Part assembly tolerance sensitivity identification method and system

Abstract

The present application relates to a kind of part assembly tolerance sensitivity identification method and system, obtain assembly dimension chain and assembly sequence according to the three-dimensional process design model of assembly, obtain the assembly process model corresponding to each process in assembly sequence;For each assembly process model, obtain the position coordinates of the newly assembled plate parts under the process relative to the assembly reference, the distance size of plate parts along the direction of assembly dimension chain, the quantity of embedded parts of the process, the quantity of assembly joint surface and the dimensional tolerance of plate parts, with the position coordinates, distance size, embedded part quantity and plate parts constitute the unit sample of the process;Unit sample of all processes is sequentially constituted into sample set matrix and standardized;Design the assembly tolerance sensitivity evaluation function based on TOPSIS algorithm, evaluate the matrix after standardization, obtain the sensitivity score of each plate part, so that the influence degree of each plate part assembly tolerance on overall assembly accuracy is quickly and accurately obtained.

Description

Technical Field

[0001] This invention relates to the field of computer-aided assembly process design technology, and in particular to a method and system for identifying the sensitivity of assembly tolerances of parts. Background Technology

[0002] Assembly is the most crucial and time-consuming stage in the entire product manufacturing lifecycle, and it is also the final step in achieving the product's overall performance. The development of assembly technology is one of the decisive factors in ensuring product quality and improving production efficiency. To guarantee the reliability and stability of mechanical systems during operation, it is not only necessary to strictly ensure the good design performance and manufacturing quality of components during product design and manufacturing, but more importantly, to ensure the compatibility and fit between components during assembly.

[0003] Identifying the critical dimensions of each part constituting an assembly, and determining which one or more critical dimensions (key assembly dimensions) have the greatest impact on fit performance and thus the overall assembly effect—that is, analyzing the sensitivity of assembly tolerances—is a technical challenge in the assembly process. Current technologies often rely on repeated manual trials combined with experience to address the sensitivity analysis of part assembly tolerances. This method is overly dependent on worker experience, incurs a tedious workload, and is difficult to apply to mass production. Especially in the assembly of sheet metal parts, where a single part simultaneously has multiple constraints such as parallelism, perpendicularity, and position, and often multiple assembly mating surfaces with various coupling relationships, it becomes difficult to scientifically and efficiently identify critical assembly dimensions and provide repair solutions when assembly dimensions exceed tolerances.

[0004] Current computer-aided assembly process design technology also lacks effective technical means to quickly and accurately find key assembly dimensions by analyzing the sensitivity of assembly parts. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and system for identifying the sensitivity of assembly tolerances in parts, with the aim of quickly and accurately identifying the dimensions of key assembly (parts) that affect the assembly performance of an assembly.

[0006] The technical solution adopted in this invention is as follows:

[0007] This invention provides a method for identifying the sensitivity of assembly tolerances of parts, comprising:

[0008] Based on the three-dimensional process design model of the assembly, the assembly dimension chain and assembly sequence are obtained, and the assembly process model corresponding to each process in the assembly sequence is obtained.

[0009] For each assembly process model, obtain the position coordinates of the newly assembled plate-type parts relative to the assembly datum, the distance dimension of the plate-type parts along the assembly dimension chain direction, the number of embedded parts in this process, the number of assembly mating surfaces, and the dimensional tolerance of the plate-type parts. The position coordinates, distance dimension, number of embedded parts, and plate-type parts constitute the unit sample of this process.

[0010] Arrange the unit samples of all processes in order to form a sample set matrix T;

[0011] Standardize the sample set matrix T to obtain the standardized matrix T':

[0012]

[0013] Among them, t' 11 t' 12 t' 13 ...t' 1m The first unit sample is the element after standardization. The subscript m is the number of elements contained in each unit sample, and n is the total number of assembly processes, i.e. the number of plate parts to be assembled.

