (measurement accuracy 0.001°), a high-precision laser ranging module, an industrial touch screen and a wireless communication unit. The tide level acquisition module can be connected to the wharf tide level monitoring station to obtain real-time tide level data and forecast data every minute. The hull 1 attitude sensor is fixed at the base of the main hinge 4 at the stern of hull 1 to collect the longitudinal, transverse, and heave data of hull 1 in real time. The laser ranging module is installed at the corresponding positions of the main hinge 4 at the hull 1 end and the stern door 2 end to collect the relative position deviation between the two in real time. All data are synchronously connected to the main control module to realize linkage calculation.

[0068] Before platform construction, based on the center of gravity distribution of stern door 2 and the position of the main load-bearing structure, the array positioning of 8 sets of servo support units was completed. The units were networked through wired communication to complete the synchronization debugging, sensor calibration and communication debugging under no-load conditions, ensuring that the synchronization error of all unit actions does not exceed 10ms. After debugging, stern door 2 was slowly lowered to the top surface of support platform 5 through the stern door 2 opening and closing system. During the descent, the main control unit collected the load data of each unit in real time and dynamically fine-tuned the lifting height of each cylinder to make stern door 2 land smoothly. After landing, the load deviation of each support unit was controlled within ±5%, with no local overload. After confirming that the attitude of stern door 2 was stable, the traction steel wire rope 3 was loosened to a completely slack state. The initial relative position of the main hinge 4 at the hull 1 end and stern door 2 was calibrated using a laser tracker and set as the reference zero point for the entire construction process. At the same time, a control threshold of relative position deviation ≤0.5mm was set.

[0069] Throughout the entire construction process (from the placement of stern gate 2 to the completion of bearing 44 replacement and before stern gate 2 is reset), the platform maintains the tide level-linked dynamic compensation mode and executes the following closed-loop control process: Multi-source real-time data acquisition: The tide level acquisition module acquires real-time data on changes in the tidal level at the dock. The attitude sensor of hull 1 synchronously acquires data on the heave, pitch, and roll of hull 1 caused by the rise and fall of the tide. The laser ranging module acquires the three-dimensional relative position deviation between the stern gate 2 and the main hinge 4 at the end of hull 1 in real time. The load and displacement sensors of each support unit synchronously acquire real-time load and lifting height data. All data are synchronously transmitted to the tide level linkage control unit at a frequency of 1 time / second.

[0070] Coupling calculation and compensation calculation: Based on the collected multi-source data, the main control module completes the coupling calculation of tide level, hull 1 attitude, stern gate 2 displacement and support load, accurately calculates the relative displacement of hull 1 and support platform 5 caused by tide level changes, as well as the lifting displacement and load control threshold that each support unit needs to adjust, to ensure that the relative position of stern gate 2 and hull 1 end main hinge 4 after adjustment always fits the initial reference zero point.

[0071] Synchronous dynamic adjustment and closed-loop control: The main control module sends adjustment commands to each servo support unit, and all units synchronously execute lifting / lowering actions, adjusting smoothly at a low speed of ≤1mm / s. During the adjustment process, displacement and load data are transmitted back in real time, forming a closed-loop feedback. When the tide rises and the hull 1 floats, the corresponding support unit synchronously lifts to compensate for the displacement. When the tide falls and the hull 1 sinks, the corresponding support unit synchronously lowers to release the displacement, ensuring that the relative position deviation between the stern door 2 and the main hinge 4 at the end of the hull 1 does not exceed 0.5mm throughout the process. At the same time, the load of each unit is monitored in real time to avoid situations where the stern door 2 is partially suspended or overloaded.

[0072] Safety Redundancy Management: The system is equipped with a dual-level safety threshold. When the relative position deviation reaches 0.3mm, an early warning is triggered. When the deviation approaches 0.5mm, the adjustment frequency is automatically increased and unnecessary operations are locked. It is also equipped with a power failure self-locking protection function. In the event of a sudden power failure, the hydraulic locking valve group immediately locks the oil cylinder to maintain the current support state and prevent the stern door 2 from becoming unstable. For critical operations such as bearing 44 disassembly and press-fitting, the system automatically switches to high-precision mode to tighten the relative position deviation to ≤0.2mm, providing a higher precision benchmark guarantee for core operations.

