Composite material prefabricated body sewing forming method and system

Abstract

The invention provides a composite material prefabricated body sewing forming method and system, and relates to the technical field of advanced composite material manufacturing. According to the method, on the basis of joint cooperation of a mechanical arm, a modular stitching head and a control system, selection and area matching of stitching processes are completed by analyzing the local thickness, geometric morphology, curvature change and enhancement direction requirements of a composite prefabricated body, and different stitching processes are adopted in different areas of the same prefabricated body for cooperative stitching. In the forming process, the control system conducts unified planning and coordinated control on the motion trail of the mechanical arm, the action of the sewing head and sewing process parameters, and switching and accurate execution of the sewing process are achieved. The method can effectively meet the three-dimensional reinforced forming requirements of complex curved surfaces and special-shaped composite material preforms, improves sewing consistency, reliability and process flexibility, and is suitable for manufacturing preforms of high-performance composite material structures in the fields of aerospace and the like.

Description

Technical Field

[0001] This invention relates to the field of advanced composite material manufacturing technology, specifically to a method and system for stitching and forming composite material preforms. Background Technology

[0002] Composite materials, with their superior properties such as high specific strength, high specific modulus, high temperature resistance, ablation resistance, fatigue resistance, and designability, are widely used in aerospace, energy, and high-end manufacturing fields. To further improve the interlaminar properties, impact resistance, and overall structural integrity of composite components, three-dimensional stitching technology is now widely used for the molding and manufacturing of composite materials.

[0003] Existing three-dimensional stitching of composite materials mainly relies on manual operation or semi-automated equipment, resulting in low efficiency, limited precision, and unstable stitch quality. Furthermore, traditional stitching processes typically use a single stitching method, making it difficult to differentiate for complex curved structures or localized reinforcement needs. In the forming of highly complex components (such as aerospace rudder shafts, blades, and curved shells), the operation of the stitching head in curved or spatially confined areas is challenging, and the tension of the stitching thread and the needle force are difficult to control in real time, easily leading to structural defects or insufficient local performance. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a method for stitching and forming composite material preforms.

[0005] Technical solution: A method for stitching and forming composite material preforms, comprising the following steps:

[0006] S1. Select the required stitching process type for the composite preform, and set the corresponding stitch head type, stitch needle specification and stitch material. Fix the required stitch head to the robotic arm.

[0007] S2. Import the geometry of the composite material preform into the process planning software, and set the stitching area, stitch density, stitch spacing, stitching path, stitch tension, and stitching needle force.

[0008] S3. Input the suture path into the robotic arm control system, which converts it into the motion trajectory of the robotic arm connected to the suture head; the robotic arm drives the suture head to suture the composite material preform according to the motion trajectory.

[0009] S4. Select the next stitching process type required for the composite preform, and repeat steps S1 to S3 until the stitching of the composite preform is completed.

[0010] Specifically, the types of sewing techniques include tufting, loop stitch, and double needle stitch.

[0011] Preferably, step S3 further includes: using a robotic arm control system to perform closed-loop control and adaptive adjustment of suture tension, suture needle force, and needle position deviation.

[0012] Specifically, the robotic arm is a six-degree-of-freedom robotic arm, and its motion trajectory is a six-degree-of-freedom trajectory.

[0013] Specifically, the setting of the suture path includes: setting the incident angle and feed accuracy of the suture needle of the suture head according to the local curvature and space constraints of the composite material preform.

[0014] Specifically, select the corresponding stitching technique type.

[0015] Specifically, the structural characteristics of the local area include the thickness distribution, geometry, curvature variation, and spatial accessibility of the local area; the reinforcement requirements include enhancing the anti-delamination performance between layers, forming continuous suture paths, forming through-and-through or lock-knot suture structures, and the direction of suture reinforcement.

[0016] Specifically, the appropriate stitching process type is matched based on the structural characteristics of the local area and the reinforcement requirements. When the reinforcement requirement is to stitch in the direction of thickness, the tufting stitching process is selected; when the reinforcement requirement is to form a through-and-through or lock knot stitch structure, the loop stitching process or double needle stitching process is selected.

[0017] Specifically, the robotic arm control system includes a vision recognition unit and a force feedback unit. The vision recognition unit is used to acquire the surface geometric information of the composite material preform, and the force feedback unit is used to acquire the suture tension and suture needle force information. The robotic arm control system adjusts the robotic arm's motion trajectory and the suture needle feed speed of the suture head according to the surface geometric information of the composite material preform, the suture tension, and the suture needle force information.