[0014] Design an assembly tolerance sensitivity evaluation function based on the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) algorithm to evaluate matrix T' and obtain the sensitivity score for each plate-type part:

[0015]

[0016] in, For the i-th plate-type part, the minimum sensitivity evaluation value t - Distance between:

[0017]

[0018] For the i-th plate-type part, the maximum sensitivity evaluation value t + Distance between:

[0019]

[0020] in:

[0021]

[0022]

[0023] Based on the sensitivity score SE for plate-type parts iThe plate-type parts to be assembled are sorted to obtain a ranking of the degree of influence of the assembly tolerance of each plate-type part on the overall assembly accuracy.

[0024] The further technical solution is as follows:

[0025] Obtaining the position coordinates of the newly assembled plate-type parts relative to the assembly datum in this process includes:

[0026] Extract the coordinates of the positions of the axes of the center holes of at least two embedded parts on the main assembly mating surface of the plate-shaped part to be assembled:

[0027] (x1,y1,z1) and (x2,y2,z2), where the subscripts 1 and 2 represent the serial numbers of at least two embedded parts.

[0028] The distance dimension of the plate-type part along the assembly dimension chain direction is characterized by the sum of the distance between the plate-type part to be assembled and the assembly datum and the nominal dimension of the plate-type part in the assembly dimension chain direction.

[0029] After standardization, each element of matrix T' is equal to the value of its corresponding element in the sample set matrix T divided by the square root of the sum of the squares of the elements in its column.

[0030] The method for identifying the sensitivity of assembly tolerance of parts further includes: obtaining a repair scheme based on the ranking of the degree of influence of the assembly tolerance of each plate part on the overall assembly accuracy, and selecting one or more plate parts with a greater degree of influence on the overall assembly accuracy for dimensional repair.

[0031] This application also provides a parts assembly tolerance sensitivity identification system, including:

[0032] Assembly process model acquisition module: Based on the 3D process design model of the assembly, the assembly dimension chain and assembly sequence are obtained, and the assembly process model corresponding to each process in the assembly process is obtained.

[0033] Sample Construction Module: For each assembly process model, obtain the position coordinates of the newly assembled plate-type parts relative to the assembly datum, the distance dimensions of the plate-type parts along the assembly dimension chain direction, the number of embedded parts, the number of assembly mating surfaces, and the dimensional tolerances of the plate-type parts. Use the position coordinates, distance dimensions, number of embedded parts, and plate-type parts to construct the unit sample for that process. Arrange all unit samples sequentially to form a sample set matrix T. Standardize the sample set matrix T to obtain the standardized matrix T'.

[0034]

[0035] Among them, t' 11 t' 12 t' 13 …t1m The first unit sample is the element after standardization. The subscript m is the number of elements contained in each unit sample, and n is the total number of assembly processes, i.e. the number of plate parts to be assembled.

[0036] Sensitivity Evaluation Module: Design an assembly tolerance sensitivity evaluation function based on the TOPSIS algorithm to evaluate matrix T' and obtain the sensitivity score for each plate-type part.

[0037]

[0038] in, For the i-th plate-type part, the minimum sensitivity evaluation value t - Distance between:

[0039]

[0040] For the i-th plate-type part, the maximum sensitivity evaluation value t + Distance between:

[0041]

[0042] in:

[0043]

[0044]

[0045] Based on the sensitivity score SE for plate-type parts i The plate-type parts to be assembled are sorted to obtain a ranking of the degree of influence of the assembly tolerance of each plate-type part on the overall assembly accuracy.

[0046] The beneficial effects of this invention are as follows:

[0047] This application models the assembly tolerance sensitivity attributes of plate-type parts, including three-dimensional coordinates, nominal dimensions, number of embedded parts, contact surfaces, and tolerances, forming multiple sets of sample data. Based on the TOPSIS algorithm, the distance between the evaluation object and the optimal and worst solutions is used to rank the samples, achieving multi-objective decision analysis. The algorithm comprehensively calculates the overall influence factor of each sample on the final assembly tolerance, i.e., sensitivity, and ranks them according to the sensitivity magnitude to obtain the sensitivity of each sample's constituent loop to the final closed loop and the critical assembly dimensions. Adjustments are made based on the identified critical assembly dimensions, thereby improving the assembly efficiency and assembly quality of plate-type parts.

