Construction method of newly-added ship stern side thruster device and side thruster subassembly module

Abstract

The application discloses a kind of new ship stern side thrust device construction method and small group erection module.The method comprises the following steps of S1, designing small group erection module;S2, preassembling side thrust cylinder body and part stern fin structure into integral module in workshop;S3, cutting installation port at predetermined position of ship body;S4, transporting module to ship bottom and hoisting into position by lifting device;S5, welding and fixing after adjusting alignment.Small group erection module is precisely positioned by opening U-shaped notch cooperating with cylinder body reinforcing flat iron in bottom frame.The present application converts a large number of on-site bulk work into workshop prefabrication, improves construction precision, welding quality and efficiency, shortens the shipbuilding berth / dock period, reduces the risk of high-altitude work and the influence of construction on ship body, and is suitable for the installation of stern side thrust in new shipbuilding and modification.

Description

Technical Field

[0001] This invention relates to the field of ship conversion technology, specifically to a method for constructing a new stern thruster device for a ship and a thruster assembly module. Background Technology

[0002] Side thrusters (also known as stern thrusters) are important equipment for enhancing a ship's maneuverability, especially when navigating at low speeds, berthing or unberthing at docks, or in narrow waters. For some ships that were not initially designed with stern thrusters, or that need to add stern thrusters according to operational requirements (such as some engineering vessels, research vessels, and cruise ships), modifications need to be made to the existing hull structure to install them.

[0003] Traditional methods for adding stern thrusters to ships typically involve on-site assembly. During construction, a large opening is first made at the predetermined location on the stern fin. The thruster cylinder structure is then hoisted into the opening, and the internal structures, such as the hull frame and ribs, connected to the cylinder are installed, positioned, and welded on-site one by one. Adding stern thrusters is often a dockside project, and because it's a modification, the dock period is generally short, leaving little time for construction. Completing it within a short timeframe is a major challenge. Furthermore, based on the drawings and analysis of previous construction methods, the following difficulties exist: 1. Before the side thruster is installed, how to install it in place by dismantling the old tail fin structure? According to conventional construction, the side thruster is dismantled into an ellipse on the left and right upper openings of the tail fin outer plate according to the diameter of the cylinder. The lower opening is affected by the motor base and cylinder reinforcement ring exceeding the cylinder diameter. In addition, the cylinder reinforcement ring exceeds the FR10 and FR12 frames, requiring more original ship structure to be dismantled and restored later. This results in a complicated dismantling and installation project with low efficiency and a long construction period.

[0004] 2. How to hoist the side thruster into place. Since the height of the motor base at the top of the side thruster cylinder exceeds the bottom plate of the ship, it is generally hoisted upwards from the side of the tail fin using a hand chain hoist, and then pulled diagonally to the installation position from the other side of the tail fin using another hand chain hoist. This method has extremely limited hoisting space, is difficult to position accurately, cannot guarantee safety, and is extremely inefficient.

[0005] 3. Directly cutting, installing, and welding on the tail fin results in limited operating space, inconvenient internal cutting and welding, high safety risks, and long operation time.

[0006] Therefore, a new stern thruster construction scheme is needed that can shorten the docking period, improve construction efficiency and safety, and ensure installation accuracy. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects in the existing technology and provide a construction method for adding a new ship stern thruster device.

[0008] To achieve the above objectives, one technical solution of the present invention is to design a construction method for adding a stern thruster device to a ship, comprising the following steps: S1: Design a sub-assembly module based on the ship's construction drawings and the dimensions of the stern thruster hull structure and the installation position of the thruster; based on the original ship's construction drawings, the detailed dimensions of the newly added stern thruster hull structure and its precise installation position on the stern fin, conduct a detailed design of the sub-assembly module. This design needs to determine the scope of the module, that is, including the hull structure and the stern fin structure that must be connected to it.

[0009] S2: Pre-assemble the cylindrical structure of the stern thruster and the stern fin structure including the first, second, and third skeletons into a single small assembly module; according to the design drawings in step S1, pre-assemble and weld the cylindrical structure of the stern thruster and the remanufactured first, second, and third skeletons and other stern fin structures into a single small assembly module with a complete structure and sufficient rigidity.

