Thermoplastic resin-based carbon fiber composite tube and three-dimensional hot bending forming method thereof

Abstract

The invention belongs to the technical field of composite material forming, and particularly relates to a thermoplastic resin-based carbon fiber composite tube and a three-dimensional hot bending forming method thereof. Winding the thermoplastic resin-based prepreg for a plurality of layers, coating a nano modifier between the layers, and drying to obtain a pipe; acquiring melting temperature and crystallization temperature information of the pipe; according to the target bending angle and the pipe material characteristics, a traction angle set value of the three-dimensional hot bending device is obtained; determining an infrared radiation wavelength set value and a power density set value of the three-dimensional thermal bending device; the method comprises the following steps: putting a pipe into a three-dimensional hot bending device, matching the three-dimensional hot bending device to a traction angle set value, an infrared radiation wavelength set value and a power density set value, pulling the pipe at a melting temperature for hot bending, and then carrying out gradient cooling on the pipe after hot bending to obtain the thermoplastic resin-based carbon fiber composite pipe. And high-quality bending forming of the thermoplastic resin-based carbon fiber composite tube can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming, and in particular relates to a thermoplastic resin-based carbon fiber composite tube and a three-dimensional hot bending forming method thereof. Background Art

[0002] In the fields of aerospace, new energy vehicles, and high-end equipment manufacturing, there is a growing demand for lightweight and high-strength composite pipes. Fiber-reinforced thermoplastic composite pipes, with their excellent specific strength, corrosion resistance, and customizability, are gradually replacing traditional metal pipes and are widely used in key scenarios such as fuel delivery pipelines, high-voltage battery thermal management systems, and fluid transmission components. However, existing composite pipe bending forming technologies have significant bottlenecks: Traditional heating processes (such as induction heating or hot air circulation) result in low energy utilization (<50%) and uneven temperature field distribution (fluctuations >±10°C) due to the non-conductive properties of composite materials and differences in the heat absorption properties of the matrix. Conventional two-dimensional bending or push bending forming technologies cannot achieve complex three-dimensional spatial curvature, and the fiber-resin interface is prone to slip and delamination due to shear stress during the forming process. The dynamic control of the crystallinity of the thermoplastic matrix lacks a precise model, resulting in large discrete mechanical properties (bending strength deviation >15%).

[0003] Although the existing 3D free bending technology can realize the spatial bending forming of metal pipes, it has the following key defects: (1) It cannot adapt to the dimensional changes caused by temperature gradients during hot bending (such as curvature offset caused by differences in thermal expansion coefficients >8%); (2) The severe friction between the tube blank and the fixture during advancement (friction coefficient >0.3) can easily damage the surface functional coating (such as the anti-corrosion coating peeling rate >15%), affecting the service life of the pipe fittings; (3) The process is only applicable to metal materials that do not require quenching, and cannot meet the rapid phase change control requirements required for thermoplastic resin-based carbon fiber composite pipes (such as the control deviation of thermoplastic matrix crystallinity >10%). Summary of the Invention

[0004] In response to the above-mentioned problems existing in the prior art, the present invention provides a thermoplastic resin-based carbon fiber composite tube and a three-dimensional hot bending forming method thereof, which can achieve high-quality bending forming of the thermoplastic resin-based carbon fiber composite tube.

[0005] To achieve the above-mentioned purpose, the technical solution provided by the present invention is as follows:

[0006] In a first aspect, the present application provides a three-dimensional hot bending forming method for a thermoplastic resin-based carbon fiber composite tube, comprising:

[0007] Thermoplastic resin-based prepreg is wound into several layers and a nano-modifier is applied between the layers and dried to obtain a pipe;

[0008] Obtain the melting temperature and crystallization temperature information of the pipe;

[0009] According to the target bending angle and the material properties of the pipe, the pulling angle setting value of the three-dimensional hot bending device is obtained;

[0010] According to the pipe material, the infrared radiation wavelength setting value of the three-dimensional thermal bending device is obtained;

[0011] According to the melting temperature and wall thickness of the pipe, the power density setting value of the three-dimensional hot bending device is obtained;

[0012] The tube is placed in a three-dimensional hot bending device, and the three-dimensional hot bending device is matched to the pulling angle setting value, the infrared radiation wavelength setting value and the power density setting value. The tube is pulled at the melting temperature for hot bending, and then the hot-bent tube is gradient cooled to obtain the thermoplastic resin-based carbon fiber composite tube.

