Multi-material large-size volumetric 3D printing system and printing method

Abstract

A multi-material large-size volumetric 3D printing system and a printing method. The system comprises a substrate; a molding cavity (600); rotary tables; projection modules, wherein two projection modules are provided, and two projection systems implement projection on the same molding cavity (600); monitoring modules, wherein two monitoring modules are provided and used for transmitting real-time printing information to a control module (900) for analysis and performing real-time light exposure dosage correction; and a motion module used for controlling synchronous movement of the projection modules of the same group and the monitoring modules of the same group. The projection size of the projection systems is increased by using the DMD tiling technology, and the projection area is further increased by means of projection orientation coordination between the two projection systems, thereby increasing the printable size of the volumetric 3D printing technology; moreover, projection module light sources can be flexibly replaced, such that the present invention is suitable for synchronous curing of photosensitive resins based on multiple curing principles, thereby greatly improving the manufacturing efficiency and the printing size of multi-material volumetric 3D printing.

Description

A multi-material large-size volume 3D printing system and printing method Technical Field

[0001] The present invention relates to the field of 3D printing technology, and in particular to a multi-material large-scale volume 3D printing system and printing method. Background Art

[0002] Volumetric 3D printing, a novel photo-curing additive manufacturing technology, boasts ultra-high-speed manufacturing capabilities because it simultaneously prints all points in a target area. Unlike traditional layer-by-layer printing, it accumulates three-dimensional energy within the target area. Once the solidification threshold is reached, the target solid is formed into a single, integrated entity, thus avoiding the stair-step effect often seen in traditional 3D printing and improving the surface quality of the printed sample. Furthermore, the printing process requires no auxiliary supports, eliminating the post-processing process that can degrade surface quality and the difficulty in removing internal supports from hollow structures. Technical issues

[0003] However, current volumetric 3D printing uses a rotating transparent molding cavity, which generates centrifugal force. In order to reduce the relative sliding between the photosensitive resin and the molding cavity, a photosensitive resin with a higher viscosity must be used. On the other hand, when using a low-viscosity photocurable resin, the rotation speed of the resin tank will be limited, which can easily cause uneven energy accumulation in the target area and result in differential mechanical properties in the cured area. At present, the size of volumetric 3D printed samples is limited by the projection format of the projection system, which limits the further application of volumetric 3D printing. Therefore, increasing the printing size of volumetric 3D printing and expanding its adaptability to printing in low-viscosity material systems are current problems.

[0004] Multi-material parts are widely used in aerospace, biomedicine, smart electronics, and other fields because they combine the physical and chemical properties of multiple materials. However, current multi-material photocuring 3D printing suffers from low printing precision, insufficient automation and integration of the printing device, high costs, and complex processes, making it difficult to meet current industrial manufacturing needs. Furthermore, most photocuring multi-material structures are manufactured by stacking layers, making it impossible to combine materials with different properties on the same layer. This layered manufacturing approach also makes the printing process time-consuming and inefficient. Technical Solutions

[0005] A multi-material large-scale volume 3D printing system, comprising:

[0006] A base plate, the upper end surface of which is provided with an annular sliding groove;

[0007] The molding cavity is located at the center of the annular groove on the substrate and is used to carry the printing substrate and the printing target structure;

[0008] There are four turntables which are slidably engaged in the annular chute, and 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 chute;

[0009] There are two projection modules, each projecting two different light-sensitive bands. The modules are located on two turntables in the same group. The projection modules include a projection system that moves vertically and horizontally relative to the turntable. The two projection systems project onto the same molding cavity.

[0010] There are two monitoring modules, which are distributed on the two turntables of the other group. The monitoring modules move vertically relative to the turntables and are used to monitor the printing process, transmit real-time printing information to the control module for analysis, and perform real-time light dose correction;

[0011] The motion module is used to control the synchronous movement of the projection module and the monitoring module in the same group.

