A powder feeding path planning method based on powder bed multi-material additive manufacturing

Abstract

The application discloses a powder feeding path planning method based on powder bed multi-material additive manufacturing. Firstly, the target structure is subjected to slicing processing, and the slice contour of the second structure is separated. Then, the regions with a width less than a critical value in the slice contour are identified and extracted to generate and fill single road lines. Then, the Z-shaped filling strategy is used to fill the remaining unfilled regions. The method further includes an overall offset processing step to compensate for errors that may be generated during the scraper powder laying process. Finally, the path planning process is repeated on each slice layer through cyclic iteration until the powder feeding path planning of the entire target structure is completed. The method can fully cover the slice area of the second material model, ensure full coverage, reduce material mixing pollution, improve powder feeding efficiency, save time, and has important practical value and wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of additive manufacturing, and relates to a powder feeding path planning method in an additive manufacturing process, in particular to a powder feeding path planning method in a multi-material additive manufacturing process based on a powder bed, which can fully cover the slicing area of a second material model, ensure full coverage, minimize the mixing and pollution of the second material and the base material, improve powder feeding efficiency, and save time. BACKGROUND

[0002] Additive manufacturing (AM) is a technology that uses digital models and layer-by-layer stacking to manufacture complex-shaped parts or products. Additive manufacturing technology has the advantages of high efficiency, energy saving, environmental protection, flexibility, etc., and has been widely applied in the fields of aerospace, automobile, medical treatment, energy, etc. However, the current additive manufacturing technology is mainly single-material manufacturing, which cannot meet the manufacturing requirements of structural parts with composite functions in specific occasions, for example, in the field of aerospace, it is necessary to manufacture composite material structural parts with high strength, high thermal conductivity, corrosion resistance and other multiple properties. With the continuous development and innovation of additive manufacturing technology, multi-metal additive manufacturing (MMAM) as a new direction in this field gradually shows great application potential. MMAM refers to the use of two or more different metal materials in the same additive manufacturing process to manufacture structural parts with composite functions or gradient properties, which can realize precise control and combination of different materials and provide new possibilities for the manufacturing of composite function structural parts. For example, through MMAM technology, NASA in the United States manufactured a bimetallic rocket engine thrust chamber using GRCOP-84 copper alloy and chromium-nickel-iron alloy, which has high thermal conductivity of copper alloy and high strength of chromium-nickel-iron alloy.

[0003] Existing multi-metal additive manufacturing technologies can be divided into two categories: powder bed multi-metal additive manufacturing (PBMAM) and direct energy deposition multi-metal additive manufacturing (DEDMAM). Currently, PPMAM technology is mainly used in multi-metal powder bed additive manufacturing processes. It achieves layer-by-layer deposition of different materials through multiple powder layering and scanning within the layer. Lasers or electron beams are used as energy sources on the powder bed to melt different metal powders layer by layer to manufacture multi-metal structural components. Specifically, PPMAM technology mainly includes the following steps: First, the first type of material powder required for the substrate structure is laid down using a scraper. Then, the substrate is sintered and solidified using a laser or electron beam. Next, a powder feeding device is used to lay down the second type of powder for the second structure. The second type of powder is then leveled using a scraper, and finally, the second type of powder is sintered again using a laser or electron beam to achieve the connection and fixation of multiple materials.

[0004] However, multi-metal additive manufacturing technology based on powder bed sintering faces many challenges and problems, one of which is how to effectively plan the powder feeding path of the powder feeding device. Path planning is a key step in the powder feeding process, directly affecting the coverage rate of the second material and the sintering quality. The purpose of powder feeding path planning is to ensure that during the second powder spreading process, the sliced ​​area of ​​the second material is completely covered in the subsequent powder scraping process to ensure the integrity and functionality of the multi-material structure, while ensuring that the second material does not contaminate the first powder to guarantee the purity and performance of different materials. However, since existing powder feeding devices mainly use screw extrusion to transport powder, the current powder feeding path planning methods suitable for single-material manufacturing are not suitable for multi-metal powder bed additive manufacturing.

