Flexible modification method for helicopter fuselage structure

Abstract

The embodiment of the invention discloses a flexible adding and refitting method for a helicopter fuselage structure, which comprises the following steps of: 1, constructing a three-dimensional digital model of the helicopter fuselage structure, and carrying out virtual adding and refitting design and simulation to obtain adding and refitting schemes for all adding and refitting parts of a helicopter; step 2, carrying out rapid manufacturing and customized production on the refitted parts; and step 3, mounting the refitting part on the helicopter body structure of the helicopter by adopting a fastener quick dismounting and mounting tool, namely implementing the refitting scheme of the helicopter body structure. According to the technical scheme provided by the embodiment of the invention, the problems of incapability of mounting, overlarge gap, overlarge step difference, strong stress assembly and the like after modification due to error accumulation of manufacturing tolerance of parts, manufacturing allowance, irregular deformation of a weak-rigidity helicopter body and the like in an existing modification mode of a helicopter structure are solved.

Description

Technical Field

[0001] This invention relates to, but is not limited to, the field of aerospace manufacturing technology, and particularly to a flexible modification method for helicopter fuselage structures. Background Technology

[0002] Helicopters or other low-speed aircraft often require structural modifications during use due to technological advancements, changes in mission requirements, or structural damage. For example, a simulation terminal may be added to a helicopter, comprising a control box, a prefabricated pod, a communication pod, and left / right mounting brackets, which are connected to the onboard power supply system via cables. Another example is adding a search and rescue mission system to a helicopter, which may involve replacing the equipment rack on the left side of the forward fuselage, the left transition skin, the left stub wing, adding a searchlight bracket, replacing the right stub wing, adding an optoelectronic equipment bracket, replacing the left and right transition skin sections, and configuring system equipment mounting interfaces.

[0003] The modification and alteration of helicopter structures involves numerous operations such as disassembly and installation of components, and structural reinforcement. Traditional methods of helicopter structural modification, which involve new structural design, raw material procurement, new structural manufacturing, assembly tooling design and manufacturing, disassembly of the old structure, and onboard installation of the new structure, suffer from many technical coordination drawbacks. Furthermore, the construction process is cumbersome and lengthy, typically taking at least three months. These traditional modification methods often result in problems such as inability to install components, excessive gaps, large step differences, and stress-induced assembly due to accumulated errors from component manufacturing tolerances, manufacturing allowances, and irregular deformation of the helicopter's weakly rigid airframe. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems. This invention provides a flexible modification method for helicopter fuselage structures to address the problems that arise from the accumulation of errors in existing modification methods for helicopter structures, such as manufacturing tolerances of components, manufacturing allowances, and irregular deformation of the weakly rigid helicopter body. These errors lead to problems such as inability to install, excessive gaps, excessive step differences, and high-stress assembly after modification.

[0005] The technical solution of the present invention: The embodiments of the present invention provide a method for flexible modification of helicopter fuselage structures, comprising: Step 1: Construct a three-dimensional digital model of the helicopter fuselage structure and conduct virtual modification design and simulation to obtain modification schemes for various modification parts used in the helicopter. Step 2: Rapid manufacturing and customized production of the modified parts; Step 3: Using fastener quick disassembly and installation tools, install the modified parts onto the helicopter fuselage, thus implementing the modification scheme for the fuselage structure.

[0006] Optionally, in the flexible modification method for helicopter fuselage structures described above, step 1 includes: Step 11: Use LiDAR 2 and laser scanner 4 to perform a three-dimensional scan of the helicopter fuselage structure 1 to obtain a three-dimensional digital model of the helicopter fuselage structure 1, including: airframe structure, docking surface, docking edge, docking hole position, and hole diameter for modification. Step 12: Based on the modification and upgrade task requirements, perform virtual modification and upgrade assembly and simulation analysis on the three-dimensional digital model generated in Step 11, and form optimized results for various modification requirements through simulation prediction. Step 13: Based on the optimization results obtained from the simulation prediction, output the external dimensions, hole positions, and assembly datum of the added parts structure; Step 14: Determine the disassembly and installation steps, torque requirements, and assembly hole parameters for each modified part.

