A multi-material large scale volumetric 3D printing system and method

Abstract

The present application relates to a kind of multi-material large-size volume 3D printing system and printing method, including substrate;Forming cavity;Rotary table;Projection module, and quantity is two, two projection systems are projected on same forming cavity;Monitoring module, its quantity is two, real-time printing information is transmitted to control module and is analyzed, carries out real-time light dose correction;Motion module, it is used to control the synchronous movement of the projection module and monitoring module of same group, the present application utilizes DMD splicing technology to enlarge the projection area of projection system, further enlarge the projection area in conjunction with the projection orientation cooperation between double projection systems, improve the printable size of volume 3D printing technology, and can flexibly replace projection module light source, suitable for the synchronous solidification of photosensitive resin based on multiple solidification principles, greatly improve the manufacturing efficiency and printing size of multi-material volume 3D printing.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a multi-material, large-size 3D printing system and printing method. Background Technology

[0002] Volumetric 3D printing is a novel photopolymer additive manufacturing technology that simultaneously prints all points within a target area, thus enabling ultra-high-speed manufacturing. Unlike traditional layer-by-layer printing methods, it accumulates energy in three-dimensional space within the target area. Once the solidification threshold is reached, the target entity is formed as a single unit, avoiding the stair-step effect of traditional 3D printing and improving the surface quality of the printed sample. Furthermore, the printing process requires no auxiliary supports, avoiding the surface quality issues caused by post-processing support removal and the difficulty in removing internal supports from hollow structures.

[0003] However, current volumetric 3D printing uses a rotating transparent molding cavity, which generates centrifugal force. To reduce the relative sliding between the photosensitive resin and the molding cavity, a high-viscosity photosensitive resin must be used. On the other hand, when using low-viscosity photocurable resin, the rotation speed of the resin bath is limited, easily leading to uneven energy accumulation in the target area and resulting in inconsistent mechanical properties in the cured region. Currently, the size of volumetric 3D printed samples is limited by the projection area of ​​the projection system, which restricts the further application of volumetric 3D printing. Therefore, increasing the printing size of volumetric 3D printing and expanding its adaptability in low-viscosity material systems are current challenges.

[0004] Multimaterial components are widely used in aerospace, biomedicine, and smart electronics due to their ability to incorporate the physical and chemical properties of multiple materials. However, current multimaterial photopolymer 3D printing suffers from low printing accuracy, insufficient automation and integration of printing equipment, high cost, and complex processes, making it difficult to meet current industrial manufacturing needs. Furthermore, most photopolymer multimaterial structures are manufactured by stacking layers, making it impossible to combine materials with different properties within the same layer. This layered manufacturing method also results in a time-consuming and inefficient printing process.

[0005] To address this, we propose a multi-material, large-size 3D printing system and printing method. Summary of the Invention

[0006] In response to the shortcomings of the existing production technologies, the applicant provides a multi-material large-size volume 3D printing system and printing method, thereby solving the problems of small processing size, low printing flexibility, and high viscosity limitation of printing materials in current volume 3D printing.

[0007] The technical solution adopted in this invention is as follows:

[0008] A multi-material, large-volume 3D printing system, comprising:

[0009] The substrate has an annular groove on its upper surface.

[0010] The molding cavity, located at the center of the annular groove on the substrate, is used to support the printing substrate and the printing target structure;

[0011] There are four turntables that are slidably engaged in an annular groove. The four turntables are divided into two groups, and the two turntables in each group are symmetrically distributed with the center of the annular groove as the point.

[0012] The projection module consists of two modules, each projecting two different photosensitive wavelengths. These modules are distributed on two turntables in the same group. Each projection module includes a projection system that moves vertically and horizontally relative to the turntable. Both projection systems project onto the same molding cavity.

[0013] There are two monitoring modules, which are distributed on two turntables in another group. The monitoring modules move vertically relative to the turntables and are used to monitor the printing process. They transmit real-time printing information to the control module for analysis and real-time light dose correction.

[0014] The motion module is used to control the synchronous movement of the projection module and the monitoring module in the same group.

[0015] Furthermore, a Z-axis displacement stage capable of being raised and lowered is provided at the center of the annular groove of the substrate, and the molding cavity is connected to the Z-axis displacement stage.

