CN108568966A - Integrated nozzle for electric field driven injection of multi-material 3D printing - Google Patents

Abstract

The invention discloses an integrated spray head for multi-material 3D printing driven by an electric field. By separating the material mixing function and the feeding function, the multi-material mixing is more sufficient and uniform, ensuring that the materials are completely mixed and uniform. Jet printing; the integration of the nozzle and the ring-shaped extraction electrode is realized, that is, the print nozzle is self-contained. Using the cone jet mode, higher-resolution dots and lines can be printed. The technical solution is: including the print nozzle, the top of the print nozzle and the feeding Module connection, the feeding module is connected with the mixing module; the mixing module includes a mixing barrel, and the feeding pipeline is set at the bottom of the mixing barrel to communicate with the feeding module; The motor is connected; the printing nozzle includes a conductive nozzle, which is fixed at the bottom of the injection cylinder, and a ring-shaped extraction electrode is arranged on the outer periphery of the conductive nozzle. The conductive nozzle is connected to the positive pole of the high-voltage pulse power supply, and the ring-shaped extraction electrode is grounded.

Description

An integrated nozzle for electric field-driven jetting multi-material 3D printing

technical field

The invention relates to the technical fields of additive manufacturing and multi-material 3D printing, in particular to an integrated spray head for electric field-driven ejection of multi-material 3D printing.

Background technique

With the rapid development of science and technology, the lightweight production of large structural parts, high-precision manufacturing of flexible electronic products and other fields have put forward stricter and more requirements on the performance of materials. Due to their excellent performance, composite materials It has been widely used in various industries. As an emerging additive manufacturing method, 3D printing is also used to research and manufacture composite materials. Therefore, existing 3D printers should have the following capabilities: realize active mixing of multiple materials, enhance material physics, mechanical and other properties; prepare multifunctional gradient materials, and can accurately and uninterruptedly switch between various functional materials; realize high-precision, high-efficiency, high-resolution printing, etc.

The existing multi-material electrojet printing 3D printing methods include multi-nozzle scheme and screw stirring scheme, but there are many shortcomings and limitations based on these two schemes. For example, based on the multi-nozzle scheme, there are: (1) The multi-nozzle structure is complex and the equipment cost is high; (2) The nozzles need to be switched frequently, and the printing efficiency is low; (3) Multi-material active mixing cannot be realized; (4) It is limited by the nozzle configuration The quantity is limited, and the number of types of materials that can be printed at one time is limited. In addition, multi-material forming nozzles generally use multiple nozzles installed in parallel at the same height, and each nozzle can process one material. Generally, only one nozzle is working during the printing process, and other nozzles that are on standby at the same height may have problems with the construction. Interference with the tissue forming surface. Based on the screw stirring scheme, there are: (5) The integrated design of the mixing chamber and the printing head leads to insufficient mixing of multiple materials and poor functionality of the printed structural parts; (6) The mixed materials cannot be replenished in time during the printing process, resulting in low printing efficiency. Therefore, the existing multi-material electrojet printing 3D printing technology is difficult to achieve stable and efficient integrated manufacturing of multi-material and multi-scale structures.

Electro hydrodynamic jet printing (Electro hydrodynamic Jet Printing, E-jet) is a technology based on electrohydrodynamic (EHD) micro-droplet jet deposition, which is different from traditional jet printing technologies (thermal jet printing, piezoelectric jet printing, etc.) Different from the "push" method, EHD jet printing uses electric field drive to generate a very fine jet from the top of the liquid cone (Taylor cone) in a "pull" manner. The printing resolution is not limited by the diameter of the nozzle, and it can realize the manufacture of complex three-dimensional micro-nano structures with sub-micron and nano-scale resolution on the premise that the nozzle is not easy to clog. And the range of materials that can be used for electrojet printing is very wide. Therefore, compared with the existing 3D printing technology, the electrojet printing technology has the characteristics of good material compatibility (wide range of applicable materials, especially many high-viscosity materials) and high resolution. Deficiencies and limitations: (1) The printing height is limited; (2) Conformal printing cannot be realized; (3) The receiving substrate material is limited; (4) Pneumatic feeding cannot achieve precise control of the liquid output.

