A method and device for space winding forming of a continuous fiber reinforced composite quadrotor unmanned aerial vehicle framework

Abstract

A kind of continuous fiber reinforced composite four-rotor unmanned aerial vehicle framework space winding forming method and device, it is related to continuous fiber reinforced composite forming technical field.The forming method of the present application includes: framework partition and fiber section bearing design;In mold bottom plate arrangement detachable release model anchor point and reserved type anchor point;The anchor point is abstracted as the vertex of topological graph, fiber section edge constructs fiber topological graph;Solve the continuous Euler winding path of least broken yarn;Through six-axis mechanical arm cooperation on-line gelatinization, variable tension control is completed carbon fiber space winding, after completing all winding, after heat curing, release to obtain integrated continuous fiber composite unmanned aerial vehicle framework.The present application adopts continuous fiber space winding mode, and forms the center bearing area, arm and motor installation area into an integrated form, reduces the connecting piece and mechanical connection joint in traditional assembled framework, reduces the risk of weak, loose or failure of connecting part.

Description

Technical Field

[0001] This invention relates to the field of intelligent manufacturing equipment technology, specifically to a method and apparatus for spatial winding molding of a continuous fiber reinforced composite quadcopter drone skeleton. This method and apparatus are used for continuous fiber reinforced composite material winding molding, industrial robot processing, and drone structure manufacturing. Background Technology

[0002] A typical quadcopter drone frame includes a central load-bearing area, multiple circumferentially distributed arms, and motor mounting areas at the ends of the arms. Existing frames are mostly fabricated from sheet metal, profiles, or separate composite material components, which are then assembled using bolts, rivets, adhesive joints, or connectors. This method requires numerous connectors and localized reinforcements, increasing structural weight and assembly steps. Furthermore, the load must be transferred through multiple material interfaces and discrete connection points, making these connection areas prone to stress concentration, loosening, or damage, thus becoming weak points in the overall load-bearing capacity and operational reliability of the frame.

[0003] Continuous fiber reinforced composites possess advantages such as high specific strength and specific stiffness, and customizable fiber orientation, making them suitable for lightweight load-bearing structures in unmanned aerial vehicles (UAVs). However, conventional laminate cutting and assembly methods still retain many connection interfaces, making it difficult to fully utilize the advantages of continuous fiber load transfer along the load direction. Furthermore, conventional continuous fiber printing methods typically rely on layer-by-layer deposition and nozzle compaction, which limits the continuous forming of spatial rods spanning nodes at different heights, closed or intersecting fiber bundles, and integrated boom structures.

[0004] Coreless space winding allows resin-impregnated continuous fibers to directly span between discrete anchor points and form load-bearing members, eliminating the need for a solid mandrel perfectly matching the shape. However, the UAV frame contains multiple arms, a central intersection area, and a motor mounting area, resulting in a large number of fiber segments with complex continuity. Relying solely on manual experience to arrange the winding sequence can easily lead to problems such as missing fiber segments, repeated idle strokes, interference from robotic arm movements, and frequent yarn breaks and re-threading. Furthermore, the path length, axial angle, and anchor point wrapping state constantly change during the winding process. Using constant tension can easily cause fiber slippage or tension damage at sharp turning points, while fiber loosening may occur in long spans.

[0005] Therefore, there is a need for a forming method and apparatus that can combine the structural design of a quadcopter drone frame, the configuration of anchor tooling, the solution of the winding sequence, the spatial motion of the robotic arm, online impregnation, variable tension control, thermosetting and demolding processes, so as to reduce the split connection and structural quality of the frame, and improve the continuity, feasibility and forming consistency of the complex spatial winding process. Summary of the Invention

[0006] This invention addresses the following problems existing in traditional quadrotor drone frames: weak connection points and numerous connectors due to split manufacturing; difficulty in determining the winding sequence during complex frame spatial winding, numerous yarn breaks and re-winding operations, and fiber tension fluctuations; as well as the large mass of the frame and structure. Therefore, it proposes a method and apparatus for spatial winding forming of an integrated quadrotor drone frame, using a detachable anchor point array as winding support, a multi-axis mechanical device based on a six-axis robotic arm to perform continuous fiber spatial winding, and determining the winding sequence through graph theory Euler path solving.

