Continuous fiber reinforced composite unmanned aerial vehicle integrated skeleton printing method and device

Abstract

The invention discloses a continuous fiber reinforced composite unmanned aerial vehicle integrated skeleton printing method and device, and relates to the technical field of unmanned aerial vehicles and additive manufacturing. The method comprises the following steps: drawing an integrated skeleton boundary of the unmanned aerial vehicle based on a pneumatic outline and a minimum thickness requirement specified by a skin of the unmanned aerial vehicle; designing an internal structure of the unmanned aerial vehicle integrated skeleton based on the drawn boundary of the unmanned aerial vehicle integrated skeleton in combination with the anisotropic characteristic of the continuous fiber reinforced composite material and the unmanned aerial vehicle stress condition obtained through simulation analysis; based on the boundary of the unmanned aerial vehicle integrated skeleton and the internal structure of the unmanned aerial vehicle integrated skeleton, a printing path and a local feature processing strategy are planned in combination with a continuous fiber printing process and local feature bearing requirements; and continuous fiber printing equipment is used for printing the unmanned aerial vehicle integrated framework, and post-processing is carried out. The problems that an existing unmanned aerial vehicle framework machining mode is tedious in assembly, low in material utilization rate and insufficient in light weight are solved.

Description

Technical Field

[0001] This application relates to the fields of unmanned aerial vehicles (UAVs) and additive manufacturing technology, and in particular to a method and apparatus for printing an integrated skeleton of a UAV made of continuous fiber reinforced composite material. Background Technology

[0002] Unmanned aerial vehicles (UAVs) are widely used in critical missions such as disaster monitoring, material delivery, and personnel search and rescue. The UAV's frame, as the core structure supporting all key components, plays a crucial role in the overall performance of the UAV. Its key indicators, such as weight, strength, and rigidity, directly determine the UAV's flight performance, load-bearing capacity, and service life, and are key factors affecting the efficient, stable, and safe operation of the UAV.

[0003] Currently, traditional UAV frame structures generally employ a split beam-rib structure. In terms of material selection and processing methods, they are mainly divided into two types: metal materials and composite materials. For metal frames, a split machining method is typically used, where each component is individually machined and then connected by riveting or welding. Composite material frames, on the other hand, are assembled by cutting the components separately and then gluing or mechanically joining them. First, the composite material is cut to the appropriate shape and size according to design requirements, and then the various components are combined using gluing or mechanical connections to form a complete frame structure.

[0004] However, traditional metal frame split machining has the problem of low material utilization; composite material frames are complicated to connect and assemble after split cutting and cannot meet the requirements of drones for lightweighting. Summary of the Invention

[0005] In this embodiment of the application, a method for printing an integrated skeleton of a drone using continuous fiber reinforced composite material is provided, which solves the problems of low material utilization and insufficient lightweighting in existing drone skeleton processing methods.

[0006] In a first aspect, embodiments of this application provide a method for printing an integrated frame of a drone made of continuous fiber reinforced composite material. The method includes: extracting the aerodynamic profile of the drone using 3D software; drawing the boundary of the integrated frame based on the aerodynamic profile and the minimum thickness requirement specified for the drone skin; designing the internal structure of the integrated frame based on the drawn boundary, combined with the anisotropic characteristics of the continuous fiber reinforced composite material and the stress conditions of the drone obtained through simulation analysis; planning the printing path and local feature processing strategy for the integrated frame based on the boundary and internal structure of the integrated frame, combined with the continuous fiber printing process and local feature load-bearing requirements; wherein the printing path is planned as a continuous path, interpolation is performed before and after each feature point of the integrated frame to set deceleration intervals, and the coordinates of the deceleration start point and deceleration end point corresponding to each deceleration interval are calculated; printing the integrated frame of the drone using a continuous fiber printing device based on the printing path and local feature processing strategy; and post-processing the integrated frame of the drone after printing.