[0016] Furthermore, the monitoring module includes a CCD camera, an auxiliary observation light source, an optical path system, and a data transmission component. The auxiliary observation light source operates in the red light band and does not affect the printing process. The monitoring module is installed on the lead screw slide to monitor the printing process, transmits real-time printing information to the control module for analysis, performs real-time illumination dose correction, and improves printing accuracy.

[0017] Furthermore, the sidewall transparency of the molding cavity is greater than 90%.

[0018] Furthermore, it also includes auxiliary modules, including oxygen content regulators, humidity regulators, and temperature regulators, which are used to adjust the environmental information such as oxygen content, temperature, humidity, and light intensity of the molding cavity to a standard state.

[0019] Furthermore, it also includes a control module, which coordinates and controls the projection module, motion module, monitoring module, molding cavity, and auxiliary module to ensure the automated and safe operation of each stage.

[0020] Furthermore, the motion module controls two projection modules in the same group to move symmetrically on the horizontal plane and simultaneously move up and down on the vertical plane.

[0021] Furthermore, the motion module controls the two projection modules in the same group to move in a point-symmetrical manner on both the horizontal and vertical planes. The micromirror unit of the projection system has multiple flip angles in multiple directions, with a flip angle of ±12°, so as to deliver the sequential angle projection energy to the same molding cavity 600.

[0022] Furthermore, the projection system is composed of multiple DMD chips spliced ​​together, and the micromirror spacing of a single DMD chip is 13.68μm or 5.4μm.

[0023] Furthermore, the projection power of the projection system is 0-50mW / cm². 2 .

[0024] Furthermore, the two projection modules operate in low-band and high-band projection bands, respectively, and can be connected in series or in parallel.

[0025] A printing method for a multi-material, large-size 3D printing system includes the following steps:

[0026] S1. Establish a 3D digital model of the target sample, set it as an STL format file, slice it according to a layer thickness of 50 micrometers, and then convert it into a series of angular projections using tomographic projection and reverse tomographic projection algorithms. After image filtering, set the negative numbers of the numerical matrix in the angular projection to 0 or simultaneously subtract the minimum value in the matrix, and input it to DMD chips in different locations. When a single DMD chip is insufficient to meet the actual projection size, the control module can adaptively coordinate the splicing of the projection sequence by adjacent DMD chips, thereby improving the printable size.

[0027] S2. Two photosensitive resins with different photosensitive wavelengths are uniformly mixed with an additive phase. The additive phase can be functional materials such as conductive particles, magnetic particles, and temperature and humidity sensitive particles. Before printing, the mixed photosensitive material should be placed in the air away from light for a period of time or a free radical scavenger should be added before adding it to the molding cavity. The two photosensitive resins with different photosensitive wavelengths operate in the 300nm-600nm range, corresponding to two projection modules respectively.

[0028] S3. Activate the auxiliary module and adjust the gas environment, temperature, and lighting conditions in the molding cavity to the standard state. The temperature in the molding cavity is 25℃, and no other light enters to affect the photopolymerization reaction of the projection module.

[0029] S4. Activate the motion module. The rotating platform drives the projection module and monitoring module to rotate at a constant speed around the center of the forming cavity. The relative position of the two remains unchanged during the movement. The rotation speed is 25-100° / s. The XY displacement stage can drive the projection system to move in the XY direction, and the Z-axis displacement stage can drive the forming cavity to move in the Z-axis direction. After printing one stage, the forming cavity can move along the Z-axis direction to print the next stage, expanding the printing size in the Z-axis direction.

[0030] S5. Activate the projection module. The projection system projects the serialized angle onto the molding cavity, forming a three-dimensional spatial energy accumulation in the target area. Once the energy exceeds the solidification threshold, the target entity is integrally formed.

[0031] S6. Activate the monitoring module to monitor the printing completion rate during the printing process. The control module will reconstruct a 3D model from the real-time images of the printing process and compare it with the target model. The difference will be compensated in the subsequent projection. When the completion rate reaches 100%, the printing will proceed to the next stage.

[0032] S7. The control module determines whether printing along the Z-axis needs to continue. If printing continues, the S4-S7 stages are repeated. If printing is completed, the next stage is performed.

[0033] S8. Turn off the projection module, motion module, monitoring module, and other modules;

[0034] S9. Remove the printed material from the molding cavity, clean it with isopropyl alcohol in an ultrasonic cleaner, and then perform post-curing treatment in a post-curing chamber.

