Construction method of large water jet propulsion flow channel of ship

Abstract

The invention discloses a construction method of a large water jet propulsion flow channel of a ship, belongs to the technical field of ship production, and solves the technical problem of poor production precision of an existing water jet propulsion flow channel construction method. The method comprises the following steps that 1, construction preparation and benchmark establishment are conducted, specifically, the construction preparation comprises drawing digestion, a construction process is compiled according to a drawing, and necessary tools are designed; the reference establishment specifically comprises the following steps: after ship body sections are closed, a ship body base line, a ship body center line and a shaft system theoretical center line are clearly calibrated again in a mounting area to serve as absolute references of all subsequent mounting work; 2, determining the technological requirements for manufacturing important parts and related structures of the runner; 3, the runner is manufactured in a segmented mode, and all the segments of the runner are spliced according to the technical requirements of the technology; and step 4, folding and positioning the slipway, rechecking the axis of the runner, and adjusting to meet the process requirements. The ultrahigh coaxiality of the propelling channel is ensured, and meanwhile, the extreme fairness and the structural integrity of the flow channel are ensured.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and more specifically, to a construction method for a large waterjet propulsion channel for ships. Background Technology

[0002] With the development of modern ships towards higher speeds and greater intelligence, waterjet propulsion systems are widely used due to their high efficiency, low noise, and excellent maneuverability. The inlet channel, as a key component of the waterjet propulsion system, has a complex structure and requires extremely high installation precision. Traditional channel construction relies heavily on experience and lacks systematic process guidance. In practical applications, problems such as uneven joints between channel plates and unstable weld quality often occur, affecting the overall propulsion performance.

[0003] While existing technologies have proposed some improvements, most focus on optimizing single processes and fail to address the overall challenge of controlling cumulative dimensional errors throughout the entire process from segmented manufacturing to final assembly. Furthermore, there are still significant shortcomings in effectively ensuring the smoothness of the internal flow channel profile and reducing welding deformation.

[0004] Therefore, there is an urgent need to develop a scientific, reasonable, and highly replicable integrated construction scheme to improve the overall construction level of large-scale water jet propulsion channels. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art. The purpose of the present invention is to provide a scientific, reasonable and highly reproducible construction method for large-scale waterjet propulsion channels for ships.

[0006] The technical solution of this invention is: a construction method for a large waterjet propulsion channel for ships, comprising the following steps: Step 1. Construction preparation and benchmark establishment. Construction preparation includes understanding the drawings, developing construction technology based on the drawings, and designing necessary tooling. Benchmark establishment specifically involves: after the hull sections are assembled, clearly marking the hull baseline, hull centerline, and theoretical shaft centerline in the installation area as the absolute benchmark for all subsequent installation work. Step 2. Determine the technological requirements for the fabrication of each important component and related structure of the flow channel; Step 3. The flow channel is manufactured in sections, and the sections are spliced ​​together according to the process requirements; Step 4. Close and position the ship on the slipway, check the flow channel axis and adjust it to meet the process requirements.

[0007] As a further improvement, in step 1, the drawing digestion specifically involves: thoroughly analyzing the flow channel structure diagram, shaft system layout diagram, base structure diagram, and related welding process documents to fully understand the installation tolerances of each accessory of the entire shaft system; The specific construction process is as follows: From aspects of process design, blanking and processing, small assembly construction, sectional assembly construction, large assembly construction, and hull shafting construction, detailed "Construction Process for Runner Fabrication and Installation" and "Construction Process for Hull Shafting" are formulated, clarifying the process design, precision control standards, welding sequence, and inspection methods for each step; Necessary tooling includes support frames, positioning cleats, and template wood patterns.

[0008] Furthermore, step 2 includes: Determine the process requirements for fabricating the tail flange; Determine the process requirements for fabricating the stiffening ring; Determine the process requirements for fabricating the cylindrical body; Determine the process control requirements for fabricating the tail seal plate; Determine the process control requirements for fabricating the trumpet-shaped mouth at the tail end of the runner; Determine the shafting protection pipe; Determine the side seal plate of the anti-harmonic piece; Determine the hull rib frame in the runner area.