[0007] In one possible implementation, based on the drawn UAV integrated skeleton boundary, combined with the anisotropic properties of the continuous fiber reinforced composite and the UAV stress conditions obtained through simulation analysis, the internal structure of the UAV integrated skeleton is designed, including: the fiber material of the continuous fiber reinforced composite is at least one of carbon fiber, glass fiber, basalt fiber, and aramid fiber; the fiber specification range is [1K, 12K]; the matrix material of the continuous fiber reinforced composite is a thermosetting resin, including at least one of epoxy resin, phenolic resin, bismaleimide resin, and polyimide resin; the fiber mass fraction of the continuous fiber reinforced composite ranges from [35%, 70%]; the anisotropic properties of the continuous fiber reinforced composite are assigned values ​​through measured performance; the UAV stress conditions are given simplified constraints in the finite element simulation analysis software based on the lift changes during flight attitude transformation; the internal structure of the UAV integrated skeleton is designed based on the simulation deformation evaluation and the principle of prioritizing straight lines in the printing path.

[0008] In one possible implementation, interpolation is performed before and after each feature point of the integrated UAV skeleton to set deceleration intervals, and the starting and ending coordinates of deceleration for each deceleration interval are calculated, including: the formula for calculating the starting coordinates of deceleration is: ; ;in, Let x be the x-coordinate of the deceleration starting point. An array to store the coordinates of feature points along the printing path, For array index variables, The x-coordinate of the feature point preceding the deceleration interval. This is the deceleration ratio. The x-coordinate of the feature point following the deceleration interval. The ordinate of the deceleration starting point. The ordinate of the feature point preceding the deceleration interval. Here is the ordinate of the next feature point after the deceleration interval; the formula for calculating the coordinates of the deceleration endpoint is: ; ;in, Let x be the x-coordinate of the deceleration endpoint. The vertical coordinate is the endpoint of the deceleration.

[0009] In one possible implementation, the formula for calculating the deceleration ratio is: ;in, This is the deceleration ratio. To reduce deceleration distance, The characteristic length is denoted as .

[0010] In one possible implementation, the continuous fiber printing process includes at least one of in-situ impregnation printing, prepreg printing, and prepreg impregnation printing; in the continuous fiber printing process, the nozzle orifice diameter ranges from [0.8 mm to 3 mm]; the actual printing speed ranges from [0.1 m / min to 8 m / min]; the printing layer height ranges from [0.2 mm to 0.6 mm]; the printing offset ranges from [0.8 mm to 3.5 mm]; the printing nozzle temperature ranges from [100 °C to 250 °C]; the printing gas flow rate is from [10 L / min to 25 L / min]; and the printing ultraviolet wavelength range is from [320 nm to 395 nm].

[0011] In one possible implementation, local features include corners, intersections, arcs, and cantilever structures; local feature processing strategies include a heat dissipation and rapid cooling strategy, a filament dispersion and hot pressing strategy, a variable speed strategy, and a pad support and variable posture printing strategy; wherein, a heat dissipation and rapid cooling strategy is used at corners; a filament dispersion and hot pressing strategy is used at intersections; a variable speed strategy is used at arcs; and a pad support or variable posture printing strategy is used at cantilever structures.

[0012] In one possible implementation, after the printing is completed, the integrated frame of the drone is post-processed, including: post-processing includes curing, polishing and painting; the curing process adopts the vacuum embedding method for irregular parts, and the embedding material includes at least one of silicone, silicon powder, salt, quartz sand, steel balls and ceramic slurry; throughout the curing process, a vacuum pressure of 0.08MPa-0.095MPa is maintained.

[0013] One possible implementation also includes: based on equations Determine the calculated printing speed; where, For the calculated printing speed, The local radius of curvature is used to determine whether the calculated printing speed is within the range of the actual printing speed. If the calculated printing speed is within the range of the actual printing speed, the calculated printing speed is selected for printing the integrated drone frame. If the calculated printing speed is not within the range of the actual printing speed, the calculated printing speed is adjusted. When the calculated printing speed is less than 0.1 m / min, the actual minimum allowable printing speed of 0.1 m / min is used for printing the integrated drone frame. When the calculated printing speed is greater than 8 m / min, the actual maximum allowable printing speed of 8 m / min is used for printing the integrated drone frame.

[0014] Secondly, embodiments of this application provide a continuous fiber reinforced composite unmanned aerial vehicle (UAV) integrated skeleton printing device. The device includes: an extraction module for extracting the aerodynamic outline of the UAV using 3D software; a drawing module for drawing the boundary of the integrated UAV skeleton based on the aerodynamic outline and the minimum thickness requirement specified for the UAV skin; a design module for designing the internal structure of the integrated UAV skeleton based on the drawn boundary, combined with the anisotropic characteristics of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis; a planning module for planning the printing path and local feature processing strategy of the integrated UAV skeleton based on the boundary and internal structure of the integrated UAV skeleton, combined with the continuous fiber printing process and local feature load-bearing requirements; wherein the printing path is planned as a continuous path, interpolation is performed before and after each feature point of the integrated UAV skeleton to set deceleration intervals, and the coordinates of the deceleration start point and deceleration end point corresponding to each deceleration interval are calculated; and a printing module for printing the integrated UAV skeleton using a continuous fiber printing device based on the printing path and local feature processing strategy, and performing post-processing on the integrated UAV skeleton after printing.