[0012] Furthermore, a Z-axis displacement stage capable of being raised and lowered is provided at the center of the annular slide groove of the substrate, and the molding cavity is connected to the Z-axis displacement stage.

[0013] Furthermore, the monitoring module includes a CCD camera, an auxiliary observation light source, an optical path system and a data transmission component. The working band of the auxiliary observation light source is in the red light band and has no effect on the printing process. The monitoring module is installed on the screw slide to monitor the printing process, transmit real-time printing information to the control module for analysis, perform real-time light dose correction, and improve printing accuracy.

[0014] Furthermore, the transparency of the side wall of the molding cavity is greater than 90%.

[0015] Furthermore, it also includes an auxiliary module, which includes an oxygen content regulator, a humidity regulator, and a temperature regulator, which are used to adjust the oxygen content, temperature, humidity, light intensity and other environmental information of the molding cavity to a standard state.

[0016] 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 link.

[0017] Furthermore, the motion module controls the two projection modules in the same group to move in a point-symmetrical manner on the horizontal plane and to move up and down simultaneously on the vertical plane.

[0018] 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 a flip angle in multiple directions, and the flip angle is ±12°, thereby realizing the transmission of serialized angle projection energy to the same molding cavity 600.

[0019] Furthermore, the projection system is composed of multiple DMD chips, and the micromirror pitch of a single DMD chip is 13.68 μm or 5.4 μm.

[0020] Furthermore, the projection power of the projection system is 0-50 mW / cm2.

[0021] Furthermore, the working bands of the two projection modules are low-band projection and high-band projection respectively, and can meet the requirements of series or parallel operation.

[0022] A printing method for a multi-material large-scale volume 3D printing system comprises the following steps:

[0023] S1. Create a 3D digital model of the target sample and convert it into an STL file. Slice the model according to a 50-micron layer thickness, then convert it into a series of angular projections using a tomographic projection algorithm and a reverse tomographic projection algorithm. After image filtering, set the negative values ​​in the angular projection matrix to 0 or subtract the minimum value from the matrix. This data is then fed into DMD chips at 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 increasing the printable size.

[0024] S2. Evenly mix two photosensitive resins with different photosensitive bands with an additive phase, which can be a functional material such as conductive particles, magnetic particles, or temperature and humidity sensitive particles. 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 is added, and then added to the molding cavity; the two photosensitive resins with different photosensitive bands have an operating band of 300nm-600nm, corresponding to the two projection modules respectively;

[0025] S3. Turn on 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°C, and no other light enters to affect the photopolymerization reaction of the projection module;

[0026] S4. The motion module is activated. The rotating platform drives the projection module and monitoring module to rotate at a constant speed around the center of the build cavity. The relative positions of the two modules remain unchanged during the movement. The rotation speed is 25-100° / s. The XY translation stage drives the projection system in the X and Y directions, and the Z-axis translation stage drives the build cavity in the Z-axis direction. After one printing stage is completed, the build cavity can be moved along the Z-axis direction for the next printing stage, expanding the Z-axis print size.

[0027] S5. The projection module is turned on. The projection system projects the sequenced angles onto the molding cavity, forming a three-dimensional spatial energy accumulation in the target area. When the energy exceeds the solidification threshold, the target entity is formed in an integrated manner.

[0028] S6. The monitoring module is turned on to monitor the printing completion during the printing process. The control module reconstructs a 3D model from the real-time image of the printing process and compares it with the target model. The difference in dose is replenished in the next projection. When the completion reaches 100%, the printing proceeds to the next stage.

[0029] S7. The control module determines whether to continue printing along the Z axis. If printing is continued, steps S4-S7 are repeated. If printing is complete, the next step is performed.

[0030] S8. Turn off the projection module, motion module, monitoring module and other modules;

[0031] S9. Remove the printed object from the molding cavity, clean it in an ultrasonic cleaner with isopropyl alcohol, and then perform post-curing in a post-curing box.

