Narrow-band CF / PEEK automatic fiber placement crystallinity regulation and control method

Abstract

The invention relates to a narrow-band CF / PEEK automatic fiber placement crystallinity regulation and control method. The method comprises the following steps: S1, performing tension stabilization control on the prepreg, so that the prepreg is in a stable feeding state within a preset tension range before entering a paving process; s2, paving operation is executed according to the target crystallinity, paving parameters are matched and set according to a temperature T-speed V-pressure P coordinated regulation and control model in the paving process, and the material forms a crystallization trend corresponding to the target crystallinity in the paving stage; s3, performing programmed speed-controlled cooling linked with the target crystallinity on the paved workpiece so as to lock a crystal structure formed in the paving stage; the cooling rate is in negative correlation with the target crystallinity. According to the method, the crystallinity of the narrow-band CF / PEEK component can be stably controlled in a preset narrow range, and the distribution uniformity of the crystallinity in a component surface is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of automated molding technology for composite materials, and in particular to a method for controlling the crystallinity of narrow-band CF / PEEK automatic fiber placement. Background Technology

[0002] Carbon fiber reinforced polyetheretherketone (CF / PEEK) composites have become key materials for lightweighting and high-performance applications in high-end equipment such as aerospace due to their superior specific strength, high-temperature resistance, and fatigue resistance. Automated fiber placement (AFP) technology, as a core automated means of manufacturing large and complex composite components, has made it possible to achieve efficient and precise molding of CF / PEEK structures.

[0003] As component designs become increasingly sophisticated and complex, the advantages of using narrow prepreg bundles for layup are becoming increasingly apparent: it can better conform to complex curved surfaces, reduce wrinkles and bridging, and improve surface quality and dimensional accuracy. However, the significant reduction in prepreg width brings about a strong "size effect," causing existing general-purpose AFP processes developed based on wide prepreg tapes to reveal a series of inherent defects with different and difficult-to-reconcile mechanisms when directly applied to narrow-band CF / PEEK: 1. The Challenges of Thermal Response Mismatch and Crystallization Uniformity: Narrow-band fiber bundles have an extremely large specific surface area, resulting in a very rapid thermal response during layup and heating, with a short and intense thermal history. Existing processes typically use fixed or relatively wide ranges of temperature and speed parameters, which cannot adapt to this rapid and unsteady thermal process. As a result, the melting and crystallization of PEEK resin are severely uneven in time and space, easily forming a "mosaic" structure with alternating high and low crystallinity zones inside the component. This becomes a weak point in mechanical properties and a potential source of failure. The uncontrollable and uneven crystallinity is the primary bottleneck restricting the performance consistency of narrow-band components.

[0004] 2. The "Immersion-Morphology" Control Conflict: Sufficient heat and pressure are required to ensure adequate fusion and interfacial bonding between narrow bands. However, molten PEEK resin is easily extruded laterally from narrow filament bundles under high pressure, causing a localized surge in fiber volume fraction, deformation of the filament bundle cross-section (such as collapse), and the formation of pores or resin-poor bands at the edges of adjacent filament bundles. Existing process parameters (such as temperature and pressure) are mostly independently controlled, lacking a synergistic constraint mechanism for the characteristics of narrow bands, making it difficult to achieve a balance between "ensuring adequate immersion" and "maintaining the integrity of the filament bundle morphology."

[0005] 3. Dispersion and Instability of Interlayer Properties: Due to the aforementioned issues, the distribution, crystallization state, and interfacial bonding quality of the interlayer resin in narrow-band laid components exhibit high randomness. This directly manifests as large dispersion coefficients and poor batch repeatability in interlayer shear strength (ILSS) and impact resistance data. Existing technologies often attempt to remedy this through subsequent autoclave processes, but these are costly and cannot fundamentally address the inherent defects formed during the laying process.

[0006] 4. Lack of a comprehensive, systematic control strategy: Current research and practice often focus on the isolated optimization of local parameters (such as temperature and pressure) of the bonding head, neglecting the systemic impact of the entire process, from the inherent stress control during prepreg cutting and tray loading, to the multi-physics coupling during the bonding process, and finally to the management of the cooling process after molding. In particular, it fails to recognize the potential influence of the tension state of the preceding process on the thermal behavior and crystallization kinetics of the resin in subsequent bonding, as well as the crucial role of the cooling rate as the "final crystallization lock," leading to a break in the process control chain and making it impossible to achieve precise "end-to-end" programming of the core structural parameter of crystallinity.

[0007] Therefore, the industry urgently needs an innovative process designed specifically for narrowband CF / PEEK that can systematically solve the thermo-mechanical process mismatch caused by the narrowband size effect, thereby achieving precise, stable, and predictable control from microcrystalline structure to macroscopic mechanical properties. Summary of the Invention

[0008] This invention covers the following technical solutions: One aspect of the present invention relates to an automatic CF / PEEK fiber placement method for controlling crystallinity, comprising the following steps: S1, tension stabilization control is implemented on the prepreg to ensure that it is in a stable supply state within a preset tension range before entering the laying process; S2, Perform the laying operation according to the target crystallinity. During the laying process, the laying parameters are matched and set according to the temperature T-speed V-pressure P coordinated control model, so that the material forms a crystallization trend corresponding to the target crystallinity during the laying stage, wherein: When the target crystallinity is ≥35%, the laying speed V is adjusted to the low speed end and V≤0.08 m / s, the laying temperature T is adjusted to the high temperature end and T≥410 ℃, and the laying pressure P is adjusted to the high pressure end and P≥250 N. When the target crystallinity is 25% to 30%, the laying speed V should be 0.08 m / s < V < 0.12 m / s, the laying temperature T should be 390 ℃ < T < 410 ℃, and the laying pressure P should be 150 N < P < 250 N. When the target crystallinity is ≥20% and <25%, the laying speed V is adjusted towards the high-speed end and V≥0.12 m / s is adopted; the laying temperature T is adjusted towards the near melting limit temperature or lower end and T≤390 ℃ is adopted; and the laying pressure P is adjusted towards the low-pressure end and P≤150 N is adopted. S3, implement programmed speed-controlled cooling of the completed part in conjunction with the target crystallinity to lock the crystalline structure formed during the laying stage; the cooling rate is negatively correlated with the target crystallinity.

