Construction method of long shaft system of thin plate ship

Abstract

The application discloses a kind of sheet warship long shaft system construction method, belong to warship shaft system construction technical field, solve the technical problem of long construction period of existing hull shaft system.The method can start shaft system construction after the main hull shaft system area is closed and formed, while shaft system construction is carried out, according to the process requirement, the subsequent closing of main hull, superstructure loading, main hull cabin test sealing, turbine professional base pad welding, engine room painting work is carried out, and shaft system construction is ended after the first layer superstructure loading is completed.In the case where the quality of shaft system is guaranteed, the shipbuilding period of warship berth can be greatly shortened, which creates good conditions for early construction of subsequent processes.

Description

Technical Field

[0001] This invention relates to the field of ship shafting construction technology, and more specifically, to a method for constructing long shafting systems for thin-plate ships. Background Technology

[0002] Currently, most ship propulsion systems adopt a long shaft system layout. The installation of long shaft systems (especially ultra-long shaft systems) runs through the entire construction phase of a ship, and the speed of its construction directly affects the length of the ship construction cycle, playing an extremely important role in whether the shipyard can complete the ship on schedule.

[0003] like Figure 1 As shown, existing ship shafting construction can only begin after the main hull and superstructure are welded, heat-worked and corrected, the main hull is tested for tightness, and the entire ship is simulated and ballasted. This results in a long shipbuilding cycle, low efficiency, high shipyard production costs, and poor economic returns. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art. The purpose of the present invention is to provide a construction method for the long shaft system of thin-plate ships that can shorten the shipbuilding cycle.

[0005] To achieve the first objective mentioned above, this invention provides a method for constructing long shafting systems for thin-plate ships. After the shafting system area of ​​the main hull is assembled and formed, shafting construction can begin. Simultaneously with shafting construction, subsequent work such as main hull assembly, superstructure installation, main hull compartment tightness testing, engine room base gasket welding, and engine room painting is carried out according to the process requirements. Shafting construction ends after the first layer of superstructure is installed.

[0006] As a further improvement, the specific construction procedure is as follows: The main hull shafting area is assembled and formed → The slipway pier positions are adjusted according to the shafting construction stage, the piers are tightened and compacted, and the hull in the shafting area is measured and adjusted → The first string line measurement is performed to determine the shafting baseline → The ground survey line at the stern of the shafting is marked → The reference points at the bow and stern of the shafting are marked and confirmed, and height monitoring poles are erected on the ground at the bow and stern of the shafting → The main engine base panel and small base, gearbox base panel, intermediate bearing seat, and brake device seat are installed → While the base is being installed, the stern shaft bracket and stern tube are pre-assembled, and the surrounding structure and the embedded thickened outer plates are installed → Pre-welding measurement of the base is performed. Beveling inspection → Base welding, welding of the structure around the stern shaft bracket and stern tube, including welding of the embedded outer plate thickening plate → Base welding, welding and post-weld measurement and inspection → Welding of engine fixing shims → Engine room painting → Full ship ballast simulation, hull condition measurement and confirmation → Re-inspection of shafting bow and stern reference points, second string line measurement, shafting baseline adjustment → Re-inspection and adjustment of stern shaft bracket and stern tube installation measurement → Bracket arm and stern tube installation and beveling inspection → Bracket arm and stern tube welding, inspection → Post-weld stress relief and reinforcement removal of stern shaft bracket, flaw detection and tightness inspection → Post-weld data measurement and inspection → Delivery to marine engineering professionals for construction.

[0007] Furthermore, the conditions for shaft system construction include:

[0008] In the base section, the main hull of the shafting area is assembled and formed, and the main assembly and welding are completed;

[0009] In the stern shaft frame section, the hull is formed, and the main assembly, welding, and firework are completed; the main hull water-filled compartment tightness test is completed, and the main tightness test of the shafting arrangement area is completed; the first superstructure is installed; ballast is carried out according to the "Main Equipment Ballast Arrangement Diagram", and the main equipment is moved into the compartment or replaced with ballast of similar weight; before shafting construction, the hull condition data is measured, confirmed, and recorded.

