Laser-assisted in-situ forming process and device protected by high-temperature inert gas

Abstract

The invention relates to the technical field of automatic laying of composite materials, in particular to a laser-assisted in-situ forming process and device protected by high-temperature inert gas, and the process comprises the following steps: supplying a prepreg tape to a laying point; the laying points are heated through laser; an inert gas protection cover is arranged on the periphery of the laying point, heated inert gas is supplied, a local inert atmosphere is formed, and meanwhile the inert gas forms composite heating through convective heat transfer and laser radiation; and under the covering of the protective cover, the in-situ consolidation is realized through the compaction of the compaction roller. The device comprises a laying head module, a laser heating unit, an inert gas protection cover and an inert gas supply unit. A stable high-temperature inert protection environment is formed in a laser heating and compacting area, the oxidation and thermal aging risks of a thermoplastic matrix are reduced, the heating efficiency is improved, the laying speed is increased, control over a temperature field is achieved through partitioned gas supply, and therefore the forming quality and process stability of a composite material component are improved.

Description

Technical Field

[0001] This invention relates to the field of automated composite material laying technology, and in particular to a laser-assisted in-situ forming process and apparatus under high-temperature inert gas protection. Background Technology

[0002] Continuous fiber reinforced thermoplastic composites (CFRTPs), such as continuous carbon fiber reinforced polyetheretherketone (CF / PEEK) and polyphenylene sulfide (CF / PPS), are used in aerospace, new energy vehicles, and high-end equipment due to their high specific strength, high specific stiffness, excellent impact resistance, weldability, and recyclability. Laser-assisted automated layup technology uses a laser beam to rapidly and locally heat the prepreg tape at the layup point, melting the thermoplastic matrix. Subsequent pressure from compaction rollers achieves interlayer welding and consolidation, offering advantages such as eliminating the need for autoclaves and shortening the manufacturing cycle.

[0003] However, existing laser-assisted automated layup technologies are typically performed in open environments, which presents several drawbacks in practice: First, thermoplastic resin matrices (such as PEEK and PPS) are highly susceptible to oxidation, thermal degradation, or molecular chain breakage when exposed to air at the high temperatures generated by the laser (often exceeding their melting point). Second, the single laser radiation heating method is easily affected by factors such as surface reflection of the prepreg tape and environmental convection heat dissipation, especially when laying up at high speeds or processing curved components, making it difficult to quickly and uniformly maintain the temperature at the layup point within the optimal melting window. Third, existing technologies that suppress oxidation often employ methods such as purging large areas of the processing area with inert gases (such as nitrogen, argon, carbon dioxide, helium, and their mixtures). However, these methods result in rapid gas diffusion, high consumption, and unstable protective atmospheres, leading to high operating costs and difficulty in creating and maintaining an effective low-oxygen environment at high-speed moving layup points. Currently, no publicly reported methods exist in the field of automated thermoplastic composite material layup that utilize localized inert gas protection to prevent thermoplastic material oxidation, increase peak laser power, and broaden the process window.

[0004] Therefore, there is an urgent need for an in-situ forming process and device that can provide stable and efficient high-temperature inert gas protection for the laying point while simultaneously heating with laser, and can achieve composite heat input and zoned temperature control. Summary of the Invention

[0005] The purpose of this invention is to provide a laser-assisted in-situ forming process and apparatus under high-temperature inert gas protection, thereby solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides a laser-assisted in-situ forming process under high-temperature inert gas protection, comprising the following steps: S1. Material supply and laying: Supply continuous fiber-reinforced thermoplastic and pull the prepreg tape to the laying point; S2. Laser-assisted heating: Laser is used to heat the prepreg tape in the laying area so that the thermoplastic matrix reaches a molten or highly elastic state and meets the requirements of in-situ welding. S3, Inert Gas Protection and Composite Heating: An inert gas protection cover is set around the laying point. The inert gas protection cover covers an area including at least the laser heating zone and the compaction zone. Heated inert gas is supplied into the inert gas protection cover to form a local inert atmosphere covering the laying point. The inert gas forms composite heating with the laser heating in S2 through convection heat transfer. S4. Compaction and In-situ Consolidation: Under the cover of the inert gas protective cover, the prepreg tape that has been composite heated is compacted by a compaction roller to achieve in-situ consolidation.