[0035] The rotation period of the projection module should be consistent with the period of the projection sequence to ensure the accuracy of spatial dose establishment in a single period.

[0036] Furthermore, the projected light needs to be processed by a collimating lens to be emitted horizontally, reducing energy loss and beam diffusion.

[0037] Furthermore, the two photosensitive resins with different photosensitive wavelengths are a cationic photosensitive resin and a free radical photosensitive resin, respectively.

[0038] Furthermore, the two polymer networks are formed through two independent mechanisms to create a composite structure with highly tunable mechanical properties.

[0039] Furthermore, the printed photosensitive resins have high transmittance in the visible light band, and the curing of one resin does not affect the specific dose accumulation of another resin cured by a different mechanism, ensuring the dimensional accuracy of multi-material printing.

[0040] The beneficial effects of this invention are as follows:

[0041] This invention has a simple structure and is easy to operate. With the combined action of two projection modules and the rotation of the molding cavity, it can achieve large-size printing. It can also print with two photosensitive resins with different photosensitive wavelengths. The two polymer networks are formed through two independent mechanisms, forming a composite structure with highly adjustable mechanical properties, which has strong practicality.

[0042] 1. The present invention is equipped with a dual-light source projection system, which operates in different wavelength bands to cure photocurable resins with different physicochemical properties and manufacture composite performance parts.

[0043] 2. This invention utilizes DMD splicing technology to expand the projection area of ​​the projection system, and further expands the projection area by combining the projection orientation coordination between the two projection systems, thereby increasing the printable size of multi-material volume 3D printing technology.

[0044] 3. In this invention, the printing cavity can move in the Z-axis direction, which can further enable the Z-axis extension printing of the printed structure and further improve the printing size of multi-material volume 3D printing.

[0045] 4. The material system for 3D printing is further expanded by utilizing the rotation of the projection system. The static forming of the forming cavity also increases the rotation speed of the projection system and improves the printing accuracy. Attached Figure Description

[0046] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0047] Figure 2 This is a schematic diagram of the DMD splicing of the present invention.

[0048] Figure 3 This is a schematic diagram showing the relative positions of the projection system of the present invention;

[0049] Figure 4 This is a flowchart of the multi-material large-size volume 3D printing process of the present invention.

[0050] in:

[0051] Screw slide 1 (100a), Screw slide 1; 100b, Projection system 1; 100c, XY axis displacement stage 1; 100d, Turntable 1; Screw slide 2 (200a), Screw slide 2 (200a); 200b, Projection system 2; 200c, XY axis displacement stage 2; 200d, Turntable 2; Screw slide 3 (300a), Screw slide 3; 300b, Turntable 3; 300c, Auxiliary observation light source; Screw slide 4 (400a), Screw slide 4; 400b, Turntable 4; 400c, CCD camera; 500, Z-axis displacement stage; 600, Forming cavity; 700, Platform; 800, Auxiliary module; 900, Control module. Detailed Implementation

[0052] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0053] Example 1

[0054] Figure 1 This is a schematic diagram of the 3D printing system structure of an embodiment of the multi-material large-size volume 3D printing system and printing method of the present invention. It includes a substrate, a forming cavity 600, a turntable, a projection module, a monitoring module, and a motion module. Under the combined action of the two projection modules and the rotation of the forming cavity 600, large-size printing can be achieved. At the same time, it can print two photosensitive resins with different photosensitive wavelengths. The two polymer networks are formed through two independent mechanisms to form a composite structure with highly adjustable mechanical properties, which has strong practicality.

[0055] In this embodiment, the substrate serves as the carrier of the entire device, and its upper surface is horizontally arranged and has an annular groove.

[0056] The forming cavity 600 is used to support the printing substrate and the printing target structure. The forming cavity 600 is located at the center of the annular groove on the substrate. At the same time, a Z-axis displacement stage 500 that can be raised and lowered is set at the center of the annular groove on the substrate. The forming cavity 600 is connected to the Z-axis displacement stage 500. In order to ensure the accuracy of three-dimensional energy transfer, it should have a transparency of more than 90% in the projection working band.

[0057] In this embodiment, there are four turntables that are slidably engaged in the annular groove. The four turntables are divided into two groups, and the two turntables in each group are symmetrically distributed with respect to the center of the annular groove. The symmetrical distribution also includes the linear symmetrical distribution, that is, they can be distributed face to face or tilted relative to each other on the horizontal plane, thereby increasing the projection range.