[0010] Furthermore, during the initial shafting installation, once the conditions for shafting construction are met, the shafting installation and welding work will be carried out simultaneously with the main hull assembly, including the following tasks:

[0011] Adjust the hull shaft baseline based on the preliminary measurement data of the hull condition;

[0012] Construction of the base section, including the installation and positioning of the main unit base and small base, gearbox base, intermediate bearing base, and brake device base;

[0013] Construction of the stern shaft support section, including the installation and positioning of the stern shaft support and stern tube;

[0014] Welding is performed on the main engine base and small base, gearbox base, intermediate bearing base, and brake device base. Welding is also performed on the structure around the stern shaft frame and stern tube, including the welding of the embedded outer thickening plate.

[0015] Furthermore, during the second shafting installation, the main hull assembly, welding, heat treatment, and sealing were completed. Simultaneously with the hoisting of the first superstructure, the adjustment and welding of the shafting stern bracket were carried out, including the following tasks:

[0016] The entire ship was subjected to simulated ballast loading, hull condition measurement and shafting reference point verification, baseline and axis fine-tuning, secondary stringing to remeasure the stern shaft bracket and stern shaft tube installation data, verification of whether they meet the accuracy requirements and timely adjustments were made.

[0017] The stern shaft bracket arm is reinforced and positioned by welding with the surrounding hull structure and the embedded thickened outer plate, and then welding is carried out in the welding sequence.

[0018] Welding of the stern tube;

[0019] Inspection of stern tube and stern bracket welding;

[0020] After the welding of the first superstructure is completed, the shaft system data is checked to ensure it meets the accuracy requirements before being handed over to the marine engineering team for construction.

[0021] Furthermore, the welding sequence requirements are as follows:

[0022] Before formal welding, welders must perform reinforcement locating welding inside and outside the cabin;

[0023] The welding procedure is as follows: first, the hull structure connected to the stern shaft bracket arm and the embedded outer plate thickening plate are symmetrically welded; then, the weld seam on the reverse side of the stern shaft bracket arm and the embedded outer plate thickening plate is cleaned with carbon fiber and ground, and then welded.

[0024] During the welding inside the cabin, the structural butt joint is welded first, then the vertical fillet weld between the bracket arm and the structure is welded, and finally the flat fillet weld is welded. Before welding the stern shaft bracket arm, a cutting torch is used to preheat the welding area and a 100mm area on both sides, with a preheating temperature of 120-200℃.

[0025] During welding, one welder performs symmetrical welding on the stern shaft bracket arm;

[0026] When welding the embedded outer plate thickening plate to the stern shaft bracket arm at an angle, carbon dioxide gas shielded welding is used. Before welding, the welding part and a 100mm range on both sides are preheated with a cutting torch. The preheating temperature is 120-200℃.

[0027] Furthermore, the welding of the stern tube includes:

[0028] Welding of the stern tube end plates to the transverse bulkhead plates and solid rib reinforcing rings;

[0029] The stern tube is constructed by two welders at each end simultaneously.

[0030] The welding of the stern tube to the hull structure is mostly circumferential weld. To reduce welding deformation, intermittent welding must be used. Symmetrical reinforcement welding is performed first, followed by symmetrical welding after the entire strip is welded to the root.

[0031] Before welding the stern tube, the welding sequence of the stern tube can be adjusted based on the deviation direction of the overall post-weld data of the three stern tube frames on the same axis.

[0032] Furthermore, after the welding of the stern tube and stern frame is completed, the weld of the stern frame is subjected to heat stress relief. After the weld cools down, the support reinforcement is removed and the base plate is ground. The welding of the stern tube and stern frame is then submitted for inspection.

[0033] Furthermore, the E5015 welding rods used in the welding process must be dried at 300-350℃ for 1-2 hours before use and stored in a welding rod insulation cylinder. The insulation cylinder must be kept warm by electricity during the welding process, and the welding rods should be taken out as needed.

