An automatic generation method of 3D part dimensioning based on MBD

Abstract

The present invention discloses a method for automatically generating three-dimensional part dimension annotation based on MBD. The method first performs a structural analysis on the topological object of a geometric body, extracts all boundary elements on the geometric body, and traverses each boundary element in the set to analyze the related topological structure and geometric surface, completes screening, filtering and classification, and obtains a set of annotation elements of various types; secondly, for different types of annotation elements, analyzes the qualitative positioning association between the annotation elements and the dimensions, and designs a corresponding dimension annotation algorithm; then, creates an annotation plane according to the requirements of dimension generation, and performs repeated judgment with the existing annotation view set; finally, completes the rapid generation of dimension information, performs a redundancy check on the generated annotation information, removes redundant dimensions, and realizes the construction of a three-dimensional inspection model. The present invention can directly express part manufacturing and inspection information on the three-dimensional model, improves product development efficiency, and shortens the production cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional annotation of three-dimensional part models in a design process, and in particular to a method for automatically generating three-dimensional part dimension annotation based on MBD. Background Art

[0002] In recent years, with the rapid development of my country's aviation manufacturing industry, digitalization and intelligentization have become new trends in future aviation industry technological advancements. Although part design has achieved three-dimensionalization, domestic inspection methods based on model-based definition (MBD) technology are still relatively backward. The mainstream inspection technology used by most aircraft manufacturers still relies on preparing inspection plans and expressing part dimensions and other information through two-dimensional drawings. This traditional inspection method is not only labor-intensive and inefficient, but also prone to errors during the actual inspection process. Today, the fully three-dimensional digital product development model has entered a new stage. Boeing has fully adopted MBD technology in the development of new passenger aircraft, such as the Boeing 787, directly using three-dimensional annotated models as the manufacturing basis, achieving great success in the application of digital technology. Therefore, to advance the implementation and technological level of digital design and manufacturing in the domestic manufacturing industry and achieve digital representation of inspection information, it is necessary to conduct research on three-dimensional digitalization technologies suitable for the development of my country's manufacturing industry, combining current aircraft digital manufacturing processes. The establishment of MBD-based three-dimensional inspection digital models is a prerequisite for the application of digital inspection technology, and the intelligent creation of three-dimensional dimensioning information is a key step. Although the 3D modeling software CATIA includes a 3D annotation module (Functional Tolerancing & Annotation), its functionality is limited, the operation process is cumbersome, and it cannot quickly and completely express dimensioning information. Furthermore, designers often work in an environment that exports 2D engineering drawings, making it difficult to transition from 2D thinking to 3D manual annotation. Therefore, to shorten product development cycles and improve aircraft development quality, it is necessary to develop an automated 3D dimensioning method. Using simple human-computer interaction, this method can automatically annotate 3D dimensions, eliminating the need for 2D engineering drawings and freeing engineers from the tedious 2D drawing production process. Using this automated 3D dimensioning technology, designers can quickly construct 3D inspection models and use them as the sole basis for manufacturing and inspection, truly achieving paperless 3D digital integrated manufacturing. Furthermore, this method significantly reduces workload, unifies the data representation of design and manufacturing information upstream and downstream, and effectively improves the R&D efficiency of designers in the manufacturing industry.

[0003] Traditional inspection methods have the following disadvantages:

[0004] 1. The 3D model needs to be exported to 2D engineering drawings. Deviations or omissions may occur during data conversion, resulting in ambiguity. In addition, the rework rate of 2D drawing design changes is high, resulting in a lot of labor waste.

[0005] 2. Two-dimensional engineering drawing relies entirely on manual annotation, which is arduous and slow to produce, seriously restricting the development efficiency of product parts, and cannot guarantee the integrity and accuracy of the annotation information.

[0006] 3. The traditional process requires continuous projection conversion between three-dimensional and two-dimensional. The expression of three-dimensional structural information is not intuitive and is prone to misunderstanding.

[0007] 4. The 3D annotation module built into CATIA software is complex to operate, has low annotation efficiency, and operators are not familiar enough with it, making it difficult to meet the needs of actual production applications. Summary of the Invention

[0008] The purpose of the present invention is to solve the technical problems existing in the prior art and provide a method for automatically generating three-dimensional part dimensioning based on MBD.