[0032] 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.

[0033] Furthermore, the projected light needs to be processed by a collimating lens and emitted horizontally to reduce energy loss and beam diffusion.

[0034] Furthermore, the two photosensitive resins with different photosensitive wavelengths are respectively a cationic photosensitive resin and a free radical photosensitive resin.

[0035] Furthermore, the two polymer networks are formed through two independent mechanisms, resulting in a composite structure with highly tunable mechanical properties.

[0036] Furthermore, the printed photosensitive resins all have high transmittance in the visible light band, and the curing of one resin will not affect the specific dose accumulation of another mechanism-cured resin, ensuring the dimensional accuracy of multi-material printing. Beneficial effects

[0037] The present invention has a simple structure and is easy to operate. Under the joint action of the two projection modules and the rotation of the molding cavity, large-scale printing can be achieved. At the same time, printing is performed on two 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, which is very practical.

[0038] 1. The present invention is equipped with a dual-light source projection system, which operates in different wavelength bands and is used to cure light-curable resins with different physical and chemical properties to manufacture composite performance parts.

[0039] 2. The present invention utilizes DMD splicing technology to expand the projection format of the projection system, and then combines the projection orientation coordination between the dual projection systems to further expand the projection area, thereby increasing the printable size of the multi-material volume 3D printing technology.

[0040] 3. The printing chamber in the present invention can move in the Z-axis direction, which can further realize the Z-axis extension printing of the printed structure, further improving the printing size of multi-material volume 3D printing.

[0041] 4. The rotation of the projection system is used to further expand the material system of volume 3D printing. The static molding of the molding cavity also increases the rotation speed of the projection system and improves the printing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a schematic diagram of the three-dimensional structure of the present invention.

[0043] FIG2 is a schematic diagram of DMD splicing according to the present invention.

[0044] FIG3 is a schematic diagram of the relative positions of the projection system of the present invention;

[0045] FIG4 is a flow chart of multi-material large-scale volume 3D printing according to the present invention. Modes for Carrying Out the Invention

[0046] Example 1

[0047] Figure 1 is a schematic diagram of the 3D printing system structure of an embodiment of a multi-material large-scale volume 3D printing system and printing method of the present invention, which includes a substrate, a molding cavity 600, a turntable, a projection module, a monitoring module and a motion module. Under the joint action of two projection modules, coordinated with the rotation of the molding cavity 600, large-scale printing can be achieved. At the same time, printing is performed on two photosensitive resins with different photosensitive bands. Two polymer networks are formed through two independent mechanisms to form a composite structure with highly adjustable mechanical properties, which is very practical.

[0048] The substrate in this embodiment serves as a carrier for the entire device, and its upper end surface is horizontally arranged and has an annular sliding groove;

[0049] The molding cavity 600 is used to carry the printing substrate and the printing target structure. The molding cavity 600 is located at the center of the annular groove on the substrate. At the same time, a Z-axis translation stage 500 that can be raised and lowered is provided at the center of the annular groove of the substrate. The molding cavity 600 is connected to the Z-axis translation stage 500. In order to ensure the accuracy of three-dimensional energy transmission, it should have a transparency of more than 90% in the projection working band.

[0050] In this embodiment, there are four turntables, which are slidably engaged in the annular chute. The four turntables are divided into two groups. The two turntables in each group are point-symmetrically distributed with respect to the center of the annular chute. The point-symmetrical distribution also includes a line-symmetrical distribution, that is, they can be distributed face to face or tilted relative to each other on the horizontal plane to increase the projection range.

[0051] In this embodiment, there are two projection modules, each projecting two different wavelength bands. The modules are located on two turntables in the same group and can work in series or in parallel. The projection modules include a projection system that moves vertically and horizontally relative to the turntable. The two projection systems project onto the same molding cavity 600.