[0015] One or more technical solutions provided in the embodiments of this application have at least the following technical effects: This application provides a method for printing an integrated UAV skeleton using continuous fiber reinforced composite materials. The method extracts the aerodynamic profile of the UAV using 3D software. Based on the aerodynamic profile and the minimum thickness requirements specified for the UAV skin, the boundary of the integrated UAV skeleton is drawn. Based on the drawn boundary, combined with the anisotropic properties of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis, the internal structure of the integrated UAV skeleton is designed. Based on the boundary and internal structure of the integrated UAV skeleton, and considering the continuous fiber printing process and local feature load-bearing requirements, the printing path and local feature processing strategy of the integrated UAV skeleton are planned. The printing path is planned as a continuous path, and interpolation operations are performed before and after each feature point of the integrated UAV skeleton to set deceleration intervals, and the coordinates of the deceleration start and end points corresponding to each deceleration interval are calculated. Based on the printing path and local feature processing strategy, the integrated UAV skeleton is printed using a continuous fiber printing device, and post-processing is performed after printing. This method solves the problems of cumbersome assembly, low material utilization, and insufficient lightweighting in existing UAV skeleton processing methods. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart illustrating a method for printing an integrated skeleton of a continuous fiber reinforced composite unmanned aerial vehicle (UAV) according to an embodiment of this application; Figure 2 This is an aerodynamic outline diagram of an unmanned aerial vehicle (UAV) provided in an embodiment of this application. Figure 3 A schematic diagram of the integrated frame of an unmanned aerial vehicle provided in an embodiment of this application; Figure 4 A schematic diagram illustrating the printing path for the integrated skeleton of a planned unmanned aerial vehicle (UAV) provided in an embodiment of this application; Figure 5 This is a post-processed physical image of the integrated frame of the unmanned aerial vehicle provided in an embodiment of this application; Figure 6 This is a schematic diagram of an integrated skeleton printing device for a continuous fiber reinforced composite drone provided in an embodiment of this application.

[0018] Reference numerals: 1-wing frame; 2-fuselage frame; 3-1-left arm frame; 3-2-right arm frame; 4-arm linkage; 5-tail thruster linkage. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] The following description of some technologies involved in the embodiments of this application is provided to aid understanding and should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, some descriptions of well-known functions and structures are omitted in the following description.

[0021] This application provides a method for printing an integrated skeleton for a continuous fiber reinforced composite unmanned aerial vehicle (UAV), such as... Figure 1 As shown, the method includes steps S101 to S105. Wherein, Figure 1 This is merely one execution order shown in the embodiments of this application and does not represent the only execution order for a continuous fiber reinforced composite UAV integrated skeleton printing method. The execution order can be adjusted to achieve the desired final result. Figure 1 The steps shown can be performed in parallel or in reverse order.

[0022] S101: Extract the aerodynamic shape profile of the UAV using 3D software.

[0023] Specifically, the 3D software used in this application can be NX.

[0024] Figure 2 This is an aerodynamic outline diagram of an unmanned aerial vehicle (UAV) provided in an embodiment of this application. The UAV in this application is a compound-wing UAV combining a multi-rotor and a fixed-wing design.

[0025] S102: Draw the integrated skeleton boundary of the UAV based on the aerodynamic profile and the minimum thickness requirements specified for the UAV skin.

[0026] Specifically, the integrated skeleton boundary of the UAV includes the three-dimensional boundaries of the UAV skin in terms of length, width, and height.

[0027] Figure 3This is a schematic diagram of an integrated UAV frame provided in an embodiment of this application. The integrated UAV frame of this application is a continuous fiber reinforced composite wing UAV integrated frame. The integrated UAV frame includes a wing frame 1, a fuselage frame 2, a left arm frame 3-1, and a right arm frame 3-2. The wing frame 1 is connected to the fuselage frame 2, the left arm frame 3-1, and the right arm frame 3-2 by interlocking. The tail of the left arm frame 3-1 and the right arm frame 3-2 are connected by an arm connecting rod 4. The fuselage frame 2 is connected to the tail thruster by a tail thruster connecting rod 5.

