High-efficiency 3D printing method and device based on surface tension thin-wall structure

Abstract

The present invention discloses a high-efficiency 3D printing method and apparatus based on surface tension thin-walled structures. This method and apparatus address the difficulties and low production efficiency associated with DLP 3D printing, which utilizes high-precision thin-walled structures. The method employs an upper forming ring that moves and rotates in three-dimensional space, while a lower forming ring continuously changes shape according to control system instructions. Surface tension exerts on the printed material, forming a thin-walled tubular film with a predetermined cross-sectional shape between the upper and lower forming rings, completing the printing process. The printing process includes the following steps: preparing the printing material, establishing a three-dimensional model of the thin-walled structure, inputting the three-dimensional model information into a control system, performing 3D printing, removing the sample from the upper forming ring for cleaning and cutting, performing post-processing on the sample, and concluding the printing process.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a high-efficiency 3D printing method and device based on surface tension thin-walled structures. Background Art

[0002] DLP 3D printing technology first uses projection imaging to project the model's slice information onto the print area, where it is exposed to UV light to cure the liquid photosensitive resin. Simultaneously, the forming platform pulls the sample upward, allowing it to continuously solidify and form, ultimately printing a three-dimensional model. The model accuracy of DLP 3D printing is generally superior to that of conventional 3D printers.

[0003] Since its inception, DLP 3D printing technology has been continuously expanding its application areas due to its advantages such as high molding precision and high production efficiency. It has now been used for printing various materials under various working conditions. However, with the deepening of research and the expansion of research scope, DLP technology has also exposed some defects, especially in the preparation of thin-walled structures. Specifically, affected by the resolution of the DLP projection imaging system, DLP 3D printing technology is more difficult to print high-precision thin-walled structural parts, and the production speed and production efficiency of printing thin-walled structural parts are low. Compared with blow molding, blown film and other technologies in industrial production, it is not competitive. Summary of the Invention

[0004] To solve the above problems, the present invention proposes a new DLP 3D printing method for the large-scale and high-efficiency production of thin-walled structural parts: by reducing the surface tension of the DLP printing material - photosensitive resin, a cylindrical film is formed between the upper and lower forming rings with corresponding normal cross-sectional shapes in the printing device, and then cured by ultraviolet light to finally form thin-walled structural parts.

[0005] The present invention proposes an efficient 3D printing device based on surface tension thin-walled structures, including a control system, a forming system, a light curing system and a liquid level maintenance system;

[0006] The forming system includes a six-degree-of-freedom robotic arm, a forming ring frame, an upper forming ring and a lower forming ring;

[0007] The light curing system includes a UV light source and a raw material pool;

[0008] The liquid level maintenance system includes a liquid level sensor, a feed switch and a feed pipe;

[0009] The control system is used to store three-dimensional model information of thin-walled structural parts and extract the central axis information and normal cross-sectional shape information of the thin-walled structural parts from it, thereby planning the motion trajectory of the end of the six-degree-of-freedom robotic arm, the shape of the upper forming ring, and the shape change of the lower forming ring. The control system is also used to control the opening and closing of the UV light source, receive signals from the liquid level sensor, and send signals to the feed switch to control the state of the feed switch.

[0010] The six-degree-of-freedom robotic arm includes a base, a turntable, an upper arm, a lower arm, a rotating arm, a large rotating head and a small rotating head. The base is fixed, and the joint between the base and the turntable constitutes a rotating pair I, so that the robotic arm obtains one degree of freedom; the joint between the turntable and the upper arm constitutes a rotating pair II, so that the robotic arm obtains one degree of freedom; the joint between the upper arm and the lower arm constitutes a rotating pair III, so that the robotic arm obtains one degree of freedom; the joint between the lower arm and the rotating arm constitutes a rotating pair IV, so that the robotic arm obtains one degree of freedom; the joint between the rotating arm and the large rotating head constitutes a rotating pair V, so that the robotic arm obtains one degree of freedom; the joint between the large rotating head and the small rotating head constitutes a rotating pair VI, so that the robotic arm obtains one degree of freedom. The robotic arm has a total of six degrees of freedom in three-dimensional space.

