Sectional pre-outfitting method for tail shaft

Abstract

The invention discloses a stern shaft section pre-outfitting method, which belongs to the technical field of ship construction, and comprises the following steps: S1, 101, pre-installing a section stern tube bracket, S2, 102, pre-installing a section rudder system component, and S3, carrying, folding and monitoring. The stern tube bracket and the rudder system component are preassembled on the sections, and high-precision measuring and monitoring means are adopted in the carrying and folding process, so that the influence of carrying process change and work type cross operation on the component positioning precision is greatly reduced, and compared with a traditional slipway mounting mode, the positioning precision is remarkably improved, and the mounting period is greatly shortened.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a method for pre-outfitting stern shaft sections. Background Technology

[0002] In shipbuilding, the pre-outfitting of the shaft and rudder system is crucial. Taking the 693 container ship built by CSSC Guangxi Company as an example, the old process used to install shaft and rudder system components such as stern tube brackets, rudder pin seats, and rudder bearing seats on the slipway. This method has many problems. Changes in the hull during the assembly process and the cross-operation of different trades seriously affect the positioning accuracy of these components, resulting in a significant extension of the installation cycle. For example, when building the first 693 container ship in 2023, the installation of the cast steel stern tube brackets was only started after the stern sections 102 and 101 were assembled and the stern island was formed in early November. During this period, the intermediate hull assembly, welding, grinding, precision testing, painting and mechanical and electrical workshop fitter work were intertwined, with many transition points. The quality department also needed to conduct precision measurements to monitor the overall settlement baseline changes of the hull, which made the total construction period of the shipyard shaft and rudder system installation on the slipway as long as 82 days. Compared with the cycle of other shipyards, this was longer and greatly affected the construction efficiency of the whole ship and increased the production cost.

[0003] Meanwhile, the installation of the shaft and rudder system revealed issues such as insufficient understanding of the drawings and processes. For example, the design of the tapered push-in of the rudder blade and rudder stock did not adequately consider the insufficient space within the rudder blade window, resulting in the lack of hydraulic nut tooling. Other equipment had to be temporarily borrowed, and the push-in amount was insufficient, requiring further technical drawings and fabrication of the hydraulic nuts to resolve the issue. The stern shaft lifting point was poorly designed, and the lifting base lacked strength. Strengthening measures were implemented after the problem was discovered, resulting in a waste of manpower and time. Furthermore, the factory's incoming inspection system was inadequate. Issues such as discrepancies in the main engine's high-elasticity coupling dimensions were not detected in time when the equipment entered the cabin, leading to the main engine's high-elasticity coupling being returned to the factory for repair, further extending the construction period. These problems urgently require solutions through innovative pre-outfitting methods. Summary of the Invention

[0004] The main objective of this invention is to provide a pre-outfitting method for stern shaft sections, which solves the problems of poor positioning accuracy and long installation cycle in the existing shipyard shaft and rudder system component installation methods. By optimizing the pre-outfitting process, the accuracy of section fabrication and shipyard mounting is improved, the shipyard cycle is shortened, thereby improving the overall shipbuilding efficiency and reducing production costs.

[0005] To achieve the above objectives, the present invention proposes a stern shaft segment pre-outfitting method, comprising the following steps:

[0006] S1 and 101 segment stern tube support pre-installation: Invert the 101 segment stern tube support on the jig and mark each rib position. Then, the precision surveyor uses professional measuring tools and techniques to mark the axis 2300mm away from the baseline. Two reference points are vertically swept out by the plumb line and ground pattern marks are made. Then the cast steel part is hoisted in.

[0007] The S2 and 102 section rudder system components are pre-assembled. The 102 section is installed in reverse on the jig, with the upper deck surface as the bottom surface of the jig and the rudder arm facing upward. The precision surveyor first marks the rudder line at the 0# rib position, and then sweeps two reference points vertically up and down to make the midship line mark. Then, the midship line is used to position each part.

[0008] S3. Before the 101 section is hoisted, the midship line of the hull and the midship line of the gearbox main engine base are re-measured to ensure their accuracy. The high piers are hoisted to the bottom of the ship in sequence to prepare for the installation of the 101 section, ensuring that the midship line of the stern tube support is precisely aligned with the midship line of the main engine base.

[0009] Optionally, in step S1, marks are made on each rib position, from top to bottom as 5#, 6#, 7#, 8#, and 9#.

[0010] Optionally, the 9# rib of the closure opening is used as the ground of the jig, with the stern closure opening facing upwards. A positioning plate is welded at the 9# rib, and the stern tube support cast steel parts are precisely hoisted into position one by one, strictly controlling the overall dimensions according to the design requirements.

