阅读说明：本技术 一种基于直写式多材料复合3d打印系统及方法 (Direct-writing-based multi-material composite 3D printing system and method ) 是由 张计锋 殷志富 杨雪 周雪莉 贾炳强 胡伟 李露 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种基于直写式多材料复合3D打印系统及方法,包括：3D打印模块,用于制造多材料复合产品；材料供应系统,用于不同材料不同比例实时供应；气泵系统,用于材料供应过程中的动力提供；计算机控制系统,通过控制软件控制各个系统有序配合工作,实现多材料复合打印产品按既定工艺完成。本发明可实现直写式打印中单一通道内任意几何截面多材料复合式打印成型。此外,本发明提出的可控变径旋转成型轴,可根据预先设计动态调控各段成型轴的直径,从而实现无支撑对称结构的高效立体成型,在生物医疗及工程领域具有重大应用潜力。(The invention discloses a direct-writing-based multi-material composite 3D printing system and a method, which comprises the following steps: the 3D printing module is used for manufacturing a multi-material composite product; the material supply system is used for supplying different materials in different proportions in real time; the air pump system is used for providing power in the material supply process; and the computer control system controls all the systems to work in an orderly and matched manner through control software, so that the multi-material composite printing product is finished according to a set process. The invention can realize the multi-material composite printing molding of any geometric section in a single channel in the direct-writing printing. In addition, the diameter of each section of the forming shaft can be dynamically regulated and controlled according to the pre-design, so that the high-efficiency three-dimensional forming of the unsupported symmetrical structure is realized, and the controllable variable-diameter rotary forming shaft has great application potential in the fields of biological medicine and engineering.)

1. A multi-material composite 3D printing system and method based on direct writing is characterized by comprising the following steps:

the 3D printing module (1) is used for generating a 3D printing component by controlling the multi-material composite printing nozzle to move in a three-dimensional space, so that the multi-material composite printing function is realized;

a material supply system (2) for storing different printing materials and for real-time supply of the multi-material for the 3D printing module (1);

the air pump system (3) is used for supplying air pressure to the material supply system (2) and the 3D printing module (1) and controlling the extrusion amount and the extrusion speed of various materials in the 3D printing process;

the computer control system (4) is used for controlling the operation of the whole multi-material direct-writing type 3D printing system, firstly, the air pump system (3) is controlled to deliver stable air pressure to the material supply system (2) and the 3D printing module (1), so that the material supply system (2) can deliver materials to the 3D printing module (1) according to a set proportion, and then the composite printing of multiple materials of the system is realized by controlling the motion track of the three-dimensional motion system (15) and the multi-material extrusion speed of the 3D printing nozzle (11).

2. The direct-write multi-material composite 3D printing system and method according to claim 1, wherein the 3D printing module further comprises:

the 3D printing nozzle (11) can move freely in a three-dimensional space along with the three-dimensional motion system (15), the 3D printing nozzle (11) can realize real-time variable-speed motion in the printing process, and the speed range is 0.1-5000 mm/s;

the temperature of a material output by the 3D printing nozzle (11) is controlled by a temperature control module (16);

wherein a thin-wall inner core structure (112) is arranged in the 3D printing nozzle (11);

the thin-wall inner core structure (112) is arranged and combined in any geometric structure such as a triangle, a circle, a square and a diamond;

the thin-wall inner core structure (112) can separate the material A (111) from the material B (113), so that each material system can independently exist in the 3D printing spray head (11);

the printing fixing device (12) is used for fixedly supporting all structures in the 3D printing module (1) and ensuring the stability of the system;

a 3D printing platform (14) for supporting the printing member (13) and ensuring the accuracy of its relative position;

the 3D printing platform (14) can be a two-dimensional forming substrate and can also be a controllable reducing rotary forming shaft;

the controllable variable-diameter rotary forming shaft is composed of an outer layer integral telescopic rubber film (141), a plurality of sectional telescopic variable-diameter cylinder structures (142), an independent hydraulic pushing device (143) and a forming fixing device (144);

the controllable variable-diameter rotary forming shaft is formed by combining a plurality of sectional telescopic variable-diameter cylinder structures (142), and the axial diameter of each sectional telescopic variable-diameter cylinder structure (142) can be changed in advance according to forming requirements, so that the forming of a variable-diameter symmetrical structure is realized;

the controllable variable-diameter rotary forming shaft can change the radial length of each section of sectional telescopic variable-diameter cylinder structure (142) according to the forming requirement, so that the forming appearance of a forming sample piece is optimized and adjusted;

the controllable reducing rotary forming shaft can integrally rotate clockwise or anticlockwise at variable speed along the axial direction, and the rotating speed range is 6 r/min-600 r/min;