[0048] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0049] Figure 1 This is a flowchart illustrating the method of the present invention. Detailed Implementation

[0050] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0051] See Figure 1 The part assembly tolerance sensitivity identification method of this embodiment includes:

[0052] S1. Import the 3D process design model of the assembly into the 3D CAPP software. Use the 3D CAPP software to parse and obtain the assembly dimension chain and assembly sequence. Based on the 3D assembly sequence, display the assembly process model corresponding to each process in each sequence. The assembly process model refers to the set of 3D assembly process model and corresponding assembly process information under the current process.

[0053] S2. For the first assembly process model, measure the position coordinates of the newly installed plate-type parts relative to the assembly datum, including (x1, y1, z1) and (x2, y2, z2).

[0054] (x1,y1,z1) and (x2,y2,z2) are the position coordinates of the axis of the center hole of the two outermost embedded parts on the main assembly mating surface of the plate-shaped part to be assembled, respectively. The subscripts 1 and 2 represent the serial numbers of at least two embedded parts.

[0055] Measure the distance D along the dimensional chain direction of the newly installed plate-type parts in this process, the number of embedded parts N, the number of assembly mating surfaces M, and the part dimensional tolerance T to form a unit sample:

[0056] [x1,y1,z1,x2,y2,z2,D,N,M,T],

[0057] Wherein, the distance dimension D = d1 + d2, where d1 and d2 are the distance between the plate-type part to be assembled and the assembly datum, and the nominal dimension in the direction of the assembly dimension chain of the plate-type part to be assembled, respectively;

[0058] The number of embedded parts N is the number of embedded parts on the assembly mating surface;

[0059] The number M of assembly mating surfaces is the number of mating surfaces between the newly assembled plate-type part in this process and the model of the previous assembly process after the assembly relationship is established.

[0060] In this embodiment, the specific value of the unit sample is [203,221,0,274,292,0,475,2,2,0.1];

[0061] S3. Repeat S2 to obtain the unit samples of the plate-type parts corresponding to all assembly process models in the assembly dimension chain direction:

[0062] [x i1 ,y i1 ,z i1 ,x i2 ,y i2 ,z i2 D i N i M i ,T i ]

[0063] Wherein, the subscript i represents the number of the i-th assembly process, and is also the number of the plate-shaped part assembled in the i-th assembly process;

[0064] The sample set matrix T is formed by the unit samples of all plate-type parts in the assembly dimension chain direction:

[0065]

[0066] Where n is the total number of assembly processes, i.e., the number of plate-type parts to be assembled. In this embodiment, n is 6, meaning there are six parts to be tested. The sample set matrix is ​​as follows:

[0067]

[0068] Standardize matrix T, and then standardize each element t. ij The value is divided by the sum of the squares of the elements in its column, and then the square root is taken to obtain the corresponding standardized element t'. ij The calculation formula is as follows:

[0069]

[0070] The standardized matrix:

[0071]

[0072] S4. Design an assembly tolerance sensitivity evaluation function based on the TOPSIS algorithm to evaluate matrix T' and obtain the sensitivity score for each plate-type part:

[0073]

[0074] in, For the i-th plate-type part, the minimum sensitivity evaluation value t - Distance between:

[0075]

[0076] For the i-th plate-type part, the maximum sensitivity evaluation value t + Distance between:

[0077]

[0078] in:

[0079]

[0080]

[0081] The distance D between the six parts to be measured and the maximum value + Minimum distance D - and sensitivity score SE i As shown in the table below:

[0082]

[0083] S5, Based on the sensitivity score of sheet metal parts (SE) i Sort the sheet metal parts to be assembled:

[0084] SE1 <SE2<SE3<SE6<SE4<SE5

[0085] Based on the sensitivity characteristics of the evaluation objects to the assembly of plate-type parts, this type of index is a very small index. That is, the higher the sensitivity score of a plate-type part, the higher its assembly tolerance sensitivity, and the greater the impact of its critical dimensions on assembly. Therefore, among the six parts to be tested, part 5 has the highest assembly tolerance sensitivity, and its critical dimensions have the greatest impact on assembly. The sensitivity of the remaining parts, ranked from highest to lowest, is as follows: part 4, part 6, part 3, part 2, and part 1.

