Continuous fiber Joule self-heating type thermoplastic composite material additive manufacturing end device facing vacuum environment

Abstract

A continuous fiber Joule self-heating type thermoplastic composite material additive manufacturing end device facing a vacuum environment belongs to the field of composite material additive manufacturing and comprises an insulating wire feeding clamping mechanism module, a nozzle infrared temperature measuring module and an adjustable Joule heating module. A closed-loop conductive structure is constructed in a wire feeding path, a positive electric brush is in contact with a conductive bearing to serve as a power supply input end, a circular terminal arranged at a nozzle serves as a power supply negative electrode, a positive and negative electrode loop is formed in the process that a prepreg wire is fed to the nozzle, and the wire is heated in a Joule self-heating mode. And the problems of high energy consumption, low heat transfer efficiency and the like are avoided. The wire feeding mechanism adopts a vacuum stepping motor and an insulation transmission structure to drive a conductive bearing to realize ordered conveying of preimpregnated wires, the distance between a nozzle and a cathode is adjusted to adapt to materials with different melting points, and closed-loop control of heating temperature is realized in combination with follow-up infrared temperature measurement. The device is suitable for printing operation in the vacuum environment, and the heating rate of the fiber composite material printing tail end is increased.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing of composite materials and relates to an end device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment. Background Technology

[0002] In specialized fields such as aerospace, deep space exploration, and vacuum precision manufacturing, the demand for lightweight, high-strength, and integrated molding of structural components is increasingly urgent. Continuous fiber reinforced thermoplastic composites, with their strong designability, excellent mechanical properties, and integrated manufacturing potential through reversible phase transitions, have become an ideal material for structural components in vacuum environments. Furthermore, 3D printing technology, which does not involve chemical curing reactions, offers advantages such as low outgassing risk and insensitivity to environmental pressure and humidity, making it the preferred process for high-quality manufacturing of thermoplastic composite components in vacuum environments. However, the suppressed convective heat transfer characteristics of a vacuum environment (significantly limited thermal convection and lack of an effective air heat transfer medium) place stringent requirements on the heating technology for thermoplastic composite 3D printing, demanding low heating energy consumption, fast reaction speed, and high heat transfer efficiency. Currently, the end of thermoplastic composite 3D printing generally uses heating rods or resistance sheets to heat the nozzle heating block, which then sequentially transfers heat to the nozzle. Finally, the prepreg filament is softened by heat through local contact conduction between the nozzle and the prepreg filament, as well as through air convection between the nozzle and the prepreg filament. Existing end-effector heating methods can meet the heating requirements of ground environments, but they face problems such as high heat loss and low heating efficiency in vacuum environments. In a vacuum, the air medium disappears, and the heat convection path completely fails, relying only on limited contact conduction and radiation heat transfer. This leads to a sharp increase in heat loss, and the heat from the heating block is difficult to efficiently transfer to the prepreg filament. Simultaneously, the lag in multi-medium transfer further slows down the heating response speed, making it difficult to meet the process requirements of rapid prototyping in a vacuum environment. Moreover, to compensate for the response lag, it is often necessary to increase the heating power or extend the heating time, resulting in increased ineffective heat loss and energy consumption, severely restricting the application of continuous fiber thermoplastic composite 3D printing technology in special vacuum scenarios. Therefore, for the special working conditions of limited heat convection in a vacuum environment, there is an urgent need to develop a printing end with low heating energy consumption, fast response speed, and high heat transfer efficiency to solve the adaptability defects of existing indirect heating end-effectors in vacuum environments and meet the energy-saving and efficient 3D printing requirements of thermoplastic composites in vacuum scenarios.

[0003] To address this, Chinese invention patent CN119748858A employs a design where a heating coil is fitted around the outside of the heating block. Heat is transferred to the nozzle via electrical heating, causing the composite material to melt and extrude. However, a gap exists between the heating coil and the heating block in this patent, preventing heat transfer through conduction and significantly hindering efficient heat transfer, especially in a vacuum environment where there is no convective heat transfer, resulting in a slower heat transfer rate and a longer time for the nozzle to reach the set temperature, leading to a slower response. Chinese invention patent CN105499572A utilizes an electromagnetic induction coil to generate an electromagnetic field, causing eddy currents within the metal heating block to convert electrical energy into heat energy. This method can effectively improve the efficiency of fused deposition modeling 3D printing; however, the overall complexity and cost of the equipment are high, and its overall energy consumption is not significantly superior to traditional heating methods. Chinese invention patent CN111186138A uses an infrared radiation device to heat the upper and lower surfaces of a continuous fiber bundle, which can achieve uniform dispersion and full impregnation of the continuous fiber in the resin matrix, resulting in a material with good interfacial bonding. However, due to the limited infrared radiation heat transfer efficiency and the low absorption rate of thermoplastic resin to radiation energy, the utilization rate of infrared heating energy is limited, and ineffective energy consumption is easy to occur. At the same time, uneven heating leads to a large temperature gradient inside the material, which affects the molding stability.