[0013] Optionally, determining a set value of a pulling angle of the three-dimensional thermal bending device according to a target bending angle and material properties of the pipe includes:

[0014] Initialize the values ​​of α and β, where α and β are the first and second weight coefficients, respectively. Then, execute the following loop until the absolute value of the difference between the actual bending angle and the target bending angle is less than 3°. Output the set value of the traction angle for the last iteration:

[0015] Obtain the interfacial shear strength and resin melt viscosity of the pipe;

[0016] The pulling angle setting value is calculated based on α, β, the interface shear strength of the pipe and the viscosity of the resin melt;

[0017] Conduct hot bending test on pipes according to the set value of traction angle to obtain the actual bending angle;

[0018] Calculating the absolute value of the difference between the actual bending angle and the target bending angle;

[0019] If the absolute value of the difference between the actual bending angle and the target bending angle is greater than or equal to 3°, the values ​​of α and β are dynamically adjusted.

[0020] Optionally, the calculation of the set value of the pulling angle according to α, β, the interfacial shear strength of the pipe and the resin melt viscosity includes:

[0021] ,

[0022] ,

[0023] ;

[0024] in, is the interfacial shear strength of the pipe; is the ideal interface strength set; is the resin melt viscosity of the pipe; The theoretical resin viscosity is set; satisfy:( ), , .

[0025] Optionally, the step of drawing the pipe at the melting temperature for hot bending comprises:

[0026] Initialize the output power of the three-dimensional heat bending device. The three-dimensional heat bending device heats the pipe with the output power and then performs the following cycle until the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is less than 0.5°C. Then, the pipe is pulled for heat bending:

[0027] Obtain the surface temperature of the pipe and calculate the absolute value of the difference between the surface temperature of the pipe and the melting temperature of the pipe;

[0028] If the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is greater than or equal to 0.5°C, obtain the pipe's thermal diffusivity, specific heat capacity, thermal conductivity, and the change in temperature deviation per unit time;

[0029] The power adjustment amount and the adjusted output power are obtained according to the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe.

[0030] Optionally, the power adjustment amount and the adjusted output power are obtained according to the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe, wherein the calculation formulas of the power adjustment amount ΔP and the adjusted output power P are as follows:

[0031] ,

[0032] P=P0+∆P;

[0033] Among them, the proportional coefficient , is the thermal diffusivity of the pipe (mm² / s); the integral coefficient , is the specific heat capacity (J / KG·K); differential coefficient , γ is the thermal conductivity (W / m·K), P0 is the output power of the three-dimensional thermal bending device when measuring the temperature of the pipe, e is the difference between the surface temperature of the pipe and the melting temperature of the pipe during temperature measurement, Δe is the change in temperature deviation per unit time, Δe= , e0 is the difference between the pipe surface temperature and the melting temperature of the pipe during the last temperature measurement, and Δt is the time interval between the two temperature measurements.

[0034] Optionally, determining the power density setting value of the three-dimensional heat bending device according to the melting temperature and wall thickness of the pipe includes:

[0035] Obtain the pipe wall thickness and melting temperature, and calculate the power density setting value using the following formula:

[0036] Power density = .

[0037] Optionally, the preparation of the nanomodifier includes the following method: dispersing nanoparticles in a solvent and adding a surfactant to obtain the nanomodifier; the nanoparticles are one or more of silicon carbide, silicon dioxide or carbon nanotubes; preferably, the mass fraction of nanoparticles in the nanomodifier is 0.3~2.0 wt%, and the mass fraction of surfactant is 0.5~3.0 wt%.

[0038] Optionally, the coating thickness of the nano-modifier in the middle of the tube is 5-50 μm.

[0039] Optionally, the gradient cooling includes a pre-cooling section and a crystallization section. The pre-cooling section adopts a combination of air cooling with a transverse wind speed of 8-12 m / s and liquid nitrogen spraying with a longitudinal flow rate of 40-60 mL / min. The crystallization section adopts air cooling with a transverse wind speed of 18-30 m / s and liquid nitrogen spraying with a longitudinal flow rate of 80-100 mL / min.