[0018] The present invention also provides a composite material preform stitching system, comprising:

[0019] Process selection module: Used to select the type of stitching process required for the composite preform, and to set the corresponding stitch head type, stitch needle specification and stitch material, and to fix the required stitch head to the robotic arm;

[0020] Parameter setting module: Used to import the geometry of composite material preforms into the process planning software and set the stitching area, stitch density, stitch spacing, stitching path, suture tension, and suture needle force;

[0021] The suture execution module is used to input the suture path into the robotic arm control system, which converts it into the motion trajectory of the robotic arm connected to the suture head. The robotic arm drives the suture head to suture the composite material preform according to the motion trajectory.

[0022] Process switching module: Used to select the next stitching process type required for the composite preform. The process selection module, parameter setting module and stitching execution module are used in sequence until the stitching of the composite preform is completed.

[0023] Beneficial effects: Compared with the prior art, the significant effects of this invention are: This invention achieves high-precision automated three-dimensional stitching of composite material preforms through the collaboration of a stitching head and a multi-degree-of-freedom robotic arm, while supporting multiple stitching process combinations and local process switching, and can optimize the stitching structure for complex curved surfaces and local reinforcement needs; through the modular connection and precise control of the stitching head and robotic arm, the stability of the stitching action and the accuracy of line tension control are improved, and the stitching defect rate is reduced; through the overall modular design, this invention expands its application scope and can be used for intelligent forming of aerospace, energy and high-end composite material components, while improving stitching quality and production efficiency. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention.

[0025] Figure 2 This is a diagram of the robotic arm control system architecture of Embodiment 1 of the present invention. Detailed Implementation

[0026] A preferred embodiment of the present invention will be further described below with reference to the accompanying drawings.

[0027] Example 1

[0028] Please see Figure 1 As shown, this embodiment provides a method for stitching and forming a composite material preform, including the following steps:

[0029] S1. Select the required stitching process type for the composite preform, and set the corresponding stitch head type, stitch needle specification and stitch material. Fix the required stitch head to the robotic arm.

[0030] In this embodiment, the stitching processes include tufting, looper stitching, and double-needle stitching. For tufting, looper stitching, and double-needle stitching heads, after acquiring the geometric shape and local structural characteristics of the composite preform, the reinforcement requirements of different local areas are analyzed. The corresponding stitching process type is matched based on the local structural characteristics and reinforcement requirements. Local structural characteristics include local thickness distribution, local geometry, local curvature variation characteristics, and local spatial accessibility. Reinforcement requirements include enhancing interlayer delamination resistance, forming continuous stitching paths, forming through-and-through or lock-knot stitching structures, and the direction of stitch reinforcement. When a single stitching process cannot meet the requirements, a combination of multiple stitching processes is used. Depending on the actual operational needs, tufting is suitable for interlayer reinforcement in thick plate areas, complex curved surface areas, and areas accessible on one side; looper stitching is suitable for areas with varying thickness, curved transition areas, and structural parts with directional reinforcement requirements; double-needle stitching is suitable for regular planar areas, low curvature areas, and critical load-bearing areas with high requirements for lock-knot structures and continuous stitching paths.

[0031] The aforementioned suture head includes a thread-leading mechanism, a thread-hooking mechanism, a thread-picking mechanism, a transmission mechanism, and a tension control mechanism. All mechanisms are driven by the same servo motor and utilize synchronous belts, crank connecting rods, cams, bevel gears, and other mechanisms to achieve the thread introduction, hooking, picking, and placement actions. By precisely controlling the servo motor's speed and angle, the suture cycle can be accurately adjusted. Furthermore, through PLC-linked control with a robotic arm, high-precision control of the suture position, stitch length, and pitch can be achieved. By selecting a mature suture head solution from existing technologies, and connecting it to the robotic arm execution end as an overall module, as an example, the specific structure of the tufted suture head selected in this embodiment is exactly the same as the structure described in the Chinese invention patent "A pneumatic tufted suture robot and its suture method" with publication number CN120291293A; the specific structure of the curved needle suture head selected in this embodiment is exactly the same as the structure described in Feng Qiaoqiao's master's thesis "Design of single-sided curved needle suture head of composite material and study on mechanical properties of laminate" (DOI:10.27239 / d.cnki.gnhhu.2019.000790) published in 2019; the specific structure of the double needle suture head selected in this embodiment is exactly the same as the structure described in Gao Ziqiao et al.'s "Design of single-sided double needle double thread suture head and study on its motion trajectory" ([1] Gao Ziqiao, Dong Jiuzhi, Chen Yunjun, et al. Design and experimental verification of single-sided double needle double thread swing suture trajectory [J]. China Mechanical Engineering, 2024, The structure described in 35(01):102-108.DOI:10.3969 / j.issn.1004-132X.2024.01.010. is exactly the same. The specific structure of the above suture head will not be repeated here. It should be noted that all modularly designed suture heads can be applied to the technical solution of the present invention. The above suture heads are only examples and are not intended to limit the technical solution of the present invention.

