Method and device for improving 3D printing quality

Abstract

The invention belongs to the technical field of additive manufacturing, and discloses a method and device for improving 3D printing quality, the device is used for being matched with an FDM 3D printing system, the device comprises a printing platform (4), a containing 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 containing 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 header module (33) and a lifting mechanism (34). According to the 3D printing device, the assemblies are improved, and 3D printing can be effectively improved through the overall arrangement of the containing cavity, the temperature control system, the annular ultrasonic auxiliary system, the liquid circulation system and the infrared liquid level detector. The device is flexible in structure, high in synchronism and excellent in local treatment capacity, and the surface smoothness and structural integrity of the FDM 3D printing piece can be remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of additive manufacturing technology, and more specifically, relates to a method and device for improving 3D printing quality, which can improve surface quality by introducing ultrasonic assistance during the fused deposition modeling (FDM) printing process. Background Art

[0002] With the continuous development of additive manufacturing technology, fused deposition modeling (FDM) technology has been widely used in the printing of materials such as polymers due to its simple process, high flexibility, and applicability to a variety of materials. However, due to problems such as layer-by-layer stacking, uneven cooling, and insufficient material welding, the traditional FDM printing process often results in defects such as obvious steps, roughness, and warping on the surface of the printed parts. This is particularly prominent when printing complex structures such as cantilevers and grooves. In addition, when the nozzle extrudes the material, it is easy to produce wire drawing, forming filaments or burrs, which reduces the surface quality of the printed part, affects its appearance and dimensional accuracy, and may reduce its adaptability in precision assembly.

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

[0004] To address the aforementioned deficiencies and improvements in the prior art, the present invention aims to provide a method and apparatus for improving 3D printing quality. By improving the overall configuration of the chamber, temperature control system, annular ultrasonic auxiliary system, liquid circulation system, and infrared liquid level detector, the present invention effectively enhances 3D printing quality. The apparatus boasts a flexible structure, strong synchronization, and excellent local processing capabilities, significantly improving the surface finish and structural integrity of FDM 3D printed parts.

[0005] To achieve the above-mentioned object, according to one aspect of the present invention, a device for improving 3D printing quality is provided, which is used in conjunction with an FDM 3D printing system, and is 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), wherein:

[0006] The printing platform (4) is located in 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 a treatment solution and is provided with a liquid inlet (51), a liquid outlet (52) and an ultrasonic generator (53), wherein the liquid inlet (51) and the liquid outlet (52) are respectively connected to the liquid circulation system to achieve the flow and recycling of the solution; the ultrasonic generator (53) is arranged at the bottom of the inner wall of the cavity (5) and is used to apply ultrasonic treatment to the entire sample obtained in the FDM 3D printing process;

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

[0009] 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), wherein the lifting mechanism (34) is used to drive the annular support (31) to move up and down; the ultrasonic array module (32) is arranged on the lower side of the annular support (31) and is evenly distributed along the annular structure, and 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 side wall of the annular support (31), and 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 and is used 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 opened 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 injecting liquid.

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

[0012] Preferably, the operating frequency of the ultrasonic generator (53) is adjustable within the range of 40-80 kHz, and the ultrasonic power range is set between 10-80 W.

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

[0014] As a further preferred embodiment of the present invention, the ultrasonic array module (32) includes a plurality of ultrasonic transducers, an array controller and a plurality of drive circuits, wherein the ultrasonic transducers are evenly distributed on the lower side of the annular bracket (31); the drive circuits correspond to the ultrasonic transducers one by one, and one drive circuit is used to provide input power to one ultrasonic transducer, and when the input power of any two drive circuits is the same, the ultrasonic power outputs of the corresponding two ultrasonic transducers are also the same; the array controller is used to dynamically adjust the start and stop state, operating frequency and power output of each transducer by controlling the drive circuit according to 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, wherein the electric pitch drive mechanism is driven by a micro stepping motor or a servo to control the spray head to adjust the pitch angle in a direction perpendicular to the plane where the annular bracket (31) is located; the rotation adjustment mechanism is used to drive the spray head to adjust the left and right angles within the plane where the annular bracket (31) is located, thereby realizing directional adjustment in the horizontal direction.

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

[0017] The temperature sensor (54) is a high-precision temperature sensor with a temperature measurement accuracy not inferior to ±0.1°C and is embedded on 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 liquid storage tank, wherein the liquid storage tank is used to store the treatment solution, and the liquid storage tank is respectively connected to the liquid inlet (51) and the liquid outlet (52) to form a liquid flow path; the filter is arranged between the liquid outlet (52) and the liquid storage tank, and is used to remove foreign particles in the liquid; the circulation pump is arranged in the liquid flow path, and is used to provide power;

[0019] Preferably,

[0020] The liquid inlet (51) and the liquid outlet (52) are respectively arranged 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 liquid storage tank is equipped with a heating auxiliary component for heating the solution in the liquid storage tank to maintain a constant temperature field; the temperature of the processing solution in the liquid storage tank is stably controlled to be 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 circulation pump is connected to the outlet of the liquid storage tank, and the outlet end is connected to the liquid inlet (51), for drawing the solution into the cavity (5);

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

[0026] As a further preferred embodiment of the present invention, a computer is further included for temperature control of the device for improving 3D printing quality, lifting control of the annular ultrasonic auxiliary system, liquid circulation control, ultrasonic processing control and sprinkler head control, 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 extrusion head and an extrusion head motion module;

[0028] Preferably,

[0029] The annular bracket (31) is made of a corrosion-resistant and high-temperature resistant material capable of withstanding temperatures of ≥300°C;

[0030] The cavity (5) is made of a corrosion-resistant and high-temperature resistant material capable of withstanding temperatures of ≥300°C; the exterior of the cavity (5) is covered with a heat-insulating layer, and the interior wall is precisely polished;

[0031] The device for improving 3D printing quality and the FDM 3D printing system are both located in a constant temperature environment of the constant temperature housing.