wherein the radius of the telescopic reducing cylinder structure is determined by the pressure of an independent hydraulic pushing device (143);

wherein the independent hydraulic pushing device (143) can also be converted into mechanical pushing or pneumatic pushing;

the outer layer integral telescopic rubber membrane (141) is made of a rubber material with a large telescopic ratio, and integrally wraps the controllable reducing rotary forming shaft, and when the diameter of the telescopic reducing cylinder structure changes, the shape of the outer layer integral telescopic rubber membrane can also change along with the shape;

the three-dimensional motion system (15) controls the 3D printing nozzle (11) to move randomly in a three-dimensional space;

the heating module (16) is used for controlling the heating temperature of each material in the 3D printing nozzle (11) so that the material can flow smoothly in the nozzle;

the material combination conveying pipeline (17) is used for connecting the 3D printing spray head (11) and the combined material receiving module (19);

the material combination transmission pipeline (17) is mechanically designed, different materials are separated by a physical structure, and the material combination transmission pipeline (17) can move randomly in space along with the 3D printing nozzle (11);

the combined material receiving module (19) is fixed on the combined material receiving module fixing device (18) and is connected with the material supply system (2) and the air pump system (3);

the combined material receiving module (19) is directly connected with the material supply system (2), can receive different material systems from the material supply system (2), and then is conveyed to the 3D printing spray head (11) through different channels of the material combined conveying pipeline (17);

wherein each material system in the combined material receiving module (19) can independently control the conveying speed of the related material system in the material combination conveying pipeline (17) through the air pump system (3), and each material system is independent from each other in the combined material receiving module (19) and separated through a mechanical structure.

3. The direct-write based multi-material composite 3D printing system and method according to claim 1, wherein the material supply system (2) comprises:

a material A storage tank (21), a material B storage tank (22) and a material C storage tank (23);

wherein, the material supply system (2) is directly connected with the air pump system (3) and the computer control system (4), and each material system of the material supply system (2) can be independently controlled and conveyed by the air pump system (3) and the computer control system (4);

wherein the material A storage tank (21) conveys the material A system to a material A inlet of the combined material receiving module (19) through a material A conveying device (24); ,

wherein the material B storage tank (22) conveys the material B system to a material B inlet of the combined material receiving module (19) through a material B conveying device (25);

wherein the material C storage tank (23) delivers the material C system to the material C inlet of the combined material receiving module (19) by the material C delivery device (26);

wherein, the material supply system (2) is composed of two or more material storage tanks, and the material system of each material storage tank can be different.

4. The direct-write based multi-material composite 3D printing system and method according to claim 1, wherein the air pump system (3) further comprises:

the signal control system (31) is used for receiving a control command of the computer control system and then controlling the pressure of each material through the air pressure output port (32);

wherein, the air pressure output port (32) is independently connected with each material conveying pipeline and is respectively controlled.

5. The direct-write based multi-material composite 3D printing system and method according to claim 1, wherein the computer control system (4) further comprises:

the computer control system (4) controls the output speed and the output sequence of each material of the material storage system by controlling the air pump system (3), and the materials are conveyed to the combined material receiving module (19) through a conveying pipeline;

the computer control system (4) controls a three-dimensional motion system (15) in the 3D printing module (1) to perform spatial three-dimensional motion according to a certain track through software;

the computer control system (4) can control the temperature control module (16) to control the temperature of the material.

6. A multi-material composite 3D printing method based on direct writing is characterized by comprising the following steps:

s101, selecting printing materials

A, B, C can be selected as printing materials, and three different material systems are used for direct-writing multi-material composite printing;

the A, B, C material system can be a single homogeneous material, or a blended material or a composite material formed by mixing a plurality of materials;

the single homogeneous material, the blending material and the matrix material in the composite material can be high molecular polymers such as acrylonitrile-butadiene-styrene plastics, polycarbonates, nylons, polycarbonate, acrylonitrile-butadiene-styrene copolymer and mixture, thermoplastic plastic materials, polysulfone materials and the like, photosensitive resins such as Somos Next materials, resin Somos 11122 materials, Somos 19120 materials, epoxy resins and the like, rubber materials and the like; the reinforcing material of the composite material can be metal particles, ceramic particles, carbon fibers, glass fibers, nylon fibers and the like;

the material A (111) is an outermost layer material of multiple materials of the sprayer, and mainly has the main function that the material B and the material C are completely coated on the inner side of the material A, and can be a melt/solution, colloid or suspension with certain rheological property and shape-preserving capability, or can be rapidly solidified and shape-preserved under certain solidification conditions of temperature, ultraviolet light, humidity and the like;

the material B (113) and the material C (114) are inner layer materials of the printing nozzle, and can be functional materials with the characteristics of electric conduction, heat conduction, enhancement and the like;

