A C-LOOP sub-assembly general assembly jig and general assembly method for self-unloading ship
By modifying the shipyard's idle old assembly jigs, the problems of high jig manufacturing costs and long cycles in the conversion of large self-unloading ships were solved, realizing fast, economical, and safe C-LOOP section assembly, saving materials and time.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHENGXI SHIPYARD
- Filing Date
- 2026-04-21
- Publication Date
- 2026-06-16
Smart Images
Figure CN122211540A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of shipbuilding technology, specifically to a C-LOOP section assembly jig and assembly method for self-unloading ships. Background Technology
[0002] In the field of shipbuilding and repair, especially in the conversion of large self-unloading ships, the fabrication and installation of complex sections are often involved. For example, in a self-unloading ship conversion project, the C-LOOP section is a key structure with a total weight of over 500 tons. To accommodate the shipyard's lifting capacity, this section usually needs to be divided into multiple sub-sections for separate construction, and then assembled (i.e., the sections are joined together) to form a complete section, which is finally hoisted onto the ship as a whole.
[0003] In the final assembly stage, selecting a suitable assembly site and jig is crucial. Traditionally, there are two approaches: one is to assemble the sections piecemeal in a dry dock or slipway, sequentially hoisting each section onto the ship for assembly; the other is to perform intermediate assembly (pre-assembly of sections) at a dock or dedicated assembly platform before hoisting the entire section as a whole. For converted vessels, onboard space and construction schedules often present numerous limitations. For example, if assembly is done piecemeal onboard, the main deck section can only be hoisted after all interior work is completed, leading to excessively long waiting times for subsequent C-loop section installations and severely impacting the conversion cycle.
[0004] Therefore, reassembling the entire structure at the dock followed by overall hoisting is a better option. However, when assembling the entire structure on a roadbed site that meets load-bearing requirements, there is often no readily available jig foundation that matches the dimensions and shape of the entire section. To solve this problem, if a completely new dedicated jig is fabricated, it not only requires a large investment of steel (usually tens of tons) and auxiliary materials, leading to a sharp increase in costs, but the design, fabrication, and installation cycle of the jig (usually 7-10 days) will also prolong the entire conversion project's duration. Therefore, how to quickly, economically, and safely construct a jig that meets the requirements of C-LOOP segment assembly under limited conditions and resources has become a pressing technical challenge in this field. Summary of the Invention
[0005] The purpose of this invention is to overcome the defects in the prior art and provide a method for the assembly of C-LOOP sections of a heavy-duty self-unloading vessel based on the modification of an existing jig.
[0006] To achieve the above objectives, the technical solution of the present invention is to design a C-LOOP section assembly jig for a self-unloading ship, including a jig body, a support column assembly, a high-altitude section support structure, a reference positioning mark structure, and a pre-embedded component assembly. The main body of the jig is the old assembly jig after being cut and modified according to the C-LOOP segmented projection size. It retains the matching longitudinal and transverse beam frames and the upper surface beam panel, and the reinforcing ribs are welded at the junction of the longitudinal and transverse beam frames. The support column assembly includes multiple steel support columns. The top of the column is welded with a leveling pad and welded and fixed to the longitudinal and transverse beams on the reverse side of the frame body. The bottom is welded and connected to the embedded part assembly. The high-altitude segmented support structure consists of four rectangular steel columns located at the front end of the main frame, with horizontal connecting rods welded between adjacent columns. The reference positioning marking structure includes a center guideline, a rib reference line, and a horizontal reference rod sprayed on the upper surface of the tire frame; The embedded component is embedded in the foundation at a depth of not less than 800 mm.
[0007] Instead of manufacturing entirely new jigs, existing idle jigs at the shipyard were modified. The existing jigs were cut to match the geometry of the load-bearing area based on the projected dimensions of the target section, avoiding material waste from new jigs and significantly shortening the preparation cycle. Added support column assemblies lift the jig body off the ground and, through welding with embedded parts, form a stable whole, ensuring absolute stability for supporting 500-ton sections. Leveling pads at the top of the columns provide the structural foundation for subsequent precise leveling. The high-altitude segment support structure is specifically designed for potentially high or suspended sections at the front end of the C-LOOP section; its rectangular distribution and transverse connecting rods ensure the stability and integrity of the support. The benchmark positioning marker structure, through spraying center lines, rib lines, and setting horizontal markers, provides a clear and uniform benchmark for segment hoisting, crucial for achieving high-precision assembly. The minimum 800mm depth of the embedded parts ensures the connection strength and pull-out resistance with the foundation, meeting heavy-load requirements. This solution addresses the combined problems of limited space, high cost of jig manufacturing, and long production cycle.