[0007] Optionally, in the flexible modification method for helicopter fuselage structures described above, step 11 includes: A lidar 2 is used to perform a full-range three-dimensional scan of the helicopter fuselage structure 1, and a preliminary model of the fuselage structure is formed by digital modeling based on the scan data. For abnormal data that deviates significantly from the surroundings, a handheld three-dimensional laser scanner 4 is used to collect supplementary data, and the supplementary data is stitched together with the preliminary model to obtain a three-dimensional digital model of the helicopter fuselage structure 1.

[0008] Optionally, in the flexible modification method for helicopter fuselage structure as described above, in step 12, for a modification requirement, different modification schemes are simulated to predict possible problems, and optimization adjustments are made based on the predicted problems.

[0009] Optionally, in the flexible modification method for helicopter fuselage structures described above, In step 13, each added part has 4 additional assembly holes as assembly references, and the hole positions are fastener hole positions formed by simulation. The assembly hole parameters in step 14 include: the diameter of the four assembly holes is the initial hole diameter; the four assembly holes are evenly distributed on different sides of the added part; and the assembly holes of circular and near-circular parts are symmetrically arranged along the center point or center line.

[0010] Optionally, in the flexible modification method for helicopter fuselage structures described above, step 2 includes: rapidly manufacturing each modified part using additive manufacturing and CNC machining methods, including: Additive manufacturing method: For modified parts with complex shapes or lightweight requirements, 3D printing additive manufacturing method is selected for manufacturing; CNC machining method: Utilizing the high precision machining capabilities and high adaptability of CNC machining centers, modified parts that meet the requirements can be machined.

[0011] Optionally, in the flexible modification method for helicopter fuselage structure described above, the installation method of the modification parts in step 3 is as follows: The disassembly sequence of the helicopter fuselage structure is to operate the closed areas first, and then operate the open areas. The fasteners are to be disassembled in a clockwise direction. The installation process for the modified parts is as follows: first, align the two mounting holes with small coaxiality deviations; adjust the deviations of the other two mounting holes by enlarging the holes; use high-precision locating pins to position the four mounting holes; finally, drill the remaining mounting holes, remove any excess material, install the fasteners and hold them in place, and complete the installation of the modified parts.

[0012] Optionally, in the flexible modification method for helicopter fuselage structures described above, step 3 of the modification process further includes: ensuring the stability of the modification process using real-time monitoring and precision control schemes, including: Real-time monitoring of airframe deformation enables online control of airframe deformation, thereby ensuring the stability of the helicopter airframe during modification and upgrade processes.

[0013] Optionally, in the flexible modification method for helicopter fuselage structures described above, the means of achieving structural stability of the helicopter fuselage include: S1, Before modification, sensors are installed at the key monitoring points 3 on the body structure to monitor the stress, strain and displacement of the body structure in real time. S2 adjusts the modification process in a timely manner during the modification process based on real-time monitoring data and preset safety thresholds and accuracy requirements.

[0014] The beneficial effects of this invention are as follows: This invention provides a flexible modification method for helicopter fuselage structures. By constructing a three-dimensional digital model of the helicopter fuselage structure and through virtual modification design and simulation, modification schemes for various modification parts of the helicopter are obtained. This enables rapid manufacturing and customized production of the modification parts, which are then installed on the helicopter fuselage structure, thus implementing the modification scheme. Furthermore, during the modification process, a real-time monitoring and precision control scheme is used to ensure a stable forward process design method, thereby enabling rapid, efficient, and accurate modification of the helicopter fuselage structure. This ensures that the modified fuselage structure meets the safety and mission performance requirements of the "Helicopter Strength Specification" and minimizes the impact on the normal use of the helicopter. The technical solution provided by this invention has the following beneficial effects: First, it adopts a forward design approach for helicopter airframe structure modification, which reduces repeated trials and errors in the actual modification process. It has the characteristics of strong versatility and high success rate, and can realize modification and alteration without margin and assembly without frame. Secondly, compared with the traditional method, the technical solution provided by this invention can shorten the response time for helicopter airframe structural modifications from no less than 3 months to 1 month, improving efficiency by 3 times. Due to the shortened helicopter structural modification time, the costs of labor, site and other related costs will be reduced accordingly, and the cost of structural modification can be reduced by more than 50%. Third, by utilizing digital design and simulation technology, the impact of modifications on the airframe structure can be accurately assessed before any changes are made, thereby developing the optimal modification plan and ensuring that no irreversible damage is caused to the airframe structure during rapid implementation. Fourth, with the continuous development of aviation technology, new equipment and systems are constantly emerging. Rapid and flexible implementation of airframe structure modification schemes can facilitate the integration of these new technologies into helicopters. Fifth, adopting standardized and flexible modification methods can improve the consistency of modifications between different helicopters; whether it is a helicopter of the same model or a helicopter of different models but with similar modification needs, using the same rapid implementation method can ensure that the quality and performance of the modified helicopter reach a similar level. Attached Figure Description

