A rotating dual magnetic field assisted DLP 3D printing device and printing method

Abstract

This invention provides a rotating dual magnetic field-assisted DLP 3D printing device and method, belonging to the field of 3D printing technology. It addresses the problem that existing permanent magnet-based 3D printing devices have simple structures, single magnetic field directions, and difficulty in obtaining composite materials with enhanced material properties. The 3D printing device includes a central 3D printing module and two opposing rotating magnetic field modules on either side. Each rotating magnetic field module includes a fixed frame, a servo motor, a drive component, and a permanent magnet mounted on the frame. The power output of the servo motor is connected to the input of the drive component, which drives the permanent magnet to rotate within the fixed frame. This invention's device can be used to manufacture functionalized components of composite materials with enhanced mechanical and magnetic properties, exhibiting strong molding capabilities and printing accuracy for complex structures.

Description

A rotating dual magnetic field-assisted DLP 3D printing device and printing method Technical Field

[0001] This invention relates to the field of 3D printing technology, and more specifically, to a rotating dual magnetic field assisted DLP 3D printing device and printing method. Background Technology

[0002] With the continuous development of modern manufacturing technology, 3D printing technology has been widely used in aerospace, biomedicine, consumer electronics, and flexible sensors due to its advantages of one-piece molding, material saving, and manufacturing of complex structures. Various 3D-printed material components need to possess excellent material properties to meet specific application requirements, such as high conductivity, biocompatibility, and mechanical properties, which places new demands on 3D printing equipment and methods.

[0003] 3D printing technology can be categorized into seven different processes: material jetting, material extrusion, photopolymerization, binder jetting, powder bed fusion (PBF), energy deposition, and sheet lamination. From these methods, several commonly used 3D printing technologies for polymer-based composite materials have emerged, such as direct ink writing (DIW), fused deposition modeling (FDM), stereolithography (SLA), two-photon polymerization (TPP), and inkjet printing (IJP). These manufacturing methods are widely applicable to the molding of polymers, ceramics, and composite materials; each technology has its advantages and limitations when constructing objects with specific structures and functions. For example, IJP (Integrated Photopolymer Printing) is characterized by its high-resolution printing capabilities, but it is typically only used for printing small parts; FDM (Fiber Direct Printing) is one of the most commonly used 3D printing technologies for thermoplastic polymers, but its printing accuracy is low and the raw material preparation process is cumbersome; DIW (Digital Direct Printing) uses the mechanical extrusion principle, has simple equipment, good polymer selection and multi-material printability, but also has low printing accuracy and high requirements for the rheological properties of the printing ink; TPP (Transmission Photopolymerization) is a relatively new 3D printing process based on SLA (Surface Laser Lamination), which provides a way to activate the chemical or physical processes of materials at a high spatial resolution (100nm) in three dimensions, enabling micro / nano manufacturing, but the size of printed components is limited to the micrometer level; while DLP (Digital Photopolymerization) 3D printing technology, using surface projection, can achieve rapid and large-area manufacturing, and the raw material cost of photosensitive resin is low, with strong development potential, and it has developed rapidly in recent years. Currently, although permanent magnet-based 3D printing devices have high magnetic field strength, their simple structure and unidirectional magnetic field make it difficult to obtain composite materials with enhanced material properties, and they cannot simultaneously achieve both printing speed and accuracy. Summary of the Invention

[0004] The technical problem to be solved by this invention is:

[0005] Existing 3D printing devices based on permanent magnets have simple structures and single magnetic field directions, making it difficult to obtain composite materials with enhanced material properties.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] This invention provides a rotating dual magnetic field assisted DLP 3D printing device. The 3D printing device includes a 3D printing module located in the middle and rotating magnetic field modules located on both sides opposite each other. Each rotating magnetic field module includes a fixed frame and a servo motor, a drive component and a permanent magnet on the fixed frame. The power transmission of the servo motor is connected to the input end of the drive component, and the drive component is used to drive the permanent magnet to rotate within the fixed frame.