[0032] S2. Import the geometry of the composite material preform into the process planning software, and set the stitching area, stitch density, stitch spacing, stitching path, stitch tension, and stitching needle force.

[0033] During the planning of the suture path, the incident angle and feed accuracy of the suture needle at the suture head are set according to the local curvature and space constraints of the composite preform.

[0034] S3. Input the suture path into the robotic arm control system, which converts it into the motion trajectory of the robotic arm connected to the suture head. The robotic arm drives the suture head to suture the composite material preform according to the motion trajectory.

[0035] In this embodiment, the robotic arm control system includes a vision recognition unit and a force feedback unit. The vision recognition unit is used to acquire the surface geometric information of the composite material preform, and the force feedback unit is used to acquire the suture tension and suture needle force information. The robotic arm control system adjusts the robotic arm movement trajectory and the suture needle feed speed of the suture head according to the surface geometric information of the composite material preform, the suture tension and the suture needle force information, so as to realize closed-loop adaptive control.

[0036] S4. Select the next stitching process type required for the composite preform, and repeat steps S1 to S3 until the stitching of the composite preform is completed.

[0037] The above method will be illustrated in a specific implementation scenario below:

[0038] For composite preforms where thickness reinforcement is the primary objective, tufting stitching is selected as the main stitching method. Based on the structural characteristics and reinforcement requirements of the composite preform, appropriate tufting heads, needle specifications, and suture materials are matched. The stitching area, stitch density, stitch length, and stitching path are set in the process planning software, and the suture tension and needle puncture force are parameterized.

[0039] The planned suture path is input into the robotic arm control system for six-degree-of-freedom trajectory planning. The six-degree-of-freedom robotic arm ensures the suture needle maintains a predetermined incident angle and feed accuracy in complex curved surfaces, achieving three-dimensional suture path tracking. The robotic arm drives the tufted suture head along the planned trajectory, completing the puncture, retraction, and suture feeding actions. The robotic arm control system monitors the suture needle position, suture tension, and needle force in real time, and achieves adaptive adjustment through closed-loop control.

[0040] After the tufting and sewing process is completed, if the composite preform has a large local curvature or needs to form an interlocking structure, it will automatically switch to curved needle sewing or double needle sewing to continue the sewing process, ensuring the continuity of the overall sewing reinforcement effect and the structural consistency.

[0041] Please refer to Figure 2 As shown, in this embodiment, the robotic arm control system adopts a single master station structure and a one-master-multiple-slave network control strategy. The PLC serves as the master station of the control system, serially connecting each servo motor system in the stitching head via an EtherCAT fieldbus, and communicating with the robotic arm and teach pendant via a Profinet bus. This connects the various discrete I / Os and intelligent devices in the system together. The PLC, acting as the network communication hub, manages the data exchange between the various devices through bus communication, achieving coordinated control of the overall system.

[0042] The working process of the robotic arm control system includes the following steps:

[0043] 1. Input process parameters such as the geometry of the composite preform, stitching area, stitch density, stitch length, stitch path, and suture tension into the teach pendant. The PLC control system receives the process parameters and generates the motion trajectory of the robotic arm and stitching head.

[0044] 2. The PLC control system sends motion commands to the robotic arm control console via EtherCAT. The robotic arm moves along the planned trajectory to ensure the incident angle and feed accuracy of the suture needle in complex curved areas.

[0045] 3. The PLC control system uses EtherCAT to control the suture head servo driver, achieving synchronous movement of the suture needle, hook needle, and thread hook, thereby completing the actions of suture introduction, suture loop hooking, and suture placement. During suturing, the PLC control system acquires the suture needle force, suture tension, and needle position deviation in real time, and adjusts the movements of the robotic arm and suture head through closed-loop control to ensure suture quality and structural integrity.

[0046] 4. The PLC control system sends real-time data of the suturing process to the teach pendant via Profinet, allowing operators to intuitively monitor the suturing status and adjust process parameters or pause the operation as needed.