[0007] The technical solution adopted by the present invention to solve the above problems is as follows: In a first aspect, the present invention provides a method for spatial winding molding of a continuous fiber reinforced composite quadrotor drone frame, comprising the following steps: Step 1: Determine the shape of the central load-bearing area, the four arm areas, and the four motor mounting areas. Set the fiber segments to be formed between the above areas, and determine the number of times each fiber segment is repeatedly wound according to the local load-bearing requirements. Step 2: Arrange multiple anchor points on the base plate according to the endpoints and turning positions of the fiber segments. The anchor points are detachably connected to the base plate. Step 3: Abstract the anchor points as vertices in the topological graph structure, and abstract the fiber segments that need to be formed between adjacent anchor points as edges in the topological graph structure; for fiber segments that need to be repeatedly wound, set them as multiple edges or assign them a number of times to be repeatedly traversed, forming a graph structure that represents the fiber topological relationship of the UAV skeleton. Step 4: Determine whether the graph structure satisfies the Euler path condition. If it does, solve the Euler path that covers all the designed fiber segments in one go, and convert the resulting vertex sequence into the anchor point access order. If the conditions are not met, the graph is decomposed, some fiber segments are allowed to be traversed repeatedly, or the graph is divided into multiple continuously winding sub-paths to ensure that all designed fiber segments are covered, and the number of continuous sub-paths is minimized. Step 5: Generate the motion trajectory of the six-axis robotic arm according to the anchor point access sequence, so that the end yarn guiding mechanism sequentially completes the actions of approaching the anchor point, passing around the anchor point, leaving the anchor point, and moving to the next anchor point, and checks the interference between the robotic arm and the base plate, anchor points, and wound fibers. Step 6: The carbon fiber is drawn out from the yarn supply assembly, impregnated with thermosetting epoxy resin by the online impregnation assembly, and then pulled by the yarn guiding mechanism at the end of the robotic arm. It passes around each anchor point in sequence according to the obtained anchor point access order, so that the fiber is tensioned between adjacent anchor points to form a spatial fiber segment, and cross-over or repeatedly wound in the central area, the root of the robotic arm and the motor mounting area. Step 7: Detect fiber tension data in real time using a tension sensor, and adjust the yarn feeding resistance or unwinding speed by a tension adjustment mechanism according to the movement state and path segment of the robotic arm. Step 8: After completing all the winding, heat-curing is performed while the skeleton is still positioned by the anchor points. After curing and cooling, the connection between the anchor points and the base plate is released, and the cured skeleton is separated from the base plate.

[0008] Furthermore, in step 2, the anchor points include demolding anchor points and retention anchor points. The demolding anchor points are removed from the skeleton after curing; the retention anchor points are located at the end of the arm and are retained with the skeleton after curing and used for installing motors.

[0009] Furthermore, in step 4, fiber segments that are allowed to be traversed repeatedly are preferentially located in the central area, at the root of the arm, or in the motor mounting area, in order to balance path continuity and local reinforcement.

[0010] Furthermore, in step 7, with 10N as the reference tension, a tension suitable for fiber tension is maintained during the straight crossing section, and the target tension is adjusted when approaching the anchor point, making a sharp turn, and crossing the already wrapped fiber, in order to reduce fiber loosening, slippage, or tension loss.

[0011] Furthermore, in step 8, the thermosetting conditions are: curing temperature of 100 ℃; curing time of 2 hours.

[0012] Furthermore, in step 8, according to the method for spatial winding molding of a continuous fiber reinforced composite quadcopter drone skeleton as described in claim 1, the demolding anchor points are extracted and separated from the inside of the skeleton, and the entire drone skeleton with retained anchor points is taken out from the base plate.