[0008] Furthermore, the 3D printing module includes a resin tank, an L-shaped printing platform, a linear module, a limit switch, a stepper motor, a DLP light source, a reflector assembly, and a support frame;

[0009] The support frame includes a printing module support frame and a rotating magnetic field module support frame. The printing module support frame includes a base frame and a side frame. The resin tank is installed on the upper end of the base frame. The two rotating magnetic field modules are installed on the upper end of the rotating magnetic field module support frame and are located opposite each other on both sides of the resin tank. The bottom of the L-shaped printing platform is adapted to the inner cavity of the resin tank and is parallel to the bottom of the resin tank. The linear module includes a movable slider and a slide rail. The linear module is installed vertically on the side frame. The upper end of the L-shaped printing platform is connected to the slider of the linear module. The stepper motor is installed on the side frame and is used to drive the slider to move along the slide rail, further driving the L-shaped printing platform to move vertically. The DLP light source is installed on the side frame and is located below the resin tank. The DLP light source is used to emit patterned light. The reflector is installed in front of the DLP light source and is used to reflect the patterned light emitted by the DLP light source to the bottom of the resin tank.

[0010] Furthermore, the 3D printing module also includes a photoelectric limit switch, which is installed on one side of the slide rail and is used to limit the position of the L-shaped printing platform after the first layer is printed.

[0011] Furthermore, the rotating magnetic field module is also provided with a magnetic field stabilizing block, the bottom of which is connected to the upper end of the rotating magnetic field module support frame, and the side wall of which is connected to the fixed frame.

[0012] Furthermore, the permanent magnet is a vertically mounted cylindrical permanent magnet with radial magnetization. The servo motor rotates through the drive component, further driving the permanent magnet to rotate around the axial direction.

[0013] Furthermore, the distance between the two permanent magnets arranged opposite each other is 60-300mm.

[0014] Furthermore, the servo motor speed is not less than 100 rpm.

[0015] Furthermore, the method for determining the minimum speed of the servo motor is as follows: based on the force conditions of the disk-shaped magnetic particles in the liquid resin, without considering the gravitational torque T. g The effect of considering the viscous torque T under steady rotational conditions. η With magnetic torque T m In equilibrium, i.e., T η +T m =0, substituting formulas (1) and (2) into the torque balance equation, and according to the phase lag formula (3), the critical speed threshold shown in formula (4) is obtained:

[0016]

[0017]

[0018]

[0019]

[0020] Where μ0 is the free permeability, χ ps η is the magnetic permeability of the magnetic filler, d is the thickness of the magnetic layer, η is the resin viscosity, H0 is the intensity of the rotating magnetic field, a is half the thickness of the magnetic disk particles, b is the radius of the magnetic disk particles, f and f0 are both Perrin friction coefficients, and φ is the magnetic permeability of the magnetic filler. p Let θ be the angle between the magnetic disk particle and the direction of gravity, θ be the angle between the magnetic field and the diameter direction of the magnetic disk particle, and ω be the rotational speed of the magnetic field. c The critical revolutions required for the magnetic field to align.

[0021] A 3D printing method using the rotating dual magnetic field assisted DLP 3D printing device described in the above technical solution includes the following steps:

[0022] Step 1: Prepare magnetic resin material and store the prepared resin material in a dark environment away from light for later use;

[0023] Step 2: Adjust the distance between the permanent magnets at both ends of the resin tank to determine the magnetic field strength and set the rotation speed of the servo motor; place the resin material in the resin tank, and before starting the actual printing, turn on the servo motors on both sides to generate a rotating magnetic field at the preset rotation speed to pre-magnetize and align the magnetic particles.

[0024] Step 3: Import the 3D printing model file into the slicing software, set the exposure time and layer thickness; the DLP light source projects patterned light onto the bottom of the resin tank through the reflector component to form a curing layer. After the single layer is cured, the stepper motor drives the L-shaped printing platform to move upward by one layer thickness. The DLP light source continues to project and cure. This cycle is repeated until the printing of the entire 3D model is completed, and finally, a reinforced composite material print with magnetic particles oriented is obtained.