[0010] S3: At the predetermined installation position at the stern of the ship, cut and remove the corresponding stern fin structure of the original ship along the outer contour line of the sub-assembly module; at the predetermined side thruster installation position at the stern of the ship, according to the outer contour shape and size of the sub-assembly module, make precise lines on the stern fin structure of the hull, and then use plasma cutting, laser cutting or carbon arc gouging to cut and remove the stern fin structure of the corresponding area on the original hull as a whole, forming an installation opening that matches the sub-assembly module.

[0011] S4: Transport the entire sub-assembly module to the bottom of the predetermined installation position, and use a lifting device to hoist the sub-assembly module to the installation position; transport the prefabricated sub-assembly module to below the stern of the ship, aligning it with the installation opening formed in step S3. Then, using a lifting device installed on the ship's bottom plate (or a sturdy structure), hoist the sub-assembly module vertically upward from the bottom to the installation opening.

[0012] S5. Adjust, align, and weld the sub-assembly modules to the retained structure of the ship. Finely adjust and align the sub-assembly modules, which have been raised to the installation position, with the retained stern fin structure on the hull to ensure that key dimensions such as centerline, spacing, and levelness meet design requirements. After verification, weld the peripheral interfaces of the sub-assembly modules to the retained hull structure to complete the structural integration.

[0013] Furthermore, in step S2, the fabrication of the small assembly module specifically includes: S21: Fabricate and weld the bottom foundation frame and the upper frame according to the drawings of the sub-assembly module; according to the manufacturing drawings of the sub-assembly module, cut materials and weld them to form the bottom foundation frame and the upper frame. The bottom foundation frame and the upper frame are generally divided by the position of the horizontal reinforcing flat iron of the side push device (that is, the center position of the cylinder height).

[0014] S22: The bottom base frame has U-shaped slots at the points where it interferes with the reinforcing rings axially aligned with the cylindrical structure. This allows the bottom base frame to hold the horizontal reinforcing flat iron in place, providing a positioning reference for the cylindrical structure in the height direction. U-shaped slots are pre-formed on the bottom base frame at locations where the reinforcing rings axially aligned with the cylindrical structure would interfere. Thus, when the cylindrical structure is placed on the base frame, its reinforcing rings can be embedded in these U-shaped slots, providing a precise and stable positioning reference for the cylindrical structure in the height direction (Z-axis), preventing it from sinking or shifting.

[0015] S23: The fabrication of the modular assembly requires ensuring the base plate is level on the jig, and drawing ground lines at the center of the front and rear widths and the center of the left and right cylinders. These ground lines are used to adjust the position of the cylinder structure on the bottom foundation frame. After the position is adjusted, welding reinforcement is performed. First, adjust the jig to ensure its base plate is level. Then, draw ground lines such as the center lines of the front and rear widths of the module and the center lines of the left and right cylinder structures on the jig platform. Hoist the fabricated bottom foundation frame onto the jig, adjust its position according to the ground lines, and fix it. Subsequently, hoist the cylinder structure onto the foundation frame, and use the U-shaped groove and ground lines to accurately position it in the X, Y, and Z directions. After confirming that it is correct, weld the cylinder structure to the foundation frame for reinforcement.

[0016] S24: The upper frame and the bottom foundation frame are welded together. The pre-fabricated upper frame is hoisted onto the positioned cylinder and foundation frame. After adjustment and alignment, the upper frame is welded together with the bottom foundation frame and cylinder structure to form a complete and closed sub-module.

[0017] Furthermore, in step S4, the lifting device includes lifting lugs and a hand-operated hoist mounted on the ship's bottom plate. The hand-operated hoist pulls the sub-assembly module to the installation position. The lifting device includes multiple lifting lugs welded or fixed to the ship's internal bottom plate or strong structure, and a hand-operated or electric hoist connecting the lifting lugs and the lifting points of the sub-assembly module. By simultaneously operating multiple hoists, the sub-assembly module can be smoothly and controllably lifted vertically from the bottom of the ship to the installation opening position.

[0018] Furthermore, in step S4, a forklift is first used to move the sub-assembly module directly below the predetermined installation position. Before lifting with a lifting device, a forklift or flatbed truck is first used to move or transport the sub-assembly module horizontally to directly below the predetermined installation position to facilitate subsequent vertical lifting operations.