[0009] Furthermore, the process requirements for fabricating the tail flange are as follows: The tail flange is blanked from a 40-mm thick plate, assembled into a ring by small assembly segments and welded to the tail seal plate, and the轮机专业现场按相关要求进行加工和钻孔; The inner and outer side grooves of the tail flange are machined mechanically, and the inner and outer circular inner-cut grooves are machined. (It seems there is an incorrect expression here. Maybe it should be something like "processed and drilled by the轮机专业现场 according to relevant requirements")

[0010] Furthermore, the process requirements for fabricating the stiffening ring are as follows: When splicing the stiffening ring, the roundness and dimensions of the inner circular hole are controlled by a "cross-shaped" stiffening frame.

[0011] Furthermore, the process control requirements for fabricating the tail seal plate are as follows: For the entire area of the four pump openings on the tail seal plate, a single whole plate is used for blanking. During the blanking stage, numerical control hole opening is performed to ensure the overall flatness of the tail seal plate and the cutting accuracy of the circular holes; When splicing the plates, the center line and cross line of the tail seal plate are marked based on the centers of the four circular holes on the non-structural surface to ensure correct splicing of the tail seal plate. Strengthening is done before welding, and the reverse center line and the structural installation line are marked on the structural surface to ensure the overall flatness on the non-structural surface side of the four circular holes.

[0012] Furthermore, the process control requirements for fabricating the trumpet-shaped mouth at the tail end of the runner are as follows: The transition plate connecting the trumpet-shaped mouth at the tail end of the runner to the "shrimp section" of the runner is blanked from a 32-mm thick plate. After blanking and processing, the groove is刨好 (it seems there is an incorrect expression here. Maybe it should be something like "prepared properly") according to requirements and the inner diameter allowance is finely machined into a cylinder, and then provided to machining for boring the inner hole and turning the outer edge. The processed cone meets the inner diameter design requirements.

[0013] Furthermore, to ensure the linear accuracy of the runner, the outer plate of the runner is processed by a runner model processing sample box.

[0014] Furthermore, step 3 includes: Develop the installation procedure for the stern section structure; Develop the installation procedure for the water inlet channel; Develop the positioning and installation procedures and process requirements for the "shrimp joint" structure of the flow channel.

[0015] Furthermore, step 4 includes: Center line of the slipway is depicted; Positioning of the forward engine room section on the slipway; The aft engine room section was hoisted onto the slipway. The stern section was joined and positioned on the slipway, and the flow channel axis was checked and adjusted. A 6mm downward counter-deformation is applied to the end point of the main section; Once the conditions for the construction of the engine shafting are met, all major equipment on the ship will be in place or simulated ballasting, ship condition measurement and adjustment will be carried out. Recheck and adjust the axis of the main unit base, gearbox base, and flow channel cylinder pull wire; Confirmation of shaft system reference points and axis.

[0016] Beneficial effects Compared with the prior art, the advantages of this invention are as follows: This invention innovatively constructs a three-in-one benchmark coordination system for the hull, shafting, and flow channel. By independently establishing a self-datum for the flow channel during the segmented manufacturing stage and precisely aligning it with the shafting precision datum (corrected for sag) during the slipway assembly stage, ultra-high coaxiality of the propulsion channel is ensured. Simultaneously, a template-driven structured active assembly strategy and a closed-loop deformation control covering the entire process of "pre-strengthening - precision welding - dynamic adjustment" guarantee the ultimate smoothness and structural integrity of the flow channel. This method systematically solves the core challenges of constructing large and complex flow channels, significantly improving ship performance and construction quality, and has significant application value. Attached Figure Description

[0017] Figure 1 This is a flowchart of the present invention; Figure 2 This is a structural diagram of the flow channel; Figure 3 for Figure 2 Magnification at point B; Figure 4 for Figure 2 Structural diagram in direction A; Figure 5 Welding requirements for the tail flange; Figure 6 The beveling requirements for the tail flange; Figure 7 To strengthen the requirements for process control in the ring manufacturing process; Figure 8It is a "rice-shaped" strengthening structure; Figure 9 It is a tail seal plate strengthening structure; Figure 10 It is a shafting guy bracket structure; Figure 11 It is a rib frame channel steel strengthening structure; Figure 12 It is the installation sequence of the runner plate; Figure 13 It is the installation sequence of the "shrimp segment" structure; Figure 14 It is the cutting sequence of the tail seal plate runner opening; Figure 15 It is the connection node of the runner structure; Figure 16 It is the node control of the runner structure; Figure 17 It is a sample card schematic diagram; Figure 18 It is a schematic diagram for calculating the sag of the wire rope. Specific implementation mode

[0018] The following further describes the present invention in conjunction with specific embodiments in the drawings.