Therefore, in order to overcome the shortcomings and defects of the existing multi-material electrojet printing 3D printing in the integrated manufacturing of multi-material, macro/micro/nano multi-scale structures, and realize the integration of "function-driven structure, material, performance design and manufacturing" "Seamless integration" combines design elements such as materials, microstructures, and macrostructures with functional requirements to achieve shape-controlled and controlled manufacturing of complex organizational structures (especially through multi-material and microstructure layout improvements to optimize product performance, increase New functions), to meet the actual needs of new material development, biomedical, electronic products, tissue engineering, MEMS, wearable electronic devices, 4D printing and other research and development and large-scale production, there is an urgent need to develop new multi-material, multi-scale 3D printing craft and equipment.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides an integrated nozzle for multi-material 3D printing driven by an electric field. By separating the mixing function and the feeding function, the multi-material mixing is more sufficient and uniform, ensuring The material is jet printed under the premise of complete mixing and uniformity; the integration of the nozzle and the annular extraction electrode is realized, that is, the printing nozzle is self-contained, and the cone jet mode can be used to print higher-resolution points and lines; it realizes multi-material, The high-precision, high-efficiency, stable, and integrated manufacturing of multi-scale structures improves the shape and controllability of 3D printing.

The specific implementation method of the present invention is: (1) integrating the material mixing module, the material feeding module and the print head module. Specifically, the mixing module and the feeding module are separated, and the two are connected through a feeding pipeline, and the printing nozzle module is directly installed at the bottom (lower part) of the feeding module. Among them, the mixing module realizes efficient and uniform mixing of various printing materials. The mixing module is provided with multiple feeding ports for providing one or more different printing materials to the mixing module. The mixing mechanism is driven by the motor to achieve uniform mixing of various printing materials, and the uniform The material is conveyed to the feeding module. The feeding module realizes stable delivery and quantitative injection of printing materials. On the one hand, the stepper motor is used to control the uniform rotation of the screw to provide stable back pressure to realize the uniform supply of printing materials. Precise control of liquid output. The feeding module transports the material to the printing nozzle under the action of the screw; the printing nozzle module realizes the jet deposition of the printing material under the action of the electric field. (2) The printing nozzle module is self-contained and connected to the high-voltage pulse power supply through the connecting wire. The print nozzle module is composed of a conductive nozzle and a ring-shaped extraction electrode, and the relative position between the two is precisely adjustable and coaxial. The annular extraction electrode is connected to the negative pole of the high-voltage power supply, and the conductive nozzle is connected to the positive pole of the high-voltage power supply. The strong electric field force between the conductive nozzle and the annular extraction electrode is used to realize the spray deposition of materials. (3) Set two printing modes, macro-scale and micro-scale. In the macro printing mode, the screw is used to rotate and extrude the printing material. In the micro printing mode, the cone jet formed by the electric field force is used to print, realizing macro, micro and nano Cross/multi-scale integrated manufacturing.

Further, the present invention adopts the following technical solutions:

An integrated nozzle for multi-material 3D printing driven by electric field, including a printing nozzle, the top of the printing nozzle is connected to a feeding module, and the feeding module is connected to a mixing module;

The mixing module includes a mixing cylinder, and a feeding pipeline is arranged at the bottom of the mixing cylinder to communicate with the feeding module;

The feeding module includes an injection cylinder, a screw is arranged in the injection cylinder, and the top of the screw is connected with a stepping motor;

The printing nozzle includes a conductive nozzle, which is fixed on the bottom of the injection cylinder, and a ring-shaped extraction electrode is arranged on the outer periphery of the conductive nozzle. The conductive nozzle is connected to the positive pole of the high-voltage pulse power supply, and the ring-shaped extraction electrode is grounded.