[0015] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0016] Figure 1 A flowchart illustrating a flexible modification method for helicopter fuselage structure provided in an embodiment of the present invention; Figure 2 This is a set of scanning position diagrams for a 3D all-round scanning of the helicopter fuselage structure using lidar in an embodiment of the present invention; Figure 3 This is another set of scanning position diagrams for using lidar to perform a full-range three-dimensional scan of the helicopter fuselage structure in an embodiment of the present invention; Figure 4 This is a front view of the helicopter fuselage structure data acquired using a handheld 3D laser scanner in an embodiment of the present invention. Figure 5 for Figure 4 The illustrated embodiment shows a side view of the helicopter fuselage structure being supplemented with data using a handheld 3D laser scanner. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0018] As explained in the background section, traditional methods of modifying and retrofitting helicopter airframes often result in problems such as inability to install components, excessive gaps, large step differences, and assembly under high stress due to the accumulation of errors caused by manufacturing tolerances, manufacturing allowances, and irregular deformation of the helicopter's weakly rigid airframe. Furthermore, traditional modification methods significantly impact the original design of the airframe structure, requiring extensive rework and repairs, increasing downtime and maintenance costs, and severely affecting normal operation and mission execution.

[0019] To address the aforementioned issues, this invention provides a flexible modification method for helicopter fuselage structures. Employing a forward process design approach for helicopter fuselage modifications, this method enables rapid, efficient, and precise modification of the helicopter fuselage structure, ensuring that the modified fuselage structure meets the safety and mission performance requirements of the "Helicopter Strength Specification," while minimizing the impact on the normal operation of the helicopter.

[0020] The present invention provides the following specific embodiments, which can be combined with each other. For the same or similar concepts or processes, they may not be described again in some embodiments.

[0021] Figure 1 This is a flowchart illustrating a flexible modification method for a helicopter fuselage structure, provided as an embodiment of the present invention. Figure 1 As shown, the flexible modification method for helicopter fuselage structure provided by this embodiment of the invention includes the following steps: Step 1: Construct a three-dimensional digital model of the helicopter fuselage structure and conduct virtual modification design and simulation to obtain modification schemes for various modification parts used in the helicopter. Step 2: Rapid manufacturing and customized production of the modified parts; Step 3 involves using fastener quick disassembly and installation tools to install the modified parts onto the helicopter's fuselage structure, thus implementing the modification scheme for the fuselage structure. During the modification process in Step 3, real-time monitoring and precision control methods are used to ensure the stability of the modification process.

[0022] The following is a detailed description of the specific implementation methods of the above-mentioned steps of the flexible modification method for helicopter fuselage structure provided by the embodiments of the present invention.

[0023] Step 1: Construct a 3D digital model of the helicopter fuselage structure and perform virtual modification design and simulation; the implementation process of this step is as follows: (1) First, the old structure to be replaced is disassembled, and a laser radar 2 with a full-size measurement accuracy of not less than 0.1 mm is used to perform a rapid, all-round three-dimensional scan of the helicopter fuselage structure 1. Figure 2 , Figure 3 Based on the scanned data, a preliminary model of the fuselage structure is formed through digital modeling. For abnormal data with large deviations from the surroundings, i.e., measurement points with deviations greater than 1 mm, or obstructed areas that cannot be covered by the lidar 2, a handheld 3D laser scanner 4 with a measurement accuracy of not less than 0.1 mm is used to collect supplementary data. Figure 4 , Figure 5 The supplementary data will be spliced ​​with the preliminary model to obtain a precise three-dimensional digital model of the fuselage structure, including: the fuselage structure, the docking surface, docking edge, docking hole position, and hole diameter used for modification. Figure 2 This is a set of scanning position diagrams for using lidar to perform a full-range three-dimensional scan of the helicopter fuselage structure in an embodiment of the present invention. Figure 3 This is another set of scanning position diagrams for using lidar to perform a full-range three-dimensional scan of the helicopter fuselage structure in an embodiment of the present invention; Figure 4 This is a front view of the helicopter fuselage structure data acquired using a handheld 3D laser scanner in an embodiment of the present invention. Figure 5 for Figure 4 The illustrated embodiment shows a side view of the helicopter fuselage structure being supplemented with data using a handheld 3D laser scanner.