[0009] Another aspect of the present invention relates to a narrow-band CF / PEEK automatic fiber placement crystallinity control system, the system comprising: Target crystallinity setting module, parameter co-calculation module, layup control module, and cooling control module; The target crystallinity setting module is used to receive and store the target crystallinity parameters of the part to be formed; The parameter collaborative calculation module is used to generate a combination of paving process parameters corresponding to the target crystallinity based on the temperature T-speed V-pressure P collaborative control model. The laying control module is used to receive the laying process parameter combination output by the parameter co-calculation module, and control the automatic fiber placement equipment to perform the laying operation according to the laying temperature, laying speed and laying pressure, so that the material forms a preset crystallization trend during the laying stage; The cooling control module is used to receive the target crystallinity parameter and control the programmed speed cooling process of the part according to the target crystallinity parameter, so that the cooling rate matches the target crystallinity, thereby locking the crystalline structure formed in the laying stage. When the system is running, the method described above is executed.

[0010] Another aspect of the present invention relates to a computer-readable storage medium for storing computer instructions, programs, code sets or instruction sets, which, when run on a computer, cause the computer to perform the functions corresponding to the crystallinity setting module, parameter co-calculation module, tiling control module and cooling control module described in the system above.

[0011] Another aspect of the present invention relates to an electronic device comprising: One or more processors; and A computer-readable storage medium for storing computer instructions, programs, code sets, or instruction sets, which, when executed on a computer, enable the one or more processors to perform the functions corresponding to the crystallinity setting module, parameter co-calculation module, tiling control module, and cooling control module described in the system above.

[0012] This invention constructs a temperature-speed-pressure coordinated control model dominated by the laying speed, and organically links the stable control of raw material tension, the coordinated matching of laying parameters, and the programmed speed-controlled cooling process. This enables programmable control of crystallinity during the automatic filament placement process of narrow-band CF / PEEK. By implementing this solution, the crystallinity of narrow-band CF / PEEK components can be stably controlled within a preset narrow range, and the uniformity of crystallinity distribution within the component surface can be significantly improved. The corresponding mechanical properties (such as interlaminar shear strength, flexural strength, and impact toughness) can be precisely matched and highly repeatable according to design requirements, systematically solving the various problems of narrow-band laying described in the background art. Attached Figure Description

[0013] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 : The high crystallinity DSC curve corresponding to Example 1.

[0015] Figure 2 : The DSC curve corresponding to the medium crystallinity in Example 2.

[0016] Figure 3 : The low crystallinity DSC curve corresponding to Example 3. Detailed Implementation

[0017] Reference will now be made to detailed embodiments of the present invention, one or more of which are described below. Each example is provided for explanation and not for limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0018] Unless otherwise stated, all terms used to disclose this invention (including technical and scientific terms) should be understood as having the meaning commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of protection of this invention. Unless the context clearly defines otherwise, the scientific and technical terms used herein, as well as terms and laboratory procedures in related disciplines such as composite materials engineering, thermoplastic polymer science, materials physics and crystallization kinetics, automated manufacturing and CNC control technology, multiphysics coupled heat and mass transfer theory, and advanced composite material molding processes, are all conventional terms and standard methods well-known and widely used in the art. To facilitate understanding of the technical solutions of this invention, some related terms are further defined and explained below.

[0019] The terms “containing,” “comprising,” and “including” as used in this invention are synonyms and are inclusive or open-ended, not excluding additional, uncited members, elements, or method steps.

[0020] In this invention, the numerical range represented by endpoints includes all numerical values ​​and fractions contained within that range, as well as the endpoints mentioned.

[0021] Furthermore, in describing representative embodiments of the invention, this specification may present the methods and / or processes of the invention as a specific sequence of steps. However, the method or process should not be limited to the specific order of the steps described herein, to the extent that the method or process does not depend on the specific order of the steps presented herein. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps presented in the specification should not be construed as a limitation of the claims. Additionally, the claims relating to the methods and / or processes of the invention should not be limited to the execution of their steps in the order they are written, and those skilled in the art will readily recognize that the sequence can be changed while still remaining within the spirit and scope of the invention.

[0022] As used in this invention, unless otherwise stated, the singular forms of the articles “a,” “an,” and “the” include plural referents.

[0023] In this invention, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity of 2 or more.

[0024] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0025] In this invention, terms such as "preferred," "better," "more suitable," and "ideal" merely describe implementation methods or embodiments with better effects and should be understood not to limit the scope of protection of this invention. In this invention, terms such as "optionally," "optionally," and "optional" mean that something is optional, that is, selected from either "with" or "without" a parallel solution. If multiple "optional" statements appear in a technical solution, unless otherwise specified and without contradiction or mutual constraint, each "optional" statement is independent.

[0026] In this invention, the term "narrow band" refers to carbon fiber reinforced polyetheretherketone prepreg bundles used for automated filament laying. The width of a single bundle is significantly smaller than that of conventional prepreg tapes. It has the characteristics of large specific surface area, fast thermal response speed and narrow process window, and is generally highly sensitive to changes in temperature, speed and pressure parameters during the laying process.