Further, an opening is provided on the side of the syringe, and a quick feed joint is provided at the opening, and the quick feed joint is connected to the feed pipeline.

Further, the ring-shaped extraction electrode is fixed on the ring-shaped extraction electrode holder, and the ring-shaped extraction electrode holder is connected to the outer wall of the syringe.

Further, a plurality of feeding ports are arranged above the side of the mixing cylinder.

Further, an air quick connector is provided on the top of the mixing barrel, and the air quick connector communicates with the air pressure pipeline.

Alternatively, an air quick joint is arranged above the side of the mixing cylinder, and the air quick joint communicates with the air pressure pipeline.

Further, a stirring shaft is arranged in the mixing barrel, and the top of the stirring shaft is connected with a stirring motor.

Further, the diameter of the stirring shaft is smaller than the inner diameter of the mixing cylinder.

Further, a spiral groove is provided on the side wall of the stirring shaft.

Further, the mixing module is fixed on the installation base plate by a clamp.

Further, the injection barrel and the mixing barrel are provided with a waste liquid collection pipeline, the waste liquid collection pipeline is built with an integrated pump, and the waste liquid collection pipeline is also connected with the vacuum pipeline.

Compared with prior art, the beneficial effect of the present invention is:

(1) Realize the active mixing of multiple materials. Multiple feeding ports are set on the mixing module, and each feeding port can input materials with different proportions. The stirring shaft is controlled by the stirring motor to stir various printing materials in the barrel according to the set speed, realizing multiple printing materials. Materials mix quickly, with the potential to print functionally graded parts.

(2) Realize high-precision mixing of materials, precisely control nozzle flow, and print structures with strong functionality and high reliability. First, the feeding module and the mixing module are separated to ensure that the material is fully mixed and evenly fed into the injection cylinder for printing. This ensures that the material used for jet deposition is completely mixed and uniform, and the unmixed material is excluded. Impact. Secondly, the precise control of back pressure increment and liquid flow can be achieved by controlling the screw speed, that is, adjusting the screw speed can control the liquid output of the nozzle, and the screw rotates at a constant speed to establish a steadily increasing back pressure to achieve stable delivery of printing materials. The amount of material can be set at different rotation speeds to precisely control the flow rate of the nozzle. The combined use of the stirring device and the feeding module ensures the function of the printed structure and improves the reliability of the printed structure.

(3) The printing nozzle, feeding module and mixing module are integrated and installed on the fixed base plate. The integrated nozzle device has strong portability and good practicability, and can be transplanted to any form of workbench (three-axis or five-axis) axis) for printing.

(4) High-efficiency printing of any material ratio can be realized. The mixing module and the feeding module are separated, and the mixing and feeding functions do not affect each other, which can realize continuous and sufficient material supply, and solve the problem that the integrated screw mixing device cannot supply materials in time, mixing and printing cannot be carried out at the same time, and the printing efficiency is low.

(5) The process has a wide range of applications, good material compatibility and conformal printing can be realized. The ring-shaped extraction electrode is introduced as the negative electrode grounding, and the conductive nozzle is connected to the positive electrode of the high-voltage power supply. The electric field force formed between the two is not affected by the printing height, which overcomes the limitations of traditional electrojet printing in printing height, printing substrate material and shape, etc. Limits, can achieve accurate printing of the microstructure of objects, and at the same time realize printing on conformal surfaces. The use of electrojet printing solves the problem of printing high-viscosity materials and reactive materials (such as AB epoxy resin glue), and can print various high-viscosity liquid materials such as biological materials, metal nanoparticles, ceramic materials, organic functional materials, etc. The integrated printing of liquid and nanomaterials has greatly expanded the application field of the process.

