3D printing method, runner structure and 3D printing equipment

Abstract

The invention provides a 3D printing method, a flow channel structure and 3D printing equipment. The 3D printing method comprises the steps that a liquid material flows through an open type flow channel, is guided and converged and then is solidified and formed, in the process that the liquid material flows through the open type flow channel, the liquid material forms a thin film to flow on the surface of the open type flow channel, the liquid material flows through the open type flow channel, and when the liquid material flows through a flow channel structure, the thin film flows through the open type flow channel. The cross section of the flow channel structure is an opening pattern, a liquid flow field is changed, and the nozzle wall surface does not generate resistance to an outer side liquid material, so that the problem that the nozzle wall generates resistance to the liquid material to influence flowing of the liquid material is reduced, and the problem of nozzle blockage is solved. The invention further provides a flow channel structure and 3D printing equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and specifically relates to a 3D printing method, a flow channel structure and a 3D printing device. Background Art

[0002] Common liquid material-based additive manufacturing and 3D printing technologies include Direct InkWriting (DIW), Fused Deposition Modeling (FDM), Electrohydrodynamic Printing (EHDP), etc. DIW usually uses slurries with high viscosity, which can be a variety of different materials, including ceramics, metals, polymers or biomaterials, all of which can be formulated into extrudable viscous liquid materials. DIW extrude and deposit the viscous slurry to a specific position through an extruder; during the printing process, the print head is controlled to move precisely along the three-dimensional coordinate system, namely the X-axis, Y-axis and Z-axis, and the slurry is extruded according to the preset path; as the slurry is deposited layer by layer, the extruded lines quickly solidify and maintain their shape, thereby gradually building the desired three-dimensional object. The working principle of FDM is based on the melt extrusion of thermoplastic materials. During the printing process, a solid material filament is fed into the nozzle of the printer; the thermoplastic material is heated to its melting temperature through the heating element inside the nozzle, so that it is converted into a flowable liquid; then, the nozzle is controlled to move along the predetermined X-axis and Y-axis paths, and the liquid thermoplastic material is extruded from the nozzle onto the building platform; the extruded material quickly cools and solidifies after contacting the building platform, thereby forming a stable solid layer; then, the building platform moves along the Z-axis direction for a preset distance equivalent to the thickness of a single layer; the extrusion nozzle continues to operate, and another layer of thermoplastic material is extruded according to the predetermined path, and the layer of material is tightly bonded to the previously solidified layer; the above extrusion and stacking process is repeated until a complete three-dimensional object is constructed in sequence. This type of printing method usually uses a traditional inner flow channel nozzle for material extrusion and object processing and preparation. During the printing process, the liquid material flows through the inner flow channel of the nozzle under the action of the driving force and is extruded and deposited. EHDP is a precision additive manufacturing technology that uses electric field forces to control and guide the ejection of liquid materials to achieve micron or even nanometer printing resolution. EHDP is based on electrohydrodynamics, which uses an electric field to move charged fluids. In EHDP, the printing material is loaded into a nozzle with a tiny nozzle. A high voltage is applied between the nozzle and the substrate to form a strong electric field. When the electric field strength exceeds the threshold, the charge force on the surface of the droplet overcomes the surface tension, resulting in the formation of a sharp droplet tip at the nozzle tip, called a Taylor cone. As the electric field is further enhanced, a thin jet stream is emitted from the tip of the Taylor cone for printing, and the stream can be in the form of continuous or intermittent droplets.

[0003] The above-mentioned technical means of additive manufacturing and 3D printing based on liquid materials, the main implementation plan is to print through the inner flow channel nozzle. Before printing, the required material is converted into a liquid material (such as by configuration, thermal phase change, etc.). During printing, the fluid flows in the nozzle under the action of the driving force and is extruded at the nozzle head. The inner wall of the nozzle produces a viscous force on the fluid, hindering the flow of the fluid. The flow velocity of the flow field inside the nozzle is greater the closer to the axis, and the fluid converges to the center when it flows. When using inner flow channel printing, the size of the nozzle head directly affects the size of the printed line, the difficulty of extrusion and the degree of clogging. The smaller the nozzle, the higher the accuracy of the printed line, but the difficulty of extrusion becomes greater and the degree of clogging becomes higher, especially for liquid inks and polymer filaments containing particles or fibers. In order to achieve high-precision printing processing, people often use smaller nozzles, which greatly increases the difficulty of material extrusion and the degree of clogging, and also increases time, manpower and money costs.

[0004] In the printing process of traditional internal flow channel nozzles, the printing process of high-resolution features, high viscosity, high surface tension and liquid materials containing particles or fibers is accompanied by problems such as difficulty in extrusion, inability to extrude and easy nozzle clogging. Therefore, it is necessary to develop a new 3D printing method. Summary of the invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the present invention provides a 3D printing method, which solves the problem that the inner wall of the nozzle generates resistance to the liquid material, and after the liquid material is diverted and converged, the problem of nozzle clogging is solved.

[0006] The invention also provides a flow channel structure.

[0007] The invention also provides a 3D printing device.

[0008] The first aspect of the present invention provides a 3D printing method, comprising the steps of liquid material flowing through an open flow channel, being guided, converged and then solidified into a shape. During the process of the liquid material flowing through the open flow channel, the liquid material forms a thin film flow on the surface of the open flow channel.

[0009] One of the technical solutions of the 3D printing method of the present invention has at least the following beneficial effects:

[0010] In the 3D printing method of the present invention, the liquid material flows through an open flow channel. When the fluid flows through the flow channel structure, the cross-section of the flow channel structure is an open figure, which will not generate resistance to the liquid material, thereby solving the problem of the inner wall of the nozzle generating resistance to the liquid material. The liquid material is guided and converged before solidifying and forming, thereby solving the problem of nozzle clogging.

[0011] When the liquid material flows through the open flow channel, the liquid material forms a thin film flow on the surface of the open flow channel, which can effectively avoid fluid blockage. Specifically:

[0012] 1. It can reduce flow resistance: Compared with the flow that flows completely through a closed channel, the thin film flow formed under the external flow channel only contacts the wall on one side (inner side), and the surface friction of the outer side in contact with the open environment is smaller. Because the contact area between the liquid material and the flow channel is reduced, the surface tension effect is relatively uniform, which reduces the resistance of the liquid material when flowing in the flow channel, helps the liquid material flow smoothly and avoids blockage.