[0086] Sensitivity scores reveal the impact of each part on assembly accuracy. Based on this, repair solutions can be recommended, specifically identifying the one or more critical dimensions with the highest scores for dimensional adjustments. This improves the stability and reliability of related components during operation. Compared to traditional methods that rely on worker experience to identify critical dimensions, this approach is significantly more efficient, independent of experience, easy to operate, and yields accurate results.

[0087] This application also provides a parts assembly tolerance sensitivity identification system as described in the above embodiments, including:

[0088] Assembly process model acquisition module: Based on the 3D process design model of the assembly, the assembly dimension chain and assembly sequence are obtained, and the assembly process model corresponding to each process in the assembly process is obtained.

[0089] Sample Construction Module: For each assembly process model, obtain the position coordinates of the newly assembled plate-type parts relative to the assembly datum, the distance dimensions of the plate-type parts along the assembly dimension chain direction, the number of embedded parts, the number of assembly mating surfaces, and the dimensional tolerances of the plate-type parts. Use the position coordinates, distance dimensions, number of embedded parts, and plate-type parts to construct the unit sample for that process. Arrange all unit samples sequentially to form a sample set matrix T. Standardize the sample set matrix T to obtain the standardized matrix T'.

[0090]

[0091] Among them, t' 11 t' 12 t' 13 …t' 1m The first unit sample is the element after standardization. The subscript m is the number of elements contained in each unit sample, and n is the total number of assembly processes, i.e. the number of plate parts to be assembled.

[0092] Sensitivity Evaluation Module: Design an assembly tolerance sensitivity evaluation function based on the TOPSIS algorithm to evaluate matrix T' and obtain the sensitivity score for each plate-type part.

[0093]

[0094] in, For the i-th plate-type part, the minimum sensitivity evaluation value t - Distance between:

[0095]

[0096] For the i-th plate-type part, the maximum sensitivity evaluation value t + Distance between:

[0097]

[0098] in:

[0099]

[0100]

[0101] Based on the sensitivity score SE for plate-type parts i The plate-type parts to be assembled are sorted to obtain a ranking of the degree of influence of the assembly tolerance of each plate-type part on the overall assembly accuracy.

[0102] In summary, this application models the assembly tolerance sensitivity attributes of plate-type parts, including three-dimensional coordinates, nominal dimensions, number of embedded parts, contact surfaces, and tolerances, forming multiple sets of sample data. Based on the TOPSIS algorithm principle, it sorts the samples by detecting the distance between the evaluation object and the optimal and worst solutions, realizing multi-objective decision analysis. The algorithm comprehensively calculates the comprehensive influence factor of each sample on the final assembly tolerance, i.e., sensitivity, and sorts them according to the sensitivity magnitude to obtain the sensitivity of each sample's constituent loop to the final closed loop and the critical assembly dimensions. Adjustments are made based on the identified critical assembly dimensions, thereby improving the assembly efficiency and assembly quality of plate-type parts.

