A high-precision SLA light-curing 3D printing support structure design method

Abstract

The application relates to the technical field of additive manufacturing, in particular to a high-precision SLA light-curing 3D printing support structure design method.The technical scheme comprises the following steps: firstly, posture setting and layering slicing are performed on a three-dimensional model to be printed, and the contour of each layer and a support area are extracted; then, a layer peeling force prediction model is constructed in combination with characteristics, the peeling force field distribution of each layer and a local area is obtained, a mechanical conduction model is established by taking the support area as a load application point and a printing substrate as a constraint end, path optimization is performed by taking the peeling force field as a weight, a force flow conduction path network is generated from the support area to the substrate, the path network is further subjected to structural processing, a hierarchical support skeleton network is formed, and finally, three-dimensional printing data is output.The application realizes accurate arrangement and efficient bearing of the support structure by constructing a support design method driven by the peeling force, combining force flow path optimization and a hierarchical skeleton structure, reduces material consumption, reduces post-processing difficulty and improves product quality.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a high-precision SLA photopolymerization 3D printing support structure design method. Background Technology

[0002] SLA (Silicon Lamination) photopolymerization 3D printing technology has been widely used in precision models, medical devices, industrial prototypes, and jewelry due to its advantages such as high forming accuracy, good surface quality, and suitability for manufacturing complex curved structures. In actual printing, the model to be printed usually needs to be supported by a support structure to support suspended areas, slender structures, and local thin-walled areas to avoid warping, collapse, detachment, or printing failure during interlayer printing.

[0003] Current SLA support structure designs mostly rely on empirical parameters or simple geometric rules for layout. They typically determine the support position and quantity based solely on local overhang angles, contact areas, or manual experience. This makes it difficult to accurately reflect the distribution of peeling forces on different layers and areas during printing, resulting in significant problems such as discontinuities in the force transmission path, redundant supports, or insufficient local support. On the one hand, too few supports can easily lead to displacement, deformation, or even breakage of the model during peeling; on the other hand, too many supports or excessively strong contact increases the difficulty of post-processing removal, easily leaving obvious support marks on the model surface, affecting the finished product's appearance and dimensional accuracy.

[0004] Furthermore, traditional support structures are typically of uniform cross-section, single-level, or simple tree-like structure, lacking optimized design for the direction of peel force transmission. This results in low utilization of support materials and an inability to balance printing stability with ease of removal. If the contact point between the support and the model lacks buffering or controllable fracture design, the model surface is easily damaged during support removal, a problem particularly pronounced for delicate thin-walled parts, curved surfaces, and printing objects requiring high surface precision.

[0005] Therefore, there is an urgent need for a high-precision SLA photopolymerization 3D printing support structure design method that can optimize the support path and design the structure hierarchically based on the peeling force field, while also taking into account the easy removal performance. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the background technology by proposing a high-precision SLA photopolymerization 3D printing support structure design method.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a high-precision SLA photopolymerization 3D printing support structure design method, comprising the following steps: S1. Obtain the 3D model to be printed, set the pose of the model and slice it into layers, and extract the contours of each layer and the area to be supported. S2. Based on the cross-sectional area of ​​each layer, the interlayer normal angle and the adhesion characteristics of the photosensitive resin, a prediction model for interlayer peel force is constructed to obtain the peel force field distribution of each layer and local area of ​​the model. S3. Using the area to be supported as the load application point and the printed substrate as the constraint end, construct a mechanical transmission model based on the peeling force field; S4. In the mechanical transmission model, the peeling force field is used as the weight field, and a top-down path optimization calculation is performed to generate a force flow transmission path network from the area to be supported to the printed substrate. S5. The force flow transmission path network is structured to generate a hierarchical support skeleton network. The hierarchical support skeleton network includes main supports, secondary branches and end support units, and the path connection forms a continuous branching structure. S6. Generate and output 3D printing data based on the hierarchical support skeleton network for SLA photopolymerization molding.

