Automatic laying and forming process for carbon fiber fully-wound gas cylinder end socket reinforcing ring

Abstract

The invention discloses an automatic laying and forming process for a reinforcing ring of a carbon fiber fully-wound gas cylinder end socket, and relates to the technical field of carbon fiber wound gas cylinders. Technological parameters are simulated and optimized; the laying line type is imported into software to plan the motion track of the robot; carbon fiber prepreg is adopted, single-layer prepreg laying is conducted between every two spiral layers of the gas cylinder according to the optimal process parameters, and the laminating state of the prepreg is monitored in real time. Full-automatic precise laying can be achieved, and the production efficiency and consistency are improved; the material utilization rate is improved; the manufacturing cost is reduced; the laying wrinkle defect is eliminated, and the gas cylinder bearing safety is improved; process parameters are quantified and optimized, and the performance of the carbon fibers is fully released.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber wound gas cylinder technology, and more specifically, to an automatic laying and forming process for a carbon fiber fully wound gas cylinder end cap reinforcing ring. Background Technology

[0002] Carbon fiber fully wound gas cylinders are widely used in hydrogen energy storage and transportation, aerospace, and special equipment due to their advantages such as lightweight, high strength, and corrosion resistance. Among these applications, the cylinder head, as a critical component connecting the cylinder body and the cylinder opening, is subject to significant curvature changes near the pole holes and shoulders due to the characteristics of the winding process. This can easily lead to stress concentration under long-term internal pressure, making it a weak point in the cylinder structure. To improve the load-bearing capacity and service safety of the cylinder head, the industry has gradually developed cylinder head reinforcement technologies. From early manual laying of carbon fiber cloth to semi-automated fiber winding reinforcement, and then to the automated laying technology explored in recent years, the core development direction has always revolved around "adapting to the fully wound process, reducing material redundancy, improving reinforcement accuracy, and ensuring batch consistency" to meet the requirements of carbon fiber fully wound gas cylinders for "high pressure rating, long service life, and low manufacturing cost."

[0003] Currently, there are three main reinforcement processes for carbon fiber fully wound gas cylinder heads: **Laying Reinforcement Process:** This involves manually attaching non-woven carbon fiber fabric or carbon cloth directly to the winding layers or outer layers of the gas cylinder head, achieving reinforcement through localized material layering. The core principle is localized winding reinforcement: during the full winding of the gas cylinder fiber, the thickness of the carbon fiber material is locally increased to offset the load in areas of stress concentration in the head, adapting to the localized reinforcement needs of fully wound gas cylinders. **Winding Reinforcement Process:** After completing one longitudinal winding cycle, the fiber section is cut, retaining the fiber at both ends of the head area as a reinforcement layer. A subsequent derivative is the enlarged-hole winding reinforcement process, which reduces redundant reinforcement mass by changing the size of the front and rear end holes. The core principle is utilizing the continuity of the gas cylinder full winding equipment to ensure that the reinforcement layer and the main winding layer of the gas cylinder are formed synchronously, improving interlayer bonding and adapting to the integrated requirements of the full winding process. End Cap Reinforcement Process: Carbon fiber is woven or laid into an "end cap" that matches the shape of the gas cylinder end cap. The end cap is then fitted over the cylinder during the full winding process and impregnated with adhesive for curing, achieving structural reinforcement. End caps woven with a specific longitudinal-to-circular ratio reduce reinforcement weight compared to lay-up reinforcement, thus reducing overall cylinder redundancy. The core principle is to achieve overall reinforcement of the gas cylinder end cap through pre-formed end caps, reducing localized defects and meeting the strength requirements of high-pressure gas cylinders.

[0004] However, the above three processes have the following problems: The reinforcement process relies on manual operation, which is greatly affected by human factors (such as uneven laying pressure, angle deviation, and interlayer air bubbles). The reinforcement accuracy is difficult to control (the consistency error of carbon fiber direction is ≥5°), which cannot meet the stringent requirements of carbon fiber fully wound gas cylinders for interlayer accuracy. In addition, manual operation is inefficient (reinforcement time for a single cylinder is ≥2 hours), making it difficult to adapt to mass production. Although variable angle laying can be achieved through laying equipment, a high-precision automated system needs to be built, resulting in high process costs and the technology is not yet perfect.