[0013] 2. Reduce the contact area with the wall and distribute it more evenly, which can improve the printing effect of liquid containing reinforcing materials: reinforcing materials are easy to accumulate in the boundary layer generated by the liquid material and the wall when it flows. The thin film flow formed by the liquid material on the surface of the open flow channel only contacts the wall on one side, which reduces the boundary layer generated with the wall during flow and helps to distribute the liquid material more evenly. Especially for composite materials containing particles or fibers, the thin film flow can reduce the stacking ratio of reinforcing materials (such as particles or fibers) so that the reinforcing materials are more evenly distributed, which helps to enhance the printing effect.

[0014] 3. The open flow environment can prevent nozzle blockage caused by particle or fiber accumulation: the reinforcement material is easy to accumulate in the boundary layer between the liquid material and the wall surface when it flows. The open flow channel environment ensures the full flow of the material, and the concentrated accumulation of reinforcement material in the local position near the wall surface will not cause the overall blockage of the nozzle.

[0015] 4. Improved material fluidity during printing: Thin film flow allows liquid materials to present a smoother flow pattern, which not only reduces resistance, but also avoids low or zero fluidity due to material adhesion and accumulation, especially in the printing of high viscosity or composite materials.

[0016] 5. Improved printing accuracy: Thin film flow can more accurately control the flow and distribution of liquid materials, avoid reduced printing accuracy due to material accumulation or solidification, and ensure the printing of higher precision and more complex structures.

[0017] As a result, thin-film flow reduces the direct contact between the liquid and the channel wall, reduces flow resistance, and helps avoid printing problems caused by uneven flow or blockage. These advantages are especially important for high viscosity, composite materials, and high-precision printing.

[0018] In the 3D printing method of the present invention, the liquid material flows through an open flow channel, that is, the liquid material is squeezed out of the cavity by feeding through an external flow channel, and the liquid material can flow down along the outer wall of the nozzle and form a flowing liquid film. Finally, the liquid material converges at the tip of the nozzle and is deposited and solidified on the substrate in the form of a liquid or a liquid bridge. The 3D printing method proposed in the present invention changes the flow field and flow pattern of the liquid material by forming a uniform thin film flow of the fluid on the outer wall of the nozzle, and can achieve high-precision extrusion or jet printing of high-viscosity, high-surface tension, and composite fluids, solving the problem that traditional nozzles are difficult to extrude the above materials or are prone to blockage. In addition, the 3D printing method can be combined with a variety of external energy fields such as thermal fields, electric fields, and magnetic fields to achieve high-forming precision 3D printing of multiple materials and composite materials.

[0019] The 3D printing method of the present invention solves the extrusion difficulty and clogging problems encountered by traditional internal flow channel nozzles when processing high-viscosity, high-surface tension and composite liquid materials under high-precision printing.

[0020] In the 3D printing method of the present invention, the open flow channel is the outer flow channel, and the printing accuracy has no direct relationship with the size of the cavity outlet. When printing lines of the same size, the outlet area can be several times that of the inner flow channel needle, which greatly reduces the difficulty of extrusion and reduces the possibility of clogging. At the same time, this also means that more materials with high viscosity, surface tension and fiber-reinforced composite materials that are difficult to print with traditional inner flow channels can be printed with high precision. In addition, due to the openness of the outer flow channel structure, the cleaning and maintenance of the nozzle during the printing process becomes simpler, effectively improving the printing efficiency and stability of the equipment.

[0021] According to some embodiments of the present invention, when the liquid material flows through the open flow channel, the flow velocity of the liquid material gradually increases along the radial direction from the inner side close to the flow channel wall to the outer side away from the flow channel wall.

[0022] According to some embodiments of the present invention, the 3D printing method also includes the step of the liquid material flowing through the open flow channel, being guided and converged, forming a liquid column or breaking into droplets at the tail end of the open flow channel, and flowing down in the direction of gravity to be deposited and solidified on the substrate.

[0023] The second aspect of the present invention provides a flow channel structure for implementing the 3D printing method of the first aspect of the present invention, wherein the cross section of the flow channel structure is an opening pattern.

[0024] One of the technical solutions of the present invention regarding the flow channel structure has at least the following beneficial effects:

[0025] The flow channel structure with open graphics has significant advantages in 3D printing. It ensures that liquid materials can flow through the flow channel more smoothly and evenly by reducing flow resistance, reducing the risk of clogging, optimizing flow patterns and improving material fluidity, avoiding the friction, accumulation and curing problems common in traditional closed flow channels. Especially in high-viscosity, composite materials and high-precision printing, open flow channels can effectively prevent clogging, increase printing speed and precision, and improve molding quality. Overall, this design improves the stability, efficiency and reliability of the printing process.

[0026] According to some embodiments of the present invention, the cross-sectional area of ​​the flow channel structure gradually decreases from the upstream direction to the downstream direction of the flow of the liquid material.

[0027] According to some embodiments of the present invention, the material of the flow channel structure includes at least one of resin, stainless steel, aluminum oxide and tungsten.

[0028] According to some embodiments of the present invention, from the direction of flow of the liquid material, the flow channel structure is divided into a cavity and a nozzle.

[0029] According to some embodiments of the present invention, the first end of the cavity is provided with a Luer connector or a threaded structure.

[0030] A third aspect of the present invention provides a 3D printing device, comprising the flow channel structure of the second aspect of the present invention.

[0031] One of the technical solutions of the present invention regarding the 3D printing device has at least the following beneficial effects:

[0032] The 3D printing device of the present invention adopts an open graphic flow channel structure, which significantly improves printing efficiency and precision, reduces the risk of clogging, and is particularly suitable for high-viscosity, composite materials and high-precision printing. The design optimizes material flow, simplifies cleaning and maintenance, and expands the device's adaptability to complex materials. By reducing flow resistance and extrusion difficulty, the device can work stably and efficiently, improves printing quality and device stability, and meets diverse printing needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the x-plane and y-plane cross-section of an open external flow channel printing needle.