[0008] Furthermore, the peel force prediction model in S2 includes at least resin interface adhesion force, delamination area, peel speed and local structural stiffness parameters, and the peak peel force function is obtained through experimental calibration.

[0009] Furthermore, the path optimization calculation in S4 satisfies the constraints that the overall path direction is opposite to the printing separation direction and the path curvature changes continuously. When the path network is generated, the area to be supported is discretized into multiple load points, and path search is performed with each load point as the starting point. When multiple paths intersect, they are merged to form a tree-like topology.

[0010] Furthermore, the cross-sectional parameters of the hierarchical support skeleton network in S5 satisfy the following: main support diameter Its branch diameter satisfy ,in .

[0011] Furthermore, in the hierarchical support skeleton network, the main supports are arranged along the main transmission direction of the peeling force, the secondary branches extend toward the area to be supported, and the distribution density of the end support units is positively correlated with the magnitude of the local peeling force.

[0012] Furthermore, a controlled brittle fracture structure is provided at the contact point between the end support unit and the model. The controlled brittle fracture structure includes a weak fracture zone and an outer force transmission zone. The cross-sectional size of the weak fracture zone is smaller than that of the force transmission zone, with a diameter of 0.2 mm to 0.6 mm and circumferential and radial notches. The depth of the notches is 10% to 30% of the cross-sectional size. The weak fracture zone is formed by locally reducing the exposure energy and reducing the cross-sectional area of ​​the structure, so that its fracture strength is lower than that of the surface strength of the model material.

[0013] Furthermore, a lattice buffer structure is provided at the contact end between the end support unit and the model. The lattice buffer structure is composed of periodic and non-periodic lattice units with a size of 0.05 mm to 0.5 mm and a relative density that varies in gradient from the contact center outwards, with the density at the contact center being 50% to 90% and the density at the outer side being 10% to 60%.

[0014] Furthermore, the hierarchical support skeleton network is subjected to a porous treatment, and a through channel is set inside the hierarchical support skeleton network to form a porous structure. The porosity of the porous structure is 60% to 90%, the outer shell thickness is 0.1 mm to 0.5 mm, the internal channel diameter is 0.2 mm to 1.0 mm, and the porosity gradually changes along the support height direction.

[0015] Furthermore, the model attitude is optimized before S1, and iterative adjustments are made with the goal of minimizing the peak peeling force and the support volume.

[0016] Furthermore, the method also includes a post-printing support removal step, wherein the support preferentially fractures at the controlled brittle fracture structure and is rapidly removed by solvent cleaning and ultrasonic treatment.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: By setting the posture of the 3D model to be printed, slicing it into layers, and predicting the peeling force, the distribution of the peeling force field between layers can be established, so that the support design is transformed from experience-driven to mechanical-driven, and the pertinence and accuracy of the support layout are improved. By constructing a mechanical transmission model and performing path optimization calculations, a force flow transmission path network from the area to be supported to the printing substrate can be generated, so that the support structure is arranged along the main force path, which enhances the efficiency of the support in transmitting peel load and improves printing stability. By structuring the path network into a hierarchical support skeleton network, forming main supports, secondary branches and end support units, differentiated load-bearing in different stress areas can be achieved, ineffective supports can be reduced, and the spatial adaptability and material utilization of the support structure can be improved. By designing the cross-sectional parameters of the main supports and branch supports, the gradual distribution of support strength can be achieved while ensuring the overall load-bearing capacity, reducing local stress concentration and improving structural reliability. By setting a controlled brittle fracture structure, the support can be made to fracture before the model body in the post-processing stage, reducing the pulling damage to the model surface when removing the support, and improving the support removal efficiency and finished product yield. By setting a lattice buffer structure in the end support unit, the stress impact at the contact end between the support and the model can be reduced, the contact stability can be improved, and local indentation and surface damage can be reduced. By making the support structure porous, the support volume and material consumption can be further reduced, while the peeling load during printing can be reduced, and the flow of cleaning media and post-processing residue removal can be facilitated. By optimizing the model's posture and iteratively adjusting it with the goals of minimizing the peak peeling force and the support volume, a balance can be achieved between forming success rate, support quantity, and post-processing difficulty, thereby comprehensively improving SLA printing efficiency and finished product quality. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the overall process of the method of the present invention. Figure 2 This is a block diagram of the mechanical transmission and path optimization logic of the present invention; Figure 3 The following is a logic block diagram for generating hierarchical support in this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figures 1-3 As shown, the present invention proposes a high-precision SLA photopolymerization 3D printing support structure design method, which includes the following steps: S1. Model preprocessing, pose setting and slicing First, a 3D model in STL / STEP format to be printed is constructed or imported using 3D modeling software. The model is then preprocessed to repair geometric defects such as non-manifold edges, holes, and overlapping surfaces, ensuring that the model is a watertight solid model.