[0009] To achieve the above purpose, the present invention provides a technical solution: a method for automatically generating 3D part dimensioning based on MBD, characterized in that: the method includes:

[0010] Step 1: Obtain the annotation document in the parts product;

[0011] Step 2: Get the TPS object set list and retrieve the annotation set in the file in the form of a TPS object list; if successful, use it as the storage location for subsequent dimension annotation information; if unsuccessful, create a new annotation set;

[0012] Step 3: Build a general path and initialize the TTRS (Technologically and Topologically Related Surface) factory. TTRS is a surface related to process and topology.

[0013] Step 4: Manage annotation views and obtain the list of annotation views in the annotation set through the TPS object set interface. If no annotation view set exists, create a new annotation view set as the carrier of the annotation information.

[0014] Step 5: Perform a topological object structure analysis on the geometric body of the 3D model, extract all the boundary elements contained in the geometric body, and perform judgment and filtering to obtain a unique set of boundary annotation elements;

[0015] Step 6: traverse the annotation element set, classify the annotation elements into plane elements and surface elements, obtain the surface type of the annotation elements, and extract the annotation elements that conform to the circular surface;

[0016] Step 7: Traverse the surface annotation element set, obtain the upper and lower limit points of the geometric surface, and extract its parameter values ​​in the U and V directions. At the same time, classify and label different surface element types;

[0017] Step 8: For the plane element type, complete the selection of the annotation element through manual interaction, then analyze its topology and geometric structure to complete the automatic annotation of the plane element's shape and size;

[0018] Step 9: For annotation view management, when creating an annotation view, the normal vector of the annotation view to be created must be compared with the normal vectors of the existing annotation views in the annotation set. If a parallel or overlapping annotation view exists, the existing view is used as the supporting view for the dimensioning. If not, a new annotation view is created to facilitate information management and identification.

[0019] Step 10: Update the 3D digital model of the product parts and display all dimension annotation information in the annotation set in the 3D model and the structure tree.

[0020] Preferably, step 1 specifically includes the following steps:

[0021] Step 101: Get the current document pointer of the file by obtaining the current document editor object;

[0022] Step 102: Implement an interface through a file containing tolerance information, allowing access to the tolerance set in the file and obtaining a pointer to the annotation document.

[0023] Preferably, step 3 specifically includes the following steps:

[0024] Step 301: extract the current pointer active object, access the structure tree information of the part product file, obtain the part geometry in the product file, set the current active object, and use it to build a universal path;

[0025] Step 302: Screen and extract annotation elements, and perform object characterization operations on them;

[0026] Step 303: Create a TTRS factory object and initialize the TTRS factory;

[0027] Step 304: construct a global variable set for storing the failed face markings, and pre-set a dialog box display list and highlighting operation for the elements in the set.

[0028] Preferably, step 4 specifically includes the following steps:

[0029] Step 401: Obtain the annotation view list in the annotation set through the TPS object set interface. If it does not exist, create a new annotation view set as a carrier of the annotation information.

[0030] Step 402: Create a view factory and construct a annotation plane based on the association between annotation elements and dimensions.

[0031] Step 403: Repeatedly determine the annotation view, comparing the normal vector of the newly constructed annotation plane with the normal vectors of the annotation views in the existing annotation view set to reduce unnecessary view generation;

[0032] Step 404: Before creating the annotation information, set the annotation view that supports the annotation information to an active state.

[0033] Preferably, step 5 specifically includes the following steps:

[0034] Step 501: Access the geometric structure of the part 3D model, extract all edge topology objects, and save them into the total set of edge elements;

[0035] Step 502: traverse all edge elements in the total set, obtain the surface cell structure units directly connected to them, and analyze their topological structures and geometric surfaces;

[0036] Step 503: By calculating, measuring and comparing the center of gravity and area of ​​the surface elements, duplicate surface cell units are screened out and the boundary elements associated with them are deleted to obtain a filtered boundary annotation element set.

[0037] Preferably, step 6 specifically includes the following steps:

[0038] Step 601: traverse the filtered edge element set to obtain the directly connected surface cells, and then obtain the geometric surface of the surface through the surface cells;

[0039] Step 602: Check the two direction parameters of the geometric surface and determine whether it is consistent with the circular contour surface. If it is consistent, add it to the surface annotation element set; if it is not consistent, add it to the annotation failure surface set.