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

[0033] Step S1: Start the temperature control device of the liquid storage tank to stably control the temperature of the processing solution to be 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 height of the extruder head so that the distance between the extruder head and the printing platform is one printing layer thickness;

[0036] Step S4: Importing the printing model, setting printing parameters, generating G-code, and transmitting it to the FDM 3D printer control system; presetting a liquid level target curve that changes dynamically with the printing process based on the printing path and height changes; wherein the G-code includes preset key area information;

[0037] Step S5: injecting a treatment solution into the chamber so that the initial height of the liquid level is lower than the plane of the printing substrate by a thickness of a printing layer;

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

[0039] Step S7: Start the cavity 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; synchronously start the ultrasonic generator (53), set the ultrasonic action frequency to 40-50kHz, and set the power to 10-20W;

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

[0041] Step S9: setting 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 a standby state;

[0042] Step S10: Start the printing 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 controls the liquid level to rise to the target height according to the signal from the infrared liquid level sensor;

[0044] Step S12: Determine whether the current printing area is a key area. If so, the annular ultrasonic auxiliary system rises to a specified height, and then automatically triggers the spray head module and the ultrasonic array module. The spray head module precisely aligns with the target area to spray the treatment liquid and implement directional ultrasonic treatment. If not, proceed directly to the next step.

[0045] Step S13: Print the current layer; after printing is completed, close the spray head module and put the ultrasonic array module (32) into a standby state;

[0046] Step S14: cyclically executing steps S11 to S13, the entire printed sample is immersed in the treatment liquid until the entire model is printed;

[0047] Step S15: After printing is completed, the printed piece is kept in a completely immersed state in the cavity, and the ultrasonic action frequency of the ultrasonic generator (53) is adjusted to 40-80kHz and the power to 30-80W, so that the printed piece as a whole is fully ultrasonically treated in the constant temperature treatment solution;

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

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

[0050] Step S18: Deionized water is injected through the liquid inlet to completely immerse the printed sample, and the ultrasonic generator is restarted to perform ultrasonic cleaning to remove surface residues, micro defects and residual processing liquid using the ultrasonic cavitation effect;

[0051] Step S19: After ultrasonic cleaning is completed, the ultrasonic generator is turned off, the deionized water is drained, the printing platform is raised, and the printed sample is taken out;

[0052] Step S20: Drying the taken-out printed sample.

[0053] Through the above technical solutions conceived by the present invention, compared with the existing technology, the device for improving the quality of 3D printing in the present invention is used to cooperate with the FDM 3D printing system, and utilizes the overall setting of the components of the device, such as the cavity, temperature control system, annular ultrasonic auxiliary system, liquid circulation system and infrared liquid level detector, to effectively improve 3D printing. The device for improving the quality of 3D printing in the present invention particularly utilizes ultrasonic treatment to obtain an ultrasonic liquid collaborative surface treatment device with flexible structure, strong synchronization and excellent local processing ability, which is used to perform liquid ultrasonic composite treatment in real time in conjunction with the FDM printing process, thereby significantly improving the surface finish and structural integrity of the printed part. In FDM printing, ultrasonic waves can exert acoustic cavitation effect, acoustic streaming effect and acoustic wave heat transfer effect, which can significantly remove surface brushing and micro defects, improve the mechanical properties of printed samples, and promote the rapid crystallization of printing materials such as polymers to improve surface finish. When in use, the device of the present invention can maintain the temperature of the processing solution higher than the glass transition temperature of the printing material to promote the rearrangement of the molecular chains of the printing material and the improvement of the crystallinity; by real-time monitoring of liquid level changes and combining with a control system, dynamic liquid level regulation is achieved. When the liquid level reaches a preset value, the injection is automatically stopped to ensure that the processing liquid continues to cover the molding area during the printing process and avoid overflow.

[0054] Existing FDM 3D printing technology generally relies on post-printing processing (such as polishing, heating annealing, solvent vapor treatment, etc.). These methods have problems such as long processing time, unstable processing accuracy, and poor adaptability to complex structures, and are very limited in improving surface quality. Although ultrasonic-assisted technology has been applied in other material processing fields (such as ultrasonic cleaning, etc.), if ultrasonic treatment is introduced simultaneously during the FDM 3D printing process, the micro-disturbance caused by ultrasonic waves can easily affect the stability of the printing process and the interlayer adhesion effect, affecting the printing accuracy. This is why researchers often do not use synchronous ultrasonic treatment, but mostly use post-processing. At the same time, FDM printing relies on hot melt plasticization. If the liquid is not controlled, it is very easy to cause heat loss or material expansion and moisture absorption deformation, which also brings obstacles to the simultaneous introduction of liquid treatment during the printing process. In addition, for cantilevers, inner cavities, complex contours, etc., traditional fixed-point ultrasonic post-processing methods cannot adapt to the three-dimensional paths that change layer by layer. To this end, the present invention has designed a device for cooperating with an FDM 3D printing system to improve 3D printing quality. The device comprises an ultrasonic generator located on the inner wall of a cavity and an ultrasonic array module capable of flexibly adjusting its Z-direction position. The ultrasonic generator's operating frequency is preferably set to 40-80kHz and its power to 10-80W, enabling 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, enabling targeted ultrasonic treatment of the printed layer (or specific areas of the printed layer). This allows for gentle adjustment of the material's microstructure and repair of surface defects while avoiding mechanical vibration interference with the printing process. Furthermore, the device utilizes a circular ultrasonic array and a gesture-controlled spray head, breaking through the limitations of single-point treatment and enabling simultaneous localized treatment in any direction. Furthermore, an infrared liquid level detection and feedback system enables dynamic liquid level control during printing, ensuring no interference with the extrusion process. Furthermore, the device dynamically adjusts the frequency and power of the ultrasonic array based on the height and structural characteristics of the printed layer, achieving energy injection with minimal disturbance to the print.