[0007] Preferably, in S3, the inert gas is nitrogen, argon, carbon dioxide, helium, or a mixture thereof.

[0008] Preferably, in S3, the inert gas protective cover is provided with at least two independent temperature control zones along the laying direction, and the temperature of each zone is controlled by independently adjusting the temperature or flow rate of the inert gas to each zone.

[0009] Preferably, the temperature control zone includes a melt compaction zone and at least one of a preheating zone and an initial cooling zone, wherein the temperature of the inert gas supplied to the melt compaction zone is controlled to be higher than the ambient temperature and within the range of the thermoplastic matrix melting temperature Tm ± 30°C.

[0010] Preferably, it also includes S5: real-time monitoring of the temperature of the laying point, and based on the deviation between the monitored temperature and the target temperature, coordinating the adjustment of the power of the laser and the temperature and flow rate of the inert gas; It also includes S6: recovering the inert gas discharged from the inert gas protective cover, processing it, and then resupplying it to S3 for use.

[0011] A laser-assisted in-situ forming device with high-temperature inert gas protection includes a laying head module, a laser heating unit, an inert gas protective cover, and an inert gas supply unit. The laying head module includes a laying head body, a feeding guide mechanism for conveying continuous fiber-reinforced thermoplastic prepreg tape, and a compaction roller installed at the front end of the module. The laser heating module is installed on one side of the laying head body, and the laser beam emitted by it is directed at the laying point area in front of and below the compaction roller; The inert gas protective cover is fixedly installed around the laying point and fixedly connected to the laying head body. The wall of the inert gas protective cover is provided with an air inlet and an air outlet that are connected to the inert gas supply unit, and an opening is provided at the position corresponding to the laser beam path so that the laser beam passes through and is focused on the laying point. The compaction roller is installed inside the inert gas protective cover.

[0012] Preferably, the wall of the inert gas protective cover near the laser heating unit has an opening, and the lower edge of the inert gas protective cover is surrounded by at least one of a flexible sealing skirt, a labyrinth gap structure, or a follow-fit structure to reduce inert gas leakage loss.

[0013] Preferably, the interior of the inert gas protective cover is divided into at least two independent chambers by a partition structure. Each independent chamber is connected to the inert gas supply unit through an independent gas supply branch, and each gas supply branch is equipped with a flow controller and a gas heater.

[0014] Preferably, it also includes a gas recovery and circulation system, which is connected to the outlet of the inert gas protective cover and the inlet of the inert gas supply unit through a pipeline. The pipeline is equipped with a filter for removing impurities and a circulation pump for driving gas circulation.

[0015] Preferably, it also includes a temperature monitoring and control system, which includes a controller and an infrared thermal imager. The infrared thermal imager is installed below the laser heating unit and is used to acquire in real time the temperature field image of the area where the inert gas protective cover is laid. The controller is connected to the infrared thermal imager, the laser heating unit and the inert gas supply unit respectively. The controller is configured to generate and output control signals for synchronously adjusting the laser output power and the temperature and flow rate of the inert gas leading to the inert gas shield, based on a comparison between the temperature information fed back by the infrared thermal imager and preset process parameters. The laser heating unit can be replaced with a xenon lamp or an infrared heater.

[0016] Therefore, this invention provides a laser-assisted in-situ forming process and apparatus with high-temperature inert gas protection, which has the following beneficial effects: By forming a stable local inert atmosphere in the laser heating zone and compaction zone through the inert gas protective cover, the risk of oxidative degradation of the thermoplastic resin matrix during high-temperature processing is reduced, ensuring the chemical stability of the molten interface, thereby improving the interfacial bonding strength and consistency, reducing the probability of internal defects such as porosity, and obtaining composite material components with more stable quality. Because oxidation is effectively controlled, the allowable fluctuation range of key parameters such as laser power, layup speed, and processing temperature is expanded, making the process more tolerant to environmental changes or complex paths, and improving the robustness of the layup process.

