Method for controlling construction precision of thin film type fuel cabin of LNG (Liquefied Natural Gas) power-driven ship

Abstract

The invention discloses a construction precision control method for a thin film type fuel cabin of an LNG power-driven ship. The construction precision control method comprises the following steps that main plate pieces of the thin film cabin are segmented, the flatness is controlled, T rows are segmented and prefabricated, and main body plate pieces obtained by segmenting the plate pieces and other assemblies are subjected to component splicing, storage and transportation. Splicing a plurality of sections related to the thin film cabin, assembling the sections after splicing, and welding the sections; and carrying out total assembling and carrying on the segments according to a standard base line, and controlling local and overall flatness of the segments. Through whole-process precision control, it is ensured that the flatness of the inner surface of the film cabin meets the high-standard requirement; a special jig frame, non-welding fixation, symmetrical welding and other measures are adopted, and welding and assembling deformation is effectively restrained; and the construction efficiency is improved, rework is reduced and the production efficiency is improved by using a standardized process and a special tool.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of shipbuilding, in particular to a thin-film fuel tank construction precision control method for an LNG-powered ship. BACKGROUND

[0002] With the wide application of LNG fuel on large container ships, the thin-film tank, as the core structure of the LNG fuel system, has very high construction precision requirements. In the traditional construction method, due to factors such as welding thermal deformation, uneven lifting, insufficient structural rigidity and the like, the inner surface flatness of the thin-film tank is difficult to meet the technical requirement of <=4mm / 3m, which causes the tank wall flatness to be higher than the standard, and affects the installation and sealing performance of the subsequent thin-film system. Especially in 8000TEU large ships, the thin-film tank structure is complex, the number of sections is large, and the control surface is large, so the existing technology is difficult to meet the local and overall flatness requirements. SUMMARY

[0003] The application provides a thin-film fuel tank construction precision control method for an LNG-powered ship, which effectively controls the deformation of the thin-film tank structure during the construction process and ensures the inner surface flatness and high precision.

[0004] The technical scheme is as follows: S1, the main plate of the thin-film tank is segmented and the flatness is controlled, the T row is segmented and prefabricated, and the main plate obtained by segmenting the plate and other components are assembled and stored and transported; S2, the plurality of segments involved in the thin-film tank are spliced, and after completion, the segments are welded; S3, the segments are assembled and carried according to the standard baseline, and the local and overall flatness is controlled.

[0005] Further, S1 specifically includes: S1-1, after the numerical control cutting of the main plate, the stress is released through a rolling machine, the plate stacking and circulation adopt a special tray, the stacking is performed from large to small, the processed plate is placed on a flat ground, the number of stacking layers is controlled, and deformation caused by uneven stress is avoided; during the splicing operation, a counterweight pressing iron is used to suppress the angular deformation of welding; S1-2, during the prefabrication of the T row, the straightness of the panel and the web after cutting is checked, the out-of-tolerance components are corrected, the T profile assembly is completed on a flat platform, the lateral bending deformation is rechecked and corrected after forming, and the qualified products flow into the section assembly process; S1-3, the component assembly is implemented on a flat site, a positioning baffle is arranged on the side, straightness is checked before profile assembly, and assembly gap is controlled; the component assembly is placed on a special bracket for storage and transportation after forming, a wooden block is added to the weak structure part to ensure flatness, and if it is inconvenient to stack and store, an independent bracket is used for transportation; S1-4, the main plate is transported by electromagnetic lifting, and when the finished product is lifted on the bracket, multi-point lifting is adopted according to the characteristics of the assembled part to disperse the stress points; S1-5, the flatness of the plate surface meets the standard, and there is no hard bending deformation, the straightness tolerance of the T-shaped profile is 1m±1mm, the lateral bending deviation of the rib plate, longitudinal girder and longitudinal wall in the assembled structure is ≤4mm within the whole factory, and the resistance flatness tolerance of the hard file position is ≤2mm.