[0073] Full-process data traceability: The system automatically stores tide data, hull attitude data, support unit displacement and load data, and relative position deviation data throughout the entire construction cycle, generating traceable construction record reports that meet the quality control requirements for ship construction and maintenance.

[0074] This embodiment solves the core problems of traditional fixed support platforms 5, such as the impact of tidal fluctuations and the relative positional misalignment between the hull 1 and the stern gate 2, by integrating an array-type hydraulic servo support platform 5 with integrated tidal level linkage control. It breaks the limitation of the original solution, which can only be constructed during the narrow window period of zero tide, and enables uninterrupted operation of the dock around the clock, significantly shortening the construction cycle. The closed-loop dynamic adjustment throughout the process strictly controls the relative positional deviation between the stern gate 2 and the main hinge 4 at the end of the hull 1 within 0.5mm, ensuring the stability of the coaxiality reference throughout the assembly and disassembly of the bearing 44. This fundamentally avoids problems such as jamming of the main shaft 45, scratches on mating surfaces, and structural deformation caused by reference misalignment. At the same time, real-time load balancing control avoids irreversible structural damage caused by local overload of the stern gate 2, greatly improving the safety and stability of the operation. Moreover, the modular array structure can be flexibly adapted to stern gates 2 of different tonnages and specifications, and the tooling has a high reusability rate, making it highly adaptable to various scenarios and of great value for industry promotion.

[0075] In one embodiment, in steps S4 and S5, when the old bearing 44 is stuck, a medium-frequency induction heating fixture is used to uniformly heat the outer ring of the bearing 44 in a ring. The heating temperature is controlled at 80-120°C. After eliminating the interference, non-destructive disassembly is completed. Before pressing the new bearing 44, a deep cryogenic treatment process is used to cool the new bearing 44 to -40°C to -60°C and keep it at that temperature for 2-4 hours. This allows the outer ring of the bearing 44 to shrink and eliminate the interference before pressing.

[0076] This embodiment addresses the challenge of disassembling a stuck old bearing 44 by employing a medium-frequency annular uniform heating process with precise temperature control between 80-120℃. This process not only rapidly eliminates interference fit through uniform thermal expansion, achieving non-destructive disassembly of the stuck bearing 44, but also strictly avoids the risks of thermal deformation of the hinge eye plate and damage to surrounding components caused by high temperatures, completely preventing irreversible structural damage caused by violent cutting or hammering. For the pain point of press-fitting bearings 44 with large interference fit, a programmable deep cryogenic treatment process at -40℃ to -60℃ is used, through uniform cooling of the outer ring of bearing 44... The process completely eliminates interference fit, achieving stress-free and stable press-fitting. This avoids problems such as damage to the bearing raceway, cage deformation, and scratches on the mating surfaces during press-fitting, significantly improving the installation accuracy and first-pass yield of bearing 44. Both processes are closed-loop precise control, adapted to the dockside operating environment. This not only solves the problem of disassembling and assembling bearing 44 under extreme working conditions, but also ensures the installation quality and long-term operational reliability of bearing 44 from the source, greatly reducing the maintenance rework rate and effectively extending the service life of bearing 44 in the stern door 2 main hinge 4.

[0077] In one embodiment, in steps S2, S4, and S5, a high-precision laser reference target is set on the base of the main hinge 4 at the hull 1 end. The coaxiality and parallelism data of the hinge hole are collected in real time by a laser tracker and a vision alignment system. With the help of a six-degree-of-freedom adjustment fixture, the closed-loop automatic adjustment of the hinge eye plate attitude is realized, and the coaxiality control accuracy is not less than 0.01mm.