[0011] The six-degree-of-freedom robotic arm follows the instructions of the control system, so that the end of the six-degree-of-freedom robotic arm carries the upper forming ring and plans the motion trajectory in three-dimensional space according to the central axis of the thin-walled structural part. Therefore, the upper forming ring can follow the robotic arm to obtain six degrees of freedom in three-dimensional space, meeting the requirements of printing thin-walled structural parts that are bent and twisted in three-dimensional space;

[0012] The forming ring frame is in the shape of an umbrella, the top of which is connected to the end of the six-degree-of-freedom robot arm through a thread, and the bottom is an annular ring, and the upper forming ring is adsorbed on the bottom ring by magnetic force;

[0013] The upper forming ring is a flexible robot composed of multiple structural units, and its cross-sectional shape can be changed by a control system. The control system obtains the normal cross-sectional shape of the thin-walled structural part by performing normal plane slicing on the thin-walled structural part to be printed, transmits the normal cross-sectional information of the starting part of the thin-walled structural part to the upper forming ring, controls the upper forming ring to deform into the normal cross-sectional shape of the starting part of the thin-walled structural part and keep it unchanged, and the upper forming ring moves upward continuously with the robot arm, so that the sample is continuously solidified, and finally a thin-walled structural part that meets the requirements is obtained;

[0014] The lower forming ring is also a flexible robot composed of multiple structural units, and its cross-sectional shape can be changed by a control system. When not under downward pressure from the upper forming ring, the lower forming ring floats on the liquid surface, with its lower edge immersed in the liquid surface to a depth of 2-3 mm. The control system transmits the normal cross-sectional information of the thin-walled structural part along the central axis to the lower forming ring in real time, so that the lower forming ring continuously changes shape according to the changes in the normal cross-sectional area of ​​the thin-walled structural part during the printing process;

[0015] The UV light sources are evenly distributed along the circumference of the upper edge of the raw material pool, and the light rays emitted by the center points of all light sources pass through the center of the circumference; the number of UV light sources should be reasonably determined according to the circumference of the upper edge of the raw material pool and the radial size of the thin-walled structural parts to ensure that the outer wall of the cylindrical film in the raw material pool is fully exposed to the irradiation of the UV light source;

[0016] The raw material pool is cylindrical and has no cover, and is used to hold the printing material with a low surface tension coefficient and easy film formation - liquid photosensitive resin treated with ultrasound;

[0017] The liquid level sensor in the liquid level maintaining system is located at the upper edge of the inner wall of the raw material pool; the feed switch is located at the bottom of the raw material pool and is controlled by the liquid level sensor; there is a feed channel directly below the feed switch, one end of the feed pipe is connected to the feed channel opening on the base of the raw material pool, and the other end is connected to the raw material reservoir. The liquid level setting value of the liquid level sensor is 2 mm from the upper edge of the raw material pool. When the liquid level of the raw material in the raw material pool is lower than the set value, the liquid level sensor sends a signal to the control system, and the control system turns on the feed switch at the bottom of the raw material pool to replenish the printing material. Until the liquid level reaches the set value, the liquid level sensor sends a signal to the control system again, and the control system turns off the feed switch at the bottom of the raw material pool to stop feeding.

[0018] The present invention proposes an efficient 3D printing method for thin-walled structures based on DLP technology and surface tension, comprising the following steps:

[0019] S1. Printing material preparation:

[0020] This method uses ordinary liquid photosensitive resin, which is mainly composed of oligomer, reactive diluent, photoinitiator and photosensitizer;

[0021] Pretreatment: The liquid photosensitive resin is ultrasonically treated with an ultrasonic power of 40-45W, a treatment time of 4-7 minutes, and an ultrasonic frequency of 18-22KHz. After ultrasonic treatment, the surface tension of the liquid photosensitive resin is reduced from 55-60mN / m to 25-30mN / m, making it easier to form a film.

