Special-shaped thin-wall part machining path identification method for laser cutting application

Abstract

The invention discloses a special-shaped thin-wall part machining path identification method for laser cutting application. The method comprises the steps of obtaining three-dimensional model data of the special-shaped thin-wall part, performing topological integrity processing on the special-shaped thin-wall part to obtain new three-dimensional model data, then obtaining an ordered topological surface set, traversing the ordered topological surface set to obtain a seed outer wall surface, and obtaining the wall thickness of the special-shaped thin-wall part according to the seed outer wall surface. And traversing adjacent topological surfaces from the outer wall surface of the seed in a breadth-first search manner to obtain a searched outer wall surface set, and finally, obtaining all processing path sets according to the searched outer wall surface set. According to the method, the correctness of the topological structure of the model is ensured by performing connectivity pre-checking and topological updating on the three-dimensional model data, and the processing path of the three-dimensional model is accurately obtained by adopting a strategy of combining model outer wall surface set recognition and directed edge circulation search.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of industrial part manufacturing, and particularly relates to a special-shaped thin-walled part machining path recognition method for laser cutting application. BACKGROUND

[0002] As an advanced processing method, laser cutting technology has the advantages of high processing speed, high precision and strong flexibility, and has been widely used in the processing of thin-walled parts in the fields of medical devices, electronic products, automobile manufacturing, aerospace, etc. However, in actual production, due to the various structural forms and complex cutting profiles of thin-walled parts, the traditional laser cutting processing system cannot automatically recognize the machining features of the workpiece, and still needs to rely on manual selection of machining features, which seriously restricts the improvement of processing efficiency and intelligent level.

[0003] For example, Chinese invention patent CN110795797A discloses a machining feature recognition and information extraction method based on MBD model, which uses the topological information of the model to construct a feature subgraph, and completes the recognition by matching the feature subgraph with a predefined machining feature type subgraph. However, due to the dependence on the predefined subgraph, this method cannot recognize unknown rule machining features. Chinese invention patent CN110837694A discloses a rotary machining feature recognition method, which determines the machining feature by recognizing the rotary surface in the part, but is only applicable to rotary machining scenarios, with limited scope of application.

[0004] In addition, in actual user data, three-dimensional models may be represented in the form of a combination of multiple independent surfaces in addition to being described in the form of a closed shell, and their topological structure is not necessarily correct. These factors all lead to the fact that the prior art lacks an efficient, accurate and widely applicable automatic machining feature recognition method when dealing with three-dimensional laser cutting of special-shaped thin-walled parts. SUMMARY

[0005] In order to solve the problems in the background art, the present application provides a special-shaped thin-walled part machining path recognition method for laser cutting application, which solves the technical problem of lacking machining path recognition for special-shaped thin-walled parts in the prior art. The method proposed in the present application can efficiently and accurately extract the machining feature information of the part, significantly improve the accuracy and robustness of feature recognition, and reduce manual intervention, thereby overcoming the deficiencies in the prior art.

[0006] The technical solution adopted by the present application is: One, a special-shaped thin-walled part machining path recognition method for laser cutting application: S1. Obtain the 3D model data of the irregular thin-walled part, and perform topological integrity processing on the irregular thin-walled part by traversing all the topological edges of the irregular thin-walled part from the 3D model data to obtain new 3D model data of the irregular thin-walled part.

[0007] S2. Calculate the absolute area of ​​each topological surface in the new 3D model data using an area integrator, and sort the topological surfaces in descending order of absolute area to obtain an ordered set of topological surfaces.

[0008] S3. Traverse the ordered set of topological faces, obtain the interior points of the current topological face, obtain the total number of intersections between the rays emanating from the interior points and all other topological faces, and obtain the seed outer wall face based on the total number of intersections.

[0009] S4. Obtain the wall thickness of the irregular thin-walled part based on the outer wall surface of the seed.

[0010] S5. Starting from the seed outer wall, traverse the adjacent topological surfaces in a breadth-first search manner to obtain the newly added outer wall. After the breadth-first search is completed, all outer wall surfaces are summarized to obtain the searched outer wall set.

[0011] S6. Based on the topological connection relationship, filter out all wall boundary topological edges from all the topological edges of all the outer walls in the outer wall set. Summarize all the wall boundary topological edges to obtain the wall boundary topological edge set. Perform processing path acquisition processing on the wall boundary topological edge set to obtain the set of all processing paths.