[0005] Winding reinforcement process: inherent material waste exists (cutting the fiber section of the cylinder to form the reinforcement layer, material utilization rate ≤80%), especially for carbon fiber fully wound gas cylinders with an aspect ratio >3, the hole expansion reinforcement takes longer (the winding time per cylinder increases by 30%) and the material waste is more serious; the hole expansion process lacks theoretical guidance, if the hole expansion is too small, the improvement of fiber accumulation in the end cap is not obvious, if the hole expansion is too large, the fiber continuity is poor, resulting in a decrease in the local strength of the gas cylinder end cap; and the fiber distribution and overall strength of the gas cylinder after hole expansion need to be verified by a large number of experiments, resulting in high research and development costs.

[0006] Reinforcement process for end caps: Poor fit between the fully wound surface of the gas cylinder and the end cap surface (gap ≥ 0.2 mm) severely affects the interlayer bonding strength (interlayer shear strength decreases by 15%~20%); Conventional automatic filament placement equipment has a large filament placement head size (diameter ≥ 150 mm) and complex structure, which is only suitable for large curvature surfaces such as the gas cylinder body, and cannot adapt to small curvature areas (curvature radius ≤ 50 mm) near the end cap pole hole, which is prone to equipment interference and leads to placement interruption.

[0007] Common defects: Existing processes have not solved the problem of wrinkling of carbon fiber prepreg in the cylinder head. When the prepreg is laid in a curve (especially at the shoulder of the head), the inner side is subjected to pressure buckling and the outer side is subjected to stretching, which easily produces out-of-plane wrinkles (wrinkle height ≥ 0.1 mm), forming resin-rich areas and stress concentration points, weakening the overall load-bearing capacity of the cylinder, resulting in a reduction of its burst pressure by 8% to 12%.

[0008] In view of this, the present invention proposes an automatic laying and forming process for the reinforcing ring of a carbon fiber fully wound gas cylinder end cap. Summary of the Invention

[0009] This invention provides an automated process for laying and forming a carbon fiber fully wound gas cylinder end cap reinforcing ring, thus solving the above-mentioned problems.

[0010] The above-mentioned technical objective of the present invention is achieved through the following technical solution: This invention provides an automated process for laying and forming a carbon fiber fully wound gas cylinder end cap reinforcing ring, comprising the following steps: The design includes the laying pattern for the end cap section, the cylinder body section, and the cylinder laying pattern envelope; A shell-membrane hybrid unit model is adopted to achieve decoupling of prepreg tension and bending; the coupling effect of pressure roller pressure and laser heating is simulated in two stages: "pre-compaction-pre-tensioning" and "laying along the path". The strain distribution and deformation law of the prepreg are simulated and characterized by a general contact algorithm. The established multi-parameter single-objective fast optimization method takes the particle position of the particle swarm optimization algorithm as the process parameter input, substitutes it into the data-driven reduced-order surrogate model to predict the full-order displacement vector of the prepreg, calculates the wrinkle characterization to obtain the objective function value, iteratively updates the particle position until convergence, and obtains the optimal process parameters. The laying pattern is imported into the software to plan the robot's motion trajectory, and the equipment position and pressure roller contact status are adjusted. The parameters are fine-tuned to avoid interference. Carbon fiber prepreg is used, and single-layer prepreg is laid between every two spiral layers of the gas cylinder according to the optimal process parameters. The prepreg bonding status is monitored in real time.

[0011] The present invention is further configured such that: the head segment profile is derived based on the wrinkle-free forming criterion, and a differential equation for the layup angle is established under two strain critical states, which is then solved by the Runge-Kutta method to obtain the range of axial variation of the layup angle.

[0012] The present invention is further configured such that: the wrinkle-free molding criterion clarifies that when a prepreg of a specific width is laid on a curved surface without wrinkles, the quantitative relationship between the Gaussian curvature of the curved surface and the geodesic curvature of the laying trajectory is as follows: ; in, Given the Gaussian curvature of the surface, To lay out the geodesic curvature of the trajectory, The minimum forming radius for laying prepreg flat without wrinkles or defects.

