3D printing rapid prototyping method based on photocuring three-dimensional prototyping technology

Abstract

The invention discloses a 3D printing rapid prototyping method based on a photocuring three-dimensional prototyping technology, and relates to the technical field of 3D printing. Photosensitive resin composed of a resin matrix, a photoinitiator and a filler is used as a core material for photocuring 3D printing; performing three-dimensional model design on the printing sample; checking and repairing the model file in the stereolithography format, and judging whether the printing sample model has an error problem or not; printing parameters are set in the slicing software, and a detachable supporting structure is designed through a seed filling algorithm and used for supporting a suspended or inclined part; the light source system irradiates the photosensitive resin in the resin tank layer by layer based on a printing sample model preset instruction; the detachable supporting structure is removed; and carrying out surface grinding, polishing, spraying and curing treatment on the to-be-treated 3D model. A detachable supporting structure is designed through a seed filling algorithm, and the stability and integrity of the model in the printing process are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a 3D printing rapid prototyping method based on photocuring stereo molding technology. Background Art

[0002] 3D printing technology, also known as additive manufacturing, is a method of manufacturing objects layer by layer under computer control. 3D printing is different from traditional mold manufacturing methods. It is a process of dividing the entire model into n layers and printing them layer by layer. Each layer is based on the accumulation of the previous layer. For suspended and bridge structures, support is absolutely necessary. It is the key to maintaining the physical balance of 3D printed objects. Support structure is also an important factor in balancing internal stress and conducting heat. Especially in metal 3D printing, support structure is a key part to ensure printing stability and avoid warping and collapse.

[0003] The design of support algorithms needs to take into account multiple goals, such as ensuring the stability of printed parts, reducing the consumption of support materials, reducing the difficulty of removing supports, and maintaining the smoothness of the surface of printed parts. There are often conflicts between these goals, which makes the algorithm design complicated. With the development of 3D printing technology, the complexity and size of prints continue to increase, which puts higher requirements on the computational efficiency and accuracy of support algorithms. The algorithm needs to generate a reasonable support structure in a short time while ensuring the accuracy and stability of the support structure. However, existing support algorithms still have shortcomings in computational efficiency and accuracy, especially when dealing with large or complex models, which may require longer computing time and higher computing resources. Summary of the invention

[0004] In order to solve the above technical problems, a 3D printing rapid prototyping method based on photo-stereolithography technology is provided. This technical solution solves the problems raised in the above background technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is: A 3D printing rapid prototyping method based on photo-stereolithography technology, comprising: Photosensitive resin composed of resin matrix, photoinitiator and filler is used as the core material of photocuring 3D printing; Design a three-dimensional model of the printed sample and save the printed sample model in a stereolithography format that supports light-curing 3D printing; Check and repair the model file in the stereolithography format to determine whether there is an error problem in the printed sample model. If so, redesign the three-dimensional model of the printed sample. If not, no output is made. The error problems include isolated vertices, non-manifold edges and non-manifold faces. Setting printing parameters in the slicing software and using a seed filling algorithm to design a detachable support structure for supporting the suspended or inclined parts, wherein the printing parameters include layer thickness, filling rate, exposure time and light intensity; During the printing process, the light source system irradiates the photosensitive resin in the resin tank layer by layer based on the preset instructions of the printing sample model to obtain the 3D model to be processed; After printing is completed, the 3D model to be processed is taken out from the printer, the detachable support structure therein is removed, and the 3D model to be processed is cleaned to remove the uncured resin remaining on the surface; After cleaning, the 3D model to be processed is subjected to surface grinding, polishing, spraying and curing treatment to obtain a printed model.

[0006] Preferably, the photosensitive resin composed of a resin matrix, a photoinitiator and a filler as a core material for photocuring 3D printing specifically includes: When ultraviolet light irradiates the resin surface, the photoinitiator absorbs light energy to produce active fragments, which trigger the polymerization reaction of the prepolymer and active diluent in the resin matrix, causing the liquid resin to gradually solidify; Prepolymer is the basic skeleton of the photocurable product, which determines the basic properties of the cured product, including mechanical properties, physical and chemical properties and high temperature resistance; The reactive diluent adjusts the viscosity of the photosensitive resin so that the photosensitive resin can be evenly covered on the cured layer during the printing process; The photoinitiator absorbs ultraviolet light of a preset wavelength, transitions from a ground state to an active excited state, and initiates active fragments of monomer polymerization, wherein the active fragments include free radicals and cations; Nano-ceramic powder is added as filler to photosensitive resin to improve the strength and heat resistance of the printed material.