[0034] Figure 2 It is a schematic diagram of the cross section and profile of an open external flow channel.

[0035] Figure 3 It is a schematic diagram of the cross section and profile of a traditional closed flow channel.

[0036] Figure 4 It is a schematic diagram of the process when liquid material flows through an open flow channel.

[0037] Figure 5 It is a schematic diagram combining different field printings. DETAILED DESCRIPTION

[0038] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0039] In a first aspect, some embodiments of the present invention provide a 3D printing method, comprising the steps of liquid material flowing through an open flow channel, being guided, converged, and then solidified into shape, wherein during the process of the liquid material flowing through the open flow channel, the liquid material forms a thin film flow on the surface of the open flow channel.

[0040] In the printing process of traditional internal flow channel nozzles, the printing process of liquid materials with high resolution features, high viscosity, high surface tension and containing particles or fibers is accompanied by problems such as difficulty in extrusion, inability to extrude and easy clogging of the nozzle. Such problems arise mainly due to the resistance of the inner wall of the nozzle to the liquid material when the liquid material flows. The size of this resistance is closely related to the nozzle size, the characteristics of the liquid material and the composition of the liquid material. Generally, the greater the viscosity of the liquid material, the smaller the nozzle size, and the more complex the composition of the liquid material, the greater the resistance of the inner wall of the nozzle to the liquid material, and the more difficult it is for the liquid material to be extruded. At the same time, liquid printing materials containing particles and fiber reinforcements are also prone to accumulation and solidification in the nozzle, blocking the nozzle. With the increasing requirements of today's industrial production and scientific research, additive manufacturing needs to handle the processing and preparation of more complex materials, higher precision and higher performance objects, such as: a) When performing high-precision printing, the nozzle size is too small, resulting in 1) difficulty in forming liquid materials, 2) difficulty or inability to extrude liquid materials, 3) accumulation of composite materials in the nozzle, causing nozzle clogging, 4) premature solidification of liquid materials, clogging the nozzle; b) When printing high-viscosity materials, the resistance of liquid materials flowing through the wall of the inner flow channel is too large, resulting in 1) difficulty in forming liquid materials, 2) difficulty or inability to extrude liquid materials, 3) accumulation of composite materials in the nozzle, causing nozzle clogging, 4) premature solidification of liquid materials, clogging the nozzle; c) When printing composite materials such as particle or fiber reinforcement, the flow field is uneven, resulting in 1) difficulty in forming liquid materials, 2) difficulty or inability to extrude liquid materials, 3) accumulation of reinforcing materials such as fibers / particles, clogging the nozzle, 4) premature solidification of liquid materials, clogging the nozzle. In traditional nozzles and printing methods, when the fluid flows through the nozzle, the cross-section of the nozzle is a closed shape, and the inner wall of the nozzle will produce resistance to the liquid material.

[0041] Figure 2 It is a schematic diagram of the cross section and profile (including velocity field) of an open external flow channel. Figure 3It is a schematic diagram of the cross section and profile (including velocity field) of a traditional closed flow channel. It can be seen that in the present invention, the open flow channel is different from the traditional closed flow channel structure. The top, both sides or multiple directions of the flow channel are open, allowing the fluid to flow freely without obvious wall obstruction. In the present invention, the open flow channel means that the path for the flow of liquid material is not completely surrounded or closed, but adopts an open structural design to enable the liquid to flow freely in the flow channel and reduce contact with the flow channel wall.

[0042] The open flow channel of the present invention has at least the following characteristics:

[0043] 1. No closed wall: Compared with the traditional nozzle design, the cross-section of the open flow channel is not a closed pipe shape, but an open shape, so that the liquid material will not completely contact the inner wall, thus avoiding the friction and resistance in the traditional closed flow channel.

[0044] 2. Reduced flow resistance: Since the liquid is not subject to strong friction or shear force from the inner wall when it flows, the flow resistance of the liquid is smaller, especially in liquids with high viscosity or containing reinforcing materials such as particles and fibers, the flow is smoother.

[0045] 3. Avoids clogging: The open flow channel design allows the liquid to flow smoothly, reducing the possibility of material accumulation and solidification at the nozzle causing clogging, especially when printing high viscosity or composite materials. Traditional closed flow channels are prone to clogging the nozzle due to fluid retention and premature solidification.

[0046] 4. More flexibility and precision: In some high-precision, high-performance printing applications, open channels can provide more flow control capabilities. By adjusting the width and shape of the channel, the flow pattern of the fluid can be optimized and the precision and quality of the printing process can be improved.

[0047] 5. Forming thin film flow: In an open flow channel, the flow of liquid material usually forms a thin film flow on the surface of the flow channel. This flow pattern helps to reduce flow resistance and avoid the liquid material from solidifying too quickly, thereby improving the stability and reliability of printing.

[0048] In 3D printing or additive manufacturing, the benefits brought by the printing method of the present invention are mainly reflected in the following aspects:

[0049] Printing of high-viscosity materials: For high-viscosity liquids, traditional nozzle designs are prone to poor flow, making it difficult to extrude the material. The open flow channel design reduces the contact between the liquid and the inner wall, reducing resistance, making the printing of high-viscosity liquids more feasible.

[0050] Printing of composite materials: Composite materials containing particles or fibers are often prone to clogging in traditional closed channels due to their inherent structure or flow characteristics. The open channel structure can effectively avoid this problem and provide a smoother printing process.

[0051] High-precision printing: In applications requiring high precision, the flow of liquid materials requires more precise control. Open flow channels can provide greater flexibility, making the flow of materials during printing more controllable and avoiding printing problems caused by uneven flow or excessive resistance.

[0052] Therefore, in the printing method of the present invention, the design of the open flow channel can not only reduce flow resistance and avoid nozzle clogging, but also effectively improve the smoothness of the printing process, and is particularly suitable for applications with high viscosity, composite materials, and high-precision printing. By reducing the friction and contact between the liquid and the flow channel wall, the open flow channel provides a more efficient and stable liquid printing solution.