[0024] (2) Using professional engineering simulation software, based on the requirements of the modification and alteration task, such as adding equipment mounting points, replacing skin to strengthen the fuselage structure, etc., virtual modification and alteration assembly and simulation analysis are carried out on the generated accurate three-dimensional digital model.

[0025] The specific method is as follows: For a modification requirement, different modification schemes are simulated to predict potential problems, such as structural stress concentration and shear forces caused by assembly gaps. Optimizations are then made based on the predicted problems. For example, if the assembly gap is calculated to be greater than 0.75mm, compensation schemes are provided, such as thickening or widening parts, or positive tolerance manufacturing. This step helps reduce repeated trials and errors in the actual modification process, improves the first-time assembly success rate, and ensures that the flight stability of the modified helicopter is not affected.

[0026] (3) Based on the optimization results obtained from the simulation prediction, output the external dimensions, hole positions and assembly datum of the added parts; in specific implementation, for example, each added part adds 4 assembly holes as assembly datum, and the hole positions are the fastener hole positions formed by simulation (including the above 4 assembly holes). (4) Clearly define the disassembly and installation steps, torque requirements, and assembly hole parameters for each modified part to ensure the standardization and normalization of the entire modification process.

[0027] The assembly hole parameters include: the diameter of the four assembly holes is the initial hole diameter, for example, φ2.5mm; the hole position tolerance is within 0.2mm; they are evenly distributed on different sides of the part to be installed; and the assembly holes of circular and near-circular parts are symmetrically arranged along the center point or center line.

[0028] Step 2: Rapid manufacturing and customized production of the modified parts; This step utilizes advanced additive manufacturing technologies (such as 3D printing) and CNC machining technologies to achieve rapid manufacturing of modified parts; including: (1) For some complex shapes or lightweight modification parts, 3D printing can be used to manufacture them, which can greatly shorten the raw material procurement and production cycle.

[0029] (2) Other parts: The high precision machining capability and high adaptability of CNC machining center can be used to quickly process the modified parts that meet the requirements.

[0030] It should be noted that in the preparation of the modified parts in this step, only the above 4 assembly holes are prepared. The positions of other fastener holes are only marked, and the holes are made on-site according to the installation requirements during the installation process.

[0031] Step 3: Use fastener quick disassembly and installation tools to install the modified parts onto the helicopter fuselage structure; In this embodiment of the invention, the selected and installed fasteners are managed in a standardized manner. A set of quick disassembly and installation tools specifically designed for helicopter fuselage structure modification is used, including: an adjustable intelligent electric torque wrench, an electric digital integrated high-lock bolt installation device, and high-precision positioning pins. These tools can improve the speed and accuracy of disassembling and installing bolts, connectors, and other connecting components. The specific installation method is as follows: (1) The disassembly sequence of the helicopter fuselage structure is to operate the closed area first and then the open area. The fasteners are disassembled in a clockwise direction.

[0032] (2) The installation process of the modified parts is to prioritize the connection of the two assembly holes that are in good condition (i.e., the two coaxiality fit deviations are small). The deviations of the other two assembly holes are adjusted by enlarging the holes to a diameter of φ4mm. The four assembly holes are positioned using high-precision positioning pins. Finally, the other mounting holes are drilled, excess materials are cleaned, fasteners are installed and fixed, and the installation of the modified parts is completed.

[0033] It should be noted that in step 3, during the modification and upgrading of the helicopter airframe (during the disassembly of original components and the installation of modified parts), a real-time monitoring and precision control scheme is used to ensure the stability of the modification and upgrading process. The specific implementation scheme is as follows: real-time monitoring of the deformation of the airframe structure is carried out to achieve online control of the deformation of the airframe structure, thereby ensuring the stability of the airframe structure during the modification and upgrading process.