[0025] Further, the preparation method of the magnetic resin material in step 1 is as follows: 86 parts of FormlabsCleaner V4 resin are weighed as the matrix resin, and 5 parts of carbonyl iron powder are added as magnetic particles, 1 part of TPO as a photoinitiator, 2 parts of BYK 163 dispersant and 6 parts of nano silica powder as rheology modifiers. After stirring and ultrasonic dispersion, a uniformly dispersed magnetic photosensitive resin is obtained.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] This invention discloses a rotating dual magnetic field assisted DLP 3D printing device and printing method. The DLP 3D device based on the dual rotating magnetic field assisted by permanent magnets can be used to manufacture functionalized components of composite materials with enhanced mechanical and magnetic properties, and has strong molding capability and printing accuracy for complex structures.

[0028] The rotating dual magnetic field DLP 3D printing device of the present invention has the advantages of low maintenance cost, simple structure and high magnetic alignment efficiency.

[0029] The 3D printing device of this invention has a certain degree of adaptability to various types and concentrations of material systems, providing a new process approach for improving the performance of composite materials. Attached Figure Description

[0030] Figure 1 is a schematic diagram of the structure of the rotating dual magnetic field assisted DLP 3D printing device in an embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of the rotating magnetic field module structure in an embodiment of the present invention;

[0032] Figure 3 is a schematic diagram of the 3D printing module structure in an embodiment of the present invention;

[0033] Figure 4 is a schematic diagram of the structure of the rotating magnetic field module with opposite orientation in an embodiment of the present invention;

[0034] Figure 5 is a torque analysis diagram of the disc-shaped magnetic particles in liquid resin in an embodiment of the present invention.

[0035] Figure 6 is a schematic diagram of the dual synchronous rotating magnetic field in an embodiment of the present invention;

[0036] Figure 7 shows the alignment state of magnetic particles in the magnetic photosensitive resin under a rotating magnetic field in an embodiment of the present invention.

[0037] Figure 8 shows the results of wear resistance test and magnetic anisotropy test of printed parts under different carbonyl iron powder addition amounts in the embodiments of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1-Base frame, 2-Rotating magnetic field module support frame, 3-Magnetic field stabilizing block, 4-Permanent magnet, 5-Resin tank, 6-Fixed frame, 7-L-shaped printing platform, 8-Side frame, 9-Linear module, 10-Limit switch, 11-Stepper motor, 12-DLP light source, 13-Reflector assembly, 14-Servo motor. Detailed Implementation

[0040] In the description of this invention, it should be noted that the terms used in the various embodiments, such as "upper," "lower," "front," "rear," "left," and "right," which indicate orientation, are only used to simplify the description of the positional relationships based on the accompanying drawings and do not mean that the components and devices referred to must be operated in accordance with the specific orientations and defined operations, methods, and structures in the specification. Such directional terms do not constitute a limitation of this invention.

[0041] In the description of this invention, it should be noted that the terms "first," "second," and "third" mentioned in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] Specific Implementation Scheme 1: As shown in Figures 1, 2 and 4, the present invention provides a rotating dual magnetic field assisted DLP 3D printing device. The 3D printing device includes a 3D printing module located in the middle and rotating magnetic field modules located on both sides opposite to each other. Each rotating magnetic field module includes a fixed frame 6 and a servo motor 14, a drive component and a permanent magnet 4 on the fixed frame 6. The power transmission of the servo motor 14 is connected to the input end of the drive component. The drive component is used to drive the permanent magnet 4 to rotate within the fixed frame 6.

[0044] In this implementation scheme, the magnetic field strength can be controlled by adjusting the distance between two oppositely positioned magnetic field modules.