[0040] On the other hand, the present application also provides a thermoplastic resin-based carbon fiber composite tube, which is prepared by the method described in the first aspect.

[0041] Compared with the prior art, this application has at least the following beneficial effects:

[0042] 1. The present invention effectively enhances the fiber-matrix interface bonding force, improves the interface shear strength, reduces the delamination defect rate, and controls the porosity to <1.5% by adding a uniform coating (thickness 5-50 μm, mass fraction 0.3%-2.0%) between the wound prepreg layers.

[0043] 2. The present invention achieves precise temperature control during the hot bending process of the pipe by dynamically regulating the output power, which is beneficial to the efficient and uniform heating of the composite pipe matrix, improves the energy utilization rate by 20% to 45%, and achieves a temperature control accuracy of ±3°C, thus solving the problem of thermal degradation of the matrix caused by uneven heating of non-conductive materials.

[0044] 3. The present invention obtains the traction angle setting value of the three-dimensional hot bending device based on the target bending angle and the material properties of the pipe, which can compensate for the rebound and achieve precise control of the bending angle, ultimately forming an error of less than 3% and a rebound amount of less than 3°.

[0045] 4. The present invention performs gradient cooling on the pipe after hot bending, and the crystallinity of the thermoplastic matrix is ​​controlled with an accuracy of ±3%, which significantly reduces residual stress and micro defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the structure of the three-dimensional thermal bending device;

[0047] Figure 2 It is a structural diagram of the heating box;

[0048] Figure numerals: 1. guide wheel; 2. cooling box; 3. heating box; 4. controller; 5. clamping; 6. infrared radiation source; 7. reflector. DETAILED DESCRIPTION

[0049] The present invention is described in further detail below with reference to the accompanying drawings:

[0050] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are conventional methods.

[0051] The reagents and materials used in this example can be purchased conventionally. The quantitative experiments involved in the examples were repeated at least three times, and the results were averaged.

[0052] raw material:

[0053] Carbon fiber / nylon 6 narrow tape prepreg: CF / PA prepreg;

[0054] Carbon fiber / PEEK narrow tape prepreg: CF / PEEK prepreg.

[0055] Example 1

[0056] The three-dimensional thermal bending device used in this embodiment (such as Figure 1 ) is a prior art, including a driving member (not shown in the figure), a clamp 5, a heating box 3, a cooling box 2, a guide wheel 1, a six-degree-of-freedom robot arm (not shown in the figure) and a controller 4;

[0057] Driven by the driving member, the pipe slides along the clamping cavity of the clamp 5, and the clamp 5 is used to limit the vertical direction of the pipe;

[0058] The end of the pipe that passes through the clamp 5 passes through the heating box 3 and the cooling box 2 in sequence. The end of the pipe that passes through the cooling box 2 is connected to the guide wheel 1, which pulls the pipe to achieve thermal bending deformation. In this embodiment, the length of the heating box 3 (along the direction of pipe movement) is 20 cm, the length of the cooling box 2 (along the direction of pipe movement) is 10 cm, and the pipe movement rate is 300 mm / min.

[0059] The guide wheel 1 is mounted on a six-degree-of-freedom robotic arm, which is connected to the control end of the controller 4. The controller 4 is used to control the movement of the six-degree-of-freedom robotic arm according to the input traction angle setting value, thereby driving the pulley 1 to move, thereby achieving the bending of the pipe;

[0060] An infrared heat radiation heating device is added to the heating box 3 of the existing heat bending device to heat the pipe;

[0061] Heating box 3 (such as Figure 2 The structure of the heating box 3 is specifically as follows: the inner cavity of the heating box 3 is a hexagonal prism, and the top and bottom surfaces of its six sides are infrared radiation sources 6; the other four sides are reflective plates 7, and the angle between the reflective plates 7 and the vertical direction is ±20° to ensure that the energy is directed and focused on the curved area.