[0013] The present invention is further configured such that: the profile of the cylinder section is a uniform cross-section, non-wrinkled body of revolution, and the formula for calculating the axial length corresponding to the change in its laying angle is: ; in, This represents the axial length of the cylinder corresponding to the changes in the two laying angles. Initial laying angle, To terminate the laying angle.

[0014] The present invention is further configured such that: the linear envelope of the gas cylinder is the total center rotation angle of the gas cylinder main shaft during one round-trip cycle of the pressure roller. ; in, , The center corners corresponding to the line patterns laid out for the head and body sections are respectively. For the center angle fine adjustment, The number of revolutions the core mold has made. The number of layup rings required to evenly distribute the prepreg across the cylinder section; This is the remainder after the core mold has been rotated.

[0015] The present invention is further configured such that the multi-parameter single-objective rapid optimization method takes the prepreg being wrinkle-free, strain being less than the ultimate strain, and the material utilization rate being the highest as the optimization objectives.

[0016] The present invention is further configured such that: the process parameters include laying angle, pressure roller pressure and heating temperature, and the optimal process parameters are laying angle, pressure roller pressure and heating temperature.

[0017] In summary, the present invention has the following beneficial effects: 1. Achieve fully automated and precise placement, improving production efficiency and consistency: Through an integrated system of "line design - simulation optimization - automated equipment", it replaces traditional manual / semi-automated operations, significantly improving reinforcement accuracy (carbon fiber orientation consistency error ≤1°) and batch production consistency; 2. Improve material utilization and reduce manufacturing costs: The optimized laying trajectory avoids the material waste problem of cutting the fiber in the winding reinforcement process, and the material utilization rate is increased to more than 95%. Compared with the traditional process, it reduces material consumption by 15% to 20%, which significantly reduces the overall manufacturing cost of gas cylinders. 3. Eliminate layup wrinkles and improve cylinder load-bearing safety: Based on the established wrinkle-free layup criteria and linear design method, the wrinkling problem of prepreg in the small curvature area of ​​the end cap (wrinkle height < 0.02 mm) is effectively solved, avoiding resin enrichment and stress concentration, increasing the burst pressure of the cylinder by 10%~15%, and enhancing the service safety and service life of the cylinder. 4. Quantitatively optimize process parameters to fully unleash carbon fiber performance: Through finite element simulation and particle swarm optimization algorithm, the laying parameters are quantitatively optimized to ensure that the strength of carbon fiber is fully utilized, which can meet the design requirements of high-pressure gas cylinders and expand the application scenarios of gas cylinders. Attached Figure Description

[0018] Figure 1 This refers to the range of layup angles for the left end cap prepreg without wrinkles in this embodiment of the invention. Figure 2 This is the actual laying trajectory of the end cap section in the embodiment of the present invention; Figure 3 This is a strain variation diagram of the trajectory of the end cap segment with a variable initial laying angle in an embodiment of the present invention; Figure 4 This refers to the range of laying angles for the prepreg in the cylinder section of the present invention, where there are no wrinkles or defects. Figure 5This is the laying trajectory of the cylinder section in an embodiment of the present invention; Figure 6 These are line shape effect diagrams of different numbers of prepreg layers in embodiments of the present invention; Figure 7 The reinforcement ring layout pattern in this embodiment of the invention is shown in the figure (where a is a 50mm wide reinforcement ring pattern and b is a 70mm wide reinforcement ring pattern). Figure 8 In this embodiment of the invention, Pqart software is used for robot motion trajectory planning; Figure 9 This is the movement trajectory of the gas cylinder end cap reinforcement ring laying head in this embodiment of the invention; Figure 10 This is a partial effect diagram of the 50mm wide reinforcing ring in an embodiment of the present invention; Figure 11 This is a partial effect diagram of the 70mm wide reinforcing ring in an embodiment of the present invention; Figure 12 This is an overall effect diagram of the 50mm width reinforcement molding in an embodiment of the present invention; Figure 13 This is an overall effect diagram of the 70mm width reinforcement molding in an embodiment of the present invention. Detailed Implementation