[0005] In summary, developing a powder feeding path planning algorithm specifically for powder bed-based multi-metal additive manufacturing technology to ensure full coverage of the sliced ​​area of ​​the second material model, minimize mixing and contamination between the second material and the matrix material, improve powder feeding efficiency, and save time are urgent technical problems to be solved. Summary of the Invention

[0006] (I) Purpose of the Invention

[0007] In view of the technical problem that the current path planning technology is not applicable to the multi-metal powder bed additive manufacturing technology due to the fact that the existing powder feeding device mainly uses screw extrusion powder, the application aims to provide a powder feeding path planning method for a multi-material additive manufacturing process based on a powder bed, which can fully cover the slicing area of a second material model, ensure full coverage, minimize the mixing and pollution of the second material and the base material, improve the powder feeding efficiency, and save time.

[0008] (II) Technical solutions

[0009] To achieve the above object, the application adopts the following technical solutions:

[0010] A powder feeding path planning method for multi-material additive manufacturing based on a powder bed, characterized in that the powder feeding path planning method comprises at least the following steps when implemented:

[0011] SS1. Based on the three-dimensional model data of a target structure, using slicing technology and based on a preset slicing thickness h, the target structure is sliced at a preset slicing height z to generate a two-dimensional slicing contour reflecting the cross-sectional structure information of the target structure at the height z, and based on the two-dimensional slicing contour, the two-dimensional slicing contour C(z) of the second structure in the target structure is identified and separated, thereby providing basic geometric information for subsequent powder feeding path planning, wherein the target structure is a multi-metal structure composed of at least two different metal materials, and the second structure is a structure formed by a metal material other than the base material in the target structure other than the base structure;

[0012] SS2. The two-dimensional slicing contour C(z) of the second structure is preprocessed, and a geometric analysis algorithm is applied to identify and extract the area with a width less than a critical value width w in the two-dimensional slicing contour C(z). In the extracted area, according to the geometric shape and size of the area, a single path line L(z) is generated and filled, thereby providing accurate path guidance for subsequent powder feeding operations, wherein the critical value width w is the powder spreading width after the movement of the powder feeding device, and the single path line L(z) is a set of center points of the extracted area, the length of which is equal to the maximum length of the area and the maximum distance parallel to the powder spreading direction, so as to ensure uniform powder coverage during powder feeding;

[0013] SS3. Applying a geometric analysis algorithm to subtract the single-path line L(z) from the two-dimensional slice contour C(z) of the second structure to obtain a remaining unfilled area R(z), and performing path filling on the remaining unfilled area R(z), using a preset zigzag filling strategy during the filling process, the filling vector direction being perpendicular to the doctor blade powder laying direction to ensure uniform and effective powder coverage during powder feeding, the filling vector width being equal to the critical value width w after single-path powder scattering to maintain the uniformity and efficiency of the filling, and obtaining a set of filling vectors through zigzag filling and forming a filling vector set V(z);

[0014] SS4. Merging the single-path line L(z) obtained in step SS2 and the filling vector set V(z) obtained in step SS3 into a powder feeding path set P(z), and performing overall offset processing on the powder feeding path set P(z), wherein the overall offset size d is equal to the center offset amount after the single-path powder scattering is laid flat by the doctor blade to compensate for errors that may be caused by physical dynamics effects during the doctor blade powder laying process, and the overall offset direction is the opposite direction of the doctor blade powder laying direction to ensure that there is no gap or overlap during the subsequent doctor blade powder removal process, and to ensure uniform and efficient powder coverage during actual powder feeding;

[0015] SS5. Moving the slice height z upward by a slice thickness h, and repeating steps SS2-SS4 on the next slice layer until the slice height z reaches the maximum height of the target structure, and ending the powder feeding path planning process.

[0016] Preferably, in the above step SS1, the slice technique uses a contour generation method based on three-dimensional reconstruction technology, generates high-precision and high-quality two-dimensional slice contours based on three-dimensional model data of the target structure, and effectively processes complex contour shapes and topological structures, thereby providing accurate basic information for subsequent powder feeding path planning.