[0062] A three-dimensional hot bending forming method for a thermoplastic resin-based carbon fiber composite tube comprises:

[0063] (1) Preparation: Pipe with a length of 1500 mm, an outer diameter of 8 mm, and a wall thickness of 1.2 mm:

[0064] Using anhydrous ethanol as a solvent, silicon carbide and coupling agent KH560 were added to the solvent and stirred at 75°C for 2 hours to prepare a nano-modifier with a mass fraction of 1.5% of silicon carbide SiC (50 nanometers) and a mass fraction of 2.5% of coupling agent KH560.

[0065] A carbon fiber / nylon 6 narrow tape prepreg with a width of 9 mm and a thickness of 0.03 mm was wrapped around the outside of a metal tube with an outer diameter of 8 mm for 4 turns. After each turn, a layer of nano-modifier was sprayed and dried until the thickness of the nano-modifier coating between the wound tube layers was 15 μm, thereby obtaining a tube.

[0066] (2) Obtain the melting temperature (melting temperature peak is 220-230℃) and crystallization temperature (180-200℃) information of the pipe; the melting temperature and crystallization temperature are obtained by DSC test.

[0067] (3) Obtain the set value of the traction angle of the three-dimensional hot bending device based on the target bending angle and the material properties of the pipe;

[0068] Specifically, according to the target bending angle and the material properties of the pipe, the traction angle setting value of the three-dimensional hot bending device is determined, including:

[0069] Initialize the values ​​of α and β, where α and β are the first and second weight coefficients, respectively. Then, execute the following loop until the absolute value of the difference between the actual bending angle and the target bending angle is less than 3°. Output the set value of the traction angle for the last iteration:

[0070] Obtain the interfacial shear strength and resin melt viscosity of the pipe;

[0071] The pulling angle setting value is calculated based on α, β, the interface shear strength of the pipe and the viscosity of the resin melt;

[0072] Conduct hot bending test on pipes according to the set value of traction angle to obtain the actual bending angle;

[0073] calculating an absolute value of a difference between the actual bending angle and the target bending angle;

[0074] if the absolute value of the difference between the actual bending angle and the target bending angle is greater than or equal to 3°, dynamically adjusting the values of α and β.

[0075] calculating the pulling angle setting value according to α, β, the interfacial shear strength of the pipe material, and the resin melt viscosity, comprising:

[0076] ,

[0077] ,

[0078] ;

[0079] wherein, is the interfacial shear strength of the pipe material; is a set ideal interfacial strength (48 MPa); is the resin melt viscosity of the pipe material; is a set theoretical resin viscosity (3600 mPa·s); wherein satisfies: ), , .

[0080] In this embodiment, the initial α = 0.8, β = 0.2, k = 1.3, k' = 2.2, and after formula optimization, k = 1.42, k' = 2.86, the simulation error is 2.1%; springback compensation: the target bending angle is 90°, and the pulling angle setting value is θ = 90° × (1 + 2.89) = 347.7°.

[0081] (4) According to the pipe material, the infrared radiation wavelength setting value of the three-dimensional hot bending device is obtained; the array wavelength of the infrared radiation source 6 is 2.5~10μm, and in this embodiment, according to matching the nylon 6 amide bond absorption peak, the infrared radiation source 6 with a wavelength of 5.8μm is used.

[0082] (5) According to the melting temperature and wall thickness of the pipe material, the power density setting value of the three-dimensional hot bending device is obtained; the radiation power density of the equipment is 2~10W / cm². In this embodiment, the power density is , and 2 is taken according to the safety consideration of the radiation power density range of the equipment.

[0083] (6) The pipe is placed in a three-dimensional hot bending device, and the three-dimensional hot bending device is matched to the pulling angle setting value, the infrared radiation wavelength setting value and the power density setting value. The pipe is pulled at the melting temperature for hot bending (the six-degree-of-freedom robot arm has a repeatability accuracy of ±0.05mm to pull the front end of the pipe, and the preset path is a spatial spiral curve with a curvature radius of 60mm and a rise angle of 25°). Then, the hot-bent pipe is gradient-cooled to obtain the thermoplastic resin-based carbon fiber composite pipe.