[0058] In this embodiment, there are two projection modules, which project two different photosensitive wavelengths and are distributed on two turntables in the same group. They can be connected in series or in parallel. The projection module includes a projection system, which moves vertically and horizontally relative to the turntable. The two projection systems project onto the same molding cavity 600.

[0059] In this embodiment, the projection module is mounted on a lead screw slide (lead screw slide 100a, lead screw slide 200a) and consists of two identical projection systems (projection system 100b, projection system 200b), as follows: Figure 2As shown, each projection system (Projection System 100b and Projection System 200b) is composed of multiple DMD chips. Depending on the printing precision, the micromirror spacing of a single DMD chip can be selected as 13.68μm or 5.4μm. A smaller micromirror spacing is more beneficial for improving the resolution of the printed structure. The micromirror units of the projection systems (Projection System 100b and Projection System 200b) have multiple rotation angles, with a rotation angle of ±12°, allowing both projection systems (Projection System 100b and Projection System 200b) to project onto the same forming cavity 600. Figure 3 As shown, by changing the relative position of the dual projection system, a large-area projection area can be achieved, and the sequential angle projection energy can be delivered to the forming cavity 600.

[0060] In this embodiment, there are two monitoring modules, distributed on two turntables in another group. The monitoring modules move vertically relative to the turntables. The monitoring modules include a CCD camera 400c, an auxiliary observation light source 300c, an optical path system, and a data transmission component. The auxiliary observation light source 300c operates in the red light band and does not affect the printing process. The monitoring modules are installed on the lead screw slide to monitor the printing process, transmit real-time printing information to the control module for analysis, perform real-time illumination dose correction, and improve printing accuracy.

[0061] The motion module in this embodiment is used to control the synchronous movement of the projection module and the monitoring module in the same group.

[0062] Specifically, such as Figure 1 As shown, the motion module is used to control the movement of the lead screw slides (lead screw slide 100a, lead screw slide 200a, lead screw slide 300a, lead screw slide 400a), the XY axis displacement stages (XY axis displacement stages 100c, XY axis displacement stages 200c), the bottom turntables (turntable 100d, turntable 200d, turntable 300b, turntable 400b), and the Z axis displacement stage 500. The lead screw slides drive the projection module and the monitoring module (XY axis displacement stage 300c, CCD camera 400c) to rotate around... The center rotates, and the lead screw slides (lead screw slide 100a and lead screw slide 200a) connected to the projection module are connected to the turntable (turntable 100d and turntable 200d) through the XY axis displacement stages (XY axis displacement stages 100c and XY axis displacement stages 200c). The monitoring module can be connected to the bottom turntable (turntable 300b and turntable 400b) through the lead screw slides (lead screw slide 300a and lead screw slide 400a). The forming cavity 600 is connected to the bottom platform 700 through the Z axis displacement stage 500.

[0063] In this embodiment, specifically, the motion module controls two projection modules in the same group to move symmetrically on the horizontal plane. The symmetrically serialized image obtained by the forward and reverse tomographic projection algorithm can be sent to the two projection modules respectively, which can further improve the light dose accumulation size of the target space and expand the single projection printing size. At the same time, the projection modules can move up and down on the vertical plane simultaneously, which can achieve selective curing of the molding cavity at any position in the 600Z direction.

[0064] In another embodiment, the motion module controls two projection modules in the same group to move symmetrically in both the horizontal and vertical planes. The micromirror unit of the projection system has multiple flip angles, with a flip angle of ±12°. When flipped by +12°, the reflected light is imaged onto the target area along the optical axis, forming a bright pixel. When the mirror deviates from the equilibrium position by -12°, the reflected beam cannot be projected onto the target area, thus presenting a dark pixel. The periodicity of each state can be adjusted to change its projection grayscale value, enabling the sequential angle projection energy to be delivered to the same molding cavity 600, achieving energy uniformity and printing synchronization in the target area. The projected light needs to be processed by a collimating lens to be emitted horizontally, reducing energy loss and beam diffusion.