[0053] In combination with the first aspect, in some embodiments of the present invention, reference Figure 2 , Figure 4 and Figure 5 As shown, during the process of the liquid material flowing through the open flow channel, the flow velocity of the liquid material gradually increases along the radial direction from the inner side close to the flow channel wall to the outer side away from the flow channel wall.

[0054] It should be noted that the flow rate of liquid materials in the open flow channel gradually increases radially, which helps to optimize the flow pattern, reduce flow resistance and material accumulation, and improve printing accuracy. Through uniform flow rate distribution, this design can effectively control the flow of liquid materials and avoid blockage. It is particularly suitable for printing high viscosity and composite materials, ensuring smoother and more efficient flow, and improving printing quality and stability.

[0055] It should also be noted that if Figure 5 As shown, the 3D printing method of the present invention can combine various external energy fields such as thermal field, electric field, magnetic field, etc. to achieve high forming precision 3D printing of multiple materials and composite materials.

[0056] Figure 5 Among them, (a) is the printing method under normal circumstances with an external flow channel nozzle; (b) and (c) are printing methods under electromagnetic induction heating; (d) is the printing method under laser heating; and (e) is the printing method under electric heating.

[0057] In combination with the first aspect, in some embodiments of the present invention, the 3D printing method also includes the step of the liquid material flowing through the open flow channel, being guided and converged, forming a liquid column or breaking into droplets at the tail end of the open flow channel, and flowing down in the direction of gravity to be deposited and solidified on the substrate.

[0058] In a second aspect, in some embodiments of the present invention, a flow channel structure for implementing the 3D printing method of the first aspect of the present invention is provided, wherein the cross section of the flow channel structure is an opening pattern.

[0059] The design of the cross-section of the flow channel structure being an open pattern (i.e., an open flow channel structure) has the following significant beneficial effects in implementing the 3D printing method of the first aspect of the present invention:

[0060] 1. It can reduce flow resistance. The cross section of the flow channel is an open figure, which means that the two sides or multiple directions of the flow channel are open, so that the flow of liquid materials will not be subject to strong friction and resistance from the closed flow channel wall. Compared with the traditional closed flow channel, the open flow channel significantly reduces the friction and flow resistance of the liquid flow, allowing the liquid material to flow through the flow channel more smoothly, thereby improving the flow efficiency and extrusion performance of the liquid material.

[0061] 2. Reduced risk of clogging. In traditional 3D printing methods, the flow of liquid materials in the flow channel is often affected by the friction and deposition of the inner wall, resulting in material accumulation and clogging. The flow channel structure with an open pattern can avoid excessive contact between the liquid material and the flow channel wall due to its openness, reduce the risk of material solidification, adhesion or accumulation, and reduce the probability of nozzle clogging. This is especially important for high-viscosity materials or composite materials containing particles or fiber reinforcements.

[0062] 3. Optimized flow pattern. When the flow channel cross section is designed as an open pattern, the flow of the fluid is more uniform, and the flow pattern of the liquid can be optimized by adjusting the shape and size of the flow channel opening, further improving the flow control during printing. This optimization can keep the liquid material flowing stably in the flow channel, avoiding printing defects caused by uneven flow, such as extrusion of too much or too little material.

[0063] 4. Improved material fluidity and controllability. The open channel structure can provide higher fluidity and controllability. Due to its less flow resistance, liquid materials can be more accurately controlled during the printing process. Especially in the printing of high viscosity and composite materials (such as liquids containing particles or fibers), the open graphic flow channel can effectively avoid printing failures caused by adhesion, retention or blockage, and ensure the stability of liquid materials.

[0064] 5. Improved printing accuracy and molding quality. The design of the flow channel section as an open pattern allows the liquid material to maintain a more stable flow and avoids shape distortion caused by excessive resistance or material accumulation. This design helps to achieve better molding quality in high-precision printing, making the printed objects more accurate and smoother.

[0065] 6. Premature solidification is avoided. In the traditional internal flow channel design, the flow of liquid materials usually causes local temperature rise due to friction, which accelerates the solidification of the material and causes blockage. The open flow channel design reduces the contact with the flow channel wall, avoids this temperature accumulation, reduces the risk of premature solidification of liquid materials, and ensures the stability of the printing process.

[0066] 7. Able to adapt to the printing of complex materials. For the printing of high-performance composite materials, such as liquid materials containing reinforcing particles or fibers, the flow channel structure with open patterns can better adapt to the characteristics of these materials. Since composite materials may have high viscosity or uneven fluidity, traditional closed flow channels are prone to deposition or blockage of reinforcing materials, while open flow channels can effectively reduce the occurrence of these problems by reducing flow resistance and improving flow patterns.

[0067] 8. Increased printing speed. Due to the small flow resistance and smoother flow of liquid materials, the open channel can achieve a higher extrusion rate under the same conditions, thereby increasing the speed of 3D printing. Especially when performing large-scale printing, the open channel design can significantly shorten the printing time.

[0068] In combination with the second aspect, in some embodiments of the present invention, the cross-sectional area of ​​the flow channel structure gradually decreases from the upstream direction to the downstream direction of the flow of the liquid material.

[0069] As the cross-sectional area of ​​the flow channel gradually decreases, the flow rate of the liquid material will increase accordingly. This design helps to generate sufficient pressure in the downstream area to promote the smooth extrusion or injection of liquid materials, and is particularly suitable for printing high-viscosity materials. By precisely controlling the flow rate and pressure, the extrusion volume and fluidity of the material can be better controlled, thereby improving printing accuracy. The gradual reduction in the cross-sectional area of ​​the flow channel allows the liquid material to be guided to a narrower area in the flow channel, increasing the concentration of the fluid and helping the material flow to flow more concentratedly and evenly to the nozzle. Especially in the printing of composite materials, it can effectively avoid the accumulation of particles or fibers and reduce the risk of nozzle clogging.

[0070] In combination with the second aspect, in some embodiments of the present invention, the material of the flow channel structure includes at least one of resin, stainless steel, aluminum oxide and tungsten.