[0004] Therefore, in order to solve the problem that existing printing end heating devices cannot achieve low energy consumption and fast response, it is necessary to develop an energy-efficient 3D printing end device that uses heat conduction as the primary heating method. Summary of the Invention

[0005] To address the problems of existing technologies, this invention provides a continuous fiber Joule self-heating thermoplastic composite additive manufacturing end device for vacuum environments. Because heat conduction is slow in a vacuum environment, traditional external heat sources such as heating rods cannot effectively heat the prepreg filament to achieve the required resin matrix softening for printing. Therefore, this invention replaces the traditional heating rod method with a self-heating heating method using electrodes connected to both ends of the prepreg filament for internal resistance heating. The main components include a closed-loop conductive structure in the filament feeding path, with a positive brush and conductive bearing serving as the power input, and a circular terminal holding the continuous fiber at the nozzle serving as the negative power input. This creates a positive and negative circuit in the prepreg filament as it is fed to the nozzle, allowing direct heating of the filament using Joule self-heating, achieving low energy consumption, high thermal response, and high heat transfer efficiency in a vacuum environment. In addition, this invention uses a vacuum stepper motor as the wire feeding power source. The motor shaft and the insulated drive shaft are connected by a coupling, which ensures stable rotation of the drive wheel while providing insulation protection against leakage risks during the energization process. Conductive bearings are used to flexibly clamp the pre-impregnated wire to achieve orderly conveying. For thermoplastic resin materials with different melting points, the electrode spacing is changed by adjusting the relative height between the nozzle and the negative terminal of the power supply, thus achieving adjustable heating parameters. Furthermore, an infrared camera is used to measure the temperature of the molten wire extruded at the nozzle in real time, and a synchronous belt mechanism keeps it always behind the nozzle in the direction of movement, thereby achieving closed-loop feedback and control of the heating temperature.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A continuous fiber Joule self-heating thermoplastic composite additive manufacturing end-point device for vacuum environments includes an insulated wire feeding and clamping mechanism module 1, a nozzle infrared temperature measurement module 2, and an adjustable Joule heating module 3. The insulated wire feeding and clamping mechanism module 1 mainly consists of a stepper motor, coupling, insulated drive shaft, conductive bearing, and spring, used for feeding pre-impregnated wire and clamping it according to the wire diameter. The nozzle infrared temperature measurement module 2 mainly consists of a nozzle and an infrared camera, used for temperature detection and closed-loop control. The adjustable Joule heating module 3 mainly consists of a guide rail, slider, brush, and power circular terminal, used for power path design and adjustable measures for different energizing lengths for thermoplastic resins with different melting points. Specifically: The insulating wire feeding clamping mechanism module 1 includes a vacuum stepper motor 1-1, a motor base 1-2, a coupling 1-3, an insulating drive shaft 1-4, a drive wheel 1-5, a base bracket 1-6, a guide mechanism 1-7, a guide tube 1-8, a bearing slide 1-9, a bearing support 1-10, a conductive bearing 1-11, and a preload spring 1-12. The motor base 1-2 is fixed to the vacuum stepper motor 1-1; the insulating drive shaft 1-4 is connected to the motor shaft of the vacuum stepper motor 1-1 via the coupling 1-3; the drive wheel 1-5 is fixed to the insulating drive shaft 1-4 and secured with a set screw; the base bracket 1-6 is fixed to the upper end of the motor base 1-2; the guide mechanism 1-7 is fixed to the base bracket 1-6, and the guide tube 1-8 is nested into the guide mechanism 1-7 to ensure coaxiality; the bearing slide 1-9 is fixed to the motor base 1-2 with bolts, and... The bearing support 1-10 is fixed above the slot provided in the motor base 1-2; the bearing support 1-10 is fixed in the slide rail provided in the bearing slide 1-9 and can move left and right in the slide rail; the conductive bearing 1-11 is fixed on the positioning cylinder designed in the bearing support 1-10; the preload spring 1-12 is nested between the cylinder designed in the bearing slide 1-9 and the cylinder at the end of the bearing support 1-10; the pressure generated by the compression of the preload spring 1-12 enables the middle drive wheel 1-5 and the conductive bearing 1-11 to flexibly clamp the prepreg wire, ensuring orderly downward conveying.

[0007] Furthermore, the slot on the motor base 1-2 is located at the lower end of the threaded hole of the fixed bearing slide 1-9, and extends into a step for limiting the bearing slide 1-9 in the Z direction.

[0008] Furthermore, the bearing slide 1-9 is a U-shaped component, with slide rails constructed on the inner walls on both sides of the bearing slide 1-9.

[0009] Furthermore, the cylinder on the bearing slide 1-9 is located on the inner wall of the end.

[0010] Furthermore, the bearing support 1-10 is also a U-shaped component, smaller in size than the bearing slide 1-9. Cylindrical structures are constructed on the outer walls of both sides of the bearing support 1-10, allowing it to slide left and right on the slide rails of the bearing slide 1-9.

[0011] Furthermore, the positioning cylinder on the bearing support 1-10 is located on the outer wall of the end, satisfying the requirement of being coaxial with the cylinder provided in the bearing slide 1-9.

