Optimization method for improving rigidity of rotary table

Abstract

The invention discloses an optimization method for improving the rigidity of a rotary table. The optimization method comprises the following steps: 1, forming structural nodes on the top surface and each assembly surface of a rotary table model; 2, loading a torque load / force load at the load position of the top surface; 3, respectively extracting translation displacement and angle displacement of the top surface and each assembly surface in the directions of the three orthogonal coordinate systems; 4, calculating the first rigidity of the structure below the top surface of the turntable and the second rigidity of the structure below each assembly surface; 5, calculating the rigidity of the component between the surfaces; 6, the component corresponding to the minimum component rigidity is judged as the rigidity weak part of the rotary table, and optimization and reinforcement are carried out; and 7, calculating the turntable frequency, comparing the turntable frequency with the first-order frequency of the turntable model, and completing optimization according to a comparison result. According to the method, the rigidity of the rotary table and each component can be quantitatively analyzed, so that the weak rigidity part of the rotary table is specifically found out, optimized and reinforced, and the problem that the weak rigidity part of the rotary table cannot be identified and effectively optimized in the prior art is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of turntable design, and in particular relates to an optimization method for improving the rigidity of a turntable. Background Art

[0002] Complex mechanical assembly equipment such as two-dimensional turntables and pods have requirements for overall modal frequency and assembly stiffness when in use. For example, a turntable for a satellite requires the turntable mechanism to have sufficiently high stiffness to resist interference from the external environment and avoid coupling with the fundamental frequency of other mechanisms. Therefore, it is necessary to ensure that the structural stiffness and fundamental frequency of the turntable meet the design requirements during the design stage.

[0003] At present, the structure of the turntable is relatively complex, which is specifically reflected in the large number of components (parts), different shapes and complex connection relationships, and the structural stiffness of the turntable is now a specific component for load transmission and support, such as bearing adapters, etc. However, the existing technology cannot theoretically calculate and analyze the stiffness and frequency of complex mechanical assemblies and find weak links in the design stage. For example, a single simulation can only obtain the system modal frequency results and loading deformation. The characteristic frequency sweep in the test test stage to obtain the natural frequency of the turntable cannot identify the weak links in the stiffness of the turntable.

[0004] In addition, the patent document with publication number CN105574223A discloses a turntable structure optimization design method based on CAE dynamic analysis, which includes the steps of preliminarily determining the shape, size and wall thickness layout, turntable structure decomposition, preliminary analysis of components, first inspection of design values, overall re-analysis and second inspection of design values. This method uses CAE technology to perform vibration analysis on each module to obtain its natural frequency and vibration mode, and uses reinforcing ribs or structural deformation to increase the natural frequency at locations where the vibration mode is too large. CAE is used to analyze the natural frequency and stress and strain of the overall model to find out the weak links, and the stress and strain values ​​are made to meet the allowable stress value range by changing the structural dimensions, wall thickness and other parameters. However, after careful analysis by the inventor, it was found that this method still has the following technical problems:

[0005] 1. This method requires modal and harmonic response analysis of each component, followed by iterative calculation, which is a large workload. At the same time, it is impossible to compare the contribution of each component to the overall stiffness of the turntable.

[0006] 2. The weak link of the turntable may be a local structure in the component, but this method cannot accurately identify the minimum stiffness structural part that has the greatest impact on the overall stiffness.

[0007] 3. The harmonic loads of the modal and harmonic response analysis of each component in this method may be different from the constraints and loading load positions and directions of the actual overall assembly, resulting in poor accuracy. Summary of the invention

[0008] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide an optimization method for improving the stiffness of a turntable. The present invention combines theory and simulation in the turntable design stage to quantitatively analyze the stiffness of the turntable and its components, thereby specifically finding out the weak parts of the turntable stiffness and optimizing and strengthening them, thereby solving the technical problem that the prior art is unable to identify the weak parts of the turntable stiffness and effectively optimize them.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] An optimization method for improving the rigidity of a turntable comprises the following steps:

[0011] Step S1: three-dimensional modeling of the turntable is performed, and the turntable model is pre-processed in finite element analysis software, and structural nodes are formed on the top surface of the turntable model and the assembly surfaces between the components after the pre-processing;

[0012] Step S2: constraining the bottom surface of the turntable model, and applying a torque load T / force load F to the load position on the top surface of the turntable model;