[0017] After the heated inert gas enters the protective cover, it not only provides a protective atmosphere, but also directly transfers heat to the prepreg tape or the laid layer through convection heat transfer. This combined heating with laser radiation allows for a reduction in the required peak laser power or an increase in the laying speed at the same laser power while achieving the same melting effect, thus improving laying efficiency.

[0018] By dividing the interior of the inert gas protective cover into multiple temperature-controlled zones (preheating zone, melting and compaction zone, and initial cooling zone) and independently adjusting the temperature and flow rate of the inert gas in each zone, the temperature gradient along the laying path can be controlled. This allows the material to soften sufficiently in the preheating zone, melt and compact in the melting and compaction zone, and cool steadily in the initial cooling zone, which helps reduce thermal stress, suppress warping deformation, and improve forming accuracy and dimensional stability.

[0019] By adopting a semi-enclosed protective cover and a flexible sealing structure at its lower edge, the leakage of inert gas into the environment is reduced. At the same time, the gas recovery and circulation system can filter and purify the exhaust gas for reuse, reducing inert gas consumption and saving production costs. Attached Figure Description

[0020] Figure 1 This is an overall schematic diagram of a laser-assisted in-situ forming device protected by a high-temperature inert gas according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of the inert gas protective cover in Embodiment 1 of the present invention; Figure 3 This is a flow chart of a laser-assisted in-situ forming process with high-temperature inert gas protection according to Embodiment 1 of the present invention; Figure Labels 1. Laying head module; 101. Laying head body; 102. Feeding and guiding mechanism; 2. Prepreg tape reel; 3. Prepreg tape; 4. Wire cutting device; 5. Semiconductor laser; 6. Inert gas protective cover; 601. Air inlet; 602. Air outlet; 603. Opening; 7. Preheating zone; 8. Melting and compaction zone; 9. Primary cooling zone; 10. Flexible sealing skirt; 11. Infrared thermal imager. Detailed Implementation

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] Example 1 This embodiment uses continuous carbon fiber reinforced polyphenylene sulfide (CF / PPS) prepreg tape as an example to illustrate in detail the implementation process of the present invention's process and apparatus.

[0025] like Figure 1-3 As shown, the substrate used in this embodiment is unidirectional carbon fiber reinforced PPS prepreg tape (CF / PPS), with a width of 6.35 mm and a thickness of 0.18 mm, and a flat steel mold is used as the laying base. A schematic diagram of the device used in this embodiment is shown below. Figure 1 As shown, the device includes a laying head module 1, a laser heating unit, an inert gas protective cover 6, an inert gas supply unit, a temperature monitoring and control system, and a gas recovery and circulation system. The laying head module 1 serves as the execution terminal and is connected to the end of a six-axis robot arm via a mounting flange. The movement path of the robot arm is controlled by the robot program.

[0026] The laying head module 1 includes a laying head body 101, a feeding guide mechanism 102, and a compaction roller. The feeding guide mechanism 102 includes a prepreg reel 2 and a series of guide rollers, used to continuously and smoothly transport the prepreg tape from the reel to the laying point. A pneumatic or electric wire cutting device 4 is installed on the prepreg tape path upstream of the compaction roller at the end of the feeding guide mechanism 102, used to quickly and neatly cut the prepreg tape when the laying path ends or when the material needs to be changed. The compaction roller is a 30mm diameter roller with a surface coated with high-temperature resistant silicone, installed at the bottom end of the laying head body 101.

[0027] The laser heating unit is fixedly installed on the side of the laying head module 1. The laser beam is transmitted through an optical fiber and a collimating and focusing lens, and is transmitted at an angle of approximately 45° to the base plane. It is focused on the engagement point between the compaction roller and the mold when the roller presses down, and the beam area covers the width of the prepreg tape. In this embodiment, the laser heating unit is a semiconductor laser 5, but it can also be replaced with a xenon lamp or an infrared heater.