[0034] In practice, the methods to achieve structural stability of the helicopter include: Before the modification process, multiple sensors were installed in key parts of the aircraft structure, such as... Figure 4 , Figure 5 The key monitoring point 3 shown is located at horizontal measurement points, the main frame beam axis, and the intersection of the power transmission lines, etc., to monitor changes in parameters such as stress, strain, and displacement of the aircraft structure in real time. Based on the real-time monitoring data, combined with preset safety thresholds and accuracy requirements, adjustments are made to the modification process during the upgrade. For example, if the stress in a certain part is found to be close to the dangerous value, the current operation is immediately stopped, and the upgrade plan or assembly process is inspected and corrected to ensure the safety of the aircraft structure and the accuracy of the upgrade.

[0035] This invention provides a flexible modification method for helicopter fuselage structures. By constructing a three-dimensional digital model of the helicopter fuselage structure and through virtual modification design and simulation, modification schemes for various modification parts are obtained. This enables rapid manufacturing and customized production of the modification parts, which are then installed on the helicopter fuselage structure, thus implementing the modification scheme. Furthermore, during the modification process, a real-time monitoring and precision control scheme is used to ensure stable forward process design, enabling rapid, efficient, and accurate modification of the helicopter fuselage structure. This ensures that the modified fuselage structure meets the safety and mission performance requirements of the "Helicopter Strength Specification" and minimizes the impact on the normal operation of the helicopter. The technical solution provided by this invention has the following beneficial effects: First, it adopts a forward design approach for helicopter airframe structure modification, which reduces repeated trials and errors in the actual modification process. It has the characteristics of strong versatility and high success rate, and can realize modification and alteration without margin and assembly without frame. Secondly, compared with the traditional method, the technical solution provided by this invention can shorten the response time for helicopter airframe structural modifications from no less than 3 months to 1 month, improving efficiency by 3 times. Due to the shortened helicopter structural modification time, the costs of labor, site and other related costs will be reduced accordingly, and the cost of structural modification can be reduced by more than 50%. Third, by utilizing digital design and simulation technology, the impact of modifications on the airframe structure can be accurately assessed before any changes are made, thereby developing the optimal modification plan and ensuring that no irreversible damage is caused to the airframe structure during rapid implementation. Fourth, with the continuous development of aviation technology, new equipment and systems are constantly emerging. Rapid and flexible implementation of airframe structure modification schemes can facilitate the integration of these new technologies into helicopters. Fifth, adopting standardized and flexible modification methods can improve the consistency of modifications between different helicopters; whether it is a helicopter of the same model or a helicopter of different models but with similar modification needs, using the same rapid implementation method can ensure that the quality and performance of the modified helicopter reach a similar level.

[0036] The technical solution provided by this invention is beneficial for users to manage and schedule their fleet in a unified manner, and also facilitates subsequent maintenance and support work.

[0037] The following specific embodiments illustrate the implementation of the flexible modification method for helicopter fuselage structures provided by the present invention.

[0038] Example 1: Installing a simulation terminal on a helicopter Based on actual needs, a simulation terminal was installed on a helicopter. The simulation terminal includes a control box, a prefabricated pod, a communication pod, and left / right mounting brackets, and is interconnected with the onboard power supply system via connecting cables.

[0039] (1) First, a laser radar with a full-size measurement accuracy of not less than 0.1 mm is used to perform a rapid and comprehensive three-dimensional scan and digital modeling of the helicopter fuselage structure. For abnormal data with large deviations from the surroundings, i.e. measurement points with a deviation of more than 1 mm, or areas blocked by the laser that cannot be covered, a handheld three-dimensional laser scanner with a measurement accuracy of not less than 0.1 mm is used to collect data and obtain an accurate three-dimensional data model of the fuselage structure, including the docking hole diameter / position, docking edge, docking surface, etc. (2) Using professional engineering simulation software DTAS3D and ABAQUS, virtual modification and assembly and simulation analysis were performed on the generated digital model according to the requirements of the simulation terminal installation task. It was found that the outline of the simulation terminal and the helicopter fuselage structure had a large deviation, with a step difference of 2.5mm, which was caused by the deformation of the fuselage structure. A compensation scheme for the docking interface was proposed. The docking interface was designed according to the actual size of the fuselage structure to eliminate the 2.5mm step difference, and the fastener positions were appropriately allocated.

[0040] (3) According to the simulation results, output the simulated terminal dimensions and assembly reference. Add 4 assembly holes on each part as assembly reference. The hole position is the simulated fastener hole position, the hole diameter is the initial hole diameter of the fastener φ2.5mm, the hole position tolerance is 0.2mm, and they are evenly distributed on different sides.

[0041] (4) Utilize the high precision machining capability and high adaptability of CNC machining centers to quickly process parts that meet the requirements.

