Method for improving 3D printing quality and device therefor

Abstract

The application belongs to the technical field of additive manufacturing, and discloses a method for improving 3D printing quality and a device thereof, which is used in cooperation with an FDM 3D printing system and comprises a printing platform (4), a cavity (5), a temperature control system, an annular ultrasonic auxiliary system (3), a liquid circulation system and an infrared liquid level detector (8), and the cavity (5) is provided with an ultrasonic generator (53); the annular ultrasonic auxiliary system (3) comprises an annular support (31), an ultrasonic array module (32), a spray head module (33) and a lifting mechanism (34). Through improvement of components, the overall arrangement of the cavity, the temperature control system, the annular ultrasonic auxiliary system, the liquid circulation system and the infrared liquid level detector can effectively improve 3D printing. The device has flexible structure, strong synchronism and excellent local processing capacity, and can significantly improve the surface finish and structural integrity of the FDM 3D printed part.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, and more specifically, relates to a method and apparatus for improving the quality of 3D printing. By introducing ultrasonic assistance during the fused deposition modeling (FDM) printing process, the surface quality can be improved. Background Technology

[0002] With the continuous development of additive manufacturing technology, fused deposition modeling (FDM) technology has been widely used in the printing of polymers and other materials due to its simple process, high flexibility, and applicability to various materials. However, traditional FDM printing processes often suffer from defects such as noticeable steps, roughness, and warping on the surface of printed parts due to problems such as layer-by-layer deposition, uneven cooling, and insufficient material fusion, especially when printing complex structures such as cantilever and groove. In addition, the extrusion of material from the nozzle can easily produce stringing, forming fine filaments or burrs, which degrades the surface quality of the printed parts, affects their appearance and dimensional accuracy, and may reduce their suitability for precision assembly.

[0003] While existing heat treatment or solvent vapor treatment methods can improve surface defects to some extent, they generally suffer from problems such as incomplete or uneven treatment, difficulty in repairing complex structures, and potential structural damage, making it difficult to achieve surface optimization of high-quality printed parts. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a method and apparatus for improving 3D printing quality. By improving the components and utilizing the integrated design of the cavity, temperature control system, annular ultrasonic auxiliary system, liquid circulation system, and infrared liquid level detector, 3D printing quality can be effectively improved. The apparatus of this invention features a flexible structure, strong synchronization, and excellent local processing capabilities, significantly enhancing the surface finish and structural integrity of FDM 3D printed parts.

[0005] To achieve the above objectives, according to one aspect of the present invention, an apparatus for improving the quality of 3D printing is provided for use with an FDM 3D printing system, characterized in that it includes a printing platform (4), a cavity (5), a temperature control system, a ring-shaped ultrasonic auxiliary system (3), a liquid circulation system, and an infrared liquid level detector (8), wherein,

[0006] The printing platform (4) is located inside the cavity (5) and is used to carry the printed sample during the FDM 3D printing process;

[0007] The interior of the cavity (5) is used to hold the treatment solution and is provided with an inlet (51), an outlet (52) and an ultrasonic generator (53). The inlet (51) and the outlet (52) are respectively connected to the liquid circulation system to realize the flow and recycling of the solution. The ultrasonic generator (53) is located at the bottom of the inner wall of the cavity (5) and is used to apply ultrasonic treatment to the entire sample obtained during the FDM 3D printing process.

[0008] The temperature control system includes a heating component (6) and a temperature sensor (54), wherein the temperature sensor (54) is used to sense the temperature of the processing solution in the cavity (5); the heating component (6) can heat the cavity (5) to maintain the temperature of the processing solution;

[0009] The annular ultrasonic auxiliary system (3) includes an annular support (31), an ultrasonic array module (32), a spray head module (33), and a lifting mechanism (34). The lifting mechanism (34) is used to drive the annular support (31) to rise and fall. The ultrasonic array module (32) is located on the lower side of the annular support (31) and is evenly distributed along the annular structure. It is used to perform synchronous ultrasonic treatment on the entire printed layer or a local area of ​​the printed layer during the FDM 3D printing process. The spray head module (33) is installed on the inner ring sidewall of the annular support (31). It is used to perform directional ultrasonic atomization treatment on the entire printed layer or a local area of ​​the printed layer during the FDM 3D printing process to achieve local surface treatment.

[0010] The infrared liquid level detector (8) is installed in the obstacle avoidance area on the top of the device to monitor the liquid level in the cavity in real time. When the real-time liquid level is lower than the target liquid level, the liquid inlet (51) is open to inject liquid into the cavity. When the real-time liquid level reaches the target liquid level, the liquid inlet (51) is closed to stop the injection.

[0011] As a further preferred embodiment of the present invention, the ultrasonic generator (53) is piezoelectric and also supports adjustable frequency control;

[0012] Preferably, the ultrasonic generator (53) has an adjustable operating frequency in the range of 40-80kHz and an ultrasonic power range of 10-80W.

[0013] As a further preferred embodiment of the present invention, the ultrasonic array module (32) in the ring ultrasonic auxiliary system (3) operates at a frequency of 40-50kHz and has an ultrasonic power of 10-20W.

[0014] As a further preferred embodiment of the present invention, the ultrasonic array module (32) includes multiple ultrasonic transducers, an array controller, and multiple drive circuits. The ultrasonic transducers are evenly distributed on the lower side of the annular support (31). Each drive circuit corresponds to one of the ultrasonic transducers. One drive circuit is used to provide input power to one ultrasonic transducer. When any two drive circuits have the same input power, the ultrasonic power output of the corresponding two ultrasonic transducers is also the same. The array controller is used to dynamically adjust the start / stop status, operating frequency, and power output of each transducer by controlling the drive circuits according to the printing process information.

[0015] As a further preferred embodiment of the present invention, the spray head module (33) includes a spray head body, an electric pitch drive mechanism, a rotation adjustment mechanism, and a liquid conduit and a sealing connector connected thereto. The electric pitch drive mechanism is driven by a micro stepper motor or servo motor to control the spray head to adjust the pitch angle in a plane perpendicular to the annular support (31). The rotation adjustment mechanism is used to drive the spray head to adjust the left and right angles in the plane of the annular support (31) to achieve directional adjustment in the horizontal direction.

[0016] As a further preferred embodiment of the present invention, the heating component (6) is a resistance heater and is disposed at the bottom of the cavity (5);

[0017] The temperature sensor (54) is a high-precision temperature sensor with a temperature measurement accuracy of not less than ±0.1℃, and is embedded in the inner wall of the cavity (5).

[0018] As a further preferred embodiment of the present invention, the liquid circulation system includes a circulation pump, a filter, and a storage tank, wherein the storage tank is used to store the treatment solution, and the storage tank is connected to the inlet (51) and the outlet (52) respectively to form a liquid flow path; the filter is disposed between the outlet (52) and the storage tank to remove impurity particles from the liquid; the circulation pump is disposed in the liquid flow path to provide power;

[0019] Preferred,

[0020] The inlet (51) and the outlet (52) are respectively located at the bottom of two opposite sides of the cavity (5);

[0021] The filter is a filter screen or an anti-clogging valve;

[0022] More preferably,

[0023] The storage tank is equipped with a heating auxiliary component for heating the solution in the storage tank and maintaining a constant temperature field. The temperature of the processing solution in the storage tank is stably controlled above the glass transition temperature (Tg) of the printing material and below the thermal oxidation temperature and thermal decomposition temperature of the printing material, preferably 10°C to 20°C above the glass transition temperature (Tg) of the printing material.