[0019] Refer to Figures 1 to 18 , a construction method for a large water jet propulsion runner of a ship, including the following steps: Step 1. Construction preparation and datum establishment. The construction preparation includes drawing digestion, preparing a construction process according to the drawings, and designing necessary tooling; the datum establishment is specifically: after the hull section is closed, the hull baseline, hull center line and shafting theoretical center line are clearly re-marked in the installation area as the absolute datum for all subsequent installation work; Step 2. Determine the process technical requirements for manufacturing each important component and related structure of the runner; Step 3. Fabricate the runner in sections and splice each section of the runner according to the process technical requirements; Step 4. Shipyard closing and positioning, recheck the runner axis and adjust it to meet the process requirements.

[0020] In Step 1, the construction preparation is as follows: (1) Drawing digestion: Deeply analyze the runner structure drawing, shafting layout drawing, pedestal structure drawing and related welding process documents, and fully understand the installation tolerances of each accessory of the entire shafting. For example, the main engine and gearbox use epoxy resin gaskets with a relatively large gasket thickness range, that is, the pedestal height can be appropriately adjusted, providing favorable conditions for the construction of the pump jet runner in the sectional stage.

[0021] (2) Process planning: Develop detailed "Construction Process for the Fabrication and Installation of the Flow Channel" and "Construction Process for the Hull Shafting" from aspects such as process design, blanking and processing, small assembly construction, sectional assembly construction, large assembly construction, and hull shafting construction, and clarify the process design (main seam layout, allowance release, and reverse deformation amount, etc.), accuracy control standards, welding sequence, and inspection methods for each step.

[0022] (3) Tooling design: Prepare necessary tooling such as support frames, positioning cleats, and template wood patterns.

[0023] In Step 2, taking the 60-meter-class high-speed patrol boat as an example, as Figures 2-4 shown, the process technical requirements include: (1) Determine the process requirements for the fabrication of the tail flange (base ring) The tail flange connected to the water jet propulsion device on the tail seal plate is cut from a 40-mm (DH36) thick plate (cut into a semi-ring with an inner diameter of 1096 mm and an outer diameter of 1270 mm and spliced together), and is assembled into a ring and welded on the tail seal plate in the small assembly stage (note that the splicing weld is in the horizontal direction). The轮机专业现场按相关要求进行加工和钻孔(厚度加放5mm余量,内径单边加放3mm余量)。尾部法兰若太大,采用双半圆拼接的,应控制内圆孔尺寸及法兰圆圈整体平面度,拼接的焊缝应磨平。尾部法兰内外侧坡口应采用机械加工,法兰内外圆内切坡口加工,如 Figures 5-6 shown, using a cutting torch or carbon arc gouging to open the groove is likely to cause deformation of the unmounted flange and is not suitable for using a cutting torch or carbon arc gouging to open the groove.

[0024] (2) Determine the process requirements for the fabrication of the stiffening ring When splicing the stiffening ring (φ1270), the roundness and size of the inner circular hole are controlled by a "cross-shaped" stiffening frame, as Figures 7-8 shown, and the fillet weld size of the flange panel corner joint is controlled to prevent blocking or hitting the installation of subsequent equipment screws.

[0025] (3) Determine the process requirements for the fabrication of the cylindrical body The 12-mm tapered transition plate connected to the tail seal plate does not need to be processed into an 8- to 12-mm tapered plate because it does not interfere with the water flow in the flow channel. It can be processed into a cylinder with an inner diameter of 1102 mm using only a 12-mm (DH36) thick plate. The machining accuracy of the inner diameter needs to be ensured during the blanking and processing stage, and it should be the same as the opening size on the tail seal plate after processing; the roundness and size of the inner circular hole should be controlled during the splicing of the φ1102 cylindrical body.