[0028] S103: Based on the drawn boundary of the integrated UAV skeleton, combined with the anisotropic properties of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis, the internal structure of the integrated UAV skeleton is designed.

[0029] Based on the drawn boundary of the integrated UAV skeleton, combined with the anisotropic properties of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis, the internal structure of the integrated UAV skeleton is designed, including the following contents.

[0030] The fiber material of the continuous fiber reinforced composite is at least one of carbon fiber, glass fiber, basalt fiber, and aramid fiber. The fiber specifications range from [1K, 12K].

[0031] Specifically, K is a unit that measures the number of monofilaments in a fiber bundle. For some connection parts with high flexibility requirements and complex shapes, low K-number fibers can be selected; while for load-bearing beams and other parts with large loads and high strength and stiffness, high K-number fibers are selected to optimize the overall performance of the skeleton.

[0032] The matrix material of the continuous fiber reinforced composite is a thermosetting resin, including at least one of epoxy resin, phenolic resin, bismaleimide resin and polyimide resin.

[0033] Specifically, the base material is vacuum-packed and then frozen for storage. After thawing, it is unsealed and preheated to the preset temperature before use. Vacuum packaging effectively isolates the material from air, preventing oxidation, moisture absorption, and other reactions during storage, thus ensuring the material's performance stability. Frozen storage reduces the material's chemical reactivity, extends its shelf life, and ensures that the material retains good processing and physicochemical properties during use.

[0034] When using the matrix material, it must first be thawed, then unpacked and preheated to the preset temperature. The purpose of preheating is to bring the material to a suitable process temperature, improve its fluidity and wettability, so that it can fully impregnate the fiber when added to the material pool and compounded with the fiber, thereby improving the interfacial bonding strength and overall performance of the composite material. The preset temperature can be [60℃, 100℃].

[0035] The fiber mass fraction of continuous fiber reinforced composites ranges from [35%, 70%], and the anisotropic properties of continuous fiber reinforced composites are assigned values ​​through measured performance.

[0036] Specifically, for load-bearing beams that mainly bear tensile and compressive loads, materials with a higher fiber mass fraction can be selected; while for some connection parts that require a certain deformation capacity to buffer impact, the fiber mass fraction can be appropriately reduced.

[0037] Continuous fiber-reinforced composites exhibit varying mechanical properties in different directions due to the different orientations of their internal fibers. Obtaining performance data in these different directions through actual measurements and assigning values ​​to anisotropic characteristics accurately reflects the material's true performance. This helps in the design and analysis of UAV frames, enabling more precise prediction of the frame's mechanical response under various operating conditions, ensuring the rationality and reliability of the design. For example, when designing the frame structure, the fiber orientation and structural layout can be rationally determined based on the material's strength and stiffness data in different directions, allowing the frame to fully utilize the material's performance advantages while avoiding structural failures caused by inaccurate estimations of material properties.

[0038] The stress conditions of the UAV are simplified by applying constraints to the lift changes during flight attitude transformation in the finite element simulation analysis software Abaqus, and then stress and deformation simulations are performed under maximum static load.

[0039] Specifically, simplified constraints are constraints applied after reasonably simplifying the complex factors in the actual stress conditions of the UAV, while ensuring the accuracy and reliability of the simulation results. This simplified constraint method allows for the simulation of the UAV's stress conditions under different flight attitudes in finite element simulation analysis software, thus obtaining the UAV's stress conditions. During the simulation, characteristic parts or truncated parts are used for testing to iteratively correct material properties and load parameters. The specific simulation steps include: model import, material assignment, mesh generation, boundary constraints, load assignment, analysis step settings, and result analysis.

[0040] The internal structure of the integrated frame of the drone is designed based on the principle of simulation deformation assessment and straight line priority in printing path to reduce fiber buckling.

[0041] Specifically, evaluating the simulated deformation allows us to analyze whether the magnitude, direction, and distribution of the deformation are within acceptable limits. If the evaluation reveals that certain areas have excessive deformation, these areas will need to be reinforced during the design of the internal structure.