[0028] The inert gas protective cover 6 is made of high-temperature resistant stainless steel and is fixedly connected to the lower part of the laying head body 101. It completely surrounds the compaction roller and covers the laying area in front of it, and moves synchronously with the laying head. In this embodiment, the inert gas protective cover 6 is a semi-enclosed box structure. An opening 603 is provided on the side wall of the protective cover facing the laser beam incident path, allowing the laser beam to pass through the protective cover and act on the laying point. The internal space of the inert gas protective cover 6 is provided with three independent chambers along the laying direction through partitions, namely the preheating zone 7, the melting and compaction zone 8, and the initial cooling zone 9. Each independent chamber is connected to the inert gas supply unit through an independent gas supply branch. Each gas supply branch is equipped with a flow controller and a gas heater to realize independent control of the gas flow and temperature of each zone.

[0029] An air inlet 601 is provided on the side wall of each section corresponding to the protective cover, and an exhaust port is provided on the opposite side wall. A high-temperature resistant silicone flexible sealing skirt 10 is installed on the lower edge of the inert gas protective cover 6. During installation, this skirt slightly contacts or is very close to the mold surface, and adapts to the curvature of the surface. Its main function is to greatly reduce the leakage of inert gas from the cover to the outside and maintain the stability of the local atmosphere.

[0030] The temperature monitoring and control system includes an infrared thermal imager 11 and a controller. The infrared thermal imager 11 is mounted below the semiconductor laser 5 to ensure that its field of view can completely cover the temperature field from the preheating zone 7 to the initial cooling zone 9. In this embodiment, the controller is an industrial PLC, which receives the temperature data of each zone fed back by the infrared thermal imager 11 in real time (the temperature of the preheating zone 7 is...). The temperature of the molten compaction zone 8 is and the temperature of the initial cooling zone 9 The target temperatures are compared with those preset by the user (target temperature T1 for preheating zone 7, target temperature T2 for melt compaction zone 8, and target temperature T9 for initial cooling zone 9). ), The infrared thermal imager 11 continuously monitors the temperature of each zone and compares it with the target temperature of the corresponding zone. , and for: ; ; ; In the formula, This represents the difference between the measured temperature of the preheating zone and the target temperature of the preheating zone. This represents the difference between the measured temperature of the molten compaction zone and the target temperature of the molten compaction zone. This represents the difference between the measured temperature of the primary cooling zone and the target temperature of the primary cooling zone. If Δ ≥30℃, Δ ≥30℃, Δ When the temperature is ≥30℃, the controller uses a collaborative algorithm to synchronously adjust the laser power and the temperature or flow rate of the gas introduced into the corresponding zone, so that the temperature is close to the target set value.

[0031] The gas recovery and circulation system includes a circulation pump, a filter, and a gas storage tank. The inlet of the circulation pump is connected to the outlet 602 of the inert gas protective cover 6 through a pipeline. The discharged gas passes through the filter in sequence to remove any resin volatile condensate particles that may be carried. The filtered gas is sent into the gas storage tank and can then be recirculated back into the main gas supply pipeline.

[0032] This embodiment uses continuous carbon fiber reinforced polyphenylene sulfide (CF / PPS) prepreg tape as the processing object, and the specific process flow is as follows: Install the CF / PPS prepreg tape reel 2 onto the laying head feeding mechanism, and thread the tape through the guide roller and the wire cutting device 4 to the point where the compaction roller engages with the substrate.

[0033] And based on the characteristics of PPS resin (glass transition temperature) ≈90℃, melting temperature (≈280℃), set the following process parameters on the controller's human-machine interface: laying path trajectory and laying speed are 20mm / s; laser starting power is 240W; compaction roller pressure is 300N; set the target temperature of the melting compaction zone 8 to 320℃; and set the temperature and flow rate parameters of the inert gas introduced into each zone: preheating zone 7 (gas temperature 100℃, flow rate 10L / min), melting compaction zone 8 (gas temperature 280℃, flow rate 15L / min), and initial cooling zone 9 (gas temperature 90℃, flow rate 8L / min).