[0040] Preferably, step 7 specifically includes the following steps:

[0041] Step 701: Create a global parameter representing a point on the CATSurface based on the parameter values ​​of the two extreme points, and obtain the direction vector of this point in the U and V directions on the surface;

[0042] Step 702: Obtain mathematical points related to the global parameter point, and create two mutually perpendicular annotation planes Plane(U) and Plane(V) according to the direction vectors in the U and V directions.

[0043] Step 703: If the geometric surface is a cylindrical surface, obtain the high and low angle limits of the cylindrical surface, calculate the curvature of the cylindrical surface, and extract the corresponding annotation elements;

[0044] Step 704: If the curvature of the cylindrical surface is less than 180°, mark it as a fillet, mark the fillet radius and mark the plane as Plane(V); otherwise, mark it as a cylindrical surface, mark the cylindrical surface diameter and mark the plane as Plane(U);

[0045] Step 705: If the geometric surface is a conical surface, extract its related elements, mark its bottom diameter, and mark the plane as Plane(U);

[0046] Step 706: Mark the height limits of the cylindrical surface and the conical surface, obtain the corresponding non-adjacent annotation elements, complete the annotation of the height of the cylinder or cone, and mark the plane as Plane(U);

[0047] Step 707: If the geometric surface is a spherical surface, i.e., a rounded corner, directly mark its spherical diameter and mark the plane as Plane(U);

[0048] Step 708: If it does not belong to any of these surface types or the annotation fails, it is stored in the annotation failure surface set and displayed in the dialog box list.

[0049] Preferably, step 8 specifically includes the following steps:

[0050] Step 801: Construct a selection agent, create a plane annotation command, and associate it with a dialog box control command;

[0051] Step 802: Obtain the plane element selected by the selection agent, analyze its topological structure object, and extract all edges on the plane;

[0052] Step 803: Filter all the edges, delete the curve elements and repeated elements contained in the edge set, and extract the straight edge element set;

[0053] Step 804: Obtain the mathematical plane of the annotation element and set it as a parameter for constructing the annotation view during the plane annotation process;

[0054] Step 805: Perform a parallelism check loop on the straight edge elements, classify and save the mutually parallel straight line elements into different sets, and filter out the individual non-parallel straight line elements. Extract the positions of the two endpoints of the straight line segment and mark the horizontal and vertical distances between the two points.

[0055] Step 806: Traverse the multiple parallel elements in the selected set. For a set of parallel straight line annotations, select the farthest straight line element as the reference, and mark the distance dimensions between the other parallel straight lines and the reference to ensure that the dimensions are not redundant, and complete the annotation of the plane shape dimensions.

[0056] Beneficial effects of the present invention:

[0057] 1. The present invention can analyze the geometric topological structure of the three-dimensional model of the part, extract the relevant annotation elements, and organize, filter and classify them to extract the set of annotation elements that meet the requirements. Finally, according to the program design algorithm, the rapid annotation of the part size information is realized, and some incomplete or irregular surfaces are centrally processed and highlighted.

[0058] 2. The three-dimensional inspection model constructed by the present invention serves as the sole basis for inspection work, realizing a true single data source. It not only ensures the accuracy and integrity of inspection planning information data, but also forms an integrated closed-loop control of design-manufacturing-testing in the product development process, reducing the preparation time of part design, cutting costs, and improving engineering quality.

[0059] 3. The present invention directly performs 3D annotation on the 3D model, and the detection information is directly expressed on the 3D model, and no 2D drawings are output. This can ensure the unification of data sources, reduce unnecessary manpower and a large amount of repetitive work, and reduce the rework rate of products. The digital transmission of MBD-based data avoids the conversion process between model data and detection data, improves detection efficiency and quality, and shortens the product development cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0061] Figure 1 This is a flowchart for automatically generating dimension annotations for three-dimensional parts based on MBD in the present invention. DETAILED DESCRIPTION

[0062] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0063] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0064] To overcome the problems of cumbersome 2D drawing export, slow inspection speed, high cost, and easy operation errors in the traditional inspection method during part inspection, a method for automatically generating 3D part dimension annotation based on MBD is proposed. This invention provides an auxiliary work for 3D annotation for digital inspection technology to meet the current production level of the manufacturing industry, improve the efficiency and quality of part inspection, reduce unnecessary manpower and labor waste, and reduce production costs. The method first performs structural analysis on the topological objects of the geometric body, extracts all boundary elements on the geometric body, and traverses each boundary element in the set to analyze its related topological structure and geometric surface. After screening, filtering and classification, a set of annotation elements of various types is obtained. Secondly, for different types of annotation elements, the qualitative positioning association between annotation elements and dimensions is analyzed, and corresponding dimension annotation algorithms are designed. Then, annotation planes are created according to the requirements of dimension generation and repeated judgment is performed with existing annotation view sets to reduce the generation of unnecessary views. Finally, dimension information is quickly generated, and the generated annotation information is checked for redundancy, removing redundant dimensions, and realizing the construction of a 3D inspection model.