[0021] In a preferred embodiment of the present invention, before setting the formal posture, the model printing posture is first set: with the dual optimization objectives of minimizing the peak value of interlayer peeling force during printing and minimizing the final total support volume, a particle swarm optimization algorithm or a genetic algorithm is used for iterative adjustment. The optimization variables are the rotation angles of the model around the X, Y, and Z axes, the constraints are that the distance between the lowest point of the model and the printing substrate is ≥2mm, the maximum cantilever angle of the model is ≤30°, the number of iterations is set to 50-200, and the convergence condition is that the rate of change of the weighted fitness value of the two objectives is less than 1e-3, finally determining the optimal printing posture.

[0022] After the orientation is determined, equal-thickness layer slicing is performed. The slice thickness is set to 0.02mm-0.1mm (preferably 0.05mm) according to the printing accuracy requirements. The slice image of each layer is binarized, and the solidified contour line of each layer is extracted. At the same time, the area to be supported is identified based on the geometric features of the model. The area to be supported includes easily deformable areas such as cantilever structures (cantilever length ≥ 0.5mm and cantilever angle ≤ 45°), large planar structures, lower edges of cantilever holes, sharp corner structures, and thin-walled structures. The area to be supported is discretized into several nodes to be supported, and each node corresponds to a local position to be supported in the model.

[0023] S2. Construction of interlayer peel force prediction model and calculation of peel force field Based on the cross-sectional area of ​​each layer, the interlayer normal angle, and the adhesion characteristics of the photosensitive resin, a model for predicting interlayer peel force is constructed to obtain the peel force field distribution of each layer and local area of ​​the model.

[0024] First, a peel force calibration experiment was conducted on the photosensitive resin (acrylate / epoxy high-precision photosensitive resin) used in this printing: A sinking SLA photopolymerization printing platform of the same model was used, and different cured layer areas (5mm²) were set. 2 -5000mm 2 The model parameters were calibrated by measuring the thickness of the cured layer, the release film peeling speed (1 mm / s-10 mm / s), and the exposure energy gradient. The real-time peeling force during the separation process of the cured layer and the release film was collected by a high-precision tensile sensor. The peak function of the peeling force was obtained by fitting the data and the model parameters were calibrated.

[0025] In this embodiment, the peak peel force function expression of the peel force prediction model is: In the formula: This represents the peak peeling force in a localized area. The resin interfacial adhesion coefficient, obtained through calibration experiments, has a value ranging from 0.05 N / mm. 2 -0.3N / mm 2 ; This represents the section area of ​​the locally cured layer; This is the angle between the local normal of this layer and the printing peeling direction (positive Z-axis direction); This is the influence coefficient of the normal angle, with a calibration value of 0.2-0.8; This refers to the release film peeling speed; The speed influence index is calibrated to a value of 0.3-0.7; This is the structural stiffness influence coefficient. This refers to the elastic modulus of the cured resin. The moment of inertia of the local structure is used to characterize the effect of the local structural stiffness on the peeling force. The term serves as a structural stiffness correction term, with a relatively smaller numerical magnitude than the main term, and is used for fine-tuning compensation in local high-stiffness regions.