[0008] Furthermore, the flatness error of the main beam panel on the upper surface of the jig body does not exceed 3 mm / m. The leveling shim is a steel shim with a thickness of 5-10 mm, used for fine-tuning the height of the support columns. The main beam panel, as the reference surface for direct support and positioning of the segments, has a flatness error of no more than 3 mm / m, which is fundamental to ensuring the overall alignment accuracy after subsequent splicing of multiple segments and reducing welding stress and deformation. The leveling shim, made of steel with a thickness of 5-10 mm, provides on-site construction personnel with a simple, efficient, and operable fine-tuning method. By adding, removing, or replacing shims of different thicknesses at the top of different support columns, accumulated errors such as uneven foundation and column height differences can be compensated, ultimately ensuring that the flatness of the entire jig panel meets the standards.
[0009] Furthermore, each column of the high-altitude segmented support structure is inclined with multiple auxiliary support rods at its bottom. These additional inclined auxiliary support rods at the bottom of each column form a triangular support structure, significantly enhancing the lateral stability and anti-overturning capacity of the columns. Since the high-altitude segments are typically located at or above the main section, they are heavy and have a high center of gravity, making them susceptible to lateral forces during hoisting and welding. The auxiliary support rods effectively transfer the bending moment and shear force borne by the columns to the ground or the main frame, ensuring the absolute safety and stability of the high-altitude segments during installation and welding.
[0010] Another technical solution of the present invention is to design a method for assembling C-LOOP sections of a self-unloading ship, the assembly method comprising the following steps: Step 1: Conduct structural inspection on the old main frame, cut and modify it according to the C-LOOP segmented projection dimensions, complete the modification of the main frame (1) and perform load-bearing calculation; Step 2: Place 12 1-meter square blocks (6) evenly in the gaps of the modified frame body (1), then hoist the frame body (1) onto the square blocks (6), and set at least 2 horizontal reference rods (43) on the outside to complete the initial leveling of the frame body (1) using the square blocks (6). Step 3: Based on the structure of the main body (1) of the jig and the weight distribution of the C-LOOP segments, install the support column assembly (2), weld and fix it, remove the square block (6), fine-tune the leveling pad (22) so that the flatness error of the main body (1) of the jig does not exceed 3mm / m, and fully weld the bottom of the column to the embedded part assembly (5). Step 4: Use a laser line projector to draw the center guideline (41) and rib reference line (42) on the upper surface of the main body (1) of the frame, mark the weight distribution mark, complete the production of the reference positioning mark structure (4) and check the accuracy; Step 5: Install the high-altitude segmented support structure (3) at the front end of the main body of the frame (1); Step 6: Conduct an overall acceptance inspection of the main assembly frame. After the inspection is passed, hoist 13 C-LOOP segments (7) according to the principle of "bottom first, top second, main first, secondary second". Position them precisely according to the benchmark positioning mark structure (4), spot weld them temporarily, and then weld them fully to complete the segment assembly. Step 7: The C-LOOP section completed by the general team is inspected and accepted. After passing the inspection, the whole section is hoisted onto the ship for closure. Then the frame is removed and the main body of the frame (1) is repaired and restored.
[0011] Furthermore, in step 6, the splicing gap error of the C-LOOP segments does not exceed 1 mm. After each segment is positioned, jacks and hand-operated hoists are used for fine-tuning of its position and level. Maintaining a splicing gap error of no more than 1 mm aims to ensure weld quality, reduce welding deformation, and guarantee the overall alignment of the entire segment. To achieve this precision, after segment positioning, jacks and hand-operated hoists are used for fine-tuning of position and level. Jacks are mainly used for vertical adjustment, while hand-operated hoists are used for horizontal alignment and tightening. These two tools are commonly used simple tooling in shipyards, offering flexible operation and enabling millimeter-level fine-tuning. This feature solves the problem of insufficient splicing accuracy caused by the difficulty in precisely fine-tuning large segments after hoisting and positioning.
[0012] Furthermore, in step 6, after welding, the weld is subjected to ultrasonic testing (UT) and magnetic particle testing (MT). The deformation of the completed C-LOOP segment should not exceed 3 mm / m. UT ultrasonic testing is used to detect internal defects in the weld, such as porosity, slag inclusions, and incomplete penetration; MT magnetic particle testing is used to detect surface and near-surface defects in the weld, such as cracks and undercut. The combined use of these two non-destructive testing methods can comprehensively assess the welding quality of the weld and ensure the safety of the overall structure. The overall segment deformation not exceeding 3 mm / m is the final inspection of the overall assembly process and a key indicator to ensure smooth docking of the segment with the ship during closure.