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

[0020] Example 1: An automated layup and molding process for carbon fiber fully wound gas cylinder head reinforcing rings is proposed. This process comprises three core stages: "line design - simulation optimization - equipment debugging and fabrication verification." The system establishes an automated layup and molding technology framework for carbon fiber fully wound gas cylinder head reinforcing rings. Specifically, it includes defect-free layup line design for the head and cylinder sections, prepreg layup simulation optimization, automated layup equipment debugging, and reinforcing ring fabrication. The specific steps are as follows: S100. Design and laying of lines The laying pattern includes the laying patterns for the end cap section, the cylinder body section, and the cylinder laying pattern envelope, specifically including the following steps: S110. Definition of Coordinate System and Basic Parameters Cylindrical coordinate system Describe the structure of the gas cylinder (the gas cylinder structure is a rotating body). The radial distance of the rotating body. This is the axial distance. (For the center corner of the laying), the surface of the gas cylinder is a curved surface of revolution formed by a curve rotating counterclockwise around the Z-axis; (1) Define the width of the prepreg as W, and the minimum forming radius for prepreg lay-up without wrinkles as follows: The laying angle is (The angle between the curve on the surface and the meridian of the surface), the coordinates of the curve's arc length are... .

[0021] S120. Derivation of the wrinkle-free forming criterion To avoid wrinkles and defect accumulation in prepregs during curved surface laying, this study investigates the strain variation law of prepregs of a certain width during curved surface laying and establishes a criterion for wrinkle-free prepreg curved surface laying. This criterion clarifies the Gaussian curvature of the curved surface (GG) when prepregs of a specific width do not produce wrinkles during curved surface laying. ) and the geodesic curvature of the laying trajectory ( The quantification relationship that needs to be satisfied is expressed in the following specific expression: (2) Using Liouville's formula from differential geometry, the geodesic curvature of a curve on a solid of revolution is derived. and Gaussian curvature of surfaces It can be represented as: (3) (4) in The angle between the curve on the surface and the meridian of the surface is called the layup angle. The coordinates of the arc length corresponding to the curve. The radial distance of the body of revolution with respect to the length of the curve axis The first derivative. The radial distance of the body of revolution with respect to the length of the curve axis The second derivative of .

[0022] Simultaneously, the length of the curve axis on the surface of the body of revolution Arc length laying angle Center corner and parameters The following differential equation relationship is satisfied: (5) (6) S130. Equation for the wrinkle-free line type of the end cap segment. Due to the Gaussian curvature of the surface Since the width W of the prepreg is a constant, the wrinkle-free molding criterion formula expresses the minimum molding radius for wrinkle-free prepreg laying due to the geodesic curvature of the curve and the prepreg planar layup. The relationship is as follows. Since the left-hand side of the wrinkle-free forming criterion formula has an absolute value, there are two cases. Based on the wrinkle-free forming criterion, the differential equation for the layup angle is derived for these two cases: Scenario 1: When the strain of the prepreg surface reaches the critical state, formula (2) transforms into: (7) Scenario 2: When the strain of the prepreg surface reaches the critical state, formula (2) transforms into: (8) When the prepreg is laid in the cylinder head area without wrinkles, the differential equations satisfied by the axial variation of the laying angle are as follows: (9) (10) The Runge-Kutta method is used to solve the above nonlinear differential equations to determine... The range of values ​​is used to obtain the range of variation of the laying angle along the end cap axis under the condition of fixed "gas cylinder geometric parameters - prepreg width", which provides a basis for subsequent line optimization.