[0013] Step S3: Coupling nodes are respectively set on the top surface and each assembly surface of the turntable model, and the coupling nodes on the top surface are coupled with the structural nodes on the top surface, and the coupling nodes on the assembly surface are coupled with the structural nodes on the assembly surface; then, a static analysis is performed on the turntable model to extract the translational displacement S and angular displacement θ of the top surface and each assembly surface in the three orthogonal coordinate system directions;

[0014] Step S4: calculating the first stiffness of the structure below the top surface of the turntable according to the torque load T and the angular displacement θ of the top surface of the turntable model / the force load F and the translational displacement S of the top surface of the turntable model, and calculating the second stiffness of the structure below each assembly surface according to the torque load T and the angular displacement θ of each assembly surface;

[0015] Step S5: Calculate the component stiffness between the top surface and the assembly surface, between the assembly surfaces, and between the assembly surface and the bottom surface respectively according to the first stiffness and the second stiffness;

[0016] Step S6: Compare the stiffness of each component, determine that the component corresponding to the minimum component stiffness is the weak part of the turntable stiffness, and optimize and strengthen the weak part of the turntable stiffness;

[0017] Step S7: After optimization and strengthening, calculate the turntable frequency in the direction of the loaded torque load T / force load F, and compare and verify the turntable frequency with the first-order frequency f of the turntable model. If the turntable frequency is greater than the first-order frequency f, the optimization is completed; if the turntable frequency is less than the first-order frequency f, repeat steps S4-S6 until the turntable frequency is greater than the first-order frequency f.

[0018] In step S4, according to the actual structure of the turntable, the turntable model is divided into i faces in sequence according to the arrangement order of the top face, the assembly faces and the bottom face of the turntable. The top face is set as face 1, and the assembly faces are arranged in sequence until the bottom face is face i+1. Then:

[0019] The calculation formula of the first stiffness of the structure below the top surface of the turntable is:

[0020] or

[0021] Where K1 is the first stiffness of the structure below the top surface of the turntable; θ1 is the angular displacement of the top surface of the turntable;

[0022] The calculation formula for the second stiffness of the structure below each assembly surface is:

[0023]

[0024] In the formula, K i It is the first stiffness of the structure below the top surface of the turntable.

[0025] In step S5, the calculation formula for the component stiffness between the top surface and the assembly surface, between the assembly surfaces, and between the assembly surface and the bottom surface is:

[0026]

[0027] In the formula, K (i-1)i is the component stiffness of each component between surface i-1 and surface i.

[0028] In step S7, the bottom surface of the turntable model is constrained, a modal analysis is performed on the turntable model, and the first-order frequency f is obtained through simulation.

[0029] In step S7, the frequency of the turntable is calculated as follows:

[0030]

[0031] Where f1 is the turntable frequency and J is the moment of inertia.

[0032] In step S1, the pre-processing includes sequentially performing structure simplification processing, material setting processing, contact setting processing and meshing processing. After the meshing processing, structural nodes are formed on the top surface of the turntable model and the assembly surfaces between the components.

[0033] In step S3, the assembly surface includes two opposite surfaces, and the coupling node is arranged on any one of the opposite surfaces having a structural node.

[0034] In step S3, the number of coupling nodes on the top surface and each assembly surface is 1 each.

[0035] In step S3, when the translational displacement S and the angular displacement θ are extracted, the top surface and each assembly surface are in the same direction as the loading torque load T / force load F.

[0036] The advantages of adopting the present invention are:

[0037] 1. The present invention combines the theory and simulation in the turntable design stage to perform static and modal analysis on the turntable as a whole. Only one static simulation is needed to quantitatively analyze the stiffness of the turntable and each component, thereby specifically analyzing and calculating the influence of each component on the overall stiffness. The method is simple and reduces a lot of simulation calculation time. In the design stage, the weak parts of the turntable stiffness can be specifically found and optimized and strengthened. It has the advantages of simple calculation process, simple and effective method, no need to analyze each component individually, higher accuracy, good optimization effect and cost saving.

[0038] 2. The present invention combines theory with simulation, and its implementation process is supported by theory and guaranteed by the calculation accuracy of finite element simulation, so it has higher accuracy.