(6) Integrated printing of macro/micro cross-scale structures. It has both macro-scale and micro-scale printing modes. During the printing process, the two modes can be switched arbitrarily in the same component, and the printing of components can be completed as needed, realizing the macro and micro multi-scale printing of objects.

(7) The device adopts the form of single nozzle and multiple feed ports, which is simple in structure, convenient in operation, low in cost, and does not need to switch printing nozzles frequently during the working process. Problems, overcome the defects and deficiencies of the existing multi-nozzle head printing.

The invention can realize multi-material technology, macro/micro/nano multi-scale structure integrated design, and can be used in new material development, biomedicine, tissue engineering, MEMS, wearable electronic equipment, aerospace, 3D functional structure electronics, new energy ( Fuel cells, solar energy, etc.), high-definition display, micro-nano optical devices, soft robots and many other fields and industries.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application, and do not constitute improper limitations to the present application.

Fig. 1 is a schematic diagram of the structure of an integrated nozzle for electric field-driven jet multi-material 3D printing according to the present invention.

Fig. 2 is a schematic cross-sectional view of the integrated nozzle according to Embodiment 1 of the present invention.

Fig. 3 is a schematic cross-sectional view of the integrated nozzle according to Embodiment 2 of the present invention.

In the figure, 1 printing nozzle, 101 conductive nozzle, 102 annular extraction electrode, 103 annular extraction electrode fixing frame, 2 feeding module, 201 injection barrel, 202 screw, 203 feeding quick connector, 204 stepping motor, 3 mixing module, 301 feed pipeline, 302 stirring shaft, 303 mixing barrel, 304A material inlet, 305B material inlet, 306 stirring motor, 307 gas quick connector, 4 clamps, 5 installation base plate.

Detailed ways

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

As introduced in the background technology, there are deficiencies in the prior art. In order to solve the above technical problems, the present application proposes an integrated nozzle for electric field driven multi-material 3D printing.

Example 1:

Figure 1 is a schematic diagram of an integrated nozzle for electric field-driven jetting multi-material 3D printing. It includes a print nozzle 1, a feeding module 2, a mixing module 3, a fixture 4, and a mounting base 5. Among them, the printing nozzle 1 is installed at the bottom of the feeding module 2, and the side of the feeding module 2 is provided with a quick connector for feeding and connected to the mixing module 3 through the feeding pipeline 301. The mixing module 3 is fixed on the fixture 4, and the printing nozzle 1 , the feeding module 2 and the mixing module 3 are uniformly fixed on the installation base plate 5, and can be installed on any form of three-axis or five-axis workbench for printing as required.

Fig. 2 is a schematic cross-sectional view of Embodiment 1 of the present invention. It includes a conductive nozzle 101, an annular extraction electrode 102, an annular extraction electrode holder 103, an injection cylinder 201, a screw 202, a feeding quick connector 203, a stepping motor 204, a feeding pipeline 301, a stirring shaft 302, and a mixing cylinder 303 , A material feed port 304, B material feed port 305, stirring motor 306, gas quick connector 307, fixture 4, installation base plate 5. The conductive nozzle 101, the annular extraction electrode 102, and the annular extraction electrode fixing frame 103 together form the printing nozzle 1, and the annular extraction electrode 102 is provided with the outer periphery of the conductive nozzle 101; the injection cylinder 201, the screw 202, the quick feed connector 203, and the stepping motor 204 are jointly composed The feeding module 2; the feeding pipeline 301, the stirring shaft 302, the mixing cylinder 303, the feeding port, the stirring motor 306, and the air quick connector 307 together form the mixing module 3, which is connected to the air pressure pipeline through the air quick connector 307 . In this application, there are two feed ports, which are feed port 304 for material A and feed port 305 for material B, respectively, to transport material A and material B into the mixing barrel respectively.