[0027] In this invention, the term "target crystallinity" refers to the desired degree of crystallinity of PEEK resin in the CF / PEEK composite material, which is pre-set according to the performance requirements of the part. It is expressed as a mass percentage and serves as an input benchmark for setting laying parameters and controlling cooling parameters.

[0028] In this invention, the term "crystallization tendency" refers to the comprehensive characterization of the orientation state of resin molecular chains, nucleation density, and crystal growth potential formed by a specific combination of temperature, speed, and pressure during the laying stage. It is used to reflect the structural basis of the material's tendency to evolve towards a specific level of crystallinity during subsequent cooling.

[0029] In this invention, the term "programmed speed-controlled cooling" refers to the controlled cooling treatment of the part after the tiling is completed by a pre-set and automatically executed cooling program, so that the cooling rate changes in accordance with the law matching the target crystallinity, thereby guiding and locking the crystallization trend formed during the tiling stage and avoiding the randomization of structure caused by natural cooling.

[0030] In this invention, the term "tension stabilization control" refers to setting, monitoring, and adjusting the tension acting on the prepreg during processes such as prepreg cutting, traying, and wire feeding before it enters the laying process. This ensures that the prepreg maintains a stable and consistent stress state before entering the laying process, thereby suppressing the adverse effects of residual stress, micro-buckling, and wire feeding fluctuations on the molding quality.

[0031] In this invention, the term "negative correlation cooling relationship" refers to the inverse relationship between the cooling rate and the target crystallinity during programmed rate-controlled cooling. That is, the higher the target crystallinity, the lower the cooling rate used; the lower the target crystallinity, the higher the cooling rate used, so as to meet the kinetic conditions required for the formation of different crystal structures.

[0032] In this invention, the term "laying speed dominant parameter" refers to a control method in which laying speed is used as the core control variable that determines the heat treatment time and heat history length per unit length in the collaborative control model, and laying temperature and laying pressure are dynamically matched and adjusted based on this.

[0033] This invention relates to a method for automatically controlling the crystallinity of narrow-band CF / PEEK fiber placement, which includes the following steps: S1, tension stabilization control is implemented on the prepreg to ensure that it is in a stable supply state within a preset tension range before entering the laying process; S2, Perform the laying operation according to the target crystallinity. During the laying process, the laying parameters are matched and set according to the temperature T-speed V-pressure P coordinated control model, so that the material forms a crystallization trend corresponding to the target crystallinity during the laying stage, wherein: When the target crystallinity is ≥35%, the laying speed V is adjusted to the low speed end and V≤0.08 m / s, the laying temperature T is adjusted to the high temperature end and T≥410 ℃, and the laying pressure P is adjusted to the high pressure end and P≥250 N. When the target crystallinity is 25% to 30%, the laying speed V should be 0.08 m / s < V < 0.12 m / s, the laying temperature T should be 390 ℃ < T < 410 ℃, and the laying pressure P should be 150 N < P < 250 N. When the target crystallinity is ≥20% and <25%, the laying speed V is adjusted towards the high-speed end and V≥0.12 m / s is adopted; the laying temperature T is adjusted towards the near melting limit temperature or lower end and T≤390 ℃ is adopted; and the laying pressure P is adjusted towards the low-pressure end and P≤150 N is adopted. S3, implement programmed speed-controlled cooling of the completed part in conjunction with the target crystallinity to lock the crystalline structure formed during the laying stage; the cooling rate is negatively correlated with the target crystallinity.

[0034] The laying stage (S2) is the "design and initial formation stage of the crystal structure": through the "temperature (T)-speed (V)-pressure (P) coordinated control model," a specific thermo-mechanical environment is set for the PEEK resin at the moment of laying. This environment directly determines the resin's melting state, the degree of relaxation of molecular chains, and the initial driving force and nucleation tendency of crystallization. For example, the "low speed-high temperature-high pressure" combination not only promotes wetting but also creates a large number of crystal nuclei at the interface and in the confined space, presupposing a strong tendency for high crystallinity; the "high speed-near melting temperature-low pressure" combination aims to suppress crystal nucleus formation to the maximum extent, "freezing" the amorphous tendency at the moment of laying.

[0035] One of the core innovations of this invention lies in revealing that the three parameters—temperature (T), velocity (V), and pressure (P)—do not act independently on narrowband CF / PEEK layup, but rather exhibit a strongly coupled synergistic relationship. Any parameter setting that deviates from this synergistic relationship, even if it partially solves a single problem, will inevitably trigger new and more severe failure modes, making it impossible to simultaneously optimize crystallinity and overall performance. To verify this point, we conducted comparative experiments and found that: 1. If only the speed (V) is increased to shorten the thermal history (intending to reduce crystallinity), but the pressure (P) is not reduced in tandem: During high-speed layup, the contact time between the filament bundle and the die is short, requiring sufficient pressure to ensure instantaneous bonding. If the pressure is too high, the molten resin will be extruded at high speed in a very short time, resulting in exposed fibers and a surge in porosity; if the pressure is too low, the interlaminar bonding will be weak, resulting in initial defects. Both lead to a significant decrease in interlaminar shear strength (ILSS) and extremely high dispersion.

[0036] 2. If only the temperature (T) is increased to promote crystallization (intending to increase crystallinity), but the rate (V) is not reduced and the pressure (P) is not adjusted: High temperature provides the driving force for crystallization, but if the spread is too fast, the effective thermal action time is insufficient, and the crystallization process is interrupted, resulting in an imperfect crystal structure. At the same time, the resin viscosity decreases sharply at high temperature. If a "sealing effect" is not used to generate high pressure, the resin will be severely lost, creating resin-deficient areas, leading to increased porosity and severely impairing mechanical properties.

