Assembly fixture design method and design system

Abstract

The invention discloses an assembly fixture design method and design system. The assembly fixture design method comprises the following steps: S0, dispersing the design of an assembly fixture into the design of sub-modules; the method comprises the following steps: S1, designing sub-modules, and respectively carrying out sub-module rigidity analysis; s2, the rigidity of the assembly fixture is calculated according to the rigidity of the submodules; and S3, optimizing the structure of the sub-module according to the rigidity calculation result of the assembly fixture, and completing the design of the assembly fixture. The design system comprises a design unit and a rigidity calculation unit, and the rigidity calculation unit is integrated in the design unit. According to the method, the design of the assembly fixture is discretized into the design of the framework, the clamping plate, the positioner and other sub-modules, corresponding general rigidity calculation modules are developed for the sub-modules and integrated to the design platform, designers can conveniently and rapidly carry out rigidity analysis on the sub-modules in the sub-module design stage, and the design efficiency is improved. A large number of design modifications caused by rigidity analysis on the whole assembly jig after design is completed are avoided, and the design period is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of assembly, and in particular relates to an assembly jig design method and a design system. Background Art

[0002] The assembly jig is a process equipment for positioning and clamping components in the industrial production process. It supports the entire process of component manufacturing and equipment, so the quality of the assembly jig directly affects the quality of the product. Stiffness is an important technical indicator for measuring the quality of the assembly jig. At present, the design of the assembly jig mainly adopts a serial working mode. After the designer completes the design of the assembly jig, it will be three-dimensionally modeled. The analyst uses general finite element software to perform stiffness analysis on the assembly jig and feeds back the analysis results to the designer. The designer then modifies the design of the assembly jig based on the feedback results. In this working mode, the designer lacks theoretical support in the initial design and only designs based on experience. After the design is completed, it needs to be redesigned based on the stiffness analysis results, and then the stiffness analysis is re-performed. This repetition leads to a long design cycle and cannot meet the requirements of the production cycle. Summary of the invention

[0003] The object of the present invention is to provide a design method and a design system for an assembly jig, so as to solve the problem that the design cycle of the assembly jig is too long.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for designing an assembly jig comprises the following steps:

[0006] S0, discretizing the design of the assembly jig into the design of submodules; the submodules include a skeleton, a pallet and a positioner;

[0007] S1. Design submodules and perform stiffness analysis on each submodule;

[0008] Submodule stiffness analysis includes:

[0009] S11, calculating the stiffness of the submodule;

[0010] S12, judging whether the stiffness of the submodule meets the requirements;

[0011] S13. If the stiffness of the submodule does not meet the requirements, redesign the submodule;

[0012] S14. Repeat S11, S12, and S13 for the redesigned submodule until the stiffness of the submodule meets the requirements;

[0013] S2. Calculate the stiffness of the assembly jig according to the stiffness of the submodule;

[0014] S3. Optimize the structure of the submodule according to the stiffness calculation results of the assembly jig to complete the design of the assembly jig.

[0015] In some embodiments, the step of calculating the stiffness of the skeleton includes: dividing the skeletons into different skeleton types according to the similarity of the skeletons used in different assembly frames in terms of structure, material, and process; establishing corresponding universal skeleton stiffness calculation models for different skeleton types using the finite element method; and calculating the stiffness of the skeleton using the corresponding universal skeleton finite element stiffness calculation model according to the skeleton type to which the designed skeleton belongs.

[0016] In some embodiments, the step of calculating the stiffness of the pallet includes: establishing a universal pallet stiffness calculation model using the finite element method; and calculating the stiffness of the pallet using the universal pallet stiffness calculation model.

[0017] In some embodiments, the step of calculating the stiffness of the locator includes: establishing a universal locator stiffness calculation model, and using the locator stiffness calculation model to calculate the stiffness of the locator; the universal locator stiffness calculation model simplifies the locator into a cantilever beam model, and calculates the stiffness of the locator based on the cantilever beam model.