[0034] Furthermore, the monitoring data of the entire shafting construction process was compiled into a booklet, including the phased changes in the hull condition, the comparison of pre- and post-weld measurement data of the shafting base and stern shaft frame, and the hull completion data, for analysis and summarization, and as a guide for subsequent ships.

[0035] Beneficial effects

[0036] Compared with the prior art, the advantages of this invention are as follows:

[0037] This invention moves the shafting construction process forward, allowing it to be carried out in parallel with other processes. Early construction of the main shafting project on the slipway provides superior conditions and a foundation for subsequent processes. While ensuring quality, it significantly shortens the slipway construction cycle of ships, particularly by about one month. This frees up valuable slipway space for the company, saving resources and costs in various aspects for its core shipbuilding business, and the resulting benefits will become increasingly apparent. Attached Figure Description

[0038] Figure 1 This is a standard construction procedure diagram for ship shafting.

[0039] Figure 2 This is a construction procedure diagram for the ship shafting system of the present invention;

[0040] Figure 3 This is a diagram showing the standard production process on a shipyard.

[0041] Figure 4 This is a diagram showing the production process arrangement of the shipyard according to the present invention;

[0042] Figure 5 A schematic diagram of the stern shaft bracket arm and the embedded thickened outer plate;

[0043] Figure 6 A cross-sectional view of the stern shaft bracket arm and the embedded thickened outer plate;

[0044] Figure 7 This is a diagram showing the welding sequence of the stern tube to the hull structure. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0046] See Figures 1 to 7 A method for constructing long shafting systems for thin-plate ships is described. After the shafting system area of ​​the main hull is assembled and formed, shafting construction can begin. Simultaneously, the subsequent assembly of the main hull, the installation of the superstructure, the testing of the main hull compartments, the welding of the engine room base gaskets, and the painting of the engine room are carried out according to the process requirements. The shafting construction is completed after the first layer of superstructure is installed.

[0047] The specific construction procedure is as follows: The main hull shafting area is assembled and formed → The slipway pier positions are adjusted according to the shafting construction stage, the pier timbers are tightened and compacted, and the hull in the shafting area is measured and adjusted → The first string line measurement is performed to determine the shafting baseline → The ground survey line at the stern of the shafting is marked → The reference points at the bow and stern of the shafting are marked and confirmed, and height monitoring poles are erected on the ground at the bow and stern of the shafting → The main engine base panel and small base, gearbox base panel, intermediate bearing seat, and brake device seat are installed → While the base is being installed, the stern shaft frame and stern tube are pre-assembled, and the surrounding structure and embedded thickened outer plates are installed → Pre-welding measurement and beveling inspection of the base → Base welding, and welding of the stern shaft frame and stern tube. The structural welding process begins with the welding of the embedded outer thickening plates (note that welds directly connecting to the stern shaft bracket and stern tube are not welded initially) → welding of the base section, followed by welding and post-weld measurement and inspection → installation and welding of engine mounting shims → painting of the engine room → simulated ballasting of the entire ship, confirmation of hull condition measurement → re-checking of the shafting's fore and stern reference points, second string line measurement, and adjustment of the shafting baseline → installation, measurement, re-checking, and adjustment of the stern shaft bracket and stern tube → installation and beveling inspection of the bracket arm and stern tube → welding of the bracket arm and stern tube, and inspection → post-weld stress relief and reinforcement removal of the stern shaft bracket, flaw detection, and tightness testing → post-weld data measurement and inspection → delivery to the marine engineering team for construction.

[0048] The optimized construction plan for the shaft system is as follows:

[0049] (a) The conditions for shaft system construction include the following two parts:

[0050] 1. In the base section, including the pre-assembly and welding stage of the stern shaft bracket and stern tube:

[0051] The main hull in the shafting area has been assembled and formed, and the main assembly and welding have been completed.

