CN-116070370-B - Thin-wall curved surface porous part design method oriented to laser selective melting technology

CN116070370BCN 116070370 BCN116070370 BCN 116070370BCN-116070370-B

Abstract

The invention relates to a thin-wall curved surface porous part design method for a laser selective melting technology, which comprises the specific steps of S1 preparing a thin-wall curved surface model, S2 constructing a filling unit body, S3 carrying out curvature analysis on the thin-wall curved surface model and optimizing the filling direction, wherein the curvature analysis on the thin-wall curved surface structure in the S1 is carried out, the filling direction is optimized and determined by combining a short side filling vector n h of the unit body, S4 constructing the thin-wall curved surface porous model, constructing a space lattice structure taking the unit body as a porous unit, correcting the geometric line-surface relation of a lattice cell, carrying out porous construction on the thin-wall curved surface model through Boolean intersection operation based on a filling scheme, and S5 manufacturing an additive. The design method of the thin-wall curved surface porous part for additive manufacturing provided by the invention can solve the problem of difficult processing of a thin-wall curved surface porous structure of selective laser melting.

Inventors

HAN CHANGJUN
WANG YUNHUI
DONG ZHI
Hu Gaoling
WANG DI
SONG CHANGHUI
YANG YONGQIANG

Assignees

华南理工大学

Dates

Publication Date: 20260505
Application Date: 20230119

Claims (10)

1. A design method of a thin-wall curved surface porous part facing a laser selective melting technology is characterized by comprising the following steps: S1, preparing a thin-wall curved surface model, namely modeling the thin-wall curved surface model or obtaining a solid model by using three-dimensional scanning; S2, constructing a filling unit cell, namely designing a porous filling unit cell according to the performance requirement of the thin-wall curved surface structure, combining a manufacturing process parameter library, completing the parameter model construction of the filling unit cell, analyzing the boundary rectangle of the unit cell, and determining the short-side filling vector n h of the unit cell; S3, performing curvature analysis on the thin-wall curved surface model and optimizing the filling direction, namely performing curvature analysis on the thin-wall section of the thin-wall curved surface structure in the step S1, and optimizing and determining the filling direction by combining the short-side filling vector n h of the unit cell; S4, constructing a thin-wall curved surface porous model, namely constructing a space lattice structure taking a unit cell body as a porous unit, correcting the geometric line-surface relation of a unit cell lattice, and performing porous construction on the thin-wall curved surface model through Boolean intersection operation based on a filling scheme; S5, additive manufacturing, namely using a laser selective melting technology, placing the thin-wall curved surface porous model based on the principle of small Z-axis height after the thin-wall curved surface porous model is introduced, setting processing laser power, light spot diameter, slice thickness and conical supporting parameters by taking the supporting type of the thin-wall curved surface porous model as a cone, and finishing additive manufacturing.
2. The method for designing a thin-wall curved surface porous part facing a laser selective melting technology according to claim 1, wherein in the step S1, the thickness of the thin-wall curved surface model is 0.4 mm-1.0 mm.
3. The method for designing a thin-walled curved porous part for a laser selective melting technology according to claim 1, wherein in step S1, the thickness of each thin-walled curved surface of the thin-walled curved surface model is kept uniform.
4. The method for designing a thin-walled curved porous part for a laser selective melting technology according to claim 1, wherein in step S1, the thin-walled curved surface model is expressed using a triangular patch grid of STL file format.
5. The method for designing a thin-walled curved porous part according to claim 1, wherein in step S2, the boundary rectangles of the unit cell are analyzed, the short-side filling vector n h of the unit cell is determined, specifically, the boundary rectangles with the shortest feature size are determined by performing size analysis on each boundary rectangle of the unit cell, and the direction vector of the shortest side of the boundary rectangle is the short-side filling vector n h .
6. The method for designing a thin-walled curved porous part for a laser selective melting technology according to claim 1, wherein in step S3, the specific steps of curvature analysis and optimization of filling direction are as follows: a. Analyzing a thin-wall section of the thin-wall curved surface structure, intercepting points on the curved edge at equal intervals according to unit cell filling intervals, and representing the curvature of the curved edge section by using normal vectors n t of the points; b. For a single unit cell, the direction vector n h of the shortest side of the boundary rectangle is overlapped with the normal vector n t of the curved edge, and at the moment, the included angle between n h and n t is the optimal angle alpha=0°, so that the optimal filling effect is achieved; c. For a plurality of unit cells, the optimized angle alpha exists between the direction vector n h and the curved edge normal vector n t of each unit cell, and the average optimized angle of the n unit cells is recorded as D. Comparing the filling schemes, selecting an average optimization angle Minimum filling scheme.
7. The method for designing a thin-wall curved surface porous part for laser selective melting technology according to claim 1, wherein in step S4, the constructing a curved surface porous model includes geometric line surface correction of a lattice, unit cell array, boolean operation, and specifically includes the following steps: a', measuring a boundary rectangle of the thin-wall curved surface structure based on a filling scheme, and determining the filling quantity of unit cells according to the characteristic size of the unit cells; b', detecting triangular patches of the unit cell body, including gaps, interference shells, holes, broken edges, overlapping and crossed triangular patches, and repairing overlapping line surfaces and crossed shells generated by the unit cell body under parameterization modeling; c', carrying out XY plane array by taking a unit cell as a unit, repeating the geometric line surface correction process, detecting and repairing the triangular surface patches of the plane lattice, then carrying out space array in the Z-axis direction, and detecting and repairing the geometric line surface relation of the lattice again; d', importing a thin-wall curved surface STL model, and carrying out Boolean intersection operation on the basis of a filling scheme and a space lattice structure; e', detecting and repairing the thin-wall curved surface porous model.
8. The method for designing a thin-wall curved surface porous part facing a laser selective melting technology according to claim 1, wherein in step S5, the power range of the processing laser is 60 w-80 w; The diameter range of the light spot is 0.03-0.07 mm; the thickness of the slice is 0.02 mm-0.06 mm.
9. The method for designing a thin-walled curved porous part for a laser selective melting technology according to claim 1, wherein in step S5, model overlapping in the Z-axis direction is avoided or reduced based on a principle of placement of a small Z-axis height, and when there is model curling overlapping, the support of the upper overlapping portion is required to be deflected by 1 ° to 3 ° and supported at the node of the lower overlapping portion to avoid passing through the hole.
10. The method for designing a thin-walled curved porous part for a laser selective melting technology according to claim 1, further comprising the steps of, after step S5: S6, supporting and disassembling are carried out after the additive manufacturing is completed, wherein the supports with two ends connected to the thin-wall curved surface structure are shortened from the middle so that the supports are conveniently disassembled from the thin-wall curved surface structure.