[0065] The present invention can help designers quickly and efficiently complete the generation of three-dimensional dimension annotation information for parts, directly express part manufacturing and inspection information on the three-dimensional model, abandoning the traditional tedious operation of exporting two-dimensional drawings and then manually annotating them, thereby improving product development efficiency and shortening the production cycle.

[0066] Example 1

[0067] Reference Figure 1 A preferred embodiment of the present invention provides a method for automatically generating 3D part dimensioning based on MBD, the method comprising the following steps:

[0068] Step 1: Get the current document pointer of the file by obtaining the current document editor object, and then obtain the annotation document in the part product through the tolerance document interface.

[0069] Step 2: Construct the dimension information carrier. Access the relevant TPS document and retrieve the dimension set in the file in the format of TPS object list. If it does not exist, create a new dimension set as the storage location for the subsequent dimension information.

[0070] Step 3: Build a general path and initialize the TTRS (Technologically and Topologically Related Surface) factory. TTRS is a surface related to process and topology.

[0071] Specifically, step 301 extracts the current pointer active object, accesses the structure tree information of the part product file, obtains the part geometry in the product file, sets the current active object, and uses it to construct the general path;

[0072] Step 302: Screen and extract annotation elements, and perform object characterization operations on them;

[0073] Step 303: Create a TTRS factory object and initialize the TTRS factory;

[0074] Step 304: construct a global variable set for storing the failed face markings, and pre-set a dialog box display list and highlighting operation for the elements in the set.

[0075] Step 4: Manage annotation views, create annotation view sets, and create annotation planes.

[0076] Specifically, in step 401 , the annotation view list in the annotation set is obtained through the TPS object set interface. If the list does not exist, a new annotation view set is created as a carrier of the annotation information.

[0077] Step 402: Create a view factory and construct a annotation plane based on the association relationship between annotation elements and dimensions.

[0078] Step 403 : Repeatedly judge the annotation view, compare the normal vector of the newly constructed annotation plane with the normal vectors of the annotation views in the existing annotation view set, and reduce the generation of unnecessary views.

[0079] Step 404: Before creating the annotation information, set the annotation view that supports the annotation information to an active state.

[0080] Step 5: Geometric topological object analysis: Extract all boundary elements contained in the geometric body and perform judgment and filtering to obtain a unique set of boundary annotation elements.

[0081] Specifically, in step 501 , the geometric structure of the three-dimensional model of the part is accessed, all edge topological objects are extracted, and saved into the total set of edge elements.

[0082] Step 502: traverse all edge elements in the total set, obtain the surface cell structure units directly connected to them, and analyze their topological structures and geometric surfaces.

[0083] Step 503: By calculating, measuring and comparing the center of gravity and area of ​​the surface elements, duplicate surface cell units are screened out and the boundary elements associated with them are deleted to obtain a filtered boundary annotation element set.

[0084] Step 6: Traverse the annotation element set and classify the annotation elements into plane elements and surface elements. Develop corresponding dimensioning methods for different element types.

[0085] Step 7: For the surface element type, extract its corresponding geometric surface, obtain its upper and lower limit points, and determine whether its surface type is cylindrical, conical, filleted, spherical, etc., and then add it to the corresponding annotation set. Complete the annotation of the surface type element according to the relevant annotation algorithm designed by the program

[0086] Step 8: For planar elements, select the annotation elements through manual interaction. Then, analyze their topology and geometry to extract a set of linear boundary annotation elements. Then, perform a parallel loop check on the annotation elements within this set. Finally, for multiple parallel linear elements, select a reference and annotate their relative positions. For individual non-parallel linear elements, directly annotate the horizontal and vertical distances between their endpoints.