[0013] Furthermore, in step 7, after the jig is removed, the main body of the jig is ground and repaired to remove welding residue and burrs, ensuring that its original appearance remains largely unchanged and its original function is unaffected. After the jig is removed, residues and burrs left from welding columns and supports are removed by grinding, and any minor damage is repaired. The purpose is to ensure that the core attributes of the jig, such as its structural shape and dimensional accuracy, remain largely unchanged after modification and use, so that it can be put back into use and perform its original function.
[0014] The advantages and beneficial effects of this invention are as follows: This invention directly utilizes existing, idle assembly jigs in the shipyard for modification, avoiding the investment of approximately 50 tons of steel and auxiliary materials required to manufacture a new large jig, thus greatly reducing tooling costs. Simultaneously, since there is no need for complex new jig design, procurement, and manufacturing, corresponding labor and material costs are also saved. The modification work of the old jig is carried out in parallel with the assembly preparation work, with a modification cycle of only 1-2 days, compared to the at least 7-10 days for manufacturing a new jig, saving more than a week of valuable time. This is of great significance for modification projects with tight schedules, allowing for better control over subsequent key processes such as onboard assembly. Through rigorous load-bearing calculations, the installation of stable support column components (including leveling pads and embedded parts connections), and the addition of a special support structure with auxiliary support rods for high-altitude sections, this invention ensures the load-bearing capacity and stability of the jig throughout the assembly process, providing a safe and reliable platform for the hoisting, positioning, and welding operations of 500-ton large sections. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the old main frame and the part to be cut in this invention; Figure 2 This is a schematic diagram of the overall frame and square pier of the present invention; Figure 3 This is a schematic diagram of the structure of the present invention, showing the placement of the main frame onto the square pier; Figure 4 These are the top view and front view of the overall frame of the present invention; Figure 5 These are the front view, left view, and top view of the C-LOOP segmentation of this invention.
[0016] In the diagram: 1. Main frame; 11. Longitudinal and transverse beam frame; 12. Upper surface beam panel; 2. Support column assembly; 21. Support column; 22. Leveling pad; 3. High-altitude segmented support structure; 31. Column; 32. Auxiliary support rod; 33. Transverse connecting rod; 4. Benchmark positioning marker structure; 41. Center line; 42. Rib benchmark line; 43. Horizontal benchmark marker; 5. Embedded component assembly; 6. Square pier; 7. C-LOOP segment; 8. Foundation. Detailed Implementation
[0017] 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.
[0018] As attached Figure 1 As shown, the unused frame was originally used for building ship superstructures; it is structurally complete and relatively large.
[0019] The overall assembly frame of the present invention mainly includes a frame body 1, a support column assembly 2, a high-altitude segmented support structure 3, a reference positioning mark structure 4, and a pre-embedded component assembly 5.
[0020] Main body of the frame 1: such as Figure 1 As shown, the main body 1 of the frame is the core part of the modified old frame. First, based on the projected dimensions of the C-LOOP segment, technicians marked lines on the old frame, and then used a plasma cutter or flame cutter to remove excess structural parts. The remaining portion has its longitudinal and transverse beam frames 11 and upper surface beam panels 12 arranged to match the main load-bearing areas and overall shape of the C-LOOP segment. To ensure sufficient strength and rigidity of the modified frame under heavy loads, additional reinforcing ribs are welded at the intersection points of the longitudinal and transverse beam frames 11. These reinforcing ribs are typically made of steel plates of the same material as the base material, with a thickness of 12 mm to 20 mm, and are triangular or rectangular in shape, arranged along the diagonal or vertical direction of the intersection points, effectively enhancing the bending and shear resistance of the joints.