[0026] (4) Determine the process control requirements for the fabrication of the tail seal plate The four nozzle holes on the tail seal plate are cut from a single sheet. During the cutting stage, CNC drilling is performed (with a 5mm allowance for the round holes, i.e., boring allowance) to ensure the overall flatness of the tail seal plate and the cutting accuracy of the round holes. When assembling the plates, the center line and crosshairs of the tail seal plate are marked using the centers of the four round holes on the non-structural surfaces to ensure correct assembly. Reinforcement is performed before welding, as follows. Figure 9 As shown, the reverse center line and structural installation line are engraved on the structural surface (if there is a rolling mill, the tail sealing plate can be welded and then reinforced after rolling), ensuring the overall flatness of the non-structural side of the four round holes; install the structure, weld, grind, and use fire to relieve stress (do not disassemble the reinforcement first), and then proceed to the segmented installation stage.

[0027] (5) Determine the process control requirements for the fabrication of the flared end of the flow channel. The transition plate connecting the flared end of the flow channel to the "shrimp joint" part of the flow channel is made of 32mm (DH36) thick plate. During the blanking and processing stage, the bevel is cut as required and the cylinder is precision machined with an inner diameter of 792mm (the weld is treated after welding). It is then provided to the machining center for boring the inner hole and machining the outer edge. The processed cone meets the dimensional requirements of an inner diameter of 800mm and an outer diameter of 816~856mm.

[0028] (6) Process control requirements for the fabrication of the outer plate of the flow channel To ensure the accuracy of the flow channel line, the 8mm flow channel outer plate is processed by a flow channel model machining template box (i.e., a 1:1 model of the flow channel is made first, and the model is used as a reference for processing).

[0029] (7) Process control requirements for shaft protection pipes The shaft protection pipe was selected, taking into account corrosion prevention and painting operations. The shaft protection pipe passing through the flow channel was made of galvanized seamless steel pipe with a specification of φ194X10 (material: 20#). The shaft protection pipe passed through the "shrimp joint" of the flow channel and extended into the cylindrical body.

[0030] (8) Process control requirements for the anti-resonance plate side sealing plate The anti-resonance plate side sealing plate is determined according to the drawings, and then the sample box of the anti-resonance plate side sealing plate model is processed.

[0031] (9) Process control requirements for the hull rib frame in the flow channel area Based on the drawings, determine the hull rib frame for the flow channel area. First, draw the lines on the platform, and then assemble the frame according to the rib frame lines to ensure accuracy.

[0032] In step 3, the flow channel sections are machined according to the drawings and process requirements (process requirements in step 2). Key precision control points include: the correct installation of the stern sealing plate and related flow channel structures; the concentricity control of the stern flange, stern sealing pump opening, φ1102 cylindrical body, φ800 cylindrical body, stern shaft tube, etc.; and the control of connection nodes. Additionally, the shafting guide frames (with the guide reference marked with punch points) fabricated for each section should not be removed; they should be retained for dock positioning and verification. Figures 2-4 As shown.

[0033] The splicing of the various segments of the flow channel includes the following procedures: 1. Develop the installation procedure for the stern section structure. 1.1 Position and hoist the stern compartment tail seal plate, ribs, and bulkhead.

[0034] 1.2 At the center of the main hull section and the center line of the left and right water inlets, respectively, guy wire frames are installed at the bow and stern ends.

[0035] 1.3 Erect a measurement marker on the center guy wire of the main hull section; simultaneously erect measurement markers for the horizontal height of the inner center point of the rib flow channel on the left and right guy wires, as follows. Figure 10 As shown.

[0036] 1.4 Based on the measurement values ​​marked on the template, adjust the distance from the center point of the inner circle of the rib to the center of the hull section, and at the same time adjust the distance from the horizontal height of the center point of the inner circle to the baseline of the hull section.

[0037] 1.5 Install rib frame channel steel reinforcement, as follows: Figure 11 As shown, this is to prevent deformation during the welding of the rib frame.

[0038] 1.6 Install the longitudinal structure of the stern compartment tail seal plate, and perform overall structure installation, grinding, and inspection.

[0039] 1.7 Perform welding of the stern compartment stern sealing plate side structure, and install and weld the outer plate.

[0040] 2. Develop an installation procedure for the water inlet channel. 2.1 First install the flow channel plate with an arc angle, then install the straight flow channel plate, such as... Figure 12 As shown, the line shape is larger initially, then smaller.