[0042] (5) Standardized management of selected and installed fasteners, using a set of quick disassembly and installation tools specifically designed for helicopter fuselage structure modifications, including adjustable intelligent electric torque wrenches, electric digital integrated high-strength bolt installation equipment, high-precision positioning pins, and other tools. These tools can improve the speed and accuracy of disassembling and installing bolts, joints, and other connecting components.

[0043] (6) The installation process of the simulated terminal is to prioritize the connection of the two assembly holes that are in good condition. If the other two assembly holes are in deviation, they are adjusted by enlarging the holes to a diameter of φ4mm. The four assembly holes are positioned using high-precision positioning pins. Finally, the other installation holes are drilled, excess materials are cleaned, fasteners are installed and fixed, and the installation of the new parts is completed.

[0044] (7) During the modification process, multiple sensor contacts were installed at key parts of the fuselage. The monitoring locations were selected from horizontal measurement points, the axis of the main frame beam, and the intersection of the power transmission, to monitor the changes in stress, strain, displacement, and other parameters of the fuselage structure in real time. The monitored data met the preset safety thresholds and accuracy requirements, and the installation of the simulation terminal was successfully completed.

[0045] Example 2: Installing a search and rescue mission system on a helicopter Modification work was carried out on a helicopter to add a search and rescue mission system. This included replacing the equipment rack on the left side of the forward fuselage, the left transition skin, replacing the left stub wing, adding a searchlight bracket, replacing the right stub wing, adding an electro-optical equipment bracket, replacing the left and right transition skins, and configuring system equipment installation interfaces.

[0046] (1) First, the old structure to be replaced is disassembled. A laser radar with a full-size measurement accuracy of not less than 0.1mm is used to quickly and comprehensively scan and digitally model the helicopter fuselage structure. For abnormal data with large deviations from the surroundings, i.e. measurement points with deviations greater than 1mm, and areas blocked by the laser that cannot be covered, a handheld three-dimensional laser scanner with a measurement accuracy of not less than 0.1mm is used to collect data and obtain an accurate three-dimensional data model of the fuselage structure, including the docking hole diameter / position, docking edge, docking surface, etc. (2) Using professional engineering simulation software DTAS3D and ABAQUS, virtual assembly and simulation analysis were performed on the generated digital model according to the requirements of the modified search and rescue mission system. It was found that the assembly gap between the newly added structures such as skin and brackets and the helicopter body structure reached 1.5mm, which exceeded the allowable adjustment range for padding. The reason was the deformation of the helicopter body structure. A compensation solution was proposed, which eliminated the gap by thickening the skin and brackets.

[0047] (3) According to the simulation results, output the external dimensions and assembly reference of the search and rescue mission system. Add 4 assembly holes for each part as assembly reference. The hole position is the fastener hole position after simulation. The hole diameter is the initial hole diameter of the fastener φ2.5mm. The hole position tolerance is 0.2mm. They are evenly distributed on different sides.

[0048] (4) For skin and bracket parts, 3D printing technology is used to greatly shorten the raw material procurement and production cycle.

[0049] (5) For connector parts, the high precision machining capability and high adaptability of CNC machining centers can be used to quickly produce parts that meet the requirements.

[0050] (6) Standardized management of selected and installed fasteners, using a set of quick disassembly and installation tools specifically designed for helicopter fuselage structure modifications, including adjustable intelligent electric torque wrenches, electric digital integrated high-strength bolt installation equipment, high-precision positioning pins, and other tools. These tools can improve the speed and accuracy of disassembling and installing bolts, joints, and other connecting components.

[0051] (7) The installation process of the search and rescue mission system is to prioritize the connection of the two assembly holes that are in good condition. If the other two assembly holes are in deviation, they are adjusted by enlarging the holes to a diameter of φ4mm. The four assembly holes are positioned using high-precision positioning pins. Finally, the other installation holes are drilled, excess materials are cleaned, fasteners are installed and fixed, and the installation of new parts is completed.

[0052] (8) During the modification process, multiple sensor contacts are installed at key parts of the fuselage. The locations are selected from horizontal measurement points, the axis of the main frame beam, and the intersection of the power transmission, in order to monitor the changes in stress, strain, displacement and other parameters of the fuselage structure in real time.