wherein, one of the B material (113) and the C material (114) can be a permanent liquid material, and the other material is coated on the outer side of the permanent liquid material;

wherein, the inner side of the material A can be compounded by more than one different materials, the final shape of each material is determined by the mechanical physical structure of the spray head, and the materials of all channels in the spray head are different;

s102, manufacturing a multi-material composite component, which specifically comprises the following steps:

step 1, constructing a three-dimensional model, establishing the three-dimensional model according to requirements, and then performing discretization on the model;

step 2, selecting materials, namely selecting the optimal printing materials and the optimal structural shape of the printing nozzle according to the performance requirements of the components and the printing process conditions;

step 3, movement programming of multi-material composite printing, and determining a movement code of the 3D printing module (1) and a control signal of the air pump system (3) by combining the actual situation of the multi-material composite component;

step 4, putting the materials into a feeding supply system (2), putting the material A (111), the material B (113) and the material C (114) into a material A storage tank (21), a material B storage tank (22) and a material C storage tank (23) respectively, and connecting a compressed air source into an A material output device (24), a B material output device (25) and a C material output device (26) through an air pressure output port (32) to control the extrusion of the printing materials in the respective storage tanks;

step 5, generating a multi-material composite component, depositing a material system containing various materials on a two-dimensional forming substrate or a controllable variable-diameter rotary forming shaft according to the motion code of the 3D printing module (1) and the air source control signal of the air pump system (3) obtained in the step 2, and forming a three-dimensional entity through layer-by-layer accumulation;

s103, post-processing

According to the requirement of a printed product, further post-treatment such as curing, degreasing, sintering, surface sand blasting and the like can be carried out;

wherein the air pressure of the air pump system is controlled to be 2000-30000 pa, the viscosity of the material A is controlled to be 1500-10000 mPas, and the viscosity of at least one material system of the material B and the material C is controlled to be more than 1500 mPas.

Technical Field

The invention relates to the technical field of multi-material additive manufacturing, in particular to a direct-writing multi-material composite 3D printing system and method.

Background

The direct writing 3D printing technology is that printing ink (or slurry) with certain rheological property and shape-preserving capability is loaded into a needle cylinder, then the needle cylinder is installed on a movable three-dimensional platform, the needle cylinder runs according to a preset track under the control of a computer, and meanwhile, the printing ink is deposited on a forming platform through a feeding system. Different curing processes (such as solvent volatilization, UV illumination and the like) can be selected according to the curing mode of the printing ink to enable the ink to be cured and molded. And printing layer by layer to form the three-dimensional component. The preparation with low energy consumption, low cost and strong universality attracts a lot of attention, and the preparation method is widely applied to the printing of biological tissue engineering scaffolds and metal ceramics at present.

However, the existing direct-writing 3D printing still has a huge defect that only extrusion molding of a single uniform material can be realized in a single channel, and a huge challenge still exists in the aspect of multi-material composite extrusion molding, so that medical and engineering applications of the direct-writing 3D printing are greatly limited.

Disclosure of Invention

Aiming at the defect that direct-writing-based single-channel multi-material combined 3D printing equipment and method are lacked in the prior art, the invention provides a direct-writing-based multi-material combined 3D printing system and method. Firstly, a direct-writing multi-material composite 3D printing system is used, and secondly, a direct-writing multi-material composite 3D printing method is provided.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a multi-material composite 3D printing system and method based on direct writing includes:

and the 3D printing module generates a 3D printing component by controlling the multi-material composite printing nozzle to move in a three-dimensional space, so that the multi-material composite printing function is realized.

The material supply system is used for storing different printing materials and supplying multiple materials for the 3D printing module in real time;

the air pump system is used for supplying air pressure to the material supply system and the 3D printing module and controlling the extrusion amount and the extrusion speed of various materials in the 3D printing process;

the computer control system is used for controlling the operation of the whole multi-material direct-writing type 3D printing system, firstly, the air pump system is controlled to deliver stable air pressure to the material supply system and the 3D printing module, so that the material supply system can deliver materials to the 3D printing module according to a set proportion, and then the composite printing of multiple materials of the system is realized by controlling the motion track of the three-dimensional motion system and the multi-material extrusion speed of the printing nozzle.

Further, the 3D printing module further includes:

the 3D printing nozzle can move randomly in a three-dimensional space along with a three-dimensional motion system, the 3D printing nozzle can realize real-time variable-speed motion in the printing process, and the speed range is 0.1-5000 mm/s.

Wherein, the temperature of the material output by the 3D printing nozzle is controlled by the temperature control module.