[0041] 2.2 Grind off the oxide scale at the location of the flow channel plate installation structure line (approximately 20 mm from both sides of the joint).

[0042] 2.3 Install on the inner upper edge of the flow channel (with a horizontal arc shape) → Install on the outer upper edge → Cut and grind the excess material.

[0043] 2.4 Installation of the bottom plate of the flow channel → Installation of the top plate → Cutting and grinding of the allowance.

[0044] 2.5 Inner side plate installation for flow channel → Outer side plate installation → Cutting and grinding of excess material.

[0045] 2.6 Installation of the center base plate of the flow channel → Cutting and grinding of the allowance.

[0046] 2.7 The inner and outer ribs of the flow channel are engraved with round steel arcs using a sample plate → cut and grind.

[0047] 2.8 Install the linear round steel bar for the flow channel lip, and cut and grind the excess material around the plate seam where the round steel bar is located.

[0048] 2.9 Tail bottom rotating plate installation → excess material cutting and grinding.

[0049] 2.10 Positioning and installation of the "shrimp section" (bending section of the flow channel) → Cutting and grinding of the remaining material.

[0050] 2.11 After the overall installation of the flow channel, beveling is prepared → grinding and cleaning → assembly and inspection.

[0051] 2.12 Flow channel plate welding → grinding and cleaning → welding inspection.

[0052] 3. Develop the installation procedure and process requirements for the "shrimp joint" structure of the flow channel. 3.1 Installation Program like Figure 13 As shown, the process is as follows: Installer 5 → Installer 4 → Installer 3 → Install longitudinal reinforcing ribs and reinforcing rings → Assembly inspection → Install cross-shaped reinforcement → Welding → Installer 2 → Installer 0 → Assembly inspection → Install cross-shaped reinforcement → Welding → Installer 1 → Welding → Tail shaft tube installation → Install anti-resonance plate → Assembly inspection → Install reinforcement → Welding → Grinding and repair welding → Completion measurement and inspection → Install tail flange and reinforcing ring → Assembly inspection → Welding → Inspection → Proceed to the next process.

[0053] 3.2 Process Requirements 3.2.1 Before installation, all structures must be beveled according to the welding process requirements, and three sides must be ground and the paint removed.

[0054] 3.2.2 When installing parts 3, 4, and 5, ensure that the center structural line of the "shrimp joint" plate of the flow channel is aligned with the upper longitudinal structure of the flow channel, and that the plate seams face the center of the ship. When installing part 0, its tolerance is ±2mm, and the end face must be perpendicular to the baseline.

[0055] 3.2.3 When installing the flow channel "shrimp joint", minimize the number of feet. Spot welding should be done on the inside of the flow channel so that the outside can be welded to the inside for carbon gouging and root cleaning.

[0056] 3.2.4 To reduce the impact of welding deformation on the installation accuracy of part 2, after part 3 is installed, parts 3, 4, 5 and their components can be inspected and welded first. Part 2 requires to be processed as a whole in the processing workshop. When the material arrives, it must be inspected and qualified according to the sample before it can be installed. Its installation accuracy must be strictly controlled.

[0057] 3.2.5 After installing part 1, the tail seal plate flow channel opening can be cut with an allowance of R545, leaving 3mm on each side for the turbine's professional boring. To reduce heat deformation during cutting, the following method should be used: First, cut grooves 1-8 to divide the circle into eight equal parts, then divide symmetrically, and so on, dividing 1-4 in sequence, as follows. Figure 14 As shown (symmetrical from left to right).

[0058] 3.2.6 The tail shaft tube installation must be carried out after the flow channel “shrimp section” is welded and inspected. During installation, it should extend 30mm outwards to the tail to allow for the boring by the turbine specialist. An additional 2mm of anti-deformation should be added downwards at the stern.

[0059] 3.2.7 The handhole opening shall be made according to the actual object, and must have the same curvature as the flow channel, and there shall be no water-blocking steps.