[0007] Preferably, the three-dimensional model design of the printing sample and saving the printing sample model in a stereolithography format supporting light-curing 3D printing specifically includes: Use computer-aided design software to create three-dimensional models of printed samples; Based on the three-dimensional model of the printed sample, information on vertices, normals and texture coordinates in the three-dimensional model is obtained and stored; The three-dimensional model of the printed sample is triangulated on the surface using the information of vertices, normals and texture coordinates, and a model file in a stereolithography format consisting of triangular meshes is obtained.

[0008] Preferably, the checking and repairing of the model file in the stereolithography format to determine whether an error occurs in the printed sample model specifically includes: Check along the surface and edges of the printed sample model; Determine whether there is a vertex that is not connected to other points, lines and faces. If so, output the point as an isolated vertex. If not, do not output it. Eliminate the geometric data of isolated vertices in the printed sample model; Check the connection relationship between the edges and faces in the printed sample model; Determine whether the number of faces connected by each edge in the printed sample model is not 2. If so, output the edge as a non-manifold edge. If not, do not output it. Determine whether the number of faces connected by the non-manifold edge is greater than 2. If so, delete the wrong connection relationship and only keep two connection relationships. If not, thicken the faces connected by the non-manifold edge and convert the non-manifold edge into a narrow plane. Determine the location of non-manifold surfaces by checking the boundaries and adjacency of all surfaces in the printed sample model; For non-manifold surfaces with discontinuous boundaries, the boundaries are repaired by adding or adjusting edges to form a continuous closed curve; For overlapping or intersecting non-manifold faces, the position and shape of the face are re-adjusted so that it connects correctly with adjacent elements.

[0009] Preferably, setting printing parameters in the slicing software and using a seed filling algorithm to design a detachable support structure for supporting the suspended or inclined part specifically includes: S101: Preset printing parameters in the slicing software; S102: The seed filling algorithm traverses the entire printed sample model to find all triangular facets that need support, and the angle between the normal vector of the triangular facet and the positive direction of the Z axis is greater than a preset angle threshold; S103: among the identified triangular facets that need support, the seed filling algorithm selects the triangular facet with the largest area that is not included in the support face set as a seed, and adds it to the support face set; S104: Starting from the seed, the seed filling algorithm gradually expands to the surrounding area, and adds the triangular facets that are adjacent to the seed and need support to the support face set, until all the triangular facets that are connected to the seed and need support are traversed; S105: Determine whether there are no triangular facets that need to be supported and are not classified into the supporting face set. If so, no output is made. If not, return to step S103. S106: assigning a unique identifier to each supporting surface, and storing these identifiers in a hash table, where the key of the hash table is the identifier of the supporting surface, and the value of the hash table is a set of triangular facets associated with the supporting surface; S107: Look up the identifier of each supporting surface and determine whether the value of its corresponding hash table is greater than a preset threshold. If so, support the supporting surface using a grid support method; if not, support the supporting surface using a tree support method.

[0010] Preferably, during the printing process, the light source system irradiates the photosensitive resin in the resin tank layer by layer based on the preset instructions of the printing sample model, and obtaining the 3D model to be processed specifically includes: Turn on the power of the light-curing 3D printer and preheat the laser; The stereolithography format file of the printed sample model is input into the light-curing 3D printer, and the light source system irradiates the photosensitive resin in the resin tank layer by layer according to the preset instructions; The laser beam scans according to the contour of each layer in the slice data, causing the photosensitive resin to undergo photocuring and cross-linking to form a layer of cured pattern; After the molding platform moves a layer height in the vertical direction, the light source system continues to irradiate the next layer of photosensitive resin; As the number of layers increases and the supporting structure is generated, the hash table is updated in real time; Add new support surfaces using a seed filling algorithm; Delete the processed support surface; Update the keys and values ​​of the hash table in real time.

[0011] Preferably, after the printing is completed, the 3D model to be processed is taken out from the printer, the detachable support structure therein is removed, and the 3D model to be processed is cleaned to remove the uncured resin remaining on the surface, which specifically includes: For the detachable tree-like support structure in the 3D model to be processed, use a knife to cut it; For the detachable lattice support structure in the 3D model to be processed, a mechanical cutting tool is used to remove it; Choose to use alcohol with a concentration of more than 95% as the cleaning solution; Soak the removed 3D model in the cleaning solution to soften and remove the uncured resin remaining on the surface; Use running distilled water to rinse the 3D model to be processed and rinse away the remaining cleaning liquid and resin; Use a high-pressure air gun to blow dry the 3D model to be processed.