[0021] Support column assembly 2: such as Figure 4 As shown, the support column assembly 2 consists of multiple steel support columns 21 and leveling pads 22. The number and position of the support columns 21 are calculated and determined based on the weight distribution of the C-LOOP segment (500 tons) and the layout of the longitudinal and transverse beam frames 11 of the main body 1 of the jig, totaling approximately 20-30 columns. Each support column 21 is made of Q235B or Q345B H-beams or seamless steel pipes, with a cross-sectional dimension of not less than 200 mm × 200 mm and a wall thickness of not less than 10 mm to ensure sufficient load-bearing capacity. A leveling pad 22 is first welded to the top of the column 21. The leveling pad 22 is a rectangular steel plate with a thickness of 5 mm to 10 mm, and its area is slightly larger than the cross-section of the top of the column. Its function is to provide a precise leveling plane. Subsequently, the top of the column 21 is firmly welded to the longitudinal and transverse beam frames 11 on the reverse side of the jig main body 1 through the leveling pad 22. The bottom end of the column 21 is fully welded to the pre-embedded component 5 that is pre-embedded in the foundation 8 to form a stable rigid support system.
[0022] High-altitude segmented support structure 3: such as Figure 5As shown, considering the presence of a complex segment at a relatively high position at the front end of the C-LOOP section, this embodiment incorporates a high-altitude segment support structure 3 at the front end of the main frame 1. This structure consists of four rectangular steel columns 31, which are also constructed using high-strength H-beams or seamless steel pipes. To enhance lateral stability, four auxiliary support rods 32 are welded obliquely around the bottom of each column 31. The other ends of the auxiliary support rods 32 are fixed to the foundation or the longitudinal and transverse beams of the main frame 1, forming a triangular support structure. Furthermore, transverse connecting rods 33 are welded between adjacent columns 31 at certain heights from the ground (e.g., 1.5 meters and 3 meters), connecting the four columns into a single frame, further enhancing its resistance to torsion and lateral forces. This structure provides a stable and reliable support point for the high-altitude segment.
[0023] Reference positioning mark structure 4: such as Figure 4 , 5 As shown, the reference positioning marker structure 4 serves as a visual reference to ensure accurate segment positioning. It includes a centerline 41 and rib reference lines 42 painted on the main beam panel 12 of the jig body 1, as well as horizontal reference poles 43 set on the outside of the jig. The centerline 41 is the longitudinal centerline of the entire segment, and the rib reference lines 42 are the position lines of each major transverse frame structure. These lines are drawn using a high-precision laser line projector, with a line width controlled within 1 mm, and are painted with conspicuous red or white paint. The horizontal reference poles 43 are typically slender round steel or angle steel welded to the outside of the jig, and their tops are uniformly checked to the same horizontal height using a level, providing a reference for jig leveling and segmental levelness measurement.
[0024] Embedded component assembly 5: such as Figure 4 As shown, the embedded component 5 is pre-installed during construction at the selected site. Each embedded component 5 includes a thick steel plate and several anchor bars. The thick steel plate is 300 mm × 300 mm in size and 20 mm thick, serving as the connection surface for welding with the supporting column 21. The anchor bars are welded to the back of the steel plate, extending deep into the foundation 8 to a depth of not less than 800 mm, and are tied to the reinforcing mesh within the foundation. After concrete is poured, this creates strong tensile and shear resistance.
[0025] The method for C-LOOP segmentation assembly using the above-mentioned jig includes the following steps: Step 1: As Figure 1 As shown, old tire frame assessment and modification First, a comprehensive structural inspection was conducted on the selected old formwork from the main construction group. The inspection included checking all beams, columns, and connecting plates for obvious corrosion, cracks, or permanent deformation; measuring its overall dimensions and the flatness of the upper beam panel 12. After confirming the structure's integrity, the projected outline of the formwork was marked with chalk lines according to the detailed design drawings of the C-LOOP section. Then, using a semi-automatic flame cutter or plasma cutter, cut along the outline 50 mm outside, removing excess material to form the main formwork 1. After the modification, technicians used finite element analysis software to perform load-bearing calculations on the modified main formwork 1 and its support scheme, based on the 500-ton weight and distribution of the C-LOOP section, ensuring that the maximum stress value was lower than the allowable stress of the material and that the safety factor met the requirements (usually not less than 1.5).
[0026] Step 2: As Figure 2 , 3 As shown, the tire frame is initially positioned and roughly adjusted. On the selected load-bearing roadbed site in the western shipbuilding area, pre-embedded components 5 are pre-installed in the foundation 8 according to the dimensions of the main frame 1 and the layout of the supporting columns 21. Twelve 1-meter-high steel square piers 6 are evenly placed in the gaps between the longitudinal and transverse beam frames 11 of the main frame 1. The tops of the square piers 6 should be on the same horizontal plane. Then, using lifting equipment (such as a truck crane), the modified main frame 1 is lifted as a whole and placed stably on the square piers 6. On the outer side of the main frame 1, at least two diagonal positions are selected to weld horizontal reference rods 43. Using a high-precision level, with the horizontal reference rods 43 as a reference, the upper surface beam panel 12 of the main frame 1 is initially adjusted to a basic level by adjusting the shims below or above the square piers 6.