[0012] Furthermore, the positioning cylinders on the bearing supports 1-10 are located on the inner walls on both sides, satisfying the interference fit of the inner diameter of the conductive bearings 1-11 on the positioning cylinders.

[0013] The nozzle infrared temperature measurement module 2 includes a nozzle 2-1, a flange sleeve 2-2, a large synchronous pulley 2-3, a guide tube 2-4, a bearing 2-5, an infrared camera fixing component 2-6, an infrared camera 2-7, a synchronous belt 2-8, a small synchronous pulley 2-9, and a small motor 2-10. The nozzle 2-1 is threaded to the flange sleeve 2-2; the flange sleeve 2-2 is positioned with the base extension 3-1 and fixed with bolts to ensure the stability of the printing end; the guide tube 2-4 is nested into the bushing of the flange sleeve 2-2 and contacts the upper end of the nozzle 2-1 for positioning; the bearing 2-5 is sleeved on the guide tube 2-4, and through an interference fit between its inner diameter and the guide tube 2-4, and by the flange sleeve 2-2 pressing against the inner ring of the bearing 2-5 from below, axial positioning of the bearing 2-5 is achieved; the large synchronous pulley 2-3 is fitted with the outer diameter of the bearing 2-5 to achieve axial rotation of the large synchronous pulley 2-3. The infrared camera 2-7 provides a basis for detecting temperature around the end of the nozzle 2-1. The infrared camera fixing piece 2-6 is attached to the bottom of the large synchronous pulley 2-3. The infrared camera 2-7 is connected to the positioning post of the infrared camera fixing piece 2-6, and its lens is aligned with the nozzle 2-1. The small motor 2-10 is connected to the side through the threaded hole of the motor base 1-2, and a small synchronous pulley 2-9 is mounted on the motor shaft of the small motor 2-10. The synchronous belt 2-8 is fitted between the large synchronous pulley 2-3 and the small synchronous pulley 2-9 to ensure that the infrared camera 2-7 can rotate around the nozzle 2-1 following the path change during printing, thereby realizing temperature detection.

[0014] The adjustable Joule heating module 3 includes a base extension 3-1, a slider 3-2, a slider limiter 3-3, an adjusting nut 3-4, a slide rail 3-5, a positive power plug 3-6, a power interface 3-7, a brush 3-8, a negative power circular terminal 3-9, and a hexagonal nut 3-10. The power interface 3-7 is fixed to the side of the motor base 1-2, and the positive power plug 3-6 is connected to the power interface 3-7 to input current. The brush 3-8 is fixed to the motor base 1-2, with one end contacting the power interface 3-7 and the other end contacting the conductive bearing 1-11, thus flexibly clamping the pre-impregnated wire and inputting current. The slide rail 3-5 is bolted to the motor base 1-2, and the slider 3-2, through its interaction with the slide rail 3-5, can move up and down, thereby moving the negative power circular terminal 3-9 to adjust the distance between the positive and negative circuits. The base extension 3-1 is fixed to the slider 3-2. -2, clamping of the printing end is achieved through cooperation with flange sleeve 2-2; the negative power circular terminal 3-9 is fitted under the nozzle 2-1, and the negative power circular terminal 3-9 is fastened by the thread provided at the lower end of the nozzle 2-1 and the hexagonal nut 3-10, realizing the power supply path; the slider limit 3-3 is located at the lower end of the motor base 1-2; the adjusting nut 3-4 is connected to the lower end of the motor base 1-2, and the up and down movement of the slider limit 3-3 is controlled by rotating the thread of the adjusting nut 3-4, thereby adjusting the distance between the conductive bearing 1-11 and the negative power circular terminal 3-9, realizing adjustable Joule heating.

[0015] Furthermore, the conductive bearing 1-11 in the insulating wire feeding clamping mechanism module 1 is connected to the positive power supply through contact with the brush 3-8, the nozzle 2-1 is connected to the circular terminal 3-9 of the negative power supply, and the carbon fiber in the pre-impregnated wire passing between the two forms a power circuit, realizing the self-resistance internal heating of the carbon fiber, and ensuring that only the pre-impregnated wire at both ends of the electrode is energized and heated, avoiding the phenomenon of premature melting of the wire.

[0016] Furthermore, the distance between the conductive bearing 1-11 and the drive wheel 1-5 in the insulating wire feeding clamping mechanism module 1... The prepreg wire diameter is adaptively adjusted based on the diameter of the prepreg wire at different times. The distance between the two satisfy: The distance between the conductive bearing 1-11 and the drive wheel 1-5 Specifically, it refers to the gap between the outer walls of the two surfaces.

[0017] Furthermore, the conductive bearing 1-11, nozzle 2-1, and brush 3-8 in the adjustable Joule heating module 3 are all made of easily conductive materials, selected from brass, bronze, and silver copper, with a conductivity range of 50.0-60.0 MS / m.

[0018] Furthermore, the conduits 1-8 are made of polytetrafluoroethylene, which has a heat resistance greater than 260°C.