[0045] Specific implementation scheme 2: As shown in Figure 3, the 3D printing module includes a resin tank 5, an L-shaped printing platform 7, a linear module 9, a limit switch 10, a stepper motor 11, a DLP light source 12, a reflector assembly 13, and a support frame;

[0046] The support frame includes a printing module support frame and a rotating magnetic field module support frame 2. The printing module support frame includes a base frame 1 and a side frame 8. The resin tank 5 is installed on the upper end of the base frame 1. The two rotating magnetic field modules are installed on the upper end of the rotating magnetic field module support frame 2 and are located opposite each other on both sides of the resin tank 5. The bottom of the L-shaped printing platform 7 is adapted to the inner cavity of the resin tank 5 and is parallel to the bottom of the resin tank 5. The linear module 9 includes a movable slider and a slide rail. The linear module 9 is installed vertically on the side frame 8. The upper end of the L-shaped printing platform 7... The stepper motor 11, connected to the slider of the linear module 9, is mounted on the side frame 8 and connected to the slider via a ball screw. The stepper motor 11 drives the slider to move along the slide rail, further driving the L-shaped printing platform 7 to move vertically. The DLP light source 12 is mounted on the side frame 8 and located below the resin tank 5. The DLP light source 12 emits patterned light. The reflector assembly 13 is mounted in front of the DLP light source 12 to reflect the patterned light emitted by the DLP light source 12 to the bottom of the resin tank 5. Other aspects of this embodiment are the same as in specific embodiment one.

[0047] In this implementation scheme, the linear module is selected from the HKK8610C-640-A1 model of HIWIN linear modules.

[0048] Specific Implementation Scheme 3: The 3D printing module also includes a photoelectric limit switch, which is installed on one side of the slide rail to limit the upward position of the L-shaped printing platform 7 after the first layer is printed. All other aspects of this implementation scheme are the same as in Specific Implementation Scheme 2.

[0049] In this embodiment, the slider of the linear module 9 is equipped with a photoelectric limit switch baffle. After the first layer is printed, the printing platform 7 rises by one layer thickness. When the photoelectric limit switch detects the baffle, it sends a signal command to control the stepper motor to stop moving, which is used to prevent the L-shaped printing platform from colliding with the bottom of the resin tank 5.

[0050] Specific Implementation Scheme Four: The rotating magnetic field module is further provided with a magnetic field stabilizing block 3. The bottom of the magnetic field stabilizing block 3 is connected to the upper end of the rotating magnetic field module support frame 2, and the side wall of the magnetic field stabilizing block 3 is connected to the fixed frame 6. All other aspects of this implementation scheme are the same as in Specific Implementation Scheme Three.

[0051] Specific Implementation Scheme 5: The permanent magnet 4 is a vertically mounted cylindrical permanent magnet, and the magnetization direction is radial. The servo motor 14 rotates through the drive component, further driving the permanent magnet 4 to rotate around the axial direction. All other aspects of this implementation scheme are the same as in Specific Implementation Scheme 1.

[0052] Specific Implementation Scheme Six: The distance between the two oppositely positioned permanent magnets 4 is 60-300mm. All other aspects of this scheme are the same as Specific Implementation Scheme One.

[0053] Specific Implementation Scheme Seven: The rotational speed of servo motor 14 is not less than 100 rpm. All other aspects of this implementation scheme are the same as Specific Implementation Scheme One.

[0054] Specific implementation plan eight: The method for determining the minimum speed of the servo motor 14 is as follows: As shown in Figure 5, the disc-shaped magnetic particles in the liquid resin will be subjected to a gravitational torque T. g Viscous torque T η and magnetic torque T m Function, of which T g Relative to T m The difference is more than two orders of magnitude smaller, therefore T is not considered. g The function of T. m and T η The calculation formulas are shown in formulas (1) and (2), considering the viscous torque T under steady rotation. η With magnetic torque T m In equilibrium, i.e., T η +T m =0, substituting formulas (1) and (2) into the torque balance equation, and according to the phase lag formula (3), the critical speed threshold shown in formula (4) is obtained:

[0055]