[0052] The projection module in this embodiment is installed on the screw slide (screw slide 100a, screw slide 200a), and is composed of two identical projection systems (projection system 1 100b, projection system 2 200b). As shown in Figure 2, each projection system (projection system 100b, projection system 2 200b) is composed of multiple DMD chips. According to the different printing accuracy, the micro-mirror pitch size of a single DMD chip can be selected to be 13.68μm or 5.4μm. The micro-mirror pitch size is 13.68μm or 5.4μm. The smaller the distance value, the more conducive it is to improving the resolution of the printed structure. The micromirror unit of the projection system (projection system 1 100b, projection system 2 200b) has a flip angle in multiple directions, with a flip angle of ±12°. This allows the two projection systems (projection system 1 100b, projection system 2 200b) to illuminate the same molding cavity 600. As shown in Figure 3, by changing the relative positions of the dual projection systems, a large-area projection format can be achieved, and the serialized angle projection energy can be delivered to the molding cavity 600.

[0053] There are two monitoring modules in this embodiment, which are distributed on two turntables of another group. The monitoring modules move vertically relative to the turntable. The monitoring modules include a CCD camera 400c, an auxiliary observation light source 300c, an optical path system and a data transmission component. The working band of the auxiliary observation light source 300c is in the red light band and has no effect on the printing process. The monitoring module is installed on the screw slide and is used to monitor the printing process, transmit real-time printing information to the control module for analysis, perform real-time light dose correction, and improve printing accuracy.

[0054] 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.

[0055] Specifically, as shown in Figure 1, the motion module is used to control the screw slide (screw slide 1 100a, screw slide 2 200a, screw slide 3 300a, screw slide 4 400a), XY axis translation stage (XY axis translation stage 1 100c, XY axis translation stage 2 200c), bottom turntable (turntable 1 100d, turntable 2 200d) , turntable three 300b, turntable four 400b) and Z-axis translation stage 500 move, the screw slide drives the projection module and the monitoring module (XY-axis translation stage three 300c, CCD camera 400c) to rotate around the center, the screw slide (screw slide one 100a, screw slide two 200a) connected to the projection module is connected to the turntable (turntable one 100d, turntable two 200d) through the XY-axis translation stage (XY-axis translation stage one 100c, XY-axis translation stage two 200c), the monitoring module can be connected to the bottom turntable (turntable three 300b, turntable four 400b) through the screw slide (screw slide three 300a, screw slide four 400a), and the molding cavity 600 is connected to the bottom platform 700 through the Z-axis translation stage 500.

[0056] In this embodiment, specifically, the motion module controls the two projection modules in the same group to move in a point-symmetrical manner on the horizontal plane. The symmetrical serialized images obtained through the forward and reverse tomographic projection algorithms can be respectively transmitted to the two projection modules, which can further increase the light dose accumulation size of the target space and expand the single projection printing size. At the same time, the projection module can move up and down simultaneously on the vertical plane, and can realize selective curing of the molding cavity 600Z to any position.

[0057] In another embodiment, 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 a flip angle in multiple directions, and the flip angle is ±12°. When it flips +12°, the reflected light is imaged in the target area along the optical axis, forming a bright pixel. When the reflector deviates from the equilibrium position by -12°, the reflected light beam will not be projected on the target area, so a dark pixel appears. The periodic proportion of each state can adjust its projection grayscale value to realize the transmission of serialized angle projection energy to the same molding cavity 600, thereby achieving energy uniformity and printing synchronization in the target area. The projected light needs to be processed by a collimating mirror and emitted horizontally to reduce energy loss and beam diffusion.

[0058] 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 working band of the auxiliary observation light source 300c is in the red light band and has no effect on the printing process. The monitoring module is installed on the screw slide and is used to monitor the printing process, transmit real-time printing information to the control module for analysis, perform real-time light dose correction, and improve printing accuracy.