[0065] In this embodiment, the monitoring module includes a CCD camera 400c, an auxiliary observation light source 300c, an optical path system, and a data transmission component. The auxiliary observation light source 300c operates in the red light band and does not affect the printing process. The monitoring module is installed on the lead screw slide and is used to monitor the printing process, transmit real-time printing information to the control module for analysis, perform real-time illumination dose correction, and improve printing accuracy.

[0066] In another embodiment, to improve the printing effect, an auxiliary module 800 is also included. The auxiliary module 800 includes an oxygen content regulator, a humidity regulator, and a temperature regulator, which are used to adjust the ambient temperature of the molding cavity 600 to reach a standard state, that is, the oxygen content is in a low oxygen or oxygen-free environment, the temperature is maintained at about 25°C to avoid the cross-linking and curing of the photosensitive resin due to excessively high or low temperatures, the humidity is between 40% and 70% to prevent static electricity from affecting the printing effect, and the light intensity is in a backlit environment to avoid other uncontrollable light from affecting the printing of the target entity, thereby improving the controllability of the printing process.

[0067] In another embodiment, a control module 900 is also included. The control module 900 coordinates and controls the projection module, motion module, monitoring module, molding cavity 600 and auxiliary module 800 to ensure the automated and safe operation of each link and improve the intelligent effect.

[0068] In another embodiment, the control module includes a host computer, motion control components, and control components for projection modules of different wavelengths. The host computer is mainly used for human-computer interaction, controlling the sequential angle slicing of the digital model, the movement of the motion modules, the serial and parallel operation of the projection modules, and monitoring the feedback behavior of the monitoring modules. The host computer can be a digital keypad, a touch screen, a computer, or other devices such as an industrial control computer.

[0069] Example 2

[0070] like Figure 4 As shown, this embodiment discloses a printing flowchart of a multi-material large-size volume 3D printing method. (As...) Figure 4 As shown, a method for large-volume 3D printing using multiple materials includes the following steps:

[0071] S1. Establish a three-dimensional digital model of the target sample, set it as an STL format file, slice it according to a layer thickness of 50 micrometers, and then convert it into a series of angle projections through tomographic projection algorithm and reverse tomographic projection algorithm. After image filtering, set the negative numbers of the numerical matrix in the angle projection to 0 or subtract the minimum value in the matrix. Use the projection module to input to DMD chips in different parts. When a single DMD chip is insufficient to meet the actual projection size, the control module can adaptively coordinate the splicing of the projection sequence by adjacent DMD chips, thereby improving the printable size.

[0072] S2. Two photosensitive resins with different photosensitive wavelengths are uniformly mixed with additive phases. The additive phase can be functional materials such as conductive particles, magnetic particles, and temperature and humidity sensitive particles. These additive phases can endow the printed structure with functional characteristics such as conductivity, magnetism, and light guiding. Before printing, the mixed photosensitive material needs to be placed in the air away from light for a period of time or a free radical scavenger needs to be added before adding it to the molding cavity 600. The two photosensitive resins with different photosensitive wavelengths operate in the 300nm-600nm range, corresponding to two projection modules respectively.

[0073] S3. Turn on the auxiliary module 800 and adjust the gas environment, temperature, and lighting conditions in the molding cavity 600 to the standard state. The temperature in the molding cavity 600 is 25℃ to avoid the cross-linking and curing of the photosensitive resin due to excessively high or low temperatures, and to prevent other light from entering and affecting the photopolymerization reaction of the projection module.

[0074] S4. Activate the motion module. The rotating platform drives the projection module and monitoring module to rotate uniformly around the center of the forming cavity 600. Their relative positions remain constant during movement. The rotation speed is 25-100° / s; a higher rotation speed promotes consistent curing of the printed structure. The XY displacement stage moves the projection system in the XY direction, and the Z-axis displacement stage moves the forming cavity 600 in the Z-axis direction. After one stage of printing is completed, the forming cavity 600 can move along the Z-axis to proceed to the next stage, expanding the printed size in the Z-axis direction.

[0075] S5. Activate the projection module. The projection system projects the serialized angle onto the forming cavity 600, forming a three-dimensional spatial energy accumulation in the target area. Once the energy exceeds the solidification threshold, the target entity is formed as a single unit.

[0076] S6. Activate the monitoring module. During the printing process, monitor the printing completion rate. The control module 900 reconstructs a 3D model from the real-time images of the printing process and compares it with the target model. The difference is compensated in the subsequent projection. When the completion rate reaches 100%, the printing proceeds to the next stage.

