3D printing system and 3D printing method based on microwave heating

Abstract

The invention discloses a 3D printing system and method based on microwave heating, and relates to the technical field of additive manufacturing. Comprising a 3D printing lifting platform, a powder supply and laying system for laying or spraying powder on the 3D printing lifting platform, an antenna mounting frame arranged on the 3D printing lifting platform in a sliding mode, an antenna array heating module arranged below the antenna mounting frame and a spraying assembly for spraying a wave absorbing agent. The antenna array heating module comprises a dielectric plate, at least two rows of patch antenna assemblies which are transversely arranged are arranged on the dielectric plate, each row of patch antenna assemblies comprises a plurality of patch units which are arranged at intervals, and the patch units of every two adjacent rows of patch antenna assemblies are arranged in a staggered mode. And the projections of all the patch units on the front and back rows of patch antenna assemblies in the longitudinal direction are partially overlapped. The wave-absorbing material is selectively sprayed on the powder layer through the spraying assembly, and in combination with radiation heating of the movable antenna array, rapid, uniform and local selective melting of polymer powder is achieved, and the printing efficiency and the forming quality are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing technology, more particularly to the field of 3D printing system and 3D printing method based on microwave heating. BACKGROUND

[0002] 3D printing, also known as additive manufacturing, is a technology that constructs three-dimensional objects by layering materials, while a 3D printer is an extension of this planar printing principle to the third dimension. The printer starts printing layer by layer according to the instructions generated by slicing software, and finally these thin layers are stacked into a solid three-dimensional object. There are several different 3D printing technologies suitable for different materials and application scenarios. The most common ones are as follows: Fused deposition modeling (FDM): a hot thermoplastic material filament (such as PLA, ABS) is fed into a heated print head, which is melted and then extruded like toothpaste, layer by layer, to build up on the print platform. The advantages of this 3D printing method are low machine and material cost, simple operation, variety of materials, safety and environmental protection. The disadvantages are layer lines on the surface, relatively low precision, and slow speed. It is the most popular consumer-level 3D printing technology, commonly used for prototype verification, education, and DIY creation.

[0003] Selective laser sintering (SLS): uses a high-power laser to sinter and fuse tiny nylon or other plastic powder particles together to form a solid structure. The unsintered powder naturally becomes a support, allowing for the printing of very complex structures. The advantages are high strength, no need for support structures, ability to manufacture complex geometries, and good material performance. The disadvantages are high equipment and material costs, large machine size, and rough surface. It is mainly used in industrial applications for manufacturing functional prototypes and final-use parts.

[0004] On some high-end or self-made printers, an independent infrared heater is also used to irradiate the upper part of the part being printed to reduce interlayer cooling stress during printing, further improve printing quality, and prevent warping (especially when printing ABS and other materials that are prone to shrinkage).

[0005] The infrared heater has weak penetration ability in high molecular powder, so the penetration speed is slow and the interlayer strength is low; the infrared heater has a long energy transfer path and large thermal inertia, which leads to high overall energy consumption and easy introduction of thermal stress in order to maintain a local high temperature; the infrared heater does not support high temperatures, such as peek materials that cannot be heated to the corresponding temperature.

[0006] Therefore, developing a new molding technology that can achieve local precise heating, improve efficiency from the source of energy conversion, be selective, have strong penetration, and be suitable for high temperatures, has become the key to breaking through the high energy consumption dilemma of existing technologies. SUMMARY

[0007] The present application aims at solving the above technical problems, and provides a 3D printing system and a 3D printing method based on microwave heating.

[0008] In order to achieve the above-mentioned purposes, the present application specifically adopts the following technical solutions: The first aspect of the present application provides a 3D printing system based on microwave heating, which comprises a 3D printing lifting platform, a powder supply and laying system for laying or spraying powder on the 3D printing lifting platform, an antenna mounting rack slidingly arranged on the 3D printing lifting platform, and an antenna array heating module arranged below the antenna mounting rack. The antenna array heating module comprises a dielectric plate, at least two rows of transversely arranged patch antenna assemblies arranged on the dielectric plate, each row of patch antenna assemblies comprising a plurality of patch units arranged at intervals, the patch units of the adjacent two rows of patch antenna assemblies being arranged in a staggered manner, and the projections of all the patch units on the front and rear two rows of patch antenna assemblies in the longitudinal direction being partially overlapped.

[0009] In one embodiment, each patch unit comprises a metal ground layer arranged above the dielectric plate, a metal patch layer corresponding to the position of the metal ground layer arranged below the dielectric plate, a coaxial feed port arranged on the metal ground layer, and a microwave source connected to each coaxial feed port through a coaxial feed line. The outer conductor of the coaxial feed port is welded on the metal ground layer. The inner conductor of the coaxial feed port is welded on the metal patch layer through the dielectric plate.