[0034] The robotic arm drives the laying head module 1 to start moving along the preset trajectory, and the feeding mechanism works synchronously to convey the prepreg tape with constant tension; Argon gas at 100°C is introduced into the preheating zone 7 to preheat the prepreg tape to be introduced, and at the same time, it begins to displace the air in the area. The laser beam irradiates the laying point, providing the main heat source. Meanwhile, high-temperature argon gas at 280°C is continuously introduced into the melting and compaction zone 8 to achieve two core functions: first, to form and maintain a stable low-oxygen inert environment to inhibit the oxidation and thermal degradation of PPS at high temperatures; second, the high-temperature gas directly heats the surface of the prepreg tape and the laid layer through convection heat transfer, and combines with laser radiation for heating, thereby improving thermal efficiency.

[0035] Infrared thermal imager 11 continuously monitors the temperature of each zone, and the controller adjusts the temperature based on the measured temperature of the melt compaction zone 8 (e.g., =285) and target temperature ( To correct the deviation of 320, a collaborative algorithm is used to simultaneously fine-tune the process by increasing the laser power (e.g., to 250W) and slightly increasing the gas temperature or flow rate in the area, so that the temperature quickly returns to the set value.

[0036] Under inert atmosphere protection and precise temperature control, the prepreg tape, which has reached a molten state, is bonded to the mold or to the prepreg tape layer already laid on the mold surface under the pressure of 300N of the compaction roller, achieving high-quality in-situ consolidation.

[0037] After consolidation, the layers enter the initial cooling zone 9, where they begin to cool slowly and controllably under the action of a low-temperature argon gas flow at 90°C, which helps to reduce residual thermal stress and warping deformation.

[0038] The gas discharged from the outlet 602 is recycled and filtered before being sent to the gas storage tank, where it can be recirculated back into the main gas supply line. When a single laying path ends, the controller commands the wire cutting device 4 to cut the prepreg tape.

[0039] It should be noted that although this invention is described using a laser-assisted automatic layup process and device as an example, it forms a stable high-temperature inert environment through a local inert gas protective cover and adopts a process concept of composite heating and zoned temperature control using radiation heating and high-temperature gas convection heat transfer. This concept can be applied to other in-situ consolidation additive manufacturing processes of continuous fiber reinforced thermoplastic composite materials, such as continuous fiber 3D printing processes assisted by lasers or other radiation heat sources. It aims to solve the problems of easy high-temperature oxidation of thermoplastic matrix, difficulty in temperature control, and unstable forming quality in such processes.

[0040] Example 2 This embodiment aims to demonstrate that by selecting different types of inert gases and adjusting their parameters, the present invention can flexibly adapt to different process requirements, further expanding its application scope.

[0041] The same apparatus as in Example 1 was used, except that the protective gas was replaced with carbon dioxide (CO2) instead of argon, and the laser power was set to 320W.

[0042] Carbon dioxide has a lower thermal conductivity at room temperature and pressure (approximately 0.017 W / (m·K)) than air (approximately 0.026 W / (m·K)). CO2 at 200°C and a low flow rate (10 L / min) is introduced into the molten compaction zone 8. Due to the low thermal conductivity of CO2, its convective heat dissipation effect is weak at low flow rates, primarily serving as thermal insulation (low flow rate insulation). Experimental results show that when using the same 320 W laser power for placement as in an open environment, the placement point temperature is increased by 30-50°C in this mode. This allows for sufficient melting of the material without increasing or even decreasing the laser power. This provides a new solution for processing materials with low laser absorption or in scenarios where laser heat input needs to be reduced to lower energy consumption and equipment costs, thus widening the lower limit of the process window.

[0043] When the carbon dioxide flow rate is increased (20 L / min), although its thermal conductivity remains unchanged, the forced convection effect of the gas is significantly enhanced. The high-speed flowing gas continuously carries away heat from the surface of the placement point, and its overall cooling capacity increases with the flow rate (high-flow-rate cooling). Experimental results show that the temperature at the placement point is reduced by 20-50°C compared to the open environment. This prevents resin overheating and decomposition caused by excessively high laser power settings or excessively slow placement speeds, thereby widening the upper limit of the process window.