[0024] The inlet end of the circulating pump is connected to the outlet end of the storage tank, and the outlet end is connected to the inlet (51) for drawing the solution into the cavity (5).

[0025] The outlet (52) is connected to the inlet end of the storage tank.

[0026] As a further preferred embodiment of the invention, it also includes a computer for temperature control, ring ultrasonic-assisted system lifting control, liquid circulation control, ultrasonic treatment control, and spray head control of the device for improving 3D printing quality, as well as material extrusion control and printing processing control of the FDM 3D printing system.

[0027] As a further preferred embodiment of the present invention, the FDM 3D printing system includes a frame structure, an extruder head, and an extruder head motion module;

[0028] Preferred,

[0029] The annular support (31) is made of a high-temperature resistant material that is corrosion resistant and can withstand temperatures of ≥300℃;

[0030] The cavity (5) is made of a corrosion-resistant and high-temperature resistant material that can withstand temperatures of ≥300℃; the outer surface of the cavity (5) is covered with a heat insulation layer, and the inner wall is precision polished.

[0031] Both the device for improving 3D printing quality and the FDM 3D printing system are located in a constant-temperature environment within a constant-temperature enclosure.

[0032] According to another aspect of the present invention, the present invention provides a method for improving 3D printing quality by using the above-described apparatus for improving 3D printing quality in conjunction with an FDM 3D printing system, characterized by comprising the following steps:

[0033] Step S1: Activate the temperature control device of the storage tank to stably control the temperature of the processing solution above the glass transition temperature (Tg) of the printing material and below the thermal oxidation temperature and thermal decomposition temperature of the printing material.

[0034] Step S2: Calibrate and start the infrared liquid level detector;

[0035] Step S3: Level the printing platform and adjust the extruder height so that the distance between the extruder and the printing platform is one printing layer thickness;

[0036] Step S4: Import the printing model, set the printing parameters, generate the G-code, and transmit it to the FDM 3D printer control system; based on the printing path and height changes, preset a liquid level target curve that dynamically changes with the printing process; wherein, the G-code contains preset key area information;

[0037] Step S5: Inject the processing solution into the cavity so that the initial height of the liquid level is lower than the plane of the printing substrate by one printing layer thickness;

[0038] Step S6: Start the liquid level control system and activate the dynamic closed-loop control of infrared liquid level detection and treatment liquid replenishment;

[0039] Step S7: Start the cavity heating assembly, monitor the solution temperature in real time through the temperature sensor, and ensure that the temperature of the processing liquid in the cavity is maintained above the glass transition temperature (Tg) of the printing material and below the thermal oxidation temperature and thermal decomposition temperature of the printing material; simultaneously turn on the ultrasonic generator (53), set the ultrasonic frequency to 40-50kHz, and set the power to 10-20W.

[0040] Step S8: Initialize the annular ultrasonic array module and the spray head module, and configure the printing layer height recognition and structural feature recognition parameters;

[0041] Step S9: Set the operating frequency of the ultrasonic array module (32) to 40-50kHz and the power to 10-20W, so that the ultrasonic array module (32) enters the standby state;

[0042] Step S10: Start the print job and print the initial layer;

[0043] Step S11: The extruder head rises along the Z-axis by one printing layer thickness, and the control system synchronously adjusts the liquid level to rise to the target height based on the infrared liquid level sensor signal;

[0044] Step S12: Determine whether the current printing area is a key area. If yes, the ring ultrasonic auxiliary system rises synchronously to the specified height, and then automatically triggers the spray head module and ultrasonic array module. The spray head module accurately sprays the treatment liquid at the target area to implement directional ultrasonic treatment. If no, proceed directly to the next step.

[0045] Step S13: Print the current layer; after printing, turn off the spray head module and put the ultrasonic array module (32) into standby mode;

[0046] Step S14: Repeat steps S11 to S13, immersing the entire printed sample in the treatment solution until the entire model is printed;

[0047] Step S15: After printing, keep the printed parts completely immersed in the cavity, adjust the ultrasonic frequency of the ultrasonic generator (53) to 40-80kHz and the power to 30-80W, so that the printed parts are fully ultrasonically treated in the constant temperature treatment solution.

[0048] Step S16: Turn off the ring ultrasonic auxiliary system, ultrasonic generator (53), and cavity heating assembly;

[0049] Step S17: Discharge the treatment solution through the outlet;

[0050] Step S18: Inject deionized water through the inlet to completely immerse the printed sample, restart the ultrasonic generator, and perform ultrasonic cleaning to remove surface residues, micro-defects, and residual treatment liquid using the ultrasonic cavitation effect.

[0051] Step S19: After ultrasonic cleaning is completed, turn off the ultrasonic generator, drain the deionized water, raise the printing platform, and take out the printed sample;

[0052] Step S20: Dry the removed printed sample.

[0053] Compared with existing technologies, the 3D printing quality improvement device of this invention, conceived through the above technical solutions, is used in conjunction with an FDM 3D printing system. Utilizing the integrated design of the cavity, temperature control system, annular ultrasonic auxiliary system, liquid circulation system, and infrared liquid level detector components, it effectively improves 3D printing quality. In particular, this invention utilizes ultrasonic processing to achieve a flexible, highly synchronized, and locally effective ultrasonic-liquid synergistic surface treatment device. This device is used to perform real-time liquid-ultrasonic composite processing in conjunction with the FDM printing process, thereby significantly improving the surface finish and structural integrity of the printed parts. In FDM printing, ultrasound can leverage acoustic cavitation, acoustic flow, and acoustic heat transfer effects to significantly remove surface stringing and micro-defects, improve the mechanical properties of the printed samples, and simultaneously promote the rapid crystallization of printing materials such as polymers, thus enhancing surface finish. When in use, the device of the present invention can maintain the temperature of the processing solution above the glass transition temperature of the printing material to promote the rearrangement of the molecular chains of the printing material and improve the crystallinity. By monitoring the liquid level changes in real time and combining with the control system, dynamic liquid level regulation is achieved. When the liquid level reaches the preset value, the liquid injection is automatically stopped to ensure that the processing liquid continuously covers the forming area during the printing process and avoids over-overflow.

[0054] Current FDM 3D printing technologies generally rely on post-printing processing methods (such as polishing, heat annealing, and solvent vapor treatment). These methods suffer from long processing times, unstable processing accuracy, and poor adaptability to complex structures, severely limiting their effectiveness in improving surface quality. Although ultrasonic-assisted technology has been applied in other material processing fields (such as ultrasonic cleaning), introducing ultrasonic treatment simultaneously during FDM 3D printing can easily affect the stability of the printing process and interlayer adhesion due to the micro-disturbances caused by ultrasound, thus impacting printing accuracy. This is why researchers often avoid simultaneous ultrasonic treatment and instead rely on post-processing. Furthermore, FDM printing relies on thermoplasticization; if the liquid is not controlled, it can easily lead to heat loss, material expansion, or moisture absorption deformation, posing an obstacle to the simultaneous introduction of liquid treatment during printing. Moreover, for cantilevered structures, internal cavities, and complex contours, traditional fixed-point ultrasonic post-processing methods cannot adapt to the layer-by-layer changing three-dimensional paths. To this end, the present invention provides a device for improving 3D printing quality in conjunction with an FDM 3D printing system. This device comprises an ultrasonic generator located on the inner wall of the cavity and an ultrasonic array module whose Z-axis position can be flexibly adjusted. Preferably, the ultrasonic generator's operating frequency is set to 40-80kHz and its power to 10-80W for overall ultrasonic treatment of the printed part. The ultrasonic array module's operating frequency is set to 40-50kHz and its power to 10-20W for directional ultrasonic treatment of the printed layer (or a specific area of ​​the printed layer). This gently adjusts the material's microstructure and repairs surface defects while avoiding mechanical vibration interference during the printing process. Furthermore, the device employs a ring-shaped ultrasonic array and a posture-controllable spray head, overcoming the limitations of single-point treatment and achieving synchronous localized treatment in any direction. Simultaneously, an infrared liquid level detection and feedback system enables dynamic liquid level control during printing, ensuring no interference with the extrusion process. In addition, the device can dynamically adjust the frequency and power of the ultrasonic array according to the height and structural characteristics of the printed layer, achieving energy injection with minimal printing disturbance.