[0052] 2. In the stern shaft bracket section, including the final adjustment and welding stage of the stern shaft bracket and stern tube:

[0053] (1) The hull is formed, mainly through assembly, welding, and firework.

[0054] (2) The water tightness test of the main hull water-filled compartments is completed, and the main tightness test of the shafting arrangement area is completed (except for the seabed valve box).

[0055] (3) The first floor of the superstructure has been completed.

[0056] (4) Ballasting shall be carried out in accordance with the "Main Equipment Ballast Layout Plan" (the "Main Equipment Ballast Layout Plan" is formed during the design of the ship), and the main equipment shall be moved into the cabin or replaced with ballast of similar weight.

[0057] (5) Before shafting construction, measure and confirm the hull condition data. The hull condition includes the centering, port and starboard level, keel deflection, and bow and stern tilt. Set up benchmark monitoring points, monitor the hull condition at fixed times every day and keep records, as shown in Table 1 below.

[0058]

[0059] Table 1

[0060] (II) The shaft system construction process optimization plan includes the following three parts:

[0061] 1. At the start of the first shafting installation (i.e., the first shafting measurement), after the shafting construction conditions are met, the shafting installation and welding work shall be carried out simultaneously with the main hull assembly, including the following work:

[0062] (1) Adjust the hull shaft baseline based on the previous measurement data of the hull condition. The impact of subsequent hull assembly and welding, superstructure hoisting, and full ship ballast on the bow and stern warping and keel deflection of the main hull (hull condition) should be fully considered. The bow and stern ends and the shaft reference points at the bow and stern can be appropriately adjusted in the vertical direction to apply the anti-deformation amount, and the first shaft alignment inspection should be carried out.

[0063] (2) Construction of the base, including the installation and positioning of the main unit base and small base, gearbox base, intermediate bearing base and brake device base.

[0064] According to the requirements of the ship's shafting system and construction process, cut the upper margin of the main engine mount web, gearbox mount web, main engine base, intermediate bearing seat, and brake device mount web. Install and position the main engine mount panel and base, gearbox mount panel, intermediate bearing seat, and brake device seat. The installation height deviation is ±2mm, the half-width deviation is ±2mm, and the distance deviation from the stern reference point must be in the same direction. Ensure proper support and reinforcement.

[0065] Beveling type and welding requirements: The outer sides of the upper opening of the main body web plate, the upper opening of the gearbox web plate, and the lower opening of the small base should have a single-sided beveling without leaving a root (it should be noted that the internal space of the base is relatively large, which facilitates subsequent carbon gouging and root cleaning). The reverse side should be carbon gouged for root cleaning, and both sides should be fully penetrated.

[0066] (3) Construction of the stern shaft frame (including the pre-assembly and welding stage of the stern shaft frame and stern shaft tube), including the installation and positioning of the stern shaft frame and stern shaft tube.

[0067] According to the requirements of the ship's shafting system and construction process, the stern shaft bracket arms and stern shaft tubes are drilled according to the axis wire and hole pattern on the outer plate of the hull bottom, and the positioning stern shaft brackets are installed. The three stern shaft brackets on the same axis must be constructed within the same time period to reduce the impact of temperature differences on hull deformation and shafting accuracy. When positioning and installing the inner hole of the stern shaft bracket hub, coaxial and unidirectional deviation is required. Due to the large amount of construction work involved in the ten stern shaft brackets and their structures at the bottom of the stern, as well as the embedded thickened outer plate, a 1-1.5mm anti-deformation shrinkage allowance is applied outward along the outer axis. The hull structure around the stern shaft bracket arms and the embedded thickened outer plate are reinforced with proper support. Based on the overall deviation direction of the three stern shaft brackets on the same axis, the stern tube is positioned and installed. If the positioning is adjusted by adjusting the screw, the deviation direction of the installation is required to be consistent with that of the stern shaft bracket. The front end face of the stern tube does not release the counter-deformation, and the rear end face is placed downward with an appropriate amount of counter-deformation. The stern tube reinforcing ring plate at the shaft outlet of the hull is then installed.