[0012] Preferably, after the cleaning is completed, the surface of the 3D model to be processed is ground, polished, sprayed and cured to obtain a printed model, which specifically includes: Use coarse sandpaper to remove the unevenness and burrs on the surface of the 3D model to be processed; Use fine sandpaper to carefully polish the surface of the 3D model to be processed; Use polishing liquid to dissolve a layer of resin on the surface of the 3D model to be processed to form a smooth surface; Select a primer and spray it evenly on the surface of the 3D model to be processed; Select the topcoat and evenly spray it on the surface of the 3D model to be processed using a spray gun in a parallel movement manner; After spraying, place the 3D model to be processed in a constant temperature and humidity environment to dry naturally; Place the 3D model to be processed under UV light for curing.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The material system has the characteristics of fast curing speed, low curing shrinkage and excellent mechanical properties. The model files in stereolithography format are comprehensively checked and repaired, which effectively avoids the occurrence of errors such as isolated vertices, non-manifold edges and non-manifold faces, thereby improving the accuracy and success rate of printing. The seed filling algorithm is used to design a detachable support structure, which effectively supports the suspended or inclined parts and ensures the stability and integrity of the model during the printing process. At the same time, the detachable support structure is also convenient for subsequent processing and removal. The post-processing process not only improves the surface quality and mechanical properties of the printed parts, but also enhances their durability and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of the 3D printing rapid prototyping method based on the photo-stereolithography technology of the present invention; Figure 2 This is a flow chart of the core material composition method of the light-curing 3D printing of the present invention; Figure 3 A flow chart of a method for designing a three-dimensional model of a printed sample according to the present invention; Figure 4 A flow chart of a method for checking and repairing a model file in a stereolithography format according to the present invention; Figure 5 A flow chart of a part of the method for designing a detachable support structure for supporting a suspended or tilted structure by using a seed filling algorithm of the present invention; Figure 6 It is a flow chart of a method for the light source system of the present invention to irradiate the photosensitive resin in the resin tank layer by layer based on the preset instructions of the printing sample model; Figure 7 A flow chart of a method for removing a detachable support structure and cleaning a 3D model to be processed according to the present invention; Figure 8 This is a flow chart of the method for surface grinding, polishing, spraying and curing of a 3D model to be processed according to the present invention. DETAILED DESCRIPTION

[0015] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0016] Reference Figure 1 As shown, a 3D printing rapid prototyping method based on photo-stereolithography technology comprises: Photosensitive resin composed of resin matrix, photoinitiator and filler is used as the core material of photocuring 3D printing; Design a three-dimensional model of the printed sample and save the printed sample model in a stereolithography format that supports light-curing 3D printing; Check and repair the model file in the stereolithography format to determine whether there is an error problem in the printed sample model. If so, redesign the three-dimensional model of the printed sample. If not, no output is made. The error problems include isolated vertices, non-manifold edges and non-manifold faces. Setting printing parameters in the slicing software and using a seed filling algorithm to design a detachable support structure for supporting the suspended or inclined parts, wherein the printing parameters include layer thickness, filling rate, exposure time and light intensity; During the printing process, the light source system irradiates the photosensitive resin in the resin tank layer by layer based on the preset instructions of the printing sample model to obtain the 3D model to be processed; After printing is completed, the 3D model to be processed is taken out from the printer, the detachable support structure therein is removed, and the 3D model to be processed is cleaned to remove the uncured resin remaining on the surface; After cleaning, the 3D model to be processed is subjected to surface grinding, polishing, spraying and curing treatment to obtain a printed model.

[0017] As shown in FIG2 , the photosensitive resin composed of a resin matrix, a photoinitiator and a filler as the core material of light-curing 3D printing specifically includes: When ultraviolet light irradiates the resin surface, the photoinitiator absorbs light energy to produce active fragments, which trigger the polymerization reaction of the prepolymer and active diluent in the resin matrix, causing the liquid resin to gradually solidify; Prepolymer is the basic skeleton of the photocurable product, which determines the basic properties of the cured product, including mechanical properties, physical and chemical properties and high temperature resistance; The reactive diluent adjusts the viscosity of the photosensitive resin so that the photosensitive resin can be evenly covered on the cured layer during the printing process; The photoinitiator absorbs ultraviolet light of a preset wavelength, transitions from a ground state to an active excited state, and initiates active fragments of monomer polymerization, wherein the active fragments include free radicals and cations; Nano-ceramic powder is added as filler to photosensitive resin to improve the strength and heat resistance of the printed material.