[0019] Furthermore, in step S5, the adjustment includes: when the lifting device hoists the sub-assembly module to the installation position, preliminary positioning is performed first, then scaffolding is erected to trim the excess material at the top of the first, second, and third frames. After the excess material is trimmed, final positioning is performed. When the lifting device hoists the sub-assembly module to near the installation position, preliminary positioning and temporary fixing are performed first. Then, construction workers erect scaffolding and measure and trim the actual excess material at the top of the first, second, and third frames of the sub-assembly module where they connect with the hull to ensure that the connection gap is uniform and meets welding requirements. After the excess material is trimmed, the temporary fixing is released, and the lifting device is used for fine-tuning to complete the final precise positioning.

[0020] Furthermore, in step S5, the alignment includes: ensuring that the centerline of the base plate of the sub-assembly module is aligned with the centerline of the base plate of the retained ship structure, and ensuring that the spacing between the front and rear frames of the sub-assembly module meets the requirements of the drawings. The key to alignment is ensuring that the centerline of the base plate of the sub-assembly module is strictly aligned with the centerline of the base plate of the retained ship structure; simultaneously, it is necessary to verify and ensure that the spacing between the front and rear frames (such as the first and third frames) of the sub-assembly module is completely consistent with the spacing of the original structure at the corresponding position on the hull or the design requirements of the drawings.

[0021] To achieve the above objectives, another technical solution of the present invention is to design a side thruster assembly module, including a cylindrical structure of a stern side thruster and a partial stern fin structure welded integrally with the cylindrical structure. The partial stern fin structure includes at least a first, second, and third skeleton, and U-shaped slots are provided on the first, second, and third skeletons for engaging with reinforcing rings axially arranged in the cylindrical structure.

[0022] The advantages and beneficial effects of this invention are as follows: By shifting the process forward, most of the disassembly, positioning, and assembly work is transferred to the dock jig for completion, forming an integral module. The workload within the dock is significantly reduced, shortening the lifting time from approximately 4 days using traditional methods to just 1 day, effectively addressing the challenges of short dock periods. Modular construction simplifies dock procedures; the overall lifting and positioning steps are clear and quick, with initial positioning requiring only about 0.5 hours. The prefabrication environment on the jig is superior to the confined space within the dock, which helps ensure welding quality and structural accuracy. The jig allows for precise setting of ground lines and the use of U-shaped slots in the frame to hold the flat iron of the cylinder, pre-solving key positioning issues such as height and centering. The dock lifting process primarily involves vertical lifting, avoiding the risks of traditional inclined pulling and multiple adjustments, resulting in high operational safety. It avoids extensive disassembly for lifting and subsequent restoration of the original structure, reducing labor, time, and material consumption, thus lowering overall construction costs. Simultaneously, the modular assembly ensures construction quality and avoids the welding difficulties caused by the confined space of previous methods. Attached Figure Description

[0023] Figure 1 This is a flowchart of the construction method of the present invention; Figure 2 This is a flowchart of step S2 of the construction method of the present invention; Figure 3 This is a schematic diagram of the side-push group stand-up module structure.

[0024] In the diagram: 1. Cylindrical structure; 11. Reinforcing flat iron; 12. Reinforcing ring; 2. Bottom base frame; 21. First skeleton; 22. Second skeleton; 23. Third skeleton; 24. U-shaped groove; 3. Upper frame. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0026] Example 1: Construction Method This embodiment describes the modification of a vessel by adding a stern thruster. According to the drawings, the bow thruster was disassembled and added to the stern guide fins FR10-FR12 (i.e., the first, second, and third frames), with the center at a position 1700 mm from the baseline. This project was a dockside project with a short docking period.

[0027] according to Figure 1As shown, step S1: Design phase. Based on the ship's lines, structural drawings, and the selected thruster model and hull drawings, the design department creates a 3D model in the computer. After determining the optimal installation position of the thruster hull in the stern fin, a reasonable prefabrication module area is defined. This area must include the complete thruster hull and the surrounding hull structures that must be connected to form a stable load-bearing structure. In this example, the module includes the hull and the main areas governed by the first frame 21, second frame 22, and third frame 23 distributed along the ship's length. Detailed prefabrication module construction drawings are generated, including part drawings, assembly drawings, jig drawings, etc.