[0012] The topological integrity processing specifically involves the following steps: if each topological edge is used by two topological faces, the topological connection relationship is correct, and the original 3D model data is used as the new 3D model data; if a topological edge is used by only one topological face, the topological connection relationship is incorrect, and the 3D model data is updated to obtain new 3D model data.

[0013] The specific process for updating the topological connectivity is as follows: Let C be a topological edge that is currently used by only one topological surface. i Traverse to find another topological edge C j Determine the topological edge C i and topological edge C j Does the three-point matching condition satisfy? If the three-point matching condition is satisfied, then the topological edge C... i and topological edge C j Match successful, end traversal and update topological edge C. i and topological edge C j Connect the topological surfaces respectively; if the three-point matching condition is not satisfied, then the topological edge C i and topological edge C j If a match is not found, continue iterating until a match is found.

[0014] The updated topology edge C i and topological edge C j The specific connection of the topological surfaces is as follows: connect the topological edges C j The connected topological surfaces are called topological edges C i Connecting topological surfaces, including topological edges C i The connected topological surfaces are called topological edges C j Connected topological surfaces.

[0015] The three-point matching condition is: if the topological edge C i and topological edge C j If the two endpoints and the midpoint are all equal, then the topological edge C i and topological edge C j If they are the same topological edge, then a successful match is achieved; otherwise, topological edge C... i and topological edge C j The edges are not from the same topology, so the match failed.

[0016] Step S3 specifically involves: traversing each topological surface in the ordered set of topological surfaces, obtaining the interior point of the current topological surface, emitting a ray from the interior point along the surface normal of the current topological surface, and obtaining the total number of intersections between the ray and all other topological surfaces except the current topological surface; obtaining the seed outer wall surface based on the total number of intersections: when the number of intersections is 0, the traversal ends and the current topological surface is the seed outer wall surface; when the number of intersections is not 0, the traversal of topological surfaces continues until the seed outer wall surface is found.

[0017] To obtain the interior point of the current topological surface, the following steps are taken: Obtain the midpoint of the longest topological edge in the topological surface. Obtain the surface normal N of the midpoint on the topological surface and the tangent vector T on the longest topological edge. Obtain the vector D pointing into the interior of the topological surface by cross product of the surface normal N and the tangent vector T. Draw a ray from the midpoint along the vector D to obtain all intersection points of the ray with the other topological edges on the topological surface except for the longest topological edge. Take the intersection point that is closest to the midpoint of the longest topological edge. The midpoint of the line connecting the midpoint of the longest topological edge and the closest intersection point is the interior point of the current topological surface.

[0018] Step S4 specifically involves: emitting a ray from the inner point corresponding to the seed outer wall surface in the opposite direction of the surface normal of the seed outer wall surface, obtaining all intersection points of the ray with other topological surfaces except the seed outer wall surface, taking the topological surface containing the intersection point closest to the inner point as the inner wall surface corresponding to the seed outer wall surface, and calculating the wall thickness of the irregular thin-walled part using the Hausdorff distance formula based on the seed outer wall surface and the corresponding inner wall surface.

[0019] Step S5 specifically involves: adding the seed outer wall to the initialized empty outer wall set; traversing adjacent topological faces using a breadth-first search starting from the seed outer wall; when traversing each topological face, traversing all topological edges of the current topological face; when traversing each topological edge, obtaining the other topological face containing the current topological edge (excluding the current topological face), and marking the obtained topological face as the second topological face of the current topological edge; obtaining the thickness width of the second topological face of the current topological edge; adding the second topological face with a thickness width greater than the wall thickness as a new outer wall and adding it to the outer wall set, until there are no new outer wall faces in the outer wall set, at which point the breadth-first search ends and the searched outer wall set is obtained.

[0020] The specific steps for obtaining the thickness width of the second topological surface of the current topological edge are as follows: obtain the midpoint of the current topological edge, obtain the surface normal of the midpoint on the second topological surface and the tangent vector on the current topological edge, obtain the in-plane vector pointing into the second topological surface by cross product of the surface normal and the tangent vector, emit a ray from the midpoint of the current topological edge along the in-plane vector, obtain all intersection points of the ray with the other topological edges on the second topological surface except for the current topological edge, and obtain the distance between the intersection point farthest from the midpoint of the current topological edge as the thickness width of the second topological surface.