[0042] S104: Based on the boundary and internal structure of the integrated UAV skeleton, and combining continuous fiber printing technology with local feature bearing requirements, the printing path and local feature processing strategy of the integrated UAV skeleton are planned. Specifically, the printing path is planned as a continuous path. Interpolation operations are performed before and after each feature point of the integrated UAV skeleton to set deceleration intervals, and the coordinates of the deceleration start and end points corresponding to each deceleration interval are calculated.

[0043] Continuous fiber printing processes include at least one of in-situ impregnation printing, prepreg printing, and prepreg impregnation printing.

[0044] The prepreg is impregnated and bundled by two rollers and then frozen for storage. During the printing process, the prepreg is spread out by passive feeding and pre-shaped by air cooling or light curing.

[0045] In continuous fiber printing, the nozzle orifice diameter ranges from 0.8mm to 3mm. The actual printing speed ranges from 0.1m / min to 8m / min. The printed layer height ranges from 0.2mm to 0.6mm. The printing offset ranges from 0.8mm to 3.5mm. The printing nozzle temperature ranges from 100℃ to 250℃. The printing gas flow rate is from 10L / min to 25L / min. The printing ultraviolet wavelength range is from 320nm to 395nm.

[0046] Local features include corners, intersections, curves, and cantilever structures. Local feature processing strategies include precipitate cooling, filament dispersion and hot pressing, variable speed printing, and pad support and variable orientation printing. Specifically, precipitate cooling is used at corners. Filament dispersion and hot pressing are used at intersections. Variable speed printing is used at curves. Pad support or variable orientation printing is used at cantilever structures.

[0047] Figure 4 This diagram illustrates the printing path for an integrated UAV skeleton as provided in an embodiment of this application. Based on continuous fiber printing technology and local feature bearing requirements, the 3D printing path and local feature processing strategy for the integrated UAV skeleton were planned.

[0048] For the continuous fiber reinforced composite printing process, in-situ impregnation printing was employed. Specific parameters were set as follows: nozzle orifice diameter of 1mm, actual printing speed of 6m / min, nozzle temperature controlled at 120℃, layer height of 0.4mm, and printing offset of 1mm. During printing, in-situ pre-shaping was performed using ultraviolet light illumination and air cooling, with an air flow rate of 15L / min and an ultraviolet wavelength of 365nm. Furthermore, for feature points, the distance between interpolation deceleration points was set to 1-2mm, and the deceleration speed range was 0.1-3m / min.

[0049] Interpolation is performed before and after each feature point of the integrated UAV skeleton to set the deceleration interval, and the coordinates of the deceleration start point and deceleration end point corresponding to each deceleration interval are calculated, including the following:

[0050] The formula for calculating the coordinates of the deceleration starting point is: . .in, Let x be the x-coordinate of the deceleration starting point. An array to store the coordinates of feature points along the printing path, For array index variables, The x-coordinate of the feature point preceding the deceleration interval. This is the deceleration ratio. The x-coordinate of the feature point following the deceleration interval. The ordinate of the deceleration starting point The ordinate of the feature point preceding the deceleration interval. This represents the ordinate of the next feature point after the deceleration interval.

[0051] Specifically, in 3D printing path planning, the printing path is composed of a series of discrete feature points connected together. These feature points record the spatial coordinate information of the print head at different positions. For example, when printing an integrated skeleton for a drone, these features correspond to key turning points, connection points, and other locations in the skeleton structure. Array index variable, used for traversal. Each element in the array, by changing The value of allows access to different feature points along the printing path in sequence. For example, when When, it indicates that the first feature point has been visited; when When, it indicates that the second feature point has been visited, and so on. Let x be the x-coordinate of the feature point preceding the deceleration interval. In the printing path, two adjacent feature points define a line segment in the movement of the print head. It is the horizontal coordinate of the starting feature point of this line segment. It is the ordinate of the feature point preceding the deceleration interval, that is, the ordinate of the starting feature point of the line segment in the vertical direction. This is the x-coordinate of the feature point following the deceleration interval, i.e., the horizontal x-coordinate of the end feature point of the current line segment in the printing path. It is the ordinate of the feature point after the deceleration interval, that is, the ordinate of the end feature point of the current line segment in the vertical direction.

[0052] The formula for calculating the coordinates of the deceleration endpoint is: . .in, Let x be the x-coordinate of the deceleration endpoint. The vertical coordinate is the endpoint of the deceleration.