[0022] S2. Efficient 3D printing process for thin-walled structures:

[0023] Step 1: Establish a three-dimensional model of thin-walled structural parts;

[0024] Step 2: Input the information of the three-dimensional model into the control system, and the control system extracts the central axis information and normal cross-sectional shape information of the thin-walled structural component;

[0025] Step 3, 3D printing: The end of the robotic arm is raised to a suitable position, and the position and shape of the end of the robotic arm and the upper and lower forming rings are adjusted so that the shapes of the upper and lower forming rings are the same as the normal cross-section of the starting part of the thin-walled structural part, and the central axis coincides with the axis of the end of the robotic arm. The robotic arm is vertically lowered to the lower edge of the upper forming ring and immersed in the printing material 2-3mm. The UV light source is turned on to start printing. The lower forming ring changes shape according to the control system command. The robotic arm drives the upper forming ring to rise. The printing material forms a tubular film with a gradient cross-sectional shape between the upper and lower forming rings. The required thin-walled structural part is formed by the movement and rotation of the end of the robotic arm in three-dimensional space. When the bottom of the sample is out of the UV light source, the control system turns off the UV light source;

[0026] Step 4: Remove the sample from the upper forming ring, clean and cut to remove excess uncured photosensitive resin at the end of the sample;

[0027] Step 5, post-processing: irradiate the sample with a UV light source with a power of 95-105W for 9-11 minutes to completely cure the sample.

[0028] The beneficial effects of the present invention are as follows: Traditional DLP 3D printing technology has difficulties and low production speed and efficiency when printing high-precision thin-walled structural parts. The present invention effectively solves these problems by reducing the surface tension of the photosensitive resin and using specially designed upper and lower forming rings to form a cylindrical film and solidify it, thereby improving the printing efficiency of thin-walled structural parts, making this technology more competitive in the field of thin-walled structure preparation, and making up for the shortcomings of DLP technology in this regard. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a simplified structural diagram of a six-degree-of-freedom robotic arm;

[0030] Figure 2 It is a simplified structural diagram of the printing device;

[0031] Figure 3 It is a flow chart of the operation process of the printing device;

[0032] Figure 4 This is a model diagram of a thin-walled structural part.

[0033] The symbols in the accompanying drawings are:

[0034] Control system, molding system, light curing system and liquid level maintenance system;

[0035] Six-degree-of-freedom robotic arm 21, forming ring frame 22, upper forming ring 23, lower forming ring 24; UV light source 31, raw material pool 32; liquid level sensor 41, feed switch 42, feed pipe 43;

[0036] The six-degree-of-freedom robotic arm is represented by: base 211 , turntable 212 , large arm 213 , small arm 214 , rotating arm 215 , large rotating head 216 and small rotating head 217 .

[0037] This implementation case will combine Figures 1 to 4 The specific application process of the efficient 3D printing method and device based on surface tension thin-walled structure is elaborated in detail.

[0038] An efficient 3D printing device based on surface tension thin-walled structures includes a control system, a forming system, a light curing system, and a liquid level maintenance system:

[0039] The forming system includes a six-degree-of-freedom robotic arm 21, a forming ring frame 22, an upper forming ring 23 and a lower forming ring 24;

[0040] The light curing system includes a UV light source 31 and a raw material pool 32;

[0041] The liquid level maintenance system includes a liquid level sensor 41, a feed switch 42 and a feed pipe 43;

[0042] The control system stores the three-dimensional model information of the thin-walled structural part, extracts the central axis information and normal cross-sectional shape information of the thin-walled structural part, plans the motion trajectory of the end of the six-degree-of-freedom robot arm 21, the shape changes of the upper forming ring 23 and the lower forming ring 24, controls the opening and closing of the UV light source 31, receives signals from the liquid level sensor 41, sends signals to the feed switch 42, and controls the state of the feed switch 42;

[0043] The six-degree-of-freedom manipulator 21 includes a base 211, a turntable 212, a large arm 213, a small arm 214, a rotating arm 215, a large rotating head 216 and a small rotating head 217. The base 211 is fixed, and the joint between the base 211 and the turntable 212 constitutes a revolute pair I, so that the manipulator obtains one degree of freedom; the joint between the turntable 212 and the large arm 213 constitutes a revolute pair II, so that the manipulator obtains one degree of freedom; the joint between the large arm 213 and the small arm 214 constitutes a revolute pair III, so that the manipulator obtains one degree of freedom; the joint between the small arm 214 and the rotating arm 215 constitutes a revolute pair IV, so that the manipulator obtains one degree of freedom; the joint between the rotating arm 215 and the large rotating head 216 constitutes a revolute pair V, so that the manipulator obtains one degree of freedom; the joint between the large rotating head 216 and the small rotating head 217 constitutes a revolute pair VI, so that the manipulator obtains one degree of freedom. The manipulator has a total of six degrees of freedom in three-dimensional space.