[0021] The specific processing steps for obtaining the processing path are as follows: all topological edges in the wall boundary topological edge set are divided into the in-plane topological edge set and the edge topological edge set, respectively; for the in-plane topological edge set, each in-plane topological edge is a circular processing path, thus the in-plane topological edge set becomes a circular processing path set; for the edge topological edge set, a directed edge search is performed on all edge topological edges within the set to obtain several directed connected lines, each of which is a directed processing path; all directed processing paths are summarized to obtain a directed processing path set; the circular processing path set and the directed processing path set are summarized to obtain a complete processing path set.

[0022] The wall boundary topological edge is the topological edge used by a single outer wall surface; the in-plane topological edge is the topological edge located within the surface of the outer wall surface; the edge topological edge is the topological edge located at the edge of the outer wall surface.

[0023] The beneficial effects of this invention are: 1. This invention ensures the correctness of the model's topology by performing connectivity pre-checks and topology updates on the 3D model data; and accurately obtains the processing path of the 3D model by combining the identification of the model's outer wall set with the directed edge loop search strategy.

[0024] 2. In determining the set of outer wall surfaces, this invention combines the area comparison method and the ray method to accurately select the outer wall surfaces, ensuring the accuracy and reliability of the outer wall surface set identification. For models commonly found in actual production that consist of multiple facets, this invention further employs topological integrity processing to update the model's topological connections, thereby ensuring the correctness and stability of subsequent processing path calculations.

[0025] 3. Compared with the prior art, the present invention not only improves the accuracy and robustness of processing path recognition, but also effectively adapts to complex and diverse thin-walled part structures and non-ideal user data models, significantly reducing manual intervention and improving overall processing efficiency and automation level. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method of the present invention.

[0027] Figure 2 This is a schematic diagram of a three-dimensional model of the semi-circular thin-walled part in Example 1.

[0028] Figure 3 This is a seed outer wall view of the semi-circular thin-walled part in Example 1.

[0029] Figure 4 This is a diagram showing the outer wall surface and machining path of the semi-circular thin-walled part in Example 1.

[0030] Figure 5 This is a schematic diagram of a three-dimensional model of the coronary stent component in Example 2.

[0031] Figure 6 This is a diagram showing the outer wall surface and processing path of the coronary stent component in Example 2.

[0032] Figure 7 This is a schematic diagram of the topological edges of the wall boundary and the shared topological edges of the walls.

[0033] Figure 8 This is a schematic diagram of in-plane topological edges and edge topological edges. Detailed Implementation

[0034] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments. However, the present invention is not limited thereto. For those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

[0035] Related Terminology: **Irregular Thin-Walled Parts:** These refer to thin-walled parts that cannot be directly combined or described using simple stretched bodies (such as cuboids, cylinders, etc.). They possess irregular geometric shapes or complex variations in features. Their characteristics include maintaining a relatively thin overall profile, with cross-sectional shapes potentially changing along the axial direction. The overall shape may exhibit irregular three-dimensional forms such as twisting or bending. The outer and inner surfaces of the part are not connected. "Thin-walled" refers to the relatively thin wall thickness, typically within a small proportional range compared to the overall size of the part. **Outer Wall Surface:** This refers to the outer surface area of ​​an irregular thin-walled part, the surface that directly contacts the external environment. **Inner Wall Surface:** This refers to the inner surface area of ​​an irregular thin-walled part, possessing similar geometric features to the outer wall surface, approximately parallel and corresponding but in opposite directions. **Cut Surface:** This refers to the newly formed surface created during the cutting process, connecting the outer and inner wall surfaces of the irregular thin-walled part. **Machining Path:** This refers to the movement trajectory of machining tools (such as laser cutting heads, CNC cutting tools, etc.) according to a predefined spatial path to achieve a specific machining objective during the manufacturing process. Interior point: A point located inside a topological surface, not on a topological edge of the surface. Shared topological edge: A topological edge shared by two topological surfaces, both of which belong to the wall of a non-circular thin-walled part. Wall boundary topological edge: A topological edge used by one topological surface that belongs to the non-circular thin-walled part, or shared by two topological surfaces, but only one of which belongs to the wall of the non-circular thin-walled part. In-plane topological edge: A topological edge located within the surface of an outer wall. Edge topological edge: A topological edge located at the edge of an outer wall.

