A global continuous path construction method based on combined contours and zigzag

Abstract

This invention discloses a global continuous path construction method based on combined contours and zigzag, belonging to the field of additive manufacturing. The method includes the following steps: S1, generating path elements, which include an outer contour, an intermediate contour, and the parallel lines to be clipped; S2, grouping path elements: grouping the outer contour and the intermediate contour, and then assigning the parallel lines to be clipped to the corresponding outer contour or intermediate contour according to the slice contour; S3, local connection: performing local connections on elements within the same group, first connecting the intermediate contour to the parallel lines to be clipped, and then connecting the connection result to the outer contour to obtain the local connection result; S4, constructing a global continuous trajectory: globally connecting all the curves obtained from the local connections to obtain a continuous path. This invention, using the above-mentioned global continuous path construction method based on combined contours and zigzag, can generate a global continuous trajectory for arbitrary shapes while simultaneously ensuring internal density and contour accuracy.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a method for constructing global continuous paths based on composite contours and zigzag. Background Technology

[0002] Wafer arc additive manufacturing (WAAM) is a crucial technology in directional energy deposition (DED) for producing large metal parts. It is favored due to its high cost-effectiveness and high deposition rate. However, its application is limited to parts of moderate complexity, as reliable printing of complex, multi-branch geometries remains under investigation. A suitable path planning algorithm is essential for manufacturing complex geometries, ensuring minimal defects, maximized efficiency, and stability. Global continuous path planning has proven to be the optimal approach, as it reduces arc start-up and extinguishing defects, eliminates idle travel, and ensures stable forming.

[0003] In the field of additive and subtractive manufacturing, the shapes of parts are becoming increasingly complex, while current continuous path methods can only be applied to simple shapes; on the other hand, the generated continuous path methods are difficult to guarantee both internal density and contour accuracy at the same time. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a global continuous path construction method based on combined contours and zigzag, which can generate a global continuous trajectory for any shape while simultaneously ensuring internal density and contour accuracy.

[0005] To achieve the above objectives, this invention provides a method for constructing a globally continuous path based on combined contours and zigzag, comprising the following steps:

[0006] S1. Generate path elements: Slice the 3D curved surface model of the part to be formed to obtain the slice outline of the part to be formed, and then generate a variety of path elements based on the slice outline. The path elements include the outer contour, the middle contour and the cut parallel lines.

[0007] S2, Path Element Grouping: Group the outer contour and the middle contour, and then divide the cut parallel lines into the corresponding outer contour or middle contour according to the slice contour.

[0008] S3, Local Connection: To perform local connection on elements within the same group, first connect the middle contour to the parallel line being clipped, and then connect the connection result to the outer contour to obtain the local connection result.

[0009] S4. Construct a global continuous trajectory: Connect all locally connected curves globally to obtain a continuous path.

[0010] Preferably, step S1 specifically includes the following steps:

[0011] S11. By calculating the depth of each polygon on the slice outline, the polygons on the slice outline are divided into inner polygons and outer polygons. Then the offset direction is determined. That is, when the slice outline is offset inward, the inner polygons are offset outward and the outer polygons are offset inward; when the slice outline is offset outward, the inner polygons are offset inward and the outer polygons are offset outward. The depth is the number of other polygons surrounding the current polygon.

[0012] S12. Taking into account heat shrinkage and machining, reserve a set post-processing allowance, and then offset the polygon inward by a set distance to obtain the outer contour.

[0013] S13. Based on the overlap rate w and the weld width p, the polygon is initially reduced by a set distance to ensure that the current weld overlaps with the existing weld without defects and to obtain the intermediate contour.

[0014] S14. Using the highest and lowest points of the slice outline as two reference points, generate multiple parallel lines from bottom to top with a distance of w*p between adjacent parallel lines.

[0015] S15. Use the middle outline to cut the parallel lines, and then reduce the length of each end of the cut parallel lines by w*p to obtain the cut parallel lines.

[0016] Preferably, in step S11, polygons with an even depth number are designated as external polygons, and polygons with an odd depth number are designated as internal polygons; and the vertices of the external polygons are sorted in a counterclockwise direction, and the vertices of the internal polygons are sorted in a clockwise direction.