The 3D printing nozzle structure is internally provided with a thin-wall inner core structure;

the thin-wall inner core structure is arranged and combined in any geometric structure such as a triangle, a circle, a square, a diamond and the like;

the thin-wall inner core structure can separate the material A from the material B, so that each material system can independently exist in the 3D printing spray head;

the printing fixing device is used for fixedly supporting all structures in the 3D printing module and ensuring the stability of the system;

and the 3D printing platform is used for supporting the printing component and ensuring the accuracy of the relative position of the printing component.

The 3D printing platform can be a two-dimensional forming substrate and can also be a controllable reducing rotary forming shaft.

The controllable variable-diameter rotary forming shaft is composed of an outer layer integral telescopic rubber film, a plurality of sectional telescopic variable-diameter cylinder structures, an independent hydraulic pushing device and a forming fixing device;

the controllable variable-diameter rotary forming shaft is formed by combining a plurality of sectional telescopic variable-diameter cylinder structures, and the axial diameter of each sectional telescopic variable-diameter cylinder structure can be changed in advance according to forming requirements, so that the forming of a variable-diameter symmetrical structure is realized;

the controllable variable-diameter rotary forming shaft can change the radial length of each segment of the sectional telescopic variable-diameter cylinder structure according to the forming requirement, so that the forming appearance of a forming sample piece is optimized and adjusted;

the controllable reducing rotary forming shaft can integrally rotate clockwise or anticlockwise at variable speed along the axial direction, and the rotating speed range is 6 r/min-600 r/min.

The radius of the telescopic reducing cylinder structure is determined by the pressure of the independent hydraulic pushing device;

wherein, the independent hydraulic pushing device can also be converted into mechanical pushing or pneumatic pushing;

the outer layer integral telescopic rubber membrane is made of a rubber material with a large telescopic ratio, and is integrally coated with the controllable reducing rotary forming shaft. When the diameter of the telescopic reducing cylinder structure changes, the shape of the outer layer integral telescopic rubber film can also change along with the shape;

and the three-dimensional control system controls the 3D printing nozzle to move randomly in a three-dimensional space.

And the heating module is used for controlling the heating temperature of each material in the 3D printing nozzle, so that the material can smoothly flow in the nozzle.

The material combination transmission pipeline is used for connecting the 3D printing spray head and the combined material receiving module;

the material combination transmission pipeline is formed by mechanical design, different materials are separated by a physical structure, and the material combination transmission pipeline can move randomly in space along with the 3D printing spray head.

The combined material receiving module is fixed on the combined material receiving module fixing device and is connected with the material supply system and the air pump system;

the combined material receiving module is directly connected with the material supply system, can receive different material systems from the material supply system, and then is conveyed to the 3D printing spray head through different channels of the material combined conveying pipeline;

the material systems in the combined material receiving module can independently control the conveying speed of the related material systems in the material combined conveying pipeline through the air pump system, and each material system is independent from each other in the combined material receiving module and separated through a mechanical structure.

Further, the material supply system includes:

a material A storage tank, a material B storage tank and a material C storage tank;

the material supply system is directly connected with the air pump system and the computer control system, and all material systems of the material supply system can be independently controlled to be conveyed through the air pump system and the computer control system;

the material A storage tank conveys the material A system to a material A inlet hole of the combined material receiving module through a material A conveying device; ,

wherein the material B storage tank conveys the material B system to a material B inlet hole of the combined material receiving module through a material B conveying device;

wherein the material C storage tank conveys the material C system to a material C inlet hole of the combined material receiving module through a material C conveying device;

the material supply system is composed of two or more material storage tanks, and the material system of each material storage tank can be different from each other.

Further, the air pump system further includes:

the signal control system is used for receiving a control instruction of the computer control system and then controlling the pressure of each material through the air pressure output port;

wherein, the air pressure output port is independently connected with each material conveying pipeline and is respectively controlled.

Further, the computer control system further comprises:

the computer control system controls the output speed and the output sequence of each material of the material storage system by controlling the air pump system, and the materials are conveyed to the combined material receiving module through the conveying pipeline;

the computer control system controls a three-dimensional motion system in the 3D printing module to perform spatial three-dimensional motion according to a certain track through software;

the computer control system can control the temperature control module to control the temperature of the material.

Further, the computer control system further comprises:

the computer control system controls the output speed and the output sequence of each material of the material storage system by controlling the air pump system, and the materials are conveyed to the combined material receiving module through the conveying pipeline;

the computer control system controls a three-dimensional motion system in the 3D printing module to perform spatial three-dimensional motion according to a certain track through software;

the computer control system can control the temperature control module to control the temperature of the material.