[0010] In one embodiment, two rows of transversely arranged patch antenna assemblies are arranged on the dielectric plate, and each row of patch antenna assemblies comprises a plurality of patch units arranged at equal intervals in the transverse direction.

[0011] In one embodiment, the temperature main control system comprises a temperature sensor array or an infrared imager array for detecting the temperature of the powder to be 3D printed on the 3D printing lifting platform, a main control unit, and a data display interface, the temperature sensor array or the infrared imager array is signal connected with the main control unit, and the main control unit is signal connected with the microwave source and the data display interface.

[0012] In one embodiment, the powder supply and laying system comprises a powder supply system and a powder recovery system arranged on both sides of the 3D printing lifting platform in the transverse direction, further comprises a powder laying module for laying the powder in the powder supply system to the 3D printing lifting platform in the transverse direction, and a spraying assembly arranged on the antenna mounting rack and spraying the wave absorber on the 3D printing lifting platform. The antenna mounting rack is slidingly arranged on the 3D printing lifting platform in the longitudinal direction.

[0013] In one embodiment, the powder supply system includes a powder supply box with an opening at the top. The powder supply box includes a powder supply box side wall and a powder supply box bottom plate that is movably sealed inside the powder supply box side wall. A vertical lifting mechanism is provided at the bottom of the powder supply box bottom plate to drive the powder supply box bottom plate to rise and lower and control the lifting stroke. The powder spreading module includes two transverse guide rails arranged horizontally on both sides of the powder supply box and the 3D printing lifting platform, a powder spreading mounting frame set on the two transverse guide rails and reciprocating along the two transverse guide rails, and a powder spreading roller installed longitudinally on the powder spreading mounting frame. The antenna mounting bracket includes a gate-shaped mounting base that slides longitudinally, two longitudinal mounting plates mounted on the gate-shaped mounting base via a lifting module, a first transverse mounting rod and a second transverse mounting rod connected between the two longitudinal mounting plates, a spraying assembly that slides on the first transverse mounting rod, and an antenna array heating module that is fixedly mounted on the bottom of the second transverse mounting rod.

[0014] In one embodiment, the antenna mounting frame includes two guide rails arranged longitudinally on both sides of the 3D printing lifting platform, a movable frame arranged above the 3D printing lifting platform and reciprocating along the two guide rails, a first linear drive mechanism for driving the movable frame to move horizontally, a working mounting frame capable of moving up and down along the vertical direction of the movable frame, and a second linear drive mechanism for driving the working mounting frame to move up and down vertically. The powder supply and application system includes a powder spraying module and a spraying assembly mounted on a work mounting frame; The antenna array heating module is mounted on the work mounting frame; The powder spraying module, spraying components, and antenna array heating module are arranged longitudinally on the work mounting frame.

[0015] A second aspect of the present invention provides a microwave-heated planar powder 3D printing method, employing the aforementioned microwave-heated 3D printing system, comprising the following steps: S1. The powder supply system raises a layer of powder, and the powder spreading module spreads a layer of powder on the 3D printing lifting platform. S2. The spraying component then sprays adhesive or microwave absorber onto the powder on the 3D printing lifting platform; S3. Turn on the antenna array heating module. The antenna array heating module moves longitudinally to the adhesive area that needs to be heated and heats that area. S4. Monitor the local temperature through a temperature sensor array or infrared imager array and feed it back to the main control unit; S5. The main control unit adjusts the activation, power, and phase of the antenna array heating module according to the heating requirements to achieve local heating and avoid stress concentration. S6. The antenna array heating module moves longitudinally with the spraying component to achieve dynamic heating along the 3D printing trajectory; S7. Repeat steps S1 to S6, printing layer by layer until the part is complete.

[0016] In one implementation, in step S5, the main control unit uses a PID algorithm to regulate the input power of the antenna array heating module: when the temperature is lower than or reaches the target temperature, the input power is kept constant at 150W; when the temperature exceeds the target temperature, the input power is reduced.

[0017] A third aspect of the present invention provides a microwave-heated powder spraying 3D printing method, employing the aforementioned microwave-heated 3D printing system, comprising the following steps: S1. The powder spraying module first sprays a layer of powder onto the 3D printing lifting platform; S2. The spraying component then sprays adhesive or microwave absorber onto the powder on the 3D printing lifting platform; S3. Turn on the antenna array heating module. The antenna array heating module moves longitudinally to the adhesive area that needs to be heated and heats that area. S4. Monitor the local temperature using a temperature sensor or infrared imaging and feed it back to the control system; S5. The control system adjusts the activation, power, and phase of the antenna array heating module according to the heating requirements to achieve localized heating and avoid stress concentration. S6. The antenna array heating module moves longitudinally with the spraying component to achieve dynamic heating along the 3D printing trajectory; S7. Repeat steps S1 to S6, printing layer by layer until the part is complete.