[0027] Step 3: Installation and fine-tuning of support columns Based on the node positions and calculation results of the longitudinal and transverse beam frames 11 of the main frame 1, the installation points of the support columns 21 are determined. The prefabricated support columns 21 (with leveling pads 22 welded to their tops) are hoisted to the corresponding positions, and their tops are spot-welded to the longitudinal and transverse beam frames 11 on the reverse side of the main frame 1 via the leveling pads 22. After all columns 21 are spot-welded, the square piers 6 are removed one by one using lifting equipment, so that the weight of the main frame 1 is entirely borne by the support columns 21. At this point, a level is used again, with the horizontal reference rod 43 as the benchmark, to measure the elevation of multiple feature points on the main beam panel 12. Based on the measurement results, the main beam panel 12 is precisely leveled by changing or adjusting the thickness of the leveling pads 22, ensuring that its flatness error does not exceed 3 mm / m. After fine-tuning, the bottom ends of all support columns 21 are fully welded to the steel plates of the embedded component assembly 5. At the same time, the weld between the top of the column 21 and the main body of the jig is changed from spot welding to full welding to ensure that all connections are firm and reliable.
[0028] Step 4: Establish a precise positioning benchmark After the jig is finely adjusted and fixed, a high-precision laser line projector is used to mark lines on the upper surface of the jig body 1, on the main beam panel 12. First, based on the design data of the C-LOOP segment, the longitudinal center line of the entire segment is projected, marked with a chalk line, and sprayed with red paint to form the center guideline 41. Then, using the center guideline 41 as a reference, transverse rib lines are projected at regular intervals (such as one rib spacing), marked with a chalk line, and sprayed with white paint to indicate the rib number, forming the rib reference line 42. At the same time, weight distribution markings are sprayed at the corresponding segment center of gravity to indicate safety precautions during hoisting. After all lines are completed, the positional accuracy of the reference lines is checked using a steel ruler and a theodolite to ensure that the deviation is within the allowable range.
[0029] Step 5: Install the high-altitude segmented support structure According to the overall assembly process requirements, the high-altitude segment support structure 3 is installed at the corresponding position at the front end of the main frame 1. First, the bottom ends of the four columns 31 are welded and fixed to the embedded parts on the foundation 8, and auxiliary support rods 32 are welded. Then, horizontal connecting rods 33 are welded between the columns 31 according to the design positions. After installation, the verticality, horizontality, and overall stability of the support structure are checked to ensure that it can safely support the high-altitude segment to be hoisted.
[0030] Step 6: Segmented hoisting and overall assembly The overall jig undergoes final acceptance testing, inspecting all welds, connections, and baselines. Once everything is confirmed to be correct, segmented hoisting begins. Following the principle of "bottom first, top second; main first, secondary third," the 13 C-LOOP segments 7 are hoisted sequentially. During hoisting, the crane operator guides the segments, aligning their center lines and rib lines with the center alignment line 41 and rib baseline line 42 on the jig. After initial positioning, operators use jacks and chain hoists to fine-tune the segment's position and level. For example, screw jacks are used to lift the segment from below to adjust its height, and chain hoists are used to pull the segment laterally to adjust its horizontal position, until the gap error between adjacent segments does not exceed 1 mm. After precise positioning, temporary fixation is achieved by spot welding using high-strength clamps, followed by full welding by certified welders according to the welding procedure specifications. After all welds are completed, non-destructive testing is performed, including UT ultrasonic testing for all full penetration welds and MT magnetic particle testing for all fillet welds. Throughout the entire assembly process, the deformation of the main section is monitored regularly to ensure that it does not exceed 3 mm / m.
[0031] Step 7: Main section hoisting and jig restoration After all segment welding and testing are completed, and the entire section is assembled, a final dimensional and visual inspection is conducted. Upon passing inspection, a 1600-ton floating crane is used to lift the C-LOOP section, weighing over 500 tons, from the jig and transport it to a dry dock or wharf for closure with the main body of the self-unloading vessel. After fulfilling its purpose, the jig is immediately dismantled. First, air gouging or carbon arc gouging is used to remove the welds connecting the support column 21 to the embedded component 5 and the jig body 1. Then, the column 21, the high-altitude segment support structure 3, and other components are lifted away. Finally, the surface of the jig body 1 is thoroughly ground to remove all welding residue, spatter, and burrs, and any minor deformations are corrected. After repair, the structure and dimensions of the jig body 1 are essentially restored to their original state, and its original function (such as for use in other superstructure assemblies) remains unaffected, allowing it to be put back into service.