[0036] Example 1:

[0037] like Figure 1 As shown, the method for identifying the processing path of irregularly shaped thin-walled parts in this embodiment includes the following steps: S1. Obtain the 3D model data of the irregular thin-walled part, and perform topological integrity processing on the irregular thin-walled part by traversing all the topological edges of the irregular thin-walled part from the 3D model data to obtain new 3D model data of the irregular thin-walled part.

[0038] The topological integrity processing is as follows: if each topological edge in the 3D model data is used by two topological faces, then the topological connection relationship is correct, and the original 3D model data is used as the new 3D model data; if there is a topological edge in the 3D model data that is used by only one topological face, then the topological connection relationship is incorrect, and the 3D model data is updated to obtain new 3D model data.

[0039] The specific process for updating topological connectivity is as follows: Let C be the topological edge currently used by only one topological surface. i 1≤i≤q, where q is the number of all topological edges in the 3D model data. The search involves iterating through the data to find another topological edge C. j(1≤j≤q, i!=j), determine the topological edge C i and topological edge C j Does the three-point matching condition satisfy? If the three-point matching condition is satisfied, then the topological edge C... i and topological edge C j Match successful, end traversal and update topological edge C. i and topological edge C j Connect the topological surfaces respectively; if the three-point matching condition is not satisfied, then the topological edge C i and topological edge C j If a match is not found, continue iterating until a match is found.

[0040] Update topological edge C i and topological edge C j The specific connection of the topological surfaces is as follows: connect the topological edges C j The connected topological surfaces are called topological edges C i Connecting topological surfaces, including topological edges C i The connected topological surfaces are called topological edges C j Connected topological surfaces.

[0041] In practice, suppose there exists a topological edge C in the 3D model data that is used by only one topological surface. i And topological edge C i Let A be the connected topological surface; traverse the topological edges to find another topological edge C. j and topological edge C i The three matching conditions are met, thus the match is successful, and the topological edge C j The connected topological surface is surface B.

[0042] Then update the topological edge C. i and topological edge C j The connected topological surfaces are: topological edge C i Connecting topological surfaces A and B, topological surface C j The connected topological surfaces are surface A and surface B.

[0043] The three-point matching condition is: if the topological edge C i and topological edge C j If the two endpoints and the midpoint are all equal, then the topological edge C i and topological edge C j If they are the same topological edge, then a successful match is achieved; otherwise, topological edge C... i and topological edge C j The edges are not from the same topology, so the match failed.

[0044] The wall thickness of a single irregularly shaped thin-walled part remains within a certain range throughout the entire structure; therefore, in this embodiment, it is assumed that the wall thickness remains consistent across all locations. The three-dimensional model data of the irregularly shaped thin-walled part is represented using a boundary representation method, which includes points, lines, and surfaces.

[0045] S2. Calculate the absolute area of ​​each topological surface in the new 3D model data using the existing area integrator, and sort the topological surfaces in descending order of absolute area to obtain an ordered set of topological surfaces.

[0046] S3. Traverse the ordered set of topological faces, obtain the interior points of the current topological face, obtain the total number of intersections between the rays emanating from the interior points and all other topological faces, and obtain the seed outer wall face based on the total number of intersections.

[0047] Step S3 is as follows: Traverse each topological surface in the ordered set of topological surfaces, obtain the interior point of the current topological surface, emit a ray from the interior point along the surface normal of the current topological surface, and obtain the total number of intersections between the ray and all other topological surfaces in the ordered set (excluding the current topological surface); obtain the seed outer wall surface based on the total number of intersections: when the number of intersections is 0, the traversal ends and the current topological surface is the seed outer wall surface; when the number of intersections is not 0, continue traversing the topological surfaces until the seed outer wall surface is found.

[0048] To obtain the interior point of the current topological surface, the following steps are taken: Obtain the midpoint of the longest topological edge in the topological surface. Obtain the surface normal N of the midpoint on the topological surface and the tangent vector T on the longest topological edge. Obtain the vector D pointing into the interior of the topological surface by cross product of the surface normal N and the tangent vector T. Draw a ray from the midpoint of the longest topological edge along the vector D. Obtain all intersection points of the ray with the other topological edges on the topological surface except for the longest topological edge. Take the intersection point that is closest to the midpoint of the longest topological edge. The midpoint of the line connecting the midpoint of the longest topological edge and the closest intersection point is the interior point of the current topological surface.