[0006] Further, S2 includes segmented plate splicing, segmented sub-section assembly, segmented total assembly, segmented welding, segmented transportation and segmented precision process control, and specifically comprises: S2-1, the segmented plate splicing operation is implemented on a special jig frame, the upper surface of the jig frame is free of welding scar protrusions, the plate material overhanging area is leveled by using a wooden block pad, when the welding seam ends overhang the jig frame or are not in the strong file position of the jig frame, a wooden block support is added during welding, and for the plate splicing involving thick plates, a pressing iron is directly used on both sides of the welding seam to apply forced constraint to control welding deformation; S2-2, straightness of the assembled parts is checked before assembly; the assembly gap of the parts is as small as possible, and a non-welding method is used; after assembly and welding are completed, the structure is annealed to release the stress generated during assembly and welding; S2-3, segmented total assembly, plate splicing is implemented on a special plate splicing jig frame, the segmented jig frame uses an angle steel jig frame, a numerical control square plate is attached, the upper surface is free of cutting, the jig frame height is required to be ±2mm, and support templates are arranged on the free plate edges of the upper plate around the jig frame to ensure the flatness of the plate edges; the upper plate of the plate is ensured to be attached to the jig frame, when multiple plates are attached, the welding seams between the plates are welded by automatic submerged arc welding, and the other side is welded and left for automatic submerged arc welding after the segmented turning over; in order to reduce the assembly and welding deformation, a “7” shaped clamping plate or a non-welding method is used for fixation; S2-4, the welding sequence adopts self-centering and four-directional radial welding and symmetrical skip welding; during segmented structure welding, two welders are used to symmetrically weld along the segmented central axis, the butt welding seam between the frames is first completed, then the vertical fillet welding seam between the frames is welded, and finally the horizontal fillet welding seam between the frames and the plate frame is completed; during vertical fillet welding, the upper welding seam is first completed, and then the lower welding seam is welded; S2-5, after the segmented plate is turned over to the outside field after the segmented plate is lowered, the segmented plate is adjusted horizontally before welding, if it cannot be leveled, whether the segmented plate is twisted is confirmed by using a total station, and welding operation is performed when it is confirmed that the twisting degree is controlled within 10mm; S2-6, After the segmented under the tire, the fire before the translation to the field still need a lot of back heating and pyrotechnic correction of the segment, adjust to the horizontal state and use tool support, prevent the deformation of the fire; S2-7, After the segmented under the tire, support and rest on the pier for large engine room tail, head, transverse bulkhead segment, segment out of the distance of the horse pier is too large or the support strength of the horse pier is insufficient, timely feedback process method, cooperate with the method to increase the support point and strengthen, prevent deformation.

[0007] Further, in S3, the total segment is pre-assembled, and the overall level is controlled within ±7mm, and the half-width deviation is ≤4mm, with the center line, horizontal line, and distance from the line as the reference.

[0008] Further, in S3, the local flatness of the inner surface of the membrane cabin is required to be 4mm / 3m, and the overall flatness standard is 8mm for segmented stages or 14mm for total stages.

[0009] Further, it includes the following segments: left side bottom support structure, right side bottom support structure, left side bottom corner support structure, right side bottom corner support structure, left side wall support structure, right side wall support structure, left side top corner support structure, right side top corner support structure, left side top support structure, right side top support structure, left side membrane structure, and right side membrane structure.

[0010] Further, the left side bottom support structure and the right side bottom support structure segment precision process control, first with the inner bottom as the base surface to form the inner bottom segment by reversing the plate body, and then turn over to install the transverse bulkhead structure with the plate as the base surface; The left side bottom corner support structure and the right side bottom corner support structure segment precision process control, with the membrane cabin inclined plate as the base surface, and a total of 3 sub-segment assemblies and 3 side pieces segments are formed; The left side wall support structure and the right side wall support structure segment precision process control, with the membrane cabin inner longitudinal wall top frame as a sub-segment assembly, with the inner longitudinal wall within 20470mm from the keel as the base surface to form a sub-segment assembly with plate, and then turn over to install the membrane cabin inner longitudinal wall and transverse bulkhead structure with the plate as the base surface to form a complete segment; The left side top corner support structure and the right side top corner support structure segment precision process control, with the main deck as the base surface to reverse, composed of 2 transverse bulkhead sub-segment assemblies, inner longitudinal wall sub-segment assemblies within 20470mm from the keel, isolation cabin bottom plate sub-segment assemblies, and membrane cabin inclined top plate sub-segment assemblies; The left side top support structure and the right side top support structure segment precision process control, with the main deck as the base surface to reverse, composed of isolation cabin sub-segment assemblies and 2 transverse bulkhead sub-segment assemblies; The left side thin film structure segment precision process control is made with the bow end face as a base surface, the tail end wall plate is made on a flow line, and the segment is turned over with the tail end wall as a base surface on a horse block; the right side thin film structure segment is made with the tail end face as a base surface, the bow end wall plate is made on a flow line, and the segment is turned over with the bow end wall as a base surface on a horse block.