[0071] It can be understood that due to the openness of the flow channel structure, it is easy to perform various processing on its surface to achieve better results. For example, the surface macro or micro structure can be modified, and the surface of the flow channel structure can be designed with a certain micro / macro structure, and prepared by etching, finishing, electroplating, etc. to change the surface energy gradient, wettability and other characteristics of the flow channel structure surface for better printing.

[0072] It can also be understood that compared with the inner flow channel nozzle, the outer flow channel structure is easier to process, so more materials can be used to prepare the outer flow channel nozzle to meet different printing needs: for example, when performing fused deposition modeling (FDM) outer flow channel printing, high temperature resistant metal (such as 304 stainless steel) materials can be used to prepare the outer flow channel, and when performing electrohydrodynamic jet printing (EHD) outer flow channel printing, metal materials with good electrical conductivity (such as copper materials) can be used to prepare the outer flow channel. In addition, for different printing materials, selecting materials with poor mutual adhesion for outer flow channel preparation is conducive to cleaning the outer flow channel nozzle during printing.

[0073] It should be noted that compared with the inner channel nozzle, the outer channel structure is easier to control the printing process by external fields. For example, the essence of FDM outer channel printing and EHD outer channel printing is to use thermal and electric fields to intervene and control the printing process. In order to print more materials and achieve more functions and higher quality of finished products, external fields such as light and magnetism can also be used for intervention and control.

[0074] In combination with the second aspect, in some embodiments of the present invention, the tail end of the flow channel structure is in the shape of a Taylor cone.

[0075] When printing the EHD outer channel, the outer channel nozzle is processed into a Taylor cone (cone angle 98.6°) shape, which is easy to break through the surface tension of the liquid and use a small driving voltage to form a liquid column or liquid jet at the tip of the channel structure (outer channel nozzle).

[0076] In combination with the second aspect, in some embodiments of the present invention, from the direction of flow of the liquid material, the flow channel structure is divided into a cavity and a nozzle.

[0077] In combination with the second aspect, in some embodiments of the present invention, a Luer connector or a threaded structure is provided at the head end of the cavity.

[0078] It is understandable that the head end of the cavity is provided with a standard Luer connector or thread for easy standardized installation. After the liquid material flows out of the cavity, a liquid film flows on the outer wall of the nozzle.

[0079] The 3D printing method, flow channel structure and 3D printing equipment of the present invention can process a wider range of printing materials, including high-performance plastics, composite materials, biocompatible materials, etc., which will apply additive manufacturing in more fields, promote the research and development and manufacturing of new products, and provide consumers with more diverse product choices.

[0080] Since the nozzle is not clogged, the equipment maintenance requirements and downtime are reduced. At the same time, the ability to print multiple materials means that a single device can handle more production needs, significantly improving the flexibility and efficiency of the manufacturing process.

[0081] Furthermore, reducing nozzle clogging and expanding material compatibility can reduce material waste and production costs, enhance the market competitiveness of enterprises, and may prompt the manufacturing industry to develop in the direction of low cost and high quality.

[0082] Furthermore, the compatibility of more materials means that the personalized needs of different customers can be met, which will promote customized production to become the mainstream and increase consumer satisfaction and market demand.

[0083] Understandably, schools and research institutions can use this technology to conduct more extensive experiments and explorations, promoting the development of science and technology education and innovative research.

[0084] It is easy to imagine that the 3D printing method, flow channel structure and 3D printing equipment of the present invention can enhance the market's confidence in additive manufacturing technology, increase the demand for additive manufacturing companies in the market, and promote the development of additive manufacturing in the manufacturing industry.

[0085] It should be noted that the printing accuracy of the outer flow channel of the present invention has no direct relationship with the size of the cavity outlet. When printing lines of the same size, the outlet area can be several times that of the inner flow channel needle, which greatly reduces the difficulty of extrusion and reduces the possibility of clogging. At the same time, this also means that more materials with high viscosity, surface tension and fiber-reinforced composite materials that are difficult to print with traditional inner flow channels can be printed with high precision. In addition, due to the openness of the outer flow channel structure, the cleaning and maintenance of the nozzle during the printing process becomes simpler, effectively improving the printing efficiency and stability of the equipment.

[0086] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0087] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0088] Unless otherwise specified, "room temperature" in the present invention means 25°C±5°C.

[0089] Unless otherwise specified, "about" in the present invention means that the allowable error is within ±2%.

[0090] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0091] It should be noted that in the following embodiments, the printing materials and process parameters used are all existing process parameters.

[0092] Example 1

[0093] Combine slurry direct writing technology to print metal powder, the specific metal is iron. The steps are:

[0094] (1) Using digital photocuring printing technology, an open flow channel structure printing nozzle of resin material is prepared, the structure is as follows Figure 1 As shown, Figure 1 In the figure, the left side is a schematic diagram of the x-plane cross-section of the open external flow channel printing needle, and the right side is a schematic diagram of the y-plane cross-section of the open external flow channel printing needle;

[0095] (2) Post-processing the printed open channel structure printing nozzle, including:

[0096] 1) Remove the support structure generated by printing on the nozzle;

[0097] 2) Soak the nozzle in anhydrous ethanol and clean it ultrasonically for 6 minutes;

[0098] 3) Blow dry the nozzle and perform secondary curing on the nozzle;

[0099] (3) preparing a uniform iron metal powder slurry using polyvinyl alcohol, polyethylene glycol polylactic acid and iron powder;

[0100] (4) Filling the iron metal powder slurry into a barrel and installing it in a slurry direct writing printing device;

[0101] (5) Install the outer flow channel printing nozzle to the bottom of the barrel;

[0102] (6) Start printing and apply a driving force to squeeze the iron slurry from the barrel into the nozzle cavity;

[0103] (7) The iron slurry is driven by the driving force and flows out of the nozzle cavity, flows on the outer wall of the nozzle head, forms a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then prints the sample piece step by step according to the preset program;

[0104] (8) After printing, let the printed sample stand at room temperature for 12 hours.

[0105] (9) The printed sample is heat treated so that the iron powders are sintered together to form a whole, thus forming the final sample.

