CN111985122A - Part tolerance optimization design method - Google Patents
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- CN111985122A CN111985122A CN202010645315.7A CN202010645315A CN111985122A CN 111985122 A CN111985122 A CN 111985122A CN 202010645315 A CN202010645315 A CN 202010645315A CN 111985122 A CN111985122 A CN 111985122A
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- 238000004458 analytical method Methods 0.000 claims description 44
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- 238000011156 evaluation Methods 0.000 claims description 4
- 230000000712 assembly Effects 0.000 claims description 3
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- 230000009897 systematic effect Effects 0.000 claims description 3
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- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
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- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/17—Mechanical parametric or variational design
Abstract
The invention provides a part tolerance optimization design method considering a dimension engineering technology, which comprises the following steps: designing part characteristic tolerance, equalizing errors in the assembly process, analyzing tolerance, modeling non-ideal parts, analyzing assembly deformation finite elements and evaluating key characteristics of an assembly body. The method can analyze and evaluate the product design tolerance in the structural design stage, considers assembly process errors such as tooling errors, operation errors and positioning errors, simultaneously considers part assembly deformation and the like caused by assembly force in the assembly process, solves the difficult problem that parts are difficult to mount and even cannot be mounted, analyzes the rationality of tolerance design and the assembly performance of parts in advance in the design stage, and reduces the development cost.
Description
Technical Field
The invention belongs to the field of optimization of product structure design, and particularly relates to a method for optimizing the structure tolerance design of an aircraft.
Background
In the whole life cycle process of the product, the product design stage has an important position and directly influences each stage of subsequent product manufacturing, assembly, operation and maintenance and the like. The product design process requires designing not only the structural form of the part but also for the critical surface feature tolerances of the part. The rationality of the surface tolerance of the part directly affects the manufacturing cost and the processing period of the product, the strict surface tolerance increases the manufacturing cost and the manufacturing period of the part, the production efficiency of a manufacturing factory is reduced, and the loose surface tolerance does not meet the functional requirements of the product. Therefore, in the design process of the aircraft structure, how to design a more reasonable surface feature tolerance has important significance.
In the design phase, dimensional engineering techniques are mostly used in order to analyze the rationality of the surface feature tolerances. The dimension engineering runs through product design stages such as product concept design, detailed design and the like, is an engineering method and means combining a computer simulation technology, and utilizes statistical analysis, computer aided design, simulation software and the like to design and optimize product tolerance. Tolerance analysis is the main content of dimensional engineering, is the core of dimensional engineering, and is very important for guaranteeing the assembly of design models. The key characteristics of the product are used as indexes which can represent the functions/performances of the product, and the influence of the design tolerance of the parts on the key characteristics of the product is mainly analyzed in the tolerance analysis process. All relevant surface tolerances affecting the key characteristics of the product can be judged through tolerance analysis, whether the key characteristics meet the design requirements can be judged, the proportion of the influence of each surface tolerance on the key characteristics of the product can be analyzed, and then the relevant surface feature tolerances are optimized.
At present, the tolerance analysis process is mostly carried out according to the part surface tolerance marking information, although the influence of the surface feature tolerance information on the key characteristics of the product can be analyzed, the analysis result does not take all influence factors into consideration, such as errors generated by interaction among the part assembly characteristics and assembly errors generated in the actual assembly process, for example, tool shape errors, personnel operation errors and the like into consideration, and the analysis result and the actual state of the product still have some differences.
Disclosure of Invention
The invention provides a part tolerance optimization design method considering a dimension engineering technology, which can analyze design tolerance in advance in a design stage and realize optimization of a part design process.
A part tolerance optimization design method comprises the following steps:
s1: part feature tolerance design
And marking tolerance information of the surface features of the designed parts according to the international tolerance standard, wherein the international tolerance standard is ISO16792 or ASMEY 14.5.
S2: error equivalence in assembly process
And analyzing errors generated in the assembly process of the part, and equating the errors generated in the assembly process to be part surface tolerances, wherein the errors generated in the assembly process comprise operation errors, tool manufacturing errors and positioning errors.