[0068] Beveling and Welding Requirements: The web, face plates, embedded outer thickened plates, and stern tube reinforcing rings of the structural components surrounding the stern shaft bracket should all have single-sided beveling without root clearance. For butt welds of the embedded outer thickened plates, a ceramic backing beveling can be used, with the reverse side cleaned by carbon gouging, ensuring complete penetration on both sides. Where the space below the stern tube fillet weld is limited, a ceramic backing beveling can be cut outwards and secured with clips, followed by welding with the ceramic backing attached, resulting in a complete penetration weld on both sides. It is important to note that the embedded outer thickened plates of the stern shaft bracket should have a beveling on the inner side of the compartment to facilitate subsequent carbon gouging and root clearance work on the outer side of the compartment.

[0069] (4) Weld the main engine base and small base, gearbox base, intermediate bearing base, and brake device base; weld the structure around the stern shaft frame and stern tube, including the welding of the embedded outer thickening plate. Note that welds directly connecting to the stern shaft frame and stern tube will not be welded at this stage. Welding inspection reports for the main engine base and small base, gearbox base, intermediate bearing base, and brake device base are submitted; the turbine engineering team measures the base data; and the turbine runner team installs and welds the fixing shims for each base.

[0070] 2. During the second shafting guying construction (i.e., the second guying measurement), the main hull assembly, welding, heat treatment, and tightness testing were completed. Simultaneously with the hoisting of the first superstructure, the adjustment and welding work of the shafting stern shaft bracket was carried out, including the following tasks:

[0071] (1) Full ship ballast simulation, hull condition measurement and shaft system datum point re-check, baseline and axis fine adjustment, that is, adjustment within the tolerance standard range of hull keel deflection tolerance ±8mm, shaft system centerline vertical deviation ±3mm, and shaft hub inner hole single-sided boring allowance, to determine the shaft system datum points. Secondary string line re-measurement of stern shaft bracket and stern shaft tube installation data (confirming unidirectional alignment), re-check whether it meets the accuracy requirements and adjust in time.

[0072] (2) The stern shaft bracket arm is reinforced and tack-welded to the surrounding hull structure and the embedded outer plate thickening plate, and then welded according to the welding sequence. The welding sequence requirements are as follows:

[0073] ① Before formal welding, welders must perform reinforcement positioning welding inside and outside the cabin.

[0074] ②The welding procedure is as follows: first, the hull structure connected to the stern shaft bracket arm and the embedded outer plate thickening plate are symmetrically welded; then, the weld seam on the reverse side of the stern shaft bracket arm and the embedded outer plate thickening plate is cleaned and ground with carbon planing before welding.

[0075] ③ When welding inside the cabin, first weld the structural butt joint, then weld the vertical fillet weld between the bracket arm and the structure, and finally weld the horizontal fillet weld. Before welding the stern shaft bracket arm, use a cutting torch to preheat the welding area and a 100mm area on both sides, with a preheating temperature of 120-200℃.

[0076] ④ During welding, one welder shall perform welding symmetrically on the stern shaft bracket arm.

[0077] ⑤ When welding the embedded outer plate thickening plate to the stern shaft bracket arm at an upward angle, carbon dioxide gas shielded welding is used. Before welding, the welding part and the area within 100mm on both sides are preheated with a cutting torch. The preheating temperature is 120~200℃.

[0078] By adjusting the welding parameters according to the welding process requirements, welding can be carried out continuously without requiring each weld to cool before applying the next. It is also unnecessary to constantly monitor the stern shaft bracket data with a steel wire during the welding process, which would lead to inefficient construction. A welding diagram is shown below. Figure 5 , Figure 6 As shown.

[0079] (3) Welding of the stern tube, including:

[0080] ① Including the welding of the front and rear end seats of the stern tube to the transverse bulkhead and the solid rib reinforcing ring.