[0059] In another embodiment, in order 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 around 25°C, to avoid excessively high or low temperature affecting the cross-linking and curing of the photosensitive resin, the humidity is between 40%-70% to prevent static electricity from affecting the printing effect, and the light intensity is in a backlight environment to avoid other uncontrollable light affecting the printing of the target entity, thereby improving the controllability of the printing process.

[0060] In another embodiment, a control module 900 is further included. The control module 900 coordinates and controls the projection module, the motion module, the monitoring module, the molding cavity 600 and the auxiliary module 800 to ensure the automated and safe operation of each link and improve the intelligent effect.

[0061] 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 primarily used for human-computer interaction, controlling the serialized angle slices of the digital model, the movement of the motion module, the serial and parallel operation of the projection module, and feedback from the monitoring module. The host computer can be a digital keypad, a touch screen, a computer, or other devices such as an industrial computer.

[0062] Example 2

[0063] As shown in Figure 4, this embodiment discloses a printing flow chart of a multi-material large-scale volume 3D printing method. As shown in Figure 4, a multi-material large-scale volume 3D printing method includes the following steps:

[0064] S1. Build a three-dimensional digital model of the target sample and set it to an STL format file. First, slice it according to a layer thickness of 50 microns, and then convert it into a series of angle projections through the tomographic projection algorithm and the reverse tomographic projection algorithm. After image filtering, the negative numbers of the numerical matrix in the angle projection are set to 0 or the minimum value in the matrix is ​​subtracted at the same time. Use the projection module to input it to the DMD chips in different parts. When a single DMD chip is not enough to meet the actual projection size, the control module can adaptively coordinate the splicing of the projection sequence of adjacent DMD chips, thereby increasing the printable size.

[0065] 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. These additive phases can impart functional properties such as conductivity, magnetic conductivity, and light transmission to the printed structure. Before printing, the mixed photosensitive material must be placed in air in the dark for a period of time or a free radical scavenger must 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 the two projection modules.

[0066] S3. Turn on the auxiliary module 800 and adjust the gas environment, temperature, and lighting conditions in the molding cavity 600 to standard conditions. The temperature in the molding cavity 600 is at 25°C to avoid excessively high or low temperatures that affect the cross-linking and curing of the photosensitive resin, and no other light enters to affect the photopolymerization reaction of the projection module.

[0067] S4. The motion module is activated. The rotating platform drives the projection module and monitoring module to rotate at a constant speed around the center of the build chamber 600. The relative positions of the two modules remain unchanged during this rotation. The rotation speed is 25-100° / s. A higher rotation speed improves the consistency of the printed structure. The XY translation stage drives the projection system in the X and Y directions, while the Z-axis translation stage drives the build chamber 600 in the Z direction. After completing one printing stage, the build chamber 600 can be moved along the Z axis to proceed to the next printing stage, expanding the Z-axis print area.

[0068] S5. Turn on the projection module. The projection system projects the sequenced angles onto the molding cavity 600, forming a three-dimensional space energy accumulation in the target area. When the energy exceeds the solidification threshold, the target entity is formed in an integrated manner.

[0069] S6. The monitoring module is activated to monitor the print completion rate during the printing process. The control module 900 reconstructs a 3D model from the real-time images of the printing process and compares them with the target model. The difference in dose is replenished in the next projection. When the completion rate reaches 100%, the printing proceeds to the next stage.

[0070] S7. The control module 900 determines whether it is necessary to continue printing along the Z axis. If printing is to continue, the steps S4-S7 are repeated. If printing is completed, the next step is performed.

[0071] S8. Turn off the projection module, motion module, monitoring module and other modules.

[0072] S9. Take out the printed material from the molding cavity 600, clean it in an ultrasonic cleaning machine with isopropyl alcohol, and then perform post-curing treatment in a post-curing box.

[0073] 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.

[0074] The two photosensitive resins with different photosensitive wavelengths are a cationic photosensitive resin and a free radical photosensitive resin. The two polymer networks are formed through two independent mechanisms to form a composite structure with highly adjustable mechanical properties.