Additionally, the direct-writing multi-material composite 3D printing method comprises the following steps:

s101, selecting printing materials

A, B, C can be selected as printing materials, and three different material systems are used for direct-writing multi-material composite printing;

the A, B, C material system can be a single homogeneous material, or a blended material or a composite material formed by mixing a plurality of materials;

the single homogeneous material, the blending material and the matrix material in the composite material can be high molecular polymers such as acrylonitrile-butadiene-styrene plastics, polycarbonates, nylons, polycarbonate, acrylonitrile-butadiene-styrene copolymer and mixture, thermoplastic plastic materials, polysulfone materials and the like, photosensitive resins such as Somos Next materials, resin Somos 11122 materials, Somos 19120 materials, epoxy resins and the like, rubber materials and the like; the reinforcing material of the composite material can be metal particles, ceramic particles, carbon fibers, glass fibers, nylon fibers and the like;

the material A is the outermost layer material of the multiple materials of the sprayer, the main function is to enable the material B and the material C to be completely coated on the inner side of the material A, and the materials can be melts/melts, colloids or suspensions and the like with certain rheological characteristics and shape-preserving capability, or can be rapidly solidified and shaped under certain solidification conditions such as temperature, ultraviolet light, humidity and the like;

the material B and the material C are inner layer materials of the printing nozzle and can be functional materials with the characteristics of electric conduction, heat conduction, enhancement and the like;

wherein, one of the material B and the material C can be a permanent liquid material, and the other material is coated on the outer side of the permanent liquid material;

wherein, the inner side of the material A can be compounded by more than one different materials, the final shape of each material is determined by the mechanical physical structure of the spray head, and the materials of all channels in the spray head are different;

s102, manufacturing a multi-material composite component, which specifically comprises the following steps:

step 1, constructing a three-dimensional model, establishing the three-dimensional model according to requirements, and then performing discretization on the model;

step 2, selecting materials, namely selecting the optimal printing materials and the optimal structural shape of the printing nozzle according to the performance requirements of the components and the printing process conditions;

step 3, movement programming of multi-material composite printing, and determining a movement code of the 3D printing module and a control signal of the air pump system by combining the actual situation of the multi-material composite component;

step 4, putting the materials into a material supply system, respectively putting the material A, the material B and the material C into a material A storage tank, a material B storage tank and a material C storage tank, and connecting a compressed air source into a material A output device, a material B output device and a material C output device through an air pressure output port so as to control the extrusion of the printing materials in the respective storage tanks;

step 5, generating a multi-material composite component, depositing a material system containing various materials on a two-dimensional forming substrate or a controllable variable-diameter rotary forming shaft according to the motion code of the 3D printing module and the air source control signal of the air pump system obtained in the step 2, and forming a three-dimensional entity through layer-by-layer accumulation;

s103, post-processing

According to the requirement of a printed product, further post-treatment such as curing, degreasing, sintering, surface sand blasting and the like can be carried out;

wherein the air pressure of the air pump system is controlled to be 2000-30000 pa, the viscosity of the material A is controlled to be 1500-10000 mPas, and the viscosity of at least one material system of the material B and the material C is controlled to be more than 1500 mPas.

The invention has the following beneficial effects:

in a first aspect: the invention can realize the multi-material combined molding in the printing channel, and can realize the multi-material combined printing of any geometric section according to the design of the extrusion head;

in a second aspect: the original controllable reducing rotary forming shaft can dynamically regulate and control the diameter of each section of forming shaft according to the pre-design, thereby realizing the high-efficiency three-dimensional forming of an unsupported symmetrical structure;

in a third aspect: the thickness, the precision and the roughness of the core-shell symmetrical structure can be dynamically regulated in real time by cooperatively regulating the reciprocating speed of the extrusion head and the controllable variable-diameter rotary forming shaft;

in a fourth aspect: the device and the method provided by the invention are convenient to operate and strong in universality, and for example, the metal or ceramic slurry is respectively selected as the outer layer material and the inner layer material, and combined printing of the metal and ceramic materials can be realized after printing and post-treatment; if the outer layer material and the inner layer material are respectively selected from polymer and conductive liquid metal, the printing of the conductive channel can be realized after printing and post-treatment; if the outer layer material and the inner layer material are respectively selected from cell-carrying biological materials and sacrificial materials, the printing and the post-processing can realize the printing and the forming of the tissue blood vessel. Therefore, the method has great application potential in the engineering and medical fields.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 1 is a schematic diagram of the system configuration of the present invention.

Fig. 2 is a schematic diagram of a mechanical multi-material composite 3D printing nozzle according to the present invention.

FIG. 3 is a cross-sectional view of a multi-material 3D printing nozzle with different structures according to the present invention.

Fig. 4 is a schematic feeding diagram of the 3D printing nozzle according to the present invention.

FIG. 5 is a schematic view of a rotational molding process according to the present invention.

FIG. 6 is a schematic view of the variable diameter rotary forming shaft according to the present invention.