[0053] The formula for calculating the deceleration ratio is: .in, This is the deceleration ratio. To reduce deceleration distance, Characteristic length. Deceleration ratio. This is a value between 0 and 1, used to determine the proportion of the deceleration interval within the entire distance between adjacent feature points. By adjusting the deceleration ratio, the magnitude and range of deceleration can be controlled, thus affecting the change in the printhead's movement speed near the feature point. Deceleration distance This represents the straight-line distance the print head travels from its normal printing speed to its minimum speed. In actual printing, the selection of this deceleration distance needs to comprehensively consider factors such as printing accuracy requirements, the characteristics of the printing material, and the performance of the print head. For example, for some local features with extremely high precision requirements, a larger deceleration distance needs to be set to ensure that the print head has sufficient time and distance to adjust its movement, thereby ensuring print quality. Feature length This refers to the straight-line distance between two adjacent feature points. It reflects the length information of adjacent line segments on the printing path. Calculating the feature length helps to dynamically adjust the deceleration ratio according to different line segment lengths, enabling smoother speed changes at the transition points between line segments of different lengths.

[0054] S105: Based on the printing path and local feature processing strategy, a continuous fiber printing device is used to print the integrated frame of the UAV. After printing, the integrated frame of the UAV is post-processed.

[0055] Figure 5 This image shows a post-processed physical model of the integrated UAV frame provided in an embodiment of this application. The integrated UAV frame made using the 3D printing method of this application, consisting of continuous fiber-reinforced thermosetting composite wing, boasts high printing precision, high printing efficiency, and low cost. It significantly shortens the overall assembly time and reduces weight by more than 20% compared to frames formed using traditional manufacturing processes, meeting the requirements for 25kg-class industrial flight applications.

[0056] After printing, post-processing is performed on the integrated frame of the drone, including the following:

[0057] Post-processing includes curing, sanding, and painting.

[0058] The curing process employs a vacuum embedding method for irregularly shaped parts, with embedding materials including at least one of silica gel, silica powder, salt, quartz sand, steel balls, and ceramic slurry.

[0059] Specifically, when using quartz sand embedding, the surface of the continuous fiber reinforced composite is isolated with silicone rubber. The integrated frame of the drone is first kept at 65°C for 3 hours to allow the frame to initially cure. Then the temperature is raised to 140°C and kept for 4 hours to allow the integrated frame of the drone to fully cure.

[0060] Throughout the curing process, a vacuum pressure of 0.08MPa-0.095MPa is maintained.

[0061] This application also includes the following.

[0062] Based on equations Determine the calculated printing speed. Specifically, the calculated printing speed is the printing speed for arcs with different radii of curvature. The calculated printing speed is expressed in mm / min. The value represents the local radius of curvature, in mm. The equation is derived from linear fitting of experimental data, and the criterion is the limit speed at which pull-out occurs during the printing of circular arcs with different radii of curvature. The test results are as follows: the limit for R=5mm matching is v=100mm / min; the limit for R=10mm matching is v=200mm / min; the limit for R=25mm matching is v=500mm / min; the limit for R=50mm matching is v=800mm / min; and the limit for R=100mm matching is v=1500mm / min.

[0063] Specifically, in the 3D printing process of an integrated drone skeleton, different parts of the skeleton may have different geometries and degrees of curvature. For example, some connecting parts or sections with complex curved surfaces may have smaller local radii of curvature, meaning these parts are more severely curved; while some straighter sections have larger local radii of curvature. Calculating and adjusting the printing speed based on these different local radii of curvature is to ensure printing quality.

[0064] Determine whether the calculated printing speed is within the range of the actual printing speed.

[0065] If the calculated printing speed is within the range of the actual printing speed, select that calculated printing speed for printing the integrated frame of the drone.

[0066] If the calculated printing speed is not within the range of the actual printing speed, adjust the calculated printing speed.

[0067] When the calculated printing speed is less than 0.1 m / min, the actual minimum allowable printing speed of 0.1 m / min is used to print the integrated frame of the drone.

[0068] When the calculated printing speed is greater than 8m / min, the actual maximum allowable printing speed of 8m / min is used for printing the integrated frame of the drone.

[0069] This application also provides a continuous fiber reinforced composite unmanned aerial vehicle integrated skeleton printing device 600, such as... Figure 6 As shown, the device includes: an extraction module 601, a drawing module 602, a design module 603, a planning module 604, and a printing module 605.