[0037] 3. If only pressure (P) is increased to improve wetting, but temperature (T) and speed (V) are not optimized in conjunction: if the temperature is insufficient or the speed is too fast, high pressure cannot promote the resin to flow and wet fully. Instead, it will "mechanically" extrude the resin that has not been fully melted, destroy the fiber bundle shape, and may damage the fibers. During the laying process, fiber bundle twisting and displacement may occur.

[0038] The failure modes described above indicate that traditional "single-variable optimization" or "fixed parameter combination" strategies fail when dealing with the "size effect" of narrowband CF / PEEK.

[0039] This invention creates a continuous and stable thermo-mechanical coupling environment throughout the molding process, which enables the crystallinity of the CF / PEEK composite material to be stably controlled within a preset range. This effectively reduces the spatial dispersion and batch fluctuation of the crystal structure, and reduces the generation of defects such as porosity, resin deficiency, and poor interlayer bonding. As a result, it significantly improves the interlayer shear strength, bending performance, and service reliability of the parts, and enhances the repeatability and engineering applicability of the narrow-strip automatic fiber placement molding process.

[0040] In some embodiments, in step S1, the slitting tension is 8 to 12 N (e.g., 9, 10, 11 N), the tray loading tension is 10 to 30 N (e.g., 15, 20, 25 N), and the absolute value of the difference between the tray loading tension and the slitting tension is not greater than 5 N.

[0041] In some implementations, in step S1, the tension fluctuation of the prepreg is monitored and adjusted in real time to keep the tension fluctuation amplitude within ±2 N.

[0042] By setting the above tension range and matching relationship, the present invention can significantly improve the stability and repeatability of the raw material supply process, reduce the interference of raw material state fluctuations on the crystallization process, and ensure the predictability and consistency of the crystallization trend control effect in the laying stage from the source.

[0043] In some embodiments, in step S3, when the target crystallinity is ≥35%, the cooling rate is 3-5 °C / min; when the target crystallinity is 25-30%, the cooling rate is 7-8 °C / min; and when the target crystallinity is ≥20% and <25%, the cooling rate is 10-12 °C / min.

[0044] Step S3 is the "final solidification and stabilization stage of the crystalline structure." After installation, the component is still at a high temperature, and the molecular chains have high mobility. If the cooling process goes out of control at this time (such as natural cooling), the crystallization trend preset in the installation stage will not be stably achieved.

[0045] The core function of programmed rate-controlled cooling is to guide and "lock in" the pre-set crystallization process during the laying stage with a controlled cooling rate that matches the target crystallinity. Slow cooling provides sufficient time for crystal nucleus growth, achieving the preset target of high crystallinity; rapid cooling quickly crosses the crystallization temperature window, solidifying the preset amorphous trend into a stable structure. Through the cooling rate settings corresponding to the above-mentioned zones, this invention makes the cooling stage a crucial control link that works synergistically with the laying stage, effectively avoiding problems such as crystallization structure regression, disorder, or uneven distribution caused by uncontrolled cooling, thereby further improving the accuracy, stability, and batch consistency of part crystallinity control.

[0046] In some embodiments, in step S3, before the programmed controlled-rate cooling, the laid-up part is subjected to a heat-monopolizing treatment at 120–180 °C (e.g., 130, 140, 150, 160, 170 °C) for 10–40 min (e.g., 20, 25, or 30 min). This heat-monopolizing process effectively promotes the redistribution of heat between layers, keeping the resin system in a relatively stable thermal equilibrium state and preventing asynchronous crystallization or local structural distortion caused by excessive temperature differences between the inner and outer layers when directly entering the cooling stage. Simultaneously, appropriate heat preservation treatment also helps release some of the thermal and internal stresses accumulated during the laying stage, improving the relaxation and rearrangement conditions of the resin molecular chains, and providing a more stable thermal environment for the orderly growth of the crystal structure during the subsequent controlled cooling process.

[0047] In some implementations, the coordinated control model uses the laying speed V as the dominant parameter determining the heat treatment time, and dynamically matches and adjusts the laying temperature T and laying pressure P according to the laying speed V.

[0048] By treating T, V, and P as a holistic system, and using velocity (V) as the key variable determining the length of the thermal history, dynamically matching the corresponding temperature (T) and pressure (P) allows for a better simultaneous achievement of the three major objectives of "controllable crystallinity," "sufficient wetting," and "intact morphology" within a narrow process window. This invention is based on this profound understanding and constructs the aforementioned whole-process coordinated control method.

[0049] In some embodiments of the present invention, the laying temperature, laying speed, and laying pressure are monitored in real time during the laying process. This can be achieved, for example, by continuously collecting data from temperature sensors, speed encoders, and pressure sensors arranged on the heating device, pressure roller assembly, and motion actuators, and transmitting the collected signals to the control system for analysis and processing. The control system compares and judges the real-time acquired temperature, speed, and pressure data based on preset target crystallinity parameters and a collaborative control model. When the monitoring results deviate from the set range, it automatically outputs adjustment commands to dynamically correct the corresponding execution units, thereby ensuring that the laying process remains stable and controllable.

[0050] The aforementioned real-time monitoring and feedback adjustment mechanism effectively suppresses parameter drift caused by factors such as equipment response lag, environmental fluctuations, or changes in material state, ensuring consistency in heat treatment time, pressure state, and melting behavior during the laying process. Simultaneously, this feedback adjustment method enables fine-tuning control without affecting the continuity of laying, avoiding process fluctuations caused by manual intervention or offline adjustments, thereby further improving the repeatability and predictability of the crystallization trend formation process.

[0051] In a further embodiment of the present invention, when the paving path includes small-radius curves, sharp turns, or obvious curved structures, the control system identifies the current paving state based on path planning information or real-time motion trajectory data and automatically triggers the corresponding parameter adjustment strategy. Since the paving contact state and heat conduction conditions are prone to change in curved areas, using straight-line parameters can easily lead to insufficient local melting, poor adhesion, or abnormal crystallization structures. Therefore, targeted optimization of the process parameters is necessary.