[0018] In some embodiments, calculating the stiffness of the assembly jig according to the stiffness of the submodules includes:

[0019] S21, simplifying the assembly frame structure into an ideal structural model consisting of multiple triangular units connected at each node position;

[0020] S22. Under the assumption that each node has only one degree of freedom, obtain the degree of freedom matrix of all nodes;

[0021] S23, calculating the stiffness matrix of each unit according to the node degree of freedom matrix corresponding to each triangular unit;

[0022] S24, superimposing the stiffness matrices of all units to obtain the overall stiffness matrix of the assembly jig;

[0023] S25. Calculate the stiffness of the assembly jig according to the overall stiffness matrix of the assembly jig.

[0024] An assembly jig design system includes: a design unit and a stiffness calculation unit; the stiffness calculation unit is integrated in the design unit; the design unit is used to design submodules and an assembly jig; the stiffness calculation unit includes a skeleton stiffness calculation subunit, a pallet stiffness calculation subunit, a positioner stiffness calculation subunit, and an assembly jig stiffness calculation subunit; the skeleton stiffness calculation subunit is used to calculate the stiffness of the skeleton, the pallet stiffness calculation subunit is used to calculate the stiffness of the pallet, the positioner stiffness calculation subunit is used to calculate the stiffness of the positioner, and the assembly jig stiffness calculation subunit is used to calculate the stiffness of the assembly jig.

[0025] In some embodiments, a stiffness query unit is also included, and the stiffness query unit is used to query the stiffness of the submodule and the assembly jig; the stiffness query unit is integrated into the design unit.

[0026] In some embodiments, the stiffness query unit includes a skeleton stiffness query module, a pallet stiffness query module, a locator stiffness query module, and an assembly jig stiffness query module; the skeleton stiffness query module is used to query the stiffness of the skeleton, the pallet stiffness query module is used to query the stiffness of the pallet, the locator stiffness query module is used to query the stiffness of the locator, and the assembly jig stiffness query module is used to query the stiffness of the assembly jig.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] The present invention discretizes the design of the assembly jig into the design of sub-modules such as a skeleton, a pallet, and a positioner, develops corresponding universal stiffness calculation modules for the sub-modules, and integrates them into a design platform, so that designers can quickly perform stiffness analysis of the sub-modules during the sub-module design stage, avoiding a large number of design modifications caused by performing stiffness analysis on the entire assembly jig after the design is completed, thereby shortening the design cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 Schematic diagram of the skeleton structure in an embodiment of the present invention.

[0031] Figure 2 Schematic diagram of the card board structure in an embodiment of the present invention.

[0032] Figure 3 Schematic diagram of the structure of a positioner in an embodiment of the present invention.

[0033] Figure 4 The figure is a flow chart of an assembly jig design method according to an embodiment of the present invention.

[0034] Figure 5 This is an ideal structural model of an assembly jig according to an embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram of the skeleton stiffness query module interface according to the second embodiment of the present invention.

[0036] Figure 7This is a schematic diagram of the interface of the hole locator stiffness query module according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0038] Embodiment 1

[0039] This embodiment is a method for designing an assembly jig, comprising the following steps:

[0040] S0, discretizing the design of the assembly jig into the design of sub-modules;

[0041] S1. Design submodules and perform stiffness analysis on each submodule;

[0042] S2, calculating the stiffness of the assembly jig according to the stiffness of the submodule;

[0043] S3. Optimize the structure of the submodule according to the stiffness calculation results of the assembly jig to complete the design of the assembly jig.

[0044] According to the requirements of stiffness analysis, the assembly frame is discretized into three different types of sub-modules: frame, pallet, and locator. Figure 1 , Figure 2 , Figure 3 shown.