[0039] 3. The present invention is not only applicable to the analysis and optimization and reinforcement of the weak rigidity parts of the turntable, but also applicable to the analysis and optimization and reinforcement of the weak rigidity parts of other serially assembled structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a flowchart of the present invention;

[0041] Figure 2 This is the structural distribution diagram of the turntable;

[0042] Figure 3 This is the coordinate axis diagram of the turntable.

[0043] The markings in the figure are: 1, pitch axis, 2, U-shaped frame, 3, azimuth bearing, 4, motor seat, 5, top surface, 6, assembly surface, 7, bottom surface. DETAILED DESCRIPTION

[0044] Example 1

[0045] The present invention provides an optimization method for improving the rigidity of a turntable, such as Figure 2 , 3 As shown, the turntable includes four main components: a pitch axis 1, a U-shaped frame 2, an azimuth bearing 3, and a motor base 4. The upper surface of the pitch axis 1 is a top surface 5, on which a load can be loaded. There are a total of three assembly surfaces 6 between the pitch axis 1 and the U-shaped frame 2, between the U-shaped frame 2 and the azimuth bearing 3, and between the azimuth bearing 3 and the motor base 4. The lower surface of the motor base 4 is a bottom surface 7.

[0046] Based on the above structure, Figure 1 As shown, the optimization method includes the following steps:

[0047] Step S1: perform three-dimensional modeling on the turntable, import the turntable model into finite element analysis software, perform pre-processing on the turntable model in the finite element analysis software, and form structural nodes on the top surface of the turntable model and the assembly surfaces between the components after the pre-processing.

[0048] Specifically, the pre-processing includes sequentially performing structure simplification processing, material setting processing, contact setting processing and meshing processing. After the meshing processing, structural nodes are formed on the top surface of the turntable model and the assembly surfaces between the components.

[0049] It should be noted that the assembly surface between the turntable components includes two opposite surfaces, and structural nodes can be formed on any one of the opposite surfaces or on both opposite surfaces during meshing.

[0050] Step S2: constrain the bottom surface of the turntable model to keep it stationary, load a torque load T / force load F at the load position on the top surface of the turntable model, and load the torque load T / force load F along the Y-axis direction of the turntable model.

[0051] Step S3: Coupling nodes are respectively set on the top surface and each assembly surface of the turntable model, with one coupling node on the top surface and one coupling node on each assembly surface, and then the coupling nodes on the top surface are coupled with the structural nodes on the top surface, and the coupling nodes on each assembly surface are coupled with the structural nodes on each assembly surface.

[0052] Then, the turntable model is subjected to static analysis, and the translational displacement S and angular displacement θ of the top surface and each assembly surface in the three orthogonal coordinate system directions are extracted using simulation software. Of course, this scheme is not limited to using simulation software to extract the translational displacement S and angular displacement θ, and other conventional extraction methods may be used.

[0053] It should be noted that the assembly surface of the turntable includes two opposite surfaces, and the coupling node is an MPC coupling node, which can be set on any opposite surface with a structural node. When extracting the translational displacement S and the angular displacement θ, the top surface and each assembly surface are consistent with the direction of the loaded torque load T / force load F.

[0054] Step S4: Calculate the first stiffness of the structure below the top surface of the turntable according to the torque load T and angular displacement θ of the top surface of the turntable model / calculate the second stiffness of the structure below each assembly surface according to the torque load T and angular displacement θ of each assembly surface.

[0055] Specifically, according to the actual structure of the turntable, the turntable model is divided into i faces in the order of the top face, the assembly faces and the bottom face of the turntable. The top face is set as face 1, and the assembly faces are arranged in order until the bottom face is face i+1. Then:

[0056] The calculation formula of the first stiffness of the structure below the top surface of the turntable is:

[0057] or

[0058] Where K1 is the first stiffness of the structure below the top surface of the turntable;

[0059] The calculation formula for the second stiffness of the structure below each assembly surface is:

[0060]

[0061] Where K1 is the first stiffness of the structure below the top surface of the turntable.

[0062] Step S5: Calculate the component stiffness between the top surface and the assembly surface, between the assembly surfaces, and between the assembly surface and the bottom surface respectively according to the first stiffness and the second stiffness.