[0106] During the printing process, due to the large outlet area of ​​the cavity, only 4kPa of air pressure is required to smoothly squeeze out the iron slurry. After the iron slurry is driven out of the nozzle cavity by the driving force, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head, forming a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0107] Example 2

[0108] Combine slurry direct writing technology to print ceramic powder, the specific ceramic is zirconium oxide. The steps are:

[0109] (1) Using digital photocuring printing technology, an open flow channel structure printing nozzle of resin material is prepared, the structure is as follows Figure 1 As shown;

[0110] (2) Post-processing the printed open channel structure printing nozzle, including:

[0111] 1) Remove the support structure generated by printing on the nozzle;

[0112] 2) Soak the nozzle in anhydrous ethanol and clean it ultrasonically for 6 minutes;

[0113] 3) Blow dry the nozzle and perform secondary curing on the nozzle;

[0114] (3) preparing a zirconia ceramic powder slurry having uniform properties by using acetone, sodium polyacrylate and zirconia powder;

[0115] (4) Filling the zirconium oxide ceramic powder slurry into a barrel and installing it in a slurry direct writing printing device;

[0116] (5) Install the outer flow channel printing nozzle to the bottom of the barrel;

[0117] (6) Start printing and apply a driving force to squeeze the iron slurry from the barrel into the nozzle cavity;

[0118] (7) The zirconia ceramic powder slurry is driven by the driving force and flows out of the nozzle cavity, flows on the outer wall of the nozzle head, forms a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then prints the sample step by step according to the preset program;

[0119] (8) After printing, let the printed sample stand at room temperature for 12 hours.

[0120] (9) The printed sample is heat treated so that the iron powders are sintered together to form a whole, thus forming the final sample.

[0121] During the printing process, due to the large outlet area of ​​the cavity, only 1kPa of air pressure is required to smoothly extrude the ceramic slurry. After the ceramic slurry is driven by the driving force to flow out of the nozzle cavity, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0122] Example 3

[0123] Implementation case 3 combines slurry direct writing technology to print graphene powder, the steps are:

[0124] (1) Using digital photocuring printing technology, an open flow channel structure printing nozzle of resin material is prepared, the structure is as follows Figure 1 As shown;

[0125] (2) Post-processing the printed open channel structure printing nozzle, including:

[0126] 1) Remove the support structure generated by printing on the nozzle;

[0127] 2) Soak the nozzle in anhydrous ethanol and clean it ultrasonically for 6 minutes;

[0128] 3) Blow dry the nozzle and perform secondary curing on the nozzle;

[0129] (3) preparing a graphene powder slurry with uniform properties by using dimethylformamide, polylactic acid, polyvinyl pyrrolidone and graphene powder;

[0130] (4) using a vacuum degassing machine to remove bubbles in the graphene powder slurry;

[0131] (5) Filling graphene powder slurry into a barrel and installing it in a slurry direct writing printing device;

[0132] (6) Install the outer flow channel printing nozzle to the bottom of the barrel;

[0133] (7) Start printing and apply a driving force to squeeze the iron slurry from the barrel into the nozzle cavity;

[0134] (8) Driven by the driving force, the graphene powder slurry flows out of the nozzle cavity, flows on the outer wall of the nozzle head, forms a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then gradually prints the sample according to the preset program;

[0135] (9) After printing, let the printed sample stand at room temperature for 12 hours.

[0136] (10) The printed sample is heat treated so that the iron powders are sintered together to form a whole, thereby forming the final sample.

[0137] During the printing process, due to the large outlet area of ​​the cavity, only 1kPa of air pressure is required to smoothly extrude the graphene powder slurry. After the graphene powder slurry is driven by the driving force to flow out of the nozzle cavity, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0138] Example 4

[0139] Combined with the slurry direct writing technology to print high-load fiber-reinforced thermosetting resin slurry, specifically carbon fiber reinforced epoxy resin composite material, the steps are as follows:

[0140] (1) Using digital photocuring printing technology, an open flow channel structure printing nozzle of resin material is prepared, the structure is as follows Figure 1 As shown;

[0141] (2) Post-processing the printed open channel structure printing nozzle, including:

[0142] 1) Remove the support structure generated by printing on the nozzle;

[0143] 2) Soak the nozzle in anhydrous ethanol and clean it ultrasonically for 6 minutes;

[0144] 3) Blow dry the nozzle and perform secondary curing on the nozzle;

[0145] (3) Drying the T700 carbon fiber;

[0146] (4) A carbon fiber reinforced epoxy resin slurry with uniform properties is prepared by using bisphenol A epoxy resin, T700 carbon fiber, methyltetrahydrophthalic anhydride, dimethyl sulfoxide, hydrophobic silane and polyvinyl pyrrolidone;

[0147] (5) Filling the carbon fiber reinforced epoxy resin slurry into the barrel and installing it in the slurry direct writing printing device;

[0148] (6) Install the outer flow channel printing nozzle to the bottom of the barrel;

[0149] (7) Start printing and apply a driving force to squeeze the iron slurry from the barrel into the nozzle cavity;

[0150] (8) The carbon fiber reinforced epoxy resin slurry is driven by the driving force to flow out of the nozzle cavity, flow on the outer wall of the nozzle head, form a thin film flow, and converge at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then gradually prints the sample according to the preset program;

[0151] (9) Place the printed sample in a constant temperature box for heating and curing to ensure that the epoxy resin is fully cross-linked.

