Aircraft sheet metal part model rapid identification method based on thickness dimension characteristics

Abstract

The invention relates to the technical field of aeronautical manufacturing, and discloses an airplane sheet metal part model rapid identification method based on thickness dimension characteristics, which comprises the following steps: analyzing, processing and converting given part model data, discretizing the geometric surface of a part, extracting or calculating the thickness dimension characteristics of points on each surface, and calculating the thickness dimension characteristics of the points on each surface; and sheet metal part model identification is realized by checking the consistency of the comprehensive thickness size and the reference thickness size of the part. According to the method, the sheet metal part model can be efficiently and accurately screened from the aircraft design model, the problems that a current manual screening mode is large in workload, low in efficiency, prone to making mistakes and the like are solved, the production preparation period of aircraft manufacturing process division and related links is shortened, and more accurate input is provided for sheet metal part process design; meanwhile, a calculation method for the comprehensive thickness size and the fillet thickness size is provided, the accuracy is guaranteed, meanwhile, it is effectively avoided that a large amount of thickness size feature calculation is conducted on the model, and the calculation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft manufacturing, and specifically, to a method for quickly identifying aircraft sheet metal part models based on thickness dimension features. Background Art

[0002] Sheet metal parts are widely used in aircraft product structures due to their characteristics such as light weight, high strength, low cost, and easy production. According to statistics, in the overall aircraft structure, the proportion of sheet metal parts can reach up to 50%. Sheet metal process design is the key link determining the production quality and efficiency of sheet metal parts, and the prerequisite is to issue the correct part design model to sheet metal process designers. However, aircraft design models are usually organized according to product functions or structures, rather than classified and organized according to part types. This organization method of design models is inconsistent with the current production division and organization mode of aircraft professional factories (such as sheet metal factories, machining factories, and composite material factories), resulting in that aircraft design models must be classified, screened, and issued to the corresponding professional factories before subsequent part process design and production manufacturing can be carried out. Moreover, the large number of aircraft sheet metal part models, their complex and diverse geometric shapes, and their similarity to other types of part models pose great challenges to how to accurately and efficiently identify them.

[0003] In view of the above problems, aviation manufacturing enterprises currently mainly use manual screening methods to identify sheet metal part models, which have the disadvantages of large workload, low efficiency, and easy misjudgment. From the analysis of the research status at home and abroad, the methods proposed in some literature have certain reference value for the identification of aircraft sheet metal part models, but at present, there are no reported mature technical solutions and methods that can directly solve the rapid identification of aircraft sheet metal part models. For example, in the patent "An Automatic Recognition Method for Sheet Metal Part Surface Difference Surfaces Based on UG NX Secondary Development (Authorization Publication Number: CN113688476B, Authorization Publication Date: November 23, 2021)", all surface difference surfaces can be automatically recognized on sheet metal parts; in the patent "A Part Processing Feature Recognition Method Based on Machine Vision Learning Recognition (Authorization Publication Number: CN114067231B, Authorization Publication Date: May 10, 2022)", machine learning methods are used to solve the recognition of complex processing features and new processing features; in the patent "An Automatic Recognition and Positioning Method for Sheet Metal Parts Based on DXF (Authorization Publication Number: CN113111458B, Authorization Publication Date: October 21, 2022)", irregular sheet metal graphics on metal plates can be recognized and positioned, mainly applicable to two-dimensional sheet parts processed by laser cutting; in the patent "Revolving Machining Feature Recognition Method and Device (Authorization Publication Number: CN110837694B, Authorization Publication Date: October 20, 2023)", revolving parts and revolving machining features can be recognized. The focus of the above invention patents is to solve the problem of part processing feature recognition, focusing on recognizing local processing features with certain engineering semantics from a given part model, rather than identifying and classifying part types. Summary of the Invention

[0004] The purpose of the present invention is to provide a rapid identification method for aircraft sheet metal part models based on thickness dimension features, so as to solve the problems of large workload, low efficiency, and easy misjudgment existing in the identification of sheet metal part models by manual screening methods.