The reference numerals in the figures denote:

the system comprises a 3D printing module 1, a material supply system 2, an air pump system 3 and a computer control system 4;

the device comprises a 3D printing spray head 11, a printing fixing device 12, a printing component 13, a 3D printing platform 14, a three-dimensional motion system 15, a heating module 16, a material combination transmission pipeline 17, a combined material receiving module fixing device 18, a combined material receiving module 19, an outer layer integral telescopic rubber film 141, a sectional telescopic reducing cylinder structure 142, an independent hydraulic pushing device 143 and a forming fixing device 144;

a material a storage tank 21, a material a output device 24, a material B storage tank 22, a material B output device 25, a material C storage tank 23, a material C output device 26;

an air pump control interface 31 and an air pump output interface 32.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to solve the problem that multi-material composite printing is difficult to realize in the prior art, and the specific technical scheme is shown in figure 1, and the multi-material composite 3D printing system and method based on the direct-writing mode comprise the following steps:

the 3D printing system comprises a 3D printing module 1, a material supply system 2, an air pump system 3 and a computer control system 4, wherein the 3D printing module 1 is connected with the material supply system 2, the air pump system 3 and the computer control system 4, a 3D printing component is generated by controlling a multi-material composite printing spray head to move in a three-dimensional space, so that the multi-material composite printing function is realized, the material supply system 2 is connected with the air pump system 3 and the 3D printing module 1 and is used for storing different printing materials and supplying the multi-material of the 3D printing module 1 in real time, the air pump system 3 is used for supplying air pressure of the material supply system 2 and the 3D printing module 1 and controlling the extrusion amount and the extrusion speed of various materials in the 3D printing process, and the computer control system 4 is used for controlling the operation of the whole multi-material direct writing type 3D printing system, the method comprises the steps of firstly controlling an air pump system 3 to deliver stable air pressure to a material supply system 2 and a 3D printing module 1, enabling the material supply system 2 to deliver materials to the 3D printing module 1 according to a set proportion, and then controlling the motion track of a three-dimensional motion system 15 and the multi-material extrusion speed of a 3D printing nozzle 11 to achieve composite printing of multiple materials of the system.

Further, the 3D printing module further includes:

the 3D printing nozzle 11 can move freely in a three-dimensional space along with the three-dimensional motion system 15, the 3D printing nozzle 11 can move at a variable speed in real time in the printing process, and the speed range is 0.1-5000 mm/s.

Wherein, the temperature of the material output by the 3D printing nozzle 11 is controlled by the temperature control module 16;

a thin-wall inner core structure 112 is arranged in the 3D printing nozzle 11;

the thin-wall inner core structure 112 is arranged and combined in any geometric structure such as a triangle, a circle, a square, a diamond and the like;

the thin-wall inner core structure 112 can separate the material A111 from the material B113, so that each material system can independently exist in the 3D printing nozzle 11;

the printing fixing device 12 is used for fixedly supporting all structures in the 3D printing module 1 and ensuring the stability of the system;

a 3D printing platform 14 for supporting the printing member 13 and ensuring the accuracy of its relative position;

the 3D printing platform 14 may be a two-dimensional forming substrate, or may be a controllable variable-diameter rotary forming shaft;

the controllable variable-diameter rotary forming shaft consists of an outer layer integral telescopic rubber film 141, a plurality of segmented telescopic variable-diameter cylinder structures 142, an independent hydraulic pushing device 143 and a forming fixing device 144;

the controllable variable-diameter rotary forming shaft is formed by combining a plurality of sectional telescopic variable-diameter cylinder structures 142, and the axial diameter of each sectional telescopic variable-diameter cylinder structure 142 can be changed in advance according to forming requirements, so that the forming of a variable-diameter symmetrical structure is realized;

the controllable variable-diameter rotary forming shaft can change the radial length of each segment of the segmented telescopic variable-diameter cylinder structure 142 according to the forming requirement, so that the forming appearance of a forming sample piece is optimized and adjusted;

the controllable reducing rotary forming shaft can integrally rotate clockwise or anticlockwise at variable speed along the axial direction, and the rotating speed range is 6 r/min-600 r/min;

wherein, the radius of the telescopic reducing cylinder structure is determined by the pressure of the independent hydraulic pushing device 143;

wherein, the independent hydraulic pushing device 143 can also be changed into mechanical pushing or pneumatic pushing;

the outer layer integral telescopic rubber film 141 is made of a rubber material with a large telescopic ratio, and integrally covers the controllable reducing rotary forming shaft, and when the diameter of the telescopic reducing cylinder structure changes, the shape of the outer layer integral telescopic rubber film can also change along with the shape;

the three-dimensional motion system 15 controls the 3D printing nozzle 11 to move randomly in a three-dimensional space;

the heating module 16 is used for controlling the heating temperature of each material in the 3D printing nozzle 11 so that the material can smoothly flow in the nozzle;