[0045] By adopting the above method, the stiffness of the submodule is analyzed in the design stage of the submodule, which can make the design of the submodule more accurate. When the stiffness of all submodules meets the requirements, the probability that the stiffness of the assembly jig assembled with them meets the requirements will be greatly increased. Even if the stiffness of the assembled assembly jig does not meet the requirements at the beginning, it can be quickly solved by fine-tuning the submodule. This takes less time than performing stiffness analysis after the assembly jig is designed, and then redesigning the submodule after the analysis, with fewer submodule adjustments and smoother design. In addition, there is no need to repeatedly model the overall assembly jig, which shortens the design cycle from another perspective. The overall deformation of the assembly jig can also be further evaluated based on the deformation data of the assembly jig and the locator. When the requirements are not met, the assembly jig and the locator are adjusted, and the deformation results are re-obtained until the requirements are met.

[0046] The core idea of ​​sub-module stiffness calculation is to establish a universal stiffness calculation model for each sub-module. When the stiffness of the sub-module needs to be calculated, it is only necessary to call the corresponding universal stiffness calculation model.

[0047] In reality, there are many types of skeletons. Some different types of skeletons are highly similar in function and structure. These highly similar skeletons can be divided into different skeleton types using grouping technology. The specific grouping rules can be selected according to actual conditions. In this embodiment, the skeletons are divided into different skeleton types according to the similarity of the skeletons used in different assembly jigs in structure, material, and process. For example, the skeletons of the assembly jigs of aircraft can be divided into four groups, namely horizontal fuselage type, flaperon type, column type, and rotation type. Then, the corresponding universal skeleton stiffness calculation model is established for different skeleton types using the finite element method. After the model is established, the stiffness of the skeleton can be calculated using the corresponding universal skeleton stiffness calculation model according to the skeleton type to which the designed skeleton belongs.

[0048] The specific steps of establishing the corresponding general skeleton stiffness calculation model using the finite element method are as follows: establish a discrete model of the skeleton, which consists of different units, and each unit is connected through nodes outside the unit. The node has geometric properties and physical properties. The stiffness matrix of each unit is solved according to the degree of freedom of each node, and the stiffness matrices of all units are superimposed to obtain the overall stiffness matrix of the skeleton, that is, the stiffness of the skeleton is obtained.

[0049] When solving the stiffness matrix of each unit, it is necessary to solve the control equation, which requires boundary conditions. The control equation is generally a differential equation, which is difficult to solve. Therefore, according to the physical properties of the skeleton and the boundary conditions of the displacement, the approximate solution of the differential equation is solved. The shape of the unit, the shape function of the unit, the material properties, the determination of the boundary conditions, the solution method, etc. are all related to the accuracy of the solution. Therefore, the reasonable grid distribution, material properties, the accuracy of the loads and constraints on the nodes or geometric bodies in the discrete model directly affect the accuracy of the analysis results. To establish a discrete model, it is not necessary to be extremely close in geometry, but to be realistic in performance and have a deep understanding of the physical model.

[0050] The following formula is used when solving the element stiffness matrix.

[0051] The relationship between unit displacement and unit force is: [kee]{ue}={Pe};

[0052] Among them, {ue} is the displacement vector of the node; {Pe} is the external force vector acting on the unit; [kee] is the unit stiffness matrix, and the stiffness matrix of each unit is solved according to this relationship.

[0053] Similar to the frame, the steps for calculating the stiffness of the pallet include: using the finite element method to establish a universal pallet stiffness calculation model; using the universal pallet stiffness calculation model to calculate the stiffness of the pallet.

[0054] The positioner is relatively simple compared to the frame and the pallet, so an analytical method is used to solve its stiffness.

[0055] Specifically, the step of calculating the stiffness of the positioner includes: establishing a universal positioner stiffness calculation model, and using the positioner stiffness calculation model to calculate the stiffness of the positioner, wherein the universal positioner stiffness calculation model simplifies the positioner into a cantilever beam model, and calculates the stiffness of the positioner according to the cantilever beam model.

[0056] According to the analytical method of beam bending perturbation equation, the maximum vertical displacement of the load end can be obtained:

[0057] Where: P is the load, E is the elastic modulus, I is the centroid moment, and l is the length of the beam.

[0058] Taking into account the influence of the shear term, it can be corrected as follows:

[0059] The maximum displacement of the load end after correction is:

[0060] Where: k = 5 / 6, A is the cross-sectional area, and G is the shear modulus.