[0075] In this embodiment, the printed photosensitive resins all have high transmittance in the visible light band, and the curing of one resin will not affect the specific dose accumulation of another mechanism-cured resin, thereby ensuring the dimensional accuracy of multi-material printing.

[0076] The adjustability of the multi-material mechanical properties depends on the influence of the projection light dose in different bands. By controlling the dose ratio, the cross-linking reaction degree of resins in different photosensitive bands can be achieved, and the elastic modulus parameters can be further adjusted.

[0077] The single-band projection dose P is calculated as follows:

[0078] P=(S1+S2+…+SE)*Q

[0079] Where,

[0080] S1, S2, SE are the DMD projection doses at different positions in Figure 2,

[0081] Q is the number of rotations of the projection module during the printing process and is an integer.

[0082] In the present invention, each motion module can move arbitrarily, expanding the printing size in all directions. Since the printing cavity does not need to rotate, the photosensitive resin and the printing cavity do not move relative to each other, and low-viscosity materials can be printed. Traditional equipment can only perform molding printing at a fixed position and requires the printing cavity to rotate. Therefore, if the resin viscosity is too low, the photosensitive resin inside will shake when the printing cavity rotates, resulting in poor printing effect.

[0083] Therefore, the present invention adopts the above-mentioned multi-material large-scale volume 3D printing method to solve the current problems of volume 3D printing, such as small processing size, low printing flexibility, and high viscosity limitation of printing materials.

[0084] Simultaneously, the present invention also has the following effects:

[0085] 1. The present invention is equipped with a dual-light source projection system, which operates in different wavelength bands and is used to cure light-curable resins with different physical and chemical properties to manufacture composite performance parts.

[0086] 2. The present invention utilizes DMD splicing technology to expand the projection format of the projection system, and then combines the projection orientation coordination between the dual projection systems to further expand the projection area, thereby increasing the printable size of the multi-material volume 3D printing technology.

[0087] 3. The printing chamber in the present invention can move in the Z-axis direction, which can further realize the Z-axis extension printing of the printed structure, further improving the printing size of multi-material volume 3D printing.

[0088] 4. The rotation of the projection system is used to further expand the material system for volumetric 3D printing. The static molding of the molding cavity 600 also increases the rotation speed of the projection system and improves the printing accuracy.

[0089] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any modifications may be made within the scope of protection of the present invention.

Claims

1. A multi-material large-scale volume 3D printing system, characterized in that: include: A base plate, the upper end surface of which is provided with an annular sliding groove; A molding cavity (600) is located at the center of the annular slot on the substrate and is used to carry the printing substrate and the printing target structure; There are four turntables which are slidably engaged in the annular chute, and 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 chute; There are two projection modules, each projecting two wavelength bands with different photosensitive properties, and the modules are distributed on two turntables in the same group. The projection modules include a projection system, the projection system moves vertically and horizontally relative to the turntable, and the two projection systems project onto the same molding cavity (600); There are two monitoring modules, which are distributed on the two turntables of the other group. The monitoring modules move vertically relative to the turntables and are used to monitor the printing process, transmit real-time printing information to the control module for analysis, and perform 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.

2. The multi-material, large-scale volume 3D printing system according to claim 1, characterized in that: A Z-axis displacement stage (500) capable of being raised and lowered is provided at the center of the circular slide groove of the substrate, and the molding cavity (600) is connected to the Z-axis displacement stage (500).

3. The multi-material, large-scale volume 3D printing system according to claim 1, characterized in that: The monitoring module comprises 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 has no effect on the printing process. The monitoring module is mounted on a lead screw slide and is used to monitor the printing process, transmit real-time printing information to a control module for analysis, perform real-time light dose correction, and improve printing accuracy.