[0056]

[0057]

[0058]

[0059] Where μ0 is the free permeability, χ ps η is the magnetic permeability of the magnetic filler, d is the thickness of the magnetic layer, η is the resin viscosity, H0 is the intensity of the rotating magnetic field, a is half the thickness of the magnetic disk particles, b is the radius of the magnetic disk particles, f and f0 are both Perrin friction coefficients, and φ is the magnetic permeability of the magnetic filler. pLet θ be the angle between the magnetic disk particle and the direction of gravity, θ be the angle between the magnetic field and the diameter direction of the magnetic disk particle, and ω be the rotational speed of the magnetic field. c The critical revolutions required for magnetic field alignment. This implementation scheme is otherwise identical to specific implementation scheme seven.

[0060] When the rotation speed is low, the particles will rotate with the magnetic field and the rotation period is consistent. As the motor speed increases, the particles will be unable to keep up with the "pace" of the magnetic field and will remain stationary, tending to the state of minimum magnetic field energy, thus achieving the alignment of magnetic particles.

[0061] This invention utilizes a permanent magnet combined with a servo motor, offering advantages such as high control precision, low maintenance costs, and stable operation. The magnetic field can be steplessly adjusted from 0.8mT to 300mT, adapting to different magnetically responsive material systems. The servo motor speed can be arbitrarily adjusted from 100 to 3000 RPM, enhancing the driving effect.

[0062] Specific Implementation Plan Nine: A 3D printing method, comprising the following steps:

[0063] Step 1: Prepare magnetic resin material and store the prepared resin material in a dark environment away from light for later use;

[0064] Step 2: Adjust the distance between the permanent magnets at both ends of the resin tank to determine the magnetic field strength, and set the rotation speed of the servo motor 14; place the resin material in the resin tank, and before starting the actual printing, turn on the servo motors 14 on both sides to generate a rotating magnetic field at the preset rotation speed to pre-magnetize and align the magnetic particles.

[0065] Step 3: Import the 3D printing model file into the slicing software, set the exposure time and layer thickness; the DLP light source 12 projects patterned light onto the bottom of the resin tank through the reflector component 13 to form a curing layer. After the single layer is cured, the stepper motor 11 drives the L-shaped printing platform 7 to move upward by one layer thickness. The DLP light source 12 continues to project and cure. The operation is repeated until the printing of the entire three-dimensional model is completed, and finally a reinforced composite material print with magnetic particles oriented is obtained.

[0066] Specific Implementation Scheme Ten: The preparation method of the magnetic resin material is as follows: 86 parts by weight of Formlabs Cleaner V4 resin are weighed as the matrix resin. 5 parts of carbonyl iron powder are added sequentially as magnetic particles, 1 part of TPO as a photoinitiator, 2 parts of BYK 163 dispersant, and 6 parts of nano-silica powder as a rheology modifier. After stirring and ultrasonic dispersion, a uniformly dispersed magnetic photosensitive resin is obtained. Other aspects of this implementation scheme are the same as in Specific Implementation Scheme Nine.

[0067] Example 1

[0068] Step 1: Preparation of magnetic resin material: Weigh 86 parts of Formlabs CleanerV4 resin as the matrix resin, add 5 parts of carbonyl iron powder (d50 = 5um) as magnetic particles, 1 part of TPO as photoinitiator, 2 parts of BYK 163 dispersant and 6 parts of nano silica powder as rheology modifier. After stirring and ultrasonic dispersion, a uniformly dispersed magnetic photosensitive resin is obtained and stored in the dark.

[0069] Step 2: As shown in Figures 6 and 7, cylindrical radially magnetized permanent magnets (NdFeB magnets, N52 grade, remanence 1.43T) are used. They are installed with the magnetic poles NS and NS respectively. The distance between the two permanent magnets is adjusted to 240mm, which can generate a magnetic field strength of about 11.3mT. The rotation speed of the servo motor 14 is set. The resin material is placed in the resin tank. Before the formal printing begins, the servo motors 14 on both sides are turned on to generate a rotating magnetic field at the preset rotation speed to pre-magnetize and align the magnetic particles.