[0019] A method for using a continuous fiber Joule self-heating thermoplastic composite additive manufacturing end device for vacuum environments includes the following steps: First, the vacuum stepper motor 1-1 is bolted to the motor base 1-2; the coupling 1-3 is fixed to the motor shaft of the vacuum stepper motor 1-1 with a set screw, and the other end is also fixed to the insulated drive shaft 1-4 with a set screw; the drive wheel 1-5 is fixed to the insulated drive shaft 1-4 with a set screw; the base bracket 1-6 is bolted to the upper end of the motor base 1-2; the guide mechanism 1-7 is fixed by engaging with the threaded hole designed on the base bracket 1-6; the guide tube 1-8 is manually inserted into the guide mechanism 1-2. -7; the bearing slide 1-9 is placed on the slot of the motor base 1-2 and fixed with bolts after being aligned with the threaded hole; the bearing support 1-10 is manually clamped into the slide rail of the bearing slide 1-9 by the cylinders on both sides; the conductive bearing 1-11 is nested on the positioning cylinder of the bearing support 1-10; the two ends of the preload spring 1-12 are respectively sleeved on the cylinders of the bearing slide 1-9 and the bearing support 1-10, so that there is a small squeezing force between the drive wheel 1-5 and the conductive bearing 1-11, which meets the requirements of flexible clamping of the prepreg wire.

[0020] In the second step, nozzle 2-1 is threaded onto flange sleeve 2-2 via its outer wall thread; flange sleeve 2-2 is secured to base extension 3-1 with bolts; guide tube 2-4 is manually inserted into the bushing of flange sleeve 2-2 until it contacts the upper end face of nozzle 2-1; bearing 2-5 is manually inserted into guide tube 2-4 and extends downwards to the upper end face of flange sleeve 2-2; large synchronous pulley 2-3 is fitted onto the outer ring of bearing 2-5; infrared camera mounting component 2-6 is bolted to large synchronous pulley 2-3. Below; Infrared camera 2-7 is connected to the positioning post of infrared camera fixing piece 2-6 to ensure that the lens is aligned with the end of nozzle 2-1; Small motor 2-10 is engaged and fastened to the threaded hole on the right side of motor base 1-2; Small synchronous pulley 2-9 is fixed to the motor shaft of small motor 2-10 by set screw; Synchronous belt 2-8 is fitted between large synchronous pulley 2-3 and small synchronous pulley 2-9 to ensure that the rotation of small motor 2-10 can drive infrared camera 2-7 to rotate around the end of nozzle 2-1, thereby realizing temperature detection.

[0021] Thirdly, the power interface 3-7 is fixed to the right side of the motor base 1-2, and the positive power supply 3-6 is connected to the power interface 3-7 to input current; the brush 3-8 is fixed in the positioning hole of the motor base 1-2, with one end of the brush 3-8 contacting the power interface 3-7 and the other end contacting the conductive bearing 1-11; the slide rail 3-5 is fixed to the lower end of the motor base 1-2 by bolts, and the slider 3-2 can move up and down on the track by cooperating with the slide rail 3-5; the base extension 3-1 connects to the threaded hole on the slider 3-2. The components are fitted and fixed together to complete the clamping of the entire printing end; the negative power circular terminal 3-9 is inserted under the nozzle 2-1, and the negative power circular terminal 3-9 is fastened by the engagement of the thread provided under the nozzle 2-1 and the hexagonal nut 3-10; the slider 3-3 is fixed to the lower end of the motor base 1-2 by the adjusting nut 3-4, and the slider limit 3-3 is moved up and down by rotating the thread of the adjusting nut 3-4, thereby adjusting the distance between the conductive bearing 1-11 and the negative power circular terminal 3-9, realizing adjustable Joule heating.

[0022] The beneficial effects of this invention are: (1) The continuous fiber Joule self-heating thermoplastic composite additive manufacturing end device designed in this invention connects the positive power supply through the contact of the conductive bearing 1-11 and the brush 3-8, the nozzle 2-1 and the negative power supply circular terminal 3-9 are connected, and the carbon fiber in the prepreg wire passing between the two forms a power circuit, which can realize the self-resistance internal heating of the two ends of the prepreg wire, significantly improve the heating rate of the fiber composite printing end, and solve the problems of slow heating temperature rise and high energy consumption. (2) The present invention switches the distance between the two electrodes by adjusting the height of the base extension 3-1 to meet the heating requirements of materials with different properties (such as PEEK, PA) with low heating energy consumption, fast response speed and high heat transfer efficiency. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the continuous fiber Joule self-heating thermoplastic composite additive manufacturing end structure designed in this invention, which is applicable to the additive manufacturing of fiber composite materials. Figure 2 This is a schematic diagram of the insulating wire feeding clamping module structure of the continuous fiber Joule self-heating thermoplastic composite additive manufacturing end structure designed for this invention, used for actively feeding continuous fiber thermoplastic resin prepreg wire. Figure 3 This is a schematic diagram of the nozzle infrared temperature measurement module structure of the end structure of the continuous fiber Joule self-heating thermoplastic composite additive manufacturing designed for this invention, used to detect the printing temperature of continuous fiber thermoplastic composites. Figure 4A schematic diagram of the nozzle infrared temperature measurement module structure of the nozzle of the continuous fiber Joule self-heating thermoplastic composite additive manufacturing end structure designed for this invention. Figure 4 (a) is a schematic diagram of the nozzle infrared temperature measurement module structure of the continuous fiber Joule self-heating thermoplastic composite additive manufacturing end structure designed in this invention, used for printing prepreg wire; Figure 4 (b) in the middle is Figure 4 (a) 2-2 sectional view; Figure 5 This is a schematic diagram of the adjustable Joule heating module structure at the end of the continuous fiber Joule self-heating thermoplastic composite additive manufacturing process designed for this invention. It is used to realize the power supply path and adjust the distance between the two ends of the electrode according to the thermoplastic resin wire with different melting points. Figure 6 A schematic diagram of the power circuit at the end of the continuous fiber Joule self-heating thermoplastic composite additive manufacturing process designed for this invention.