[0026] Based on the above-calibrated peel force prediction model, each layer after slicing is divided into grids with a size of 0.1mm-1mm. The peel force value of each grid cell is calculated to obtain the full interlayer peel force field distribution of the entire model from the first layer to the top layer. At the same time, the local peel force value corresponding to each node to be supported is output to provide load input for subsequent mechanical modeling.

[0027] S3, Construction of Mechanical Transmission Model Using the area to be supported as the load application point and the printed substrate as the constraint end, a mechanical transmission model is constructed based on the peeling force field.

[0028] In practice, the three-dimensional model is discretized into a finite element mesh model of tetrahedral elements, with the element size preferably between 0.2mm and 2mm, which can be adaptively adjusted according to the model's accuracy requirements. Each node in the area to be supported identified in S1 is used as a load application point, with the load magnitude being the local peeling force corresponding to that node calculated in S2, and the load direction being consistent with the printing peeling direction (positive Z-axis direction). The connection interface between the printing substrate and the model and the support structure is set as a fixed constraint end, constraining 6 degrees of freedom. At the same time, the elastic modulus, Poisson's ratio, fracture strength, and other mechanical property parameters of the photosensitive resin used are input to construct a complete linear elastic mechanical transmission model, which is used to simulate the transmission law of the peeling force load from the area to be supported to the printing substrate.

[0029] S4. Force-guided path optimization and transmission path network generation In the mechanical transmission model, the peeling force field is used as the weight field to perform top-down path optimization calculations, generating a force flow transmission path network from the area to be supported to the printed substrate.

[0030] In practical implementation, each discrete node to be supported in the region to be supported in S1 is taken as the starting point of path optimization, and the constraint surface of the printed substrate is taken as the ending point of path optimization. The peeling force field obtained in S2 is used as the weight field. The region with the larger peeling force has a higher weight in path optimization, prioritizing the efficient transmission of force flow. The A* algorithm is preferred for path optimization, with the FMM method used as an equivalent alternative. The following constraints are set during the optimization process: Path direction constraint: The overall path direction is opposite to the printing separation direction. The main direction extends towards the printing substrate along the negative Z-axis. The horizontal deviation angle of the path does not exceed 60° to avoid reverse paths and ensure the efficiency of vertical force flow transmission. Path curvature constraint: The path curvature changes continuously, and the radius of curvature is not less than 0.5mm to avoid stress concentration caused by sharp corner bends; Path merging constraint: When multiple paths intersect during the optimization process, they are automatically merged into the same path. The merging point adopts a smooth arc transition, and finally forms a tree-like topological force flow transmission path network with the substrate as the root and the area to be supported as the leaves. Interference avoidance constraint: The path must not interfere with the non-supported areas of the model body, ensuring that the support and the model only contact the area to be supported.

[0031] S5. Generation of hierarchical support skeleton network The force flow transmission path network is structured to generate a hierarchical support skeleton network, which includes main supports, secondary branches and end support units, and forms a continuous bifurcation structure at the path connection.

[0032] First, the force flow transmission path network generated by S4 is processed hierarchically. Based on the magnitude of the force flow transmitted through the path and the path level, the path network is divided into a three-level structure: Main support: The path that directly connects to the printing substrate and bears ≥10% of the total peel force, serving as the main channel for force transmission; Secondary branches: intermediate paths connecting the main support and the end support units, bearing the branch force flow; End support unit: The last level path that directly contacts the area to be supported in the model, and directly bears the peeling force load of the corresponding node to be supported.

[0033] The cross-sectional parameters of the hierarchical support framework network are optimized, including the diameter of the main support. Its branch diameter Optimization formula that satisfies Murray's law: , in, Preferred =2.7. This formula ensures optimal force transmission efficiency for the support frame while minimizing material consumption. For example, a main support branching into two secondary branches of equal diameter, each with a diameter of 1mm. When the value is 2.7, the calculated diameter of the main support is approximately 1.29 mm.