[0055] When using the device of this invention, it can pre-select complex structural areas (such as cantilever, internal cavity, thin wall) or key morphological control areas as key areas according to the actual shape and structure of the sample to be FDM 3D printed, and incorporate the information of the key areas into the G-code, thus:

[0056] (1) During the printing process of complex structures (such as cantilever, groove, inner cavity, thin wall), the system of the present invention can automatically identify key feature areas, accurately spray treatment liquid, and link with the ultrasonic array to apply energy in a directional manner, so as to achieve surface strengthening, defect repair and structural support in specific areas. The ring layout design enables the ultrasonic waves to uniformly surround the printed layer (e.g., the current printed layer) 360°, avoiding ultrasonic energy dead zones and improving processing consistency; at the same time, the attitude-controllable spray head is installed on the inner side wall of the ring support. When a key area (such as a cantilever or groove) is detected, the local spray head is triggered to perform directional ultrasonic atomization treatment. In this way, the treatment of local key structures can be flexibly controlled by the spray head and the ultrasonic array.

[0057] (2) Through infrared liquid level detection and closed-loop control algorithm, the present invention can synchronize liquid level height and printing layer height in real time, maximize the efficiency of sound field action, ensure that the printed parts are always in an ideal liquid phase environment, effectively suppress warping, cracking and internal stress accumulation caused by cooling contraction, and improve the forming quality.

[0058] (3) This invention achieves dynamic flow and purification of the treatment solution through a liquid circulation system, ensuring that the solution remains clean and uniform throughout the printing process. This invention supports multiple solution configuration modes, where each treatment solution is stored in an independent storage tank and transported to the container via independent pipelines; the system is equipped with an automatic switching valve to enable rapid switching between different solutions. For a single solution processing step, the treatment solution can be recycled within the system and returned to the corresponding storage tank, thereby reducing waste and lowering production costs. For cases requiring the synergistic processing of two or more solutions, the mixed solution is not returned to the original storage tank but is collected and processed centrally through an independent mixing channel, avoiding cross-contamination of the original solutions and ensuring stable and reliable solution performance in each storage tank. This invention enables simultaneous printing and surface treatment, eliminating the complex post-processing steps of traditional printing, significantly improving preparation efficiency, and effectively controlling energy consumption and labor costs. Attached Figure Description

[0059] Figure 1 This is a three-dimensional structural diagram of the ultrasonic liquid-assisted surface treatment device of the present invention.

[0060] Figure 2 This is a left-side view of the ultrasonic liquid-assisted surface treatment device of the present invention.

[0061] Figure 3 This is a right-side view of the ultrasonic liquid-assisted surface treatment device of the present invention.

[0062] Figure 4 This is a schematic diagram of the ring ultrasonic-assisted system of the present invention. Figure 4 The C-shaped opening in the image is merely an example; the annular ultrasonic-assisted system is a complete circular ring.

[0063] Figure 5 This is a schematic diagram of the ultrasonic treatment process for FDM printed surfaces.

[0064] Figure 6 These are stereomicroscopic comparison images of samples treated with ultrasound and those not treated with ultrasound, taken at a solution temperature of 153℃ in Example 1. Figure 6 (a) in the text corresponds to the sample that has not undergone ultrasonic treatment. Figure 6 (b) in the text corresponds to the sample that has undergone ultrasonic treatment.

[0065] Figures 1 to 5 The meanings of the reference numerals in the attached figures are as follows:

[0066] 1. Printer frame; 2. Extrusion mechanism; 21. Extrusion head; 22. Extrusion head motion module; 3. Circular ultrasonic auxiliary system; 31. Circular support; 32. Ultrasonic array module; 33. Spray head module; 34. Lifting mechanism; 35. Liquid circulation channel; 4. Printing platform; 5. Cavity; 51. Liquid inlet; 52. Liquid outlet; 53. Ultrasonic generator; 54. Temperature sensor; 6. Heating component; 7. Cavity support; 8. Infrared liquid level detector; 9. Computer. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0068] See Figure 1The ultrasonic liquid-assisted surface treatment device of this invention, used to improve the surface quality of printed parts in an FDM printer, is integrated with an FDM 3D printing system. After integration, it can include a printer frame 1, an extrusion mechanism 2, a ring-shaped ultrasonic auxiliary system 3, a printing platform 4, a cavity 5, a heating assembly 6, a cavity support 7, an infrared liquid level detector 8, and a computer 9. The extrusion mechanism 2 is driven by an extruder head 21 and an extruder head motion module 22. The ring-shaped ultrasonic auxiliary system 3 includes a ring support 31, an ultrasonic array module 32, a spray head module 33, and a lifting mechanism 34 (the ring-shaped ultrasonic auxiliary system 3 is located in the middle of the cavity and outside the printing platform to avoid interfering with the extruder head movement; for example, the inner diameter of the ring-shaped ultrasonic auxiliary system 3 can be larger than the diameter of the smallest circumscribed circle of the printing platform). The spray head module includes a spray head body, an electric pitch drive mechanism, a rotation adjustment mechanism, and connected liquid conduits and sealing connectors. The electric pitch drive mechanism, driven by a micro stepper motor or servo motor, controls the spray head to adjust its pitch angle in the vertical direction. The rotation adjustment mechanism drives the spray head to adjust its angle left and right within the plane of the annular support, achieving horizontal directional adjustment. In addition to temperature control, ring ultrasonic-assisted system lifting control, liquid circulation control, ultrasonic processing control, and spray head control, similar to existing FDM printing systems, computer 9 can also be used for material extrusion control and printing processing control (e.g., movement control of the extruder head in the X, Y, and Z directions) in the FDM 3D printing system.

[0069] The bottom of both sides of the cavity 5 is provided with pipe holes for the inlet and outlet of liquid (specifically, two inlets 51 and one outlet 52 can be designed; the bottom outlet is equipped with a filter screen or anti-clogging valve to prevent large particles from entering the circulation system). Four ultrasonic generators 53 are installed at the bottom of the left and right sides (these two sides are opposite to each other) to ensure the overall surface treatment of the sample, and also include a temperature sensor 54 to detect the temperature of the treatment liquid in the cavity.

[0070] The cavity 5 is used to hold the processing solution, which can be, for example, an etching solution, a polishing solution or an electrical conductivity solution, depending on actual needs, to improve the surface density, surface smoothness and microstructure uniformity of the printed parts, thereby further optimizing the forming quality and performance.

[0071] The printing platform 4 is located inside the cavity 5 and is used to hold the printed sample.

[0072] The heating component 6 can be installed at the bottom of the cavity 5 and controlled in a closed loop by the temperature sensor 54 to keep the solution temperature stable.