[0018] The beneficial effects of this invention are as follows: 1. This invention selectively sprays microwave absorbing material onto the powder layer using a spraying component, combined with radiant heating from a movable antenna array, to achieve rapid, uniform, and locally selective melting of polymer powder, effectively improving printing efficiency and molding quality.

[0019] 2. Heating Efficiency Advantage: From layer-by-layer scanning to bulk manufacturing, the speed advantage of microwaves stems from their unique volumetric heating (or "bulk heating") mechanism. Traditional infrared 3D printing technology relies on heat conduction, with energy transferred from the material surface inwards. This heating method limits the melting or sintering of each powder layer to the layers directly irradiated by infrared light and the interface with the already solidified parts below, essentially making it a layer-by-layer process. Microwaves, however, can penetrate the interior of the material, directly converting electromagnetic energy into heat energy throughout the entire powder area. This means that in a microwave field, energy can act simultaneously on multiple newly laid powder layers, not just the surface layers. This capability makes it possible for microwave 3D printing to achieve "bulk manufacturing," that is, solidifying a three-dimensional volume in one go, thus overcoming the efficiency bottleneck of traditional point-by-point scanning and layer-by-layer accumulation, and providing potential for the rapid prototyping of large-sized parts.

[0020] 3. Advantages in energy efficiency: Precise energy utilization. The excellent performance of microwaves in terms of energy consumption is mainly due to two characteristics: selective heating and volume heating.

[0021] Selective Heating and Power Requirements: Microwave energy is not uniformly absorbed by all materials; it is primarily absorbed by materials or components with specific dielectric losses (high loss factors), such as polar molecules, moisture, or specific additives within the material. This selectivity means that energy can be used efficiently when heating such materials without first heating the entire build cavity or surrounding environment. Therefore, to raise materials to the same processing temperature, microwave systems typically require less effective power than infrared-based systems, where a significant amount of energy is consumed in heating the surrounding environment, cavity, or gaseous environment, rather than being used entirely for the target material.

[0022] Highly efficient energy conversion and low heat loss: Microwave heating is a "bulk heat source" where electromagnetic energy causes the molecules inside the material to oscillate at high frequencies, generating heat directly within the material itself. In contrast, traditional methods such as infrared heating require high-temperature heat sources, and energy is transferred from the outside to the inside through thermal radiation and conduction. During this process, a considerable portion of the energy is dissipated in the heating environment, carrier gas, or equipment components.

[0023] 3. Compared to infrared heating technology, this invention is suitable for high-temperature printing, specifically as follows: Infrared technology faces multiple limitations when reaching high temperatures, mainly due to its energy transfer method and the inherent characteristics of material interactions. Infrared heating relies on electromagnetic radiation for heat transfer, and the achievable temperature is highly dependent on the power density of the emission source and the absorption efficiency of the heated material for a specific infrared wavelength. If the wavelength of the infrared radiation does not match the optimal absorption band of the material, a large amount of energy will be reflected or transmitted instead of being absorbed and converted into heat energy, which directly limits the heating potential. Even with the use of higher-power near-infrared technology, if the surface of the heated object is smooth, light-colored, or has poor thermal conductivity and rapid heat dissipation, it will be difficult to accumulate heat, making it difficult to achieve and maintain a stable high-temperature state. Theoretically, by greatly increasing the power, the upper limit of infrared heating temperature can be very high, but in practical industrial applications, due to limitations in equipment cost, safety, and material tolerance, achieving a uniform, efficient, and controllable ultra-high temperature environment remains a challenge. Microwaves can achieve ultra-high temperature processing mainly due to their volumetric heating mechanism. Microwave energy can penetrate materials and be directly converted into heat energy inside the material, thereby achieving rapid overall heating.

[0024] 4. The present invention achieves better interlayer bonding quality and deep fusion, as detailed below: Penetrating heating improves adhesion: In powder bed 3D printing, infrared heating, due to its limited penetration depth, concentrates heat primarily on the surface of the newly laid powder layer. This may result in insufficient temperature at the interface between the new powder layer and the underlying solidified solid to achieve adequate molecular diffusion and fusion, leading to relatively weak interlayer adhesion (e.g., ...). Figure 11 (As shown).