[0034] The arrangement rules for the hierarchical support skeleton network are as follows: the main supports are arranged along the main transmission direction of the peeling force (Z-axis direction) to reduce bending and ensure direct transmission of force flow; secondary branches extend towards the area to be supported, covering all nodes to be supported; the distribution density of the end support units is positively correlated with the magnitude of the local peeling force, specifically: in areas with peeling force ≥ 0.5N, the spacing of the end support units is set to 0.5mm-2mm; in areas with peeling force 0.1N-0.5N, the spacing is set to 2mm-5mm; in areas with peeling force < 0.1N, the spacing is set to 5mm-10mm, ensuring that the support stiffness is accurately matched with the peeling force load and avoiding over-support.

[0035] The continuous bifurcation structure at the path connection adopts a circular arc transition, and the radius of the transition arc is not less than 0.5 times the diameter of the main support to avoid stress concentration at the bifurcation.

[0036] The above parameters were determined based on printing accuracy, resin mechanical properties, and multiple sets of experimental verification.

[0037] After the hierarchical support skeleton network is generated, its structural optimization design is performed, including the following optimization methods, and the preferred optimization implementation method of the support structure: A controlled brittle fracture structure is provided at the contact point between the end support unit and the model. The controlled brittle fracture structure includes a fracture weak zone and an outer force transmission zone. The fracture weak zone is located at a distance of 0.3mm-1mm from the contact surface of the model. The cross-sectional size of the fracture weak zone is smaller than that of the force transmission zone, and its diameter is 0.2mm-0.6mm (preferably 0.4mm). The fracture weak zone is provided with circumferential and radial notches, and the depth of the notches is 10%-30% (preferably 20%) of the cross-sectional size.

[0038] The fracture weak zone achieves strength design through two-dimensional control: first, the structural cross-section is reduced, and mechanical weakening is achieved through the above-mentioned diameter and notch design; second, the exposure energy is locally reduced during the printing process, and the exposure energy of the fracture weak zone is set to 30%-60% of the exposure energy of the model body, so that its curing degree is lower than that of the model body and the supporting body, and finally the fracture strength of the fracture weak zone is lower than that of the surface strength of the model material.

[0039] The steps for removing the support after printing are as follows: After printing, first remove the printed part along with the substrate from the printing platform, remove most of the support body, and break the remaining end support remnants at the controlled brittle fracture structure. These remnants can be removed by gently prying them off with tweezers. For tiny remnants, immerse the printed part in anhydrous ethanol or a special cleaning solvent for the corresponding photosensitive resin for 5-30 minutes, and then treat it with ultrasonic treatment at 50W-200W and 40kHz for 1-10 minutes to achieve rapid and complete removal of the remnants without additional polishing, ensuring high precision and smoothness of the model surface.

[0040] A lattice buffer structure is set at the contact end of the end support unit and the model to reduce the impact on the model surface when the support is removed, and to adapt to the contact and bonding of complex curved surfaces. The lattice buffer structure is composed of periodic and non-periodic lattice units. The preferred lattice unit type is body-centered cubic (BCC), face-centered cubic (FCC) or topology-optimized lattice unit. The lattice unit size is 0.05mm to 0.5mm (preferably 0.2mm).

[0041] The relative density of the lattice buffer structure varies in a gradient from the contact center outwards. The relative density of the contact center region (the core area in direct contact with the model) is 50% to 90% (preferably 70%), ensuring the force transmission stiffness at the contact point. The relative density of the outer region is 10% to 60% (preferably 30%), forming a flexible buffer layer. Under the impact of the peeling force, it can produce slight deformation, avoiding stress concentration that could damage the model surface. At the same time, it reduces the contact area between the support and the model, making it easier to remove in post-processing.

[0042] The hierarchical support skeleton network is made porous by setting through channels inside the hierarchical support skeleton network to form a porous structure, which reduces support material consumption, reduces resin residue, and facilitates cleaning. The porosity of the porous structure is 60% to 90% (preferably 75%), the outer shell thickness of the support skeleton is 0.1 mm to 0.5 mm (preferably 0.3 mm), and the diameter of the internal through channels is 0.2 mm to 1.0 mm (preferably 0.6 mm). The channels are interconnected to form a mesh-like porous structure.