[0018] The resin matrix usually contains prepolymers and reactive diluents. Prepolymers have photosensitive groups or are doped with photosensitive resins. They are important components in the resin system and mainly affect the photocuring rate of the resin and the various properties of the product. Reactive diluents have the function of diluting and adjusting the viscosity of the system and participate in the photocuring reaction. Photoinitiators are one of the most important components in the photocuring system because they are related to whether the resin system can generate free radicals when irradiated by light to successfully initiate the rapid cross-linking reaction and curing of oligomers.

[0019] As shown in FIG3 , the three-dimensional model design of the printing sample and the saving of the printing sample model in a stereolithography format supporting light-curing 3D printing specifically include: Use computer-aided design software to create three-dimensional models of printed samples; Based on the three-dimensional model of the printed sample, information on vertices, normals and texture coordinates in the three-dimensional model is obtained and stored; The three-dimensional model of the printed sample is triangulated on the surface using the information of vertices, normals and texture coordinates, and a model file in a stereolithography format consisting of triangular meshes is obtained.

[0020] The stereolithography format describes a raw unstructured triangular mesh consisting of surface unit normals and vertices ordered by the right-hand rule using a three-dimensional Cartesian coordinate system. Stereolithography format coordinates must be positive, have no scale information, and are measured in arbitrary units.

[0021] As shown in FIG4 , the model file in stereolithography format is checked and repaired to determine whether there is an error in the printed sample model. The specific problems include: Check along the surface and edges of the printed sample model; Determine whether there is a vertex that is not connected to other points, lines and faces. If so, output the point as an isolated vertex. If not, do not output it. Eliminate the geometric data of isolated vertices in the printed sample model; Check the connection relationship between the edges and faces in the printed sample model; Determine whether the number of faces connected by each edge in the printed sample model is not 2. If so, output the edge as a non-manifold edge. If not, do not output it. Determine whether the number of faces connected by the non-manifold edge is greater than 2. If so, delete the wrong connection relationship and only keep two connection relationships. If not, thicken the faces connected by the non-manifold edge and convert the non-manifold edge into a narrow plane. Determine the location of non-manifold surfaces by checking the boundaries and adjacency of all surfaces in the printed sample model; For non-manifold surfaces with discontinuous boundaries, the boundaries are repaired by adding or adjusting edges to form a continuous closed curve; For overlapping or intersecting non-manifold faces, the position and shape of the face are re-adjusted so that it connects correctly with adjacent elements.

[0022] An isolated vertex refers to a single vertex that is not connected to any edge or face in the model. In a three-dimensional model, a vertex is one of the basic elements that constitute the model. It is usually connected to each other through edges and faces to form a continuous geometric structure. The existence of isolated vertices will destroy the integrity of the model and may cause problems in subsequent processing (such as 3D printing, rendering, etc.). A non-manifold edge refers to an edge that does not conform to the definition of manifold geometry, and a non-manifold face refers to a face in the model that does not meet the manifold topological conditions.

[0023] As shown in Figure 5, the printing parameters are set in the slicing software, and the seed filling algorithm is used to design a detachable support structure to support the suspended or inclined parts, including: S101: Preset printing parameters in the slicing software; S102: The seed filling algorithm traverses the entire printed sample model to find all triangular facets that need support, and the angle between the normal vector of the triangular facet and the positive direction of the Z axis is greater than a preset angle threshold; S103: among the identified triangular facets that need support, the seed filling algorithm selects the triangular facet with the largest area that is not included in the support face set as a seed, and adds it to the support face set; S104: Starting from the seed, the seed filling algorithm gradually expands to the surrounding area, and adds the triangular facets that are adjacent to the seed and need support to the support face set, until all the triangular facets that are connected to the seed and need support are traversed; S105: Determine whether there are no triangular facets that need to be supported and are not classified into the supporting face set. If so, no output is made. If not, return to step S103. S106: assigning a unique identifier to each supporting surface, and storing these identifiers in a hash table, where the key of the hash table is the identifier of the supporting surface, and the value of the hash table is a set of triangular facets associated with the supporting surface; S107: Look up the identifier of each supporting surface and determine whether the value of its corresponding hash table is greater than a preset threshold. If so, support the supporting surface using a grid support method; if not, support the supporting surface using a tree support method.