[0017] Preferably, in the above step SS1, the slice processing further includes optimization processing of the obtained two-dimensional slice contour C(z) to eliminate possible geometric defects and non-ideal slice features, and to ensure that the quality of the two-dimensional slice contour C(z) meets the needs of powder feeding path planning.

[0018] Preferably, in the above step SS2, the geometric analysis algorithm uses an area recognition and extraction method based on the ant colony algorithm, uses the global search ability and local adjustment ability of the ant colony algorithm based on the pixel point distribution and adjacent relationship in the two-dimensional slice contour C(z), quickly recognizes and extracts the area with a width less than the critical value w, and generates the corresponding single-path line L(z).

[0019] Preferably, in the step SS2, the pre-processing further comprises optimizing and correcting the generated single path line L(z) to eliminate possible path intersections and overlaps, and to ensure that the quality and accuracy of the single path line L(z) meet the requirements of the powder feeding path planning.

[0020] Preferably, in the step SS2, the generation and filling of the single path line L(z) are realized by a path generation algorithm based on Bezier curve or B-spline curve, to ensure the smoothness and continuity of the filled path, and to improve the efficiency and accuracy of the powder feeding operation.

[0021] Preferably, in the step SS3, the zigzag filling strategy adopts an optimization method based on genetic algorithm, and according to the geometric characteristics and constraint conditions in the remaining unfilled area R(z), the adaptive evaluation, selection, crossover and mutation operations of the genetic algorithm are used to find the optimal zigzag filling scheme and generate the corresponding filling vector set V(z), so as to realize the optimization of the filled path and ensure the filling efficiency and quality.

[0022] Preferably, in the step SS3, the generation of the filling vector is realized by applying a path generation technology based on vector field, to ensure the continuity and uniformity of the filled path.

[0023] Preferably, in the step SS4, the overall offset processing adopts a simulation method based on finite element analysis technology, and according to the geometric parameters and physical parameters in the powder feeding path set P(z), the finite element analysis technology is used to simulate and calculate various influencing factors in the powder feeding process, and the optimal overall offset d is obtained, to improve the accuracy and efficiency of the powder feeding path planning.

[0024] Preferably, in the step SS5, before moving one slice thickness h in the slice height z direction, the powder feeding path set P(z) of the current layer is evaluated, a multi-objective optimization technology is applied to evaluate the powder feeding path set P(z), and according to the evaluation result, the powder feeding path set P(z) is adjusted and optimized to at least balance multiple objective functions including the length, time, energy consumption and quality of the powder feeding path.

[0025] (Three) Technical effects

[0026] Compared with the prior art, the powder feeding path planning method based on powder bed multi-material additive manufacturing of the present application has the following beneficial and significant technical effects:

[0027] (1) The present application addresses the problem that existing powder feeding devices mainly use screw extrusion, which leads to the current path planning technology not being suitable for multi-metal powder bed additive manufacturing technology. A novel powder feeding path planning method is provided. This method significantly improves the applicability of path planning technology for multi-material additive manufacturing processes based on powder beds.

[0028] (2) The present application can fully cover the slice area of the second structure through precise powder feeding path planning, ensuring full coverage while minimizing the mixing and contamination of the second material with the base material, which helps to ensure the quality and performance of the final product of the target structure.

[0029] (3) The present application can effectively generate and fill single road lines through slicing technology and geometric analysis algorithms, and improve powder feeding efficiency and save time through the application of zigzag filling strategy. These technical improvements help to accelerate the additive manufacturing process, reduce production time and cost.

[0030] (4) The present application can compensate for errors that may occur due to physical dynamics effects during the scraper powder laying process through overall offset processing, ensuring that there will be no gaps or overlaps in the subsequent powder scraping process, ensuring uniform and efficient powder coverage, and improving the uniformity and quality of the powder bed. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The flowchart of the powder feeding path planning method based on powder bed multi-material additive manufacturing of the present application is shown.

[0032] Figure 2 The three-dimensional structure diagram of the second structure is shown.

[0033] Figure 3 The two-dimensional slice contour diagram of the second structure is shown.

[0034] Figure 4 The single road line diagram is shown.