[0055] When the device of the present invention is used, complex structure areas (such as cantilevers, inner cavities, thin walls) or key morphology control areas can be pre-selected as key areas according to the actual shape and structure of the sample to be FDM 3D printed, and the key area information can be included in the G-code code, as follows:

[0056] (1) During the printing process of complex structures (such as cantilevers, grooves, inner cavities, and thin walls), the system of the present invention can automatically identify key feature areas, accurately spray treatment liquid, and link the ultrasonic array to apply energy in a directional manner to achieve surface strengthening, defect repair, and structural support in specific areas. The annular layout design enables ultrasonic waves to achieve 360° uniform encirclement of the printed layer (such as the current printed layer), avoiding ultrasonic energy blind spots and improving processing consistency; at the same time, the attitude-controllable spray head is installed on the inner side wall of the annular bracket. When a key area (such as a key structure such as a cantilever or groove) is detected, the local spray head is triggered to implement directional ultrasonic atomization treatment, so that the treatment of local key structures can be achieved through flexible control of the spray head and ultrasonic array;

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

[0058] (3) The present invention realizes the dynamic flow and purification of the treatment solution through a liquid circulation system, ensuring that the solution always remains clean and uniform during the printing process. The present invention supports a variety of solution configuration modes, in which each treatment solution is stored in an independent liquid storage tank and transported to the cavity through an independent pipeline; the system is provided with an automatic switching valve to realize rapid switching of different solutions. For a single solution treatment process, the treatment solution can be circulated in the system and returned to the corresponding liquid storage tank, thereby reducing waste and lowering production costs. For situations where two or more solutions need to be mixed and treated in a coordinated manner, the mixed solution no longer flows back to the original liquid storage tank, but is collected and processed centrally through an independent mixing treatment channel to avoid cross-contamination of the original solution and ensure that the performance of the solution in each liquid storage tank is stable and reliable. The present invention realizes the simultaneous printing and surface treatment, omitting the complicated post-processing steps after traditional printing, significantly improving preparation efficiency, and effectively controlling energy consumption and labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic diagram of the three-dimensional structure of the ultrasonic liquid coordinated surface treatment device of the present invention.

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

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

[0062] Figure 4 This is a schematic structural diagram of the annular ultrasonic auxiliary system of the present invention. Figure 4 The C-shaped opening is only an example, and the annular ultrasonic auxiliary system is a complete circular ring.

[0063] Figure 5 Schematic diagram of the ultrasonic treatment process for FDM printing surfaces.

[0064] Figure 6 This is a stereomicroscope comparison of the sample after ultrasonic treatment and the sample without ultrasonic treatment when the treatment solution temperature is 153°C in Example 1; Figure 6 (a) corresponds to the sample without ultrasonic treatment. Figure 6 (b) in the figure corresponds to the sample after ultrasonic treatment.

[0065] Figures 1 to 5 In the figure, the meanings of the reference numerals are as follows:

[0066] 1. Printer frame; 2. Extrusion mechanism; 21. Extrusion head; 22. Extrusion head motion module; 3. Annular ultrasonic auxiliary system; 31. Annular bracket; 32. Ultrasonic array module; 33. Sprinkler 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 bracket; 8. Infrared liquid level detector; 9. Computer. DETAILED DESCRIPTION

[0067] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is 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 for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0068] See also Figure 1The ultrasonic-liquid synergistic surface treatment device for improving the surface quality of printed parts in an FDM printer, as disclosed herein, is used in conjunction with an FDM 3D printing system. After integration with the FDM 3D printing system, the device may include a printer frame 1, an extruder mechanism 2, an annular ultrasonic auxiliary system 3, a printing platform 4, a chamber 5, a heating assembly 6, a chamber support 7, an infrared liquid level detector 8, and a computer 9. The extruder mechanism 2 is driven by an extruder head 21 and an extruder head motion module 22. 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 annular ultrasonic auxiliary system 3 is located in the middle of the chamber and outside the printing platform to avoid interfering with the extruder head's movement; for example, the inner diameter of the annular ultrasonic auxiliary system 3 may be larger than the diameter of the minimum circumscribed circle of the printing platform.) The showerhead module includes a showerhead body, an electric pitch drive mechanism, a rotary adjustment mechanism, and connected liquid conduits and sealing connectors. The electric pitch drive mechanism, driven by a micro-stepping motor or servo, controls the showerhead's vertical pitch angle adjustment. The rotary adjustment mechanism drives the showerhead's left and right angle adjustment within the plane of the annular bracket, achieving horizontal directional adjustment. In addition to controlling temperature, controlling the elevation of the annular ultrasonic-assisted system, controlling liquid circulation, controlling ultrasonic processing, and controlling the showerhead, computer 9 can also be used for material extrusion control and printing process control (e.g., controlling the extruder's motion in the X, Y, and Z directions) in the FDM 3D printing system, similar to existing FDM printing.

[0069] Pipe holes are provided at the bottom of both sides of the cavity 5, which are used for the inflow and outflow of liquid respectively (specifically, two liquid inlets 51 and one liquid outlet 52 can be designed; the bottom outlet is equipped with a filter screen or an 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. A temperature sensor 54 is also included to detect the temperature of the treatment liquid in the cavity.