[0052] Specifically, when entering small-radius curves or bending regions, the system preferentially reduces the laying speed V to extend the thermal interaction time per unit length of material, allowing the resin to achieve more complete melting and molecular chain rearrangement conditions. Simultaneously, the laying temperature T and laying pressure P are adjusted according to the speed changes to compensate for variations in heat input and contact pressure fluctuations caused by changes in motion, thereby maintaining a stable thermo-mechanical coupling environment. Through this synergistic adjustment method, problems such as insufficient local crystallization, over-crystallization, or decreased interlayer bonding performance in bending regions can be effectively avoided.

[0053] In some embodiments, the programmed rate-controlled cooling employs either linear or stepped cooling. Specifically, linear cooling reduces the part temperature at a constant rate within a preset time, allowing the resin system to complete the evolution of its crystal structure in a continuous and gentle thermal environment, which is beneficial for forming a uniform crystal morphology. Stepped cooling, on the other hand, maintains or slowly lowers the temperature in stages within multiple temperature ranges, allowing the resin molecular chains sufficient rearrangement and growth time within the critical crystallization temperature range, thereby further enhancing the controllability and stability of the crystal structure. Through the rational selection and combination of the above-mentioned different cooling modes, this invention can flexibly adjust the cooling process according to different target crystallinity requirements, effectively connecting the cooling stage with the laying stage and avoiding interference from sudden temperature changes on the crystallization trend.

[0054] Furthermore, the programmed speed-controlled cooling is carried out in a closed or semi-closed heating environment. This reduces the impact of external airflow, ambient temperature differences, and other factors on the cooling process.

[0055] In some embodiments, the width of the narrow-band CF / PEEK prepreg is 3–10 mm, for example, 4, 5, 6, 7, 8, or 9 mm. The smaller width allows the prepreg to have a faster thermal response and higher temperature uniformity during heating, which is beneficial for the temperature-velocity-pressure synergistic control model to finely control the local thermal history, thereby improving the sensitivity and consistency of crystallization trend regulation.

[0056] In some embodiments, the resin content of the prepreg is 30% to 40%. An appropriate resin content can better match the resin melting behavior, crystallization kinetics, and compressive flow characteristics with the synergistic control model of the present invention, avoiding problems such as insufficient wetting and reduced strength due to too low resin content, or flow runaway, lateral extrusion, and reduced fiber volume fraction due to too high resin content, thereby further ensuring the stability of the crystallinity control effect and the consistency of the mechanical properties of the parts.

[0057] This invention also relates to a narrow-band CF / PEEK automatic fiber placement crystallinity control system, the system comprising: Target crystallinity setting module, parameter co-calculation module, layup control module, and cooling control module; The target crystallinity setting module is used to receive and store the target crystallinity parameters of the part to be formed; The parameter collaborative calculation module is used to generate a combination of paving process parameters corresponding to the target crystallinity based on the temperature T-speed V-pressure P collaborative control model. The laying control module is used to receive the laying process parameter combination output by the parameter co-calculation module, and control the automatic fiber placement equipment to perform the laying operation according to the laying temperature, laying speed and laying pressure, so that the material forms a preset crystallization trend during the laying stage; The cooling control module is used to receive the target crystallinity parameter and control the programmed speed cooling process of the part according to the target crystallinity parameter, so that the cooling rate matches the target crystallinity, thereby locking the crystalline structure formed in the laying stage. When the system is running, the method described above is executed.

[0058] The crystallinity control system of this invention can be widely applied in the manufacturing process of composite materials in fields such as aerospace structural components, rail transit load-bearing components, high-end equipment shells, UAV airframe components, and key load-bearing components for new energy vehicles. It is particularly suitable for engineering applications with high requirements for batch consistency, long-term service reliability, and performance predictability. By introducing the system of this invention, the standardized design and stable manufacturing of the crystal structure of narrow-band CF / PEEK components can be achieved, providing reliable technical support for the large-scale and intelligent production of high-performance thermoplastic composite materials.

[0059] The present invention also relates to a computer-readable storage medium for storing computer instructions, programs, code sets or instruction sets, which, when run on a computer, cause the computer to perform the functions corresponding to the crystallinity setting module, parameter co-calculation module, tiling control module and cooling control module described in the system above.

[0060] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory, optical storage devices, magnetic storage devices, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0061] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including—but not limited to—electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of transmitting, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0062] The program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0063] Computer program code for performing the operations of this disclosure can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0064] The present invention also relates to an electronic device comprising: One or more processors; and A computer-readable storage medium for storing computer instructions, programs, code sets, or instruction sets, which, when executed on a computer, enable the one or more processors to perform the functions corresponding to the crystallinity setting module, parameter co-calculation module, tiling control module, and cooling control module described in the system above.

[0065] In some embodiments, the electronic device may also include a transceiver. The processor and the transceiver are connected, such as via a bus. It should be noted that in practical applications, the transceiver is not limited to one unit, and the structure of the electronic device does not constitute a limitation on the embodiments of this application.

[0066] The processor can be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor can also be a combination that implements computational functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0067] A bus can include a pathway for transmitting information between the aforementioned components. The bus can be a PCI bus or an EISA bus, etc. Buses can be categorized as address buses, data buses, control buses, etc.

[0068] The embodiments of the present invention will be described in detail below with reference to the examples. It should be understood that these embodiments are only used to illustrate the technical content of the present invention and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the specific experimental conditions in the following embodiments are given priority reference to the guidelines provided in this specification, or may be carried out according to generally accepted experimental manuals or conventional experimental conditions, or other experimental methods known in the art, or according to the conditions recommended by the relevant reagent or instrument manufacturers. In specific embodiments, unless otherwise specified, minor deviations within the weighing accuracy range are allowed for the measurement parameters involving raw material components; reasonable deviations due to instrument detection accuracy or operational accuracy are also allowed for parameters such as temperature and time.