[0061] From this, the stiffness of the cantilever beam can be calculated as P / v max .

[0062] The rigidity calculation of the assembly jig adopts the discrete model method, and the specific calculation steps are as follows:

[0063] S21, simplifying the assembly frame structure into an ideal structural model consisting of multiple triangular units connected at each node position;

[0064] S22. Under the assumption that each node has only one degree of freedom, obtain the degree of freedom matrix of all nodes;

[0065] S23, calculating the stiffness matrix of each unit according to the node degree of freedom matrix corresponding to each triangular unit;

[0066] S24, superimposing the stiffness matrices of all units to obtain the overall stiffness matrix of the assembly jig;

[0067] S25. Calculate the stiffness of the assembly jig according to the overall stiffness matrix of the assembly jig.

[0068] Assume that the ideal structural discrete model of an assembly jig is as follows Figure 5 As shown in the figure, the structural discrete model consists of 6 triangular elements connecting 7 nodes. Assuming that each node has only one degree of freedom, the degree of freedom of all nodes is:

[0069]

[0070] Among them, u1, u2, u3, u4, u5, u6, and u7 are the degrees of freedom of each node.

[0071] The degree of freedom set of element 1 includes the displacements of nodes 1, 2, and 7, so the displacement degree of freedom set of element 1 can be expressed as:

[0072]

[0073] The stiffness matrices of all elements are superimposed to obtain the overall stiffness matrix.

[0074] Embodiment 2

[0075] This embodiment is an assembly jig design system.

[0076] Since the general assembly jig design system cannot calculate the stiffness, the assembly jig design method described in the first embodiment cannot be used for design. Therefore, the present invention encapsulates the stiffness calculation function into the design system to achieve timely stiffness analysis.

[0077] The design unit is a conventional design platform, such as a CATIA design platform, and a stiffness calculation unit is additionally developed using development languages ​​such as Visual Basic and embedded into the design platform.

[0078] Specifically, the assembly jig design system of this embodiment includes: a design unit and a stiffness calculation unit, wherein the stiffness calculation unit is integrated into the design unit;

[0079] The design unit is used to design submodules and assembly jigs;

[0080] The stiffness calculation unit includes a skeleton stiffness calculation subunit, a pallet stiffness calculation subunit, a positioner stiffness calculation subunit, and an assembly jig stiffness calculation subunit;

[0081] The skeleton stiffness calculation subunit is used to calculate the stiffness of the skeleton, the pallet stiffness calculation subunit is used to calculate the stiffness of the pallet, the positioner stiffness calculation subunit is used to calculate the stiffness of the positioner, and the assembly jig stiffness calculation subunit is used to calculate the stiffness of the assembly jig.

[0082] In addition, in order to facilitate the design of designers, the design system also integrates a stiffness query unit to query the stiffness of sub-modules and assembly jigs.

[0083] Specifically, the stiffness query unit includes a skeleton stiffness query module, a cardboard stiffness query module, a positioner stiffness query module, and an assembly jig stiffness query module;

[0084] The skeleton stiffness query module is used to query the stiffness of the skeleton, the pallet stiffness query module is used to query the stiffness of the pallet, the positioner stiffness query module is used to query the stiffness of the positioner, and the assembly jig stiffness query module is used to query the stiffness of the assembly jig.

[0085] When using the skeleton stiffness query module to query the skeleton stiffness, click on different functional categories and type categories to quickly obtain the stiffness of the skeleton. In this embodiment, the skeleton stiffness query module not only outputs stiffness data, but also outputs deformation cloud maps, and the result file is more intuitive. Figure 6 This is a schematic diagram of the skeleton stiffness query module interface.

[0086] When using the pallet stiffness query module to query the pallet stiffness, you only need to enter the material, span, and width of the pallet, and you can automatically match the pallet type in the pallet library to obtain the pallet stiffness data.