[0081] ② The stern tube is constructed by two welders at the beginning and end.

[0082] ③ The welding of the stern tube to the hull structure is mostly circumferential weld. To reduce welding deformation, intermittent welding must be used. Symmetrical reinforcement welding is performed first, followed by symmetrical welding after the entire strip has been welded to the root pass. Figure 7 As shown.

[0083] ④ Before welding the stern tube, the welding sequence of the stern tube can be adjusted according to the deviation direction of the overall post-weld data of the three stern tube frames on the same axis.

[0084] (4) Inspection of stern tube and stern bracket welding:

[0085] After the welding of the stern shaft bracket and stern tube is completed, the weld of the stern shaft bracket is subjected to heat treatment to relieve stress. After the weld cools, the support reinforcement is removed, and the mounting feet are ground. The welding of the stern tube and stern shaft bracket is then submitted for inspection.

[0086] After the angle weld of the stern shaft bracket arm has completely cooled, the weld and a 100mm area on both sides are ground smooth and the paint is removed. 24 hours after welding, the surface quality of the fillet weld is inspected using magnetic particle testing. After the welds of the stern shaft bracket and stern tube pass the flaw detection, a weld tightness test is performed. Finally, the post-weld data of the stern shaft bracket and stern tube are measured and reported for inspection.

[0087] (5) After the welding of the first superstructure is completed, the shafting data is checked to ensure it meets the accuracy requirements before being handed over to the marine engineering team for construction. The shafting data can be adjusted within the tolerance range of ±8mm for hull keel deflection, ±3mm for vertical deviation of shafting centerline, and 5mm boring allowance on one side of shaft hub inner hole, and finally the head and tail reference points of the shafting are determined.

[0088] (6) The monitoring data of the entire shafting construction process is compiled into a book, including the phased changes in the hull status (the reference points at the bow and stern of the shafting), the comparison of measurement data before and after welding of the shafting base and the stern shaft frame, and the hull completion data, for analysis and summary, and as a guide for subsequent ships.

[0089] 3. Quality control requirements for hull shafting assembly

[0090] (1) Construction personnel must be familiar with the drawings and construction process, and understand the construction content and technical requirements.

[0091] (2) Construction can only proceed after the sketches, wire drawing boards and hole templates provided by the design department have been confirmed by the process engineer.

[0092] (3) Draw the axis system ground line according to the line drawing sketch, install the line drawing board (frame) and find the bow and stern reference points of the axis, and report the bow and stern reference points for inspection.

[0093] (4) The accuracy of the data for the main engine and stern shaft axis, and the bow and stern reference points of the stern shaft axis, and the distances from CL and BL. The accuracy of the axis reference points is controlled to be no more than 1mm.

[0094] (5) Ensure the accuracy of the installation height and half-width of the main unit base, small base, gear base, intermediate bearing base, brake device base, etc., relative to the axis.

[0095] (6) Control of the installation anti-deformation data of the inner and outer stern shaft brackets and stern shaft tubes.

[0096] (7) Quality control of hull shafting structure installation. In order to reduce welding deformation of structural components and ensure installation quality, the installation gap shall be controlled to be no more than 2mm.

[0097] (8) All structural components, such as webs and panels, must be beveled according to the welding process requirements and drawings.

[0098] (9) After the bracket is installed, three angle steels are used to reinforce the front and rear ends. The reinforcement must be supported at the hard section of the hull, and a pad must be added at the connection between the reinforcement and the hull. It must not be directly spot welded to the outer plate of the hull.

[0099] (10) After the shaft system is installed, beveling, installation measurement and inspection shall be carried out.

[0100] (11) After the assembly is inspected and approved, the data is provided to the welding process, the process is explained on site, and the welding process is monitored and the welding deformation is controlled.