[0044] The six-degree-of-freedom robotic arm 21 follows the control system's instructions, allowing the upper forming ring 23 at its end to plan a motion trajectory in three-dimensional space along the central axis of the thin-walled structural part. Therefore, the upper forming ring 23 can follow the robotic arm to obtain six degrees of freedom in three-dimensional space, meeting the requirements of printing thin-walled structural parts that bend and twist in three-dimensional space.

[0045] The forming ring frame 22 is umbrella-shaped, with the top connected to the end of the six-degree-of-freedom robot arm 21 by a thread, and the bottom is annular, and the upper forming ring 23 is adsorbed on the bottom ring by magnetic force;

[0046] The upper forming ring 23 is a flexible robot composed of multiple structural units, and its cross-sectional shape can be changed by a control system. The control system obtains the normal cross-sectional shape of the thin-walled structural part by performing normal plane slicing on the thin-walled structural part to be printed. The normal cross-sectional information of the starting portion of the thin-walled structural part is transmitted to the upper forming ring 23, and the upper forming ring 23 is controlled to deform into the normal cross-sectional shape of the starting portion of the thin-walled structural part and keep it unchanged. The upper forming ring 23 moves upward continuously with the robot arm, so that the sample is continuously solidified, and finally a thin-walled structural part that meets the requirements is obtained;

[0047] The lower forming ring 24 is also a flexible robot composed of multiple structural units, and its cross-sectional shape can be changed by a control system. When not under downward pressure from the upper forming ring 23, the lower forming ring 24 floats on the liquid surface, with its lower edge immersed in the liquid to a depth of 2-3mm. The control system transmits the normal cross-sectional information of the thin-walled structural part along the central axis to the lower forming ring 24 in real time, allowing the lower forming ring 24 to continuously change shape according to the changes in the normal cross-sectional area of ​​the thin-walled structural part during the printing process.

[0048] The UV light sources 31 are evenly distributed along the circumference of the upper edge of the raw material pool 32, and the light rays emitted from the center points of all light sources pass through the center of the circumference. The number of UV light sources 31 should be reasonably determined based on the circumference of the upper edge of the raw material pool 32 and the radial size of the thin-walled structural part to ensure that the outer wall of the cylindrical film in the raw material pool 32 is fully exposed to the irradiation of the UV light sources 31.

[0049] The raw material pool 32 is cylindrical and has no cover. It is used to hold the printing material with a low surface tension coefficient and easy film formation - liquid photosensitive resin treated with ultrasound.

[0050] In the liquid level maintaining system, the liquid level sensor 41 is located at the upper edge of the inner wall of the raw material pool 32; the feed switch 42 is located at the bottom of the raw material pool 32 and is controlled by the liquid level sensor 41; there is a feed channel directly below the feed switch 42, and one end of the feed pipe 43 is connected to the feed channel opening on the base 211 of the raw material pool 32, and the other end is connected to the raw material reservoir; the liquid level setting value of the liquid level sensor 41 is 2 mm from the upper edge of the raw material pool 32. When the liquid level of the raw material in the raw material pool 32 is lower than the set value, the liquid level sensor 41 sends a signal to the control system, and the control system turns on the feed switch 42 at the bottom of the raw material pool 32 to replenish printing materials. Until the liquid level reaches the set value, the liquid level sensor 41 sends a signal to the control system again, and the control system turns off the feed switch 42 at the bottom of the raw material pool 32 to stop feeding.