[0017] Preferably, based on the weld width w and the overlap ratio p, the distance of the outer polygon shifting inward is calculated as w*p, and the distance of the inner polygon shifting outward is calculated as w*p; and the vertices of the middle contour are arranged clockwise.

[0018] Preferably, step S2 specifically includes the following steps:

[0019] S21. Create a new group for each intermediate contour and add the outer contour to the new group;

[0020] S22. Use linear interpolation to interpolate the current intermediate contour line;

[0021] S23. For each line segment on the intermediate contour line, recursively traverse all clipping line segments and add all clipping line segments to the intermediate contour in order to facilitate subsequent connection into a zigzag shape: if the starting point of the clipping line segment is on the line segment of the current iteration, add the clipping line segment and the contour vertex on the intermediate contour line; otherwise, only add the contour vertex on the intermediate contour.

[0022] Preferably, in step S22, the interpolation distance is less than w*p to ensure that each line segment on the intermediate contour has only one parallel line that is clipped.

[0023] Preferably, step S3 specifically includes the following steps:

[0024] S31. The intermediate contours are connected according to the following conditions to form a zigzag shape:

[0025] Create a zigzag outline and add elements to the middle outline based on conditions. Set the condition for the far outline to |Y2-Y1|<w*p, where Y1 represents the coordinates of the final point of the current zigzag outline; Y2 represents the coordinates of the next outline.

[0026] Probe forward from the current endpoint to determine if the next distant contour that meets the set conditions exists. If it does not exist, add the endpoint of the contour vertex to the contour zigzag. If it exists, select the current endpoint of the contour zigzag and add it to the start or end point based on the nearest principle to obtain the combined contour.

[0027] S32. Connection result and outer contour connection: Connect the outer contour using the combined contour to obtain the local connection result.

[0028] The present invention has the following beneficial effects:

[0029] 1. By adjusting the algorithm implementation steps, path elements are generated first and then the region is divided, thus avoiding the complexity of feature point selection when prioritizing contour segmentation;

[0030] 2. The path elements are simplified into three types, which facilitates the combination and classification of elements and optimizes the redundancy of element classification;

[0031] 3. The decomposition of contour feature information is transformed into grouping of inner and outer contours, which breaks through the shortcomings of traditional methods that can only be applied to a single feature or a single shape. Therefore, this algorithm can be applied to any complex shape.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] Figure 1 This is a flowchart of the global continuous path construction method based on combined contours and zigzag of the present invention;

[0034] Figure 2 This is a schematic diagram illustrating the generation of path elements according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the path element grouping constructed according to an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram showing the connection between the constructed intermediate contour and the cutting parallel line as described in an embodiment of the present invention.

[0037] Figure 5 This is a schematic diagram showing the connection between the intermediate result of the previous step and the outer contour as described in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the continuous trajectory constructed according to an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0040] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0041] Similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0042] As shown in the figure, the method for constructing a global continuous path based on combined contours and zigzag includes the following steps:

[0043] S1. Generate path elements: Slice the 3D curved surface model of the part to be formed to obtain the slice outline of the part to be formed, and then generate a variety of path elements based on the slice outline. The path elements include the outer contour, the middle contour and the cut parallel lines.

[0044] Step S1 specifically includes the following steps:

[0045] S11. By calculating the depth of each polygon on the slice outline, the polygons on the slice outline are divided into inner polygons and outer polygons. Then the offset direction is determined. That is, when the slice outline is offset inward, the inner polygons are offset outward and the outer polygons are offset inward; when the slice outline is offset outward, the inner polygons are offset inward and the outer polygons are offset outward. The depth is the number of other polygons surrounding the current polygon.

[0046] In step S11, polygons with an even depth number are designated as external polygons, and polygons with an odd depth number are designated as internal polygons; the vertices of the external polygons are sorted in a counterclockwise direction, and the vertices of the internal polygons are sorted in a clockwise direction.

[0047] S12. Taking into account heat shrinkage and machining, reserve a set post-processing allowance to ensure machining allowance and contour accuracy, and then offset the polygon inward by a set distance to obtain the outer contour.