[0005] The present invention is achieved through the following technical solutions: A rapid identification method for aircraft sheet metal part models based on thickness dimension features realizes the identification of sheet metal part models by checking the consistency between the comprehensive thickness dimension of the part and the reference thickness dimension. The specific steps include: Step S1: Batch read the part models to be identified according to the folder path set by the user , where , represents the part model serial number, represents the total number of part models, set , and set two sets with initial values being empty and , which are used to record non-sheet metal part models and sheet metal part models respectively; Step S2: If , calculate the reference thickness dimension of the part model ; otherwise, execute step S9; Step S3. For the part model to be recognized , calculate the comprehensive thickness dimension of the part model ; Step S4. Check the consistency between the comprehensive thickness dimension and the reference thickness dimension. If the consistency requirement is not met, it is determined that the part model is a non-sheet metal part. At this time, add to the non-sheet metal part model set , and then set , and return to step S2; Step S5. Traverse the fillet features in the part model , , represents the serial number of the fillet feature, represents the total number of fillet features; if , go to step S8, otherwise set ; Step S6. When , calculate the thickness dimension of the fillet feature ; otherwise, execute step S8; Step S7. Check the consistency between the fillet thickness dimension and the reference thickness dimension. If the consistency is not met, it is determined that the part model is a non-sheet metal part. At this time, add to the non-sheet metal part model set , and set , go to step S2, otherwise set , and return to step S6; Step S8. Determine that the part model is a sheet metal part, add to the sheet metal part model set , and set , go to step S2; Step S9. Output all the models in the non-sheet metal part model set and the sheet metal part model set respectively.

[0006] To better implement the present invention, further, the calculation steps of the reference thickness dimension in step S2 are as follows: Step S21. Traverse the geometric surfaces in the part model ​, , represents the serial number of the geometric surface, and represents the total number of geometric surfaces; Step S22: Starting from , calculate the area of each geometric surface in a loop until the loop ends. Then, by comparing the obtained area values, find the geometric surface with the largest area ; ; Step S23: Discretize the geometric surface according to the set precision to obtain a number of geometric points , , where represents the serial number of the geometric point, and represents the total number of geometric points; Step S24: Starting from , calculate the shortest distance from the geometric point to the boundary of the geometric surface in a loop until the loop ends. Then, by comparing the obtained shortest distance values, find the geometric point that satisfies the shortest distance value ; Step S25: Obtain the normal vector of the geometric point on the geometric surface , and the positive direction of this normal vector points to the inside of the three-dimensional solid of the part model; Step S26: Starting from , calculate the projection distance from the geometric point to the geometric surface in a loop, and the projection direction is the normal vector until the loop ends. Then, from all the projection distance values, find the non-zero and minimum projection distance value, and this distance value is the reference thickness dimension .

[0007] To better implement the present invention, further, the calculation steps of the comprehensive thickness dimension in step S3 are as follows: Step S31: Using the geometric surface area calculated in step 2.2, further calculate the surface area of the part model, and the calculation expression is: ; Step S32: Determine whether the geometric surface contains the reference thickness dimension feature; Step S33: If the geometric surface If it contains the reference thickness dimension feature, update the surface area The expression of is: Step S34: Repeat steps S32 to S33 until all geometric surfaces have been judged, and the final surface area is obtained; Step S35: Calculate the volume of the part model , and according to and , calculate the comprehensive thickness dimension of the part model ; The calculation formula is: .

[0008] To better implement the present invention, further, the judgment rule for whether the geometric surface in step S32 contains the reference thickness dimension feature is: Obtain all the boundary lines of the geometric surface , measure the shortest distance between any two boundary lines respectively. If the shortest distance between two boundary lines is equal to the reference thickness dimension , then contains the reference thickness dimension feature; otherwise, does not contain the reference thickness dimension feature.