[0011] Further, S3 includes left side cabin bottom total segments, right side cabin bottom total segments and cabin top total segments, and the left side cabin bottom total segments and the right side cabin bottom total segments are implemented to be pre-joined and total groups; The left side cabin bottom total segments and the right side cabin bottom total segments are pre-joined normal total groups, and the right side bottom support structure total group is positioned with the center line of the left side bottom support structure segment as a reference; The left side bottom corner support structure and the right side bottom corner support structure total group are positioned and adjusted with the left side bottom support structure and the right side bottom support structure segment as a reference; The left side thin film structure and the right side thin film structure total group are positioned and joined with the center line of the left side bottom support structure and the right side bottom support structure and the horizontal line as a reference; The left side top support structure and the right side top support structure total group is positioned with the center line of the right side top support structure segment as a reference, and the horizontal line is adjusted in the segment stage; The left side top corner support structure and the right side top corner support structure total group is positioned with the left side top support structure and the right side top support structure segment as a reference for adjustment; The left side cabin bottom total segment is implemented to be joined with the center line of the ground sample, the right side cabin bottom total segment is joined with the left side cabin bottom total segment total segment horizontal line, center line and joining seam line reference, and the cabin top total segment is joined with the center line, horizontal line and distance base height line as a reference.

[0012] Beneficial effects: compared with the prior art, the present application has the following obvious advantages: through the whole process precision control, the flatness of the thin film cabin inner surface is ensured to meet the high standard requirement; special jig, non-welding fixation, symmetrical welding and other measures are adopted to effectively inhibit the welding and assembly deformation; the use of standardized process and special tooling improves the construction efficiency, reduces the rework and improves the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a thin film cabin segment schematic diagram of the present application; Figure 2 is a jig angle steel and numerical control square plate fitting schematic diagram of the present application; Figure 3 is a thin film cabin bottom support structure precision control reference schematic diagram of the present application; Figure 4 is a thin film cabin each segment structure schematic diagram of the present application; Figure 5 is a thin film cabin loading schematic diagram of the present application; Figure 6 is a DAP drawing for constructing the bottom corner support structure of the film cabin. DETAILED DESCRIPTION

[0014] The technical solutions of the present application will be further described below in combination with the drawings and examples.

[0015] A LNG-powered ship film fuel cabin construction precision control process, comprising the following steps: S1, a film cabin processing and manufacturing precision control process, the main plate of the film cabin is segmented, and the flatness is controlled, the T row is segmented and prefabricated, the main plate obtained by segmenting the plate and other components are assembled, and stored and transported; S2, a film cabin segment construction precision control process, the 12 segments involved in the film cabin are assembled, and the segments are welded after assembly is completed; S3, a film cabin total assembly and mounting precision control process, the above segments are assembled and mounted according to the standard baseline, and the local and overall flatness is controlled.

[0016] Among them, the film cabin processing and manufacturing precision control process comprises the following steps: S1-1, as shown in Figure 1 The main plate is segmented, including: left side bottom support structure 1, right side bottom support structure 2, left side bottom corner support structure 3, right side bottom corner support structure 4, left side wall support structure 5, right side wall support structure 6, left side top corner support structure 7, right side top corner support structure 8, left side top support structure 9, right side top support structure 10, left side film structure 11, right side film structure 12; The main plate must be placed on a flat ground, and the number of layers should be strictly controlled to avoid deformation caused by uneven stress; After the main plate is cut by numerical control, the flatness is checked, and the large deviation needs to be released by a rolling machine; The plate is stacked on the transfer segment using a special tray, and the stacking structure principle of large below and small above is followed; During the plate assembly operation, the plate is naturally fitted with the plate assembly jig in a flat state, the plate joint must be padded during electric welding, and counterweight pressing iron must be used to suppress the deformation of the welding angle.

[0017] S1-2, the T row is segmented, including: left side bottom support structure 1, right side bottom support structure 2, left side bottom corner support structure 3, right side bottom corner support structure 4, left side wall support structure 5, right side wall support structure 6, left side top corner support structure 7, right side top corner support structure 8, left side top support structure 9, right side top support structure 10, left side film structure 11, right side film structure 12; The straightness of the T row panel and web is checked and corrected; The T row manufacturing platform needs to be flat, after the profile prefabrication is completed, it needs to be corrected again to qualified, and special trays are used to place neatly to avoid uneven stress.

[0018] S1-3, the component assembly needs to be implemented on a flat site, and positioning baffle is arranged on the side to fix; before the profile assembly, the straightness of the profile needs to be checked, and the assembly can be performed only when the requirement is met, and the assembly gap is strictly controlled, and the excess height of the profile needs to be ground flat; after the component assembly is formed, the component assembly is placed on a special bracket for storage and transportation, and wooden pads need to be added to the weak structure part to ensure flatness. If there is a significant structure protrusion which is not convenient for stacking and storing, an independent bracket needs to be used for transportation.