[0051] 1. Printing device construction and preparation

[0052] Device composition and connection: The 3D printing device used in this embodiment mainly consists of a control system, a forming system, a light curing system and a liquid level maintenance system. The forming system includes a six-degree-of-freedom robot arm 21, a forming ring frame 22, an upper forming ring 23 and a lower forming ring 24; the light curing system consists of a UV light source 31 and a raw material pool 32; the liquid level maintenance system includes a liquid level sensor 41, a feed switch 42 and a feed pipe 43. All components are installed and connected according to the design requirements to ensure that the base 211 of the six-degree-of-freedom robot arm 21 is firmly fixed and all joints are firmly fixed. The movement is smooth, the top of the forming ring frame 22 is tightly connected to the end of the robotic arm through threads, and the upper forming ring 23 is firmly adsorbed on the bottom ring of the forming ring frame 22 by magnetic force. The UV light source 31 is evenly installed along the circumference of the upper edge of the raw material pool 32 to ensure that the light rays emitted from the center point of all light sources pass through the center of the circumference. The liquid level sensor 41 is installed at the upper edge of the inner wall of the raw material pool 32, and the feed switch 42 is installed at the bottom of the raw material pool 32. One end of the feed pipe 43 is connected to the feed channel port of the base 211 of the raw material pool 32, and the other end is connected to the raw material storage device.

[0053] Printing Material Preparation: A standard liquid photosensitive resin is used as the printing material. Its main components include an oligomer, a reactive diluent, a photoinitiator, and a photosensitizer. Ultrasonic treatment is used to treat the liquid photosensitive resin. The ultrasonic power is set to 42W, the treatment time is 5 minutes, and the ultrasonic frequency is set to 20kHz. After ultrasonic treatment, the surface tension of the liquid photosensitive resin is reduced from 58mN / m to 28mN / m, making it easier to form a film and meeting printing requirements. After treatment, the liquid photosensitive resin is poured into the raw material pool 32 until the liquid level reaches the appropriate height.

[0054] 2. 3D Printing Process

[0055] Model building and data input: Use professional 3D modeling software to build a 3D model of thin-walled structural parts according to actual needs. After the model is built, its information is input into the control system of the 3D printing device through the data transmission interface. After receiving the model information, the control system automatically extracts the central axis information and normal cross-sectional shape information of the thin-walled structural parts to prepare for subsequent printing operations;

[0056] Adjustment before printing: Start the control system and control the six-degree-of-freedom robotic arm 21 to raise the end of the robotic arm to a suitable position. This position should ensure that the upper forming ring 23 and the lower forming ring 24 will not contact other components during the adjustment process. Then, accurately adjust the position of the end of the robotic arm and the upper forming ring 23 and the lower forming ring 24 so that the central axis of the upper forming ring 23 and the lower forming ring 24 strictly coincide with the axis of the end of the robotic arm. At the same time, based on the normal cross-section information of the starting part of the thin-walled structural part extracted from the control system, control the upper forming ring 23 and the lower forming ring 24 to deform into the corresponding shape. After completing the position and shape adjustment, control the robotic arm to descend vertically so that the lower edge of the upper forming ring 23 is immersed in the printing material, and the immersion depth is controlled at 2.5mm.

[0057] Printing operation: After confirming that the position, shape, and immersion depth of the upper forming ring 23 and the lower forming ring 24 are correct, the UV light source 31 is turned on and 3D printing begins. During the printing process, the lower forming ring 24 continuously changes its shape according to the real-time instructions of the control system to adapt to the changes in the normal cross-section of the thin-walled structural part. The six-degree-of-freedom robotic arm 21 drives the upper forming ring 23 to move and rotate in three-dimensional space according to a pre-planned motion trajectory. Under the action of surface tension, the printing material gradually forms a tubular film with a gradually changing cross-sectional shape between the upper forming ring 23 and the lower forming ring 24. As the robotic arm continues to move, the tubular film continues to solidify, gradually constructing the desired thin-walled structural part;

[0058] Printing end processing: When the bottom of the sample is out of the irradiation of the UV light source 31, it indicates that the sample is printed completely, and the control system automatically turns off the UV light source 31 and stops printing. At this time, carefully remove the sample from the upper forming ring 23 and use a special cleaning fluid to clean the sample to remove the uncured photosensitive resin remaining on the surface of the sample. After cleaning, cut the sample according to the design requirements and remove the excess part. The printing process ends here.