[0087] Step 9: Perform redundancy check on all dimensions in the annotation set, traverse each annotation information, and analyze its TTRS object. If there are duplicate elements, delete the relevant duplicate annotation information.

[0088] Step 10: Update the 3D digital model of the product parts and display all dimension annotation information in the annotation set in the 3D model and the structure tree.

[0089] The present invention can analyze the geometric topological structure of the three-dimensional model of the part, extract the relevant annotation elements, and organize, filter and classify them to extract a set of annotation elements that meets the requirements. Finally, according to the program design algorithm, the rapid annotation of the part size information is realized, and some incomplete or irregular surfaces are centrally processed and highlighted.

[0090] The three-dimensional inspection model constructed by the present invention serves as the sole basis for inspection work, realizing a true single data source. It not only ensures the correctness and integrity of the inspection planning information data, but also forms an integrated closed-loop control of design-manufacturing-testing in the product development process, reducing the preparation time of part design, cutting costs, and improving engineering quality.

[0091] The present invention directly performs three-dimensional annotation on the three-dimensional model, and expresses the detection information directly on the three-dimensional model, and no longer outputs two-dimensional drawings. This can ensure the unification of data sources, reduce unnecessary manpower and a large amount of repetitive work, and lower the rework rate of products. The digital transmission of MBD-based data avoids the conversion process between model data and detection data, improves detection efficiency and quality, and shortens the product development cycle.

[0092] In summary, the present invention can help designers quickly and efficiently complete the generation of three-dimensional dimension annotation information for parts, directly express part manufacturing and inspection information on the three-dimensional model, abandon the traditional tedious operation of exporting two-dimensional drawings and then manually annotating them, thereby improving product development efficiency and shortening the production cycle.

[0093] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0094] The above descriptions are only preferred embodiments of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means shall fall within the scope of protection of the present invention.

Claims

1. A method for automatically generating 3D part dimensioning based on MBD, characterized by: The method comprises the following steps: Step 1: Obtain the annotation document in the parts product; Step 2: Get the TPS object set list and retrieve the annotation set in the file in the form of a TPS object list; if successful, use it as the storage location for subsequent dimension annotation information; if unsuccessful, create a new annotation set; Step 3: Build a general path and initialize the TTRS factory, where TTRS is a surface related to process and topology; Step 4: Manage annotation views and obtain the list of annotation views in the annotation set through the TPS object set interface. If no annotation view set exists, create a new annotation view set as the carrier of the annotation information. Step 5: Perform a topological object structure analysis on the geometric body of the 3D model, extract all the boundary elements contained in the geometric body, and perform judgment and filtering to obtain a unique set of boundary annotation elements; Step 6: traverse the annotation element set, classify the annotation elements into plane elements and surface elements, obtain the surface type of the annotation elements, and extract the annotation elements that conform to the circular surface; Step 7: Traverse the surface annotation element set, obtain the upper and lower limit points of the geometric surface, and extract its parameter values ​​in the U and V directions. At the same time, classify and label different surface element types; Step 8: For the plane element type, complete the selection of the annotation element through manual interaction, then analyze its topology and geometric structure to complete the automatic annotation of the plane element's shape and size; Step 9: For annotation view management, when creating an annotation view, the normal vector of the annotation view to be created must be compared with the normal vectors of the existing annotation views in the annotation set. If a parallel or overlapping annotation view exists, the existing view is used as the supporting view for the dimensioning. If not, a new annotation view is created to facilitate information management and identification. Step 10: Update the 3D digital model of the product parts and display all dimension annotation information in the annotation set in the 3D model and the structure tree.

2. The method for automatically generating 3D part dimensioning based on MBD according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step 101: Get the current document pointer of the file by obtaining the current document editor object; Step 102: Implement an interface through a file containing tolerance information, allowing access to the tolerance set in the file and obtaining a pointer to the annotation document.

3. The method for automatically generating 3D part dimensioning based on MBD according to claim 1, characterized in that: Step 3 specifically includes the following steps: Step 301: extract the current pointer active object, access the structure tree information of the part product file, obtain the part geometry in the product file, set the current active object, and use it to build a universal path; Step 302: Screen and extract annotation elements, and perform object characterization operations on them; Step 303: Create a TTRS factory object and initialize the TTRS factory; Step 304: construct a global variable set for storing the failed face markings, and pre-set a dialog box display list and highlighting operation for the elements in the set.