[0023] S140. Defect-free line optimization of the end cap section. The defect-free linear design of the end cap section is based on a wrinkle-free laying pattern, combined with the geometry of the prepreg and the end cap, to achieve gap-free, overlap-free, and wrinkle-free laying of the prepreg. This is accomplished in three steps: Step 1: Setting the initial laying angle and calculating the number of laying turns: Taking any end cap as the research object, select the point with the smallest cross-sectional circumference at the pole hole as the laying starting point, and set the initial laying angle as... The radius of the cross-section circle at the pole hole is Based on the actual coverage width of the prepreg Calculate the number of prepreg layers required to uniformly and defect-free cover the end cap section. The formula is as follows: (11) Step 2: Initial actual forming angle Correction and calculation of laying angle for the laying trajectory: Since the number of laying loops N is rounded up, the initial laying angle needs to be corrected to ensure the coverage accuracy of the prepreg. The actual initial laying angle... The corrected formula is as follows: (12) Similarly, the laying angles at other intersections of the laying trajectory It can be calculated using the following formula: (13) The third step is to analyze the wrinkles on the laying trajectory: set a reasonable analysis range for the initial laying angle, calculate the maximum strain of the prepreg corresponding to different initial laying angle trajectories on the end cap, and compare it with the limit strain of the selected prepreg without wrinkles defects to screen out the range of initial laying angles without defects; combined with simulation analysis and verification, and taking into account the gas cylinder geometry, prepreg parameters and wrinkle criteria, the defect-free laying line of the gas cylinder end cap is finally derived.

[0024] S150. Seamless, wrinkle-free design on the tube body. The cylindrical section is a solid of revolution with a constant cross-section and a Gaussian curvature. And the radial distance relative to the axis length first derivative Second derivative Based on this, the equation for the wrinkle-free layup line of the cylinder section is derived: (14) Assuming Initial laying angle, To terminate the laying angle, The formula for calculating the axial length of the cylinder corresponding to the wrinkle-free prepreg required for the transition between two layup angles is as follows: (15) S160. Linear Envelope Analysis of Gas Cylinder Structure By designing the laying lines for the end caps and cylinder body sections as described above, a wrinkle-free, continuous transition of the prepreg on the cylinder surface can be achieved. However, in actual laying, the prepreg needs to start from the left end cap pole hole, reach the right pole hole, and then turn back. After completing one cycle, it needs to be offset by a yarn width at the cylinder equator. After several cycles, the cylinder can be fully covered. Only when the center angle reaches a specific value can the requirement of uniform coverage be met.

[0025] During the automatic placement of gas cylinders, the total center angle rotated by the main shaft of the gas cylinder during one cycle of the pressure roller's reciprocating motion is: The central corner satisfies the following relationship: (16) in, , The center corners corresponding to the laying lines for the head and body sections are respectively; The center angle is fine-tuned to ensure that the prepreg is evenly distributed across the surface of the core mold structure. This represents the total number of revolutions the core mold has made. The number of lay-up rings required to evenly distribute the prepreg across the cylinder section, but the lay-up angle involved in calculating the actual coverage width. The minimum laying angle for the cylinder section; The remainder after the core mold has been rotated is required to be an irreducible proper fraction.

[0026] S200. Prepreg Laying Simulation Optimization: A shell-membrane hybrid unit model is adopted to achieve prepreg tension-bending decoupling. The coupling effect of pressure roller pressure and laser heating is simulated in two stages: "pre-compaction-pre-tensioning" and "laying along the path". The strain distribution and deformation law of the prepreg are simulated and characterized by a general contact algorithm. A multi-parameter single-objective fast optimization method is established. The particle position of the particle swarm optimization algorithm is used as the process parameter input. It is substituted into the data-driven reduced-order surrogate model to predict the full-order displacement vector of the prepreg. The wrinkle characterization is calculated to obtain the objective function value. The particle position is iteratively updated until convergence to obtain the optimal process parameters. The specific steps are as follows: Using finite element analysis (FEA) software, the stress-strain behavior of prepreg under the coupled action of "pressure roller pressure - laser heating" during the laying process is simulated. To address the issue that commercial software lacks rotational degrees of freedom for membrane units and cannot characterize out-of-plane bending deformation, three modeling assumptions are proposed: (1) The thickness of the unidirectional prepreg is relatively thin, and the stress state during the laying process can be simplified to a plane stress state, which can be modeled and characterized by two-dimensional finite elements (shell element or membrane element). (2) The fiber stretching, in-plane shearing and out-of-plane bending deformation behaviors are independent and there is no coupling; (3) The stretching along the fiber direction and the stretching perpendicular to the fiber direction are decoupled.