the material combination conveying pipeline 17 is used for connecting the 3D printing spray head 11 and the combined material receiving module 19;

the material combination transmission pipeline 17 is formed by mechanical design, different materials are separated by a physical structure, and the material combination transmission pipeline 17 can move randomly in space along with the 3D printing spray head 11;

a combined material receiving module 19 fixed on the combined material receiving module fixing device 18 and connected with the material supply system 2 and the air pump system 3;

the combined material receiving module 19 is directly connected with the material supply system 2, can receive different material systems from the material supply system 2, and then is conveyed to the 3D printing spray head 11 through different channels of the material combined conveying pipeline 17;

wherein, each material system in the combined material receiving module 19 can independently control the conveying speed of the related material system in the material combination conveying pipeline 17 through the air pump system 3, and each material system is independent from each other in the combined material receiving module 19 and separated by a mechanical structure.

Further, the material supply system includes:

a material a storage tank 21, a material B storage tank 22, and a material C storage tank 23;

wherein, the material supply system 2 is directly connected with the air pump system 3 and the computer control system 4, and each material system of the material supply system 2 can be independently controlled and conveyed by the air pump system 3 and the computer control system 4;

wherein the material a storage tank 21 delivers the material a system to the material a intake of the combined material receiving module 19 through the material a delivering means 24; ,

wherein the material B storage tank 22 delivers the material B system to the material B inlet of the combined material receiving module 19 through the material B delivery means 25;

wherein the material C storage tank 23 delivers the material C system to the material C intake of the combined material receiving module 19 through the material C delivery means 26;

the material supply system 2 is composed of two or more material storage tanks, and the material system of each material storage tank may be different from each other.

Further, the air pump system further includes:

the signal control system 31 is used for receiving a control command of the computer control system and then controlling the pressure of each material through the air pressure output port 32;

wherein, the air pressure output port 32 is connected with each material conveying pipeline independently and controlled respectively.

Further, the computer control system further comprises:

the computer control system 4 controls the output speed and the output sequence of each material of the material storage system by controlling the air pump system 3, and the materials are conveyed to the combined material receiving module 19 through a conveying pipeline;

the computer control system 4 controls the three-dimensional motion system 15 in the 3D printing module 1 to perform spatial three-dimensional motion according to a certain track through software;

the computer control system 4 can control the temperature control module 16 to control the temperature of the material.

A multi-material composite 3D printing method based on direct writing is characterized by comprising the following steps:

s101, selecting printing materials

A, B, C can be selected as printing materials, and three different material systems are used for direct-writing multi-material composite printing;

the A, B, C material system can be a single homogeneous material, or a blended material or a composite material formed by mixing a plurality of materials;

the single homogeneous material, the blending material and the matrix material in the composite material can be high molecular polymers such as acrylonitrile-butadiene-styrene plastics, polycarbonates, nylons, polycarbonate, acrylonitrile-butadiene-styrene copolymer and mixture, thermoplastic plastic materials, polysulfone materials and the like, photosensitive resins such as Somos Next materials, resin Somos 11122 materials, Somos 19120 materials, epoxy resins and the like, rubber materials and the like; the reinforcing material of the composite material can be metal particles, ceramic particles, carbon fibers, glass fibers, nylon fibers and the like;

the material A111 is the outermost layer material of the multiple materials of the sprayer, and mainly has the main function that the material B and the material C are completely coated on the inner side of the material A, and can be a melt/solution, a colloid or a suspension with certain rheological property and shape-preserving capability, or can be rapidly solidified and shape-preserved under certain solidification conditions such as temperature, ultraviolet light, humidity and the like;

the material B113 and the material C114 are inner layer materials of the printing nozzle, and can be functional materials with the characteristics of electric conduction, heat conduction, enhancement and the like;

wherein, one of the B material 113 and the C material 114 can be a permanent liquid material, and the other material is coated outside the permanent liquid material;

wherein, the inner side of the material A can be compounded by more than one different materials, the final shape of each material is determined by the mechanical physical structure of the spray head, and the materials of all channels in the spray head are different;

s102, manufacturing a multi-material composite component, which specifically comprises the following steps:

step 1, constructing a three-dimensional model, establishing the three-dimensional model according to requirements, and then performing discretization on the model;

step 2, selecting materials, namely selecting the optimal printing materials and the optimal structural shape of the printing nozzle according to the performance requirements of the components and the printing process conditions;

step 3, movement programming of multi-material composite printing, and determining a movement code of the 3D printing module 1 and a control signal of the air pump system 3 by combining the actual situation of the multi-material composite component;

step 4, putting the materials into the material supply system 2, putting the materials A111, B113 and C114 into the material A storage tank 21, the material B storage tank 22 and the material C storage tank 23 respectively, and connecting a compressed air source into the material A output device 24, the material B output device 25 and the material C output device 26 through the air pressure output port 32 to control the extrusion of the printing materials in the respective storage tanks;