[0013] Secondly, the present invention provides a continuous fiber reinforced composite quadcopter drone skeleton spatial winding molding device, the device being used to implement the above-mentioned molding method, the device comprising a tooling assembly, a yarn supply and online impregnation assembly, a tension detection and adjustment assembly, and a multi-axis motion assembly, characterized in that the tooling assembly comprises: The base plate is used to determine the datum for skeleton forming. And multiple anchor points distributed on the base plate, which are detachably connected to the base plate for positioning, turning and wrapping the fibers.

[0014] Furthermore, the anchor points include demolding anchor points and retained anchor points. The retained anchor points are arranged at the four corner motor assembly positions of the base plate and are retained with the finished frame after curing. The demolding anchor points are arranged in the central bearing area and the transition area of ​​the arm in the middle of the base plate and can be disassembled and separated after curing.

[0015] Furthermore, each of the anchor points is provided with a guide groove or a limiting structure, and is detachably connected to the base plate by bolts.

[0016] Thirdly, the present invention provides a continuous fiber reinforced composite quadcopter drone frame, which is formed using the above-mentioned method or apparatus.

[0017] The beneficial effects of this invention are: 1. This invention uses a continuous fiber spatial winding method to integrate the central load-bearing area, the arm and the motor mounting area into one piece, reducing the number of connectors and mechanical joints in the traditional assembled frame, and reducing the risk of weak, loose or failed connection parts.

[0018] 2. This invention fully utilizes the characteristic of continuous fibers arranged along the load-bearing direction, which reduces the number of redundant materials and parts while meeting the load-bearing requirements of the skeleton. This helps to reduce the weight of the quadcopter drone skeleton, making it lighter and improving the specific strength and specific stiffness of the structure. 3. In this invention, the anchor point and the fiber segment to be wound are abstracted as nodes and edges in a graph structure, respectively, and the continuous winding sequence is solved by Euler path. When it is not possible to complete the entire winding with a single fiber, the number of yarn breaks and re-threading can be reduced as much as possible, thereby improving fiber continuity and forming efficiency.

[0019] 4. This invention uses a six-axis robotic arm for multi-axis collaborative winding, combined with online impregnation and variable tension control, to enable the fibers to be stably laid along a predetermined path, which helps to improve the consistency of fiber position, impregnation degree and winding quality.

[0020] 5. The present invention uses detachable anchor points and base plate to form a forming device. After curing, the connection between the anchor points and the base plate can be released, which facilitates the overall demolding of the frame. Some anchor points can be retained with the frame and directly used as motor mounting parts, reducing subsequent assembly processes and additional connection structures. 6. This invention changes the skeleton size, configuration and local reinforcement by adjusting the position and number of anchor points, fiber path and number of repeated windings, and has good structural adaptability and manufacturing flexibility. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the tooling assembly of the present invention.

[0022] Figure 2 This is a photograph of the skeleton of the present invention after winding and curing, and before demolding.

[0023] In the diagram: 1-base plate; 2-functional anchor point; 3-reserved functional anchor point; 4-fiber guide point; 5-fiber skeleton. Detailed Implementation

[0024] Specific Implementation Method 1: This implementation method proposes a method for spatial winding molding of a continuous fiber reinforced composite quadcopter drone frame, including the following steps: S1 skeleton and fiber segment design: Based on the overall dimensions of the quadcopter UAV, the installation space of the central equipment, the position of the motors, and the load-bearing requirements, determine the shape of the central load-bearing area, the four arms, and the four motor installation areas; set the fiber segments to be formed between the above areas, and determine the number of times each fiber segment is repeatedly wound according to the local load-bearing requirements.

[0025] S2 Anchor Point Layout: Multiple anchor points are arranged on the base plate according to the endpoints and turning positions of the fiber segments. The anchor points are detachably connected to the base plate by bolts, including release anchor points that are removed from the skeleton after curing, and retain anchor points located at the ends of the arm that are retained with the skeleton after curing and used for motor installation.