[0049] In this embodiment, the specific steps for obtaining the interior points of the topological surface are: finding the longest topological edge C in the topological surface. 3d Given (t)=(x(t),y(t),z(t)), find the longest topological edge C. 3d The one-dimensional parameter domain of (t) is [t1, t2], and the midpoint of the one-dimensional parameter domain is t. mid =(t1+t2) / 2; The longest topological edge C 3d (t) is represented by the two-dimensional curve on the topological surface as C. 2d (k)=(u(k),v(k)), two-dimensional curve C 2d The one-dimensional parameter domain corresponding to (u(k),v(k)) is [k1,k2], and the midpoint of the one-dimensional parameter domain is k. mid =(k1+k2) / 2; Longest topological edge C3d The tangent vector of the midpoint of (t) on the longest topological edge is T=C. 3d ′(t mid Longest topological edge C 3d The midpoint of (t) corresponds to the midpoint of the two-dimensional parameter domain, which is P=C. 2d (k mid )=(u(k mid ),v(k mid Let the topological surface be S(u,v). Based on point P in the two-dimensional parameter domain, the corresponding parameter on the topological surface is (u...). mid ,v mid ), calculate the surface normal N=S of point P on the topological surface in the two-dimensional parameter domain. u ′(u mid ,v mid )×S v ′(u mid ,v mid The vector D pointing into the interior of the topological surface is calculated using D=N×T; starting from the longest topological edge C... 3d A ray is drawn from the midpoint of (t) along vector D, and the intersection of the ray and the topological surface is obtained except for the longest topological edge C. 3d Find all intersections with other topological edges besides (t), and obtain the longest topological edge C. 3d The midpoint of (t) is the nearest intersection point, and the longest topological edge C is... 3d The midpoint of the line connecting the midpoint of (t) and the nearest intersection point is the interior point of the current topological surface.

[0050] Furthermore, when the ray intersects the topological surface except for the longest topological edge C... 3d When there are no intersection points for other topological edges besides (t), the calculation is changed to be performed in the topological surface parameter domain, thus transforming it into a planar calculation, and the intersection points will basically exist; (the calculation method is similar, the difference is that the intersection of the three-dimensional ray with other topological edges is changed to the intersection of the two-dimensional ray with the two-dimensional curves corresponding to other topological edges.) The calculation method is as follows: find the longest topological edge C in the topological surface. 3d (t), the longest topological edge C 3d (t) is represented by the two-dimensional curve on the topological surface as C. 2d (k)=(u(k),v(k)), two-dimensional curve C 2d The one-dimensional parameter domain corresponding to (u(k),v(k)) is [k1,k2], and the midpoint of the one-dimensional parameter domain is k. mid =(k1+k2) / 2, the midpoint of the longest topological edge corresponds to the midpoint of the two-dimensional parameter domain, which is P=C. 2d (k mid )=(u(k mid ),v(k mid ), Tangent vector T=C2d ′(k mid The surface normal N=(0,0,1), and the vector D pointing into the interior of the topological surface is calculated according to D=N×T; from the longest topological edge C 2d A ray is drawn from the midpoint of (k) along vector D, and the intersection of the ray and the topological surface is obtained except for the longest topological edge C. 2d For all intersection points of the two-dimensional curves corresponding to the other topological edges besides (k), obtain the intersection points with the longest topological edge C. 2d The midpoint of (k) is closest to the intersection point, and the longest topological edge C is... 2d M(u) is the midpoint of the line connecting the midpoint of (k) and the nearest intersection point. m ,v m The interior point of the current topological surface in the two-dimensional parameter domain is represented by the formula Inner = S(u). The corresponding interior point in the three-dimensional domain is calculated as Inner = S(u). m ,v m Since the two-dimensional parameter domain is the standard xoy coordinate system, z=0. Therefore, the surface normal is the z-axis, so the surface normal N=(0,0,1). If the intersection point still does not exist, the midpoint of the longest topological edge is used as the interior point.

[0051] In short, the calculation process for interior points is as follows: first, calculate in three dimensions (which usually exists); if the calculation of intersections in three dimensions fails, then calculate in two dimensions; if the calculation of intersections in two dimensions fails, finally use the midpoint of the longest topological edge as a fallback.

[0052] In practice, when representing points, lines, and surfaces in 3D model data, the orientation of the surfaces is already represented, so the direction of the surface normal of a topological surface is unique.

[0053] S4. Obtain the wall thickness of the irregular thin-walled part based on the outer wall surface of the seed.