[0070] The extraction module 601 is used to extract the aerodynamic shape profile of the UAV using 3D software.

[0071] The drawing module 602 is used to draw the integrated skeleton boundary of the UAV based on the aerodynamic profile and the minimum thickness requirements specified for the UAV skin.

[0072] Design module 603 is used to design the internal structure of the integrated UAV skeleton based on the drawn UAV skeleton boundary, combined with the anisotropic properties of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis.

[0073] The planning module 604 is used to plan the printing path and local feature processing strategy of the integrated UAV skeleton based on the boundary and internal structure of the integrated UAV skeleton, combined with the continuous fiber printing process and local feature bearing requirements. Specifically, the printing path is planned as a continuous path. Interpolation operations are performed before and after each feature point of the integrated UAV skeleton to set deceleration intervals, and the coordinates of the deceleration start point and deceleration end point corresponding to each deceleration interval are calculated.

[0074] The printing module 605 is used to print the integrated frame of the UAV using a continuous fiber printing device based on the printing path and local feature processing strategy, and to perform post-processing on the integrated frame of the UAV after printing.

[0075] Some modules in the apparatus described in this application can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc., that perform a specific task or implement a specific abstract data type. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0076] The apparatus or module described in the above embodiments can be implemented by a computer chip or physical entity, or by a product with a certain function. For ease of description, the above apparatus is described by dividing it into various modules according to their functions. When implementing the embodiments of this application, the functions of each module can be implemented in one or more software and / or hardware. Of course, a module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0077] The various embodiments described in this specification are presented in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. All or part of this application can be used in numerous general-purpose or special-purpose computer system environments or configurations.

[0078] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A method for printing an integrated skeleton of a continuous fiber reinforced composite unmanned aerial vehicle, characterized in that, include: Extract the aerodynamic shape profile of the UAV using 3D software; Based on the aerodynamic profile and the minimum thickness requirements specified for the UAV skin, draw the boundary of the integrated UAV skeleton. Based on the drawn boundary of the integrated UAV skeleton, combined with the anisotropic properties of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis, the internal structure of the integrated UAV skeleton is designed. Based on the boundary and internal structure of the integrated UAV skeleton, and combined with the continuous fiber printing process and local feature bearing requirements, the printing path and local feature processing strategy of the integrated UAV skeleton are planned. Among them, the printing path is planned as a continuous path, and interpolation operations are performed before and after each feature point of the integrated UAV skeleton to set deceleration intervals, and the deceleration start coordinates and deceleration end coordinates corresponding to each deceleration interval are calculated. Based on the printing path and local feature processing strategy, a continuous fiber printing device is used to print the integrated frame of the UAV. After printing, the integrated frame of the UAV is post-processed.

2. The method for printing an integrated skeleton of a continuous fiber reinforced composite UAV according to claim 1, characterized in that, Based on the drawn boundaries of the integrated UAV skeleton, combined with the anisotropic properties of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis, the internal structure of the integrated UAV skeleton is designed, including: The fiber material of the continuous fiber reinforced composite is at least one of carbon fiber, glass fiber, basalt fiber, and aramid fiber; the fiber specification range is [1K, 12K]. The matrix material of the continuous fiber reinforced composite is a thermosetting resin, including at least one of epoxy resin, phenolic resin, bismaleimide resin and polyimide resin; The fiber mass fraction of continuous fiber reinforced composites ranges from [35%, 70%], and the anisotropic properties of continuous fiber reinforced composites are assigned values ​​through measured performance. The stress conditions of the UAV are simplified by applying constraints to the lift changes during flight attitude transformation in the finite element simulation analysis software. The internal structure of the integrated frame of the UAV is designed based on the principle of evaluating the deformation amount through simulation and prioritizing straight lines in the printing path.

3. The method for printing an integrated skeleton of a continuous fiber-reinforced composite UAV according to claim 1, characterized in that, Interpolation operations are performed before and after each feature point of the integrated UAV skeleton to set deceleration intervals, and the coordinates of the deceleration start point and deceleration end point corresponding to each deceleration interval are calculated, including: The formula for calculating the coordinates of the deceleration starting point is: ； ； in, Let x be the x-coordinate of the deceleration starting point. An array to store the coordinates of feature points along the printing path, For array index variables, The x-coordinate of the feature point preceding the deceleration interval. This is the deceleration ratio. The x-coordinate of the feature point following the deceleration interval. The ordinate of the deceleration starting point. The ordinate of the feature point preceding the deceleration interval. This represents the ordinate of the next feature point after the deceleration interval; The formula for calculating the coordinates of the deceleration endpoint is: ； ； in, Let x be the x-coordinate of the deceleration endpoint. The vertical coordinate is the endpoint of the deceleration.