[0024] In the diagram: 1. Insulating wire feeding and clamping mechanism module; 2. Nozzle infrared temperature measurement module; 3. Adjustable Joule heating module; 1-1 Vacuum stepper motor, 1-2 Motor base, 1-3 Coupling, 1-4 Insulated drive shaft, 1-5 Drive wheel, 1-6 Base bracket, 1-7 Guide mechanism, 1-8 Conduit, 1-9 Bearing slide, 1-10 Bearing support, 1-11 Conductive bearing, 1-12 Preload spring; 2-1 Nozzle, 2-2 Flange sleeve, 2-3 Large synchronous pulley, 2-4 Guide tube, 2-5 Bearing, 2-6 Infrared camera mounting hardware, 2-7 Infrared camera, 2-8 Synchronous belt, 2-9 Small synchronous pulley, 2-10 Small motor; 3-1 Base extension, 3-2 Slider, 3-3 Slider limit, 3-4 Adjusting nut, 3-5 Slide rail, 3-6 Positive power plug, 3-7 Power interface, 3-8 Brush, 3-9 Negative power circular terminal, 3-10 Hexagonal nut. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0026] Example 1 Taking the printing of PA-CF composite material samples as an example, continuous fiber PA resin-based composite material with a wire diameter of 0.4 mm was selected for printing. Based on the material properties, appropriate process parameters were selected to carry out this example; the printing temperature was set to 270℃ and the printing speed was 4 mm / s.

[0027] A continuous fiber Joule self-heating thermoplastic composite additive manufacturing end for vacuum environments includes a filament feeding module, a flexible clamping module, and a nozzle temperature measurement module. The insulating wire feeding clamping mechanism 1 includes a vacuum stepper motor 1-1, a motor base 1-2, a coupling 1-3, an insulating drive shaft 1-4, a drive wheel 1-5, a base bracket 1-6, a guide mechanism 1-7, a guide tube 1-8, a bearing slide 1-9, a bearing support 1-10, a conductive bearing 1-11, and a preload spring 1-12. The vacuum stepper motor 1-1 is fixed to the motor base 1-2 with bolts. The insulating drive shaft 1-4 is connected to the motor shaft of the vacuum stepper motor 1-1 via the coupling 1-3. The drive wheel 1-5 is fixed to the insulating drive shaft 1-4 and secured with a set screw. The base bracket 1-6 is fixed to the upper end of the motor base 1-2. The guide mechanism 1-7 is fixed to the base bracket 1-6. The guide tube 1-8 is nested into the guide mechanism 1-7 to ensure that the two... The bearing slide 1-9 is fixed to the motor base 1-2 by bolts and placed above the slot provided on the motor base 1-2; the bearing support 1-10 is fixed in the slide rail provided in the bearing slide 1-9 and can move left and right in the slide; the conductive bearing 1-11 is fixed on the positioning cylinder designed on the bearing support 1-10; the preload spring 1-12 is nested between the cylinder designed on the bearing slide 1-9 and the cylinder at the end of the bearing support 1-10; the pressure generated by the compression of the preload spring 1-12 realizes the squeeze force between the middle drive wheel 1-5 and the conductive bearing 1-11, so that when the continuous fiber PA resin-based composite material passes through the guide tube 1-8 and downwards through the drive wheel 1-5 and the conductive bearing 1-11, it realizes flexible clamping and ensures orderly downward conveying.

[0028] The nozzle infrared temperature measuring device 2 includes a nozzle 2-1, a flange sleeve 2-2, a large synchronous pulley 2-3, a guide tube 2-4, a bearing 2-5, an infrared camera fixing component 2-6, an infrared camera 2-7, a synchronous belt 2-8, a small synchronous pulley 2-9, and a small motor 2-10. The nozzle 2-1 is threaded to the flange sleeve 2-2. The flange sleeve 2-2 is positioned with the base extension 3-1 and fixed with bolts to ensure the stability of the printing end. The guide tube 2-4 is nested into the bushing of the flange sleeve 2-2 and contacts the upper end of the nozzle 2-1 to complete the limiting. The bearing 2-5 is fixed by the interference fit between its inner diameter and the guide tube 2-4 and the contact with the flange sleeve 2-2. The large synchronous pulley 2-3 and the bearing... The outer diameter of 2-5 is fitted to enable the axial rotation of the large synchronous pulley 2-3; the infrared camera fixing piece 2-6 is attached below the large synchronous pulley 2-3; the infrared camera 2-7 is connected to the positioning post of the infrared camera fixing piece 2-6, and its lens is aligned with the nozzle 2-1; the small motor 2-10 is connected to the side through the threaded hole of the motor base 1-2, and a small synchronous pulley 2-9 is mounted on the motor shaft of the small motor 2-10; the synchronous belt 2-8 is fitted between the large synchronous pulley 2-3 and the small synchronous pulley 2-9 to ensure that after the continuous fiber PA resin-based composite material is extruded from the end of the nozzle 2-1 during the printing process, the infrared camera 2-7 can rotate according to the path changes to detect the temperature of the extruded wire at the end.