[0053] While the embodiments disclosed in this invention are as described above, they are merely illustrative of the embodiments to facilitate understanding of the invention and are not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for flexible modification of helicopter fuselage structures, characterized in that, include: Step 1: Construct a three-dimensional digital model of the helicopter fuselage structure and conduct virtual modification design and simulation to obtain modification schemes for various modification parts used in the helicopter. Step 2: Rapid manufacturing and customized production of the modified parts; Step 3: Using fastener quick disassembly and installation tools, install the modified parts onto the helicopter fuselage, thus implementing the modification scheme for the fuselage structure.

2. The flexible modification method for helicopter fuselage structure according to claim 1, characterized in that, Step 1 includes: Step 11: A three-dimensional scan of the helicopter fuselage structure (1) is performed using a lidar (2) and a laser scanner (4) to obtain a three-dimensional digital model of the helicopter fuselage structure (1), including: the fuselage structure, the docking surface, docking edge, docking hole position, and hole diameter for modification; Step 12: Based on the modification and upgrade task requirements, perform virtual modification and upgrade assembly and simulation analysis on the three-dimensional digital model generated in Step 11, and form optimized results for various modification requirements through simulation prediction. Step 13: Based on the optimization results obtained from the simulation prediction, output the external dimensions, hole positions, and assembly datum of the added parts structure; Step 14: Determine the disassembly and installation steps, torque requirements, and assembly hole parameters for each modified part.

3. The flexible modification method for helicopter fuselage structure according to claim 2, characterized in that, Step 11 includes: A lidar (2) is used to perform a full-range three-dimensional scan of the helicopter fuselage structure (1), and a preliminary model of the fuselage structure is formed by digital modeling based on the scan data. For abnormal data that deviates significantly from the surrounding data, a handheld three-dimensional laser scanner (4) is used to collect additional data, and the collected data is spliced ​​with the preliminary model to obtain a three-dimensional digital model of the helicopter fuselage structure (1).

4. The flexible modification method for helicopter fuselage structure according to claim 2, characterized in that, In step 12, for a modification requirement, different modification schemes are simulated to predict potential problems, and optimizations are made based on the predicted problems.

5. The flexible modification method for helicopter fuselage structure according to claim 2, characterized in that, In step 13, each added part has 4 additional assembly holes as assembly references, and the hole positions are fastener hole positions formed by simulation. The assembly hole parameters in step 14 include: the diameter of the four assembly holes is the initial hole diameter; the four assembly holes are evenly distributed on different sides of the added part; and the assembly holes of circular and near-circular parts are symmetrically arranged along the center point or center line.

6. The flexible modification method for helicopter fuselage structure according to any one of claims 1 to 5, characterized in that, Step 2 includes: employing additive manufacturing and CNC machining methods to rapidly manufacture each modified part, including: Additive manufacturing method: For modified parts with complex shapes or lightweight requirements, 3D printing additive manufacturing method is selected for manufacturing; CNC machining method: Utilizing the high precision machining capabilities and high adaptability of CNC machining centers, modified parts that meet the requirements can be machined.

7. The flexible modification method for helicopter fuselage structure according to any one of claims 1 to 5, characterized in that, The installation method for adding the modified parts in step 3 is as follows: The disassembly sequence of the helicopter fuselage structure is to operate the closed areas first, and then operate the open areas. The fasteners are to be disassembled in a clockwise direction. The installation process for the modified parts is as follows: first, align the two mounting holes with small coaxiality deviations; adjust the deviations of the other two mounting holes by enlarging the holes; use high-precision locating pins to position the four mounting holes; finally, drill the remaining mounting holes, remove any excess material, install the fasteners and hold them in place, and complete the installation of the modified parts.

8. The flexible modification method for helicopter fuselage structure according to claim 7, characterized in that, Step 3, the modification and alteration of the helicopter airframe, also includes: ensuring the stability of the modification and alteration process using real-time monitoring and precision control schemes, including: Real-time monitoring of airframe deformation enables online control of airframe deformation, thereby ensuring the stability of the helicopter airframe during modification and upgrade processes.

9. The flexible modification method for helicopter fuselage structure according to claim 8, characterized in that, Methods for achieving structural stability in helicopters include: S1, Before modification, sensors are installed at the key monitoring points (3) on the body structure to monitor the stress, strain and displacement of the body structure in real time. S2 adjusts the modification process in a timely manner during the modification process based on real-time monitoring data and preset safety thresholds and accuracy requirements.

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