[0027] Based on the above assumptions, a shell-film hybrid unit is used to achieve tension-bending decoupling of unidirectional prepreg. Membrane unit (M3D4R) and shell unit (S4R) models with the same mesh size are established respectively. By superimposing and merging common nodes, the shell-film hybrid unit model is obtained. Rigid bodies are defined at the center of the pressure roller and the center of the arc. The center fixed angular velocity is set to simulate the layup rate, and other degrees of freedom are fixed. The pressure roller applies constant pressure to ensure that the prepreg tape is in full contact and bonded to the planar substrate. The simulation process is divided into two stages: "pre-compacting-pre-tensioning" and "layup along the path". A general contact algorithm is used to model the interaction of each component and accurately simulate the strain distribution and deformation law of the prepreg.

[0028] With the optimization objectives of wrinkle-free prepreg, strain less than the ultimate strain, and maximum material utilization, a multi-parameter single-objective rapid optimization method was established. Python code was written to use the positions of all particles in a particle swarm optimization algorithm as input variables for process parameters (such as laying angle, roller pressure, and heating temperature). These input variables were substituted into an established data-driven reduced-order surrogate model to predict the full-order displacement vector of the prepreg and calculate its wrinkle characterization. The objective function values ​​of the particles were obtained and passed to the optimization algorithm. The particle positions in the optimization algorithm were recorded and updated. An iterative loop was formed based on convergence criteria to achieve global optimization of the process parameters and determine the optimal combination of process parameters.

[0029] S300. Automated Laying-out Equipment Debugging and Reinforcing Ring Preparation Equipment Selection: Pqart robot offline programming software and MOTOMAN-GP25 articulated robot are selected as the core equipment, equipped with a suitable dedicated filament placement head and pressure roller structure: The filament placement head adopts a miniaturized design to ensure flexible adaptation to small curvature areas (curvature radius ≤50mm) near the end cap aperture; the pressure roller is made of elastic material to ensure uniform pressure application during the placement process and avoid damage to the prepreg.

[0030] Track import and debugging: Import the designed laying line curve into Pqart software to automatically plan the robot's motion trajectory; debug the laying head position, mold position and pressure roller contact state through software simulation to ensure that the pressure roller is completely in contact with the mold surface and the prepreg is subjected to uniform force; use the robot teach pendant to fine-tune motion parameters (such as motion speed and turning accuracy) to avoid equipment interference during laying and ensure trajectory execution accuracy.

[0031] Reinforcing ring preparation: Using carbon fiber prepreg, according to the optimized process parameters (layout angle, pressure roller pressure, heating temperature), a single layer of prepreg is laid between every two spiral layers of the gas cylinder, and the layers are stacked one by one to form the head reinforcing ring; the prepreg bonding status is monitored in real time during the laying process to ensure that there are no wrinkles or bubbles, and finally the reinforcing ring preparation is completed.

[0032] Example 2: To verify the versatility and reliability of the linear design of this invention, a gas cylinder structure with unequal polarity holes was selected as the research object. Through specific parameter calculations and simulation verification, the design effect of the defect-free laying linear shape was clarified, as follows: The structural dimensions of the unequal-electrode gas cylinder are as follows: major semi-axis R = 53mm, minor semi-axis b = 50mm, left and right end cap heights h1 = 46mm and h2 = 42mm respectively, and cylinder length L = 200mm. The prepreg width W = 6.35mm, and the minimum forming radius for prepreg lay-up without wrinkles is specified. =300mm. Assuming the initial laying angle of the left end cap is 60°, according to equations (8) and (9), the range of the final laying angle variation for the prepreg section near the cylinder body without wrinkles is [8.03°, 18.04°]∪[21.54°, 31.55°]. The laying angle varies along the axial direction of the end cap as follows: Figure 1 As shown Combining the formula for calculating the center angle, the Runge-Kutta method is used to obtain the center angle of the laying path at the corresponding laying angle. Draw the 3D laying path of the end cap as follows Figure 2 .Depend on Figure 1 It can be seen that, with the prepreg laid flat, the minimum forming radius without wrinkles is... Approaching infinity (selected in this article) for (Infinite value), the laying trajectory of the end cap segment will approach the geodesic curve with an initial angle of 60°, but will not coincide with the geodesic curve. The core reason is that the prepreg with a certain width is affected by the Gaussian curvature of the end cap surface and the geodesic curvature of the laying path. Even if laid along the geodesic line, the equivalent forming radius of the prepreg may still be greater than 100°. This leads to wrinkle defects, thus verifying the necessity of the wrinkle-free criterion of the present invention.