The conductive nozzle 101 is a metal nozzle or a nozzle coated with a conductive material, and the inner diameter of the nozzle is 1-1000 microns; in this embodiment, the conductive nozzle adopts a stainless steel needle, the specification is 25G, the inner diameter is 0.26mm, and the outer diameter is 0.5mm. The lowermost end of the syringe 201 is connected to the positive pole of the high-voltage pulse power supply through a wire.

The annular extraction electrode 102 adopts a copper sheet with excellent electrical conductivity, the inner diameter of the annular extraction electrode is 0.1-10 mm, the outer diameter is 1-20 mm, and the thickness is 1-200 microns; the inner diameter of the annular extraction electrode in this embodiment is 8mm, and the outer diameter is 18mm, thickness 100μm, installed on the lower surface of the annular extraction electrode fixing frame 103 and installed on the injection cylinder of the feeding module through threaded connection, the upper and lower positions of the annular extraction electrode can be adjusted to ensure that the conductive nozzle and the annular extraction electrode are coaxial. Different positional relationships between the annular extraction electrode and the nozzle will form different electric field distributions, and the upper and lower positions of the two are determined according to actual needs. The ring extraction electrode is grounded through a wire.

The annular extraction electrode holder 103 is a plastic cylinder with internal threads, its inner diameter is the same as the outer diameter of the injection barrel 201, and the outer diameter is the same as the outer diameter of the annular extraction electrode 102, and is fixed on the injection barrel 201 by threaded connection, and Adjustable up and down position.

The conductive nozzle 101 is coaxial with the annular extraction electrode 102. By adjusting the upper and lower positions of the annular extraction electrode fixing frame 103, the bottom end of the conductive nozzle 101 passes through the annular extraction electrode 102 and protrudes a distance of 4 mm.

The injection barrel 201 is made of insulating material to prevent it from being connected to the conductive nozzle. In this embodiment, a plastic syringe is used to prevent conduction with the conductive nozzle 101 from affecting other electronic components of the device.

The stepping motor 204 drives the screw 202 to rotate in the injection barrel 201, and the printing material is delivered to the conductive nozzle 101 through the extrusion of the screw 202. The feeding quick joint 203 is installed on the side of the injection barrel 201 and connected to the feeding pipeline 301 . The diameter of the screw 202 is slightly smaller than the inner diameter of the injection barrel 201 , so as to avoid mutual abrasion between the screw 202 and the injection barrel 201 due to too small a gap.

The stepper motor 204 and the stirring motor 306 are 42 planetary deceleration stepper motors with large torque and a speed range of 10r/min-200r/min.

The feeding pipeline 301 is a black Teflon tube, and the two ends of the pipeline are respectively connected with the mixing cylinder 303 and the quick connector 203 for feeding.

The stirring motor 306 drives the stirring shaft 302 to rotate to realize the stirring of the material. The diameter of the stirring shaft 302 is smaller than the inner diameter of the mixing barrel 303, leaving enough space for stirring the materials.

The mixing barrel 303 is made of insulating material, and the printing material is contained in the mixing barrel 303 , and the material is supplied to the feeding module through the feeding pipeline 301 . The feeding port of the mixing barrel can be provided with multiple, and each feeding port is connected with a micro-injection pump. One end of the gas circuit quick connector is connected with the air pressure pipeline, and the other end is connected with the mixing cylinder to provide dynamic driving force for the material flow.

The material A feed port 304 and the material B feed port 305 are respectively installed on both sides of the mixing module 3 , and during the printing process, different printing materials can be switched and supplied according to needs to realize multi-material printing. The feed port can be connected with the material injection pump to realize the input of materials on time and in quantity. The air quick joint 307 is installed above the mixing cylinder 303 through threaded connection, and is connected with the air pressure pipeline.

The feeding module 2 and the mixing module 3 can be provided with a waste liquid collector, the waste liquid collector is a waste liquid collection pipeline with a built-in integrated pump, and the vacuum pressure in the waste liquid collector is -500mbar. One end of the waste liquid collection line is set inside the mixing barrel and injection barrel, and the other end is connected to the vacuum line, which is used to recover the residual material in the nozzle through vacuum negative pressure. When changing materials, open the waste liquid collector and turn the device Residual printing materials inside are recycled to the waste liquid collector, which is convenient for quick multi-material replacement, and realizes seamless and precise transition between flexible materials and rigid materials.