[0019] S1-4, the main plate transport should use electromagnetic lifting to lift, and single-point lifting is strictly prohibited; when the finished product is lifted on the bracket, multiple-point lifting should be adopted according to the characteristics of the assembled part to disperse the stress points.

[0020] S1-5, the flatness of the plate surface should meet the standard requirement, and there should be no hard bending deformation, the straightness tolerance of the T profile is 1 m ± 1 mm, the side bending deviation of the rib plate, longitudinal girder and longitudinal wall in the assembled structure should be ≤4 mm in the full length range; the hard file position tolerance of the resistance flatness should be ≤2 mm.

[0021] The thin film cabin segmented construction control process includes segmented plate splicing, segmented sub-section assembly, segmented assembly, segmented welding, segmented moving and transporting and segmented precision process control, and involves 12 segments: left side bottom support structure 1, right side bottom support structure 2, left side bottom corner support structure 3, right side bottom corner support structure 4, left side side wall support structure 5, right side side wall support structure 6, left side top corner support structure 7, right side top corner support structure 8, left side top support structure 9, right side top support structure 10, left side thin film structure 11 and right side thin film structure 12; the thin film cabin horizontal requirement is 4 mm / 3 m, the segmented single surface flatness standard is 8 mm for a total of 10 surfaces, including the following steps: S2-1, the segmented plate splicing operation should be implemented on a special jig, and the upper surface of the jig should be free of welding scar protrusions; before the segmented plate splicing, the flatness of the plate should be checked; the overhanging area of the plate needs to be leveled by using wooden blocks, when the welding seam ends overhang the jig or are not in the strong file position of the jig, supporting wooden blocks need to be added during the welding process to avoid significant welding corner deformation; for the plate splicing involving thick plates, forced constraints can be directly applied on both sides of the welding seam by using pressing iron to control the welding deformation.

[0022] S2-2, when the segmented sub-section is assembled, the segment needs to be placed on a flat jig; before the parts are assembled, the straightness thereof should be checked, and the parts that do not meet the deviation requirement should be returned to the machining workshop; the assembly gap of the parts should be as small as possible, and non-welding methods such as magnetic attraction horse or pressing iron are used during the assembly; after the assembly of the parts is completed, the structure position is annealed by turning over to release the stress generated during the assembly and welding.

[0023] S2-3, the segmented assembly, the plate splicing should be implemented on a special plate splicing jig; if Figure 2As shown, the segmented jig uses an angle steel jig 13, with a CNC square plate 14 attached. Cutting of the upper surface is prohibited. The jig height requirement is ±2mm. Support templates should be installed around the free edges of the upper jig plate extending beyond the jig to ensure the flatness of the plate edges. During segmented assembly, the dimensions, shapes, and quantities of components and assemblies should be checked against the drawings; forced assembly is prohibited. The upper jig plate should fit snugly against the jig. When multiple plates are mounted, the welds between the plates should be done using submerged arc welding. The welding on the other side should be completed by submerged arc welding after the segment is flipped. The jig plate is fixed to the jig using a "7"-shaped clamp or a non-welded clamp. The clamping should be adjusted according to the actual segmentation. Additional measures are required. Direct welding of iron bars to the jig plate and jig is strictly prohibited. Welding jig supports onto the outer plate is not allowed. T-beams and bulkheads should be installed with a "zero gap". When installing plates on the platform or jig, pressure irons can be used locally to achieve a linear fit to prevent deformation. Direct cutting or other fire-related operations are prohibited on the sections. Heavy objects must not be piled on thin plate structures. On-site opening and plate edge trimming should be done with plasma cutting machines. Irregular parts such as arcs should be cut with templates. After the section is completed, a simulated loading of adjacent sections should be carried out. The standard for the flatness of the inner wall is 8mm (10 surfaces in total).

[0024] S2-4. Segmented welding should adopt a radial welding sequence from the center outwards and symmetrical skip welding to disperse welding heat input and reduce residual stress. When welding segmented structures, an even number of welders should weld symmetrically along the central axis of the segment. The welding sequence should follow these principles: first complete the butt welds between the frames, then weld the vertical fillet welds between the frames, and finally complete the transverse fillet welds between the frame and the plate frame. When performing vertical fillet welds, the upper weld should be completed first, and then the lower weld should be welded to suppress welding deformation.