[0070] The cavity 5 is used to hold a processing solution, which can be, for example, a corrosive solution, a polishing solution, or a conductive solution according to actual needs, to improve the surface density, surface smoothness, and microstructure uniformity of the printed part, thereby further optimizing the forming quality and performance.

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

[0072] The heating assembly 6 can be installed at the bottom of the cavity 5 and perform closed-loop control through 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 chamber 5. It uses dual-sided ultrasonic transducers to form opposing ultrasonic fields, thereby enhancing the effect of the liquid on the printed surface. The operating frequency of the ultrasonic generator 53 is preferably adjustable within the range of 40-80 kHz, providing a variety of treatment modes from rough removal to fine cleaning. The ultrasonic power range is set between 10-80 W to ensure sufficient cavitation. The ultrasonic array module 32 in the annular ultrasonic auxiliary system 3 operates at a frequency of 40-50 kHz and an ultrasonic power of 10-20 W.

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

[0075] The infrared liquid level detector 8 is arranged on the upper left side of the printer frame 1 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 to stop and maintain the liquid level stable.

[0076] In addition, similar to conventional FDM 3D printing, a base plate is installed on the printing platform. The base plate is made of high-temperature resistant materials, such as ceramics, metal alloys or high-temperature resistant composite materials. It has good thermal conductivity and is used to stably support the printed sample. At the same time, it also has a heat conduction function, which helps to evenly transfer heat to the bottom of the sample. The cavity is made of high-temperature resistant, corrosion-resistant and chemically stable materials, such as high-temperature resistant ceramics and high-strength stainless steel; the outside is covered with an insulation layer to reduce heat loss; the inner wall is precisely polished to reduce impurity adhesion and improve cleaning convenience. Similar to conventional liquid flow devices, all openings are surrounded by high-temperature and corrosion-resistant O-rings or silicone gaskets to ensure airtightness during liquid circulation and effectively prevent leakage.

[0077] The ultrasonic generator adopts 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 underside 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 to each ultrasonic transducer, with each drive circuit providing input power to each ultrasonic transducer. When the power inputs to any two drive circuits are the same, the ultrasonic power outputs of the two corresponding ultrasonic transducers are also the same. The drive circuit provides stable and adjustable power input to the ultrasonic transducers, ensuring consistent and reliable ultrasonic energy output.

[0079] The combination of a heating assembly and a temperature sensor enables real-time temperature monitoring and control. The temperature can be adjusted from room temperature to 250°C, with temperature fluctuations controlled within ±5°C to ensure that printed samples are processed in an optimal temperature environment. Furthermore, the liquid reservoir is equipped with a heating device that continuously heats the solution during circulation, maintaining a constant temperature field and preventing local temperature fluctuations from affecting print quality.

[0080] The liquid outlet of the cavity is connected to the inlet of the liquid storage tank. After the device is used, the used solution can be filtered and extracted into the circulation system for reprocessing to keep the solution clean and stable in performance.

[0081] In particular, the entire device can be enclosed inside a constant temperature housing to ensure that all components operate stably in a constant temperature environment, reduce interference from the external environment on temperature control, and improve processing consistency and reliability.

[0082] The above-mentioned ultrasonic liquid collaborative surface treatment device is used to cooperate with the FDM 3D printing system. The ultrasonic liquid collaborative surface treatment device is installed in the rack unit; the print extruder motion module is connected to the top of the printer rack and is driven by a linear motor. The high-speed and high-precision movement of the print extruder in the X-axis, Y-axis and Z-axis directions is controlled by a magnetic levitation guide rail.

[0083] To verify the compatibility of the ultrasonic-liquid synergistic surface treatment device (particularly the ultrasonic generator 53 and ultrasonic array module 32) for improving the surface quality of printed parts in FDM printers with the FDM printing process, we employed piezoelectric accelerometers, mounted on the print platform and near the extruder head of an FDM 3D printer, to monitor the vibration response during ultrasonic intervention in real time. Printing experiments were conducted using the ultrasonic generator 53 and ultrasonic array module 32 at various ultrasonic frequency (20–80 kHz) and power (10–80 W). The vibration signals were recorded in real time, and characteristic parameters such as amplitude, frequency, and phase were extracted. The experimental results showed that when the ultrasonic generator was operated at a frequency of 40–50 kHz and a power of 10–20 W, the mechanical vibration disturbance introduced by the system was less than 10% of the vibration intensity of the printing device itself, with virtually no significant impact on printing stability. When the annular ultrasonic array module was intermittently activated at a frequency of 40–60 kHz and a power of 10–25 W, the mechanical vibration intensity generated was only 6–8% of the system's inherent vibration intensity. Therefore, the optimal ultrasonic frequency and power range for printing is: 40–50 kHz and 10–20 W. Whether it is the cavity ultrasonic generator or the annular array module, the amplitude of the mechanical vibration disturbance caused is much smaller than the normal operating vibration of the printing device itself (the interference amplitude is less than 10%, and some are only 2–5%), and can ensure that ultrasonic processing is obtained to the greatest extent during printing.

[0084] During the FDM printing process, the device of the present invention can be carried out according to the following steps to achieve real-time surface treatment in the FDM printer and improve the surface quality of the printed part:

[0085] Step S1: Start the temperature control device of the liquid 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; in addition to storing the processing solution in the liquid 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 at room temperature).