[0026] S3 Establishes a graph structure: Anchor points are abstracted as vertices, and the fiber segments that need to be formed between adjacent anchor points are abstracted as edges. For fiber segments that need to be repeatedly wound, they can be set as multiple edges or assigned a number of repetitions, thereby forming a graph structure that represents the fiber topology of the UAV skeleton.

[0027] S4 Solving the winding sequence: Determine if the graph structure satisfies the Eulerian path condition. If it does, solve for an Eulerian path that covers all designed fiber segments in one step, and convert the resulting vertex sequence into an anchor point access order. If it does not satisfy the condition, decompose the graph, allow some fiber segments to be traversed repeatedly, or divide the graph into multiple continuously winding sub-paths to ensure that all designed fiber segments are covered, prioritizing the minimization of the number of continuous sub-paths to reduce yarn breaks and re-threading. Fiber segments that can be traversed repeatedly can be preferentially located in the central area, at the root of the machine arm, or in the motor mounting area to balance path continuity and local reinforcement.

[0028] S5 trajectory generation: The motion trajectory of the six-axis robotic arm is generated according to the anchor point access sequence, so that the end yarn guiding mechanism sequentially completes the actions of approaching the anchor point, passing around the anchor point, leaving the anchor point, and moving to the next anchor point, and checks the interference between the robotic arm and the base plate, anchor points, and wound fibers.

[0029] S6 Online Impregnation and Space Wrapping: Carbon fibers are drawn from the yarn supply assembly, impregnated with thermosetting epoxy resin by the online impregnation assembly, and then pulled by the yarn guiding mechanism at the end of the robotic arm, sequentially winding around each anchor point according to the determined winding sequence. The fibers are tensioned between adjacent anchor points to form spatial fiber segments, and cross-over or repeatedly wound in the central area, at the root of the robotic arm, and in the motor mounting area.

[0030] S7 Variable Tension Control: Tension sensors detect fiber tension in real time, and the tension adjustment mechanism adjusts the yarn feeding resistance or unwinding speed according to the movement state and path section of the robotic arm. In actual processes, a reference tension of approximately 10 N is used; a suitable tension for fiber tension is maintained in straight crossing sections, and the target tension is adjusted when approaching the anchor point, making sharp turns, or crossing already wound fibers to reduce slack, slippage, or over-tension damage.

[0031] S8 thermosetting and demolding: After all the wrapping is completed, heat curing is performed while the skeleton is still positioned by the anchor points. The current implementation conditions are approximately 100 °C for about 2 hours of curing, but the specific conditions can be adjusted according to the resin system. After curing and cooling, the bolt connections between the anchor points and the base plate are released, and the retained anchor points are removed from the base plate along with the skeleton and left in the skeleton.

[0032] Specific Implementation Method Two: This implementation method proposes a continuous fiber reinforced composite quadrotor drone skeleton spatial winding molding device for implementing the molding method described in Specific Implementation Method One. The device includes: The tooling assembly includes a base plate 1 and multiple anchor points distributed on the base plate. The base plate 1 is used to determine the framework forming reference; the anchor points are used for fiber positioning, orientation, and wrapping. The anchor points include demolding anchor points and retention anchor points. The retention anchor points are arranged at the four corner motor assembly positions of the base plate and are retained with the finished framework after curing. The demolding anchor points are arranged in the central bearing area and the transition area of ​​the machine arm in the middle of the base plate and can be disassembled and separated after curing.

[0033] In this embodiment, a total of 20 anchor points are arranged on the mold base plate 1. Among them, four functional anchor points 2 (retained anchor points) are arranged at the four corners of the mold base plate 1, serving as the forming points for the UAV motor mounting base. After curing, they are retained integrally with the UAV frame. The remaining 16 anchor points are all demolding anchor points. Among them, 12 are fiber-guided anchor points 3, which are concentrated in the central bearing area of ​​the mold base plate 1 and are used to form the skeleton structure of the drone main control, battery and ESC installation area. The other four are reserved functional anchor points 2, located in the transition area of ​​the arm and set inside the functional anchor point 1.