[0035] Figure 5 The filling trajectory diagram is shown.

[0036] Figure 6 The zigzag filling strategy diagram is shown.

[0037] Figure 7 The overall offset processing diagram is shown. DETAILED DESCRIPTION

[0038] For better understanding of the present application, the following further illustrates the content of the present application in conjunction with the embodiments. In the drawings, the same or similar notations represent the same or similar elements or elements with the same or similar functions throughout. The described embodiments are part of the embodiments of the present application, but not all the embodiments. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, but cannot be understood as a limitation of the present application.

[0039] Figure 1 A flow chart of a powder path planning method for powder bed multi-material additive manufacturing of the present application is shown, which comprises at least the following steps when implemented:

[0040] SS1. Based on the three-dimensional model data of the target structure, using the slicing technique and based on the preset slicing thickness h, the target structure is sliced at the preset slicing height z to generate a two-dimensional slice contour reflecting the cross-sectional structure information of the target structure at the height z, and based on the two-dimensional slice contour, the second structure in the target structure is identified and separated as Figure 3 The two-dimensional slice contour C(z) is shown, thereby providing basic geometric information for subsequent powder path planning, wherein the target structure is a multi-metal structure composed of at least two different metal materials, and the second structure (as shown in Figure 2 ) is a structure formed by a metal material other than the base material in the region other than the base structure of the target structure.

[0041] In preferred examples of the present application, the above-mentioned slicing technique adopts a contour generation method based on three-dimensional reconstruction technology, based on the three-dimensional model data of the target structure, using three-dimensional reconstruction algorithm and surface fitting technology, to generate high-precision and high-quality two-dimensional slice contour, and effectively process complex contour shape and topological structure, thereby providing accurate basic information for subsequent powder path planning.

[0042] In addition, the slicing process can also include optimization processing of the obtained two-dimensional slice contour C(z) to eliminate possible geometric defects and non-ideal slicing features, to ensure that the quality of the two-dimensional slice contour C(z) meets the needs of the powder path planning.

[0043] SS2. The two-dimensional slice contour C(z) of the second structure is pre-processed, and a geometric analysis algorithm is applied to identify and extract the region with a width less than a critical value width w in the two-dimensional slice contour C(z). In the extracted region, according to the geometric shape and size of the region, a single road line L(z) as shown in Figure 4 is generated and filled, and based on the single road line L(z), a single road as shown in Figure 5The filling trajectory is shown, thereby providing accurate path guidance for subsequent powder feeding operations, wherein the critical value width w is the powder spreading width after the powder feeding device moves a single pass, and the single pass line L(z) is a set of center points of the extracted region, the length of which is equal to the maximum length of the region and parallel to the maximum distance of the scraper powder laying direction, to ensure uniform powder coverage during powder feeding.

[0044] In the preferred example of the present application, in the above step SS2, the geometric analysis algorithm adopts an area recognition and extraction method based on the ant colony algorithm, based on the pixel point distribution and adjacent relationship in the two-dimensional slice contour C(z), using the global search ability and local adjustment ability of the ant colony algorithm, the area with a width less than the critical value w is quickly recognized and extracted, and the corresponding single pass line L(z) is generated.

[0045] In addition, the pre-processing also includes optimizing and correcting the generated single pass line L(z) to eliminate possible path intersections and overlaps, to ensure that the quality and accuracy of the single pass line L(z) meet the needs of powder feeding path planning. The generation and filling of the single pass line L(z) can be realized by a path generation algorithm based on Bezier curve or B-spline curve, to ensure the smoothness and continuity of the filling path, and to improve the efficiency and accuracy of powder feeding operation.

[0046] SS3. Apply a geometric analysis algorithm to subtract the single pass line L(z) from the two-dimensional slice contour C(z) of the second structure to obtain the remaining unfilled area R(z), and perform path filling on the remaining unfilled area R(z). During the filling process, a preset zigzag filling strategy (such as Figure 6 The filling vector direction is perpendicular to the scraper powder laying direction to ensure uniform and effective powder coverage during powder feeding, and the filling vector width is equal to the critical value width w after a single pass of powder spreading to maintain the uniformity and efficiency of filling. A set of filling vectors is obtained by zigzag filling and formed into a filling vector set V(z).