[0073] The ultrasonic generator 53 is located on the left and right inner walls of the cavity 5, and uses dual-sided ultrasonic transducers to form a counter-current ultrasonic field, thereby enhancing the effect of the liquid on the surface of the printed part. The operating frequency of the ultrasonic generator 53 is preferably adjustable within the range of 40-80kHz, providing multiple processing modes from rough removal to fine cleaning; the ultrasonic power is set between 10-80W to ensure sufficient cavitation effect. The ultrasonic array module 32 in the annular ultrasonic auxiliary system 3 operates at a frequency of 40-50kHz and has an ultrasonic power of 10-20W.

[0074] The inlet 51 and outlet 52 are respectively located at the bottom of both sides of the cavity 5, so that the liquid forms a horizontal counterflow, ensuring uniform circulation of the solution and timely renewal of the treatment solution; the inlet 51 and outlet 52 are connected to the liquid circulation system to realize dynamic flow and continuous purification of the solution.

[0075] An infrared liquid level detector 8 is located inside the printer frame 1 on the upper left side to detect the liquid level. When the liquid level reaches the set position, the infrared liquid level detector 8 outputs a signal to control the liquid inlet to stop, thus maintaining a stable liquid level.

[0076] Similar to conventional FDM 3D printing, a substrate is mounted on the printing platform. This substrate is made of high-temperature resistant materials, such as ceramics, metal alloys, or high-temperature composite materials, and possesses excellent thermal conductivity. It stably supports the printed sample and also functions as a heat conductor, helping to evenly transfer heat to the bottom of the sample. The cavity is made of high-temperature resistant, corrosion-resistant materials with excellent chemical stability, such as high-temperature ceramics and high-strength stainless steel. An external insulation layer is applied to reduce heat loss; the inner wall is precision polished to reduce impurity adhesion and improve ease of cleaning. Similar to conventional fluid flow devices, all openings are surrounded by high-temperature resistant, corrosion-resistant O-rings or silicone gaskets to ensure a tight seal during liquid circulation and effectively prevent leakage.

[0077] The ultrasonic generator adopts a piezoelectric design and supports adjustable frequency control to adapt to different process requirements.

[0078] The ultrasonic array module 32 includes multiple ultrasonic transducers, an array controller, and multiple drive circuits. The ultrasonic transducers are evenly distributed on the lower side of the annular support 31. The array controller dynamically adjusts the start / stop status, operating frequency, and power output of each transducer by controlling the drive circuits based on printing progress information. Each drive circuit corresponds one-to-one with a ultrasonic transducer; one drive circuit provides input power to one ultrasonic transducer. Furthermore, when any two drive circuits have the same input power, the ultrasonic power output of the corresponding two ultrasonic transducers is also the same. The drive circuits provide stable and adjustable power input to the ultrasonic transducers, ensuring the consistency and reliability of the ultrasonic energy output.

[0079] The combination of heating elements and temperature sensors enables real-time temperature monitoring and control; the adjustable temperature range is from room temperature to 250℃, and temperature fluctuations can be controlled within ±5℃ to ensure that printed samples are processed in an optimal temperature environment. Additionally, the liquid storage tank is equipped with a heating device that continuously heats the solution during circulation, maintaining a constant temperature field and preventing localized temperature fluctuations from affecting print quality.

[0080] The outlet of the cavity is connected to the inlet of the storage tank. After the device is used, the used solution can be filtered and then drawn into the circulation system for further processing to keep the solution clean and stable.

[0081] The entire device can be enclosed inside a temperature-controlled enclosure, ensuring that all components operate stably in a constant temperature environment, reducing interference from the external environment on temperature control, and improving processing consistency and reliability.

[0082] The aforementioned ultrasonic liquid-assisted surface treatment device is used in conjunction with the FDM 3D printing system. The ultrasonic liquid-assisted surface treatment device is installed inside the frame unit; the printing extruder motion module is connected to the top of the printer frame and is driven by a linear motor. The high-speed, high-precision movement of the printing extruder in the X, Y, and Z axes is controlled by a magnetic levitation guide rail.

[0083] To verify the compatibility of the ultrasonic liquid-assisted surface treatment device (especially the ultrasonic generator 53 and ultrasonic array module 32 components) used to improve the surface quality of printed parts in FDM printers with the FDM printing process, we used piezoelectric accelerometers, installed near the printing platform and extruder of the FDM 3D printer, to monitor the vibration response during ultrasonic intervention in real time. Under different ultrasonic frequency (20–80kHz) and power (10–80W) settings, the ultrasonic generator 53 and ultrasonic array module 32 were activated, and printing experiments were conducted. Vibration signals were recorded in real time, and characteristic parameters such as vibration amplitude, frequency, and phase were extracted. Experimental results showed that when the ultrasonic generator operated at a frequency of 40–50kHz and a power of 10–20W, the mechanical vibration disturbance introduced by the system was less than 10% of the vibration intensity of the printing equipment itself, and had almost no substantial impact on printing stability. When the annular ultrasonic array module was intermittently activated at a frequency of 40–60kHz and a power of 10–25W, the mechanical vibration intensity generated was only 6%–8% of the vibration of the system itself. Therefore, the optimal ultrasonic frequency and power range for printing is 40–50kHz and 10–20W. Whether it is a cavity ultrasonic generator or a ring array module, the amplitude of the mechanical vibration disturbance caused is much smaller than the normal operating vibration of the printing equipment itself (the interference amplitude is less than 10%, and some are only 2–5%), and it can ensure that ultrasonic processing is achieved to the maximum extent during printing.

[0084] The device of this invention can perform the following steps during the FDM printing process, thereby achieving real-time surface treatment in the FDM printer and improving the surface quality of the printed parts:

[0085] Step S1: Activate the temperature control device of the storage tank to stabilize the temperature of the treatment solution above the glass transition temperature (Tg) of the printing material and below the thermal oxidation temperature and thermal decomposition temperature of the printing material; in addition to storing the treatment solution in the storage tank, the deionized water used in the subsequent cleaning process is also stored separately in a water storage container (the water temperature can be room temperature).

[0086] In other words, if the minimum value between the thermal oxidation temperature and the thermal decomposition temperature of the printing material is T0, then the processing solution temperature T satisfies Tg < T < T0.

[0087] Step S2: Calibrate and start the infrared liquid level detector;

[0088] Step S3: Level the printing platform 4, adjust the height of the extruder 21 so that the distance between the extruder 21 and the printing platform 4 is one printing layer thickness, and set this position as the initial printing zero point;

[0089] Step S4: Import the printing model, set the printing parameters, generate G-code, and transmit it to the printer control system; based on the printing path and height changes, preset a liquid level target curve that dynamically changes with the printing process;

[0090] Step S5: Inject the processing solution into the cavity 5 so that the initial height of the liquid level is lower than the substrate plane (i.e., the top surface of the substrate) by one printing layer thickness, and set it as the initial liquid level;

[0091] Step S6: Start the liquid level control system and activate the dynamic closed-loop control of infrared liquid level detection 8 and processing liquid replenishment;

[0092] Step S7: Activate the cavity heating assembly 6, and monitor the solution temperature in real time using a temperature sensor to ensure that the temperature of the processing liquid inside the cavity is maintained above the material Tg and below T0, achieving a temperature control accuracy of ±1℃; simultaneously activate the cavity ultrasonic generator 53, and set the operating frequency and power parameters. The ultrasonic frequency of the cavity ultrasonic generator 53 can be set to 40-50kHz, and the power can be set to 10-20W. Since the cavity ultrasonic generator 53 is fixed to the bottom of the cavity, it has strong stability, and the mechanical vibration disturbance it generates is much smaller than the normal vibration amplitude of the FDM 3D printing equipment itself during the printing process.