step 5, generating a multi-material composite component, depositing a material system containing various materials on a two-dimensional forming substrate or a controllable variable-diameter rotary forming shaft according to the motion code of the 3D printing module 1 and the air source control signal of the air pump system 3 obtained in the step 2, and forming a three-dimensional entity through layer-by-layer accumulation;

s103, post-processing

According to the requirement of a printed product, further post-treatment such as curing, degreasing, sintering, surface sand blasting and the like can be carried out;

wherein the air pressure of the air pump system is controlled to be 2000-30000 pa, the viscosity of the material A is controlled to be 1500-10000 mPas, and the viscosity of at least one material system of the material B and the material C is controlled to be more than 1500 mPas.

A first, more preferred embodiment of the method of the present application is as follows:

3D printing material: selecting a solution with a viscosity of 5000 mPas for the material A, a viscosity of 2000 mPas for the material B, a viscosity of 1500 mPas for the material C, and certain rheological property and shape-preserving capability;

building a three-dimensional model: establishing a three-dimensional model according to engineering requirements, and then performing discretization processing on the model before printing through 3D printing software to obtain material information of each position point of the three-dimensional sample, motion information of each part of the mixing device, air pressure information of a multifunctional air pressure system and the like;

a printing program movement programming is carried out, and a movement code of a three-dimensional movement assembly in a 3D printing module 1 in the 3D printing system and an air source control signal of an air pump system 3 are determined according to the characteristics of the components;

putting the materials into the material supply system 2, and connecting a compressed air source into the material output device A24, the material output device B25 and the material output device C26 through the air pressure output port 32 to control the extrusion of the printing materials in the respective storage tanks;

and (2) generating a multi-material composite component, selecting a two-dimensional forming substrate (shown in figure 1), installing a coaxial printing nozzle (shown in the left figure of figure 2), wherein the section of the printing nozzle is shown in the left figure of figure 3, according to the motion code of the 3D printing system and the air source control signal of the multifunctional air pressure system obtained in the step (2), A, B, C three materials enter the 3D printing nozzle through a combined material receiving and mixing module (shown in the left figure of figure 4), and accumulating the extruded material layer containing multiple materials on a forming platform layer by layer.

And (3) post-treatment: and taking out the multi-material combined printing part, placing the part in a drying box, and further volatilizing liquid in the material to promote the part to be solidified.

A more preferred second embodiment of the method of the present application is as follows:

3D printing material: selecting a solution with a viscosity of 8000mPa & s for the material A, a viscosity of 4000mPa & s for the material B, a viscosity of 3000mPa & s for the material C, and certain rheological property and shape-preserving capability;

building a three-dimensional model: establishing a three-dimensional model according to engineering requirements, and then performing discretization processing on the model before printing through 3D printing software to obtain material information of each position point of the three-dimensional sample, motion information of each part of the mixing device, air pressure information of a multifunctional air pressure system and the like;

a printing program movement programming is carried out, and a movement code of a three-dimensional movement assembly in a 3D printing module 1 in a 3D printing system, an air source control signal of an air pump system 3 and a movement code of a hydraulic controllable variable-diameter rotation forming shaft 14 are determined according to the characteristics of components;

putting the materials into the material supply system 2, and connecting a compressed air source into the material output device A24, the material output device B25 and the material output device C26 through the air pressure output port 32 to control the extrusion of the printing materials in the respective storage tanks;

the method comprises the steps of generating a multi-material composite component, selecting a hydraulic controllable reducing rotary forming shaft 14 which can freely rotate along an axis (the rotating speed is 120r/min), enabling a 3D printing nozzle 11 to reciprocate along the axis (shown in figure 5), enabling the moving speed to be 1mm/s, enabling the diameter of the controllable reducing rotary forming shaft to be sequentially reduced from left to right (shown in figure 6), installing the 3D printing nozzle (shown in figure 2 right), enabling the section of the 3D printing nozzle to be shown in figure 3 right, obtaining a motion code of a 3D printing system and an air source control signal of a multifunctional air pressure system 3 according to the step 2, enabling A, B, C three materials to enter the 3D printing nozzle through a combined material receiving and mixing module (shown in figure 4 right), and accumulating extruded materials containing multiple materials on a forming platform layer by layer.

And (3) post-treatment: and taking out the multi-material combined printing part, placing the part in a drying box, and further volatilizing liquid in the material to promote the part to be solidified.

It should be noted that: in accordance with the patented embodiments, as set forth above, these embodiments are not intended to be exhaustive or to limit the patented embodiments to the precise forms disclosed. Obviously, many modifications and variations are possible in light of the above teaching. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.