[0047] In the preferred example of the present application, in the above step SS3, the zigzag filling strategy adopts an optimization method based on genetic algorithm, according to the geometric features and constraints in the remaining unfilled area R(z), using the adaptive evaluation, selection, crossover and mutation operations of genetic algorithm, to find the optimal zigzag filling scheme and generate the corresponding filling vector set V(z), to realize the optimization of the filling path and ensure the filling efficiency and quality. In addition, the generation of the filling vector is realized by applying a vector field based path generation technique to ensure the continuity and uniformity of the filling path.

[0048] SS4. Merge the single-path L(z) obtained in step SS2 and the filling vector set V(z) obtained in step SS3 into a powder feeding path set P(z), and perform an overall offsetting process (as shown in Figure 7 the size d of the overall offsetting is equal to the center offsetting amount after the powder spreading single-path is flattened by the squeegee, so as to compensate for the error possibly caused by the physical dynamics effect in the squeegee powder spreading process, and the direction of the overall offsetting is opposite to the squeegee powder spreading direction, so as to ensure that there is no gap or overlap in the subsequent squeegee powder spreading process.

[0049] In the preferred example of the present application, in step SS4, the overall offsetting process adopts a simulation method based on finite element analysis technology, and according to the geometric parameters and physical parameters in the powder feeding path set P(z), the finite element analysis technology is used to simulate and calculate each influencing factor in the powder feeding process, and the best or suboptimal overall offsetting amount d is obtained, so as to improve the accuracy and efficiency of the powder feeding path planning.

[0050] SS5. Move the slice height z upward by a slice thickness h, and repeat steps SS2-SS4 on the next slice layer, until the maximum height of the target structure is reached, and the powder feeding path planning process is ended.

[0051] In the preferred example of the present application, before moving the slice height z upward by a slice thickness h, the powder feeding path set P(z) of the current layer is evaluated, a multi-objective optimization technology is applied to evaluate the powder feeding path set P(z), and the powder feeding path set P(z) is adjusted and optimized according to the evaluation result, so as to at least balance multiple objective functions including the length, time, energy consumption and quality of the powder feeding path.

[0052] The above embodiments completely and effectively achieve the purpose of the present application. Those skilled in the art can understand that the present application includes but is not limited to the contents described in the drawings and the above specific embodiments. Although the present application has been described with respect to the presently preferred and most advantageous embodiments, it should be understood that the present application is not limited to the disclosed embodiments, and any modification that does not deviate from the functional and structural principles of the present application will be included in the scope of the claims.

Claims

1. A method of powder path planning for multi-material additive manufacturing based on powder bed, characterized in that, The powder feeding path planning method comprises the following steps when implemented: SS1. Based on the three-dimensional model data of the target structure, using the slicing technique and based on the preset slice thickness h, slice the target structure at the preset slice height z to generate a two-dimensional slice contour reflecting the cross-sectional structure information of the target structure at the height z, and identify and separate the two-dimensional slice contour C(z) of the second structure in the target structure based on the two-dimensional slice contour, wherein the target structure is a multi-metal structure composed of at least two different metal materials, and the second structure is a structure formed by a metal material other than the base material in the target structure except the base structure; SS2. Preprocess the two-dimensional slice contour C(z) of the second structure, and apply a geometric analysis algorithm to identify and extract the area with a width less than a critical value width w in the two-dimensional slice contour C(z). In the extracted area, according to the geometric shape and size of the area, a single path line L(z) is generated and filled, wherein the critical value width w is the powder scattering width after the single path of the powder feeding device moves, and the single path line L(z) is a set of center points of the extracted area, the length of which is equal to the maximum length of the area and the maximum distance parallel to the scraper powder laying direction; SS3. Apply a geometric analysis algorithm to subtract the single path line L(z) from the two-dimensional slice contour C(z) to obtain a remaining unfilled area R(z), and perform path filling on the remaining unfilled area R(z). In the filling process, a preset zigzag filling strategy is used, the filling vector direction is perpendicular to the scraper powder laying direction, and the filling vector width is equal to the critical value width w after the single path of the powder scattering is laid to maintain the uniformity and efficiency of the filling. A set of filling vectors is obtained through zigzag filling and formed into a filling vector set V(z); SS4. Merge the single path line L(z) calculated in step SS2 and the filling vector set V(z) calculated in step SS3 into a powder feeding path set P(z), and perform overall offset processing on the powder feeding path set P(z), wherein the size d of the overall offset is equal to the center offset amount after the single path of the powder scattering is laid by the scraper to compensate for the error that may be caused by the physical dynamics effect in the process of the scraper powder laying, and the direction of the overall offset is the opposite direction of the scraper powder laying direction; SS5. Move the slice height z upward by one slice thickness h, and repeat steps SS2-SS4 on the next slice layer until the slice height z reaches the maximum height of the target structure.