[0059] 3. Post-processing

[0060] The printed sample was irradiated with a 100W UV light source 31 for 10 minutes. This post-processing ensured that the sample was fully cured, improving its mechanical properties and dimensional stability to meet actual usage requirements.

Claims

1. An efficient 3D printing device based on surface tension thin-walled structure, characterized in that: Including control system, forming system, light curing system and liquid level maintenance system: The forming system comprises a six-degree-of-freedom robotic arm (21), a forming ring frame (22), an upper forming ring (23) and a lower forming ring (24); The light curing system includes a UV light source (31) and a raw material pool (32); The liquid level maintaining system includes a liquid level sensor (41), a feed switch (42) and a feed pipe (43); The control system stores three-dimensional model information of the thin-walled structural part, extracts central axis information and normal cross-sectional shape information of the thin-walled structural part, plans the motion trajectory of the end of the six-degree-of-freedom robotic arm (21), the shape of the upper forming ring (23) and the shape change of the lower forming ring (24), controls the opening and closing of the UV light source (31), receives signals from the liquid level sensor (41), sends signals to the feed switch (42), and controls the state of the feed switch (42); The forming ring frame (22) is umbrella-shaped, the top is connected to the end of the six-degree-of-freedom robot arm (21) by a thread, and the bottom is annular, and the upper forming ring (23) is adsorbed on the bottom ring by magnetic force; The upper forming ring (23) is a flexible robot composed of multiple structural units, and the cross-sectional shape of which can be changed by a control system. The control system obtains the normal cross-sectional shape of the thin-walled structural part by performing normal plane slicing on the thin-walled structural part to be printed, transmits the normal cross-sectional information of the starting part of the thin-walled structural part to the upper forming ring (23), controls the upper forming ring (23) to be deformed into the normal cross-sectional shape of the starting part of the thin-walled structural part and keeps it unchanged, and the upper forming ring (23) follows the robot arm to continuously move upward, so that the sample is continuously solidified, and finally a thin-walled structural part that meets the requirements is obtained; The lower forming ring (24) is also a flexible robot composed of multiple structural units and can change its cross-sectional shape through a control system. When not subjected to the downward pressure of the upper forming ring (23), the lower forming ring (24) floats on the liquid surface, and the lower edge is immersed in the liquid surface with a depth of 2-3 mm. The control system transmits the normal cross-sectional information of the thin-walled structural part along the central axis to the lower forming ring (24) in real time, so that the lower forming ring (24) continuously changes its shape according to the change of the normal cross-sectional area of ​​the thin-walled structural part during the printing process.

2. The high-efficiency 3D printing device based on surface tension thin-walled structure according to claim 1, characterized in that: The six-degree-of-freedom robotic arm (21) comprises a base (211), a turntable (212), a large arm (213), a small arm (214), a rotating arm (215), a large rotating head (216) and a small rotating head (217). The base (211) is fixed, and the joint between the base (211) and the turntable (212) constitutes a rotating pair I, so that the robotic arm obtains one degree of freedom; the joint between the turntable (212) and the large arm (213) constitutes a rotating pair II, so that the robotic arm obtains one degree of freedom; the large arm (213) and the small arm (214) constitute a rotating pair II, so that the robotic arm obtains one degree of freedom. The joints between the arms (214) constitute a revolute pair III, so that the robot arm obtains one degree of freedom; the joints between the small arm (214) and the rotating arm (215) constitute a revolute pair IV, so that the robot arm obtains one degree of freedom; the joints between the rotating arm (215) and the large rotating head (216) constitute a revolute pair V, so that the robot arm obtains one degree of freedom; the joints between the large rotating head (216) and the small rotating head (217) constitute a revolute pair VI, so that the robot arm obtains one degree of freedom. The robot arm has a total of six degrees of freedom in three-dimensional space. The six-degree-of-freedom robotic arm (21) follows the instructions of the control system, so that the end of the six-degree-of-freedom robotic arm (21) carries the upper forming ring (23) to plan the motion trajectory in three-dimensional space according to the central axis of the thin-walled structural part. Therefore, the upper forming ring (23) can follow the robotic arm to obtain six degrees of freedom in three-dimensional space, meeting the requirements of printing thin-walled structural parts that are bent and twisted in three-dimensional space.