4. The multi-material, large-scale volume 3D printing system according to claim 1, characterized in that: The transparency of the side wall of the molding cavity (600) is greater than 90%.

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

6. A multi-material, large-scale volume 3D printing system according to any one of claims 1 to 5, characterized in that: The system further comprises a control module (900), which coordinates and controls the projection module, the motion module, the monitoring module, the molding cavity and the auxiliary module (800) to ensure the automated and safe operation of each link.

7. The multi-material large-scale volume 3D printing system according to claim 6, characterized in that: The motion module controls the two projection modules in the same group to move in a point-symmetrical manner on the horizontal plane and to move up and down simultaneously on the vertical plane.

8. The multi-material, large-scale volume 3D printing system according to claim 1, characterized in that: The motion module controls the two projection modules in the same group to move in a point-symmetrical manner on the horizontal and vertical planes. The micromirror unit of the projection system has a flip angle in multiple directions, and the flip angle is ±12°, so as to realize the transmission of serialized angle projection energy to the same molding cavity 600.

9. A multi-material, large-scale volume 3D printing system according to claim 7 or 8, characterized in that: The projection system is composed of multiple DMD chips, and the micromirror pitch of a single DMD chip is 13.68 μm or 5.4 μm.

10. The multi-material large-scale volume 3D printing system according to claim 9, characterized in that: The two projection modules operate in low-band projection and high-band projection bands respectively, and can operate in series or in parallel.

11. A printing method for a multi-material, large-scale volume 3D printing system, characterized by: The large-scale volume 3D printing system according to claim 10 comprises the following steps: S1. Build a 3D digital model of the target sample, convert it into a series of angular projections using a tomographic projection algorithm and a reverse tomographic projection algorithm, then set the negative values ​​in the angular projection matrix to 0 or subtract the minimum value from the matrix, and input it into the DMD chip at different locations; S2. Evenly mix two photosensitive resins with different photosensitive bands with an additive phase, which can be a functional material such as conductive particles, magnetic particles, or temperature and humidity sensitive particles. 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 is added, and then added to the molding cavity; the two photosensitive resins with different photosensitive bands have an operating band of 300nm-600nm, corresponding to the two projection modules respectively; S3. Turn on the auxiliary module (800), adjust the gas environment, temperature, and lighting conditions in the molding cavity to standard conditions, the temperature in the molding cavity is 25°C, and no other light enters to affect the photopolymerization reaction of the projection module; S4. Turn on the motion module, the rotating platform drives the projection module and the monitoring module to rotate around the center of the molding cavity, 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 (500) can drive the molding cavity to move in the Z-axis direction; after printing one stage, the molding cavity can move along the Z-axis direction to print the next stage, expanding the printing size in the Z-axis direction; S5. The projection module is turned on. The projection system projects the sequenced angles onto the molding cavity, forming a three-dimensional spatial energy accumulation in the target area. When the energy exceeds the solidification threshold, the target entity is formed in an integrated manner. S6. The monitoring module is turned on to monitor the printing completion during the printing process. The control module (900) reconstructs a three-dimensional model of the real-time image of the printing process and compares it with the target model. The difference dose is replenished in the next projection. When the completion reaches 100%, the printing proceeds to the next stage. S7. The control module (900) determines whether it is necessary to continue printing along the Z axis. If printing is continued, the steps S4-S7 are repeated. If printing is completed, the next step is performed. S8. Turn off the projection module, motion module, monitoring module and other modules; S9. Take out the printed object from the molding cavity and perform post-curing treatment in a post-curing box.

12. The printing method of a multi-material large-scale volume 3D printing system according to claim 11, characterized in that: The two photosensitive resins with different photosensitive wavelengths are respectively a cationic photosensitive resin and a free radical photosensitive resin.

13. The printing method of a multi-material large-scale volume 3D printing system according to claim 12, characterized in that: The two polymer networks are formed via two independent mechanisms, resulting in a composite structure with highly tunable mechanical properties.

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