4. The method for automatically generating 3D part dimensioning based on MBD according to claim 1, characterized in that: Step 4 specifically includes the following steps: Step 401: Obtain the annotation view list in the annotation set through the TPS object set interface. If it does not exist, create a new annotation view set as a carrier of the annotation information. Step 402: Create a view factory and construct a annotation plane based on the association between annotation elements and dimensions. Step 403: Repeatedly determine the annotation view, comparing the normal vector of the newly constructed annotation plane with the normal vectors of the annotation views in the existing annotation view set to reduce unnecessary view generation; Step 404: Before creating the annotation information, set the annotation view that supports the annotation information to an active state.

5. The method for automatically generating 3D part dimensioning based on MBD according to claim 1, characterized in that: Step 5 specifically includes the following steps: Step 501: Access the geometric structure of the part 3D model, extract all edge topology objects, and save them into the total set of edge elements; Step 502: traverse all edge elements in the total set, obtain the surface cell structure units directly connected to them, and analyze their topological structures and geometric surfaces; Step 503: By calculating, measuring and comparing the center of gravity and area of ​​the surface elements, duplicate surface cell units are screened out and the boundary elements associated with them are deleted to obtain a filtered boundary annotation element set.

6. The method for automatically generating 3D part dimensioning based on MBD according to claim 1, characterized in that: Step 6 specifically includes the following steps: Step 601: traverse the filtered edge element set to obtain the directly connected surface cells, and then obtain the geometric surface of the surface through the surface cells; Step 602: Check the two direction parameters of the geometric surface and determine whether it conforms to the circular contour surface; if it conforms, add it to the surface annotation element set; if it does not conform, add it to the annotation failure surface set.

7. The method for automatically generating 3D part dimensioning based on MBD according to claim 1, characterized in that: Step 7 specifically includes the following steps: Step 701: Create a global parameter representing a point on the CATSurface based on the parameter values ​​of the two extreme points, and obtain the direction vector of this point in the U and V directions on the surface; Step 702: Obtain mathematical points related to the global parameter point, and create two mutually perpendicular annotation planes Plane(U) and Plane(V) according to the direction vectors in the U and V directions. Step 703: If the geometric surface is a cylindrical surface, obtain the high and low angle limits of the cylindrical surface, calculate the curvature of the cylindrical surface, and extract the corresponding annotation elements; Step 704: If the curvature of the cylindrical surface is less than 180°, mark it as a fillet, mark the fillet radius and mark the plane as Plane(V); otherwise, mark it as a cylindrical surface, mark the cylindrical surface diameter and mark the plane as Plane(U); Step 705: If the geometric surface is a conical surface, extract its related elements, mark its bottom diameter, and mark the plane as Plane(U); Step 706: Mark the height limits of the cylindrical surface and the conical surface, obtain the corresponding non-adjacent annotation elements, complete the annotation of the height of the cylinder or cone, and mark the plane as Plane(U); Step 707: If the geometric surface is a spherical surface, i.e., a rounded corner, directly mark its spherical diameter and mark the plane as Plane(U); Step 708: If it does not belong to any of these surface types or the annotation fails, it is stored in the annotation failure surface set and displayed in the dialog box list.

8. The method for automatically generating 3D part dimensioning based on MBD according to claim 1, characterized in that: Step 8 specifically includes the following steps: Step 801: Construct a selection agent, create a plane annotation command, and associate it with a dialog box control command; Step 802: Obtain the plane element selected by the selection agent, analyze its topological structure object, and extract all edges on the plane; Step 803: Filter all the edges, delete the curve elements and repeated elements contained in the edge set, and extract the straight edge element set; Step 804: Obtain the mathematical plane of the annotation element and set it as a parameter for constructing the annotation view during the plane annotation process; Step 805: Perform a parallelism check loop on the straight edge elements, classify and save the mutually parallel straight line elements into different sets, and filter out the individual non-parallel straight line elements. Extract the positions of the two endpoints of the straight line segment and mark the horizontal and vertical distances between the two points. Step 806: Traverse the multiple parallel elements in the selected set. For a set of parallel straight line annotations, select the farthest straight line element as the reference, and mark the distance dimensions between the other parallel straight lines and the reference to ensure that the dimensions are not redundant, and complete the annotation of the plane shape dimensions.

Images