[0028] Step S2: Prefabrication stage.

[0029] First, set up and calibrate a horizontal jig on site to ensure that its working surface is level. Accurately mark the width center line and cylinder center line, etc., on the jig panel.

[0030] according to Figure 2 As shown, next, in step S21, materials are cut and welded according to the drawings to form the bottom base frame 2 (which integrates the lower part of the first, second, and third skeletons 23 and the connecting ribs) and the upper frame 3. The bottom base frame 2 and the upper frame 3 are generally divided by the position of the horizontal reinforcing flat iron 11 of the side pushing device (that is, the center position of the cylinder height), which means that the first skeleton 21 and the third skeleton 23 are divided into upper and lower parts.

[0031] In step S22, when assembling the bottom base frame 2, according to the cylinder drawing, a U-shaped groove 24 is cut on the corresponding panel of the base frame at the position where the reinforcing ring 12 set axially in the cylinder will pass.

[0032] In step S23, the bottom foundation frame 2 is hoisted onto the jig, its position is adjusted according to the ground line, and it is then spot-welded in place. Next, the side-push cylinder is hoisted in and placed on the foundation frame. At this point, the reinforcing ring 12 on the outer wall of the cylinder falls precisely into or rests within the pre-set U-shaped groove 24, providing a precise height reference for the cylinder while restricting its horizontal movement. The cylinder is adjusted so that its centerline aligns with the ground line on the jig. After completing precise positioning in the X, Y, and Z directions, the cylinder is then formally welded to the foundation frame.

[0033] Finally, in step S24, the prefabricated upper frame 3 is hoisted and fitted onto the cylinder and foundation frame. After alignment, it is welded to form a complete closed structure, i.e., the small assembly module. All welds undergo non-destructive testing (such as UT and RT).

[0034] Step S3: Hull Cutting. The vessel enters the dry dock or moors at a sturdy pier. At the designated installation area on the stern side, precisely mark lines on the hull plating and internal structure according to the dimensions of the assembled modules. Then, using equipment such as a plasma cutter, cut and remove the original stern fin structure along the marked lines, creating a neat installation opening. Care must be taken to protect any surrounding structures that do not need to be removed during the cutting process.

[0035] Step S4: Module Lifting and Elevation. Use a forklift to transport the prefabricated sub-assembly modules to directly below the stern of the hull, roughly aligning the modules with the installation openings above. Inside the vessel, weld and install multiple load-bearing lifting lugs onto the bottom plate or strong beams around the installation openings. Connect the upper hooks of several hand-operated hoists to the lifting lugs, and connect the lower hooks to the pre-set lifting holes on the sub-assembly modules via shackles and wire ropes.

[0036] The commanders simultaneously and slowly pulled the chain of the hand-operated hoist to steadily and vertically lift the small assembly module upwards until it was fully inserted into the hull installation opening.

[0037] Step S5: Module positioning and welding.

[0038] Adjustment and Alignment: When the module is raised to a point where its base plate is close to the base plate of the retained hull structure, the process is paused. Construction workers adjust the module's position using the center line of the retained hull structure's base plate as a reference, aligning it with the center line. Simultaneously, the spacing between the ends of the first and third frames on the module and their corresponding frames on the hull is measured, and fine-tuned using a hoist to ensure the distance conforms to the drawings. This is preliminary positioning; temporary fixation by spot welding can then be performed.

[0039] Subsequently, scaffolding was erected, and the construction workers conducted detailed measurements on the upper ends of the first, second, and third skeletons 23 on the module and the docking edges with the hull retaining structure. Based on the actual gap, trimming lines were drawn, and excess material (residual material) was trimmed off using gas cutting tools to ensure a uniform docking bevel.

[0040] After trimming the excess material, remove the temporary fixing points and use a hand chain hoist again to perform a fine final positioning of the module, ensuring that all mating gaps and misalignments are within the allowable range specified in the specifications.

[0041] Welding and Fixing: After the positioning inspection is passed, qualified welders, following the welding procedure specifications, perform full penetration welding on all butt joints of the sub-assembly module's frame, outer plates, and other components to the remaining hull structure from the inside. Post-weld inspection and tightness testing are then conducted after welding.