[0011] Optionally, in step 2, two adjustable cable holders are erected above the rudder arm and inside the rudder compartment. The rudder line is pulled out using steel wire, and then a total station is used for measurement and correction to ensure that the rudder line is vertically bisected and coincides with the segmented midline. Then, the rudder pin seat, lower rudder bearing, and upper rudder bearing are positioned in sequence according to the theoretical dimensions of the drawings.

[0012] Optionally, in step 2, after the welding of the 102 segment rudder pin seat is completed, the upper and lower rudder bearings are positioned but not welded yet, and fine-tuned according to the actual situation when they are assembled.

[0013] Optionally, in step 3, a total station is set up inside the engine room by means of precision measurement, so that it sweeps across the midline point of the main engine gearbox base and extends to the stern tube support to monitor the mounting process in real time.

[0014] Optionally, in step 3, after the segmented butt joints are aligned, the dressing table is spot-welded securely.

[0015] Optionally, the bottom of the ship below the section is supported by high blocks and welded together. Finally, the measurement data is collected and analyzed, and the gantry crane hook is released to complete the hoisting.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. By pre-installing the stern tube support and rudder system components on the sections and using high-precision measurement and monitoring methods during the assembly process, the impact of changes in the assembly process and cross-operations of different trades on the positioning accuracy of the components is greatly reduced. Compared with the traditional slipway installation method, the positioning accuracy is significantly improved.

[0018] 2. Significant progress has been made in advancing processes and improving techniques. Taking the 693 container ship as an example, the installation cycle of the shaft and rudder system for ship #2 was shortened by 46.35% compared to ship #1, and for ship #3 it was shortened by another 27.28% compared to ship #2. The overall installation cycle of the shaft and rudder system on the slipway was shortened by ≥40%. This not only accelerated the turnaround speed of the slipway but also laid a solid foundation for shortening the overall ship construction cycle and improved the shipyard's production efficiency.

[0019] 3. The shortened slipway cycle means less time spent on manpower, equipment, and other resources, thereby reducing production costs. Calculations show that, compared to ship #1, the shortened cycle for ship #3 will save approximately 51,500 yuan in costs for the pre-outfitting of the shaft and rudder sections. If this is extended to multiple ships, the economic benefits will be substantial. Simultaneously, the improved process enhances construction quality and reduces additional costs associated with rework and repairs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the steps of the present invention;

[0022] Figure 2 Construction drawings for the pre-installation of the 101-section stern tube support;

[0023] Figure 3 Construction drawings for the pre-assembly of the 102-section rudder system components;

[0024] Figure 4 For precision control;

[0025] Figure 5 A comparison chart of the installation times for ships #1, #2, and #3.

[0026] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0029] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0030] This invention proposes a stern shaft segment pre-outfitting method 100.

[0031] Please see Figures 2-5 In one embodiment of the present invention, the stern shaft segment pre-outfitting method 100 includes the following steps:

[0032] S1 and 101 segment stern tube support pre-installation: Invert the 101 segment stern tube support on the jig and mark each rib position. Then, the precision surveyor uses professional measuring tools and techniques to mark the axis 2300mm away from the baseline. Two reference points are vertically swept out by the plumb line and ground pattern marks are made. Then the cast steel part is hoisted in.

[0033] Mark each rib position with the following numbers from top to bottom: 5#, 6#, 7#, 8#, and 9#. Use rib position 9# at the closure opening as the base of the jig. With the stern closure opening facing upwards, position the positioning plate at the weld point of rib position 9#. Then, accurately hoist the stern tube support cast steel parts into position one by one, strictly controlling the overall dimensions according to the design requirements.

[0034] The S2 and 102 section rudder system components are pre-assembled. The 102 section is installed in reverse on the jig, with the upper deck surface as the bottom surface of the jig and the rudder arm facing upward. The precision surveyor first marks the rudder line at the 0# rib position, and then sweeps two reference points vertically up and down to make the midship line mark. Then, the midship line is used to position each part.

[0035] Two adjustable cable holders are erected above the rudder arm and inside the rudder compartment. The rudder cable is then stretched using steel wire, and a total station is used for measurement and calibration to ensure the rudder cable is perpendicularly bisected and coincides with the segmented midships line. The rudder pin seat, lower rudder bearing, and upper rudder bearing are then positioned sequentially according to the theoretical dimensions in the drawings. After the 102 segmented rudder pin seat is welded, the upper and lower rudder bearings are positioned but not welded yet; fine adjustments will be made based on the actual situation during assembly.