[0093] Step S8: Initialize the control module of the annular ultrasonic array 32 and the spray head 33, and configure the printing layer height recognition and structural feature recognition parameters;

[0094] Step S9: Set the operating frequency and power parameters of the ultrasonic array module 32 to put the ultrasonic array module 32 into standby mode;

[0095] Step S10: Start the print job and print the initial layer;

[0096] Step S11: The extruder head 21 rises along the Z-axis by one printing layer thickness. The control system synchronously adjusts the liquid level to rise to the target height (i.e., rise by one printing layer thickness) based on the signal from the infrared liquid level sensor 8.

[0097] Step S12: Determine whether the current printing area is a complex structure (such as a cantilever, internal cavity, thin wall, etc.) or a key topography control area. If yes, the local spray head module 33 and ultrasonic array module 32 are automatically triggered. The spray head module 33 accurately sprays the treatment liquid at the target area, and at the same time, the annular ultrasonic auxiliary system 3 rises to the specified height to perform directional ultrasonic treatment. If no, proceed directly to the next step (at this time, the annular ultrasonic auxiliary system hovers or remains stationary).

[0098] Step S13: Print the current layer (that is, when step S12 determines yes, the printing in step S13 is performed when the ultrasonic array module 32 and the spray head module 33 are in working condition; when step S12 determines no, the printing in step S13 is performed when the ultrasonic array module 32 and the spray head module 33 are not in working condition; after the current layer is printed, the work stops regardless of whether the ultrasonic array module 32 and the spray head module 33 are in working condition).

[0099] Step S14: Repeat steps S11 to S13, immersing the entire printed sample in the treatment solution until the entire model is printed;

[0100] Step S15: After printing, keep the printed parts completely immersed and undergo a round of full ultrasonic fine polishing in a constant temperature treatment solution. At this time, the ultrasonic frequency of the cavity ultrasonic generator 53 can be set to 40-80kHz and the power can be set to 30-80W.

[0101] Step S16: Turn off the ring ultrasonic auxiliary system 3, ultrasonic generator 53 and heating component 6;

[0102] Step S17: Discharge the treatment solution through outlet 52;

[0103] Step S18: Inject deionized water through inlet 51 to completely immerse the printed sample, restart the ultrasonic generator 53, and perform ultrasonic cleaning (e.g., 30 minutes) to remove surface residues, micro-defects and residual treatment liquid using the ultrasonic cavitation effect.

[0104] Step S19: After ultrasonic cleaning is completed, turn off the ultrasonic generator 53, discharge the deionized water through the outlet 52 (different from the treatment solution, the deionized water used for cleaning is not recycled), raise the printing platform 4, and take out the printed sample.

[0105] Step S20: Place the removed printed sample in a vacuum drying oven for drying.

[0106] Example 1: Surface Brushing Treatment for PEEK Material Printing

[0107] The ultrasonic liquid-assisted surface treatment device provided by this invention is suitable for surface drawing and particle removal of polymer printed parts during FDM molding. During printing, the liquid level is dynamically monitored by an infrared detector and rises synchronously with the printed layer, gradually submerging the printed part with the treatment solution to ensure continuous and precise processing. The ultrasonic transducer generates cavitation in the solution, effectively removing surface defects, particles, and drawing marks, improving the smoothness and precision of the printed part. The liquid circulation system maintains solution flow and cleanliness, ensuring the stability and consistency of the surface treatment process. After printing, the printed part continues to undergo comprehensive ultrasonic fine treatment in the solution, further optimizing the surface morphology and microstructure. Finally, the printed part is removed and dried or subjected to subsequent processing. The specific implementation process, combining the above steps, is as follows:

[0108] Step S1: Place the PEEK filament in a vacuum oven at 120°C and dry for 10 hours;

[0109] Step S2: Prepare the liquid. In this example, a mixed solution of deionized water and N,N-dimethylformamide (DMF) is used as the treatment liquid. Combining the high purity of deionized water with the good solubility of polar solvents, impurities generated during the printing process are effectively removed under high temperature conditions, and the surface quality and crystallization properties of PEEK prints are optimized.

[0110] Step S3: Turn on the temperature control device of the storage tank to heat the solution to 153°C;

[0111] Step S4: Calibrate and start the infrared liquid level detector 8;

[0112] Step S5: Adjust the printing platform 4 to be horizontal, adjust the height of the extruder 21 so that the distance between it and the printing platform 4 is 0.2mm, and set this position as the initial printing position;

[0113] Step S6: Inject a high-temperature solution into the cavity 5 so that the liquid level is 0.2mm lower than the plane of the printing platform 4. Turn on the circulation pump so that the solution flows laterally through the inlet 51 and the outlet 52 to prevent particle deposition during printing, keep the solution clean, and remove suspended impurities through the filtration system.

[0114] Step S7: Start the heating component 6, and use the temperature sensor 54 to detect the solution temperature to maintain the solution temperature in the cavity 5 at about 153°C.

[0115] Step S8`: Start the ultrasonic generator 53, set the operating frequency to 40kHz, and the power to 20W. The ultrasonic generator 53 started in this step is mainly used for synchronous ultrasonic treatment during the printing process. By acting on the printing layer in real time, it promotes material crystallization, improves surface smoothness and structural integrity, and at the same time, it works with temperature control to ensure that the material is in a suitable state. Other frequencies in the low-to-mid frequency range of 40–50kHz and other powers in the range of 10–20W can also be used in this step to gently remove surface impurities and stringing, while adjusting the microstructure of the material and repairing surface defects, and avoiding mechanical vibration interference to the printing process.

[0116] Step S9: Import the printing model, set the nozzle temperature to 400℃, the printing speed to 30mm / s, the layer thickness to 0.2mm, generate G-code and liquid surface target change data, and transmit them to the computer control software;

[0117] Step S10: Initialize the control module of the annular ultrasonic array 32 and the spray head 33, and configure the printing layer height recognition and structural feature recognition parameters;

[0118] Step S11: Set the operating frequency and power parameters of the ultrasonic array module 32 to 40kHz and 20W respectively, so that the ultrasonic array module 32 enters the standby state.

[0119] Step S12: Start the print job and print the initial layer;

[0120] Step S13: The extruder head 21 rises 0.2mm along the Z-axis, and the control system synchronously adjusts the liquid level to rise to the target height based on the signal from the infrared liquid level sensor 8;

[0121] Step S14: Determine whether the current printing area is a complex structure or a key morphology control area. If yes, automatically trigger the local spray head module 33 and the ultrasonic array module 32. The spray head module 33 accurately sprays the treatment liquid at the target area, and at the same time, the ring ultrasonic auxiliary system 3 rises to the specified height to implement directional ultrasonic treatment. If no, proceed directly to the next step.

[0122] Step S15: Print the current layer;

[0123] Step S16: Repeat steps S13 to S15, immersing the entire printed sample in the treatment solution until the entire model is printed;

[0124] Step S17: After printing, keep the printed part completely immersed in a constant-temperature treatment solution for 2 hours for comprehensive ultrasonic fine treatment. During this time, the ultrasonic frequency of the cavity ultrasonic generator 53 is set to 60kHz, and the power can be set to 50W to promote full crystallization of the PEEK material. This ultrasonic treatment step involves a comprehensive and fine ultrasonic treatment of the entire printed part after printing. The main purpose is to deeply clean the surface residues and micro-defects of the printed part, further improving surface quality and mechanical properties. This step can also use a wider frequency range (40–80kHz) and higher power (30–80W) to enhance the ultrasonic cavitation effect and acoustic flow effect, achieving thorough cleaning and strengthening of the surface and internal micropores of the printed part.