[0101] (III) The requirements for welding include the following four parts:

[0102] 1. Main welding items

[0103] Serial Number Main welding projects Material quantity Remark 1 Stern shaft support ZG230-450H 10 There are 6 outer axes and 4 inner axes. 2 Stern tube Q345-B 4 Two outer shafts, two inner shafts 3 Small base DH36 24 There are 8 outer axes and 16 inner axes. 4 Main unit and gearbox base panel DH36 10 items Six outer shafts and four inner shafts 5 intermediate bearing housing DH36 6 There are 4 outer shafts and 2 inner shafts. 6 Brake mount DH36 4 Two outer shafts and two inner shafts

[0104] 2. Welding equipment

[0105] (1) 6 to 8 CO2 gas shielded welding machines to ensure symmetrical welding of the shaft system. The welding machines should be adjusted before formal welding.

[0106] (2) Wire brush and slag hammer.

[0107] 3. Welding materials

[0108] (1) E5015 welding rod Φ3.2mm. In order to strengthen the control of welding deformation, the principle of welding material selection must be strictly implemented and the use of Φ4.0mm welding rod is prohibited.

[0109] (2) Before use, E5015 welding rods must be dried at 300-350℃ for 1-2 hours and stored in a welding rod insulation cylinder. The insulation cylinder must be powered on to keep warm during the welding process. Welding rods should be taken out as needed.

[0110] (3) CO2 gas shielded welding uses Supercored-71 flux-cored wire, Φ1.2mm.

[0111] 4. Welding process parameters

[0112] (1) Manual arc welding with welding rods

[0113] Electrode diameter (mm) Flat welding current (A) Vertical welding current (A) Horizontal welding current (A) Overhead welding current (A) Φ3.2 110～150 100～130 100～140 90～130

[0114] (2) CO2 gas shielded welding

[0115]

[0116] Innovative breakthroughs have been made in process upgrading and optimization, parallel processing, process connection, and acceptance procedure optimization. The original shafting construction could only begin after the main hull and superstructure were welded, heat-worked, and tested for tightness in the main hull, and after the entire ship was simulated and ballasted. The new shafting construction process allows construction to begin immediately after the main hull shafting area is assembled and formed. Simultaneously, subsequent main hull assembly, superstructure installation, main hull compartment tightness testing, and welding of engine room base gaskets and engine room painting are carried out, all concluding after the first superstructure is installed. This shortens the slipway construction cycle by approximately one month.

[0117] By developing a hull condition monitoring table and tracking and analyzing it daily, and by taking control measures such as the tightness of the piers at the slipway, the accuracy of the main hull assembly, the amount of deformation caused by the release of the assembly counter-deformation, and the temporary application of ballast irons to the bow and stern ends of the main hull, and by adjusting and controlling within the range of hull construction tolerances and shafting component allowances, we strive to keep all variables affecting the shafting within the accuracy range.

[0118] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A construction method for a long shaft system of a thin-plate ship, characterized in that, After the main hull shafting area is assembled and formed, shafting construction can begin. While the shafting construction is underway, the subsequent assembly of the main hull, the installation of the superstructure, the testing of the main hull compartments, the welding of the engine professional base gaskets, and the painting of the engine room are carried out in accordance with the process requirements. The shafting construction is completed after the first superstructure is installed. At the start of the first shafting installation, once the conditions for shafting construction are met, the shafting installation and welding work will be carried out simultaneously with the main hull assembly. During the second shafting installation, the main hull assembly, welding, heat treatment, and sealing were completed. Simultaneously with the hoisting of the first superstructure, the adjustment and welding of the shafting stern frame were carried out.

2. The construction method for a long shaft system of a thin-plate ship according to claim 1, characterized in that, At the start of the first shafting installation, once the conditions for shafting construction are met, the shafting installation and welding work will be carried out simultaneously with the main hull assembly, including the following tasks: Adjust the hull shaft baseline based on the preliminary measurement data of the hull condition; Construction of the base section, including the installation and positioning of the main unit base and small base, gearbox base, intermediate bearing base, and brake device base; Construction of the stern shaft support section, including the installation and positioning of the stern shaft support and stern tube; Welding is performed on the main engine base and small base, gearbox base, intermediate bearing base, and brake device base. Welding is also performed on the structure around the stern shaft frame and stern tube, including the welding of the embedded outer thickening plate.