[0024] Tree supports are known for their branch-like structures, which can provide sufficient support while minimizing the contact area with the model body. This support structure is easy to disassemble and causes less damage to the model body. However, tree supports may require more materials and time to print. Lattice supports are the simplest and most direct type of support. They consist of a series of columns perpendicular to the printing platform, directly supporting suspended or inclined parts. Lattice supports are easy to print and disassemble, but may increase material consumption and leave larger support marks on the model.

[0025] As shown in FIG6 , during the printing process, the light source system irradiates the photosensitive resin in the resin tank layer by layer based on the preset instructions of the printing sample model, and obtains the 3D model to be processed, which specifically includes: Turn on the power of the light-curing 3D printer and preheat the laser; The stereolithography format file of the printed sample model is input into the light-curing 3D printer, and the light source system irradiates the photosensitive resin in the resin tank layer by layer according to the preset instructions; The laser beam scans according to the contour of each layer in the slice data, causing the photosensitive resin to undergo photocuring and cross-linking to form a layer of cured pattern; After the molding platform moves a layer height in the vertical direction, the light source system continues to irradiate the next layer of photosensitive resin; As the number of layers increases and the supporting structure is generated, the hash table is updated in real time; Add new support surfaces using a seed filling algorithm; Delete the processed support surface; Update the keys and values ​​of the hash table in real time.

[0026] A hash table, also called a hash table, is a data structure that directly accesses storage locations in memory based on a key. That is, it accesses records by calculating a function about the key value and mapping the required queried data to a location in the table, which speeds up the search. This mapping function is called a hash function, and the array that stores records is called a hash table.

[0027] As shown in FIG. 7 , after printing is completed, the 3D model to be processed is taken out from the printer, the detachable support structure therein is removed, and the 3D model to be processed is cleaned to remove the uncured resin remaining on the surface. Specifically, the steps include: For the detachable tree-like support structure in the 3D model to be processed, use a knife to cut it; For the detachable lattice support structure in the 3D model to be processed, a mechanical cutting tool is used to remove it; Choose to use alcohol with a concentration of more than 95% as the cleaning solution; Soak the removed 3D model in the cleaning solution to soften and remove the uncured resin remaining on the surface; Use running distilled water to rinse the 3D model to be processed and rinse away the remaining cleaning liquid and resin; Use a high-pressure air gun to blow dry the 3D model to be processed.

[0028] Choose alcohol with a concentration of more than 95% as the cleaning liquid. High-concentration alcohol can effectively soften and remove the uncured resin remaining on the surface of the model without corroding or damaging the model itself. Soak the removed 3D model in the cleaning liquid completely. The soaking time can be determined according to the amount of residual resin on the surface of the model and the degree of curing. It usually takes several minutes to tens of minutes to soak. During the soaking process, the cleaning liquid can be stirred appropriately to promote the softening and dissolution of the resin.

[0029] As shown in FIG8 , after cleaning, the 3D model to be processed is subjected to surface grinding, polishing, spraying and curing treatment, and the printed model obtained specifically includes: Use coarse sandpaper to remove the unevenness and burrs on the surface of the 3D model to be processed; Use fine sandpaper to carefully polish the surface of the 3D model to be processed; Use polishing liquid to dissolve a layer of resin on the surface of the 3D model to be processed to form a smooth surface; Select a primer and spray it evenly on the surface of the 3D model to be processed; Select the topcoat and evenly spray it on the surface of the 3D model to be processed using a spray gun in a parallel movement manner; After spraying, place the 3D model to be processed in a constant temperature and humidity environment to dry naturally; Place the 3D model to be processed under UV light for curing.

[0030] The role of the primer is to enhance the adhesion and hiding power of the topcoat, making the surface of the model more uniform and beautiful. During the spraying process, pay attention to controlling the distance, speed and spraying amount of the spray gun to ensure that the coating is uniform, without bubbles and leaks.

[0031] Furthermore, the present solution also proposes a computer-readable storage medium on which a computer-readable program is stored. When the computer-readable program is called, the above-mentioned 3D printing rapid prototyping method based on photo-stereolithography technology is executed.