[0025] Interfacial co-fusion and improved mechanical properties: Microwaves, with their strong penetrating power, can simultaneously heat the new powder layer and the area near the interface of the solidified solid. This heating method allows for more complete interdiffusion and fusion of materials on both sides of the interface at the molecular level, forming a denser and stronger interface. From a mechanical property perspective, this strong interfacial bonding helps to significantly improve the interlaminar shear strength and tensile properties of the part, reduce anisotropy caused by incomplete interlaminar fusion, and make the part approach the overall density and mechanical property consistency of a monolithic solid. Figure 12 (As shown). Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a microwave heating-based 3D printing system (powder-spreading type) according to the present invention; Figure 2 This is a schematic diagram of the structure of a microwave-heated 3D printing system (powder spraying type) according to the present invention. Figure 3 This is a schematic diagram of the antenna array heating module; Figure 4 This is a schematic diagram of the surface mount unit structure; Figure 5 This is the logic block diagram of the temperature control system; Figure 6 This is a simulation diagram of the antenna array heating module during heating; Figure 7 Simulation and actual measurement of a single element of the antenna array S 11 A curve graph; Figure 8 These are field analysis diagrams of a single element of the antenna array. From left to right, they are the near-field electric field distribution diagram, the near-field magnetic field distribution diagram, and the surface current distribution diagram of the metal patch layer. Figure 9 This is a simulation diagram showing the difference between sprayed and unsprayed absorbing agent; Figure 10 This is a simulation diagram of the antenna array heating module sweeping across the screen after the absorbing agent is sprayed at different positions; Figure 11 This is a schematic diagram illustrating the penetration depth of infrared heating and microwave heating; Figure 12 This is a schematic diagram of the temperature distribution for infrared heating and microwave heating; Reference numerals: 1. Powder recovery system; 2. Antenna array heating module; 3. Spraying assembly; 4. Microwave source; 5. Antenna mounting bracket; 6. Powder spreading module; 7. Powder supply system; 8. 3D printing lifting platform; 9. Powder spraying module; 21. Medium substrate; 22. Surface mount unit; 221. Coaxial feed port; 222. Metal patch layer; 223. Metal grounding layer.

[0028] and spraying components Detailed Implementation To make the technical problems, technical solutions, and technical effects of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0032] Example 1 like Figure 1 , Figures 3 to 11 As shown, this embodiment provides a microwave heating-based 3D printing system, including a 3D printing lifting platform 8, a powder supply and laying system for laying or spraying powder on the 3D printing lifting platform 8, an antenna mounting bracket 5 slidably disposed on the 3D printing lifting platform 8, and an antenna array heating module 2 disposed below the antenna mounting bracket 5. The antenna array heating module 2 includes a dielectric substrate 21, on which at least two rows of patch antenna assemblies are arranged laterally. Each row of patch antenna assemblies includes multiple patch units 22 arranged at intervals. The patch units 22 of adjacent rows of patch antenna assemblies are arranged alternately, and the projection portions of all patch units 22 on the front and rear rows of patch antenna assemblies overlap in the longitudinal direction.

[0033] Each patch unit 22 includes a metal ground layer 223 disposed above the dielectric substrate 21 and a metal patch layer 222 disposed below the dielectric substrate 21 corresponding to the position of the metal ground layer 223. The metal ground layer 223 is provided with a coaxial feed port 221, and each coaxial feed port 221 is connected to a microwave source 4 through a coaxial feed line. The outer conductor of the coaxial feed port 221 is welded to the metal grounding layer 223; The inner conductor of the coaxial feed port 221 passes through the dielectric plate 21 and is soldered onto the metal patch layer 222.

[0034] Two rows of horizontally arranged patch antenna assemblies are provided on the dielectric substrate 21, and each row of patch antenna assemblies includes several patch units 22 arranged horizontally at equal intervals.

[0035] It also includes a temperature control system, which includes a temperature sensor array or infrared imager array for detecting the temperature of the powder to be printed on the 3D printing lifting platform 8, a main control unit, and a data display interface. The temperature sensor array or infrared imager array is connected to the main control unit, and the main control unit is connected to the microwave source 4 and the data display interface.