3. The high-efficiency 3D printing device based on surface tension thin-walled structure according to claim 2, characterized in that: The UV light sources (31) are evenly distributed along the circumference of the upper edge of the raw material pool (32), and the light rays emitted from the center points of all light sources pass through the center of the circumference; the number of UV light sources (31) should be reasonably determined according to the circumference of the upper edge of the raw material pool (32) and the radial size of the thin-walled structural member to ensure that the outer wall of the cylindrical film in the raw material pool (32) is completely exposed to the irradiation of the UV light source (31); The raw material pool (32) is cylindrical and has no cover, and is used to hold a printing material having a low surface tension coefficient and being easy to form a film, namely, a liquid photosensitive resin that has been ultrasonically treated.

4. The high-efficiency 3D printing device based on surface tension thin-walled structure according to claim 3, characterized in that: In the liquid level maintaining system, a liquid level sensor (41) is located at the upper edge of the inner wall of the raw material pool (32); a feed switch (42) is located at the bottom of the raw material pool (32) and is controlled by the liquid level sensor (41); a feed channel is provided directly below the feed switch (42); one end of the feed pipe (43) is connected to the feed channel opening on the base (211) of the raw material pool (32), and the other end is connected to the raw material storage container; the liquid level setting value of the liquid level sensor (41) is 2 mm from the upper edge of the raw material pool (32); when the liquid level of the raw material in the raw material pool (32) is lower than the set value, the liquid level sensor (41) sends a signal to the control system, and the control system turns on the feed switch (42) at the bottom of the raw material pool (32) to replenish the printing material; until the liquid level reaches the set value, the liquid level sensor (41) sends a signal to the control system again, and the control system turns off the feed switch (42) at the bottom of the raw material pool (32) to stop feeding.

5. An efficient 3D printing method for thin-walled structures based on the 3D printing device of claim 4, characterized in that: The following steps are involved: S1. Preparation of printing materials: Ordinary liquid photosensitive resin is selected, which is mainly composed of oligomer, reactive diluent, photoinitiator and photosensitizer. It is subjected to ultrasonic treatment with an ultrasonic power of 40-45W, a treatment time of 4-7min, and an ultrasonic frequency of 18-22kHz to reduce the surface tension from 55-60mN / m to 25-30mN / m; S2. Efficient 3D printing process for thin-walled structures: Step 1: Establish a three-dimensional model of thin-walled structural parts; Step 2: Input the 3D model information into the control system, and the control system extracts the central axis information and normal cross-sectional shape information of the thin-walled structural component; Step 3, 3D printing: the end of the robot arm is raised to a suitable position, and the position and shape of the end of the robot arm and the upper forming ring (23) and the lower forming ring (24) are adjusted so that the shape of the upper forming ring (23) and the lower forming ring (24) are the same as the normal cross-section of the starting part of the thin-walled structural part, and the central axis coincides with the axis of the end of the robot arm. The robot arm is vertically lowered to the lower edge of the upper forming ring (23) and immersed in the printing material 2-3mm, and the UV light source (31) is turned on to start printing. The lower forming ring (24) changes shape according to the control system instruction. The robot arm drives the upper forming ring (23) to rise, and the printing material forms a tubular film with a gradient cross-sectional shape between the upper forming ring (23) and the lower forming ring (24). The required thin-walled structural part is formed by the movement and rotation of the end of the robot arm in three-dimensional space. When the bottom of the sample is separated from the irradiation of the UV light source (31), the control system turns off the UV light source (31); Step 4, remove the sample from the upper forming ring (23), clean and cut to remove excess uncured photosensitive resin at the end of the sample; Step 5, post-processing: irradiate the sample with a UV light source (31) with a power of 95-105 W for 9-11 minutes to completely cure the sample.

Images