[0032] It is understandable that the storage medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; an optical medium, such as a DVD; or a semiconductor medium, such as a solid state drive (SSD).

[0033] In summary, the advantages of the present invention are: the material system has the characteristics of fast curing speed, low curing shrinkage and excellent mechanical properties, and the model file in the stereolithography format is comprehensively checked and repaired, which effectively avoids the occurrence of errors such as isolated vertices, non-manifold edges and non-manifold faces, thereby improving the accuracy and success rate of printing. The seed filling algorithm is used to design a detachable support structure, which effectively supports the suspended or inclined parts and ensures the stability and integrity of the model during the printing process. At the same time, the detachable support structure is also convenient for subsequent processing and removal. The post-processing process not only improves the surface quality and mechanical properties of the printed part, but also enhances its durability and practicality.

[0034] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A 3D printing rapid prototyping method based on photo-stereolithography technology, characterized in that: include: Photosensitive resin composed of resin matrix, photoinitiator and filler is used as the core material of photocuring 3D printing; Design a three-dimensional model of the printed sample and save the printed sample model in a stereolithography format that supports light-curing 3D printing; Check and repair the model file in the stereolithography format to determine whether there is an error problem in the printed sample model. If so, redesign the three-dimensional model of the printed sample. If not, no output is made. The error problems include isolated vertices, non-manifold edges and non-manifold faces. Setting printing parameters in the slicing software and using a seed filling algorithm to design a detachable support structure for supporting the suspended or inclined parts, wherein the printing parameters include layer thickness, filling rate, exposure time and light intensity; During the printing process, the light source system irradiates the photosensitive resin in the resin tank layer by layer based on the preset instructions of the printing sample model to obtain the 3D model to be processed; After printing is completed, the 3D model to be processed is taken out from the printer, the detachable support structure therein is removed, and the 3D model to be processed is cleaned to remove the uncured resin remaining on the surface; After cleaning, the 3D model to be processed is subjected to surface grinding, polishing, spraying and curing treatment to obtain a printed model.

2. The 3D printing rapid prototyping method based on stereolithography technology according to claim 1, characterized in that: The photosensitive resin composed of a resin matrix, a photoinitiator and a filler as the core material of light-curing 3D printing specifically includes: When ultraviolet light irradiates the resin surface, the photoinitiator absorbs light energy to produce active fragments, which trigger the polymerization reaction of the prepolymer and active diluent in the resin matrix, causing the liquid resin to gradually solidify; Prepolymer is the basic skeleton of the photocurable product, which determines the basic properties of the cured product, including mechanical properties, physical and chemical properties and high temperature resistance; The reactive diluent adjusts the viscosity of the photosensitive resin so that the photosensitive resin can be evenly covered on the cured layer during the printing process; The photoinitiator absorbs ultraviolet light of a preset wavelength, transitions from a ground state to an active excited state, and initiates active fragments of monomer polymerization, wherein the active fragments include free radicals and cations; Nano-ceramic powder is added as filler to photosensitive resin to improve the strength and heat resistance of the printed material.

3. The 3D printing rapid prototyping method based on photo-stereolithography technology according to claim 2, characterized in that: The three-dimensional model design of the printing sample and saving the printing sample model in a stereolithography format supporting light-curing 3D printing specifically includes: Use computer-aided design software to create three-dimensional models of printed samples; Based on the three-dimensional model of the printed sample, information on vertices, normals and texture coordinates in the three-dimensional model is obtained and stored; The three-dimensional model of the printed sample is triangulated on the surface using the information of vertices, normals and texture coordinates, and a model file in a stereolithography format consisting of triangular meshes is obtained.

4. The 3D printing rapid prototyping method based on photo-stereolithography technology according to claim 3, characterized in that: The checking and repairing of the model file in the stereolithography format to determine whether an error occurs in the printed sample model specifically includes: Check along the surface and edges of the printed sample model; Determine whether there is a vertex that is not connected to other points, lines and faces. If so, output the point as an isolated vertex. If not, do not output it. Eliminate the geometric data of isolated vertices in the printed sample model; Check the connection relationship between the edges and faces in the printed sample model; Determine whether the number of faces connected by each edge in the printed sample model is not 2. If so, output the edge as a non-manifold edge. If not, do not output it. Determine whether the number of faces connected by the non-manifold edge is greater than 2. If so, delete the wrong connection relationship and only keep two connection relationships. If not, thicken the faces connected by the non-manifold edge and convert the non-manifold edge into a narrow plane. Determine the location of non-manifold surfaces by checking the boundaries and adjacency of all surfaces in the printed sample model; For non-manifold surfaces with discontinuous boundaries, the boundaries are repaired by adding or adjusting edges to form a continuous closed curve; For overlapping or intersecting non-manifold faces, the position and shape of the face are re-adjusted so that it connects correctly with adjacent elements.