[0025] S2-5. After the sections are removed from the tire and before welding, they must be turned over to the field. Before welding, the sections must be leveled. If they cannot be leveled, a total station must be used to check whether the sections are twisted. Welding can only be carried out after confirming that the twist is controlled within 10mm.

[0026] S2-6. After the tire is removed from the section and before the flame work, the section needs to be moved to the field and undergo a lot of back heating and flame work correction. It needs to be adjusted to a horizontal state and supported by tools such as round tubes to prevent deformation caused by the flame work.

[0027] S2-7. Requirements for support and piers after sectional tire removal: For large engine rooms, stern, bow, and transverse bulkheads, if the distance of the sectional extension to the pier is too large or the support strength of the pier is insufficient, the construction team and site supervisor must promptly report the process and construction method, and cooperate with the construction method opinions to increase support points and strengthen them to prevent deformation.

[0028] S2-8, Precision process control of the segmented bottom support structure 1 on the port side and the bottom support structure 2 on the starboard side: First, using the inner bottom as the base surface, the outer plate is inverted to form the inner bottom segment; then, the outer plate is flipped over to install the transverse bulkhead structure using the outer plate as the base surface. For example...Figures 3-4 As shown in the figure, the bow and stern reference is FR212, i.e. the 212th rib of the hull; the width reference is the centerline of the left bottom support structure bottom plate 15, and the right bottom support structure bottom plate 16 is 5250mm away from the keel; the height is measured from the FR205 (the 205th rib of the hull), the FR220 (the 220th rib of the hull), and the 3080mm baseline of the four corners; this section involves three surfaces of the membrane tank, and the local horizontal requirement is 4mm / 3m, and the overall flatness of the internal surface of the section is 8mm; S2-9, the left and right bottom corner support structures 3 and 4 are controlled in the process of section accuracy, and are built based on the membrane tank inclined plate (low-temperature steel), which is divided into three sub-sections for assembly and three side pieces for sectioning. When assembling the section, attention should be paid to the assembly sequence, and the DAP diagram should be followed, as shown in the figure; Figure 6 As shown in the figure, the bow and stern reference is FR212; the width reference is the bottom corner support structure transverse rib plate 17, which is 10290mm away from the keel; the height reference is the bottom corner support structure longitudinal rib plate 18, which is 10914mm away from the baseline; this section involves four surfaces of the membrane tank, and the local horizontal requirement is 4mm / 3m, and the overall flatness of the internal surface of the section is 8mm; S2-10, the left and right side wall support structures 5 and 6 are controlled in the process of section accuracy, and are built based on the membrane tank inner longitudinal wall 19 (low-temperature steel) on the jig, which is divided into sub-sections for assembly, and is divided into sub-sections with outer plates based on the inner longitudinal wall 20470mm away from the keel. The outer plate is used as the base surface to form the complete section of the membrane tank inner longitudinal wall 19 and the transverse bulkhead structure, which is used as the base surface to form the complete section of the membrane tank inner longitudinal wall 19 and the transverse bulkhead structure. The section is built with the outer plate as the base surface; the bow and stern reference is FR212; the width reference is the membrane tank inner longitudinal wall 19 of the side wall support structure, which is 18600mm away from the keel and is measured from the FR205 and the FR220; the height reference is the top longitudinal rib plate 20 of the side wall support structure, which is 17454mm away from the baseline; this section involves three surfaces of the membrane tank, and the local horizontal requirement is 4mm / 3m, and the overall flatness of the internal surface of the section is 8mm; The S2-11 section, the port side top corner support structure 7 and the starboard side top corner support structure 8, is constructed using the main deck as the base surface. It consists of two transverse bulkhead sections, an inner longitudinal bulkhead section 20470mm from midships, an isolation compartment floor plate section, and a membrane compartment inclined top plate 22 (low-temperature steel, fabricated on a mold) section assembly assembly. Using the inner longitudinal bulkhead 20470mm from midships as the base surface, two longitudinal ribs on the deck side plate are pre-embedded in the section assembly with outer plates. The section is constructed using the main deck as the base surface and mounted on the piers. The bow and stern reference is FR212; the width reference is the transverse rib plate 21 of the top corner support structure 12810mm from midships; the height reference is the height reference line 22800mm from the baseline on the upper wall surface of the inclined top plate 22 of the top corner support structure. This section involves four surfaces of the membrane compartment, with a local horizontal requirement of 4mm / 3m, and the standard for the overall flatness of the inner surface of the section is 8mm. The precision process control of sections S2-12, port side top support structure 9, and starboard side top support structure 10 is carried out using the main deck as the base surface. It consists of the assembly of isolated empty compartment sections and two transverse bulkhead sections. The sections are mounted on the main deck as the base surface. The construction datum for the bow and stern is FR212. The width datum is 5250mm from the center of the transverse bulkhead bottom plate 23 of the port side top support structure amidships, and the height datum is 22800mm from the baseline of the transverse bulkhead bottom plate 23 of the port side top support structure. This section involves three surfaces of the membrane compartment, with a local horizontal requirement of 4mm / 3m. The standard for the overall flatness of the inner surface of the section is 8mm. S2-13, the precision process control of the port side membrane structure section 11 is based on the bow face, and the stern bulkhead panels are fabricated on an assembly line. The section turning is based on the stern bulkhead as the base surface. The starboard side membrane structure section 12 is based on the stern face, and the bow bulkhead panels are fabricated on an assembly line. The section turning is based on the bow bulkhead as the base surface. The construction benchmark for the bow and stern is 200mm for the vertical marker of the membrane bulkhead. The width benchmark is 5250mm from the center of the port side membrane structure bow face 24 amidships. The height benchmark is 17454mm from the baseline to the top longitudinal rib 20 of the side support structure. The bow bulkhead of the port side membrane structure section 11 and the stern bulkhead of the starboard side membrane structure section 12 are membrane cabins. The local level requirement is 4mm / 3m. The standard for the overall flatness of the inner surface of the section is 8mm.