[0044] This embodiment demonstrates that the present invention can meet the processing requirements of different heat-sensitive resins (for example, using a high-flow cooling mode for materials that need to avoid overheating and a low-flow heat preservation mode for materials that need to be fully melted), or optimize quality and efficiency by fine-tuning parameters in the processing of the same material, which enhances the adaptability and robustness of the process of the present invention.

[0045] Comparative Example 1 This comparative example aims to demonstrate that, even with the same process parameters as in Example 1, a high-quality layup cannot be achieved in an open environment without inert gas protection. Under the same conditions of CF / PPS prepreg material, layup speed (20 mm / s), laser power (240 W), and compaction pressure (300 N), layup in an open environment without inert gas protection was performed as a comparative example. The entire layup process was carried out directly in the exposed environment.

[0046] Infrared thermal imager monitoring showed that in an open environment, due to natural convection cooling, changes in surface reflectivity, and the lack of auxiliary heat source compensation, the temperature fluctuation at the deployment point was extremely drastic. The instantaneous temperature fluctuated rapidly within a wide range of 250℃ to over 400℃, and could not be stabilized at the preset temperature of around 320℃.

[0047] During the laying process, it can be observed that the surface of the prepreg tape near the laying point becomes darker and is accompanied by a slight fumes. This is a direct manifestation of the thermo-oxidative aging of PPS resin in a high-temperature and oxygen-rich environment.

[0048] The molded laminate was inspected: In terms of appearance and microstructure, the sample surface showed uneven coloring and visible localized burn marks. Metallographic microscopy analysis revealed a porosity as high as 3.5%, significantly higher than the 0.8% in Example 1. The pores were mostly irregularly shaped and distributed at the interlayer interfaces, a result of changes in viscosity, decreased fluidity, and increased volatile matter after the molten resin oxidized.

[0049] Comparative Example 2 This comparative example aims to illustrate that when the melting effect or speed is improved simply by increasing the laser power, more serious problems will arise in an open environment. In this comparative example, except that the laser power is adjusted to 320W (the same laser power setting as in Example 2), all other conditions are exactly the same as in Comparative Example 1 (open environment, no protection). This power is intended to simulate the situation where energy input is increased in pursuit of higher layup efficiency or processing of thicker materials.

[0050] During the laying process, infrared monitoring showed that the instantaneous highest temperature at the laying point easily exceeded 500℃, and even approached 570℃. This is far higher than the melting temperature (280℃) of PPS and its thermal decomposition initiation temperature. The oxidation phenomenon was more obvious and severe than that of Comparative Example 1, the surface quality of the molded component was worse, and the interlaminar shear strength of the final sample was even lower than that of Comparative Example 1, and the porosity was not improved.

[0051] Comparative Examples 1 and 2 confirmed that oxidative degradation of the thermoplastic matrix in an open environment is one of the fundamental causes of weakened interfacial bonding and performance dispersion. This invention reduces the risk of high-temperature oxidative degradation by introducing a high-temperature inert gas protective shield and its control system. The comparative examples show that in an open environment, the adjustment range of process parameters (such as laser power) is very small: too low a power (240W) results in unstable temperature and insufficient melting; slightly higher a power (320W) immediately poses a risk of overheating and oxidation. The embodiments of this invention demonstrate that under inert gas protection, the system can operate stably over a wider range of laser power and layup speed, improving the robustness and adaptability of the process.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A laser-assisted in-situ forming process under high-temperature inert gas protection, characterized in that, Includes the following steps: S1. Material supply and laying: Supply continuous fiber-reinforced thermoplastic and pull the prepreg tape to the laying point; S2. Laser-assisted heating: Laser is used to heat the prepreg tape in the laying area so that the thermoplastic matrix reaches a molten or highly elastic state and meets the requirements of in-situ welding. S3, Inert Gas Protection and Composite Heating: An inert gas protection cover is set around the laying point. The inert gas protection cover covers an area including at least the laser heating zone and the compaction zone. Heated inert gas is supplied into the inert gas protection cover to form a local inert atmosphere covering the laying point. The inert gas forms composite heating with the laser heating in S2 through convection heat transfer. S4. Compaction and In-situ Consolidation: Under the cover of the inert gas protective cover, the prepreg tape that has been composite heated is compacted by a compaction roller to achieve in-situ consolidation.