[0070] Step 3: Import the .stl 3D printing model file into the slicing software. The 3D model is sliced ​​into a series of 2D images, each representing a cross-section during printing. Set the exposure time to 12s and the layer thickness to 50μm. Use a 405nm UV light engine as the DLP light source. The patterned ultraviolet light emitted by the UV light engine is projected onto the bottom of the resin tank through the reflector component 13. The bottom of the resin tank is a transparent plate. The light passes through the bottom of the resin tank, causing the photosensitive resin material to form a cured layer. After the single layer is cured, the stepper motor 11 drives the L-shaped printing platform 7 to move upward by one layer thickness. The DLP light source 12 continues to project and cure. Repeat the operation until the printing of the entire 3D model is completed, and finally, a reinforced composite material print with magnetic particles oriented is obtained.

[0071] In this embodiment, the exposure time is 12 seconds during the printing process, which enables efficient printing of reinforced composite material parts.

[0072] Wear resistance and magnetic anisotropy were tested on printed parts with different amounts of carbonyl iron powder. Specifically, after printing, the samples were cleaned with ethanol or isopropanol and then placed in a form cure for secondary UV exposure and post-heating treatment at 60℃. The test results are shown in Figure 8. It can be seen that the directional arrangement of carbonyl iron powder particles can effectively improve wear resistance and magnetic anisotropy; at the same time, it has the ability to form complex components and printing accuracy, with a minimum feature resolution better than 100μm.

[0073] This invention applies to a wide range of material systems and has broad applicability. Besides acting on traditional magnetic material systems (such as iron oxide and neodymium iron boron), the magnetic field can also be used to distribute magnetized non-magnetic materials (such as iron oxide-modified alumina and carbon nanotubes), thus expanding its application scope. Furthermore, combined with material magnetization technology, it can be used to manufacture various composite components with enhanced properties, such as those for increasing ceramic hardness, unidirectional conductive materials, and shape memory polymers.

[0074] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A rotating dual magnetic field-assisted DLP 3D printing device, characterized in that, The 3D printing device includes a 3D printing module in the middle and two rotating magnetic field modules arranged opposite each other on both sides. Each rotating magnetic field module includes a fixed frame (6) and a servo motor (14), a drive component, and a permanent magnet (4) on the fixed frame (6). The power output end of the servo motor (14) is connected to the input end of the drive component. The drive component is used to drive the permanent magnet (4) to rotate within the fixed frame (6). The 3D printing module includes a resin tank (5), an L-shaped printing platform (7), a linear module (9), a limit switch (10), a stepper motor (11), a DLP light source (12), a reflector assembly (13), and a support frame. The support frame includes a printing module support frame and a rotating magnetic field module support frame (2). The printing module support frame includes a base frame (1) and a side frame (8). The resin tank (5) is installed on the upper end of the base frame (1). The two rotating magnetic field modules are installed on the rotating magnetic field module support frame. The upper end of the frame (2) is located on both sides of the resin tank (5). The bottom of the L-shaped printing platform (7) is adapted to the inner cavity of the resin tank (5) and parallel to the bottom of the resin tank (5). The linear module (9) includes a slider and a slide rail that are movably connected. The linear module (9) is installed on the side frame (8) in the vertical direction. The upper end of the L-shaped printing platform (7) is connected to the slider of the linear module (9). The stepper motor (11) is installed on the side frame (8). The stepper motor (11) is used to drive the slider to move along the slide rail, and further drive the L-shaped printing platform (7) to move in the vertical direction. The DLP light source (12) is installed on the side frame (8) and located below the resin tank (5). The DLP light source (12) is used to emit patterned light. The reflector (13) is installed in front of the DLP light source (12) and is used to reflect the patterned light emitted by the DLP light source (12) to the bottom of the resin tank (5).