[0086] That is, let T0 be the minimum value of the thermal oxidation temperature and the thermal decomposition temperature of the printing material, 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 and adjust the height of the extruder head 21 so that the distance between the extruder head 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 the liquid level target curve that changes dynamically with the printing process;

[0090] Step S5: injecting the processing solution into the chamber 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 setting it as the initial liquid level;

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

[0092] Step S7: Start the cavity heating assembly 6 and monitor the solution temperature in real time via a temperature sensor to ensure that the temperature of the processing liquid in the cavity is maintained above the material Tg and below T0, with a temperature control accuracy of ±1°C. Simultaneously, start 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. Because 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 far smaller than the normal vibration amplitude of the FDM 3D printing equipment itself during the printing process.

[0093] Step S8: Initializing the annular ultrasonic array 32 and the spray head 33 control module, and configuring the printing layer height recognition and structure feature recognition parameters;

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

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

[0096] Step S11: the extruder head 21 rises along the Z axis by one printing layer thickness, and the control system synchronously controls the liquid level to rise to the target height (i.e., by one printing layer thickness) according to 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, inner cavity, thin wall, etc.) or a key morphology control area. If so, the local spray head module 33 and the ultrasonic array module 32 are automatically triggered. The spray head module 33 precisely aims at the target area and sprays the treatment liquid. At the same time, the annular ultrasonic auxiliary system 3 rises to a specified height to perform directional ultrasonic treatment. If not, proceed directly to the next step (at this time, the annular ultrasonic auxiliary system is hovering or remains stationary).

[0098] Step S13: Printing the current layer (that is, when the judgment of step S12 is yes, the printing in step S13 is performed while the ultrasonic array module 32 and the shower head module 33 are in the working state; when the judgment of step S12 is no, the printing in step S13 is performed while the ultrasonic array module 32 and the shower head module 33 are not in the working state; after the printing of the current layer is completed, the ultrasonic array module 32 and the shower head module 33 stop working regardless of whether they are in the working state).

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

[0100] Step S15: After printing is completed, the printed part is kept completely immersed and subjected to a round of comprehensive ultrasonic fine polishing treatment 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 annular ultrasonic auxiliary system 3, the ultrasonic generator 53 and the heating component 6;

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

[0103] Step S18: Deionized water is injected through the liquid inlet 51 to completely immerse the printed sample, and the ultrasonic generator 53 is restarted to perform ultrasonic cleaning (e.g., for 30 minutes) to remove surface residues, micro-defects, and residual processing liquid using the ultrasonic cavitation effect;

[0104] Step S19: After ultrasonic cleaning is completed, the ultrasonic generator 53 is turned off, the deionized water is discharged through the liquid outlet 52 (unlike the treatment solution, the deionized water used for cleaning is not recycled), the printing platform 4 is raised, and the printed sample is taken out;

[0105] Step S20: placing the taken-out printed sample in a vacuum drying oven for drying.

[0106] Example 1: PEEK material printing surface brushing treatment

[0107] The ultrasonic liquid collaborative surface treatment device provided by the present invention is suitable for surface brushing treatment and particle removal of polymer prints during the FDM forming process. During the printing process, the liquid level is dynamically monitored by an infrared detector and rises synchronously with the printing layer. The treatment solution gradually submerges the print to ensure that the treatment process is continuous and precise. The ultrasonic transducer produces a cavitation effect in the solution, effectively removing surface defects, particles and brushing marks, and improving the smoothness and precision of the print. The liquid circulation system keeps the solution flowing and clean, ensuring the stability and consistency of the surface treatment process. After printing is completed, the print continues to receive comprehensive ultrasonic fine treatment in the solution to further optimize the surface morphology and microstructure. Finally, the print is taken out and dried or subsequently processed. In combination with the above steps, the specific implementation process is as follows:

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

[0109] Step S2: Prepare the liquid. This example uses a mixture of deionized water and N,N-dimethylformamide (DMF) as the processing liquid. Combining the high purity of deionized water with the good solubility of polar solvents, it effectively removes impurities generated during the printing process under high temperature conditions and optimizes the surface quality and crystallization properties of PEEK prints.

[0110] Step S3': Turn on the temperature control device of the liquid storage tank and 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 a horizontal position, adjust the height of the extruder head 21 so that the distance between the extruder head 21 and the printing platform 4 is 0.2 mm, and set this position as the initial printing position;

[0113] Step S6': injecting high-temperature solution into the chamber 5 so that the liquid level is 0.2 mm below the plane of the printing platform 4, and starting the circulation pump to allow the solution to form a horizontal counterflow through the liquid inlet 51 and the liquid 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 detect the solution temperature through the temperature sensor 54 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 set the power to 20W. The ultrasonic generator 53 activated in this step is mainly used for synchronous ultrasonic treatment during the printing process. By acting on the printed layer in real time, it promotes material crystallization, improves surface finish and structural integrity, and cooperates with temperature control to ensure that the material is in a suitable state. This step can also use other frequencies in the medium and low frequency range of 40-50kHz and other powers in the range of 10-20W to gently remove surface impurities and wire drawing, while adjusting the material microstructure and repairing surface defects, and avoiding mechanical vibration interference with the printing process.

[0116] Step S9': import the printing model, set the nozzle temperature to 400°C, the printing speed to 30 mm / s, the layer thickness to 0.2 mm, generate G-code code and liquid level target change data, and transmit them to the computer 9 control software;

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

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

[0119] Step S12': start the printing job and print the initial layer;

[0120] Step S13': the extrusion head 21 rises 0.2 mm along the Z axis, and the control system synchronously controls the liquid level to rise to the target height according to 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 so, the local spray head module 33 and the ultrasonic array module 32 are automatically triggered. The spray head module 33 precisely aligns with the target area to spray the treatment liquid. At the same time, the annular ultrasonic auxiliary system 3 rises to a specified height to perform directional ultrasonic treatment. If not, proceed directly to the next step.