[0048] S13. Based on the overlap rate w and the weld width p, the polygon is initially reduced by a set distance to ensure that the current weld overlaps with the existing weld without defects and to obtain the intermediate contour.

[0049] Preferably, in step S13, based on the weld width w and the overlap ratio p, the inward offset distance of the outer polygon is calculated as w*p, and the outward offset distance of the inner polygon is calculated as w*p; and the vertices of the middle contour are arranged clockwise.

[0050] S14. Using the highest and lowest points of the slice outline as two reference points, generate multiple parallel lines from bottom to top with a distance of w*p between adjacent parallel lines.

[0051] S15. Use the middle outline to cut the parallel lines, and then reduce the length of each end of the cut parallel lines by w*p to obtain the cut parallel lines.

[0052] S2, Path Element Grouping: Group the outer contour and the middle contour, and then divide the cut parallel lines into the corresponding outer contour or middle contour according to the slice contour.

[0053] Step S2 specifically includes the following steps:

[0054] S21. Create a new group for each intermediate contour, since the intermediate contour matches the outer contour, and add the outer contour to the new group;

[0055] S22. Use linear interpolation to interpolate the current intermediate contour line;

[0056] In step S22, the interpolation distance is less than w*p to ensure that each line segment on the intermediate contour has only one parallel line that is clipped.

[0057] S23. For each line segment on the intermediate contour line, recursively traverse all clipping line segments and add all clipping line segments to the intermediate contour in order to facilitate subsequent connection into a zigzag shape: if the starting point of the clipping line segment is on the line segment of the current iteration, add the clipping line segment and the contour vertex on the intermediate contour line; otherwise, only add the contour vertex on the intermediate contour.

[0058] S3, Local Connection: To perform local connection on elements within the same group, first connect the middle contour to the parallel line being clipped, and then connect the connection result to the outer contour to obtain the local connection result.

[0059] Step S3 specifically includes the following steps:

[0060] S31. The intermediate contours are connected according to the following conditions to form a zigzag shape:

[0061] Create a zigzag outline and add elements to the middle outline based on conditions. Set the condition for the far outline as |Y2-Y1|<w*p, where Y1 represents the coordinates of the final point of the current zigzag outline; Y2 represents the coordinates of the outline.

[0062] Probe forward from the current endpoint to determine if the next distant contour that meets the set conditions exists. If it does not exist, add the endpoint of the contour vertex to the contour zigzag. If it exists, select the current endpoint of the contour zigzag and add it to the start or end point based on the nearest principle to obtain the combined contour.

[0063] S32. Connection result and outer contour connection: Connect the outer contour using the combined contour to obtain the local connection result.

[0064] S4. Construct a global continuous trajectory: Connect all locally connected curves globally to obtain a continuous path.

[0065] Example:

[0066] (1) Generate path elements: Calculate the depth of each polygon and divide the polygons into internal and external polygons based on the depth; offset all polygons inward, setting the offset to 0 in the graph to obtain a machining allowance of half a weld width; offset all polygons inward again by half a weld pass; obtain parallel lines based on the highest and lowest points of the original contour shape, and trim them using slice contours to obtain the following... Figure 2 The path element generated graph is shown.

[0067] (2) Grouping of path elements

[0068] Group the outer contour and the middle contour; then assign parallel lines to either the outer contour or the middle contour. By traversing each line segment on each polygon, if the starting point of a clipping parallel line is on the outer contour or the middle contour, add it to the corresponding outer contour or middle contour, resulting in... Figure 3 The grouping results are shown.

[0069] (3) Local connectivity

[0070] First, probe forward from the current endpoint to determine if the next distant contour that meets the set conditions exists. If it does not exist, add the endpoint of the contour vertex to the zigzag contour. If it exists, select the current endpoint of the zigzag contour and add it to the start or end point based on the nearest neighbor principle, resulting in, as shown below. Figure 4 The combined contour shown; connection result with the outer contour: using the combined contour to connect the outer contour, the result is as follows. Figure 5 The local connection results shown

[0071] (4) Global Link

[0072] Since the groups are already continuous and the groups are adjacent, connecting the adjacent groups sequentially will yield the following result: Figure 6 The global continuous trajectory is shown.