[0036] The powder supply and laying system includes a powder supply system 7 and a powder recovery system 1 arranged laterally on both sides of the 3D printing lifting platform 8, a powder laying module 6 that lays the powder in the powder supply system 7 onto the 3D printing lifting platform 8 laterally, and a spraying component 3 that is mounted on the antenna mounting bracket 5 and sprays the absorbing agent onto the 3D printing lifting platform 8. The antenna mounting bracket 5 is slidably mounted on the 3D printing lifting platform 8 along the longitudinal direction; The powder supply system 7 includes a powder supply box with an opening at the top. The powder supply box includes a powder supply box side wall and a powder supply box bottom plate that is movably sealed inside the powder supply box side wall. A vertical lifting mechanism is provided at the bottom of the powder supply box bottom plate to drive the powder supply box bottom plate to rise and lower and control the lifting stroke. The powder spreading module 6 includes two transverse guide rails arranged horizontally on both sides of the powder supply box and the 3D printing lifting platform 8, a powder spreading mounting frame set on the two transverse guide rails and reciprocating along the two transverse guide rails, and a powder spreading roller installed longitudinally on the powder spreading mounting frame. The antenna mounting bracket 5 includes a gate-shaped mounting seat that slides longitudinally, two longitudinal mounting plates that are mounted on the gate-shaped mounting seat via a lifting module, a first transverse mounting rod and a second transverse mounting rod connected between the two longitudinal mounting plates, a spraying assembly 3 that slides on the first transverse mounting rod, and an antenna array heating module 2 that is fixedly mounted on the bottom of the second transverse mounting rod.

[0037] The microwave-heated planar powder 3D printing method of this system includes the following steps: S1. The powder supply system 7 raises a layer of powder, and the powder spreading module 6 spreads a layer of powder on the 3D printing lifting platform 8. S2, Spraying component 3 then sprays adhesive or microwave absorber onto the powder on the 3D printing lifting platform 8; S3. Connect the antenna array heating module 2. The antenna array heating module 2 moves longitudinally to the adhesive area that needs to be heated and heats that area. S4. Monitor the local temperature through a temperature sensor array or infrared imager array and feed it back to the main control unit; S5. The main control unit adjusts the activation, power and phase of the antenna array heating module 2 according to the heating requirements to achieve local heating and avoid stress concentration. S6. The antenna array heating module 2 moves longitudinally with the spraying component 3 to achieve dynamic heating along the 3D printing trajectory; S7. Repeat steps S1 to S6, printing layer by layer until the part is complete.

[0038] In step S5, the main control unit uses a PID algorithm to regulate the input power of the antenna array heating module 2: when the temperature is lower than or reaches the target temperature, the input power is kept constant at 150W; when the temperature exceeds the target temperature, the input power is reduced.

[0039] 4. Advantages in interlayer bonding quality: Microwave heating achieves deep fusion, as detailed below: Penetrating heating improves adhesion: In powder bed 3D printing, infrared heating has limited penetration depth, and the heat is mainly concentrated on the surface of the newly laid powder layer. This may result in insufficient temperature at the interface between the new powder layer and the underlying solidified solid to achieve sufficient molecular diffusion and fusion, thus producing relatively weak interlayer adhesion.

[0040] Interfacial co-fusion and enhanced mechanical properties: Microwaves, with their strong penetrating power, can simultaneously heat the new powder layer and the region near the interface of the solidified entity. This heating method allows for more complete interdiffusion and fusion of materials on both sides of the interface at the molecular level, forming a denser and stronger interface. From a mechanical property perspective, this strong interfacial bonding helps to significantly improve the interlaminar shear strength and tensile properties of the part, reduce anisotropy caused by incomplete interlaminar fusion, and make the part approach the consistency of a single-piece solid in terms of overall density and mechanical properties.

[0041] This solution can be used for 3D printing polymer materials.

[0042] Example 2 like Figures 2 to 11 As shown, this embodiment provides a microwave heating-based 3D printing system, including a 3D printing lifting platform 8, a powder supply and laying system for laying or spraying powder on the 3D printing lifting platform 8, an antenna mounting bracket 5 slidably disposed on the 3D printing lifting platform 8, and an antenna array heating module 2 disposed below the antenna mounting bracket 5. The antenna array heating module 2 includes a dielectric substrate 21, on which at least two rows of patch antenna assemblies are arranged laterally. Each row of patch antenna assemblies includes multiple patch units 22 arranged at intervals. The patch units 22 of adjacent rows of patch antenna assemblies are arranged alternately, and the projection portions of all patch units 22 on the front and rear rows of patch antenna assemblies overlap in the longitudinal direction.

[0043] Each patch unit 22 includes a metal ground layer 223 disposed above the dielectric substrate 21 and a metal patch layer 222 disposed below the dielectric substrate 21 corresponding to the position of the metal ground layer 223. The metal ground layer 223 is provided with a coaxial feed port 221, and each coaxial feed port 221 is connected to a microwave source 4 through a coaxial feed line. The outer conductor of the coaxial feed port 221 is welded to the metal grounding layer 223; The inner conductor of the coaxial feed port 221 passes through the dielectric plate 21 and is soldered onto the metal patch layer 222.