[0077] S7. Control module 900 determines whether printing along the Z-axis needs to continue. If printing continues, repeat stages S4-S7. If printing is complete, proceed to the next stage.

[0078] S8. Turn off the projection module, motion module, monitoring module, and other modules.

[0079] S9. Remove the printed material from the molding cavity 600, clean it with isopropyl alcohol in an ultrasonic cleaner, and then perform post-curing treatment in a post-curing chamber.

[0080] The rotation period of the projection module should be consistent with the period of the projection sequence to ensure the accuracy of spatial dose establishment in a single period.

[0081] The two photosensitive resins with different photosensitive wavelengths are a cationic photosensitive resin and a free radical photosensitive resin, respectively. The two polymer networks are formed through two independent mechanisms, resulting in a composite structure with highly tunable mechanical properties.

[0082] In this embodiment, the printed photosensitive resin has high transmittance in the visible light band, and the curing of one resin does not affect the specific dose accumulation of another resin cured by a different mechanism, thus ensuring the dimensional accuracy of multi-material printing.

[0083] The adjustability of the mechanical properties of the multi-material depends on the influence of projection light doses at different wavelengths. By controlling the dose ratio, the degree of cross-linking reaction of resins at different photosensitive wavelengths can be achieved, and their elastic modulus parameters can be further adjusted.

[0084] The single-band projection dose P is calculated as follows:

[0085] P = (S1 + S2 + ... + SE) * Q

[0086] In the formula,

[0087] S1, S2, SE are respectively Figure 2 DMD projection dose at different locations,

[0088] Q is the number of rotations of the projection module during the printing process and is an integer.

[0089] In this invention, each motion module can move arbitrarily, expanding the printing size in all directions. Since the printing cavity does not need to rotate, there is no relative movement between the photosensitive resin and the printing cavity, allowing for the printing of low-viscosity materials. In contrast, traditional equipment can only perform molding and printing in a fixed position, requiring the printing cavity to rotate. Therefore, if the resin viscosity is too low, the photosensitive resin inside the printing cavity will shake when the printing cavity rotates, resulting in poor printing quality.

[0090] Therefore, the multi-material large-size volume 3D printing method described above can solve the problems of small processing size, low printing flexibility, and high viscosity limitation of printing materials in current volume 3D printing.

[0091] In addition, the present invention also has the following effects:

[0092] 1. The present invention is equipped with a dual-light source projection system, which operates in different wavelength bands to cure photocurable resins with different physicochemical properties and manufacture composite performance parts.

[0093] 2. This invention utilizes DMD splicing technology to expand the projection area of ​​the projection system, and further expands the projection area by combining the projection orientation coordination between the two projection systems, thereby increasing the printable size of multi-material volume 3D printing technology.

[0094] 3. In this invention, the printing cavity can move in the Z-axis direction, which can further enable the Z-axis extension printing of the printed structure and further improve the printing size of multi-material volume 3D printing.

[0095] 4. The material system for 3D printing is further expanded by utilizing the rotation of the projection system. The static forming of the 600-degree forming cavity also increases the rotation speed of the projection system and improves the printing accuracy.

[0096] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A multi-material, large-size 3D printing system, characterized in that, include: The substrate has an annular groove on its upper surface. The molding cavity (600) is located at the center of the annular groove on the substrate and is used to support the printing substrate and the printing target structure. There are four turntables that are slidably engaged in an annular groove. The four turntables are divided into two groups, and the two turntables in each group are symmetrically distributed with the center of the annular groove as the point. The projection module has two components, each projecting two different photosensitive wavelengths, and is distributed on two turntables in the same group. The projection module includes a projection system, which moves vertically and horizontally relative to the turntable. The two projection systems project onto the same molding cavity (600). There are two monitoring modules, which are distributed on two turntables in another group. The monitoring modules move vertically relative to the turntables and are used to monitor the printing process. They transmit real-time printing information to the control module for analysis and real-time light dose correction. The motion module is used to control the synchronous movement of the projection module and the monitoring module in the same group; The motion module controls the two projection modules in the same group to move in a point-symmetric manner on both the horizontal and vertical planes. The micromirror unit of the projection system has multiple flip angles in multiple directions, with a flip angle of ±12°, so as to deliver the sequential angle projection energy to the same molding cavity (600). The projection system is composed of multiple DMD chips spliced ​​together, and the micromirror spacing of a single DMD chip is 13.68μm or 5.4μm; The two projection modules operate in low-band projection and high-band projection bands, respectively, and can be connected in series or in parallel. They are also designed for printing with two different photosensitive resins with different photosensitive bands. The two polymer networks are formed through two independent mechanisms to form a composite structure with highly adjustable mechanical properties. It also includes a control module (900), which coordinates and controls the projection module, motion module, monitoring module, molding cavity and auxiliary module (800). The motion module controls two projection modules in the same group to move symmetrically on the horizontal plane and simultaneously move up and down on the vertical plane.