[0029] The adjustable Joule heating device 3 includes a base extension 3-1, a slider 3-2, a slider limiter 3-3, an adjusting nut 3-4, a slide rail 3-5, a positive power plug 3-6, a power interface 3-7, a brush 3-8, a negative power circular terminal 3-9, and a hexagonal nut 3-10. The power interface 3-7 is fixed to the side of the motor base 1-2. The positive power plug 3-6 is connected to the power interface 3-7 to input current. The brush 3-8 is fixed to the motor base 1-2, with one end contacting the power interface 3-7 and the other end contacting the conductive bearing 1-11, thus flexibly clamping the pre-impregnated wire and inputting current. The slide rail 3-5 is fixed to the motor base 1-2 with bolts. The slider 3-2, through its cooperation with the slide rail 3-5, can... The system moves up and down, thereby moving the negative power supply circular terminal 3-9 to adjust the distance between the positive and negative circuits. The base extension 3-1 is fixed on the slider 3-2 and clamps the printing end through its cooperation with the flange sleeve 2-2. The negative power supply circular terminal 3-9 is inserted under the nozzle 2-1 and secured by the thread on the lower end of the nozzle 2-1 and the hexagonal nut 3-10, thus establishing a power supply path. The adjusting nut 3-4 is connected to the lower end of the motor base 1-2 and controls the up and down movement of the slider limit 3-3 by rotating the thread, thereby adjusting the distance between the electrodes and appropriately adjusting the length of the continuous fiber PA resin-based composite material between them, achieving adjustable Joule heating.

[0030] The conductive bearing 1-11 in the adjustable Joule heating device 3, together with the nozzle 2-1 and the continuous fibers in the continuous fiber PA resin-based composite material between them, form a power circuit to achieve self-resistance internal heating of carbon fiber and ensure that only the composite material at both ends of the electrode is energized and heated, thus avoiding premature melting of the wire.

[0031] Before the experiment begins, a continuous fiber-reinforced PA-based resin filament is passed through the insulated wire feeding and holding mechanism module, and then exits from nozzle 2-1 in the nozzle infrared temperature measurement module, ensuring close contact between the continuous fiber-reinforced PA-based resin filament, conductive bearing 1-11, and nozzle 2-1. An adjustable power supply with an input current of 0.25A is used, while an infrared camera 2-7 at nozzle 2-1 measures the temperature. Printing begins when the preset temperature of 270℃ is reached. The molten filament is controlled by the printing equipment to melt and stack along a specific trajectory, ultimately obtaining a high-performance fiber composite material printed sample. During the printing process, when the infrared camera 2-7 detects that the filament temperature is higher or lower than the set temperature, the power supply output current is adjusted to bring the filament temperature close to the set value.

[0032] Example 2 This embodiment aims to illustrate the applicability of the device of the present invention to different types of conductive thermoplastic wires. The specific details are as follows: Three different filaments were selected: continuous carbon fiber PA-based filament, PEEK-based prepreg filament, and continuous glass fiber PA-based prepreg filament containing short fibers. The melting point of PA is 210℃, the melting point of PEEK resin is 343℃, and the printing temperature of the PA-based prepreg filament containing glass fiber, which does not have conductive properties, was set to 270℃; the printing temperature of the PEEK-based filament was set to 400℃, and the printing speed of all filaments was 4mm / s.

[0033] The other steps are the same as in Example 1. Since the resistance and melting point of the materials are not similar, to ensure sufficient melting of the matrix material, the height of the negative electrode at the nozzle end is adjusted by rotating adjusting nut 3-4 to change the distance between the two ends of the electrode and the magnitude of the initial current, so that the reaction time of the self-resistive internal heating is roughly the same when using different wires. This example successfully printed samples of PA-based, PEEK-based continuous fibers, and short carbon fiber continuous glass fiber PA-based prepreg wires. The results show that by adjusting the distance between the two ends of the electrode and the magnitude of the power supply output current, this device can effectively be applied to conductive thermoplastic wires with different resin matrices and fiber types.