[0084] Specifically, the step of drawing the pipe at the melting temperature for hot bending includes:

[0085] Initialize the output power of the three-dimensional heat bending device. The three-dimensional heat bending device heats the pipe with the output power and then performs the following cycle until the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is less than 0.5°C. Then, the pipe is pulled for heat bending:

[0086] Obtain the surface temperature of the pipe and calculate the absolute value of the difference between the surface temperature of the pipe and the melting temperature of the pipe;

[0087] If the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is greater than or equal to 0.5°C, obtain the pipe's thermal diffusivity, specific heat capacity, thermal conductivity, and the change in temperature deviation per unit time;

[0088] The power adjustment amount and the adjusted output power are obtained according to the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe.

[0089] The power adjustment amount and the adjusted output power are obtained based on the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe. The calculation formulas for the power adjustment amount ∆P and the adjusted output power P are as follows:

[0090] ,

[0091] P=P0+∆P;

[0092] Among them, the proportional coefficient , is the thermal diffusivity of the pipe (6.25 mm² / s); the integral coefficient , is the specific heat capacity (10J / KG·K); differential coefficient , γ is the thermal conductivity (=15W / m·K), P0 is the output power of the three-dimensional thermal bending device when measuring the temperature of the pipe, e is the difference between the surface temperature of the pipe and the melting temperature of the pipe during temperature measurement, Δe is the change in temperature deviation per unit time, Δe= , e0 is the difference between the pipe surface temperature and the melting temperature of the pipe during the last temperature measurement, and Δt is the time interval between the two temperature measurements.

[0093] For example, in this embodiment, the target temperature of the pipe is 225°C, the last measured temperature is 222°C, the current measured temperature is 220°C, and the sampling interval is 0.5s (e=+5°C, ), , so after 2 seconds , that is, the power of the infrared thermal radiation heating device is increased Control effect: The temperature rose from 220°C to 224.5°C (error 0.5°C).

[0094] In this example, gradient cooling consisted of a precooling section and a crystallization section. The precooling section was 100 mm long, the crystallization section was 100 mm long, and the pipe travel speed was 100 mm. The precooling section used a combination of air cooling at a transverse wind speed of 10 m / s and liquid nitrogen spray at a longitudinal flow rate of 40 mL / min. The crystallization section used air cooling at a transverse wind speed of 25 m / s and liquid nitrogen spray at a longitudinal flow rate of 80 mL / min. The final crystallinity control achieved was 48.3%, within the target of 50% ± 3%.

[0095] Example 2

[0096] This embodiment differs from the embodiment in that:

[0097] Prepare a tube (carbon fiber / PEEK composite tube) with a length of 1800 mm, an outer diameter of 6 mm, and a wall thickness of 2.4 mm;

[0098] Using acetone as solvent, SiO2 (30 nanometers) and PVP were added to the solvent and stirred at 75°C for 2 hours to prepare a nano-modifier with a SiO2 mass fraction of 0.8% and a PVP mass fraction of 0.5%.

[0099] The carbon fiber / PEEK narrow tape prepreg with a width of 9mm and a thickness of 0.04mm was wound on the outside of a metal tube with an outer diameter of 6mm, and wound for 6 layers. In order to suppress fiber slippage and interface delamination, a nano-modified layer was introduced: the nano-modified layer was applied between the prepreg layers by dip roller coating, so that the coating thickness between each layer of the wound tube was 10 ;

[0100] The DSC test shows that the melting peak of the PEEK matrix is ​​340-380°C, and the crystallization temperature range is 220-340°C, which can be used to obtain the optimal hot bending heating temperature and the crystallization temperature that matches the subsequent cooling temperature with the crystallinity.

[0101] Determination of the traction angle setting value: The initial correction factor (universal safety factor) is set to k=1.3 ( ), k'=2.2, after optimization, k=1.25, k'=1.95; Springback compensation: target bending angle 90°, actual traction angle , the springback after compensation is less than 3°. Therefore, this can avoid a large springback angle after hot bending.

[0102] According to the matching of PEEK carbonyl absorption peak, the wavelength was 7.9 Infrared radiation source 6.

[0103] The power density is .