[0122] Step S15`: Print the current layer;

[0123] Step S16': looping through steps S13' to S15', immersing the entire printed sample in the treatment liquid until the entire model is printed;

[0124] Step S17`: After printing is completed, the printed part is kept completely immersed and subjected to comprehensive ultrasonic fine treatment in a constant temperature treatment solution for 2 hours. At 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 the full crystallization of the PEEK material. The ultrasonic treatment in this step is to perform comprehensive fine ultrasonic treatment on the entire printed part after printing is completed. The main purpose is to deeply clean the surface residues and micro-defects of the printed part, further improving the 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 streaming effect, achieving thorough cleaning and strengthening of the printed part surface and internal micropores.

[0125] Step S18': Turn off the annular ultrasonic auxiliary system 3, the ultrasonic generator 53 and the heating assembly 6, and after the solution is naturally cooled to room temperature, discharge the solution through the liquid outlet 52;

[0126] Step S19': Deionized water is introduced into the liquid inlet 51 to completely immerse the printed sample, and the ultrasonic generator 53 is restarted to perform ultrasonic cleaning for 30 minutes to remove surface residues, micro defects and residual solution by 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°C for 24 hours.

[0128] Through the above steps, the surface treatment is performed using a mixed solution of deionized water and N,N-dimethylformamide (DMF). The surface wire drawing phenomenon of the treated PEEK sample is significantly reduced compared with the sample without ultrasonic treatment (the sample without ultrasonic treatment is 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 surface smoothness is significantly improved. Figure 6 shown.

[0129] In addition to the 153°C treatment solution temperature used in Example 1, we also studied the effects of different treatment solution temperatures on the results. PEEK material was also selected as the research object. The Tg of PEEK material is 133°C. The treatment solution temperature was set within the range of 20°C below the material Tg to 30°C above the Tg, that is, [133°C-20°C, 133°C+30°C]. Specific temperature points included 113°C, 123°C, 133°C, 143°C, 153°C, and 163°C. Comparative tests were conducted with and without an ultrasonic field (with an ultrasonic field, ultrasound was applied 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, ultrasound was not activated, and neither the ultrasonic generator 53 nor the ultrasonic array module 32 was activated). Surface roughness (Ra) was measured using a laser confocal microscope, and the results are as follows:

[0130] Temperature (℃) Without ultrasonic treatment Ra (μm) Ultrasonic treatment Ra (μm) Reduction rate (%) 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] The crystallinity change was further determined by differential scanning calorimetry (DSC):

[0132] Temperature (℃) Crystallinity without ultrasound (%) Ultrasonic treatment crystallinity (%) Increase (%) 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] Combined with stereomicroscope observations, at treatment solution temperatures between [Tg + 10°C and Tg + 20°C], ultrasonic treatment significantly reduced surface stringing and overhanging, resulting in a denser surface, significantly enhanced interfacial fusion, and significantly alleviated interlayer delamination defects. Therefore, it is recommended to control the treatment solution temperature between [Tg + 10°C and Tg + 20°C] to ensure a synergistic effect between the treatment solution and ultrasound, improve FDM printing quality, and ensure optimal treatment results.

[0134] Example 2: PLA material printing and polishing

[0135] The ultrasonic liquid collaborative surface treatment device provided by the present invention can perform efficient surface polishing treatment on polymer prints during the FDM printing process, effectively improving the smoothness and precision of the prints. During the printing process, the infrared detector dynamically monitors the liquid level to ensure that the liquid level rises synchronously with the printed layer, so that the print is gradually immersed in the heated polishing liquid. The ultrasonic transducer produces a cavitation effect to remove surface defects, and the liquid circulation system maintains the flow and cleanliness of the solution. After printing is completed, the print undergoes a final ultrasonic treatment in the polishing liquid to further optimize the surface finish, and is finally taken out and dried or post-processed. Combined with the description of the above general steps, the specific embodiment steps are as follows:

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

[0137] Step S2: Prepare the liquid. This example uses a polishing solution made by mixing deionized water with an appropriate amount of polishing agent as the 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 low temperatures, while also improving the surface finish and interlayer bonding strength of PLA prints.

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

[0139] Step S4: calibrating and starting the infrared liquid level detector 8;

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

[0141] Step S6: Inject the treatment solution into the chamber 5 so that the liquid level is 0.1 mm below the plane of the printing platform 4. Start the circulation pump to allow the solution to flow horizontally through the liquid inlet 51 and the liquid 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 detect the solution temperature through the temperature sensor 54 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°C, the printing speed to 30 mm / s, and the layer thickness to 0.1 mm, generate G-code and liquid level target change data, and transmit them to the computer 9 control software;

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

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

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

[0148] Step S13: The extrusion head 21 rises 0.1 mm along the Z axis, and the control system synchronously controls the liquid level to rise to the target height according to 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 so, the local spray head module 33 and the ultrasonic array module 32 are automatically triggered. The spray head module 33 precisely aligns with the target area to spray the treatment liquid. At the same time, the annular ultrasonic auxiliary system 3 rises to the specified height to perform directional ultrasonic treatment. If not, proceed directly to the next step.