2. The laser-assisted in-situ forming process with high-temperature inert gas protection according to claim 1, characterized in that: In S3, the inert gas is nitrogen, argon, carbon dioxide, helium, or a mixture thereof.

3. The laser-assisted in-situ forming process with high-temperature inert gas protection according to claim 2, characterized in that: In S3, at least two independent temperature control zones are provided inside the inert gas protective cover along the laying direction. The temperature or flow rate of the inert gas to each zone is adjusted independently to achieve temperature control of each zone.

4. The laser-assisted in-situ forming process with high-temperature inert gas protection according to claim 3, characterized in that: The temperature control zone includes a melt compaction zone and at least one of a preheating zone and an initial cooling zone, wherein the temperature of the inert gas supplied to the melt compaction zone is controlled to be higher than the ambient temperature and within the range of the thermoplastic matrix melting temperature Tm ± 30°C.

5. The laser-assisted in-situ forming process with high-temperature inert gas protection according to claim 1, characterized in that: It also includes S5: real-time monitoring of the temperature at the laying point, and based on the deviation between the monitored temperature and the target temperature, coordinating the adjustment of the laser power and the temperature and flow rate of the inert gas; It also includes S6: recovering the inert gas discharged from the inert gas protective cover, processing it, and then resupplying it to S3 for use.

6. A laser-assisted in-situ forming apparatus under high-temperature inert gas protection, employing the laser-assisted in-situ forming process under high-temperature inert gas protection as described in any one of claims 1-5, characterized in that: It includes a laying head module, a laser heating unit, an inert gas protective cover, and an inert gas supply unit. The laying head module includes a laying head body, a feeding guide mechanism for conveying continuous fiber-reinforced thermoplastic prepreg tape, and a compaction roller installed at the front end of the module. The laser heating module is installed on one side of the laying head body, and the laser beam emitted by it is directed at the laying point area in front of and below the compaction roller; The inert gas protective cover is fixedly installed around the laying point and fixedly connected to the laying head body. The wall of the inert gas protective cover is provided with an air inlet and an air outlet that are connected to the inert gas supply unit, and an opening is provided at the position corresponding to the laser beam path so that the laser beam passes through and is focused on the laying point. The compaction roller is installed inside the inert gas protective cover.

7. The laser-assisted in-situ forming device with high-temperature inert gas protection according to claim 6, characterized in that: An opening is provided on the wall of the inert gas protective cover near the laser heating unit. The lower edge of the inert gas protective cover is surrounded by at least one of a flexible sealing skirt, a labyrinth gap structure, or a follow-fit structure to reduce inert gas leakage.

8. The laser-assisted in-situ forming device with high-temperature inert gas protection according to claim 7, characterized in that: The interior of the inert gas protective cover is divided into at least two independent chambers by a partition structure. Each independent chamber is connected to the inert gas supply unit through an independent gas supply branch. Each gas supply branch is equipped with a flow controller and a gas heater.

9. A laser-assisted in-situ forming device protected by a high-temperature inert gas according to claim 6, characterized in that: It also includes a gas recovery and circulation system, which is connected to the outlet of the inert gas protective cover and the inlet of the inert gas supply unit through a pipeline. The pipeline is equipped with a filter for removing impurities and a circulation pump for driving gas circulation.

10. A laser-assisted in-situ forming device protected by a high-temperature inert gas according to claim 6, characterized in that: It also includes a temperature monitoring and control system, which includes a controller and an infrared thermal imager. The infrared thermal imager is installed below the laser heating unit and is used to acquire temperature field images of the laying point area inside the inert gas protective cover in real time. The controller is connected to the infrared thermal imager, the laser heating unit and the inert gas supply unit respectively. The controller is configured to generate and output control signals for synchronously adjusting the laser output power and the temperature and flow rate of the inert gas leading to the inert gas shield, based on a comparison between the temperature information fed back by the infrared thermal imager and preset process parameters. The laser heating unit can be replaced with a xenon lamp or an infrared heater.

Images