2. The rotating dual magnetic field assisted DLP 3D printing device according to claim 1, characterized in that, The 3D printing module also includes a photoelectric limit switch, which is installed on one side of the slide rail and is used to limit the position of the L-shaped printing platform (7) after the first layer is printed.

3. The rotating dual magnetic field assisted DLP 3D printing device according to claim 2, characterized in that, The rotating magnetic field module is also provided with a magnetic field stabilizing block (3). The bottom of the magnetic field stabilizing block (3) is connected to the upper end of the rotating magnetic field module support frame (2), and the side wall of the magnetic field stabilizing block (3) is connected to the fixed frame (6).

4. The rotating dual magnetic field assisted DLP 3D printing device according to claim 1, characterized in that, The permanent magnet (4) is a vertically mounted cylindrical permanent magnet with radial magnetization. The servo motor (14) rotates through the drive component, which in turn drives the permanent magnet (4) to rotate around the axis.

5. The rotating dual magnetic field assisted DLP 3D printing device according to claim 1, characterized in that, The distance between the two permanent magnets (4) set opposite to each other is 60-300 mm.

6. The rotating dual magnetic field assisted DLP 3D printing device according to claim 1, characterized in that, The servo motor (14) has a rotational speed of not less than 100 rpm.

7. The rotating dual magnetic field assisted DLP 3D printing device according to claim 6, characterized in that, The method for determining the minimum speed of the servo motor (14) is as follows: based on the force situation of the disc-shaped magnetic particles in the liquid resin, without considering the gravitational torque T. g The effect of considering the viscous torque T under steady rotational conditions. η With magnetic torque T m In equilibrium, i.e., T η +T m =0, substitute formulas (1) and (2) into the torque balance equation, and according to the phase lag formula (3), obtain the critical speed threshold as shown in formula (4): （1） （2） （3） (4) Among them, The permeability of free space, Let d be the magnetic permeability of the magnetic particles, and d be the thickness of the magnetic layer. Let be the resin viscosity, H0 be the rotating magnetic field strength, a be half the thickness of the magnetic disk particle, b be the radius of the magnetic disk particle, and f and f0 be the Perrin friction coefficients. The angle between the magnetic disk particle and the direction of gravity is denoted as . The angle between the magnetic field and the diameter direction of the magnetic disk particle. The rotational speed of the magnetic field. The critical revolutions required for the magnetic field to align.

8. A 3D printing method using the rotating dual magnetic field assisted DLP 3D printing apparatus according to any one of claims 1 to 7, characterized in that, The process includes the following steps: Step 1: Prepare magnetic resin material and store the prepared resin material in a dark environment to prevent light from entering. Step 2: Adjust the distance between the permanent magnets at both ends of the resin tank to determine the magnetic field strength and set the rotation speed of the servo motor (14). Place the resin material in the resin tank and turn on the servo motors (14) on both sides to generate a rotating magnetic field at the preset rotation speed before starting the formal printing. This will pre-magnetize and align the magnetic particles. Step 3: Import the 3D printing model file into the slicing software and set the exposure time and layer thickness. The DLP light source (12) projects patterned light onto the bottom of the resin tank through the reflector (13) to form a cured layer. After the single layer is cured, the stepper motor (11) drives the L-shaped printing platform (7) to move upward by one layer thickness. The DLP light source (12) continues to project and cure the light. This process is repeated until the printing of the entire three-dimensional model is completed, and finally, a reinforced composite material print with oriented magnetic particles is obtained.

9. The 3D printing method according to claim 8, characterized in that, The preparation method of the magnetic resin material in step 1 is as follows: 86 parts of Formlabs Cleaner V4 resin are weighed as the matrix resin, and 5 parts of carbonyl iron powder are added as magnetic particles, 1 part of TPO as photoinitiator, 2 parts of BYK 163 dispersant and 6 parts of nano silica powder as rheology modifier. After stirring and ultrasonic dispersion, a uniformly dispersed magnetic photosensitive resin is obtained.

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