[0047] Example 2

[0048] This embodiment provides a composite material preform stitching system corresponding to the composite material preform stitching method described in Embodiment 1, comprising:

[0049] Process selection module: Used to select the type of stitching process required for the composite preform, and to set the corresponding stitch head type, stitch needle specification and stitch material, and to fix the required stitch head to the robotic arm;

[0050] Parameter setting module: Used to import the geometry of composite material preforms into the process planning software and set the stitching area, stitch density, stitch spacing, stitching path, suture tension, and suture needle force;

[0051] The suture execution module is used to input the suture path into the robotic arm control system, which converts it into the motion trajectory of the robotic arm connected to the suture head. The robotic arm drives the suture head to suture the composite material preform according to the motion trajectory.

[0052] Process switching module: Used to select the next stitching process type required for the composite preform. The process selection module, parameter setting module and stitching execution module are used in sequence until the stitching of the composite preform is completed.

Claims

1. A method for stitching and forming a composite material preform, characterized in that, Includes the following steps: S1. Select the required stitching process type for the composite preform, and set the corresponding stitch head type, stitch needle specification and stitch material. Fix the required stitch head to the robotic arm. S2. Import the geometry of the composite material preform into the process planning software, and set the stitching area, stitch density, stitch spacing, stitching path, stitch tension, and stitching needle force. S3. Input the suture path into the robotic arm control system, which converts it into the motion trajectory of the robotic arm connected to the suture head. The robotic arm drives the suture head to suture the composite material preform according to the motion trajectory. S4. Select the next stitching process type required for the composite preform, and repeat steps S1 to S3 until the stitching of the composite preform is completed.

2. The method for stitching and forming composite material preforms according to claim 1, characterized in that: The stitching techniques include tufting, loop stitching, and double needle stitching.

3. The method for stitching and forming composite material preforms according to claim 1, characterized in that, Step S3 also includes: using a robotic arm control system to perform closed-loop control and adaptive adjustment of suture tension, suture needle force, and needle position deviation.

4. The method for stitching and forming composite material preforms according to claim 1, characterized in that: The robotic arm is a six-degree-of-freedom robotic arm, and the motion trajectory is a six-degree-of-freedom trajectory.

5. The method for stitching and forming composite material preforms according to claim 1, characterized in that: The setting of the suture path includes: setting the incident angle and feed accuracy of the suture needle of the suture head according to the local curvature and space constraints of the composite material preform.

6. The method for stitching and forming composite material preforms according to claim 2, characterized in that: The selection of the required stitching process type for the composite material preform includes: obtaining the geometric shape and local structural feature information of the composite material preform, analyzing the reinforcement requirements of different local areas, and matching the corresponding stitching process type according to the local structural feature information and reinforcement requirements.

7. The method for stitching and forming composite material preforms according to claim 6, characterized in that: The local structural feature information includes local thickness distribution, local geometry, local curvature variation characteristics, and local spatial accessibility; the reinforcement requirements include enhancing interlayer anti-delamination performance, forming continuous suture paths, forming through-and-through or lock-knot suture structures, and the direction of suture reinforcement.

8. The method for stitching and forming composite material preforms according to claim 7, characterized in that: The matching of the appropriate suturing process type based on the local area structural feature information and reinforcement requirements includes: when the reinforcement requirement is to suturing in the direction of thickness, tufting suturing process is selected; when the reinforcement requirement is to form a through-and-through or lock knot suturing structure, loop needle suturing process or double needle suturing process is selected.

9. The method for stitching and forming composite material preforms according to claim 1, characterized in that: The robotic arm control system includes a vision recognition unit and a force feedback unit. The vision recognition unit is used to acquire the surface geometric information of the composite material preform, and the force feedback unit is used to acquire the suture tension and suture needle force information. The robotic arm control system adjusts the robotic arm movement trajectory and the suture needle feed speed of the suture head according to the surface geometric information of the composite material preform, the suture tension and the suture needle force information.

10. A composite material preform stitching system, characterized in that, include: Process selection module: Used to select the type of stitching process required for the composite preform, and to set the corresponding stitch head type, stitch needle specification and stitch material, and to fix the required stitch head to the robotic arm; Parameter setting module: Used to import the geometry of composite material preforms into the process planning software and set the stitching area, stitch density, stitch spacing, stitching path, suture tension, and suture needle force; The suture execution module is used to input the suture path into the robotic arm control system, which converts it into the motion trajectory of the robotic arm connected to the suture head. The robotic arm drives the suture head to suture the composite material preform according to the motion trajectory. Process switching module: Used to select the next stitching process type required for the composite preform. The process selection module, parameter setting module and stitching execution module are used in sequence until the stitching of the composite preform is completed.

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