4. The method for printing an integrated skeleton of a continuous fiber reinforced composite UAV according to claim 3, characterized in that, The formula for calculating the deceleration ratio is: ;in, This is the deceleration ratio. To reduce deceleration distance, The characteristic length is denoted as .

5. The method for printing an integrated skeleton of a continuous fiber reinforced composite UAV according to claim 1, characterized in that, Continuous fiber printing processes include at least one of in-situ impregnation printing, prepreg printing, and prepreg impregnation printing; In the continuous fiber printing process, the nozzle orifice diameter ranges from [0.8mm to 3mm]; the actual printing speed ranges from [0.1m / min to 8m / min]; the printing layer height ranges from [0.2mm to 0.6mm]; the printing offset ranges from [0.8mm to 3.5mm]; the printing nozzle temperature ranges from [100℃ to 250℃]; the printing gas flow rate is from [10L / min to 25L / min]; and the printing ultraviolet wavelength range is from [320nm to 395nm].

6. The method for printing an integrated skeleton of a continuous fiber reinforced composite UAV according to claim 1, characterized in that, Local features include corners, intersections, curves, and cantilever structures; Local feature processing strategies include heat dissipation and rapid cooling strategy, filament dispersion and hot pressing strategy, variable speed strategy, pad support and variable posture printing strategy; Specifically, a rapid cooling strategy with heat dissipation pressure is used at corners; a filament dispersion and hot pressing strategy is used at intersections; a variable speed strategy is used at curves; and a pad support or variable posture printing strategy is used at cantilever structures.

7. The method for printing an integrated skeleton of a continuous fiber-reinforced composite UAV according to claim 1, characterized in that, The post-processing of the integrated UAV frame after printing includes: Post-processing includes curing, sanding, and painting. The curing process employs a vacuum embedding method for irregularly shaped parts, with embedding materials including at least one of silica gel, silica powder, salt, quartz sand, steel balls, and ceramic slurry. Throughout the curing process, a vacuum pressure of 0.08MPa-0.095MPa is maintained.

8. The method for printing an integrated skeleton of a continuous fiber reinforced composite UAV according to claim 1, characterized in that, Also includes: Based on equations Determine the calculated printing speed; where, For the calculated printing speed, The radius of curvature is the local radius of curvature. Determine whether the calculated printing speed is within the range of the actual printing speed; If the calculated printing speed is within the range of the actual printing speed, select the calculated printing speed for printing the integrated frame of the drone; If the calculated printing speed is not within the range of the actual printing speed, adjust the calculated printing speed. When the calculated printing speed is less than 0.1 m / min, the actual minimum allowable printing speed of 0.1 m / min is used to print the integrated frame of the drone. When the calculated printing speed is greater than 8m / min, the actual maximum allowable printing speed of 8m / min is used for printing the integrated frame of the drone.

9. A continuous fiber reinforced composite unmanned aerial vehicle (UAV) integrated skeleton printing device, characterized in that, include: The extraction module is used to extract the aerodynamic shape profile of the UAV using 3D software. The drawing module is used to draw the integrated skeleton boundary of the UAV based on the aerodynamic shape profile and the minimum thickness requirements specified for the UAV skin. The design module is used to design the internal structure of the integrated UAV skeleton based on the drawn UAV skeleton boundary, combined with the anisotropic properties of the continuous fiber reinforced composite and the stress conditions of the UAV obtained through simulation analysis. The planning module is used to plan the printing path and local feature processing strategy of the UAV integrated frame based on the boundary and internal structure of the UAV integrated frame, combined with the continuous fiber printing process and local feature bearing requirements. Among them, the printing path is planned as a continuous path, and interpolation operation is performed before and after each feature point of the UAV integrated frame to set the deceleration interval, and the deceleration start coordinates and deceleration end coordinates corresponding to each deceleration interval are calculated. The printing module is used to print the integrated frame of the UAV using a continuous fiber printing device based on the printing path and local feature processing strategy, and to perform post-processing on the integrated frame of the UAV after printing.

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