[0150] Step S15: Print the current layer;

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

[0152] Step S17: After printing is completed, the printed part is kept in a completely immersed state, the operating frequency of the ultrasonic generator 53 is set to 50 kHz, the power is set to 30 W, and the printed part is subjected to a comprehensive ultrasonic fine polishing treatment in a constant temperature treatment solution for 2 hours;

[0153] Step S18: Turn off the annular ultrasonic auxiliary system 3, the ultrasonic generator 53 and the heating assembly 6, and after the solution is naturally cooled to room temperature, discharge the solution through the liquid outlet 52;

[0154] Step S19: Deionized water is introduced into the liquid inlet 51 to completely immerse the printed sample, and the ultrasonic generator 53 is restarted to perform ultrasonic cleaning for 30 minutes to remove surface residues, micro-defects and residual solution by 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 vacuum drying oven at 60°C for 24 hours.

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

[0157] Example 3: Surface repair of nylon printing materials

[0158] The ultrasonic-liquid synergistic surface treatment device provided by the present invention can efficiently repair the surface of polymer printed parts during the FDM printing process. Taking the surface repair of nylon materials as an example, the present invention combines a conductive solution with ultrasonic technology to create an electro-acoustic composite surface repair behavior, achieving localized self-repair, thereby significantly improving the surface finish and precision of the printed parts. The specific embodiment steps are as follows:

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

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

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

[0162] Step S4: calibrating and starting the infrared liquid level detector 8;

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

[0164] Step S6: Inject the treatment solution into the chamber 5 so that the liquid level is 0.3 mm below the plane of the printing platform 4. Start the circulation pump to allow the solution to flow horizontally through the liquid inlet 51 and the liquid 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 assembly 6 and detect the solution temperature through the temperature sensor 54 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°C, the printing speed to 30 mm / s, and the layer thickness to 0.3 mm, generate G-code and liquid level target change data, and transmit them to the computer 9 control software;

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

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

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

[0171] Step S13: The extrusion head 21 rises 0.3 mm along the Z axis, and the control system synchronously controls the liquid level to rise to the target height according to 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 so, the local spray head module 33 and the ultrasonic array module 32 are automatically triggered. The spray head module 33 precisely aligns with the target area and sprays the treatment liquid. At the same time, the annular ultrasonic auxiliary system 3 rises to the specified height to perform directional ultrasonic treatment. If not, proceed directly to the next step.

[0173] Step S15: Print the current layer;

[0174] Step S16: cyclically execute steps S13 to S15, immersing the entire printed sample in the treatment liquid until the entire model is printed;

[0175] Step S17: After printing is completed, the printed part is kept in a completely immersed state, the ultrasonic generator 53 is set to operate at a frequency of 60 kHz and a power of 50 W, and the printed part is subjected to a comprehensive ultrasonic fine surface repair treatment in a constant temperature treatment solution for 2 hours;

[0176] Step S18: Turn off the annular ultrasonic auxiliary system 3, the ultrasonic generator 53 and the heating assembly 6, and after the solution is naturally cooled to room temperature, discharge the solution through the liquid outlet 52;

[0177] Step S19: Deionized water is introduced into the liquid inlet 51 to completely immerse the printed sample, and the ultrasonic generator 53 is restarted to perform ultrasonic cleaning for 30 minutes to remove surface residues, micro-defects and residual solution by 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 a vacuum drying oven at 80°C for 24 hours.

[0179] Through the above steps, the surface contact angle of the nylon printed part was reduced from 95° before ultrasonic treatment to 25° (the sample without ultrasonic treatment 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 10 μm.

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

[0181] It will be easily understood by those skilled in the art 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 in the scope of protection of the present invention.

Claims

1. A device for improving 3D printing quality, used in conjunction with an FDM 3D printing system, characterized in that: It includes a printing platform (4), a chamber (5), a temperature control system, a ring ultrasonic auxiliary system (3), a liquid circulation system and an infrared liquid level detector (8), wherein: The printing platform (4) is located in 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 a treatment solution and is provided with a liquid inlet (51), a liquid outlet (52) and an ultrasonic generator (53), wherein the liquid inlet (51) and the liquid outlet (52) are respectively connected to the liquid circulation system to achieve the flow and recycling of the solution; the ultrasonic generator (53) is arranged at the bottom of the inner wall of the cavity (5) and is used to apply ultrasonic treatment to the entire sample obtained in the FDM 3D printing process; The temperature control system comprises a heating component (6) and a temperature sensor (54), wherein the temperature sensor (54) is used to sense the temperature of the treatment solution in the cavity (5); the heating component (6) is capable of heating the cavity (5) to maintain the temperature of the treatment solution; 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), wherein the lifting mechanism (34) is used to drive the annular support (31) to move up and down; the ultrasonic array module (32) is arranged on the lower side of the annular support (31) and is evenly distributed along the annular structure, and 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 side wall of the annular support (31), and 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 and is used 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 opened 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 injecting liquid.

2. The device for improving 3D printing quality according to claim 1, wherein: The ultrasonic generator (53) is piezoelectric and supports adjustable frequency control; Preferably, the operating frequency of the ultrasonic generator (53) is adjustable within the range of 40-80 kHz, and the ultrasonic power range is set between 10-80 W.

3. The device for improving 3D printing quality according to claim 1, wherein: The operating frequency of the ultrasonic array module (32) in the annular ultrasonic auxiliary system (3) is 40-50 kHz, and the ultrasonic power is 10-20 W.

4. The device for improving 3D printing quality according to claim 1, wherein: The ultrasonic array module (32) includes a plurality of ultrasonic transducers, an array controller, and a plurality of drive circuits. The ultrasonic transducers are evenly distributed on the lower side of the annular bracket (31). The drive circuits correspond to the ultrasonic transducers one by one. One drive circuit is used to provide input power to one ultrasonic transducer. When the power inputs of any two drive circuits are the same, the ultrasonic power outputs of the corresponding two ultrasonic transducers are also the same. The array controller is used to dynamically adjust the start / stop state, operating frequency, and power output of each transducer by controlling the drive circuit according to printing process information.