2. The powder bed-based multi-material additive manufacturing powder delivery path planning method of claim 1, wherein, In the above step SS1, the slicing technique adopts a contour generation method based on three-dimensional reconstruction technology. Based on the three-dimensional model data of the target structure, a high-precision and high-quality two-dimensional slice contour is generated by using three-dimensional reconstruction algorithm and surface fitting technology, and complex contour shapes and topological structures are effectively processed.

3. The powder bed-based multi-material additive manufacturing powder delivery path planning method of claim 1, wherein, In the above step SS1, the slicing process further comprises optimization processing of the obtained two-dimensional slice contour C(z) to eliminate possible geometric defects and non-ideal slice characteristics.

4. The powder bed-based multi-material additive manufacturing powder delivery path planning method of claim 1, wherein, In the step SS2, the geometric analysis algorithm adopts an area recognition and extraction method based on ant colony algorithm, based on the pixel point distribution and adjacent relationship in the two-dimensional slice contour C(z), using the global search ability and local adjustment ability of ant colony algorithm, quickly recognizing and extracting the area with a width less than the critical value w, and generating the corresponding single road line L(z).

5. The powder path planning method for multi-material additive manufacturing based on powder bed according to claim 1, wherein, In the step SS2, the pre-processing further includes optimizing and correcting the generated single road line L(z) to eliminate possible path intersection and overlap.

6. The powder path planning method for multi-material additive manufacturing based on powder bed according to claim 1, wherein, In the step SS2, the generation and filling of the single road line L(z) are realized through a path generation algorithm based on Bezier curve or B-spline curve, to ensure the smoothness and continuity of the filling path, and improve the efficiency and accuracy of the powder feeding operation.

7. The powder path planning method for multi-material additive manufacturing based on powder bed according to claim 1, wherein, In the step SS3, the zigzag filling strategy adopts an optimization method based on genetic algorithm, according to the geometric characteristics and constraint conditions in the remaining unfilled area R(z), using the adaptability evaluation, selection, crossover and mutation operations of genetic algorithm to find the optimal zigzag filling scheme and generate the corresponding filling vector set V(z).

8. The powder path planning method for multi-material additive manufacturing based on powder bed of claim 1, wherein, In the step SS3, the generation of the filling vector is realized by applying a path generation technology based on vector field, to ensure the continuity and uniformity of the filling path.

9. The powder path planning method for multi-material additive manufacturing based on powder bed of claim 1, wherein, In the step SS4, the overall offset processing adopts a simulation method based on finite element analysis technology, according to the geometric parameters and physical parameters in the powder feeding path set P(z), using finite element analysis technology to simulate and calculate various influencing factors in the powder feeding process, and obtain the best overall offset d, to improve the accuracy and efficiency of the powder feeding path planning.

10. The powder path planning method for multi-material additive manufacturing based on powder bed of claim 1, wherein, In the step SS5, before moving one slice thickness h in the slice height z direction, the powder feeding path set P(z) of the current layer is evaluated, a multi-objective optimization technology is applied to evaluate the powder feeding path set P(z), and the powder feeding path set P(z) is adjusted and optimized according to the evaluation result, to at least balance multiple objective functions including the length, time, energy consumption and quality of the powder feeding path.

Images