[0125] Step S18: Turn off the ring ultrasonic auxiliary system 3, ultrasonic generator 53 and heating component 6. After the solution cools naturally to room temperature, discharge the solution through the outlet 52.

[0126] Step S19: Pass deionized water into the liquid inlet 51 to completely immerse the printed sample, restart the ultrasonic generator 53, and perform ultrasonic cleaning for 30 minutes to remove surface residues, micro-defects and residual solution using the ultrasonic cavitation effect.

[0127] Step S20: Turn off the ultrasonic generator 53, extract the deionized water through the liquid outlet 52, raise the printing platform 4, take out the printed sample, and place the printed sample in a vacuum drying oven at 120℃ for 24 hours.

[0128] Through the above steps, surface treatment was performed using a mixed solution of deionized water and N,N-dimethylformamide (DMF). The surface stringing phenomenon of the treated PEEK samples was significantly reduced compared to the untreated samples (the untreated samples were prepared under the same printing parameters, solution type, and temperature, but without activating the ultrasonic generator 53 and the ultrasonic array module 32). The surface smoothness was significantly improved, such as... Figure 6 As shown.

[0129] In addition to the 153℃ treatment solution temperature used in Example 1, we also investigated the effect of different treatment solution temperatures on the results. PEEK material was again selected as the research object. The Tg of PEEK material is 133℃. The treatment solution temperature was set to a range of 20℃ below Tg and 30℃ above Tg, i.e., [133℃-20℃, 133℃+30℃]. Specific temperature points included 113℃, 123℃, 133℃, 143℃, 153℃, and 163℃. Comparative experiments were conducted with and without an ultrasonic field (with an ultrasonic field means applying ultrasound according to the frequency and power conditions of the ultrasonic generator 53 and ultrasonic array module 32 described in Example 1; without an ultrasonic field means neither the ultrasonic generator 53 nor the ultrasonic array module 32 was activated). Surface roughness (Ra) was measured using a laser confocal microscope. The results are as follows:

[0130] 113 4.12 3.90 5.3％ 123 3.95 2.85 27.8％ 133 3.74 2.05 45.2％ 143 3.60 1.91 46.9％ 153 3.57 2.03 43.2％ 163 3.62 2.35 35.1％

[0131] Further analysis using differential scanning calorimetry (DSC) was performed to determine the change in crystallinity.

[0132] 113 19.2 20.4 +6.3％ 123 22.7 27.1 +19.4％ 133 25.0 32.4 +29.6％ 143 26.8 34.3 +27.9％ 153 27.3 33.2 +21.6％ 163 28.8 34.3 +19.1％

[0133] Based on stereomicroscopic observations, under treatment solution temperatures of [Tg+10℃, Tg+20℃], ultrasonic treatment significantly reduced surface stringing and hanging debris, resulting in a denser surface, enhanced interfacial fusion, and marked mitigation of interlayer delamination defects. Therefore, the optimal temperature range for the treatment solution is [Tg+10℃, Tg+20℃] to ensure the synergistic effect of the treatment solution and ultrasound, thereby improving FDM printing quality and guaranteeing excellent processing results.

[0134] Example 2: Printing and Polishing Process of PLA Material

[0135] The ultrasonic-liquid synergistic surface treatment device provided by this invention can perform efficient surface polishing on polymer printed parts during FDM printing, effectively improving the smoothness and precision of the printed parts. During printing, an infrared detector dynamically monitors the liquid level, ensuring that the liquid level rises synchronously with the printed layer, allowing the printed part to be gradually immersed in the heated polishing liquid. The ultrasonic transducer generates a cavitation effect to remove surface defects, and the liquid circulation system maintains solution flow and cleanliness. After printing, the printed part undergoes final ultrasonic treatment in the polishing liquid to further optimize the surface smoothness, and is finally removed for drying or post-processing. Based on the above general steps, the specific embodiment steps are as follows:

[0136] Step S1: Place the PLA filament in a vacuum oven at 60°C and dry for 2 hours;

[0137] Step S2: Prepare the liquid. In this example, a polishing solution made by mixing deionized water with an appropriate amount of polishing agent is used as a low-temperature cleaning solution. This mixed solution utilizes the high purity of deionized water and the surface polishing effect of the polishing agent to effectively remove tiny particles and surface defects generated during the printing process at a lower temperature, while improving the surface finish and interlayer bonding strength of PLA prints.

[0138] Step S3: Turn on the temperature control device of the storage tank to heat the solution to 60°C;

[0139] Step S4: Calibrate and start the infrared liquid level detector 8;

[0140] Step S5: Adjust the printing platform 4 to be horizontal, adjust the height of the extruder 21 so that the distance between it and the printing platform 4 is 0.1mm, and set this position as the initial printing position;

[0141] Step S6: Inject the treatment solution into the cavity 5 so that the liquid level is 0.1mm lower than the plane of the printing platform 4. Turn on the circulation pump so that the solution forms a horizontal counterflow through the inlet 51 and outlet 52 to prevent particle deposition during printing, keep the solution clean, and remove suspended impurities through the filtration system.

[0142] Step S7: Start the heating component 6, and use the temperature sensor 54 to detect the solution temperature to maintain the solution temperature in the cavity 5 at about 60°C.

[0143] Step S8: Start the ultrasonic generator 53, set the operating frequency to 40kHz, and the power to 15W;

[0144] Step S9: Import the printing model, set the nozzle temperature to 210℃, the printing speed to 30mm / s, the layer thickness to 0.1mm, generate G-code and liquid surface target change data, and transmit them to the computer control software;

[0145] Step S10: Initialize the control module of the annular ultrasonic array 32 and the spray head 33, and configure the printing layer height recognition and structural feature recognition parameters;

[0146] Step S11: Set the operating frequency and power parameters of the ultrasonic array module 32 to 40kHz and 10W respectively, so that the ultrasonic array module 32 enters the standby state.

[0147] Step S12: Start the print job and print the initial layer;

[0148] Step S13: The extruder head 21 rises 0.1mm along the Z-axis, and the control system synchronously adjusts the liquid level to rise to the target height based on the signal from the infrared liquid level sensor 8.

[0149] Step S14: Determine whether the current printing area is a complex structure or a key morphology control area. If yes, automatically trigger the local spray head module 33 and the ultrasonic array module 32. The spray head module 33 accurately sprays the treatment liquid at the target area, while the annular ultrasonic auxiliary system 3 rises to the specified height to perform directional ultrasonic treatment. If no, proceed directly to the next step.

[0150] Step S15: Print the current layer;

[0151] Step S16: Repeat steps S13 to S15, immersing the entire printed sample in the treatment solution until the entire model is printed;

[0152] Step S17: After printing, keep the printed parts completely immersed, set the ultrasonic generator 53 to 50kHz and the power to 30W, and allow it to undergo full ultrasonic fine polishing treatment in a constant temperature treatment solution for 2 hours.

[0153] Step S18: Turn off the ring ultrasonic auxiliary system 3, ultrasonic generator 53 and heating component 6. After the solution cools naturally to room temperature, discharge the solution through the outlet 52.