[0054] Step S4 is as follows: A ray is emitted from the inner point corresponding to the seed outer wall surface in the opposite direction of the surface normal of the seed outer wall surface. All intersection points of the ray with other topological surfaces except the seed outer wall surface are obtained. The topological surface containing the intersection point closest to the inner point is taken as the inner wall surface corresponding to the seed outer wall surface. The wall thickness of the irregular thin-walled part is calculated using the Hausdorff distance formula based on the seed outer wall surface and the corresponding inner wall surface.

[0055] In practice: Uniform sampling is performed on the outer wall surface S1 and the corresponding inner wall surface S2 of the seed, resulting in two discrete point sets pts1 and pts2. According to the Hausdorff distance calculation formula: H(S1,S2)=max[h(S1,S2),h(S2,S1)], where h(S1,S2)=max[H(S1,S2),H(S2,S1)]. a∈pts1 min b∈pts2 ||ab||,h(S2,S1)=max b∈pts2 mina∈pts1 Substituting ||ba|| into the calculation, we can obtain the wall thickness H(S1,S2).

[0056] S5. Starting from the seed outer wall, traverse the adjacent topological surfaces in a breadth-first search manner to obtain the newly added outer wall. After the breadth-first search is completed, all outer wall surfaces are summarized to obtain the searched outer wall set.

[0057] Step S5 is as follows: Add the seed outer wall to the initialized empty outer wall set. Starting from the seed outer wall, traverse the adjacent topological faces using a breadth-first search. When traversing each topological face, traverse all topological edges of the current topological face. When traversing each topological edge, obtain the other topological face containing the current topological edge (excluding the current topological face) and mark it as the second topological face of the current topological edge. Obtain the thickness width of the second topological face of the current topological edge. Add the second topological face whose thickness width is greater than the wall thickness of the irregular thin-walled part as a new outer wall face to the outer wall set. Continue until there are no more new outer wall faces in the outer wall set. The breadth-first search ends and the searched outer wall set is obtained.

[0058] The specific steps to obtain the thickness width of the second topological face of the current topological edge are as follows: obtain the midpoint of the current topological edge, obtain the surface normal of the midpoint on the second topological face and the tangent vector on the current topological edge, obtain the in-plane vector pointing into the second topological face by cross product of the surface normal and the tangent vector, and emit a ray from the midpoint of the current topological edge along the in-plane vector to obtain all intersection points of the ray with the other topological edges on the second topological face except for the current topological edge. Obtain the distance between the intersection point farthest from the midpoint of the current topological edge as the thickness width of the second topological face.

[0059] In practice, if the ray does not intersect with any other topological edge on the second topological surface except for the current topological edge, it means that the second topological surface is not a cutting surface but an outer wall surface. Therefore, the second topological surface is directly added as a new outer wall surface and added to the set of outer wall surfaces.

[0060] In practice, topological surfaces whose thickness width is less than or equal to the wall thickness of the irregular thin-walled part are considered cutting surfaces, and these cutting surfaces do not need to be added to the outer wall surface set. In practice, when traversing each topological edge, if there is only one topological surface containing the topological edge, no processing is performed.

[0061] S6. Based on the topological connection relationship, filter out all wall boundary topological edges from all topological edges of all outer walls in the outer wall set. Summarize all wall boundary topological edges to obtain the wall boundary topological edge set. Perform processing path acquisition on the wall boundary topological edge set to obtain the set of all processing paths.

[0062] The specific processing steps for obtaining processing paths are as follows: all topological edges in the wall boundary topological edge set are divided into the in-plane topological edge set and the edge topological edge set respectively; for the in-plane topological edge set, each in-plane topological edge is a circular processing path, thus the in-plane topological edge set becomes a circular processing path set; for the edge topological edge set, a directed edge search is performed on all edge topological edges within the set to obtain several directed connected lines, each of which is a directed processing path; all directed processing paths are summarized to obtain a directed processing path set; the circular processing path set and the directed processing path set are summarized to obtain a complete processing path set.

[0063] In this embodiment, the wall boundary topological edge is the topological edge used by a single outer wall (a topological edge belonging only to a single outer wall), as shown in the example. Figure 7 The two ends in blue are shown.

[0064] like Figure 8 As shown, in-plane topological edges are the topological edges located within the outer wall surface; edge topological edges are the topological edges located at the edges of the outer wall surface.