3. The construction method for a long shaft system of a thin-plate ship according to claim 1, characterized in that, During the second shafting installation, the main hull assembly, welding, heat treatment, and sealing were completed. Simultaneously with the hoisting of the first superstructure, adjustment and welding work was carried out on the stern shaft support section, including the following tasks: The entire ship was subjected to simulated ballast loading, hull condition measurement and shafting reference point verification, baseline and axis fine-tuning, secondary stringing to remeasure the stern shaft bracket and stern shaft tube installation data, verification of whether they meet the accuracy requirements and timely adjustments were made. The stern shaft bracket arm is reinforced and positioned by welding with the surrounding hull structure and the embedded thickened outer plate, and then welding is carried out in the welding sequence. Welding of the stern tube; Inspection of stern tube and stern bracket welding; After the welding of the first superstructure is completed, the shaft system data is checked to ensure it meets the accuracy requirements before being handed over to the marine engineering team for construction.

4. The construction method for a long shaft system of a thin-plate ship according to claim 3, characterized in that, Welding sequence requirements: Before formal welding, welders must perform reinforcement locating welding inside and outside the cabin; The welding procedure is as follows: first, the hull structure connected to the stern shaft bracket arm and the embedded outer plate thickening plate are symmetrically welded; then, the weld seam on the reverse side of the stern shaft bracket arm and the embedded outer plate thickening plate is cleaned with carbon fiber and ground, and then welded. During the welding inside the cabin, the structural butt joint is welded first, then the vertical fillet weld between the bracket arm and the structure is welded, and finally the flat fillet weld is welded. Before welding the stern shaft bracket arm, a cutting torch is used to preheat the welding area and a 100mm area on both sides, with a preheating temperature of 120-200℃. During welding, one welder performs symmetrical welding on the stern shaft bracket arm; When welding the embedded outer plate thickening plate to the stern shaft bracket arm at an angle, carbon dioxide gas shielded welding is used. Before welding, the welding part and a 100mm range on both sides are preheated with a cutting torch. The preheating temperature is 120-200℃.

5. The construction method for a long shafting system of a thin-plate ship according to claim 3, characterized in that, Welding of the stern tube includes: Welding of the stern tube end plates to the transverse bulkhead plates and solid rib reinforcing rings; The stern tube is constructed by two welders at each end simultaneously. The welding of the stern tube to the hull structure is mostly circumferential weld. To reduce welding deformation, intermittent welding must be used. Symmetrical reinforcement welding is performed first, followed by symmetrical welding after the entire strip is welded to the root. Before welding the stern tube, the welding sequence of the stern tube can be adjusted based on the deviation direction of the overall post-weld data of the three stern tube frames on the same axis.

6. The construction method for a long shaft system of a thin-plate ship according to claim 3, characterized in that, The welding inspection steps for the stern tube and stern frame include: after the welding of the stern tube and stern frame is completed, the weld of the stern frame is subjected to heat treatment to relieve stress. After the weld cools down, the support reinforcement is removed and the base plate is ground. The welding of the stern tube and stern frame is then submitted for inspection.

7. The construction method for a long shaft system of a thin-plate ship according to claim 1, characterized in that, The E5015 welding rods used in the welding process must be dried at 300-350℃ for 1-2 hours before use and stored in a welding rod insulation container. The insulation container must be kept warm by electricity during the welding process, and the welding rods should be taken out as needed.

8. The construction method for a long shafting system of a thin-plate ship according to claim 3, characterized in that, After the transfer to the marine engineering team for construction, the following steps are also included: the monitoring data of the entire shafting construction process is compiled into a book, including the phased changes in the hull condition, the comparison of pre- and post-weld measurement data of the shafting base and stern shaft frame, and the hull completion data, for analysis and summary, and as a guide for subsequent ships.

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