[0060] 3.2.8 The stern flange must be machined. The flange is annular, 40mm thick, with an inner diameter of 1096mm and an outer diameter of 1270mm. During machining, a 3mm machining allowance should be added to each side of the inner diameter. The bevel between the flange and the stern sealing plate must be properly made. When installing the stern flange, the verticality and flatness of the stern sealing plate must be checked. To reduce welding deformation, welding should be carried out strictly according to the welding process requirements, and appropriate reinforcement should be added.

[0061] 3.2.9 The flange and tail shaft tube must be concentric. If there is any deviation, it is best to have the deviation in the same direction.

[0062] 3.2.10 Tolerances: Out-of-roundness ±3mm, concentricity ±2mm.

[0063] 3.3 Key Components and Control Points for Flow Channel Structure Installation 3.3.1 Pay attention to the connection nodes and accuracy requirements of important components in the flow channel structure, such as... Figure 15 , Figure 16 As shown.

[0064] 3.3.2 Installation dimensions and roundness of part 3: During installation, the axis must be properly aligned to ensure R=400mm, and gauge A (see...) should be used. Figure 17 Check the roundness. The remaining amount will be cut according to the positioning dimensions of part 2 after welding is completed and part 2 is installed, taking into account the sag.

[0065] 3.3.3 Installation dimensions and roundness of part 2: Upon arrival, the material must be inspected using sample A. Only after passing the inspection can the next process be carried out. The distance from the end cap plate is 420mm, with a tolerance of ≤5mm. A spirit level must be used to ensure that it is installed horizontally, and the amount of sag must be taken into account.

[0066] 3.3.4 Tail flange installation and welding deformation control: Before installation, use sample B to check the flatness and verticality of the tail sealing plate. The tolerance is ≤3mm. Installation is only allowed after the inspection is qualified. Welding should be carried out symmetrically in strict accordance with the welding process requirements. Reinforcement measures should be taken before welding.

[0067] 3.3.5 Installation of anti-resonance elements: The installation angle must be strictly controlled, and the angle sample must be provided by the installation drawings. The welding must be carried out in strict accordance with the welding process requirements.

[0068] 3.3.5 Before the tail section is removed from the mold, stress relief is carried out by fire, weld flaw detection and tightness test are performed, and final measurement and inspection are conducted.

[0069] The construction process in step 4 includes: 4.1 Centerline marking on the slipway, including the centerline of the stern section flow channel, the stern geodetic line marking of the shafting, and the stern reference point marking of the shafting; 4.2 Position the fore-engine section on the slipway and recheck the base axis and adjustments, specifically ensuring that the main engine base and gearbox base are level and centered as required, determine the hull baseline, confirm the main process, and ensure that the slipway piers for this section are strictly compacted and tamped as required. 4.3 The aft engine room section is hoisted on the slipway. Based on the fore engine room section, the sections are joined and positioned, and the base axis is checked and adjusted. Specifically, the main engine base and gearbox base are level and centered, etc., and the chief process manager confirms that the slipway piers of this section are strictly tightened and compacted as required. 4.4 The stern section is assembled and positioned on the slipway, and the flow channel axis (the guy wire frame set up for the flow channel fabrication of the stern section) and adjustments are checked. Specifically, the verticality of the stern flange, the center of the inner diameter of the cylinder at the stern end of the flow channel (the cylinder with an inner diameter of 1102mm that connects to the stern seal, the cylinder with an inner diameter of 800mm that connects the flared mouth of the flow channel to the "shrimp joint" part of the flow channel, and the base ring with an inner diameter of 1096mm that connects to the water jet propulsion device on the stern seal plate), and the center of the front and rear inner diameters of the stern shaft tube meet the requirements, and the main process is confirmed. 4.5 Apply a 6mm downward counter-deformation to the stern end of the main section, and add 3 tons of weight on each side of the stern main deck surface to prevent the stern from warping too much when the hull is joined and welded. The piers on this section of the slipway must be tightened and compacted strictly as required. 4.6 Once the conditions for the construction of the engine shafting are met, all major equipment on the ship shall be in place or simulated ballasting, ship condition measurement and adjustment shall be carried out. 4.7 Check and adjust the axis of the main unit base, gearbox base, and flow channel cylinder by pulling the guide wire. Prioritize ensuring the accuracy of the pump installation parts such as the flow channel cylinder. Epoxy resin gaskets are used for the main unit and gearbox. The gasket thickness has a wide range and can be adjusted appropriately. When pulling the guide wire, consider the sag of the steel wire at the corresponding position and correct it during measurement or installation. The formula for calculating the sag is as follows:

[0070] In the formula, Let represent the sag of the steel wire at point A (mm). This refers to the weight of the steel wire per meter (g / m). The distance (m) between the two reference points of the steel wire. The force required to tighten the steel wire is approximately equal to 75% (kg) of the wire's tensile strength. Where A is the distance from the reference point (m), and 0.99 is a correction factor. Figure 18 As shown.