[0069] All embodiments and comparative examples used the same raw materials: T700 grade carbon fiber / PEEK prepreg (initial width 150 mm) with a resin content of approximately 35%, slit into narrow strips with a target width of 6.35 mm.

[0070] 1. Sampling specifications: Sampling object: Samples are cut from the molded CF / PEEK composite laminate.

[0071] Sampling Location: Sampling should cover a representative area of ​​the component to assess in-plane uniformity. For flat or gently curving areas, a five-point grid sampling method is recommended: take one point (C) at the center of the component, and four points (N, S, E, W) at approximately 10% of the edge along the wire lay direction and perpendicular to the wire lay direction, for a total of five sampling points. For complex components, sampling should be taken at least in areas where non-uniformity is expected (such as areas with large curvature of the wire lay path, at the start / end of the stack) and in gently curving areas.

[0072] Sampling depth: Given that automated fiber placement components are usually laminated structures and the overall performance within and between layers is of concern, the sampling is a full-thickness sample that penetrates the entire thickness to reflect the average crystallization state of the component as a whole (including within and between layers).

[0073] Sample preparation: After obtaining the sample, 5-10 mg should be accurately weighed and placed in a DSC-specific crucible to ensure that the resin content is known or can be corrected by ablation.

[0074] 2. Testing Method: Differential scanning calorimetry (DSC) was used, and the tests were conducted strictly in accordance with the ISO 11357-3 standard.

[0075] Test procedure: Heating from 30°C to 400°C at a rate of 10°C / min under a nitrogen atmosphere. The enthalpy of fusion (ΔHm) of the first heating curve was used to calculate the true thermal history of the material.

[0076] 3. Quantitative criteria for determining "stable / uniform crystallinity": Accuracy (stability) judgment: Under the same process batch, the absolute deviation between the arithmetic mean of crystallinity (Xc_avg) measured at all sampling points and the preset target crystallinity value (Xc_target) should meet the following: |Xc_avg - Xc_target|≤ 1.5%.

[0077] Uniformity (consistency) judgment: The difference between the maximum and minimum crystallinity values ​​(range, R) of all sampling points on the same component (or representative components of the same batch) should satisfy: R ≤ 4%; more preferably, its standard deviation (σ) should satisfy: σ ≤ 1%. This standard is used to quantify "in-plane distribution deviation".

[0078] The formula for determining the crystallinity of PEEK is Xc(%) = (ΔHm / 130) × 100% / resin content (ΔHm0 is 130, ΔHm is the actual enthalpy value measured by DSC). For PEEK composite materials, the thermal history curve should be mainly studied based on the single-heating curve on the DSC curve.

[0079] Only components that simultaneously meet both of the above criteria can be considered to have achieved "precise, stable, and uniform control of crystallinity".

[0080] Example 1: Preparation of high crystallinity (≥35%) laminate Step 1: Raw material pretreatment and tension matching control The wide-width prepreg is slit under constant tension. The slitting tension is controlled at 10N, and the feed speed is 0.4m / s, resulting in a narrow strip with a width of 6.35mm ± 0.05mm. Subsequently, it is coiled under the control of a tension adaptive device, with the coiling tension set at 12N (a difference of 2N from the slitting tension) to ensure that the coils are tight and neat.

[0081] Step 2: Parametric tiling based on the collaborative model Install the filament spool into the automatic filament placement machine. Based on the high crystallinity target, the collaborative control model automatically selects and executes the core process parameters of the "low speed-high temperature-high pressure" paradigm: Placement temperature: 420℃ • Placement speed: 0.05 m / s • Placement pressure: 300N (applied by a silicone roller with a Shore A hardness of 70); Based on the above parameters, 12 layers are laid on a flat mold to prepare a laminated preform with a size of 300mm*300mm.

[0082] Step 3: Linked Programmable Cooling After the paving is completed, the precast structure is immediately moved to an insulated platform and kept at 150°C for 30 minutes. Then, a cooling program linked to the high crystallinity target is started to cool the component to room temperature at a slow cooling rate of 5°C / min.

[0083] Effect test: 1. Crystallinity test: A sample was taken from the center area of ​​the finished laminate and tested using a differential scanning calorimeter (DSC) according to the ISO11357-3 standard. The crystallinity was calculated to be 36%.

[0084] 2. Mechanical property testing: Interlaminar shear strength: Tested according to standard GB / T 30969-2014, the result is 95.3 MPa.

[0085] Bending performance: Three-point bending test was conducted according to standard GB / T 1449-2005. The bending strength was 1555 MPa and the bending modulus was 99 GPa.

[0086] Impact strength: A simply supported beam unnotched impact specimen was prepared according to GB / T 1043.1-2008, and the test result was 57.3 kJ / m. 2 Example 2: Preparation of medium crystallinity (target 25%-30%) laminate Except for the parameters described below, the rest of the process is the same as in Example 1.

[0087] Installation parameters: Temperature 400℃, speed 0.10 m / s, pressure 200N. Cooling regime: After heat preservation, cool at a rate of 8℃ / min.

[0088] Effect test: 1. Crystallinity: DSC test result is 26%.

[0089] 2. Mechanical properties: Interlaminar shear strength: 85.7 MPa.

[0090] Bending strength: 953 MPa, bending modulus: 85 GPa.

[0091] Impact strength: 75.7 kJ / m 2 .

[0092] Example 3: Preparation of low crystallinity (target 20%-25%) laminate Except for the parameters described below, the rest of the process is the same as in Example 1.