[0042] With this, the main structure of the newly added stern thruster has been installed, and the subsequent installation of mechanical and electrical equipment such as the thruster blades, motors, and control systems can proceed.

[0043] according to Figure 3As shown, this embodiment provides a prefabricated side thruster assembly module using the above method. This module is a steel structure unit. Its core is the steel cylindrical structure 11 of the stern side thruster. Horizontal reinforcing flat irons 11 are welded to the outer wall of the cylindrical structure 11. The stern fin structure, welded integrally with the cylindrical structure, includes a first frame, a second frame, and a third frame arranged along the ship's length. These frames, along with their connecting plates and ribs, together form a stable base and peripheral support structure. Specifically, multiple U-shaped slots 24 are precisely cut into the bottom foundation frame 2, which constitutes the main load-bearing structure at the bottom of the module. During prefabrication, the axially arranged reinforcing rings 12 of the cylindrical structure are precisely embedded or rest against these U-shaped slots 24, thereby achieving rapid and precise positioning and rigid support of the cylindrical structure within the module. The entire module has completed all internal welding, inspection, and necessary painting before leaving the factory, and is delivered as a single component for on-site installation.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for constructing a new stern thruster device for a ship, characterized in that, Includes the following steps: S1: Design a small assembly module based on the ship construction drawings, the dimensions of the side thruster cylinder structure, and the installation position of the side thruster. S2: The cylindrical structure of the stern thruster and the stern fin structure containing the first, second and third skeletons are pre-assembled into a single modular assembly. S3: At the predetermined installation position at the stern of the ship, cut and remove the corresponding stern fin structure of the original ship along the outer contour line of the group assembly module; S4: Transport the entire sub-assembly module to the bottom of the predetermined installation position, and use a lifting device to lift the sub-assembly module to the installation position; S5. Adjust, align, and weld the assembled modules to the ship's remaining structure.

2. The construction method for a newly added stern thruster device of a ship according to claim 1, characterized in that, In step S2, the fabrication of the small assembly module specifically includes: S21: Fabricate and weld the bottom foundation frame and the upper frame according to the group assembly module drawings; S22: The bottom base frame has a U-shaped groove at the interference point of the reinforcing ring that is axially arranged with the cylindrical structure, so that the bottom base frame can hold the horizontal reinforcing flat iron and provide a positioning reference in the height direction for the cylindrical structure. S23: The fabrication of the small assembly module requires ensuring the base plate is level on the jig, and drawing ground lines at the center of the front and rear widths and the center of the left and right cylinders to adjust the position of the cylinder structure on the bottom foundation frame. After the position is adjusted, welding reinforcement is carried out. S24: The upper frame and the bottom base frame are merged and welded together.

3. The construction method for a newly added stern thruster device of a ship according to claim 1, characterized in that, In step S4, the lifting device includes a lifting lug and a hand-operated hoist installed on the bottom plate of the ship, and the hand-operated hoist is used to pull the small assembly module to the installation position.

4. The construction method for a newly added stern thruster device of a ship according to claim 1, characterized in that, In step S4, a forklift is first used to move the small assembly module directly below the predetermined installation position.

5. A construction method for a newly added stern thruster device on a ship according to claim 1, characterized in that, In step S5, the adjustment includes: when the lifting device lifts the small assembly module to the installation position, preliminary positioning is performed first, and then the upper margin of the first, second and third frames is trimmed by scaffolding. After the margin trimming is completed, final positioning is performed.

6. A construction method for a newly added stern thruster device on a ship according to claim 1, characterized in that, In step S5, the alignment includes: ensuring that the bottom plate of the sub-assembly module is aligned with the center line of the bottom plate of the ship's retained structure, and ensuring that the opening distance between the front and rear frames of the sub-assembly module meets the requirements of the drawings.

7. A side-pushing group assembly module prefabricated according to any one of claims 1 to 6, characterized in that, The device includes a cylindrical structure for a stern thrust device and a partial stern fin structure welded integrally with the cylindrical structure. The partial stern fin structure includes at least a first, second, and third skeleton, and the first, second, and third skeletons are provided with U-shaped slots for engaging with reinforcing rings axially arranged in the cylindrical structure.

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