[0087] When using the positioner stiffness query module to query the positioner stiffness, you need to enter the positioner material, force size, positioner cantilever length and profile size to get the positioner stiffness data. In addition, the positioner deformation data can also be automatically obtained. Figure 7 This is a schematic diagram of the locator stiffness query module interface.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for designing an assembly jig, characterized in that: The steps include: S0, discretizing the design of the assembly jig into the design of submodules; the submodules include a frame, a card plate and a positioner; S1. Design submodules and perform stiffness analysis on each submodule; The submodule stiffness analysis includes: S11, calculating the stiffness of the submodule; S12, judging whether the stiffness of the submodule meets the requirements; S13. If the stiffness of the submodule does not meet the requirement, redesign the submodule; S14, repeating S11, S12, and S13 for the redesigned submodule until the stiffness of the submodule meets the requirements; S2, calculating the stiffness of the assembly jig according to the stiffness of the submodule; S3. Optimize the structure of the submodule according to the stiffness calculation results of the assembly jig to complete the design of the assembly jig.

2. The assembly jig design method according to claim 1, characterized in that: The steps to calculate the stiffness of the skeleton include: The frames used in different assembly jigs are divided into different frame types according to the similarity of their structure, material and process; According to the different skeleton types, a corresponding universal skeleton stiffness calculation model is established by using the finite element method; According to the skeleton type to which the designed skeleton belongs, the corresponding general skeleton finite element stiffness calculation model is used to calculate the stiffness of the skeleton.

3. The assembly jig design method according to claim 1, characterized in that: The step of calculating the stiffness of the pallet includes: establishing a universal pallet stiffness calculation model by using the finite element method; and calculating the stiffness of the pallet by using the universal pallet stiffness calculation model.

4. The assembly jig design method according to claim 1, characterized in that: The steps to calculate the stiffness of the positioner include: Establishing a universal positioner stiffness calculation model, and using the positioner stiffness calculation model to calculate the stiffness of the positioner; The general positioner stiffness calculation model simplifies the positioner into a cantilever beam model, and calculates the stiffness of the positioner according to the cantilever beam model.

5. The assembly jig design method according to claim 1, characterized in that: Calculating the stiffness of the assembly jig according to the stiffness of the submodules includes: S21, simplifying the assembly frame structure into an ideal structural model consisting of multiple triangular units connected at each node position; S22. Under the assumption that each node has only one degree of freedom, obtain the degree of freedom matrix of all nodes; S23, calculating the stiffness matrix of each unit according to the node degree of freedom matrix corresponding to each triangular unit; S24, superimposing the stiffness matrices of all units to obtain the overall stiffness matrix of the assembly jig; S25. Calculate the stiffness of the assembly jig according to the overall stiffness matrix of the assembly jig.

6. An assembly jig design system, characterized in that: include: Design unit, stiffness calculation unit; The stiffness calculation unit is integrated into the design unit; The design unit is used to design submodules and assembly jigs; The stiffness calculation unit includes a skeleton stiffness calculation subunit, a cardboard stiffness calculation subunit, a positioner stiffness calculation subunit, and an assembly jig stiffness calculation subunit; The skeleton stiffness calculation subunit is used to calculate the stiffness of the skeleton, the cardboard stiffness calculation subunit is used to calculate the stiffness of the cardboard, the positioner stiffness calculation subunit is used to calculate the stiffness of the positioner, and the assembly jig stiffness calculation subunit is used to calculate the stiffness of the assembly jig.

7. The assembly jig design system according to claim 6, characterized in that: Also included is a stiffness query unit, which is used to query the stiffness of the submodule and the assembly jig; The stiffness query unit is integrated into the design unit.

8. The assembly jig design system according to claim 7, characterized in that: The stiffness query unit includes a skeleton stiffness query module, a cardboard stiffness query module, a positioner stiffness query module, and an assembly jig stiffness query module; The skeleton stiffness query module is used to query the stiffness of the skeleton, the cardboard stiffness query module is used to query the stiffness of the cardboard, the positioner stiffness query module is used to query the stiffness of the positioner, and the assembly jig stiffness query module is used to query the stiffness of the assembly jig.

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