[0093] • Installation parameters: Temperature 380℃, speed 0.15 m / s, pressure 100N. Cooling regime: After heat preservation, cool at a rapid rate of 10℃ / min.

[0094] Effect test: 1. Crystallinity: DSC test result is 22%.

[0095] 2. Mechanical properties: Impact strength: 86.5 kJ / m 2 .

[0096] Bending strength: 702 MPa; Bending modulus: 69 GPa.

[0097] Interlaminar shear strength: 75.4 MPa.

[0098] Comparative Example To highlight the advantages of this invention, a comparative example is provided. The same raw materials and laying path are used as in the embodiment, but the process is as follows: Slitting and traying: The slitting tension fluctuates greatly, the traying tension is not fixed, and tension matching control is not performed.

[0099] Installation parameters: A common combination of fixed parameters used in AFP process is adopted: temperature 400℃, speed 0.10 m / s, pressure 200N.

[0100] Cooling method: After installation, allow it to cool naturally in the air (cooling rate is approximately 30℃ / min).

[0101] Effect test: Crystallinity: Crystallinity test results: Point C: 22.0%, Point N: 25.3%, Point S: 21.0%, Point E: 26.1%, Point W: 23.8%.

[0102] Uniformity analysis: Arithmetic mean (Xc_avg): (22.0+25.3+21.0+26.1+23.8) / 5 = 23.64%; Range (R): Maximum value (26.1%) - Minimum value (21.0%) = 5.1%; Standard deviation (σ): Calculated to be approximately 2.0%.

[0103] Conclusion: The crystallinity of Comparative Example 4 not only deviates significantly from any preset target in terms of average value (23.64%), but also exhibits extremely poor in-plane uniformity (R=5.1% > 4%, σ=2.0% > 1%), clearly displaying a "mosaic" distribution of crystallinity. This directly proves the fundamental defect of traditional processes in controlling crystallinity uniformity during narrow-band laying. The DSC test result was 22%, and when samples were taken from different locations on the same board, the results fluctuated between 21% and 26.1%, indicating poor uniformity.

[0104] Mechanical properties: interlaminar shear strength is 77.2 MPa (with a coefficient of variation of 12%), and impact strength is 87.7 kJ / m. 2 .

[0105] The main parameters of the products prepared according to Examples 1-3 and the comparative example are summarized as follows:

[0106] The performance test results above show that the actual crystallinity of Examples 1 to 3 prepared using the whole-process synergistic crystallinity control method of the present invention is highly consistent with the preset target crystallinity, and the in-plane distribution range is controlled within 1.3%, which is significantly better than the 5.1% of the comparative example. This indicates that the synergistic effect of tension stabilization control, temperature-speed-pressure synergistic control and programmed speed-controlled cooling can effectively suppress the spatial fluctuation of crystallinity during narrow strip laying and achieve uniform control of crystal structure.

[0107] Further analysis of the mechanical properties reveals that the interlaminar shear strengths of Examples 1-3 reached 95.3 MPa, 85.7 MPa, and 75.4 MPa, respectively, with coefficients of variation all below 3%, demonstrating good batch stability. In contrast, the interlaminar shear strength dispersion coefficient of the comparative example was as high as approximately 12%, indicating that traditional fixed-parameter processes are insufficient to guarantee the consistency of interlaminar properties in narrow-band CF / PEEK components. These results fully demonstrate that the present invention, through precise control of crystallinity, can simultaneously improve interfacial bonding quality and structural stability.

[0108] Meanwhile, the comparison of bending and impact properties shows that the embodiments corresponding to different crystallinity ranges exhibit a predictable controllable relationship between strength and toughness. High crystallinity embodiment 1 demonstrates excellent bending strength and modulus, medium crystallinity embodiment 2 achieves a balance between strength and toughness, and low crystallinity embodiment 3 exhibits high impact absorption capacity. In contrast, the comparative embodiments show unstable properties, further illustrating that the present invention can achieve directional design and stable realization of composite material properties according to design requirements.

[0109] In summary, the comparison results of Examples 1-3 and the comparative examples clearly show that the whole-process collaborative crystallinity control method proposed in this invention can not only achieve precise matching and in-plane uniform control of the target crystallinity, but also significantly reduce the dispersion of mechanical properties and improve the repeatability and reliability of the overall performance of the components, thereby effectively overcoming the technical defects of uncontrollable crystallinity and large performance fluctuations in the traditional narrow-band automatic fiber placement process.

[0110] Experiment Example 1: Validation under non-cooperative parameter combinations This comparative example aims to verify that when temperature (T) and pressure (P) are not coordinated with the layup rate (V), even if the target crystallinity can be achieved, serious failures will occur in other key properties.

[0111] Raw materials and pretreatment: Same as in Example 1.

[0112] Tile parameters (non-coordinated combination): • Fixed parameters: Installation temperature T = 400℃, installation pressure P = 200N. (These are common medium parameters) Variables: The laying speed V is set to 0.05 m / s (low speed), 0.10 m / s (medium speed), and 0.15 m / s (high speed).

[0113] Cooling regime: To maintain uniformity, the same medium-speed cooling (8°C / min) as in Example 2 was used.

[0114]

[0115] The results above show that, with fixed T and P, adjusting only the speed V can unidirectionally change the crystallinity, but at the cost of severely deteriorating other properties. The high dispersion of interlayer shear strength and the destruction of the filament morphology are direct evidence that "non-synergistic" process parameters lead to failure. This demonstrates the indispensability of the "temperature-speed-pressure synergistic control model" proposed in this invention for achieving balanced, stable, and reliable performance of narrowband CF / PEEK components.

[0116] Experiment Example 2: Verifying the effect of programmed cooling lock-in Raw materials and pretreatment: Same as in Example 1.

[0117] Application parameters: The synergistic parameters of Example 1 (high crystallinity target) are adopted in full (T=420℃, V=0.05 m / s, P=300N).