[0034] Preferably, each anchor point can be equipped with a guide groove or a limiting structure, and is connected to the base plate by bolts so that it can be released after curing. Connection. The base plate is equipped with positioning holes or mounting slots that mate with the anchor points. The anchor point positions can be adjusted according to the different sizes of the drone frame.

[0035] The yarn feeding and online impregnation assembly is used to continuously release carbon fibers; the online impregnation assembly is located between the fiber roll and the end of the robotic arm to impregnate the fibers with thermosetting epoxy resin before winding and to control or remove excess resin.

[0036] The tension detection and adjustment component includes a tension sensor installed on the yarn supply path and an modulated or active unwinding mechanism, used to detect the actual tension and change the fiber supply state according to control commands to achieve variable tension control during the winding process.

[0037] A multi-axis motion assembly includes a six-axis robotic arm and a yarn guiding mechanism at its end; it may also include a turntable or moving shaft that cooperates with the robotic arm. The end-effector yarn guiding mechanism is used to accurately guide the sizing fibers to the corresponding anchor points and control the direction of the fibers entering and leaving the anchor points.

[0038] The control component is used to receive skeleton geometry and graph structure information to complete the Euler path or multiple continuous sub-paths.

[0039] Specific Implementation Method 3: This implementation method proposes a continuous fiber reinforced composite quadcopter drone frame, which is formed using the method described in Implementation Method 1 or the apparatus described in Implementation Method 2. The frame includes a central load-bearing area, arms extending in four directions from the central load-bearing area, and motor mounting areas located at the ends of each arm. The central load-bearing area and the arms are formed by multiple continuous fiber bundles crossing, overlapping, and being cured with resin. At least some of the continuous fiber bundles extend from one arm or motor mounting area to the central load-bearing area and continue to another arm or motor mounting area, thereby forming a continuous load transfer path between different functional areas.

[0040] The arm end features anchor points that are retained with the frame. These anchor points serve as guides and anchors for the fibers during winding and as motor mounting components after curing. The retained anchor points have mounting structures for bolting to the base plate and for securing the UAV motors. The central area of ​​the frame, the arm root, and the motor mounting area can be locally thickened by increasing the number of repetitions of the corresponding fiber segments.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A method for spatial winding molding of a continuous fiber reinforced composite quadrotor drone skeleton, characterized in that, The molding method includes the following steps: Step 1: Determine the shape of the central load-bearing area, the four arm areas, and the four motor mounting areas. Set the fiber segments to be formed between the above areas, and determine the number of times each fiber segment is repeatedly wound according to the local load-bearing requirements. Step 2: Arrange multiple anchor points on the base plate according to the endpoints and turning positions of the fiber segments. The anchor points are detachably connected to the base plate. Step 3: Abstract the anchor points as vertices in the topological graph structure, and abstract the fiber segments that need to be formed between adjacent anchor points as edges in the topological graph structure; for fiber segments that need to be repeatedly wound, set them as multiple edges or assign them a number of times to be repeatedly traversed, forming a graph structure that represents the fiber topological relationship of the UAV skeleton. Step 4: Determine whether the graph structure satisfies the Euler path condition. If it does, solve the Euler path that covers all the designed fiber segments in one go, and convert the resulting vertex sequence into the anchor point access order. If the conditions are not met, the graph is decomposed, some fiber segments are allowed to be traversed repeatedly, or the graph is divided into multiple continuously winding sub-paths to ensure that all designed fiber segments are covered, and the number of continuous sub-paths is minimized. Step 5: Generate the motion trajectory of the six-axis robotic arm according to the anchor point access sequence, so that the end yarn guiding mechanism sequentially completes the actions of approaching the anchor point, passing around the anchor point, leaving the anchor point, and moving to the next anchor point, and checks the interference between the robotic arm and the base plate, anchor points, and wound fibers. Step 6: The carbon fiber is drawn out from the yarn supply assembly, impregnated with thermosetting epoxy resin by the online impregnation assembly, and then pulled by the yarn guiding mechanism at the end of the robotic arm. It passes around each anchor point in sequence according to the obtained anchor point access order, so that the fiber is tensioned between adjacent anchor points to form a spatial fiber segment, and cross-over or repeatedly wound in the central area, the root of the robotic arm and the motor mounting area. Step 7: Detect fiber tension data in real time using a tension sensor, and adjust the yarn feeding resistance or unwinding speed by a tension adjustment mechanism according to the movement state and path segment of the robotic arm. Step 8: After completing all the winding, heat-curing is performed while the skeleton is still positioned by the anchor points. After curing and cooling, the connection between the anchor points and the base plate is released, and the cured skeleton is separated from the base plate.