[0152] During the printing process, due to the large outlet area of ​​the cavity, only 1kPa of air pressure is required to smoothly squeeze out the resin slurry. After the resin slurry is driven by the driving force to flow out of the nozzle cavity, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0153] Example 5

[0154] Combine slurry direct writing technology to print high-load magnetic particle slurry, specifically Fe3O4 magnetic nanoparticle slurry. The steps are:

[0155] (1) Using digital photocuring printing technology, an open flow channel structure printing nozzle of resin material is prepared, the structure is as follows Figure 1 As shown;

[0156] (2) Post-processing the printed open channel structure printing nozzle, including:

[0157] 1) Remove the support structure generated by printing on the nozzle;

[0158] 2) Soak the nozzle in anhydrous ethanol and clean it ultrasonically for 6 minutes;

[0159] 3) Blow dry the nozzle and perform secondary curing on the nozzle;

[0160] (3) drying the Fe3O4 magnetic nanoparticles;

[0161] (4) using bisphenol A epoxy resin, Fe3O4 magnetic nanoparticles, dimethyl sulfoxide solvent, hydrophobic silane and polyvinyl pyrrolidone to prepare a magnetic particle-reinforced epoxy resin slurry with uniform properties;

[0162] (5) filling the magnetic particle reinforced epoxy resin slurry into a barrel and installing it in a slurry direct writing printing device;

[0163] (6) Install the outer flow channel printing nozzle to the bottom of the barrel;

[0164] (7) Starting printing, applying driving force to drive the magnetic slurry to be extruded from the barrel into the nozzle cavity;

[0165] (8) The magnetic particle-reinforced epoxy resin slurry is driven by the driving force to flow out of the nozzle cavity, flow on the outer wall of the nozzle head, form a thin film flow, and converge at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then gradually prints the sample according to the preset program;

[0166] (9) The printed magnetic device samples are placed in a constant temperature box for heating and curing to ensure that the epoxy resin is fully cross-linked and the magnetic particles are fixed in the resin matrix.

[0167] During the printing process, due to the large outlet area of ​​the cavity, only 5kPa of air pressure is required to smoothly extrude the magnetic particle slurry. After the magnetic particle slurry is driven by the driving force to flow out of the nozzle cavity, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0168] Example 6

[0169] Combined with fused deposition technology to print glass, the specific type of glass is high borate glass. The steps are:

[0170] (1) An open channel structure printing nozzle made of stainless steel is prepared by metal machining. The structure is as follows Figure 1 As shown;

[0171] (2) Post-processing the processed open channel structure printing nozzle, including:

[0172] 1) Clean the oil residue on the nozzle during processing;

[0173] 2) Polish and grind the processed products to improve their surface smoothness and glossiness;

[0174] (3) crushing bulk glass material into granular material by extrusion or manual grinding;

[0175] (4) Use a vibrating screen to screen the crushed granular material and collect particles ranging from a few millimeters to several millimeters in size as printing consumables.

[0176] (5) Filling the glass consumables into the heating component and installing it in the fused deposition printing device;

[0177] (6) Install the outer flow channel printing nozzle to the bottom of the heating component;

[0178] (7) heating the glass to the melting point of the material so that the molten glass reaches a suitable viscosity;

[0179] (8) starting printing, using gravity as a driving force to squeeze the molten glass from the heating component into the nozzle cavity;

[0180] (9) After the cavity is full, the molten glass breaks through the surface tension and overflows from the nozzle cavity, flowing on the outer wall of the nozzle head to form a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then gradually prints the sample according to the preset program;

[0181] (10) Annealing the liquid glass from the outflow of the heating component to the entire molding process, and annealing the entire printing process,

[0182] (11) The final molded sample is slowly cooled to room temperature and finally taken out.

[0183] During the printing process, under the action of gravity, the glass slurry can flow out smoothly by simply adjusting the outlet area. After the glass slurry flows out of the nozzle cavity driven by the volume force, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0184] Example 7

[0185] Combined with fused deposition technology to print multi-primary element alloys, specifically NiFeCrCo. The steps are:

[0186] (1) An open channel structure printing nozzle made of alumina is prepared by ceramic machining. The structure is as follows Figure 1 As shown;

[0187] (2) Post-processing the processed open channel structure printing nozzle, including:

[0188] 1) Clean the oil residue on the nozzle during processing;

[0189] 2) Polish and grind the processed products to improve their surface smoothness and glossiness;

[0190] (3) crushing the alloy material into particles by grinding;

[0191] (4) Use a vibrating screen to screen the crushed granular material and collect particles ranging from a few millimeters to several millimeters in size as printing consumables.

[0192] (5) Filling the alloy consumables into the heating component and installing it in the fused deposition printing device;

[0193] (6) Install the outer flow channel printing nozzle to the bottom of the heating component;

[0194] (7) The alloy is uniformly heated to the melting point of the material so that the molten metal reaches a suitable viscosity;

[0195] (8) printing begins, with gravity acting as a driving force to squeeze the molten metal material out of the heating component into the nozzle cavity;

[0196] (9) After the cavity is full, the molten alloy breaks through the surface tension, overflows from the nozzle cavity, flows on the outer wall of the nozzle head, forms a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then gradually prints the sample according to the preset program;

[0197] (10) Annealing the liquid alloy from the outflow of the heating component to the entire molding process, and annealing the entire printing process.

[0198] (11) The final molded sample is slowly cooled to room temperature and finally taken out.

[0199] During the printing process, under the action of gravity, the slurry can flow out smoothly by simply adjusting the outlet area. After the slurry flows out of the nozzle cavity driven by the volume force, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0200] Example 8

[0201] Combine fused deposition technology to print pure metal, the specific metal material is Cu. The steps are:

[0202] (1) An open channel structure printing nozzle made of alumina is prepared by ceramic machining. The structure is as follows Figure 1 As shown;

[0203] (2) Post-processing the processed open channel structure printing nozzle, including:

[0204] 1) Clean the oil residue on the nozzle during processing;

[0205] 2) Polish and grind the processed products to improve their surface smoothness and glossiness;

[0206] (3) crushing the metal material into particles by grinding;

[0207] (4) Use a vibrating screen to screen the crushed granular material and collect particles ranging from a few millimeters to several millimeters in size as printing consumables.

[0208] (5) Filling the metal consumables into the heating component and installing it in the fused deposition printing device;

[0209] (6) Install the outer flow channel printing nozzle to the bottom of the heating component;

[0210] (7) The alloy is uniformly heated to the melting point of the material so that the molten metal reaches a suitable viscosity;

[0211] (8) printing begins, with gravity acting as a driving force to squeeze the molten metal material out of the heating component into the nozzle cavity;

[0212] (9) After the cavity is full, the molten metal breaks through the surface tension and overflows from the nozzle cavity, flowing on the outer wall of the nozzle head to form a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. The printer then gradually prints the sample according to the preset program;

[0213] (10) Annealing the liquid alloy from the outflow of the heating component to the entire molding process, and annealing the entire printing process.