[0118] Cooling regime (key variable): After the tiling is completed, no heat preservation or programmed cooling is performed. Instead, the components are placed directly in the room temperature environment to cool naturally (measured average cooling rate >30℃ / min).

[0119]

[0120] The results above show that programmed cooling is the final key to achieving the preset crystallinity: without controlled slow cooling (5°C / min), the preset "high crystallinity tendency" in the laying stage cannot be transformed into an actual "high crystallinity structure". Natural cooling abruptly interrupts the crystallization process.

[0121] Programmed cooling is key to ensuring uniform and stable performance: uncontrollable natural cooling introduces new, random variables, leading to a deterioration in crystallinity uniformity (range increases from 1.3% to 3.5%) and a significant increase in the dispersion of mechanical properties (CV of ILSS increases from 2.0% to 8.0%).

[0122] The entire process is indispensable: S1 (stable input), S2 (cooperative preset), and S3 (linkage locking) of this invention form a closed-loop organic whole. The experiment shows that even if S1 and S2 execute perfectly, the absence of S3 will lead to the failure of the entire process, which in turn reinforces the creativity and necessity of the invention's core concept of "full-process collaboration".

[0123] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for automatically controlling the crystallinity of narrow-band CF / PEEK fiber placement, characterized in that, Includes the following steps: S1, tension stabilization control is implemented on the prepreg to ensure that it is in a stable supply state within a preset tension range before entering the laying process; S2, Perform the laying operation according to the target crystallinity. During the laying process, the laying parameters are matched and set according to the temperature T-speed V-pressure P coordinated control model, so that the material forms a crystallization trend corresponding to the target crystallinity during the laying stage, wherein: When the target crystallinity is ≥35%, the laying speed V is adjusted to the low speed end and V≤0.08 m / s, the laying temperature T is adjusted to the high temperature end and T≥410 ℃, and the laying pressure P is adjusted to the high pressure end and P≥250 N. When the target crystallinity is 25% to 30%, the laying speed V should be 0.08 m / s < V < 0.12 m / s, the laying temperature T should be 390 ℃ < T < 410 ℃, and the laying pressure P should be 150 N < P < 250 N. When the target crystallinity is ≥20% and <25%, the laying speed V is adjusted towards the high-speed end and V≥0.12 m / s is adopted; the laying temperature T is adjusted towards the near melting limit temperature or lower end and T≤390 ℃ is adopted; and the laying pressure P is adjusted towards the low-pressure end and P≤150 N is adopted. S3, implement programmed speed-controlled cooling of the completed part in conjunction with the target crystallinity to lock the crystalline structure formed during the laying stage; the cooling rate is negatively correlated with the target crystallinity.

2. The method according to claim 1, characterized in that, In step S1, the slitting tension is 8-12 N, the tray loading tension is 10-30 N, and the absolute value of the difference between the tray loading tension and the slitting tension is no greater than 5 N. Optionally, in step S1, the tension fluctuation of the prepreg is monitored and adjusted in real time to keep the tension fluctuation amplitude within ±2 N.

3. The method according to claim 1, characterized in that, In step S3, when the target crystallinity is ≥35%, the cooling rate is 3-5 °C / min; when the target crystallinity is 25-30%, the cooling rate is 7-8 °C / min; and when the target crystallinity is ≥20% and <25%, the cooling rate is 10-12 °C / min.

4. The method according to claim 1, characterized in that, In step S3, before the programmed speed-controlled cooling, the laid parts are subjected to heat preservation and homogenization treatment at 120-180 ℃ for 10-40 min.

5. The method according to any one of claims 1 to 4, characterized in that, In step S2, the collaborative control model uses the laying speed V as the dominant parameter to determine the heat treatment time, and dynamically matches and adjusts the laying temperature T and laying pressure P according to the laying speed V.

6. The method according to any one of claims 1 to 4, characterized in that, The programmed speed control cooling adopts either a linear cooling method or a stepped cooling method. Optionally, the programmed speed-controlled cooling is performed in a closed or semi-closed heating environment.

7. The method according to any one of claims 1 to 4, characterized in that, The width of the narrow-band CF / PEEK prepreg is 3–10 mm; Optionally, the resin content of the prepreg is 30% to 40%.

8. A narrow-band CF / PEEK automatic fiber placement crystallinity control system, characterized in that, The system includes: Target crystallinity setting module, parameter co-calculation module, layup control module, and cooling control module; The target crystallinity setting module is used to receive and store the target crystallinity parameters of the part to be formed; The parameter collaborative calculation module is used to generate a combination of paving process parameters corresponding to the target crystallinity based on the temperature T-speed V-pressure P collaborative control model. The laying control module is used to receive the laying process parameter combination output by the parameter co-calculation module, and control the automatic fiber placement equipment to perform the laying operation according to the laying temperature, laying speed and laying pressure, so that the material forms a preset crystallization trend during the laying stage; The cooling control module is used to receive the target crystallinity parameter and control the programmed speed cooling process of the part according to the target crystallinity parameter, so that the cooling rate matches the target crystallinity, thereby locking the crystalline structure formed in the laying stage. When the system is running, it performs the method described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer storage medium is used to store computer instructions, programs, code sets, or instruction sets, which, when run on a computer, enable the computer to perform the functions corresponding to the crystallinity setting module, parameter collaborative calculation module, tiling control module, and cooling control module in the system described in claim 8.

10. An electronic device, characterized in that, include: One or more processors; as well as A computer-readable storage medium for storing computer instructions, programs, code sets, or instruction sets, which, when executed on a computer, cause the one or more processors to perform the functions corresponding to the crystallinity setting module, parameter co-calculation module, tiling control module, and cooling control module in the system of claim 8.

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