S3: tolerance analysis
Stacking the equivalent part surface tolerance in the step S2 and the marked tolerance in the step S1, constructing an assembly constraint relation between parts, setting key characteristics of an assembly body, establishing a tolerance analysis model, and performing tolerance analysis, wherein the key characteristics of the assembly body are established to meet the product performance requirements; including dimensional requirements, angular requirements.
S4: non-ideal part modeling
And generating a non-ideal surface by adopting a non-ideal surface modeling method, and establishing a non-ideal part model.
S5: assembly deformation finite element analysis
And (4) analyzing the actual assembly process of the part by taking the non-ideal part model established in the step S4 as input, establishing a part assembly finite element analysis model, setting boundary conditions which are consistent with actual assembly, carrying out contact analysis to obtain an assembly characteristic surface displacement result, and deriving relevant data of each node on the surface, wherein the relevant data comprises a space coordinate value of each node and displacement in the direction of each coordinate axis.
S6: assessment of key characteristics of assemblies
And (4) overlapping the tolerance analysis result in the step S3 with the finite element analysis result derived in the step S5, evaluating key characteristics of the assembly body, feeding the evaluation result back to the tolerance design process, analyzing the rationality of the tolerance design, and optimizing the product tolerance design process.
Further, the tolerance information labeling in the step S1 satisfies the independent principle.
Further, when the errors generated during the assembly process are analyzed in the step S2, the analysis is performed by a variety of samples for each error, and then the average value is obtained.
Further, the non-ideal surface modeling method in S4, which includes a non-ideal surface modeling method based on manufacturing error factors, that divides surface deviations into systematic deviations and random deviations, is constrained using part surface feature tolerances.
Further, when the non-ideal surface is generated by the non-ideal surface modeling method based on the manufacturing error factors, the influence of each manufacturing error factor on the machined surface is analyzed according to a test for different machining methods.
Further, in the finite element analysis with the non-ideal part as an input in S5, the contact surface is frictionless.
Further, the tolerance design rationality is evaluated in step S6 by analyzing the three-dimensional tolerance band region of the part feature surface.
The invention not only considers the design tolerance marked in the part design process, but also considers the equivalent tolerance generated in the assembly process and the surface deformation generated under the action of external force in the part assembly process, and simulates the part assembly process and form to the maximum extent, so that the analysis process is more consistent with the actual assembly state, and the assembly body evaluation accuracy and the product design quality are improved.
Drawings
FIG. 1 is a schematic diagram of a part tolerance optimization design method in consideration of the dimension engineering technology;
FIG. 2 is a front view of an embodiment of the present invention;
fig. 3 is a right cut-away view of an embodiment of the present invention.
In the figure 1, a mounting table; 2. assembling; 3. a first part to be mounted; 4. mounting screws; 5. and a second part to be mounted.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The invention provides a part tolerance optimization design method considering a dimension engineering technology, wherein the dimension engineering technology involved in the method is a generalized dimension engineering technology, and errors generated by interaction between assembly characteristics and assembly errors generated in an actual assembly process are considered, so that an analysis result is more reasonable and more accords with an actual assembly state, and a more reasonable surface characteristic tolerance is designed for a part.