[0044] Two rows of horizontally arranged patch antenna assemblies are provided on the dielectric substrate 21, and each row of patch antenna assemblies includes several patch units 22 arranged horizontally at equal intervals.

[0045] It also includes a temperature control system, which includes a temperature sensor array or infrared imager array for detecting the temperature of the powder to be printed on the 3D printing lifting platform 8, a main control unit, and a data display interface. The temperature sensor array or infrared imager array is connected to the main control unit, and the main control unit is connected to the microwave source 4 and the data display interface.

[0046] The antenna mounting frame 5 includes two guide rails arranged longitudinally on both sides of the 3D printing lifting platform 8, a mobile frame arranged above the 3D printing lifting platform 8 and reciprocating along the two guide rails, a first linear drive mechanism for driving the mobile frame to move horizontally, a working mounting frame that can move up and down along the vertical direction of the mobile frame, and a second linear drive mechanism for driving the working mounting frame to move up and down vertically. The powder supply and application system includes a powder spraying module 9 and a spraying assembly 3 mounted on a work mounting frame; Antenna array heating module 2 is mounted on the work mounting frame; The powder spraying module 9, the spraying component 3, and the antenna array heating module 2 are arranged longitudinally on the work mounting frame.

[0047] The system includes a microwave-heated powder spraying 3D printing method, comprising the following steps: S1. The powder spraying module 9 sprays a layer of powder onto the 3D printing lifting platform 8; S2, Spraying component 3 then sprays adhesive or microwave absorber onto the powder on the 3D printing lifting platform 8; S3. Connect the antenna array heating module 2. The antenna array heating module 2 moves longitudinally to the adhesive area that needs to be heated and heats that area. S4. Monitor the local temperature using a temperature sensor or infrared imaging and feed it back to the control system; S5. The control system adjusts the activation, power, and phase of the antenna array heating module 2 according to the heating requirements to achieve local heating and avoid stress concentration. The main control unit's PID algorithm regulates the input power of the antenna array heating module 2: when the temperature is lower than or reaches the target temperature, the input power remains unchanged at 150W; when the temperature exceeds the target temperature, the input power is reduced.

[0048] S6. The antenna array heating module 2 moves longitudinally with the spraying component 3 to achieve dynamic heating along the 3D printing trajectory; S7. Repeat steps S1 to S6, printing layer by layer until the part is complete.

[0049] This solution can be used for 3D printing polymer materials.

[0050] Example 3 Existing additive manufacturing technologies using metal powders have become an important development direction in the industrial manufacturing field. Typical metal 3D printing methods include selective laser melting (SLM), electron beam melting (EBM), and laser metal deposition (LMD). Their forming principles generally rely on the local heating, melting, and solidification of metal powder by a high-energy-density laser beam or particle beam. Taking SLM technology as an example, a high-power laser beam scans the surface of a metal powder bed point by point or line by line, causing the local powder to instantly reach the melting temperature and solidify rapidly, thereby obtaining a dense metal structure. EBM technology uses a high-energy electron beam for heating in a vacuum environment, featuring concentrated heat input and fast forming speed. LMD technology uses synchronous powder feeding and laser melting to form a molten pool, making it suitable for the repair and manufacturing of large-sized metal components. Although metal powder forming technology has been applied in aerospace, mold manufacturing, biomedicine, and other fields, its energy input method is similar to that of polymer powders, and many limitations still exist. First, high-power beams suffer from reflection losses, scattering losses, and insufficient absorption efficiency in metal powder layers, resulting in low energy utilization. Second, the high melting temperature and thermal conductivity of metal materials necessitate maintaining high power density and preheating temperatures to ensure forming quality, leading to persistently high overall system energy consumption. Furthermore, point-by-point scanning methods have limited efficiency in large-scale component forming, and heat accumulation can easily cause residual stress and warping deformation. Therefore, achieving a more efficient, controllable, and low-energy-consumption local heating mechanism in metal powder systems has become a critical bottleneck that metal additive manufacturing technology urgently needs to overcome.

[0051] The microwave-heated 3D printing system disclosed in Example 1 or Example 2 can also be used to print metal powder.

[0052] In Example 1 or Example 2, microwaves, as a volumetric electromagnetic field heating method, differ significantly from the laser or electron beam heating mechanisms commonly used in traditional metal powder 3D printing. In metal powder systems, although metals have high reflectivity, the oxide layer on the particle surface, the dielectric environment formed between particles, and the microwave-absorbing layer that may form on the powder surface can all effectively couple electromagnetic energy to microwaves, allowing energy to be directly deposited into the volumetric region of the powder layer. This overcomes the limitation that lasers can only perform photothermal conversion on the powder surface. Because microwaves can generate dielectric loss within the powder and achieve "inside-out" volumetric heating, the overall temperature rise of the powder is more uniform, and the heat transfer path is significantly shortened. This allows the energy required for powder melting to act more efficiently on the target area, resulting in significantly improved energy utilization compared to SLM, which relies on point-by-point scanning, or EBM, which requires maintaining a vacuum environment.