[0032] 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 C-LOOP section assembly jig for a self-unloading ship, characterized in that, It includes the main body of the frame (1), the support column assembly (2), the high-altitude segmented support structure (3), the benchmark positioning mark structure (4), and the embedded part assembly (5); The main body (1) of the jig is the old assembly jig after being cut and modified according to the C-LOOP segmented projection size. It retains the matching longitudinal and transverse beam frames (11) and the upper surface beam panel (12). The longitudinal and transverse beam frames (11) are welded with reinforcing ribs at the junction. The support column assembly (2) includes multiple steel support columns (21), with a leveling pad (22) welded to the top of the column and welded and fixed to the longitudinal and transverse beams on the reverse side of the frame body (1), and the bottom end welded to the embedded part assembly (5). The high-altitude segmented support structure (3) consists of four rectangular steel columns (31) located at the front end of the frame body (1), with transverse connecting rods (33) welded between adjacent columns (31). The reference positioning mark structure (4) includes a center guideline (41), a rib reference line (42), and a horizontal reference rod (43) sprayed on the upper surface of the jig body (1); The embedded component (5) is embedded in the foundation (8) at a depth of not less than 800mm.
2. The self-unloading ship C-LOOP section assembly jig according to claim 1, characterized in that, The flatness error of the upper surface beam panel (12) of the main body (1) of the frame does not exceed 3mm / m. The leveling pad (22) is a steel pad with a thickness of 5-10mm, which is used to finely adjust the height of the support column (21).
3. The self-unloading ship C-LOOP section assembly jig according to claim 1, characterized in that, The bottom end of each column (31) of the high-altitude segmented support structure (3) is provided with multiple auxiliary support rods (32).
4. A method for assembling a self-unloading vessel C-LOOP section assembly jig adapted to any one of claims 1-3, characterized in that, The overall grouping method includes the following steps: Step 1: Conduct structural inspection on the old main frame, cut and modify it according to the C-LOOP segmented projection dimensions, complete the modification of the main frame (1) and perform load-bearing calculation; Step 2: Place 12 1-meter square blocks (6) evenly in the gaps of the modified frame body (1), then hoist the frame body (1) onto the square blocks (6), and set at least 2 horizontal reference rods (43) on the outside to complete the initial leveling of the frame body (1) using the square blocks (6). Step 3: Based on the structure of the main body (1) of the jig and the weight distribution of the C-LOOP segments, install the support column assembly (2), weld and fix it, remove the square block (6), fine-tune the leveling pad (22) so that the flatness error of the main body (1) of the jig does not exceed 3mm / m, and fully weld the bottom of the column to the embedded part assembly (5). Step 4: Use a laser line projector to draw the center guideline (41) and rib reference line (42) on the upper surface of the main body (1) of the frame, mark the weight distribution mark, complete the production of the reference positioning mark structure (4) and check the accuracy; Step 5: Install the high-altitude segmented support structure (3) at the front end of the main body of the frame (1); Step 6: Conduct an overall acceptance inspection of the main assembly frame. After the inspection is passed, hoist 13 C-LOOP segments (7) according to the principle of "bottom first, top second, main first, secondary second". Position them precisely according to the benchmark positioning mark structure (4), spot weld for temporary fixation, and then fully weld to complete the segment assembly. Step 7: The C-LOOP section completed by the general team is inspected and accepted. After passing the inspection, the whole section is hoisted onto the ship for closure. Then the frame is removed and the main body of the frame (1) is repaired and restored.
5. The method for assembling C-LOOP sections of a self-unloading vessel according to claim 4, characterized in that, In step 6, the splicing gap error of the C-LOOP segment (7) shall not exceed 1mm. After each segment is positioned, a jack and a hand-operated hoist shall be used to make fine adjustments to its position and level.
6. The method for assembling C-LOOP sections of a self-unloading vessel according to claim 5, characterized in that, In step 6, after welding is completed, the weld is subjected to UT ultrasonic testing and MT magnetic particle testing. The deformation of the C-LOOP segment completed by the group does not exceed 3mm / m.
7. The method for assembling C-LOOP sections of a self-unloading vessel according to claim 5, characterized in that, In step 7, after the jig is removed, the jig body (1) is polished, repaired, and welding residues and burrs are removed.