[0029] The precision control process for the assembly and loading of the membrane chamber, including assembly and loading, involves, for example... Figure 5 The three sections shown are the port side bottom section 25, the starboard side bottom section 26, and the top section 27. The port side bottom section 25 and the starboard side bottom section 26 are pre-assembled.

[0030] The left side bottom section 25 and the right side bottom section 26 are pre-joined normal section groups, the right side bottom support structure 2 is positioned based on the left side bottom support structure 1 section center line, the film cabin inner surface level is mainly controlled, and the overall level tolerance after completion is ±7mm; the longitudinal direction is a large jointing seam, the width is appropriately added with a shrinkage, and positioning welding is timely performed to avoid section movement.

[0031] The left side bottom corner support structure 3 and the right side bottom corner support structure 4 are positioned and adjusted based on the left side bottom support structure 1 and the right side bottom support structure 2 section, the film cabin inner surface level is mainly controlled, the overall level tolerance after completion is ±7mm, the film cabin half-width head-tail deviation is controlled within 4mm, and the width is appropriately added with a welding shrinkage.

[0032] The left side film structure 11 and the right side film structure 12 are positioned and joined based on the left side bottom support structure 1 and the right side bottom support structure 2 center line and horizontal line, the head-tail direction size, center line, perpendicularity and layer height are adjusted, the film cabin inner surface flatness is controlled, and positioning welding is timely performed.

[0033] The left side top support structure 9 and the right side top support structure 10 are positioned based on the right side top support structure 10 section center line, the horizontal line is adjusted in the section stage, the film cabin inner surface level is mainly controlled, the overall level after completion is ±7mm, and the width is appropriately added with a shrinkage.

[0034] The left side top corner support structure 7 and the right side top corner support structure 8 are positioned and adjusted based on the left side top support structure 9 and the right side top support structure 10 section, the film cabin inner surface level is mainly controlled, the overall level tolerance after completion is ±7mm, the half-width head-tail deviation is within 4mm, the width is appropriately added with a welding shrinkage, data measurement is performed in the film cabin, and the horizontal and width sizes are based on the section horizontal line, center line and width line.

[0035] After the section is completed, overall data measurement of the level and size must be performed, if there is an over-standard, timely rectification and confirmation are needed; the center line, horizontal line, distance from the base height line and jointing seam joint line must be re-surveyed.

[0036] The left side bottom section 25 is joined based on the ground sample center line, the level and half-width size are adjusted to be within the standard range, the dock pier and steel support are ensured to be in place and under stress, and sinking is avoided.

[0037] The right side bottom section 26 is joined based on the left side bottom section 25 section level, center line and jointing seam joint line, the width, height and perpendicularity are adjusted, and the film cabin wall flatness is ensured to be within the standard range.

[0038] The cabin top section 27 is closed with the center line, horizontal line and height from the base line as the reference, the center line, horizontal line and width are adjusted to ensure that the flatness of the film cabin wall is within the standard range.

[0039] The flatness of the inner surface of the film cabin is required to be 4 mm per 3 m, and the flatness standard of the entire inner surface is 14 mm.