[0104] The pipe is placed in a three-dimensional hot bending device, and the three-dimensional hot bending device is matched to the pulling angle setting value, the infrared radiation wavelength setting value and the power density setting value. The pipe is pulled at the melting temperature for hot bending (the six-degree-of-freedom robotic arm has a repeatability accuracy of ±0.05mm and pulls the pipe through the guide wheel 1. The preset path is a three-dimensional S-shaped curve with a curvature radius of 120mm and a rise angle of 30°). Then, the hot-bent pipe is gradient cooled to obtain the thermoplastic resin-based carbon fiber composite pipe.

[0105] Specifically, the step of drawing the pipe at the melting temperature for hot bending includes:

[0106] Initialize the output power of the three-dimensional heat bending device. The three-dimensional heat bending device heats the pipe with the output power and then performs the following cycle until the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is less than 0.5°C. Then, the pipe is pulled for heat bending:

[0107] Obtain the surface temperature of the pipe and calculate the absolute value of the difference between the surface temperature of the pipe and the melting temperature of the pipe;

[0108] If the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is greater than or equal to 0.5°C, obtain the pipe's thermal diffusivity, specific heat capacity, thermal conductivity, and the change in temperature deviation per unit time;

[0109] The power adjustment amount and the adjusted output power are obtained according to the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe.

[0110] The power adjustment amount and the adjusted output power are obtained based on the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe. The calculation formulas for the power adjustment amount ∆P and the adjusted output power P are as follows:

[0111] ,

[0112] P=P0+∆P;

[0113] Among them, the proportional coefficient , is the thermal diffusivity of the pipe (mm² / s); the integral coefficient , Cp is the specific heat capacity (J / KG·K); the differential coefficient , γ is the thermal conductivity (W / m·K), P0 is the output power of the three-dimensional thermal bending device when measuring the temperature of the pipe material, e is the difference between the surface temperature of the pipe material and the melting temperature of the pipe material when measuring the temperature, Δe is the change amount of the temperature deviation per unit time, Δe= , e0 is the difference between the surface temperature of the pipe material and the melting temperature of the pipe material when measuring the temperature last time, Δt is the time interval between two times of measuring the temperature.

[0114] Example: the target temperature of the carbon fiber / PEEK composite pipe is 380℃, the last sampling measured temperature is 373℃, the current sampling measured temperature is 370℃, and the sampling interval is 0.5s once (e=+10℃, is the last sampling temperature deviation , e is the current sampling temperature deviation , ), , so after 2 seconds , that is, the power of the infrared thermal radiation heating device is adjusted to . Control effect: the temperature rises from 380℃ to 378.8℃ (error 1.2℃)

[0115] The gradient cooling in this embodiment includes: a gradient air-cooling pre-cooling section (close to one side of the heating area, occupying half of the length of the cooling box 2) to prevent residual stress caused by sudden cooling, which adopts transverse air speed of 12m / s air cooling + longitudinal flow of 60mL / min liquid nitrogen spray cooling combination, and a crystallization section (away from one end of the heating area) which needs to quickly determine the inhibition of rebound, which adopts transverse air speed of 20m / s air cooling + longitudinal flow of 100mL / min liquid nitrogen spray combination. Finally, the crystallinity control is 32.5%, and the target is 33%±3%.

Claims

1. A three-dimensional hot bending forming method for a thermoplastic resin-based carbon fiber composite tube, characterized in that: include: Thermoplastic resin-based prepreg is wound into several layers and a nano-modifier is applied between the layers and dried to obtain a pipe; Obtain the melting temperature and crystallization temperature information of the pipe; According to the target bending angle and the material properties of the pipe, the pulling angle setting value of the three-dimensional hot bending device is obtained; According to the pipe material, the infrared radiation wavelength setting value of the three-dimensional thermal bending device is obtained; According to the melting temperature and wall thickness of the pipe, the power density setting value of the three-dimensional hot bending device is obtained; The tube is placed in a three-dimensional hot bending device, and the three-dimensional hot bending device is matched to the pulling angle setting value, the infrared radiation wavelength setting value and the power density setting value. The tube is pulled at the melting temperature for hot bending, and then the hot-bent tube is gradient cooled to obtain the thermoplastic resin-based carbon fiber composite tube.

2. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The method of determining the traction angle setting value of the three-dimensional heat bending device according to the target bending angle and the material properties of the pipe includes: Initialize the values ​​of α and β, where α and β are the first and second weight coefficients, respectively. Then, execute the following loop until the absolute value of the difference between the actual bending angle and the target bending angle is less than 3°. Output the set value of the traction angle for the last iteration: Obtain the interfacial shear strength and resin melt viscosity of the pipe; The pulling angle setting value is calculated based on α, β, the interface shear strength of the pipe and the viscosity of the resin melt; Conduct hot bending test on pipes according to the set value of traction angle to obtain the actual bending angle; Calculating the absolute value of the difference between the actual bending angle and the target bending angle; If the absolute value of the difference between the actual bending angle and the target bending angle is greater than or equal to 3°, the values ​​of α and β are dynamically adjusted.

3. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The calculation of the pull angle setting value according to α, β, the interface shear strength of the pipe and the resin melt viscosity includes: ， ， ； in, is the interfacial shear strength of the pipe; is the ideal interface strength set; is the resin melt viscosity of the pipe; The theoretical resin viscosity is set; satisfy:( ), , .

4. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The method of drawing the pipe at the melting temperature for hot bending comprises: Initialize the output power of the three-dimensional heat bending device. The three-dimensional heat bending device heats the pipe with the output power and then performs the following cycle until the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is less than 0.5°C. Then, the pipe is pulled for heat bending: Obtain the surface temperature of the pipe and calculate the absolute value of the difference between the surface temperature of the pipe and the melting temperature of the pipe; If the absolute value of the difference between the pipe surface temperature and the pipe melting temperature is greater than or equal to 0.5°C, obtain the pipe's thermal diffusivity, specific heat capacity, thermal conductivity, and the change in temperature deviation per unit time; The power adjustment amount and the adjusted output power are obtained according to the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe.

5. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The power adjustment amount and the adjusted output power are obtained based on the thermal diffusivity, specific heat capacity, thermal conductivity and the change in temperature deviation per unit time of the pipe. The calculation formulas for the power adjustment amount ∆P and the adjusted output power P are as follows: ， P=P0+∆P; Among them, the proportional coefficient , is the thermal diffusivity of the pipe (mm² / s); the integral coefficient , is the specific heat capacity (J / KG·K); differential coefficient , γ is the thermal conductivity (W / m·K), P0 is the output power of the three-dimensional thermal bending device when measuring the temperature of the pipe, e is the difference between the surface temperature of the pipe and the melting temperature of the pipe during temperature measurement, Δe is the change in temperature deviation per unit time, Δe= , e0 is the difference between the pipe surface temperature and the melting temperature of the pipe during the last temperature measurement, and Δt is the time interval between the two temperature measurements.

6. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The method of determining the power density setting value of the three-dimensional heat bending device according to the melting temperature and wall thickness of the pipe comprises: Obtain the pipe wall thickness and melting temperature, and calculate the power density setting value using the following formula: Power density = .

7. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The preparation of the nanomodifier comprises the following method: dispersing nanoparticles in a solvent and adding a surfactant to obtain the nanomodifier; the nanoparticles are one or more of silicon carbide, silicon dioxide or carbon nanotubes; preferably, the mass fraction of the nanoparticles in the nanomodifier is 0.3-2.0 wt %, and the mass fraction of the surfactant is 0.5-3.0 wt %.

8. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The coating thickness of the nano-modifier in the middle of the pipe is 5-50 μm.

9. The three-dimensional hot bending forming method of thermoplastic resin-based carbon fiber composite tube according to claim 1, characterized in that: The gradient cooling includes a pre-cooling section and a crystallization section. The pre-cooling section adopts a combination of air cooling with a transverse wind speed of 8-12 m / s and liquid nitrogen spraying with a longitudinal flow rate of 40-60 mL / min. The crystallization section adopts a combination of air cooling with a transverse wind speed of 18-30 m / s and liquid nitrogen spraying with a longitudinal flow rate of 80-100 mL / min.

10. A thermoplastic resin-based carbon fiber composite tube, characterized in that: It is prepared by the method according to any one of claims 1 to 9.

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