[0043] Porosity gradually changes along the support height: near the bottom of the support on the printing substrate, the porosity is set to 60%-70% to ensure the overall stability of the support; near the top of the support on the model, the porosity is set to 80%-90% to reduce the stiffness of the top of the support, avoid the support deformation from pulling on the model, and further reduce the amount of consumables used.

[0044] S6. Print Data Generation and Output The 3D printing data is generated and output based on the hierarchical support skeleton network for SLA photopolymerization. In specific implementation, the generated hierarchical support skeleton network is Boolean merged with the 3D model to be printed to generate a complete printed model with support. The complete model is then sliced ​​into layers with the same slicing parameters as in S1, generating exposure bitmap data for each layer. The final output is a printing format file (such as CLI, SLI, G code, etc.) that can be recognized by the SLA printer, which is then imported into the sink-type SLA photopolymerization 3D printer for printing.

[0045] This embodiment uses the method of the present invention to perform SLA photopolymerization printing support design on a high-precision complex thin-walled impeller model for aerospace applications. The model has a maximum outer diameter of 80mm, a height of 50mm, a blade wall thickness of 0.5mm, a minimum cantilever angle of 15°, and a printing accuracy requirement of ±0.02mm. A recessed SLA printer is used, with a slice layer thickness of 0.05mm. The photosensitive resin used is a high-precision acrylic resin with an elastic modulus of 2.8GPa and a tensile strength of 45MPa.

[0046] The specific implementation steps are as follows: Model preprocessing and attitude setting: Import the impeller STL model, repair geometric defects, and use the particle swarm optimization algorithm to iterate 100 times with the goal of minimizing the peak peeling force and the support volume. The optimal attitude is determined to be an angle of 12° between the impeller axis and the Z-axis. At this time, the maximum cantilever angle is increased to 28° and the peak peeling force is reduced by 32%. Layered slicing and extraction of areas to be supported: Using 0.05mm layer thickness equal thickness slices, a total of 1000 layers, the contour of each layer is extracted, and the blade cantilever area, leading edge sharp corner area, and hub lower edge area are identified as areas to be supported, which are discretized into 1268 nodes to be supported; Peel force field calculation: Calibration experiments were performed on the resin used to obtain... =0.12N / mm 2 , =0.5, =0.45, =1.2e-6, based on the calibration model, the full-layer peeling force field was calculated, and the maximum peeling force was 1.8N, located at the sharp corner of the blade leading edge; Mechanical transmission model construction: The node to be supported is taken as the load application point, the substrate is a fixed constraint, a finite element mechanical transmission model is constructed, the resin material parameters are input and the solution is completed; Path optimization and force flow network generation: Using the stripped force field as the weight field, the improved A* algorithm is adopted to optimize from top to bottom, starting from each node to be supported. The main direction of the path is constrained to be along the negative Z-axis and the radius of curvature is ≥0.5mm. Multiple paths are automatically merged to generate a tree-like force flow transmission path network. Hierarchical support framework generation: The path network is divided into three levels, with a total of 6 main supports arranged along the main Z-axis. Murray's law is used to design the cross-sectional parameters. =2.7, the maximum diameter of the main support is 2.2mm, the diameter of the secondary branch is 0.8-1.5mm, and the diameter of the end support unit is 0.3-0.6mm; the distribution density of the end support is positively correlated with the local peeling force, the support spacing in the area of ​​maximum peeling force is 1mm, and the spacing in the area of ​​minimum peeling force is 8mm. Support structure optimization: A controlled brittle fracture structure is set at the contact point between the end support and the model, with a fracture weak zone diameter of 0.3 mm, a circumferential notch depth of 0.06 mm, and an exposure energy of 50% of the model; the main support and secondary branches are treated with porosity, with an average porosity of 75%, an outer shell thickness of 0.3 mm, an internal channel diameter of 0.5 mm, and porosity gradually changing from 70% at the bottom to 85% at the top along the height. Printing and post-processing: The support and model are merged, sliced ​​to generate print files, and imported into an SLA printer to complete printing; after printing, the support breaks first at the controlled brittle fracture structure, and is completely removed after solvent soaking and 5 minutes of ultrasonic treatment. The model surface is undamaged and without warping deformation. The dimensional accuracy meets the requirement of ±0.02mm. The support volume is reduced by 48% compared with the traditional empirical support, and the printing success rate is 100%.