[0214] (11) The final molded sample is slowly cooled to room temperature and finally taken out.

[0215] During the printing process, under the action of gravity, the pure copper slurry can flow out smoothly by simply adjusting the outlet area. After the pure copper slurry flows out of the nozzle cavity driven by the volume force, it flows on the outer wall of the nozzle head, forming a thin film flow, and converges at the end of the nozzle head to form a slurry liquid column flowing down and deposited on the printer substrate. During the long printing process, the printed lines are uniform and stable, and the nozzle will not be blocked. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0216] Example 9

[0217] Combine electrohydrodynamic printing technology to print a patternable pure copper micro-bump array, the steps are:

[0218] (1) A conical open channel structure printing nozzle made of pure tungsten is prepared by machining, the structure is as follows Figure 1 As shown;

[0219] (2) Post-processing the processed conical open channel structure printing nozzle, including:

[0220] 1) Clean the oil residue on the nozzle during processing;

[0221] 2) Polish and grind the processed products to improve their surface smoothness and glossiness;

[0222] (3) The nozzle is fixed in the coil, the metal copper tube is sleeved on the outside of the nozzle, and continuous wire feeding is achieved through the wire feeding mechanism;

[0223] (4) Argon gas is introduced into the molding cavity to form a low-oxygen atmosphere (oxygen concentration is less than 0.1%).

[0224] (5) Start printing, apply alternating current in the induction coil, heat the copper tube to a molten state, and form a uniform liquid film on the nozzle surface;

[0225] (6) A high voltage electric field (greater than 5 kV) is applied between the nozzle and the substrate, and the molten copper forms a Taylor cone at the bottom of the outer flow channel nozzle;

[0226] (7) Using a square wave signal to modulate the voltage, the cone is induced to break through the surface tension and spray at the tip of the cone, depositing copper droplets with a diameter of 50 μm at a stable frequency;

[0227] (8) Control the movement of the substrate to ultimately achieve patterned deposition of a pure copper micro-bump array.

[0228] During the printing process, the copper droplets form a liquid film on the external flow channel nozzle, and the electric field force forms a Taylor cone structure at the top of the nozzle. When the charge accumulates to a sufficient degree, the copper droplets break through the surface tension and are ejected at a set frequency, forming uniform copper droplets on the substrate. The size of the copper droplets is much smaller than that of the copper droplets printed by ordinary internal flow channel needles. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0229] Example 10

[0230] Combined with electrohydrodynamic printing technology to print high viscosity thermoplastic polymers, the steps are:

[0231] (1) A conical open channel structure printing nozzle made of pure tungsten is prepared by machining, the structure is as follows Figure 1 As shown;

[0232] (2) Post-processing the processed conical open channel structure printing nozzle, including:

[0233] 1) Clean the oil residue on the nozzle during processing;

[0234] 2) Polish and grind the processed products to improve their surface smoothness and glossiness;

[0235] (3) The nozzle is fixed in the coil, the thermoplastic polymer tube is sleeved on the outside of the nozzle, and continuous wire feeding is achieved through a wire feeding mechanism;

[0236] (4) Start printing, apply alternating current in the induction coil, heat the tungsten nozzle to a relatively low temperature (greater than 300°C), the polymer is continuously melted near the bottom of the nozzle by the heat, and forms a continuous and uniform liquid film on the surface of the nozzle;

[0237] (5) A high voltage electric field (greater than 2 kV) is applied between the nozzle and the substrate, and the molten polymer forms a Taylor cone at the bottom of the outer flow channel nozzle;

[0238] (6) Using a constant voltage electric field, the molten polymer is induced to break through the surface tension, forming a continuous and uniform molten polymer filament (10 μm in diameter) at the bottom of the cone and deposited on the printer substrate. The printer then gradually prints the sample according to the preset program.

[0239] During the printing process, the highly viscous thermoplastic polymer droplets form a liquid film on the external flow channel nozzle, and the electric field force forms a Taylor cone structure at the top of the nozzle. When the charge accumulates to a sufficient degree, the highly viscous thermoplastic polymer droplets break through the surface tension and are ejected at a set frequency, forming uniform droplets on the substrate. The droplet size is much smaller than the droplet size printed by the ordinary internal flow channel needle. After printing, the nozzle is easy to clean and can be used for secondary printing.

[0240] The present invention has been described in detail above in conjunction with the embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A 3D printing method, characterized in that: The method comprises the steps of liquid material flowing through an open flow channel, being guided, converged and then solidified into a shape. During the process of the liquid material flowing through the open flow channel, the liquid material forms a thin film flow on the surface of the open flow channel.

2. The 3D printing method according to claim 1, characterized in that: When the liquid material flows through the open flow channel, the flow velocity of the liquid material gradually increases along the radial direction from the inner side close to the flow channel wall surface to the outer side far from the flow channel wall surface.

3. The 3D printing method according to claim 1 or 2, characterized in that: The 3D printing method also includes the steps of the liquid material flowing through the open flow channel, being guided and converged, forming a liquid column or breaking into droplets at the tail end of the open flow channel, and flowing down in the direction of gravity to be deposited and solidified on the substrate.

4. A flow channel structure for implementing the 3D printing method according to any one of claims 1 to 3, characterized in that: The cross section of the flow channel structure is an open pattern.

5. The flow channel structure according to claim 4, characterized in that: From the upstream direction to the downstream direction of the flow of the liquid material, the cross-sectional area of ​​the flow channel structure gradually decreases.

6. The flow channel structure according to claim 4, characterized in that: The material of the flow channel structure includes at least one of resin, stainless steel, aluminum oxide and tungsten.

7. The flow channel structure according to claim 4, characterized in that: The tail end of the flow channel structure is in the shape of a Taylor cone.

8. The flow channel structure according to any one of claims 4 to 7, characterized in that: From the direction of liquid material flow, the flow channel structure includes a cavity and a nozzle.

9. The flow channel structure according to claim 8, characterized in that: The head end of the cavity is provided with a Luer connector or a threaded structure.

10. A 3D printing device, characterized in that: The flow channel structure comprises the flow channel structure as claimed in any one of claims 4 to 9.

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