[0071] 4.8 Confirmation of shafting reference points and axis, installation of intermediate bearing housing, installation confirmation, welding and grinding → compilation of hull shafting completion data, measurement and inspection → delivery to marine engineering professionals for construction.

[0072] The advantages of this invention are mainly reflected in the following aspects: "Three-in-one" benchmark coordination system: Innovation: It proposes a three-in-one datum coordination concept of "hull-shaft-flow channel". Instead of simply relying on the main hull datum, it innovatively establishes an independent "flow channel self-datum" for the flow channel during the section manufacturing stage, and aligns this self-datum with the "shaft precision datum" that has been accurately corrected for sag during the dock assembly stage.

[0073] Function: This collaborative approach effectively isolates the accumulated errors during the hull construction process, ensuring ultra-high coaxiality of the propulsion channel (from the shaft system to the flow channel), which is difficult to achieve with traditional methods.

[0074] Template-driven structured active assembly strategy: Innovation: Dedicated inspection templates (such as template A and template B) are used to drive and guide the entire assembly process. The assembly sequence follows strict logic (e.g., assembling complex plates with rounded corners first, followed by straight plates), making it an "active" rather than "passive" assembly method.

[0075] Function: It transforms abstract precision requirements into intuitive and operable tooling, ensuring the ultimate smoothness of the inner surface of the flow channel and significantly reducing reliance on the worker's personal experience.

[0076] Full-process deformation closed-loop control: Innovation: A closed-loop control system for welding deformation control covering the entire process from "pre-strengthening to precision welding to dynamic adjustment" was proposed. This includes "rice"-shaped reinforcement before welding, symmetrical welding sequence, post-weld heat treatment, and pre-setting of anti-deformation amount (e.g., adding 2mm downwards) during the installation of key nodes (such as tail shaft tubes and flanges).

[0077] Function: To control deformation throughout the entire manufacturing process, preventing and managing deformation at its source, rather than trying to remedy problems after they occur.

[0078] Dynamic closed-loop adjustment mechanism: Innovation: Key components (such as the stern flange) retain machining allowances during initial installation. Their final precise positioning and cutting are carried out based on multi-point measured data after the shafting-related equipment (main engine, gearbox) is positioned on the actual ship and the final measurement is completed.

[0079] Function: It realizes "dynamic closed-loop adjustment" to ensure that the flow channel and the subsequently installed spray pump equipment achieve optimal matching.

[0080] Scientific correction of sagging: Innovation: A calculation formula for the sag of the precision reference steel wire in the shaft system is clearly given, providing a theoretical basis for accurate reference correction.

[0081] Function: It ensures the scientific nature and accuracy of the string line reference and is the foundation for achieving high-precision alignment.

[0082] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A construction method for a large waterjet propulsion channel for ships, characterized in that, It includes the following steps: Step 1. Construction preparation and datum establishment. The construction preparation includes drawing digestion, formulating construction technology according to the drawings, and designing necessary tooling. The datum establishment specifically means: after the hull sections are joined together, clearly re-mark the hull baseline, hull centerline, and theoretical centerline of the shafting in the installation area as the absolute datum for all subsequent installation work; Step 2. Determine the technological requirements for the production of each important component and related structure of the flow passage; Step 3. Fabricate the flow passage in sections and splice each section of the flow passage according to the technological requirements; Step 4. Position and join the components on the shipbuilding berth, recheck the axis of the flow passage and adjust it to meet the technological requirements.