[0033] Three initial laying angles (0°, 45°, 90°) were set. The corrected actual initial laying angle and laying envelope number were calculated by formulas (17) and (18), and the corresponding laying trajectory was drawn as shown in Table 1. It can be seen that the prepreg is laid without gaps, overlaps, or wrinkles under the three initial laying angles.

[0034] The obtained layup trajectory is analyzed using wrinkle criteria to determine wrinkle defects. Taking the right end cap of a gas cylinder as an example, the minimum forming radius for wrinkle-free prepreg layup is adjusted. =30mm. Assuming the initial layup angle analysis range is [0°, 90°], the maximum strain of the prepreg corresponding to different initial layup angle trajectories of the right end cap is calculated using formulas (1) and (2), and compared with the ultimate strain of the selected prepreg without wrinkles or defects, such as... Figure 3 As shown, since the initial laying angle needs to be corrected based on the number of laying tracks after being given, a certain range of initial laying angles correspond to the same actual initial laying angles and the same laying tracks. Therefore... Figure 3 A stepped, broken-line strain value will appear. Based on the calculation results, the initial angle selection range for the defect-free right end cap is determined to be [60.56°, 90°].

[0035] Through simulation analysis and verification, the geometric dimensions of the cylinder body and prepreg are comprehensively analyzed. Combined with the prepreg wrinkle criterion, the defect-free line shape of the cylinder structure end cap is derived. This line shape can effectively cover the end cap without gaps, overlaps, or wrinkles.

[0036] Taking the gas cylinder body mentioned above as an example, assuming the initial laying angle is 20°, the minimum forming radius for adjusting the prepreg plane to avoid wrinkles is determined. =1800mm, according to formula (17), the range of the prepreg laying angle without wrinkles in the cylinder section is [13.35°, 26.94°], and the laying angle varies along the cylinder axis as follows. Figure 4 The layup angle range of the prepreg section without wrinkles is shown in the figure. The actual layup trajectory of the prepreg section is as follows. Figure 5 As shown.

[0037] Prepreg When the value approaches infinity, the wrinkle-free laying trajectory of the cylinder section coincides with the geodesic curve, indicating that prepreg with a certain width is not prone to wrinkle defects when laid on the geodesic trajectory of a rotating body with a constant cross section.

[0038] Gas cylinder structural linear envelope analysis Linear envelope analysis is performed on the gas cylinder structure and prepreg given above, and the minimum forming radius for wrinkle-free prepreg planar layup is set. =300mm, with the starting laying angles of the left and right end caps being 60° and 30° respectively. Calculations show the ending laying angle ranges for the left and right end caps to be [8.03°, 18.04°]∪[21.54°, 31.55°] and [5.71°, 14.19°]∪[17.27°, 26.03°]. Setting the ending laying angles of the left and right end caps to 25° and 10° respectively, the constant laying angle range for the cylinder section is obtained as [0°, 39.15°]. Then, 30° is selected as the constant laying angle for the cylinder section. The calculated Y value is 52. , The values ​​are 164.62° and 201.84°. With M value set to 2 and k value set to 37, the center rotation angle fine-tuning amount is calculated. The angle is 97.39°. Based on the above data, the prepreg molding effect under different numbers of cylinder stacking rings is plotted as follows: Figure 6 As shown. The minimum laying angle for the cylinder section is 10°, and the minimum coverage of the prepreg in the cylinder section is: (17) Since the number of prepreg layers in the cylinder section is usually obtained by rounding up, the coverage value is typically greater than 100%. This is acceptable in the actual laying of gas cylinder structures.

[0039] Head reinforcement ring shape design and fabrication verification Based on the principle of wrinkle-free laying of the end cap, the design incorporates two reinforcing rings in the end cap area of ​​the Φ480mm gas cylinder, with widths of 50mm and 70mm respectively. The lines are as follows: Figure 7 As shown.