[0053] In terms of energy consumption, microwave heating features localized selective heating, eliminating the need to maintain a high-temperature environment across the entire powder bed as required by existing metal PBF equipment, and reducing the energy loss associated with maintaining ambient heat. Microwaves can rapidly reach the melting temperature within the target area, with a heating response time in the millisecond range. They possess the ability to simultaneously heat large areas of powder layers, without relying on laser or electron beam point-to-point or line-to-line scanning. Therefore, they offer higher efficiency and greater scalability in the forming of large-size components. The volumetric heating mode of microwaves significantly reduces the temperature gradient between the powder layer and its surface, resulting in a more uniform heat distribution in the molten region. This effectively reduces the risk of thermal stress and warpage during the metal component forming process, and minimizes cracks and incomplete fusion defects caused by rapid cooling, thereby improving the density and microstructure uniformity of the printed metal parts.

[0054] Furthermore, compared to the common problems in laser metal printing such as uneven microstructure and insufficient melting of deep powder layers, microwave energy deposition within metal powder is more conducive to forming a uniform molten pool and a stable solidification process, improving the microstructure consistency and mechanical properties of the formed parts. By adjusting the powder surface coating or introducing a small amount of microwave-absorbing flux, the absorption efficiency of the metal powder to microwaves can be further enhanced, giving microwave-printed metal powder material systems greater design flexibility and applicability to various composite powder systems. Since microwave systems do not require expensive lasers, complex optical components, or high-vacuum cavities, their equipment structure is relatively simple, with lower costs and maintenance difficulty. They also facilitate modular expansion or the construction of large-area array-type energy feed structures, making them suitable for rapid additive manufacturing of large-size metal components.

[0055] In summary, the use of microwaves in metal powder additive manufacturing can not only improve energy utilization efficiency, reduce heat input costs, and improve forming quality, but also break through the limitations of traditional point-by-point scanning mode in terms of speed and size, providing a new, efficient, low-energy-consumption, and scalable heating and forming method for metal additive manufacturing.

Claims

1. A 3D printing system based on microwave heating, characterized in that, The system comprises a 3D printing lifting platform (8), a powder supply and laying system for laying or spraying powder on the 3D printing lifting platform (8), an antenna mounting rack (5) slidingly arranged on the 3D printing lifting platform (8), and an antenna array heating module (2) and a spray assembly (3) for spraying wave absorber arranged below the antenna mounting rack (5); The antenna array heating module (2) comprises a dielectric plate (21) on which at least two rows of transversely arranged patch antenna assemblies are arranged, each row of the patch antenna assemblies comprises a plurality of patch units (22) arranged at intervals, the patch units (22) of the two adjacent rows of the patch antenna assemblies are arranged in a staggered manner, and the projections of all the patch units (22) on the front and rear rows of the patch antenna assemblies in the longitudinal direction partially overlap.

2. The microwave heating based 3D printing system according to claim 1, wherein, Each of the patch units (22) comprises a metal ground layer (223) arranged above the dielectric plate (21), a metal patch layer (222) arranged below the dielectric plate (21) and corresponding to the position of the metal ground layer (223), and a coaxial feed port (221) arranged on the metal ground layer (223), and each of the coaxial feed ports (221) is connected with a microwave source (4) through a coaxial feeder; The outer conductor of the coaxial feed port (221) is welded on the metal ground layer (223); The inner conductor of the coaxial feed port (221) is welded on the metal patch layer (222) through the dielectric plate (21).

3. The microwave heating based 3D printing system according to claim 2, wherein, The dielectric plate (21) is provided with two rows of transversely arranged patch antenna assemblies, and each row of the patch antenna assemblies comprises a plurality of patch units (22) arranged at equal intervals in the transverse direction.

4. The microwave heating based 3D printing system according to claim 2, wherein, It also comprises a temperature main control system, which comprises a temperature sensor array or an infrared imager array for detecting the temperature of the 3D printing powder on the 3D printing lifting platform (8), a main control unit, and a data display interface, the temperature sensor array or the infrared imager array is signal connected with the main control unit, and the main control unit is signal connected with the microwave source (4) and the data display interface.