[0009] To better implement the present invention, further, the calculation method of the thickness dimension in step S6 is as follows: Step S61: Obtain a geometric point on the fillet feature and the normal vector pointing to the inside of the three-dimensional entity at this point; Step S62: Starting from , loop to calculate the projection distance of the geometric point to the geometric surface , and the projection direction is the normal vector , until ends the loop. Then, from all the projection distance values, find the non-zero and minimum projection distance value, and this distance value is the thickness dimension of the fillet feature .

[0010] To better implement the present invention, further, when checking the consistency between the comprehensive thickness dimension and the reference thickness dimension , if , it is determined that the consistency requirement is not met; when checking the thickness dimension of the fillet feature ​ Consistency with the reference thickness dimension When checking the consistency with the reference thickness dimension, if , it is determined that the consistency requirement is not met; where is the precision parameter for consistency check.

[0011] To better implement the present invention, further, the .

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention utilizes a significant difference between sheet metal parts and other types of parts: the thickness dimensions at any point on the surface of sheet metal parts are equal. A method for quickly identifying sheet metal part models is proposed. By parsing, processing, and converting the given part model data, the discrete point set of the part geometric surface is obtained, the thickness dimension features of the points on each surface are extracted or calculated, and by judging whether the thickness dimensions of the part are equal, the sheet metal part models are efficiently and accurately screened out from the aircraft design model, solving the problems of large workload, low efficiency, and easy errors existing in the current manual screening method. It can shorten the production preparation cycle of aircraft manufacturing process division and related links, and can also provide more accurate input for the process design of sheet metal parts; (2) The present invention calculates a reliable reference thickness dimension on the part model as a benchmark, and realizes the identification of sheet metal part models by checking the consistency between other thickness dimensions and the reference thickness dimension, which can give accurate quantitative information and also reflect the specific parts on the part model that do not meet the equal-thickness characteristics of sheet metal parts; (3) The present invention proposes a calculation method for comprehensive thickness dimension and fillet thickness dimension, which can quickly judge whether the part model is a sheet metal part as a whole, and at the same time can consider the local features and dimensions on the part model. Therefore, while ensuring accuracy, it effectively avoids a large number of thickness dimension feature calculations on the model and improves the calculation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is an example of the part to be tested in the specific embodiment of the present invention. SPECIFIC EMBODIMENT

[0014] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0015] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can also be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0016] Embodiment 1: This embodiment provides a method for quickly identifying an aircraft sheet metal part model based on thickness dimension features. The sheet metal part model identification is realized by checking the consistency between the comprehensive thickness dimension of the part and the reference thickness dimension. The specific steps include: Step S1: According to the folder path set by the user, batch-read the part models to be identified , where , represents the part model serial number, represents the total number of part models, set , and set two sets with initial values being empty and , which are respectively used to record non-sheet metal part models and sheet metal part models; Step S2: If , then calculate the reference thickness dimension of the part model ; otherwise, execute step S9; Step S3: For the part model to be identified, calculate the comprehensive thickness dimension of this part model; Step S4: Check the consistency between the comprehensive thickness dimension and the reference thickness dimension. If the consistency requirement is not met, it is determined that the part model is a non-sheet metal part. At this time, add to the non-sheet metal part model set , and then set , and return to step S2; Step S5: Traverse the fillet features in the part model , , represents the serial number of the fillet feature, represents the total number of fillet features; if , then go to step S8, otherwise set ; Step S6: When , calculate the thickness dimension of the fillet feature ​ ; Otherwise, execute step S8; Step S7. Check the consistency between the fillet thickness dimension and the reference thickness dimension. If the consistency is not met, it is determined that the part model is a non-sheet metal part. At this time, is added to the non-sheet metal part model set , and is set, then go to step S2. Otherwise, set , and return to step S6; Step S8. Determine that the part model is a sheet metal part. is added to the sheet metal part model set , and is set, then go to step S2; Step S9. Output all the models in the non-sheet metal part model set and the sheet metal part model set respectively.