[0154] Step S19: Pass deionized water into the liquid inlet 51 to completely immerse the printed sample, restart the ultrasonic generator 53, and perform ultrasonic cleaning for 30 minutes to remove surface residues, micro-defects and residual solution using the ultrasonic cavitation effect.

[0155] Step S20: Turn off the ultrasonic generator 53, extract the deionized water through the liquid outlet 52, raise the printing platform 4, take out the printed sample, and place the printed sample in a 60℃ vacuum drying oven to dry for 24 hours.

[0156] Through the above steps, the surface roughness (Ra value) of the PLA print decreased from about 3.2 μm without ultrasonic treatment to 1.1 μm (the untreated sample was prepared under the same printing parameters, solution type, and temperature, but without starting the ultrasonic generator 53 and the ultrasonic array module 32), and the dimensional accuracy of the print improved by about 15%.

[0157] Example 3: Surface Repair Treatment for Nylon Material Printing

[0158] The ultrasonic liquid-assisted surface treatment device provided by this invention can efficiently repair the surface of polymer printed parts during FDM printing. Taking the surface repair of nylon materials as an example, this invention constructs an electro-acoustic composite surface repair behavior by combining an electrically conductive solution with ultrasonic technology, achieving local self-repair, thereby significantly improving the surface finish and precision of the printed parts. Specific implementation steps are as follows:

[0159] Step S1: Place the nylon filament in a vacuum oven at 80°C and dry for 6 hours;

[0160] Step S2: Prepare the liquid. In this example, a conductive solution containing silver nanoparticles is selected as the surface repair treatment solution. This mixed solution utilizes the good conductivity of silver nanoparticles to effectively promote the realization of the electro-acoustic composite repair mechanism, thereby improving the surface repair effect.

[0161] Step S3: Turn on the temperature control device of the storage tank to heat the solution to 80°C;

[0162] Step S4: Calibrate and start the infrared liquid level detector 8;

[0163] Step S5: Adjust the printing platform 4 to be horizontal, adjust the height of the extruder 21 so that the distance between it and the printing platform 4 is 0.3mm, and set this position as the initial printing position;

[0164] Step S6: Inject the treatment solution into the cavity 5 so that the liquid level is 0.3mm lower than the plane of the printing platform 4. Turn on the circulation pump so that the solution forms a horizontal counterflow through the inlet 51 and outlet 52 to prevent particle deposition during printing, keep the solution clean, and remove suspended impurities through the filtration system.

[0165] Step S7: Start the heating component 6, and use the temperature sensor 54 to detect the solution temperature to maintain the solution temperature in the cavity 5 at about 80°C.

[0166] Step S8: Start the ultrasonic generator 53, set the operating frequency to 45kHz, and the power to 20W;

[0167] Step S9: Import the printing model, set the nozzle temperature to 260℃, the printing speed to 30mm / s, the layer thickness to 0.3mm, generate G-code and liquid surface target change data, and transmit them to the computer control software.

[0168] Step S10: Initialize the control module of the annular ultrasonic array 32 and the spray head 33, and configure the printing layer height recognition and structural feature recognition parameters;

[0169] Step S11: Set the operating frequency and power parameters of the ultrasonic array module 32 to 40kHz and 15W respectively, so that the ultrasonic array module 32 enters the standby state.

[0170] Step S12: Start the print job and print the initial layer;

[0171] Step S13: The extruder head 21 rises 0.3mm along the Z-axis, and the control system synchronously adjusts the liquid level to rise to the target height based on the signal from the infrared liquid level sensor 8.

[0172] Step S14: Determine whether the current printing area is a complex structure or a key morphology control area. If yes, automatically trigger the local spray head module 33 and the ultrasonic array module 32. The spray head module 33 accurately sprays the treatment liquid at the target area, while the annular ultrasonic auxiliary system 3 rises to the specified height to perform directional ultrasonic treatment. If no, proceed directly to the next step.

[0173] Step S15: Print the current layer;

[0174] Step S16: Repeat steps S13 to S15, immersing the printed sample entirely in the treatment solution until the entire model is printed;

[0175] Step S17: After printing, keep the printed parts completely immersed, set the ultrasonic generator 53 to 60kHz and the power to 50W, and allow it to undergo full ultrasonic fine surface repair treatment in a constant temperature treatment solution for 2 hours.

[0176] Step S18: Turn off the ring ultrasonic auxiliary system 3, ultrasonic generator 53 and heating component 6. After the solution cools naturally to room temperature, discharge the solution through the outlet 52.

[0177] Step S19: Introduce deionized water into the liquid inlet 51 to completely immerse the printed sample, restart the ultrasonic generator 53, and perform ultrasonic cleaning for 30 minutes to remove surface residues, micro-defects and residual solution using the ultrasonic cavitation effect.

[0178] Step S20: Turn off the ultrasonic generator 53, extract the deionized water through the liquid outlet 52, raise the printing platform 4, take out the printed sample, and place the printed sample in an 80℃ vacuum drying oven to dry for 24 hours.

[0179] Through the above steps, the surface contact angle of the nylon printed part was reduced from 95° to 25° without ultrasonic treatment (the untreated sample was prepared under the same printing parameters, solution type, and temperature, but without starting the ultrasonic generator 53 and the ultrasonic array module 32), and the repair depth reached 10μm.

[0180] The above embodiments are merely examples. For instance, in addition to melt extrusion molding of polymer materials, the apparatus of the present invention is also applicable to other material systems that employ melt extrusion molding processes, such as metal-polymer composites, fusible metal wires, thermoplastic elastomers, etc., and has good material adaptability and process compatibility.

[0181] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for improving 3D printing quality, used in conjunction with an FDM 3D printing system, characterized in that, It includes a printing platform (4), a cavity (5), a temperature control system, a ring ultrasonic auxiliary system (3), a liquid circulation system, and an infrared liquid level detector (8), among which, The printing platform (4) is located inside the cavity (5) and is used to carry the printed sample during the FDM 3D printing process; The interior of the cavity (5) is used to hold the processing solution and is provided with an inlet (51), an outlet (52) and an ultrasonic generator (53). The inlet (51) and the outlet (52) are respectively connected to the liquid circulation system to realize the flow and recycling of the solution. The ultrasonic generator (53) is located at the bottom of the inner wall of the cavity (5) and is used to apply ultrasonic treatment to the entire sample obtained during the FDM3D printing process. The temperature control system includes a heating component (6) and a temperature sensor (54), wherein the temperature sensor (54) is used to sense the temperature of the processing solution in the cavity (5); the heating component (6) can heat the cavity (5) to maintain the temperature of the processing solution; The annular ultrasonic auxiliary system (3) includes an annular support (31), an ultrasonic array module (32), a spray head module (33), and a lifting mechanism (34). The lifting mechanism (34) is used to drive the annular support (31) to rise and fall. The ultrasonic array module (32) is located on the lower side of the annular support (31) and is evenly distributed along the annular structure. It is used to perform synchronous ultrasonic treatment on the entire printed layer or a local area of ​​the printed layer during the FDM 3D printing process. The spray head module (33) is installed on the inner ring sidewall of the annular support (31). It is used to perform directional ultrasonic atomization treatment on the entire printed layer or a local area of ​​the printed layer during the FDM 3D printing process to achieve local surface treatment. The infrared liquid level detector (8) is installed in the obstacle avoidance area on the top of the device to monitor the liquid level in the cavity in real time. When the real-time liquid level is lower than the target liquid level, the liquid inlet (51) is open to inject liquid into the cavity. When the real-time liquid level reaches the target liquid level, the liquid inlet (51) is closed to stop the injection.

2. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, The ultrasonic generator (53) is piezoelectric and also supports adjustable frequency control.

3. The apparatus for improving 3D printing quality as described in claim 2, characterized in that, The ultrasonic generator (53) has an adjustable operating frequency in the range of 40-80 kHz and an ultrasonic power range of 10-80 W.

4. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, The ultrasonic array module (32) in the ring ultrasonic auxiliary system (3) operates at a frequency of 40-50 kHz and has an ultrasonic power of 10-20 W.

5. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, The ultrasonic array module (32) includes multiple ultrasonic transducers, an array controller, and multiple drive circuits. The ultrasonic transducers are evenly distributed on the underside of the annular support (31). Each drive circuit corresponds to one of the ultrasonic transducers. One drive circuit is used to provide input power to one ultrasonic transducer. When any two drive circuits have the same input power, the ultrasonic power output of the corresponding two ultrasonic transducers is also the same. The array controller is used to dynamically adjust the start / stop status, operating frequency, and power output of each transducer by controlling the drive circuits according to the printing process information.

6. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, The spray head module (33) includes a spray head body, an electric pitch drive mechanism, a rotation adjustment mechanism, and a liquid conduit and sealing connector connected thereto. The electric pitch drive mechanism is driven by a micro stepper motor or servo motor to control the spray head to adjust the pitch angle in a plane perpendicular to the annular support (31). The rotation adjustment mechanism is used to drive the spray head to adjust the left and right angles in the plane of the annular support (31) to achieve horizontal directional adjustment.

7. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, The heating component (6) is a resistance heater and is located at the bottom of the cavity (5); The temperature sensor (54) is a high-precision temperature sensor with a temperature measurement accuracy of not less than ±0.1℃, and is embedded in the inner wall of the cavity (5).

8. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, The liquid circulation system includes a circulation pump, a filter, and a storage tank. The storage tank is used to store the treatment solution and is connected to the inlet (51) and the outlet (52) to form a liquid flow path. The filter is located between the outlet (52) and the storage tank to remove impurity particles from the liquid. The circulation pump is located on the liquid flow path to provide power.

9. The apparatus for improving 3D printing quality as described in claim 8, characterized in that, The inlet (51) and the outlet (52) are respectively located at the bottom of two opposite sides of the cavity (5); The filter is a filter screen or an anti-clogging valve.

10. The apparatus for improving 3D printing quality as described in claim 8, characterized in that, The storage tank is equipped with a heating auxiliary component for heating the solution in the storage tank and maintaining a constant temperature field; the temperature of the processing solution in the storage tank is stably controlled above the glass transition temperature (Tg) of the printing material and below the thermal oxidation temperature and thermal decomposition temperature of the printing material. The inlet end of the circulating pump is connected to the outlet end of the storage tank, and the outlet end is connected to the inlet (51) for drawing the solution into the cavity (5). The outlet (52) is connected to the inlet end of the storage tank.

11. The apparatus for improving 3D printing quality as described in claim 10, characterized in that, The temperature of the treatment solution in the storage tank is stably controlled at 10°C to 20°C above the glass transition temperature (Tg) of the printing material, and below the thermal oxidation temperature and thermal decomposition temperature of the printing material.

12. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, It also includes a computer for temperature control, ring ultrasonic-assisted system lifting control, liquid circulation control, ultrasonic processing control and spray head control of the device for improving 3D printing quality, as well as material extrusion control and printing processing control of the FDM 3D printing system.

13. The apparatus for improving 3D printing quality as described in claim 1, characterized in that, The FDM 3D printing system includes a frame structure, an extruder head, and an extruder head motion module.

14. The apparatus for improving 3D printing quality as described in claim 13, characterized in that, The annular support (31) is made of a corrosion-resistant, high-temperature resistant material that can withstand temperatures of ≥300 ℃; The cavity (5) is made of a corrosion-resistant and high-temperature resistant material that can withstand temperatures of ≥300 ℃; the outer surface of the cavity (5) is covered with a heat insulation layer, and the inner wall is precision polished. Both the device for improving 3D printing quality and the FDM 3D printing system are located in a constant-temperature environment within a constant-temperature enclosure.

15. A method for improving 3D printing quality by using the apparatus for improving 3D printing quality as described in claim 10 or 11 in conjunction with an FDM 3D printing system, characterized in that, Includes the following steps: Step S1: Activate the heating auxiliary component equipped with the storage tank to stably control the temperature of the processing solution above the glass transition temperature (Tg) of the printing material and below the thermal oxidation temperature and thermal decomposition temperature of the printing material; Step S2: Calibrate and start the infrared liquid level detector; Step S3: Level the printing platform and adjust the extruder height so that the distance between the extruder and the printing platform is one printing layer thickness; Step S4: Import the printing model, set the printing parameters, generate the G-code, and transmit it to the FDM 3D printer control system; Based on the printing path and height changes, a preset target curve for the liquid level is dynamically changed as the printing process progresses; wherein, the G-code contains preset local region information; Step S5: Inject the processing solution into the cavity so that the initial height of the liquid level is lower than the plane of the printing substrate by one printing layer thickness; Step S6: Start the liquid circulation system and activate the dynamic closed-loop control of infrared liquid level detection and processing liquid replenishment; Step S7: Start the heating component and monitor the solution temperature in real time through the temperature sensor to ensure that the temperature of the processing liquid in the cavity is maintained above the glass transition temperature (Tg) of the printing material and below the thermal oxidation temperature and thermal decomposition temperature of the printing material; simultaneously turn on the ultrasonic generator (53), set the ultrasonic frequency to 40-50kHz, and set the power to 10-20W. Step S8: Initialize the annular ultrasonic array module and the spray head module, and configure the printing layer height recognition and structural feature recognition parameters; Step S9: Set the operating frequency of the ultrasonic array module (32) to 40-50 kHz and the power to 10-20 W, so that the ultrasonic array module (32) enters the standby state; Step S10: Start the print job and print the initial layer; Step S11: The extruder head rises along the Z-axis by one printing layer thickness, and the control system synchronously adjusts the liquid level to rise to the target height based on the infrared liquid level detector signal; Step S12: Determine whether the current printing area is a local area. If yes, the ring ultrasonic auxiliary system rises synchronously to the specified height, and then automatically triggers the spray head module and ultrasonic array module. The spray head module accurately sprays the treatment liquid at the target area to implement directional ultrasonic treatment. If no, proceed directly to the next step. Step S13: Print the current layer; After printing is complete, turn off the spray head module and put the ultrasonic array module (32) into standby mode; Step S14: Repeat steps S11 to S13, immersing the entire printed sample in the treatment solution until the entire model is printed; Step S15: After printing, keep the printed parts completely immersed in the cavity, adjust the ultrasonic frequency of the ultrasonic generator (53) to 40-80 kHz and the power to 30-80 W, so that the printed parts are fully ultrasonically treated in the constant temperature treatment solution. Step S16: Turn off the ring ultrasonic auxiliary system, ultrasonic generator (53), and heating assembly; Step S17: Discharge the treatment solution through the outlet; Step S18: Inject deionized water through the inlet to completely immerse the printed sample, restart the ultrasonic generator, and perform ultrasonic cleaning to remove surface residues, micro-defects, and residual treatment liquid using the ultrasonic cavitation effect. Step S19: After ultrasonic cleaning is completed, turn off the ultrasonic generator, drain the deionized water, raise the printing platform, and take out the printed sample; Step S20: Dry the removed printed sample.

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