5. The microwave heating based 3D printing system according to claim 4, wherein, The powder supply and laying system comprises a powder supply system (7) and a powder recycling system (1) arranged on both sides of the 3D printing lifting platform (8) in the transverse direction, a powder laying module (6) for laying the powder in the powder supply system (7) on the 3D printing lifting platform (8) in the transverse direction, and a spray assembly (3) arranged on the antenna mounting rack (5) and spraying wave absorber on the 3D printing lifting platform (8); The antenna mounting rack (5) is slidingly arranged on the 3D printing lifting platform (8) in the longitudinal direction.

6. The 3D printing system based on microwave heating according to claim 5, wherein The powder supply system (7) comprises a powder supply box with an upper opening, the powder supply box comprises a powder supply box side wall and a powder supply box bottom plate movably and sealingly arranged in the powder supply box side wall, and a vertical lifting mechanism is arranged at the bottom of the powder supply box bottom plate to lift the powder supply box bottom plate and control the lifting stroke. The powder laying module (6) comprises two lateral rails arranged laterally on both sides of the powder supply box and the 3D printing lifting platform (8), a powder laying mounting frame reciprocally moving along the two lateral rails, and a powder laying roller mounted longitudinally on the powder laying mounting frame; The antenna mounting frame (5) comprises a door-shaped mounting seat sliding longitudinally, two longitudinal mounting plates arranged on the door-shaped mounting seat by a lifting module, a first lateral mounting rod and a second lateral mounting rod connected between the two longitudinal mounting plates, the spraying assembly (3) slidingly mounted on the first lateral mounting rod, and the antenna array heating module (2) fixedly mounted on the bottom of the second lateral mounting rod.

7. The microwave heating based 3D printing system of claim 4, wherein, The antenna mounting frame (5) comprises two guide rails longitudinally arranged on both sides of the 3D printing lifting platform (8), a moving frame reciprocally moving along the two guide rails arranged above the 3D printing lifting platform (8), a first linear driving mechanism driving the moving frame to horizontally move, a working mounting frame vertically lifting along the moving frame, and a second linear driving mechanism driving the working mounting frame to vertically lift; The powder supply and laying system comprises a powder spraying module (9) and a spraying assembly (3) arranged on the working mounting frame; The antenna array heating module (2) is mounted on the working mounting frame; The powder spraying module (9), the spraying assembly (3), and the antenna array heating module (2) are sequentially arranged longitudinally on the working mounting frame.

8. A tiled powder-based 3D printing method based on microwave heating, using a 3D printing system based on microwave heating according to claim 6, characterized in that, The method comprises the following steps: S1, the powder supply system (7) lifts one layer of powder, and the powder laying module (6) lays one layer of powder on the 3D printing lifting platform (8); S2, the spraying assembly (3) then sprays the binder or the wave-absorbing agent on the powder on the 3D printing lifting platform (8); S3, the antenna array heating module (2) is turned on, and the antenna array heating module (2) moves longitudinally to the binder area needing to be heated to heat the area; S4, the local temperature is monitored by a temperature sensor array or an infrared imager array and fed back to a main control unit; S5, the main control unit adjusts the activation, power, and phase of the antenna array heating module (2) according to the heating requirement, realizes local heating, and avoids stress concentration; S6, the antenna array heating module (2) moves longitudinally with the spraying assembly (3), and realizes dynamic heating along the 3D printing track; S7, steps S1 to S6 are repeated, and the part is printed layer by layer until completed.

9. A microwave heating based tiled powder 3D printing method as claimed in claim 8, wherein, In step S5, the main control unit PID algorithm regulates the input power of the antenna array heating module (2): when the temperature is lower than or reaches the target temperature, the input power of 150 W is kept unchanged, and when the temperature exceeds the target temperature, the input power is reduced.

10. A microwave heating based spray powder type 3D printing method using the microwave heating based 3D printing system of claim 7, characterized in that, The method comprises the following steps: S1, the powder spraying module (9) sprays a layer of powder on the 3D printing lifting platform (8); S2, the spraying assembly (3) then sprays the binder or the wave-absorbing agent on the powder on the 3D printing lifting platform (8); S3, turn on the antenna array heating module (2), the antenna array heating module (2) moves longitudinally to the area that needs to be heated to heat the area; S4, monitor the local temperature through a temperature sensor or infrared imaging and feed back to the control system; S5, the control system adjusts the activation, power and phase of the antenna array heating module (2) according to the heating requirement to realize local heating and avoid stress concentration; S6, the antenna array heating module (2) moves longitudinally with the spraying assembly (3) to realize dynamic heating along the 3D printing track; S7, repeat steps S1 to S6 to print layer by layer until the part is completed.

Images