2. The multi-material large-size volume 3D printing system as described in claim 1, characterized in that: The center of the annular groove of the substrate is provided with a Z-axis displacement stage (500) that can be raised and lowered, and the molding cavity (600) is connected to the Z-axis displacement stage (500).

3. The multi-material large-size volume 3D printing system as described in claim 1, characterized in that: The monitoring module includes a CCD camera (400c), an auxiliary observation light source (300c), an optical path system, and a data transmission component. The auxiliary observation light source (300c) operates in the red light band and does not affect the printing process. The monitoring module is installed on the lead screw slide to monitor the printing process, transmit real-time printing information to the control module for analysis, perform real-time illumination dose correction, and improve printing accuracy.

4. The multi-material large-size volume 3D printing system as described in claim 1, characterized in that: The sidewall transparency of the molding cavity (600) is greater than 90%.

5. The multi-material large-size volume 3D printing system as described in claim 1, characterized in that: It also includes an auxiliary module (800), which includes an oxygen content regulator, a humidity regulator, and a temperature regulator, used to adjust the oxygen content, temperature, humidity, and light intensity of the molding cavity to a standard state.

6. A printing method for a multi-material, large-size 3D printing system, characterized in that: The multi-material large-size volume 3D printing system as described in any one of claims 1-5 includes the following steps: S1. Establish a three-dimensional digital model of the target sample, convert it into a series of angle projections through tomographic projection algorithm and reverse tomographic projection algorithm, and then set the negative number of the numerical matrix in the angle projection to 0 or subtract the minimum value in the matrix at the same time, and input it into the DMD chip in different parts. S2. Two photosensitive resins with different photosensitive wavelengths are uniformly mixed with an additive phase, which is a conductive particle, a magnetic particle, or a temperature and humidity sensitive particle. Before printing, the mixed photosensitive material needs to be placed in the air away from light for a period of time or a free radical scavenger needs to be added before it is added to the molding cavity. The two photosensitive resins with different photosensitive wavelengths operate in the 300nm-600nm range, corresponding to two projection modules respectively. S3. Turn on the auxiliary module (800), adjust the gas environment, temperature and lighting conditions in the molding cavity to the standard state, the temperature in the molding cavity is 25℃, and no other light enters to affect the photopolymerization reaction of the projection module; S4. Activate the motion module. The rotating platform drives the projection module and monitoring module to rotate around the center of the forming cavity at a speed of 25-100° / s. The XY displacement stage can drive the projection system to move in the XY direction, and the Z-axis displacement stage (500) can drive the forming cavity to move in the Z-axis direction. After printing one stage, the forming cavity can move along the Z-axis direction to print the next stage, expanding the printing size in the Z-axis direction. S5. Activate the projection module. The projection system projects the serialized angle onto the molding cavity, forming a three-dimensional spatial energy accumulation in the target area. Once the energy exceeds the solidification threshold, the target entity is integrally formed. S6. Start the monitoring module to monitor the printing completion rate during the printing process. The control module (900) will reconstruct a three-dimensional model from the real-time image of the printing process and compare it with the target model. The difference will be compensated in the subsequent projection. When the completion rate reaches 100%, the printing will proceed to the next stage. S7. The control module (900) determines whether printing along the Z-axis needs to continue. If printing continues, the S4-S7 stages are repeated. If printing is completed, the next stage is performed. S8. Turn off the projection module, motion module, and monitoring module; S9. Remove the printed material from the molding cavity and perform post-curing treatment in the post-curing chamber.

7. The printing method of a multi-material large-size volume 3D printing system as described in claim 6, characterized in that: The two photosensitive resins with different photosensitive wavelengths are cationic photosensitive resin and free radical photosensitive resin, respectively.

Images