[0017] Embodiment 2: This embodiment is further extended based on Embodiment 1. The calculation steps of the reference thickness dimension in step S2 are as follows: Step S21. Traverse the geometric surfaces in the part model , , , where represents the geometric surface serial number, and represents the total number of geometric surfaces; Step S22. Starting from , calculate the area of each geometric surface in a loop until the loop ends. Then, by comparing the obtained area values, find the geometric surface with the largest area; Step S23. Discretize the geometric surface , , to obtain a number of geometric points , where represents the geometric point serial number, and represents the total number of geometric points; Step S24. Starting from , calculate the shortest distance from the geometric point to the boundary of the geometric surface in a loop until Step S25: Obtain geometric points On the geometric surface The normal vector whose positive direction points to the inside of the three-dimensional solid of the part model; Step S26: Starting from calculate the projection distance of the geometric point towards the geometric surface in a loop, and the projection direction is the normal vector until the loop ends. Then, from all the projection distance values, find the non-zero and minimum projection distance value, and this distance value is the reference thickness dimension .

[0018] The calculation steps of the comprehensive thickness dimension described in step S3 are as follows: Step S31: Using the geometric surface area calculated in step 2.2, further calculate the surface area of the part model, and the calculation expression is: ; Step S32: Determine whether the geometric surface contains the reference thickness dimension feature; Step S33: If the geometric surface contains the reference thickness dimension feature, update the surface area , and the update expression is: ; Step S34: Repeat steps S32 to S33 until all geometric surfaces have completed the judgment to obtain the final surface area ; Step S35: Calculate the volume of the part model , and based on and , calculate the comprehensive thickness dimension of the part model ; the calculation formula is: .

[0019] The judgment rule for whether the geometric surface in step S32 contains the reference thickness dimension feature is: Obtain all the boundary lines of the geometric surface , measure the shortest distance between any two boundary lines respectively. If there is a shortest distance between two boundary lines that is equal to the reference thickness dimension , then it contains the reference thickness dimension feature; otherwise, it does not contain the reference thickness dimension feature.

[0020] The thickness dimension in step S6 is calculated as follows: Step S61. Obtain a geometric point on the fillet feature and the normal vector pointing to the inside of the 3D solid at this point ; Step S62. Starting from , loop to calculate the projection distance of the geometric point onto the geometric plane , with the projection direction being the normal vector , until the loop ends. Then, from all the projection distance values, find the non-zero and minimum projection distance value, and this distance value is the thickness dimension of the fillet feature . .

[0021] Set the precision parameter for consistency check . When checking the consistency between the comprehensive thickness dimension and the reference thickness dimension, if , it is determined that the consistency requirement is not met; when checking the consistency between the fillet thickness dimension and the reference thickness dimension, if , it is determined that the consistency requirement is not met. Preferably, .

[0022] Based on the above steps 1 - 9, this embodiment develops a computer program, using the 8 representative part models to be recognized shown in Figure 1 as the input to verify the technical solution of the present invention. After repeated manual identification, Figure 1 parts 1 - 4 are sheet metal parts, and parts 5 - 8 are non-sheet metal parts. This identification result is used as the comparison basis for the program calculation result; from an overall perspective, the present invention accurately identifies all sheet metal part models from the 8 part models to be recognized, with an accuracy rate of 100%.

[0023] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention falls within the protection scope of the present invention.

Claims

1. A method for rapid identification of aircraft sheet metal parts models based on thickness dimension features, characterized in that: The sheet metal part model is identified by checking the consistency between the comprehensive thickness dimension of the part and the reference thickness dimension. The specific steps include: Step S1: Batch read the part models to be identified according to the folder path set by the user ,in , Indicates the part model number, Indicates the total number of part models, set , set two sets with initial values ​​​​to be empty and , used to record non-sheet metal part models and sheet metal part models respectively; Step S2: If , then calculate the part model Reference thickness dimensions ; Otherwise, execute step S9; Step S3: for the part model to be identified , calculate the comprehensive thickness dimension of the part model ; Step S4: Check the consistency between the comprehensive thickness dimension and the reference thickness dimension. If the consistency requirement is not met, determine the part model. If it is a non-sheet metal part, Add to non-sheet metal part model collection Then set , return to step S2; Step S5: traverse the part model Round feature in , , Indicates the serial number of the round feature. Represents the total number of round features; if , then go to step S8, otherwise set ; Step S6: , calculate the fillet feature Thickness ; Otherwise, execute step S8; Step S7: Check the consistency between the fillet thickness and the reference thickness. If the consistency is not met, determine the part model. It is a non-sheet metal part. Add to non-sheet metal part model collection and set , go to step S2, otherwise set , return to step S6; Step S8: Determine the part model For sheet metal parts, Add to Sheet Metal Part Model Collection and set , go to step S2; Step S9: Output non-sheet metal part model sets separately and sheet metal part model collection All models in .