[0034] This invention primarily designs a system using a vacuum stepper motor as the power source for wire feeding. A coupling connects the motor shaft to the insulated drive shaft, ensuring the rotation of the drive wheel while preventing leakage of current during operation. Conductive bearings flexibly clamp the pre-impregnated wire, achieving orderly wire feeding. The invention also incorporates a power input terminal via a brush that contacts the bearing, and a circular terminal clamped at the nozzle as the negative terminal, thus achieving a closed-loop connection between wire feeding, the fiber bundle at the nozzle, and the positive and negative terminals. To accommodate thermoplastic resins with different melting points, the height of the nozzle and the negative terminal are adjusted, thereby regulating the distance between the two ends of the electrodes. Furthermore, an infrared camera is used to measure the temperature of the freshly extruded molten wire at the nozzle, and a synchronous belt can drive the infrared camera to always be positioned at the rear end of the nozzle's movement direction, enabling closed-loop feedback and adjustment of the appropriate heating temperature.

[0035] The above embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. 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 modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A continuous fiber Joule self-heating thermoplastic composite additive manufacturing end device for vacuum environments, characterized in that, The continuous fiber Joule self-heating thermoplastic composite additive manufacturing end device includes an insulated wire feeding and clamping mechanism module (1), a nozzle infrared temperature measurement module (2), and an adjustable Joule heating module (3). The insulated wire feeding and clamping mechanism module (1) consists of a vacuum stepper motor, a coupling, an insulated drive shaft, a conductive bearing, and a spring, providing a wire feeding path for feeding prepreg wire and clamping the wire diameter according to its own needs. The nozzle infrared temperature measurement module (2) consists of a nozzle and an infrared camera, used for temperature detection and closed-loop control. The adjustable Joule heating module consists of a guide rail, a slider, a brush, and a power supply circular terminal, used for power supply path design and adjustable measures for different energizing lengths for thermoplastic resins with different melting points. In the wire feeding path, a closed-loop conductive structure is constructed. The positive power plug and the conductive bearing are used as the power input terminal. The negative power circular terminal for clamping the continuous fiber is set at the nozzle of the nozzle infrared temperature measurement module (2) as the negative power terminal. This allows the prepreg wire to form a positive and negative circuit during the wire feeding process to the nozzle. The prepreg wire is directly heated by the Joule self-heating method. The electrode spacing is changed by adjusting the relative height between the nozzle and the negative power terminal, so that the heating parameters can be adjusted. The insulating wire feeding clamping mechanism module (1) uses a vacuum stepper motor as the wire feeding power source. The motor shaft and the insulating drive shaft are connected by a coupling. While ensuring the stable rotation of the drive wheel, the leakage risk during the power supply process is insulated and protected. The conductive bearing is used to flexibly clamp the prepreg wire to achieve orderly conveying. The nozzle infrared temperature measurement module (2) uses an infrared camera to measure the temperature of the molten wire extruded at the nozzle in real time. The synchronous belt mechanism keeps it always behind the nozzle movement direction to achieve closed-loop feedback and control of the heating temperature.

2. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 1, characterized in that, The insulating wire feeding clamping mechanism module (1) includes a vacuum stepper motor (1-1), a motor base (1-2), a coupling (1-3), an insulating drive shaft (1-4), a drive wheel (1-5), a base bracket (1-6), a guide mechanism (1-7), a guide tube (1-8), a bearing slide (1-9), a bearing support (1-10), a conductive bearing (1-11), and a preload spring (1-12); the motor base (1-2) is fixed on the vacuum stepper motor (1-1); the insulating drive shaft (1-4) is connected to the motor shaft of the vacuum stepper motor (1-1) through the coupling (1-3); the drive wheel (1-5) is fixed on the insulating drive shaft (1-4) and fixed by a set screw; the base bracket (1-6) is fixed on the upper end of the motor base (1-2); the guide mechanism (1-7 ... is fixed on the upper end of the motor base (1-2); the guide mechanism (1-8) is fixed on the upper end of the motor base (1-2); the guide mechanism (1-9) is fixed on the upper end of the motor base (1-2); the guide mechanism (1 -7) Fixed on the base bracket (1-6), the conduit (1-8) is nested into the guide mechanism (1-7) to ensure that the two are coaxial; the bearing slide (1-9) is fixed on the motor base (1-2) and placed above the slot provided on the motor base (1-2); the bearing support (1-10) is fixed in the slide rail provided in the bearing slide (1-9) and can move left and right in the slide rail; the conductive bearing (1-11) is fixed on the positioning cylinder designed on the bearing support (1-10); the preload spring (1-12) is nested between the cylinder designed on the bearing slide (1-9) and the cylinder at the end of the bearing support (1-10); the pressure generated by the compression of the preload spring (1-12) enables the middle drive wheel (1-5) and the conductive bearing (1-11) to flexibly clamp the prepreg wire and transport it downward in an orderly manner.

3. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 2, characterized in that, The slot on the motor base (1-2) is located at the lower end of the threaded hole of the fixed bearing slide (1-9), and extends into a step for limiting the bearing slide (1-9) in the Z direction.

4. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 2, characterized in that, In the bearing slide (1-9): The bearing slide (1-9) is a U-shaped part with slide rails constructed on the inner walls on both sides; The cylinder on the bearing slide (1-9) is located on the inner wall of the end.

5. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 2, characterized in that, In the bearing support (1-10): The bearing support (1-10) is a U-shaped part, smaller than the bearing slide (1-9); cylinders are constructed on the outer walls on both sides of the bearing support (1-10), which can slide left and right on the slide rail of the bearing slide (1-9); The positioning cylinder on the bearing support (1-10) is located on the outer wall of the end, and is coaxial with the cylinder provided in the bearing slide (1-9); The positioning cylinders on the bearing support (1-10) are located on the inner walls on both sides, so that the inner diameter of the conductive bearing (1-11) is interference-fitted onto the positioning cylinders.

6. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 2, characterized in that, The nozzle infrared temperature measurement module (2) includes a nozzle (2-1), a flange sleeve (2-2), a large synchronous pulley (2-3), a guide tube (2-4), a bearing (2-5), an infrared camera fixing component (2-6), an infrared camera (2-7), a synchronous belt (2-8), a small synchronous pulley (2-9), and a small motor (2-10). The nozzle (2-1) is bolted to the flange sleeve (2-2). The flange sleeve (2-2) is positioned and fixed by the base extension component (3-1). The guide tube (2-4) is nested into the bushing of the flange sleeve (2-2) and contacts the upper end of the nozzle (2-1) to complete the limiting. The bearing (2-5) is sleeved on the guide tube (2-4), and the inner diameter of the bearing (2-5) is press-fitted with the guide tube (2-4), and the flange sleeve (2-2) abuts against the bearing (2-5) from below. The inner ring of the bearing (2-5) is used to limit the axial movement of the bearing (2-5); the large synchronous pulley (2-3) is matched with the outer diameter of the bearing (2-5) to achieve the axial rotation of the large synchronous pulley (2-3); the infrared camera fixing piece (2-6) is attached to the bottom of the large synchronous pulley (2-3), and the infrared camera (2-7) is connected to the positioning post of the infrared camera fixing piece (2-6) so that its lens is aligned with the nozzle (2-1); the small motor (2-10) is connected to the motor base (1-2), and a small synchronous pulley (2-9) is mounted on the motor shaft of the small motor (2-10). The synchronous belt (2-8) is fitted between the large synchronous pulley (2-3) and the small synchronous pulley (2-9). The rotation of the small motor (2-10) drives the infrared camera (2-7) to rotate around the end of the nozzle (2-1) to achieve temperature detection.

7. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 6, characterized in that, The adjustable Joule heating module (3) includes a base extension (3-1), a slider (3-2), a slider limiter (3-3), an adjusting nut (3-4), a slide rail (3-5), a positive power plug (3-6), a power interface (3-7), a brush (3-8), a negative power circular terminal (3-9), and a hexagonal nut (3-10). The power interface (3-7) is fixed to the side of the motor base (1-2), and the positive power plug (3-6) is connected to the power interface (3-7) to input current. The brush (3-8) is fixed on the motor base (1-2), and one end of the brush (3-8) contacts the power interface (3-7), while the other end contacts the conductive bearing (1-11), thus flexibly clamping the prepreg wire and inputting current. The slide rail (3-5) is fixed on the motor base (1-2), and the slider (3-2) moves up and down through the cooperation with the slide rail (3-5). The reciprocating motion drives the negative power supply circular terminal (3-9) to move and adjust the distance between the positive and negative circuits; the base extension (3-1) is fixed on the slider (3-2) and clamps the printing end through cooperation with the flange sleeve (2-2); the negative power supply circular terminal (3-9) is fitted under the nozzle (2-1), and the negative power supply circular terminal (3-9) is fastened by the thread provided at the lower end of the nozzle (2-1) and the hexagonal nut (3-10), realizing the power supply path; the slider limit (3-3) is located at the lower end of the motor base (1-2); the adjusting nut (3-4) is connected to the lower end of the motor base (1-2), and the slider limit (3-3) is moved up and down by rotating the thread of the adjusting nut (3-4), thereby adjusting the distance between the conductive bearing (1-11) and the negative power supply circular terminal (3-9), realizing adjustable Joule heating.

8. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 7, characterized in that, The conductive bearing (1-11) in the insulating wire feeding clamping mechanism module (1) is connected to the positive power supply through contact with the brush (3-8), the nozzle (2-1) is connected to the circular terminal (3-9) of the negative power supply, and the carbon fiber in the pre-impregnated wire passing between the two forms a power circuit, realizing the self-resistance internal heating of the carbon fiber, and only the pre-impregnated wire at both ends of the electrode is energized and heated.

9. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 8, characterized in that, The distance between the conductive bearing (1-11) and the drive wheel (1-5) in the insulating wire feeding clamping mechanism module (1) The prepreg wire diameter is adaptively adjusted based on the diameter of the prepreg wire at different times. The distance between the two satisfy: The distance between the conductive bearing (1-11) and the drive wheel (1-5) This refers to the gap between the outer walls of the two surfaces.

10. The end-of-line device for continuous fiber Joule self-heating thermoplastic composite additive manufacturing in a vacuum environment according to claim 9, characterized in that, The conductive bearing (1-11), nozzle (2-1) and brush (3-8) in the adjustable Joule heating module (3) are all made of conductive materials, selected from brass, bronze or silver copper, with a conductivity range of 50.0-60.0 MS / m; the conduit (1-8) is made of polytetrafluoroethylene.

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