Claims

1. A method for controlling the construction accuracy of a thin-film fuel tank of an LNG-powered ship, characterized by, The method comprises the following steps: S1, segmenting the main plate of the film cabin and controlling the flatness, segmenting and prefabricating the T row, assembling the main plate and other components obtained by segmenting the plate, and storing and transporting; S2, assembling the segments, completing the segment welding after the segment assembly; S3, assembling the segments according to the standard baseline, and controlling the local and overall flatness.

2. The LNG carrier membrane type fuel tank construction accuracy control method according to claim 1, characterized by, S1 specifically comprises: S1-1, after the numerical control cutting of the main plate, the stress is released by a rolling machine, the plate is stacked and transferred by using a special tray, the processed plate is placed on a flat ground, the number of stacked layers is controlled to avoid deformation caused by uneven stress, and a counterweight pressing iron is used to suppress the welding angle deformation during the plate assembly operation; S1-2, during the T row prefabrication process, the straightness of the panel and the web after cutting is checked, the T profile assembly is completed on a flat platform, the lateral bending deformation is rechecked and corrected after forming, and the qualified product flows into the segment assembly process; S1-3, the part assembly is implemented on a flat site, the positioning baffle is fixed on the side, the straightness is checked before the profile assembly, and the assembly gap is controlled; the part assembly is placed on a special bracket for storage and transportation after forming, a wooden block is added to the weak structure part to ensure flatness, and if it is not convenient to stack, an independent bracket is used for transportation; S1-4, the main plate is transported by using an electromagnetic crane, and the completed product is lifted by a bracket, and the product is lifted by a bracket according to the characteristics of the assembled parts to disperse the stress points; S1-5, the plate surface flatness meets the standard, and there is no hard bending deformation, the T profile straightness tolerance is 1m±1mm, the lateral bending deviation of the rib plate, longitudinal girder and longitudinal wall in the assembled structure is ≤4mm within the whole factory, and the resistance flatness hard file position tolerance is ≤2mm.

3. The LNG carrier membrane type fuel tank construction accuracy control method according to claim 1, characterized by, S2 comprises segment assembly, segment subsegment assembly, segment assembly, segment welding, segment transportation and segment precision process control, and specifically comprises: S2-1, the segment assembly is implemented on a special jig, the upper surface of the jig is free of welding scars, the wood block is used for leveling the suspended area of the plate, the supporting wood is added during the welding process when the welding seam is suspended from the jig or is not in the strong file position of the jig, and the thick plate is directly constrained by using the pressing iron on both sides of the welding seam to control the welding deformation; S2-2, the straightness of the parts is checked before the parts are assembled; the assembly gap of the parts is as small as possible, and a non-welding method is used; after the assembly welding is completed, the structure is annealed to release the stress generated during the welding; S2-3, segment assembly, the plate assembly is implemented on a special plate assembly jig, the segment jig uses an angle steel jig, the upper surface is free of cutting, the height of the jig is required to be ±2mm, the free plate edge of the upper plate of the jig is provided with a supporting template to ensure the flatness of the plate edge; the upper plate of the plate is ensured to be attached to the jig, the welding seam between the plates is welded by using automatic submerged arc welding, and the other side is welded and left for automatic submerged arc welding after the segment is turned over; in order to reduce the welding deformation, the "7" shaped clamping plate or the non-welding method is used for fixation. S2-4, the welding sequence is adopted by self-centering and radially welding and symmetrically skip welding; when welding the segmented structure, double welders are adopted, symmetrically welding along the middle axis of the segmented structure, first completing the butt welding seam between the frames, then welding the vertical fillet welding seam between the frames, and finally completing the horizontal fillet welding seam between the frame and the plate frame; When welding the vertical fillet, the upper weld is completed first, and then the lower weld is welded; S2-5, after the segmented structure is lowered, the segmented structure is turned over to the outside field before welding, the segmented structure is adjusted horizontally before welding, if it cannot be leveled, the total station instrument is used to confirm whether the segmented structure is twisted, and the welding operation is performed when the twisted degree is controlled within 10 mm; S2-6, after the segmented structure is lowered, the segmented structure needs to be translated to the outside field before the fire correction, a large amount of back heating and fire correction is required, the segmented structure is adjusted to the horizontal state and supported by the tool, and the deformation caused by the fire is prevented; S2-7, after the segmented structure is lowered, the support and the riding pier are used for the large machine cabin tail, head and transverse bulkhead segmented structure, the distance of the segmented structure extending out of the riding pier is too large or the support strength of the riding pier is insufficient, the process method is fed back in time, the support points are increased and strengthened according to the method, and the deformation is prevented.