2. The method for rapid identification of aircraft sheet metal parts models based on thickness dimension features according to claim 1 is characterized in that: The reference thickness dimension in step S2 The calculation steps are as follows: Step S21, traverse the part model The geometric surface in , , Indicates the geometric surface number, Indicates the total number of geometric faces; Step S22: Start by looping and calculating each geometric surface Area , until End the loop, and then find the geometric surface with the largest area by comparing the obtained area values ; Step S23: Geometric surface Discretize according to the set accuracy to obtain several geometric points , , Indicates the sequence number of the geometric point, Represents the total number of geometric points; Step S24: Start by looping and calculating the geometric points To Geometry The shortest distance to the border, up to End the loop, then find the geometric point that satisfies the shortest distance value by comparing the shortest distance value ; Step S25: Get geometric points On the geometric surface Normal vector , the positive direction of the normal vector points to the interior of the three-dimensional entity of the part model; Step S26: Start by looping and calculating the geometric points Towards geometry The projection distance, the projection direction is the normal vector , until End the loop, and then find the smallest non-zero projection distance value from all projection distance values. This distance value is the reference thickness dimension. .

3. The method for rapid identification of aircraft sheet metal parts models based on thickness dimension features according to claim 2 is characterized in that: The comprehensive thickness dimension in step S3 The calculation steps are as follows: Step S31: Use the geometric surface area calculated in step 2.2 , further calculate the surface area of ​​the part model , the calculation expression is: ; Step S32: Determine the geometric surface Whether to include reference thickness dimension features; Step S33: If the geometric surface If a reference thickness feature is included, the surface area is updated S The expression is: ; Step S34: Repeat steps S32 to S33 until all geometric surfaces are All judgments are completed to obtain the final surface area ; Step S35: Calculate part model Volume , and according to and , calculate the part model Comprehensive thickness dimension ; The calculation formula is: .

4. The method for rapid identification of aircraft sheet metal parts models based on thickness dimension features according to claim 3 is characterized in that: The geometric surface in step S32 The judgment rule of whether to include reference thickness dimension feature is as follows: Get the geometric surface For all boundary lines, measure the shortest distance between any two boundary lines respectively. If there is a shortest distance between two boundary lines that is equal to the reference thickness dimension If they are equal, Include reference thickness size features, otherwise, Reference thickness size features are not included.

5. The method for rapid identification of aircraft sheet metal parts models based on thickness dimension features according to claim 3 is characterized in that: The thickness dimension in step S6 The calculation method is as follows: Step S61: rounding feature Get a geometric point on And the normal vector pointing to the interior of the three-dimensional solid at that point ; Step S62: Start by looping and calculating the geometric points Towards geometry The projection distance, the projection direction is the normal vector , until End the loop, and then find the smallest non-zero projection distance value from all projection distance values. This distance value is the rounded corner feature. Thickness .

6. A method for rapid identification of aircraft sheet metal parts models based on thickness dimension features according to any one of claims 1 to 5, characterized in that: When checking the comprehensive thickness dimension h 1 and reference thickness dimensions h 0 consistency, if , it is judged as not meeting the consistency requirements; when checking the rounded corner features C q Thickness γ q With reference thickness dimension h 0 consistency, if , it is judged that the consistency requirement is not met; among them, is the precision parameter used for consistency checking.

7. The method for rapid identification of aircraft sheet metal parts models based on thickness dimension features according to claim 6 is characterized in that: Said .

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