[0036] S3. Before the 101 section is hoisted, the midship line of the hull and the midship line of the gearbox main engine base are re-measured to ensure their accuracy. The high piers are hoisted to the bottom of the ship in sequence to prepare for the installation of the 101 section, ensuring that the midship line of the stern tube support is precisely aligned with the midship line of the main engine base.

[0037] In step S3, through precision measurement, the total station is set up in the engine room, sweeping across the midships line point of the main engine gearbox base and extending to the stern tube support to monitor the loading process in real time. After the segment joints are aligned, the comb blocks are spot welded firmly, and all the high piers on the bottom of the hull below the segment are supported and welded. Finally, the measurement data is sorted out and analyzed, and the gantry crane hook is released to complete the hoisting.

[0038] In practice:

[0039] Implementation steps for pre-installation of 101-section stern tube support

[0040] Before mounting section 101 onto the jig, the jig is inspected and calibrated to ensure its accuracy meets requirements. Section 101 is then hoisted onto the jig and fixed using a side-mounting method, ensuring that the 9# rib at the closure joint is tightly fitted to the jig ground. The precision surveyor uses a total station and other measuring tools to mark the axis line 2300mm from the baseline, according to the design drawings. During operation, a stable measurement environment must be maintained to avoid external factors interfering with the measurement results.

[0041] Two reference points were vertically marked using a plumb line, and clear, accurate ground markings were made using high-precision marking tools. Precise measurement and marking methods were also employed at each rib position to ensure the accuracy of the marking positions. When welding the positioning plate at rib #9, the quality and position of the welding were carefully controlled to ensure the positioning plate was secure and its position met design requirements. When hoisting the stern tube support cast steel component, appropriate lifting equipment was used to ensure that the cast steel component did not deform or get damaged during transport. The cast steel component was slowly hoisted into its positioning position and precisely adjusted according to the pre-marked position and size requirements. Real-time measurements were taken using measuring tools to ensure that the overall dimensional error was within the allowable range.

[0042] The pre-assembly process for section 102 rudder system components involves placing section 102 upside down on the jig, ensuring good contact between the upper deck surface and the jig bottom surface. The jig and section positions are then re-checked and calibrated. Precision surveyors use professional measuring instruments to mark the rudder line at rib #0, strictly adhering to measurement specifications to ensure accuracy. Two reference points are vertically marked, and clear, accurate midships markings are made using professional marking tools.

[0043] Two adjustable cable guides are installed above the rudder arm and inside the rudder compartment. During installation, the stability and verticality of the cable guides must be ensured. The rudder line is then pulled out using steel wire by adjusting the cable guides, and a total station is used for measurement and calibration to ensure the rudder line is perpendicularly bisected and precisely coincides with the segmented midships line. Multiple measurements and fine-tuning are required during adjustment to ensure the accuracy meets design requirements. According to the theoretical dimensions in the drawings, the rudder pin seat, lower rudder bearing, and upper rudder bearing are hoisted and positioned sequentially. During positioning, measuring tools are used to monitor and adjust the position of each component in real time to ensure that the relative positions and dimensions of each component meet design requirements. After positioning, the rudder pin seat is welded. Welding process parameters must be strictly controlled during welding to ensure welding quality. For the upper and lower rudder bearings, positioning marks are made but welding is not performed immediately to allow space for fine-tuning during subsequent assembly.

[0044] Implementation steps for closure monitoring

[0045] Before the hoisting of section 101, a comprehensive remeasurement of the hull's midships alignment and the gearbox main engine base's midships alignment was conducted using high-precision measuring instruments. During the remeasurement process, the measurement data was recorded and analyzed in detail, and any deviations were adjusted and corrected promptly.

[0046] When hoisting section 101, large lifting equipment was used to ensure a smooth and safe process. As the section approached its installation position, its position was slowly adjusted so that the midline of the stern tube support gradually aligned with the midline of the main engine base. During this alignment process, real-time monitoring was conducted using a total station to ensure that the alignment accuracy remained within the allowable range.

[0047] After the segment joints are aligned, the comb blocks are firmly spot-welded using specialized welding equipment. During spot welding, it is crucial to ensure welding quality and avoid issues such as incomplete welds or missed welds. Next, all the high piers on the hull below the segment are then supported and welded. Welding must be performed according to the welding process specifications to ensure weld strength and quality.

[0048] The data recorded during the measurement process is compiled and analyzed using professional data analysis software. The analysis includes the positioning accuracy of each component and the closure accuracy of each segment. Based on the analysis results, the accuracy of the closure and mounting data is determined. If deviations are found, adjustments and corrections are made promptly. Only when the closure and mounting data fully meet the design requirements can the 100-ton gantry crane hook be released to complete the hoisting operation.