2. The construction method of a large waterjet propulsion channel for ships according to claim 1, characterized in that, In Step 1, the drawing digestion specifically means: deeply analyze the flow passage structure drawing, shafting layout drawing, pedestal structure drawing, and related welding process documents to fully understand the installation tolerances of each accessory of the entire shafting; Formulating the construction technology specifically means: formulate detailed "Construction Technology for Fabrication and Installation of Flow Passage" and "Construction Technology for Hull Shafting" from aspects of process design, blanking and processing, small assembly construction, sectional assembly construction, large assembly construction, and hull shafting construction, and clarify the process design, precision control standards, welding sequence, and inspection methods for each step; The necessary tooling includes support frames, positioning horse plates, and template wood samples.

3. The construction method of a large waterjet propulsion channel for ships according to claim 1, characterized in that, In Step 2, it includes: Determine the technological requirements for the production of the tail flange; Determine the technological requirements for the production of the stiffening ring; Determine the technological requirements for the production of the cylinder body; Determine the process control requirements for the production of the tail seal plate; Determine the process control requirements for the production of the bell mouth at the tail end of the flow passage; Determine the shafting protection pipe; Determine the side seal plate of the anti-harmonic piece; Determine the hull rib frame in the flow passage area.

4. The construction method of a large waterjet propulsion channel for ships according to claim 3, characterized in that, The technological requirements for the production of the tail flange are: the tail flange is blanked from a 40-mm-thick plate, assembled into a ring by small assembly sections and welded to the tail seal plate, and the轮机 professional (it should be noted that this "轮机专业" might need to be accurately translated according to the actual professional name in the context) processes and drills holes on-site according to relevant requirements; the inner and outer side grooves of the tail flange are machined mechanically, and the inner and outer circular inner-cut grooves are processed.

5. The construction method of a large waterjet propulsion channel for ships according to claim 3, characterized in that, The technological requirements for the production of the stiffening ring are: when splicing the stiffening ring, use a "cross" - shaped reinforcing frame to control the roundness and size of the inner circular hole.

6. The construction method of a large waterjet propulsion channel for ships according to claim 3, characterized in that, The process control requirements for the production of the tail seal plate are: for the entire area of the four spray pump openings on the tail seal plate, use a single whole plate for blanking, and perform numerical control hole opening during the blanking stage to ensure the overall flatness of the tail seal plate and the cutting accuracy of the circular holes; when splicing the plates, draw the center line and cross line of the tail seal plate from the centers of the four circular holes on the non-structural surface to ensure the correct splicing of the tail seal plate. Strengthen it before welding, and mark the structure installation line on the reverse center line and the structural surface to ensure the overall flatness of the non-structural surface side of the four circular holes.

7. The construction method of a large waterjet propulsion channel for ships according to claim 3, characterized in that, The process control requirements for the production of the bell mouth at the tail end of the flow passage are: the transition plate connecting the bell mouth at the tail end of the flow passage to the "shrimp section" of the flow passage is blanked from a 32-mm-thick plate. After blanking and processing, bevel the groove according to the requirements and finish machining it into a cylinder according to the inner diameter allowance, and then provide it to the machining for boring the inner hole and turning the outer edge. The processed cone meets the inner diameter design requirements.

8. The construction method of a large waterjet propulsion channel for ships according to claim 3, characterized in that, To ensure the linear accuracy of the flow passage, the outer plate of the flow passage is processed by the flow passage model processing sample box.

9. The construction method of a large waterjet propulsion channel for ships according to claim 1, characterized in that, In Step 3, it includes: Formulate the installation procedure for the stern general section structure; Formulate the installation procedure for the inlet flow passage; Formulate the positioning installation procedure and technological requirements for the "shrimp section" structure of the flow passage.

10. A construction method for a large waterjet propulsion channel for ships according to claim 1, characterized in that, In Step 4, it includes: 刻画船台中心线 (it should be noted that "刻画" might need to be accurately translated according to the context, for example, "mark the center line of the shipbuilding berth") Positioning of the forward engine room section on the slipway; The aft engine room section was hoisted onto the slipway. The stern section was joined and positioned on the slipway, and the flow channel axis was checked and adjusted. A 6mm downward counter-deformation is applied to the end point of the main section; Once the conditions for the construction of the engine shafting are met, all major equipment on the ship will be in place or simulated ballasting, ship condition measurement and adjustment will be carried out. Recheck and adjust the axis of the main unit base, gearbox base, and flow channel cylinder pull wire; Confirmation of shaft system reference points and axis.

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