[0078] This embodiment establishes a unique and stable benchmark throughout the entire construction process using a laser reference target fixed at one end of the hull. Combined with multi-source fusion measurement using a laser tracker and a vision alignment system, and a six-degree-of-freedom tooling, it achieves fully closed-loop automatic adjustment of the hinge eyeplate attitude. This improves the coaxiality control accuracy from the traditional 0.1mm level to the 0.01mm level, completely eliminating reliance on manual operation experience and removing inherent errors from manual measurement and adjustment. Simultaneously, real-time monitoring and dynamic deviation compensation are implemented throughout the entire process of benchmark locking, bearing 44 disassembly, and reassembly, ensuring the consistency and stability of the benchmark throughout the construction process. This fundamentally avoids problems such as main shaft 45 jamming, mating surface scratches, and bearing 44 off-center pressure failure caused by benchmark offset. It significantly improves the efficiency and installation accuracy of bearing 44 disassembly and assembly, effectively extending the service life of the stern door 2 main hinge 4 bearing 44. Furthermore, the entire process data is traceable, fully meeting the high-precision quality control requirements of high-end ship construction and maintenance.

[0079] In one embodiment, in step S6, after the installation accuracy verification is completed, in-situ performance verification is carried out, including static detection of the coaxiality of the main hinge 4, dynamic test of the full stroke opening and closing of the stern door 2, temperature rise and vibration detection of the bearing 44, and pressure holding test of the lubrication system. The final acceptance is completed after all indicators meet the design requirements.

[0080] This embodiment conducts in-situ full-item verification across four dimensions: static accuracy, dynamic operation, bearing 44 working status, and sealing reliability. This allows for comprehensive identification of hidden defects in bearing 44 installation within a dockside setting, preventing issues such as bearing 44 misalignment, jamming, seal failure, and poor lubrication from the outset. This avoids sudden malfunctions and unplanned downtime after ship operation. The full-item verification does not require the ship to enter dry dock, thus not occupying additional dockside resources. It achieves closed-loop control of maintenance quality, fully complying with classification society inspection requirements. This ensures the long-term safety and reliability of the stern door 2 main hinge 4, significantly reducing subsequent ship maintenance costs and failure risks. Furthermore, it can be directly applied to the acceptance phase of stern door 2 / slope maintenance for various ro-ro and passenger ro-ro ships, demonstrating strong industry versatility.

[0081] In the description herein, it should be understood that the terms "upper," "lower," "left," "right," and other orientations or positional relationships are used only for ease of description and simplification of operation, and 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 of this application. Furthermore, the terms "first" and "second" are used merely for descriptive distinction and have no special meaning.

[0082] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0083] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0084] The technical principles of this application have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this application without inventive effort, and these embodiments will all fall within the scope of protection of this application.

Claims

1. A method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf, characterized in that, Includes the following steps: S1 Support in place: Set up a support platform in the area corresponding to the stern door of the ship's berthing position at the dock, open the ship's stern door and place it smoothly on the support platform, and loosen the traction steel cable of the stern door to a slack state. S2 reference locking: A limiting support fixture is installed at the hull end of the stern door main hinge. The limiting support fixture limits the relative position of the hull end hinge and the stern door end hinge eye plate, and the hull end main hinge remains in a non-disassembly state throughout the entire process. S3 Pre-processing Disassembly and Inspection: Remove the peripheral auxiliary structures of the main hinge to fully expose the main shaft, bearing to be replaced and bushing of the main hinge, and complete the cleaning and condition inspection of the parts to be replaced. S4 Non-destructive Disassembly: The spatial orientation of the stern door hinge eye plate is adjusted by using a traction adjustment tool in conjunction with a hydraulic jacking tool. After calibrating the coaxiality of the main hinge hole, the main shaft and the old bearing to be replaced are pushed out and removed from the hinge eye plate in sequence. S5 bearing reinstallation: Clean the mounting surface of the hinge eye plate, lubricate the new bearing, and then use a special pressing tool and a hydraulic jacking tool to press the new bearing smoothly into the designed installation position of the hinge eye plate, and calibrate the coaxiality of the new bearing with the hull end hinge. S6 Reset Acceptance: Insert the main shaft into the inner hole of the new bearing, and then reset and install the bushing, sealing structure and peripheral structures of the main hinge in sequence. After completing the lubrication and installation accuracy verification, the replacement of the stern door main hinge bearing is completed.

2. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In step S1, the support platform adopts a modular outfitting platform, and the load-bearing capacity of the modular outfitting platform is not less than 1.2 times the total weight of the stern door.

3. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In step S2, the limiting support fixture includes a hull end fixed seat and a hinge limiting block. The hull end fixed seat is rigidly connected to the hull main hinge base. The hinge limiting block restricts the vertical and axial displacement of the stern door end hinge eye plate to no more than 0.1mm, with the hull end main hinge as the positioning reference for the entire construction process.

4. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In step S3, the dismantling sequence of the peripheral auxiliary structures is as follows: the end caps on the left and right sides of the main hinge, the hinge seat cover, and the bearing seal cover are removed in sequence. During the dismantling process, each component is numbered and protected to prevent the loss or damage of bolts and seals.

5. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In step S4, when adjusting the hinge eye plate posture, a feeler gauge is used to measure the fit clearance between the bushing and the hinge hole in real time, and a two-way limit adjustment is performed by using a rigid support seat in the vertical and axial directions in conjunction with a hydraulic jack; when removing the main shaft and the old bearing, a special disassembly tooling is used that is fixed coaxially with the hinge eye plate, and a ring of evenly distributed hydraulic jacks is used to push synchronously to ensure that there is no off-center load during the pushing process.

6. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In steps S5 and S6, before the new bearing is press-fitted, the dimensional accuracy and cleanliness of the bearing's inner hole and outer ring must be checked. For lubrication pretreatment, a special grease matching the bearing model is used to fill the entire raceway. Before the spindle is installed, a 10mm transition fillet needs to be machined at the end of the spindle. During the installation process, the bushing seal ring is installed simultaneously. After installation, the circumferential position of the shaft end clamp is adjusted to ensure that it is coaxially aligned with the end cover bolt hole.

7. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In step S1, the support platform adopts an array-type hydraulic servo support platform. The array-type hydraulic servo support platform integrates load sensors, displacement sensors and tide level linkage control units. During construction, it collects tide level changes and ship attitude data in real time, dynamically adjusts the lifting displacement and load of each support point, and keeps the relative position deviation between the stern door and the main hinge at the end of the ship no more than 0.5mm throughout the process.

8. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In steps S4 and S5, when the old bearing is stuck, a medium-frequency induction heating fixture is used to uniformly heat the outer ring of the bearing in a ring. The heating temperature is controlled at 80-120℃. After eliminating the interference fit, non-destructive disassembly is completed. Before pressing the new bearing, a deep cryogenic treatment process is used to cool the new bearing to -40℃~-60℃ and keep it at that temperature for 2-4 hours. This allows the outer ring of the bearing to shrink and eliminate the interference fit before pressing.

9. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In steps S2, S4, and S5, a high-precision laser reference target is set on the main hinge base at the hull end. The coaxiality and parallelism data of the hinge holes are collected in real time by a laser tracker and a vision alignment system. With the help of a six-degree-of-freedom adjustment fixture, the closed-loop automatic adjustment of the hinge eye plate attitude is achieved, and the coaxiality control accuracy is not less than 0.01mm.

10. The method for replacing the main hinge bearing of the stern gate of a ship docked at a wharf according to claim 1, characterized in that, In step S6, after the installation accuracy verification is completed, in-situ performance verification is carried out, including static testing of the main hinge coaxiality, dynamic testing of the stern door's full-stroke opening and closing, testing of bearing temperature rise and vibration, and testing of the lubrication system pressure holding. Final acceptance is completed after all indicators meet the design requirements.

Images