[0065] In practice, after filtering out all wall boundary topological edges, the remaining topological edges are all wall-shared topological edges. Since the topological faces connected by these wall-shared topological edges are not cutting faces, they are not processed. Wall-shared topological edges are topological edges used by both outer walls (belonging to the topological edges of both outer walls). Examples of wall-shared topological edges include... Figure 7 As shown in red.

[0066] All topological edges in the wall boundary topological edge set are unordered, so a directed edge search is required.

[0067] In practice, from a data perspective, each topological edge is formed by the directed connection of several directed line segments. An in-plane topological edge is a topological loop formed by the directed connection of several directed line segments; from a data perspective, the formed topological loop is the circular processing path. Similarly, edge topological edges are also formed by the directed connection of several directed line segments; from a data perspective, the data of these directed line segment connections constitutes the edge topological edge data. A directed processing path is formed by the directed search connection of the data of several edge topological edges.

[0068] Furthermore, after obtaining the set of all processing paths: fix the original part to be processed in a fixed position, and the machine processes the original part according to the set of processing paths to obtain the irregular thin-walled part.

[0069] Example 2:

[0070] This embodiment describes processing in the automotive manufacturing field, and considers parts with a wall thickness range of 0.8-1.6mm as thin-walled.

[0071] This embodiment uses the same steps as in Embodiment 1. Figure 2 The processing path of the semi-circular thin-walled part shown is identified, such as... Figure 3 The red wall in the image represents the outer wall of the seed. The obtained outer wall and processing path are shown below. Figure 4 As shown.

[0072] Example 3:

[0073] This embodiment describes the processing in the field of medical devices. In this embodiment, parts with a wall thickness range of 0.05-0.1mm are considered thin-walled.

[0074] The same steps as in Example 1 are applied to the following: Figure 5 The processing path of the shown coronary stent component is identified, and the resulting outer wall surface and processing path are as follows: Figure 6 As shown.

[0075] This invention ensures the correctness of the model's topology by performing connectivity pre-checks and topology updates on the 3D model data; and it accurately obtains the processing path of the 3D model by combining the identification of the model's outer wall set with a directed edge loop search strategy.

[0076] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications, characterized in that, Includes the following steps: S1. Obtain the 3D model data of the irregular thin-walled part, and perform topological integrity processing on the irregular thin-walled part by traversing all the topological edges of the irregular thin-walled part from the 3D model data to obtain new 3D model data of the irregular thin-walled part. S2. Calculate the absolute area of ​​each topological surface in the new 3D model data using an area integrator, and sort the topological surfaces in descending order of absolute area to obtain an ordered set of topological surfaces. S3. Traverse the ordered set of topological faces, obtain the interior points of the current topological face, obtain the total number of intersections between the rays emanating from the interior points and all other topological faces, and obtain the seed outer wall face based on the total number of intersections. S4. Obtain the wall thickness of the irregularly shaped thin-walled part based on the outer wall surface of the seed; S5. Starting from the seed outer wall, traverse the adjacent topological surfaces in a breadth-first search manner to obtain the newly added outer wall. After the breadth-first search is completed, all outer wall surfaces are summarized to obtain the searched set of outer wall surfaces. S6. Based on the topological connection relationship, filter out all wall boundary topological edges from all the topological edges of all the outer walls in the outer wall set. Summarize all the wall boundary topological edges to obtain the wall boundary topological edge set. Perform processing path acquisition processing on the wall boundary topological edge set to obtain the set of all processing paths.

2. The method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications according to claim 1, characterized in that, The topology integrity processing specifically involves: If each topological edge is used by two topological faces, the topological connection is correct, and the original 3D model data is used as the new 3D model data. If a topological edge is used by only one topological face, the topological connection is incorrect, and the 3D model data is updated to obtain new 3D model data.

3. The method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications according to claim 2, characterized in that, The specific process for updating the topology connection relationship is as follows: Let C be the topological edge that is currently used by only one topological surface. i Traverse to find another topological edge C j Determine the topological edge C i and topological edge C j Does the three-point matching condition satisfy? If the three-point matching condition is satisfied, then the topological edge C... i and topological edge C j Matching successful, end traversal and update topological edge C. i and topological edge C j Connect the topological surfaces respectively; if the three-point matching condition is not satisfied, then the topological edge C i and topological edge C j If a match is not found, continue iterating until a match is found.