[0073] Therefore, the present invention employs the above-mentioned global continuous path construction method based on combined contours and zigzag, which can generate global continuous trajectories for arbitrary shapes while ensuring both internal density and contour accuracy.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A global continuous path construction method based on combined contours and zigzag, applied to arc additive manufacturing, characterized by: Includes the following steps: S1. Generate path elements: Slice the 3D curved surface model of the part to be formed to obtain the slice outline of the part to be formed, and then generate a variety of path elements based on the slice outline. The path elements include the outer contour, the middle contour and the cut parallel lines. S2, Path Element Grouping: Group the outer contour and the middle contour, and then divide the cut parallel lines into the corresponding outer contour or middle contour according to the slice contour. S3, Local Connection: To perform local connection on elements within the same group, first connect the middle contour to the parallel line being clipped, and then connect the connection result to the outer contour to obtain the local connection result. S4. Construct a global continuous trajectory: Connect all locally connected curves globally to obtain a continuous path; Step S1 specifically includes the following steps: S11. By calculating the depth of each polygon on the slice outline, the polygons on the slice outline are divided into inner polygons and outer polygons. Then the offset direction is determined. That is, when the slice outline is offset inward, the inner polygons are offset outward and the outer polygons are offset inward; when the slice outline is offset outward, the inner polygons are offset inward and the outer polygons are offset outward. The depth is the number of other polygons surrounding the current polygon. S12. Taking into account heat shrinkage and machining, reserve a set post-processing allowance, and then offset the polygon inward by a set distance to obtain the outer contour. S13. Based on the overlap rate w and the weld width p, the polygon is initially reduced by a set distance to ensure that the current weld overlaps with the existing weld without defects and to obtain the intermediate contour. S14. Using the highest and lowest points of the slice profile as two reference points, generate two adjacent parallel lines from bottom to top, with the distance between them equal to... Multiple parallel lines; S15. Use the middle outline to cut the parallel lines, and then reduce the length of each end of the cut parallel lines. , to obtain the clipped parallel lines; In step S11, polygons with an even depth number are designated as external polygons, and polygons with an odd depth number are designated as internal polygons; and the vertices of the external polygons are sorted in a counterclockwise direction, while the vertices of the internal polygons are sorted in a clockwise direction. In step S13, based on the weld width p and the overlap ratio w, the inward offset distance of the outer polygon is calculated as follows: The distance by which the inner polygon is offset outward is And arrange the vertices of the middle outline clockwise.

2. The global continuous path construction method based on combined contours and zigzag as described in claim 1, characterized in that: Step S2 specifically includes the following steps: S21. Create a new group for each intermediate contour and add the outer contour to the new group; S22. Use linear interpolation to interpolate the current intermediate contour line; S23. For each line segment on the intermediate contour line, recursively traverse all clipping line segments and add all clipping line segments to the intermediate contour in order to facilitate subsequent connection into a zigzag shape: if the starting point of the clipping line segment is on the line segment of the current iteration, add the clipping line segment and the contour vertex on the intermediate contour line; otherwise, only add the contour vertex on the intermediate contour line.

3. The global continuous path construction method based on combined contours and zigzag as described in claim 2, characterized in that: In step S22, the interpolation distance is less than This ensures that each line segment on the middle contour has only one parallel line that is cut off.

4. The global continuous path construction method based on combined contours and zigzag as described in claim 3, characterized in that: Step S3 specifically includes the following steps: S31. The intermediate contours are connected according to the following conditions to form a zigzag shape: Create a zigzag outline, add elements to the middle outline based on conditions, and set the conditions for the far outline as follows. ,in, Indicates the coordinates of the final point of the current zigzag outline; The coordinates representing the next contour; Probe forward from the current endpoint to determine if the next distant contour that meets the set conditions exists. If it does not exist, add the endpoint of the contour vertex to the contour zigzag. If it exists, select the current endpoint of the contour zigzag and add it to the start or end point based on the nearest principle to obtain the combined contour. S32. Connection result and outer contour connection: Connect the outer contour using the combined contour to obtain the local connection result.

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