5. The device for improving 3D printing quality according to claim 1, wherein: The spray head module (33) comprises a spray head body, an electric pitch drive mechanism, a rotation adjustment mechanism, and a liquid conduit and a sealing connector connected thereto, wherein the electric pitch drive mechanism is driven by a micro-stepping motor or a servo to control the spray head to adjust the pitch angle in a direction perpendicular to the plane where the annular bracket (31) is located; and the rotation adjustment mechanism is used to drive the spray head to adjust the left and right angles within the plane where the annular bracket (31) is located, thereby achieving directional adjustment in the horizontal direction.

6. The device for improving 3D printing quality according to claim 1, wherein: The heating component (6) is a resistance heater, which is arranged at the bottom of the cavity (5); The temperature sensor (54) is a high-precision temperature sensor with a temperature measurement accuracy not inferior to ±0.1°C and is embedded on the inner wall of the cavity (5).

7. The device for improving 3D printing quality according to claim 1, wherein: The liquid circulation system comprises a circulation pump, a filter and a liquid storage tank, wherein the liquid storage tank is used to store the treatment solution, and the liquid storage tank is respectively connected to the liquid inlet (51) and the liquid outlet (52) to form a liquid flow path; the filter is arranged between the liquid outlet (52) and the liquid storage tank, and is used to remove foreign particles in the liquid; the circulation pump is arranged in the liquid flow path, and is used to provide power; Preferably, The liquid inlet (51) and the liquid outlet (52) are respectively arranged at the bottom of two opposite sides of the cavity (5); The filter is a filter screen or an anti-clogging valve; More preferably, The liquid storage tank is equipped with a heating auxiliary component for heating the solution in the liquid storage tank to maintain a constant temperature field; the temperature of the processing solution in the liquid storage tank is stably controlled to be 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; The inlet end of the circulation pump is connected to the outlet of the liquid storage tank, and the outlet end is connected to the liquid inlet (51), for drawing the solution into the cavity (5); The liquid outlet (52) is connected to the inlet end of the liquid storage tank.

8. The device for improving 3D printing quality according to claim 1, wherein: It also includes a computer for temperature control of the device for improving 3D printing quality, lifting control of the annular ultrasonic auxiliary system, liquid circulation control, ultrasonic processing control and spray head control, as well as material extrusion control and printing processing control of the FDM 3D printing system.

9. The device for improving 3D printing quality according to claim 1, wherein: The FDM 3D printing system includes a frame structure, an extrusion head and an extrusion head motion module; Preferably, The annular bracket (31) is made of a corrosion-resistant and high-temperature resistant material capable of withstanding temperatures of ≥300°C; The cavity (5) is made of a high-temperature resistant material that is corrosion-resistant and can withstand temperatures of ≥300°C; the exterior of the cavity (5) is covered with a heat-insulating layer, and the interior wall is precisely polished; The device for improving 3D printing quality and the FDM 3D printing system are both located in a constant temperature environment of the constant temperature housing.

10. A method for improving 3D printing quality by using the device for improving 3D printing quality according to any one of claims 1 to 9 in conjunction with an FDM 3D printing system, characterized in that: The following steps are involved: Step S1: Start the temperature control device of the liquid storage tank to stably control the temperature of the processing solution to be 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 height of the extruder head so that the distance between the extruder head and the printing platform is one printing layer thickness; Step S4: Import the printing model, set the printing parameters, generate the G-code code, and transmit it to the FDM 3D printer control system; Based on the printing path and height changes, a liquid level target curve that changes dynamically with the printing process is preset; wherein the G-code code contains preset key area information; Step S5: injecting a treatment solution into the chamber so that the initial height of the liquid level is lower than the plane of the printing substrate by a thickness of a printing layer; Step S6: Start the liquid level control system and start the dynamic closed-loop control of infrared liquid level detection and treatment liquid replenishment; Step S7: Start the cavity 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; synchronously start the ultrasonic generator (53), set the ultrasonic action frequency to 40-50kHz, and set the power to 10-20W; Step S8: Initialize the annular ultrasonic array module and the showerhead module, and configure the printing layer height recognition and structural feature recognition parameters; Step S9: setting 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 a standby state; Step S10: Start the printing 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 controls the liquid level to rise to the target height according to the signal from the infrared liquid level sensor; Step S12: Determine whether the current printing area is a key area. If so, the annular ultrasonic auxiliary system rises to a specified height, and then automatically triggers the spray head module and the ultrasonic array module. The spray head module precisely aligns with the target area to spray the treatment liquid and implement directional ultrasonic treatment. If not, proceed directly to the next step. Step S13: Print the current layer; After printing is completed, the shower head module is closed and the ultrasonic array module (32) enters a standby state; Step S14: cyclically executing steps S11 to S13, the entire printed sample is immersed in the treatment liquid until the entire model is printed; Step S15: After printing is completed, the printed piece is kept in a completely immersed state in the cavity, and the ultrasonic action frequency of the ultrasonic generator (53) is adjusted to 40-80kHz and the power to 30-80W, so that the printed piece as a whole is fully ultrasonically treated in the constant temperature treatment solution; Step S16: Turn off the annular ultrasonic auxiliary system, the ultrasonic generator (53), and the cavity heating component; Step S17: discharging the treatment solution through the liquid outlet; Step S18: Deionized water is injected through the liquid inlet to completely immerse the printed sample, and the ultrasonic generator is restarted to perform ultrasonic cleaning to remove surface residues, micro defects and residual processing 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: Drying the taken-out printed sample.

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