5. The 3D printing rapid prototyping method based on photo-stereolithography technology according to claim 4, characterized in that: The step of setting printing parameters in the slicing software and using a seed filling algorithm to design a detachable support structure for supporting the suspended or inclined part specifically includes: S101: Preset printing parameters in the slicing software; S102: The seed filling algorithm traverses the entire printed sample model to find all triangular facets that need support, and the angle between the normal vector of the triangular facet and the positive direction of the Z axis is greater than a preset angle threshold; S103: among the identified triangular facets that need support, the seed filling algorithm selects the triangular facet with the largest area that is not included in the support face set as a seed, and adds it to the support face set; S104: Starting from the seed, the seed filling algorithm gradually expands to the surrounding area, and adds the triangular facets that are adjacent to the seed and need support to the support face set, until all the triangular facets that are connected to the seed and need support are traversed; S105: Determine whether there are no triangular facets that need to be supported and are not classified into the supporting face set. If so, no output is made. If not, return to step S103. S106: assigning a unique identifier to each supporting surface, and storing these identifiers in a hash table, where the key of the hash table is the identifier of the supporting surface, and the value of the hash table is a set of triangular facets associated with the supporting surface; S107: Look up the identifier of each support surface and determine whether the value of its corresponding hash table is greater than a preset threshold. If so, support the support surface using a grid support method; if not, support the support surface using a tree support method.

6. The 3D printing rapid prototyping method based on stereolithography technology according to claim 5, characterized in that: During the printing process, the light source system irradiates the photosensitive resin in the resin tank layer by layer based on the preset instructions of the printing sample model to obtain the 3D model to be processed, which specifically includes: Turn on the power of the light-curing 3D printer and preheat the laser; The stereolithography format file of the printed sample model is input into the light-curing 3D printer, and the light source system irradiates the photosensitive resin in the resin tank layer by layer according to the preset instructions; The laser beam scans according to the contour of each layer in the slice data, causing the photosensitive resin to undergo photocuring and cross-linking to form a layer of cured pattern; After the molding platform moves a layer height in the vertical direction, the light source system continues to irradiate the next layer of photosensitive resin; As the number of layers increases and the supporting structure is generated, the hash table is updated in real time; Add new support surfaces using a seed filling algorithm; Delete the processed support surface; Update the keys and values ​​of the hash table in real time.

7. The 3D printing rapid prototyping method based on photo-stereolithography technology according to claim 6, characterized in that: After the printing is completed, the 3D model to be processed is taken out from the printer, the detachable support structure therein is removed, and the 3D model to be processed is cleaned to remove the uncured resin remaining on the surface, which specifically includes: For the detachable tree-like support structure in the 3D model to be processed, use a knife to cut it; For the detachable lattice support structure in the 3D model to be processed, a mechanical cutting tool is used to remove it; Choose to use alcohol with a concentration of more than 95% as the cleaning solution; Soak the removed 3D model in the cleaning solution to soften and remove the uncured resin remaining on the surface; Use running distilled water to rinse the 3D model to be processed and rinse away the remaining cleaning liquid and resin; Use a high-pressure air gun to blow dry the 3D model to be processed.

8. The 3D printing rapid prototyping method based on stereolithography technology according to claim 7, characterized in that: After the cleaning is completed, the surface of the 3D model to be processed is ground, polished, sprayed and cured to obtain a printed model, which specifically includes: Use coarse sandpaper to remove the unevenness and burrs on the surface of the 3D model to be processed; Use fine sandpaper to carefully polish the surface of the 3D model to be processed; Use polishing liquid to dissolve a layer of resin on the surface of the 3D model to be processed to form a smooth surface; Select a primer and spray it evenly on the surface of the 3D model to be processed; Select the topcoat and evenly spray it on the surface of the 3D model to be processed using a spray gun in a parallel movement manner; After spraying, place the 3D model to be processed in a constant temperature and humidity environment to dry naturally; Place the 3D model to be processed under UV light for curing.

Images