4. The method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications according to claim 3, characterized in that: The updated topology edge C i and topological edge C j The specific connection of the topological surfaces is as follows: connect the topological edges C j The connected topological surfaces are called topological edges C i Connecting topological surfaces, including topological edges C i The connected topological surfaces are called topological edges C j Connected topological surfaces; The three-point matching condition is: if the topological edge C i and topological edge C j If the two endpoints and the midpoint are all equal, then the topological edge C i and topological edge C j If they are the same topological edge, then a successful match is achieved; otherwise, topological edge C... i and topological edge C j The edges are not from the same topology, so the match failed.

5. The method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications according to claim 1, characterized in that, Step S3 specifically involves: Traverse each topological face in the ordered set of topological faces, obtain the interior point of the current topological face, and emit a ray from the interior point along the normal of the current topological face. Obtain the total number of intersections between the ray and all other topological faces except the current topological face. Obtain the seed outer wall based on the total number of intersections: when the number of intersections is 0, the traversal ends and the current topological face is the seed outer wall; when the number of intersections is not 0, continue traversing the topological faces until the seed outer wall is found.

6. The method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications according to claim 5, characterized in that, The specific steps to obtain the interior points of the current topological surface are as follows: Find the midpoint of the longest topological edge in the topological plane. Find the plane normal N of the midpoint on the topological plane and the tangent vector T on the longest topological edge. Obtain the vector D pointing into the topological plane by cross product of plane normal N and tangent vector T. Draw a ray from the midpoint along vector D and obtain all intersection points of the ray with the other topological edges on the topological plane except for the longest topological edge. Take the intersection point that is closest to the midpoint of the longest topological edge. The midpoint of the line connecting the midpoint of the longest topological edge and the nearest intersection point is the interior point of the current topological plane.

7. The method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications according to claim 1, characterized in that, Step S4 specifically involves: A ray is emitted from the inner point corresponding to the seed outer wall surface in the opposite direction of the surface normal of the seed outer wall surface. All intersection points of the ray with other topological surfaces except the seed outer wall surface are obtained. The topological surface containing the intersection point closest to the inner point is taken as the inner wall surface corresponding to the seed outer wall surface. The wall thickness of the irregular thin-walled part is calculated using the Hausdorff distance formula based on the seed outer wall surface and the corresponding inner wall surface.

8. The method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications according to claim 1, characterized in that, Step S5 specifically involves: Add the seed outer wall to the initially empty outer wall set. Starting from the seed outer wall, traverse the adjacent topological faces using a breadth-first search. When traversing each topological face, traverse all topological edges of the current topological face. When traversing each topological edge, obtain the other topological face containing the current topological edge (excluding the current topological face) and mark it as the second topological face of the current topological edge. Obtain the thickness width of the second topological face of the current topological edge. Add the second topological face whose thickness width is greater than the wall thickness as a new outer wall face to the outer wall set. Continue until there are no more new outer wall faces in the outer wall set. The breadth-first search ends, and the searched outer wall set is obtained.

9. A method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications, as described in claim 8, is characterized in that... The specific method for obtaining the thickness width of the second topological face of the current topological edge is as follows: Obtain the midpoint of the current topological edge, and obtain the surface normal and tangent vector of the midpoint on the second topological surface. Obtain the in-plane vector pointing into the second topological surface by cross product of the surface normal and tangent vector. Draw a ray from the midpoint of the current topological edge along the in-plane vector, and obtain all intersection points of the ray with the other topological edges on the second topological surface except for the current topological edge. Obtain the distance between the intersection point farthest from the midpoint of the current topological edge as the thickness width of the second topological surface.

10. A method for identifying the processing path of irregularly shaped thin-walled parts for laser cutting applications, as described in claim 1, is characterized in that... The specific process for obtaining the processing path is as follows: All topological edges in the wall boundary topological edge set are respectively divided into the in-plane topological edge set and the edge topological edge set. For the in-plane topological edge set, each in-plane topological edge is a loop processing path, thus the in-plane topological edge set is a set of loop processing paths. For the edge topological edge set, a directed edge search is performed on all edge topological edges in the set to obtain several directed connected lines, each of which is a directed processing path. All directed processing paths are summarized to obtain the set of directed processing paths. The set of loop processing paths and the set of directed processing paths are summarized to obtain the set of all processing paths. The wall boundary topological edge is the topological edge used by a single outer wall surface; the in-plane topological edge is the topological edge located within the surface of the outer wall surface; the edge topological edge is the topological edge located at the edge of the outer wall surface.

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