As shown in FIG. 1, the invention relates to a part tolerance optimization design method, which comprises the following steps:
1) part feature tolerance design
Marking tolerance information of the surface features of the designed part according to an international tolerance standard (ISO16792 or ASMEY 14.5);
2) error equivalence in assembly process
Analyzing errors generated in the assembling process, including operation errors, tool manufacturing errors, positioning errors and the like, and equating the errors generated in the assembling process to be part surface tolerances;
3) tolerance analysis
Stacking equivalent part surface tolerance and marked tolerance, constructing an assembly constraint relation between parts, setting key characteristics (such as size requirements, angle requirements and the like) of an assembly body, establishing a tolerance analysis model, and performing tolerance analysis; establishing key characteristics of the assembly body, wherein the key characteristics need to meet product performance requirements and are converted from the product performance requirements;
4) non-ideal part modeling
Generating a non-ideal surface by adopting a non-ideal surface modeling method (such as a non-ideal surface modeling method which divides surface deviation into system deviation and random deviation and is based on manufacturing error factors), and establishing a non-ideal part model; in the process of generating the non-ideal surface, the characteristic tolerance of the part surface is adopted for constraint so as to ensure that the generated non-ideal surface meets the tolerance requirement;
5) assembly deformation finite element analysis
The non-ideal surface modeling method includes a non-ideal surface modeling method that divides surface deviations into systematic deviations and random deviations based on manufacturing error factors. When the non-ideal surface is generated by the non-ideal surface modeling method based on the manufacturing error factors, the influence of each manufacturing error factor on the processing surface can be analyzed according to tests aiming at different processing methods;
analyzing the actual assembly process of the part by taking a non-ideal part model as input, establishing a part assembly finite element analysis model and an analysis flow, setting boundary conditions and the like which are matched with actual assembly, carrying out contact analysis to obtain an assembly characteristic surface displacement result, and deriving relevant data of each node on the surface, including space coordinate values of each node and displacement in the direction of each coordinate axis; when the non-ideal part is used as input for finite element analysis, the contact surface is frictionless;
6) assessment of key characteristics of assemblies
And (3) superposing a tolerance analysis result and a derived finite element analysis result, evaluating key characteristics of the assembly body, feeding the evaluation result back to the tolerance design process, analyzing the rationality of the tolerance design, optimizing the product tolerance design process, and improving the rationality and performance requirements of the product design.
The following is a detailed description of a specific embodiment:
firstly, tolerance design is carried out on the surface of a part to be assembled, particularly the surface serving as an assembly characteristic, and the marked tolerance meets an independent principle;
in the embodiment of the invention, as shown in fig. 2 and 3, an installation table 1 is a fixed part, a tool 2 is installed on the installation table 1, a second part to be installed 5 is clamped on the tool, and a first part to be installed 3 and the second part to be installed 5 are fastened and connected by screws.
Analyzing errors in the assembling process, taking the embodiment as an example, analyzing manufacturing errors of the tool 2, positioning errors of the first part to be installed 3 and operation errors of operators in the assembling process of the tool and the parts, obtaining error distribution ranges through multiple measurements or assuming various error distribution rules and sizes according to experience, equating errors generated in the assembling process to be part surface tolerances, and meanwhile, overlapping the part surface tolerances with the marked surface tolerances.
Establishing key characteristics of an assembly body, taking an embodiment as an example, the assembly characteristics of the first part to be mounted 3 and the second part to be mounted 5 can be the assembly performance of the two parts, setting the relative position of the axis of the conventional hole of the first part to be mounted 3 and the axis of the threaded hole of the second part to be mounted 5 as the key characteristics of the assembly body, establishing a tolerance analysis model, and performing tolerance analysis.
The non-ideal surface is generated by adopting a non-ideal surface modeling method, taking an embodiment as an example, the non-ideal surface modeling method is adopted to establish the non-ideal surface of the contact surface pair of the first part to be installed 3 and the second part to be installed 5, the non-ideal first part to be installed 3 and the non-ideal second part to be installed 5 are used as input to establish a finite element analysis model, contact analysis is carried out, the displacement deviation of the contact surface pair of the first part to be installed 3 and the second part to be installed 5 generated by the two non-ideal surfaces under the condition of the specified torque of the installation screw is analyzed, and meanwhile, the displacement result is exported.
And superposing the tolerance analysis result and the finite element analysis result, calculating the relative position between the first part to be mounted 3 and the second part to be mounted 5, determining the relative position between the conventional hole axis of the first part to be mounted 3 and the threaded hole axis of the second part to be mounted 5, and analyzing whether the design requirements are met.
The invention analyzes the design tolerance of the parts in advance in the design stage, not only considers the error generated by the operation of an assembling person or the positioning of the parts in the assembling process, but also considers the change of the positions of the assembled parts caused by the influence of the assembling force, so that the analysis state is more consistent with the real assembling process, the rationality of tolerance design is analyzed in advance, the assemblability of the parts is realized, the problems in the manufacturing and assembling process of the parts are reduced, the research and development period of the products is shortened, and the product performance is improved.