2. The method for spatial winding molding of a continuous fiber reinforced composite quadrotor UAV skeleton according to claim 1, characterized in that, In step 2, the anchor points include demolding anchor points and retention anchor points. The demolding anchor points are removed from the skeleton after curing. The retention anchor points are located at the end of the arm and are retained with the skeleton after curing for use in installing motors.

3. The method for spatial winding molding of a continuous fiber reinforced composite quadrotor UAV skeleton according to claim 2, characterized in that, In step 4, fiber segments that are allowed to be traversed repeatedly are preferentially placed in the central area, at the root of the arm, or in the motor mounting area to balance path continuity and local reinforcement.

4. The method for spatial winding molding of a continuous fiber reinforced composite quadrotor drone skeleton according to claim 3, characterized in that, In step 7, with 10N as the reference tension, maintain a tension suitable for fiber tension during the straight crossing section, and adjust the target tension when approaching the anchor point, making a sharp turn, or crossing the already wrapped fiber to reduce fiber loosening, slippage, or tension loss.

5. The method for spatial winding molding of a continuous fiber reinforced composite quadrotor UAV skeleton according to claim 4, characterized in that, In step 8, the thermosetting conditions are: curing temperature of 100 ℃ and curing time of 2 hours.

6. The method for spatial winding molding of a continuous fiber reinforced composite quadrotor drone skeleton according to claim 5, characterized in that, In step 8, according to the method for spatial winding molding of a continuous fiber reinforced composite quadcopter drone skeleton as described in claim 1, the demolding anchor points are extracted and separated from the inside of the skeleton, and the entire drone skeleton with retained anchor points is taken out from the base plate.

7. A continuous fiber reinforced composite quadrotor drone skeleton spatial winding molding device, comprising a tooling assembly, a yarn supply and online impregnation assembly, a tension detection and adjustment assembly, and a multi-axis motion assembly, characterized in that, The apparatus is used to implement the molding method according to any one of claims 1-6, wherein the tooling assembly includes: The base plate is used to determine the datum for skeleton forming. And multiple anchor points distributed on the base plate, which are detachably connected to the base plate for positioning, turning and wrapping the fibers.

8. The continuous fiber reinforced composite quadrotor drone skeleton space winding molding device according to claim 7, characterized in that, The anchor points include demolding anchor points and retainable anchor points. The retainable anchor points are arranged at the four corner motor assembly positions of the base plate and are retained with the finished frame after curing. The demolding anchor points are arranged in the central bearing area and the transition area of ​​the arm in the middle of the base plate and can be disassembled and separated after curing.

9. The continuous fiber reinforced composite quadrotor drone skeleton space winding molding device according to claim 8, characterized in that, Each anchor point is provided with a guide groove or limiting structure and is detachably connected to the base plate by bolts.

10. A continuous fiber reinforced composite quadcopter drone frame, characterized in that, It is formed using the method described in any one of claims 1-6 or the apparatus described in any one of claims 7-8.

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