Description

Thin-wall curved surface porous part design method oriented to laser selective melting technology Technical Field The invention relates to the technical field of additive manufacturing, in particular to a thin-wall curved surface porous part design method facing to a laser selective melting technology. Background The additive manufacturing technology is an incremental manufacturing technology for completing part manufacturing through layer-by-layer stacking of materials, has higher processing efficiency than the traditional processing technology in the aspect of forming complex curved surface structures, and is mainly applied to the fields of aerospace, biomedical treatment, automobile part manufacturing and the like at present. The special processing characteristic of layer-by-layer stacking ensures that the additive technology has unique advantages in the precision manufacturing of porous structures, and can form micron-sized pore characteristic parts. The expression method of the porous structure is mainly divided into three types, namely discrete voxel expression, parametric expression and implicit function expression. The discrete voxel expression forms a porous structure through density distribution on a three-dimensional space middle-scale integral pixel grid, the porous structure of a geometric model is expressed through discrete point values and is mainly applied to the field of topological optimization, an implicit function method can define any point value of the porous model, an existing multiple porous unit is expressed by a mathematical function, the porous structure with multiple composite configurations is constructed by utilizing a function combination mode, and the parameterization expression method is a mainstream CAD modeling method and is provided with a plurality of integrated parameterized geometric prototypes (such as spheres, columns, cuboids, beam units and the like), and the porous unit can be constructed and represented based on the basic units. At present, parameterized porous model construction has the defect that parameterized expression mode enables porous units to contain more redundant geometric data after combination, and only a simple model can be subjected to porous Boolean operation. The thin-wall curved surface type porous structure is widely applied in the fields of oral cavity guided bone regeneration and the like, generally has a complex curved surface and a thin wall below 1mm, a parameterized porous model is difficult to construct through Boolean operation, and the thin wall characteristics enable the unit cell integrity of the porous thin-wall curved surface type structure to be low and the structural strength to be low, so that the porous thin-wall curved surface type structure is difficult to process. Disclosure of Invention Based on the design method, the invention provides a thin-wall curved porous part design method for additive manufacturing, and solves the problem that a laser selective melting thin-wall curved porous structure is difficult to process. In order to achieve the above purpose, the present invention provides the following technical solutions: A design method of a thin-wall curved surface porous part facing a laser selective melting technology comprises the following steps: S1, preparing a thin-wall curved surface model, namely modeling the thin-wall curved surface model or obtaining a solid model by using three-dimensional scanning; S2, constructing a filling unit cell, namely designing a porous filling unit cell according to the performance requirement of the thin-wall curved surface structure, combining a manufacturing process parameter library, completing the parameter model construction of the filling unit cell, analyzing the boundary rectangle of the unit cell, and determining the short-side filling vector n h of the unit cell; S3, performing curvature analysis on the thin-wall curved surface model and optimizing the filling direction, namely performing curvature analysis on the thin-wall section of the thin-wall curved surface structure in the step S1, and optimizing and determining the filling direction by combining the short-side filling vector n h of the unit cell; S4, constructing a thin-wall curved surface porous model, namely constructing a space lattice structure taking a unit cell body as a porous unit, correcting the geometric line-surface relation of a unit cell lattice, and performing porous construction on the thin-wall curved surface model through Boolean intersection operation based on a filling scheme; S5, additive manufacturing, namely using a laser selective melting technology, placing the thin-wall curved surface porous model based on the principle of small Z-axis height after the thin-wall curved surface porous model is introduced, setting processing laser power, light spot diameter, slice thickness and conical supporting parameters by taking the supporting type of the thin-wall curved surface porous model as a cone, a