[0103] It will be understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for identifying the sensitivity of assembly tolerances of parts, characterized in that, Based on the three-dimensional process design model of the assembly, the assembly dimension chain and assembly sequence are obtained, and the assembly process model corresponding to each process in the assembly sequence is obtained. For each assembly process model, obtain the position coordinates of the newly assembled plate-type parts relative to the assembly datum, the distance dimension of the plate-type parts along the assembly dimension chain direction, the number of embedded parts in this process, the number of assembly mating surfaces, and the dimensional tolerance of the plate-type parts. The position coordinates, distance dimension, number of embedded parts, and plate-type parts constitute the unit sample of this process. Arrange the unit samples of all processes in order to form a sample set matrix T; Standardize the sample set matrix T to obtain the standardized matrix T': Among them, t' 11 t' 12 t' 13 ...t' 1m The first unit sample is the element after standardization. The subscript m is the number of elements contained in each unit sample, and n is the total number of assembly processes, i.e. the number of plate parts to be assembled. Design an assembly tolerance sensitivity evaluation function based on the TOPSIS algorithm to evaluate matrix T' and obtain the sensitivity score for each plate-type part: in, For the i-th plate-type part, the minimum sensitivity evaluation value t - Distance between: For the i-th plate-type part, the maximum sensitivity evaluation value t + Distance between: in: Based on the sensitivity score SE for plate-type parts i The plate-type parts to be assembled are sorted to obtain a ranking of the degree of influence of the assembly tolerance of each plate-type part on the overall assembly accuracy.

2. The method for identifying the sensitivity of part assembly tolerances according to claim 1, characterized in that, Obtaining the position coordinates of the newly assembled plate-type parts relative to the assembly datum in this process includes: Extract the coordinates of the axis of the center hole of at least two embedded parts on the outermost side of the main assembly mating surface of the plate-type part to be assembled: (x1,y1,z1) and (x2,y2,z2), where the subscripts 1 and 2 represent the serial numbers of at least two embedded parts.

3. The method for identifying the sensitivity of part assembly tolerances according to claim 1, characterized in that, The distance dimension of the plate-type part along the assembly dimension chain direction is characterized by the sum of the distance between the plate-type part to be assembled and the assembly datum and the nominal dimension of the plate-type part in the assembly dimension chain direction.

4. The method for identifying the sensitivity of part assembly tolerances according to claim 1, characterized in that, After standardization, each element of matrix T' is equal to the value of its corresponding element in the sample set matrix T divided by the square root of the sum of the squares of the elements in its column.

5. The method for identifying the sensitivity of part assembly tolerances according to claim 1, characterized in that, Also includes: Based on the ranking of the impact of the assembly tolerances of each plate-type part on the overall assembly accuracy, a repair scheme is obtained, and one or more plate-type parts with a greater impact on the overall assembly accuracy are selected for dimensional repair.

6. A parts assembly tolerance sensitivity identification system, characterized in that, include: Assembly process model acquisition module: Based on the 3D process design model of the assembly, the assembly dimension chain and assembly sequence are obtained, and the assembly process model corresponding to each process in the assembly process is obtained. Sample Construction Module: For each assembly process model, obtain the position coordinates of the newly assembled plate-type parts relative to the assembly datum, the distance dimensions of the plate-type parts along the assembly dimension chain direction, the number of embedded parts, the number of assembly mating surfaces, and the dimensional tolerances of the plate-type parts. Use the position coordinates, distance dimensions, number of embedded parts, and plate-type parts to construct the unit sample for that process. Arrange all unit samples sequentially to form a sample set matrix T. Standardize the sample set matrix T to obtain the standardized matrix T'. Among them, t' 11 t' 12 t' 13 ...t' 1m The first unit sample is the element after standardization. The subscript m is the number of elements contained in each unit sample, and n is the total number of assembly processes, i.e. the number of plate parts to be assembled. Sensitivity Evaluation Module: Design an assembly tolerance sensitivity evaluation function based on the TOPSIS algorithm to evaluate matrix T' and obtain the sensitivity score for each plate-type part. in, For the i-th plate-type part, the minimum sensitivity evaluation value t - Distance between: For the i-th plate-type part, the maximum sensitivity evaluation value t + Distance between: in: Based on the sensitivity score SE for plate-type parts i The plate-type parts to be assembled are sorted to obtain a ranking of the degree of influence of the assembly tolerance of each plate-type part on the overall assembly accuracy.

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