The above-mentioned specific implementation procedures are only for explaining and explaining the technical solution of the present invention, but should not be construed as limiting the scope of the claims. It should be clear to those skilled in the art that any simple modification or replacement based on the technical solution of the present invention may be adopted to obtain a new technical solution, which falls within the scope of the present invention.
Claims (7)
1. A method of designing a part for tolerance optimization, the method comprising the steps of:
s1: part feature tolerance design
Marking tolerance information of the surface features of the designed parts according to an international tolerance standard, wherein the international tolerance standard is ISO16792 or ASME Y14.5;
s2: error equivalence in assembly process
Analyzing errors generated in the assembly process of the part, and equating the errors generated in the assembly process to be part surface tolerances, wherein the errors generated in the assembly process comprise operation errors, tool manufacturing errors and positioning errors;
s3: tolerance analysis
Stacking the equivalent part surface tolerance in the step S2 and the marked tolerance in the step S1, constructing an assembly constraint relation between parts, setting key characteristics of an assembly body, establishing a tolerance analysis model, and performing tolerance analysis, wherein the key characteristics of the assembly body are established to meet the product performance requirements; including dimensional requirements, angular requirements;
s4: non-ideal part modeling
Generating a non-ideal surface by adopting a non-ideal surface modeling method, and establishing a non-ideal part model;
s5: assembly deformation finite element analysis
Analyzing the actual assembly process of the part by taking the non-ideal part model established in the step S4 as input, establishing a part assembly finite element analysis model, setting boundary conditions which are consistent with actual assembly, carrying out contact analysis to obtain an assembly characteristic surface displacement result, and deriving relevant data of each node on the surface, wherein the relevant data comprises a space coordinate value of each node and displacement in the direction of each coordinate axis;
s6: assessment of key characteristics of assemblies
And (4) overlapping the tolerance analysis result in the step S3 with the finite element analysis result derived in the step S5, evaluating key characteristics of the assembly body, feeding the evaluation result back to the tolerance design process, analyzing the rationality of the tolerance design, and optimizing the product tolerance design process.
2. The method for optimally designing the tolerance of the part according to claim 1, wherein the tolerance information labels in the step S1 satisfy independent principles.
3. The method for optimally designing the tolerance of a part according to claim 1, wherein the step S2 is performed by analyzing a plurality of samples for each error and then averaging the samples.
4. The part tolerance optimization design method according to claim 1, wherein the non-ideal surface modeling method in S4 is constrained by part surface feature tolerances, and the non-ideal surface modeling method comprises a non-ideal surface modeling method based on manufacturing error factors, and the non-ideal surface modeling method is divided into systematic deviations and random deviations.
5. The method of claim 4, wherein when the non-ideal surface is generated by a non-ideal surface modeling method based on the manufacturing error factors, the influence of each manufacturing error factor on the machined surface is analyzed according to a test for different machining methods.
6. A method for optimally designing tolerances of parts according to claim 1, wherein the contact surface is frictionless when performing finite element analysis with non-ideal parts as input in S5.
7. The method for optimally designing the tolerance of the part according to claim 1, wherein the rationality of the tolerance design is evaluated by analyzing the three-dimensional tolerance band region of the characteristic surface of the part in the step S6.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116384257A (en) * | 2023-05-29 | 2023-07-04 | 浙江大学 | Method for predicting assembly errors and optimizing tolerance of air separation integral cold box |
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| CN107247841A (en) * | 2017-06-09 | 2017-10-13 | 北京理工大学 | A kind of rectangular spline Contact Dynamics emulation mode based on assembly features information |
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Cited By (2)
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| CN116384257A (en) * | 2023-05-29 | 2023-07-04 | 浙江大学 | Method for predicting assembly errors and optimizing tolerance of air separation integral cold box |
| CN116384257B (en) * | 2023-05-29 | 2023-09-29 | 浙江大学 | Method for predicting assembly errors and optimizing tolerance of air separation integral cold box |
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