[0040] After obtaining the wrinkle-free layup line of the prepreg head, the curves on the line are imported into the Pqart robot offline programming software, such as... Figure 8 As shown, the positions of the laying head, the end cap reinforcement ring laying and forming mold, and other mechanisms are adjusted. The laying motion trajectory of the end cap reinforcement robot is planned to ensure that the pressure roller structure is in complete contact with the mold surface, the prepreg is subjected to uniform force, and the molding is wrinkle-free.

[0041] get Figure 9 After tracking the yellow robot's movement trajectory, the debugged code was imported into the robot's indicator to begin laying and fabricating the reinforcing rings. Ultimately, reinforcing ring structures with widths of 50mm and 70mm were obtained. (Observation follows.) Figure 10 and Figure 11 The partial effect diagrams of the two reinforcing rings show that the prepreg is tightly arranged within the effective area of ​​the reinforcing rings, without any wrinkles or defects. Figure 12 and Figure 13 This is an image showing the overall molding effect of the two reinforcing rings. The surface fibers are tightly arranged and there are no wrinkles or defects.

[0042] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automated process for laying and forming a carbon fiber fully wound gas cylinder end cap reinforcing ring, characterized in that: Includes the following steps: The design includes the laying pattern for the end cap section, the cylinder body section, and the cylinder laying pattern envelope; A shell-membrane hybrid unit model is adopted to achieve decoupling of prepreg tension and bending; the coupling effect of pressure roller pressure and laser heating is simulated in two stages: "pre-compaction-pre-tensioning" and "laying along the path". The strain distribution and deformation law of the prepreg are simulated and characterized by a general contact algorithm. The established multi-parameter single-objective fast optimization method takes the particle position of the particle swarm optimization algorithm as the process parameter input, substitutes it into the data-driven reduced-order surrogate model to predict the full-order displacement vector of the prepreg, calculates the wrinkle characterization to obtain the objective function value, iteratively updates the particle position until convergence, and obtains the optimal process parameters. Import the laying pattern into the software to plan the robot's motion trajectory, adjust the equipment position and the contact state of the pressure roller, and fine-tune the parameters to avoid interference; Carbon fiber prepreg is used, and single-layer prepreg is laid between every two spiral layers of the gas cylinder according to the optimal process parameters, and the bonding status of the prepreg is monitored in real time.

2. The automatic layup and molding process according to claim 1, characterized in that: The head segment profile is derived based on the wrinkle-free forming criterion. The layup angle differential equation is established under two strain critical states and solved by the Runge-Kutta method to obtain the range of layup angle variation along the axial direction.

3. The automatic layup and molding process according to claim 2, characterized in that: The wrinkle-free molding criterion clarifies the quantitative relationship between the Gaussian curvature of the surface and the geodesic curvature of the laying trajectory when a prepreg of a specific width lays on a curved surface without wrinkles, as follows: ； in, Given the Gaussian curvature of the surface, To lay out the geodesic curvature of the trajectory, The minimum forming radius for laying prepreg flat without wrinkles or defects.

4. The automated layup and molding process according to any one of claims 1-3, characterized in that: The cylindrical section profile is a uniform cross-section, wrinkle-free rotating body profile. The formula for calculating the axial length corresponding to the change in its laying angle is as follows: ； in, This represents the axial length of the cylinder corresponding to the changes in the two laying angles. Initial laying angle, To terminate the laying angle.

5. The automatic layup and molding process according to claim 1, characterized in that: The cylinder's linear envelope is the total center rotation angle of the cylinder's main shaft during one round-trip cycle of the pressure roller. ； in, , The center corners corresponding to the line patterns laid out for the head and body sections are respectively. For the center angle fine adjustment, The number of revolutions the core mold has made. The number of layup rings required to evenly distribute the prepreg across the cylinder section; This is the remainder after the core mold has been rotated.

6. The automatic layup and molding process according to claim 1, characterized in that: The multi-parameter single-objective rapid optimization method takes the prepreg being wrinkle-free, strain being less than the ultimate strain, and the material utilization rate being the highest as the optimization objectives.

7. The automatic layup and molding process according to claim 1, characterized in that: The process parameters include laying angle, pressure roller pressure, and heating temperature, and the optimal process parameters are laying angle, pressure roller pressure, and heating temperature.

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