[0047] The above description is only a preferred embodiment of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0048] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A high-precision SLA photopolymerization 3D printing support structure design method, characterized in that, Includes the following steps: S1. Obtain the 3D model to be printed, set the pose of the model and slice it into layers, and extract the contours of each layer and the area to be supported. S2. Based on the cross-sectional area of ​​each layer, the interlayer normal angle and the adhesion characteristics of the photosensitive resin, a prediction model for interlayer peel force is constructed to obtain the peel force field distribution of each layer and local area of ​​the model. S3. Using the area to be supported as the load application point and the printed substrate as the constraint end, construct a mechanical transmission model based on the peeling force field; S4. In the mechanical transmission model, the peeling force field is used as the weight field, and a top-down path optimization calculation is performed to generate a force flow transmission path network from the area to be supported to the printed substrate. S5. The force flow transmission path network is structured to generate a hierarchical support skeleton network. The hierarchical support skeleton network includes main supports, secondary branches and end support units, and the path connection forms a continuous branching structure. S6. Generate and output 3D printing data based on the hierarchical support skeleton network for SLA photopolymerization molding.

2. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: The peel force prediction model in S2 includes at least resin interface adhesion force, delamination area, peel speed and local structural stiffness parameters, and the peak peel force function is obtained through experimental calibration.

3. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: The path optimization calculation in S4 satisfies the constraints that the overall path direction is opposite to the printing separation direction and the path curvature changes continuously. When the path network is generated, the area to be supported is discretized into multiple load points. Path search is performed with each load point as the starting point. When multiple paths intersect, they are merged to form a tree-like topology.

4. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: The cross-sectional parameters of the hierarchical support skeleton network in S5 satisfy the following: main support diameter Its branch diameter satisfy ,in .

5. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: In the hierarchical support skeleton network, the main supports are arranged along the main transmission direction of the peeling force, the secondary branches extend toward the area to be supported, and the distribution density of the end support units is positively correlated with the magnitude of the local peeling force.

6. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: A controlled brittle fracture structure is provided at the contact point between the end support unit and the model. The controlled brittle fracture structure includes a weak fracture zone and an outer force transmission zone. The cross-sectional size of the weak fracture zone is smaller than that of the force transmission zone, with a diameter of 0.2 mm to 0.6 mm and circumferential and radial notches. The depth of the notches is 10% to 30% of the cross-sectional size. The weak fracture zone is formed by locally reducing the exposure energy and reducing the cross-sectional area of ​​the structure, so that its fracture strength is lower than the surface strength of the model material.

7. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: The end support unit is provided with a lattice buffer structure at the contact end with the model. The lattice buffer structure is composed of periodic and non-periodic lattice units with a size of 0.05 mm to 0.5 mm and a relative density that varies in gradient from the contact center outward, with 50% to 90% at the contact center and 10% to 60% on the outer side.

8. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: The hierarchical support skeleton network is made porous by setting through channels inside the hierarchical support skeleton network to form a porous structure. The porosity of the porous structure is 60% to 90%, the outer shell thickness is 0.1 mm to 0.5 mm, the internal channel diameter is 0.2 mm to 1.0 mm, and the porosity gradually changes along the support height direction.

9. The high-precision SLA photopolymerization 3D printing support structure design method according to claim 1, characterized in that: Before S1, the model attitude is optimized by iteratively adjusting the parameters to minimize the peak peeling force and the support volume.

10. A high-precision SLA photopolymerization 3D printing support structure design method according to claim 6, characterized in that: The method also includes a post-printing support removal step, wherein the support preferentially fractures at the controlled brittle fracture structure and is rapidly removed by solvent cleaning and ultrasonic treatment.

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