4. The LNG carrier membrane type fuel tank construction accuracy control method according to claim 1, characterized by, In S3, the total segment is pre-assembled, the overall level is controlled within ±7mm based on the center line, horizontal line and distance from the fitting line, and the half-width deviation is less than or equal to 4mm.

5. The LNG carrier membrane type fuel tank construction accuracy control method according to claim 1, characterized by, In S3, the local flatness of the inner surface of the membrane cabin is required to be 4mm / 3m, and the whole surface flatness standard is 8mm in the segmented stage or 14mm in the total segment stage.

6. The LNG powered ship thin film type fuel tank construction accuracy control method according to claim 3, characterized by, The segments include: a left side bottom support structure (1), a right side bottom support structure (2), a left side bottom corner support structure (3), a right side bottom corner support structure (4), a left side wall support structure (5), a right side wall support structure (6), a left side top corner support structure (7), a right side top corner support structure (8), a left side top support structure (9), a right side top support structure (10), a left side membrane structure (11), and a right side membrane structure (12).

7. The LNG powered ship thin film type fuel tank construction accuracy control method according to claim 6, characterized in that: The segmented precision process control of the left side bottom support structure (1) and the right side bottom support structure (2) is performed by first forming the inner bottom segment by inversely buckling the plate body based on the inner bottom, and then turning over the plate to install the transverse bulkhead structure based on the plate; The segmented precision process control of the left side bottom corner support structure (3) and the right side bottom corner support structure (4) is performed by building based on the membrane cabin inclined plate, and three sub-segment assemblies and three side plate segments are formed; The segmented precision process control of the left side wall support structure (5) and the right side wall support structure (6) is performed by making sub-segment assemblies based on the inner longitudinal wall (19) of the membrane cabin, making sub-segment assemblies based on the inner longitudinal wall within the distance of 20470mm from the keel, and then turning over the plate to form the complete segment by installing the inner longitudinal wall (19) of the membrane cabin and the transverse bulkhead structure based on the plate; The segmented precision process control of the left side top corner support structure (7) and the right side top corner support structure (8) is performed by inversely building based on the main deck, and the components are composed of two transverse bulkhead sub-segment assemblies, the inner longitudinal wall sub-segment assembly within the distance of 20470mm from the keel, the isolation cabin bottom plate sub-segment assembly, and the membrane cabin inclined top plate (22) sub-segment assembly. The left side top support structure (9) and the right side top support structure (10) are controlled in a segmented precision process, are reversely manufactured based on a main deck, are assembled by an isolated air cabin subsegment and two transverse cabin wall subsegments, and are reversely manufactured based on a tail end wall. The left side thin film structure (11) is manufactured based on a bow end surface, tail end wall wallboards are manufactured on a flow line, and the left side thin film structure (11) is reversely manufactured based on the tail end wall as a base surface. The right side thin film structure (12) is manufactured based on a tail end surface, bow end wall wallboards are manufactured on a flow line, and the right side thin film structure (12) is reversely manufactured based on the bow end wall as a base surface.

8. The LNG powered ship thin film type fuel tank construction accuracy control method according to claim 7, characterized by: S3 includes three total segments of a left side cabin bottom total segment (25), a right side cabin bottom total segment (26) and a cabin top total segment (27), and the left side cabin bottom total segment (25) and the right side cabin bottom total segment (26) are pre-joined and total assembled; The left side cabin bottom total segment (25) and the right side cabin bottom total segment (26) are pre-joined and total assembled, the right side bottom support structure (2) is positioned based on the segmented center line of the left side bottom support structure (1) as a reference, the left side bottom corner support structure (3) and the right side bottom corner support structure (4) are total assembled and positioned based on the segmented left side bottom support structure (1) and the segmented right side bottom support structure (2) as a reference, The left side thin film structure (11) and the right side thin film structure (12) are total assembled and joined based on the center line and the horizontal line of the left side bottom support structure (1) and the right side bottom support structure (2) as a reference, The left side top corner support structure (7) and the right side top corner support structure (8) are total assembled and positioned based on the segmented left side top support structure (9) and the segmented right side top support structure (10) as a reference, The left side cabin bottom total segment (25) is joined based on the center line of a ground sample, the right side cabin bottom total segment (26) is joined based on the total segment horizontal line, the center line and the joining seam line of the left side cabin bottom total segment (25) as a reference, and the cabin top total segment (27) is joined based on the center line, the horizontal line and the distance from the base line as a reference. ​ ​

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