During the printing process using the spray head of this application, the stirring motor 306 drives the stirring shaft 302 to rotate, and the side wall of the stirring shaft 302 is provided with a spiral groove to stir the printing materials until the materials are completely mixed, and the uniformly mixed materials are quickly conveyed through the feeding pipeline 301 to the syringe 201, the printing material in the syringe 201 moves downward under the back pressure of the screw 202 and flows out from the conductive nozzle 101, because a certain pulse high voltage is applied between the conductive nozzle 101 and the ring-shaped extraction electrode 102 , the generated electric field force pulls the printing material out of the nozzle and sprays it onto the surface of the receiving substrate.

Example 2:

Fig. 3 is a schematic cross-sectional view of Embodiment 2 of the present invention. On the basis of the integrated spray head in the above-mentioned embodiment 1, the stirring shaft 302 is removed, and the quick joint of the gas path is arranged on the top of the mixing cylinder. The material A feed port 304 and the material B feed port 305 can be switched to supply different printing materials according to needs during the printing process, so as to realize multi-material printing. Moreover, the addition of a feed port allows timely replenishment of printing materials into the mixing barrel 303 without frequent switching of multiple nozzles, making the operation simpler and more convenient.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, various modifications and changes may be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. An integrated nozzle for electric field-driven jet multi-material 3D printing, characterized in that it includes a printing nozzle, the top of the printing nozzle is connected to a feeding module, and the feeding module is connected to a mixing module; The mixing module includes a mixing cylinder, and a feeding pipeline is arranged at the bottom of the mixing cylinder to communicate with the feeding module; The feeding module includes an injection cylinder, a screw is arranged in the injection cylinder, and the top of the screw is connected with a stepping motor; The printing nozzle includes a conductive nozzle, which is fixed on the bottom of the injection cylinder, and a ring-shaped extraction electrode is arranged on the outer periphery of the conductive nozzle. The conductive nozzle is connected to the positive pole of the high-voltage pulse power supply, and the ring-shaped extraction electrode is grounded. 2. The integrated nozzle according to claim 1, wherein an opening is provided on the side of the injection cylinder, a quick feed joint is provided at the opening, and the quick feed joint is connected to the feed pipeline. 3 . The integrated spray head according to claim 1 , wherein the annular extraction electrode is fixed on the annular extraction electrode fixing frame, and the annular extraction electrode fixing frame is connected to the outer wall of the syringe. 4 . 4. The integrated spray head according to claim 1, characterized in that, a plurality of feeding ports are arranged above the side part of the mixing cylinder. 5. The integrated spray head according to claim 1, characterized in that, the top of the mixing barrel is provided with an air quick joint, and the air quick joint communicates with the air pressure pipeline. 6. The integrated spray head according to claim 1, characterized in that, an air quick joint is arranged above the side of the mixing cylinder, and the air quick joint communicates with the air pressure pipeline. 7. The integrated spray head according to claim 1 or 6, characterized in that, a stirring shaft is arranged in the mixing barrel, and the top of the stirring shaft is connected to a stirring motor. 8. The integrated spray head according to claim 7, wherein the diameter of the stirring shaft is smaller than the inner diameter of the mixing cylinder. 9. The integrated spray head according to claim 7, characterized in that, the side wall of the stirring shaft is provided with a spiral groove. 10. The integrated spray head according to claim 1, characterized in that, the mixing module is fixed on the installation base plate by a clamp; waste liquid collection pipelines are arranged in the injection barrel and the mixing barrel, and the waste liquid collection pipelines Built-in integrated pump, the waste liquid collection line is also connected with the vacuum line.