[0049] During on-site construction, the amount of boring work was reduced because some key parts had already been processed in the workshop. On-site personnel operated according to the optimized process, improving efficiency while ensuring quality. Real-time monitoring of processing quality was conducted throughout the process; any problems identified were promptly adjusted and addressed.

[0050] When machining cast steel parts in the workshop, high-precision machining equipment is used to machine a relief groove according to design requirements for the deep steps in blind holes. During machining, machining parameters are strictly controlled to ensure the dimensional accuracy and surface quality of the relief groove. For the end cap sealing step groove, appropriate machining equipment is also used in the workshop. During machining, the dimensional and shape accuracy of the step groove must be guaranteed to meet design requirements.

[0051] This application significantly reduces the impact of variations in the assembly process and overlapping work on component positioning accuracy by pre-assembling the stern tube support and rudder system components on the sections and employing high-precision measurement and monitoring methods during the assembly process. Compared to traditional slipway installation methods, positioning accuracy is significantly improved. The forward shift of processes and technological improvements have yielded remarkable results.

[0052] Please refer to Figure 5 Taking the 693 container ship as an example, the installation cycle of the shaft and rudder system for ship #2 was shortened by 46.35% compared to ship #1, and ship #3 was shortened by another 27.28% compared to ship #2. The overall installation cycle of the shaft and rudder system on the slipway was shortened by ≥40%. This not only accelerated the turnaround speed of the slipway, but also laid a solid foundation for shortening the overall ship construction cycle and improved the shipyard's production efficiency.

[0053] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for pre-outfitting a stern shaft in sections, characterized in that, Includes the following steps: S1 and 101 segment stern tube support pre-installation: Invert the 101 segment stern tube support on the jig and mark each rib position. Then, the precision surveyor uses professional measuring tools and techniques to mark the axis 2300mm away from the baseline. Two reference points are vertically swept out by the plumb line and ground pattern marks are made. Then the cast steel part is hoisted in. The S2 and 102 section rudder system components are pre-assembled. The 102 section is installed in reverse on the jig, with the upper deck surface as the bottom surface of the jig and the rudder arm facing upward. The precision surveyor first marks the rudder line at the 0# rib position, and then sweeps two reference points vertically up and down to make the midship line mark. Then, the midship line is used to position each part. S3. Equipped with a closure monitoring system, the midship alignment of the hull and the midship alignment of the gearbox main engine base are re-measured before the 101 section is hoisted to ensure their accuracy; The high supports were hoisted one by one to the bottom of the ship to prepare for the installation of the 101 section. During the installation, the midship line of the stern tube support was precisely aligned with the midship line of the main engine base.

2. The stern shaft segment pre-outfitting method as described in claim 1, characterized in that: In step S1, marks are made on each rib position, from top to bottom as 5#, 6#, 7#, 8#, and 9#.

3. The stern shaft segment pre-outfitting method as described in claim 2, characterized in that: Using the 9# rib of the closure opening as the ground for the jig, with the stern closure opening facing upwards, a positioning plate is welded at the 9# rib. The cast steel stern tube support is then precisely hoisted into position, strictly controlling the overall dimensions according to the design requirements.

4. The stern shaft segment pre-outfitting method as described in claim 1, characterized in that: In step 2, two adjustable cable holders are erected above the rudder arm and inside the rudder compartment. The rudder line is pulled out using steel wire, and then a total station is used for measurement and correction to ensure that the rudder line is vertically bisected and coincides with the segmented midline. Then, the rudder pin seat, lower rudder bearing, and upper rudder bearing are positioned in sequence according to the theoretical dimensions in the drawings.

5. The stern shaft segment pre-outfitting method as described in claim 1, characterized in that: In step 2, after the welding of the 102 segment rudder pin seat is completed, the upper and lower rudder bearings are positioned but not welded yet. Fine adjustments will be made according to the actual situation when they are assembled.

6. The stern shaft segment pre-outfitting method as described in claim 1, characterized in that: In step 3, through precision measurement, the total station is set up in the cabin, sweeping across the midships point of the main engine gearbox base and extending to the stern tube support, to monitor the mounting process in real time.

7. The stern shaft segment pre-outfitting method as described in claim 1, characterized in that: In step 3, after the segmented seams are aligned, the comb is spot-welded securely.

8. The stern shaft segment pre-outfitting method as described in claim 7, characterized in that: The bottom of the ship below the section was supported by high blocks and welded together. Finally, the measurement data was collected and analyzed, and the gantry crane hook was released to complete the hoisting.

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