[0063] Specifically, the first stiffness of the structure below the top surface of the turntable obtained in step S4 and the second stiffness of the structure below each assembly surface are substituted into the series stiffness formula to obtain the component stiffness between the top surface and the assembly surface, the component stiffness between each assembly surface, and the component stiffness between the assembly surface and the bottom surface. That is, the component stiffness K of each component between surface i-1 and surface i can be calculated. (i-1)i The series stiffness formula is as follows:

[0064]

[0065] Step S6: Set the stiffness K of each component (i-1)i (i=1,2,3…) are compared to determine that the component corresponding to the minimum component stiffness is the weak part of the turntable stiffness, and then the weak part of the turntable stiffness is optimized and strengthened.

[0066] Step S7: After optimizing and strengthening the weak parts of the turntable stiffness, obtain the first-order frequency f of the turntable model, and calculate the turntable frequency in the direction of the loaded torque load T / force load F, and then compare and verify the turntable frequency with the first-order frequency f of the turntable model. If the turntable frequency is greater than the first-order frequency f, the optimization is completed; if the turntable frequency is less than the first-order frequency f, repeat steps S4-S6 until the turntable frequency is greater than the first-order frequency f.

[0067] It should be noted that the first-order frequency f is obtained by constraining the bottom surface of the turntable model and performing modal analysis and simulation on the turntable model. In practical applications, the acquisition of the first-order frequency f can be completed synchronously in step S2.

[0068] The calculation method of the turntable frequency is:

[0069]

[0070] Where f1 is the turntable frequency and J is the moment of inertia.

[0071] The present invention adopts the above-mentioned specific steps, and through the combination of theory and simulation in the turntable design stage, it can perform quantitative analysis on the stiffness of the turntable and each component, so that the weak points of the turntable stiffness can be specifically found and optimized and strengthened in the design stage, which has the advantages of high accuracy, good optimization effect and cost saving.

[0072] Example 2

[0073] This embodiment combines the attached Figure 2 , 3 , the optimization method of Example 1 is further described in detail.

[0074] according to Figure 2 , 3 The structure shown in the figure, the turntable includes a top surface, a bottom surface and three assembly surfaces between the top surface and the bottom surface. According to the order from top to bottom in the figure, the top surface, the three assembly surfaces and the bottom surface are set as surface 1, surface 2, surface 3, surface 4 and surface 5 respectively. Then the pitch axis 1 is between surface 1 and surface 2, the U-shaped frame 2 is between surface 2 and surface 3, the azimuth bearing 3 is between surface 3 and surface 4, and the motor seat 4 is between surface 4 and surface 5. On this basis,

[0075] Step S1: pre-processing the turntable model. After the pre-processing, grid-shaped structural nodes are formed on surface 1, surface 2, surface 3 and surface 4.

[0076] Step S2: Load a torque load T=60000 N·m at the load position on the top surface of the turntable model, and simulate to obtain a first-order frequency of 33 Hz for the turntable. This embodiment takes loading the torque load T as an example.

[0077] Step S3: MPC coupling nodes are set on surface 1, surface 2, surface 3 and surface 4 respectively, and each MPC coupling node is coupled with the structural node on the corresponding surface respectively, and then the angular displacement θ of each surface in the three orthogonal coordinate system directions is extracted in the simulation software. Specifically, the angular displacement θ of surface 1, surface 2, surface 3 and surface 4 is extracted as follows:

[0078] noodle Surface 1 Surface 2 Surface 3 Surface 4 Angular displacement rad <![CDATA[1.53×10 -4 ]]> <![CDATA[1.17×10 -4 ]]> <![CDATA[7.08×10 -5 ]]> <![CDATA[1.21×10 -5 ]]>

[0079] Step S4: Calculate the first stiffness of the structure below surface 1 according to the torque load T and the angular displacement θ on the top surface of the turntable model

[0080] Then, according to the torque load T and angular displacement θ of surface 2, surface 3 and surface 4, the second stiffness K3 of the structure below each assembly surface is calculated as 5.14×10 8 N·m / rad, third stiffness K5=8.47×108 N·m / rad and the fourth stiffness K4=6.8×10 9 N·m / rad. The fourth stiffness K4 represents the stiffness of the motor base.

[0081] Step S5: Substitute the above four stiffness data into the following series stiffness formulas (1), (2), and (3) to calculate the component stiffness (pitch axis) K between surface 1 and surface 2: 12 =1.65×10 9 N·m / rad, component stiffness between surface 2 and surface 3 (U-frame structure) K 23 =1.3×10 9 N·m / rad, component stiffness between surface 3 and surface 4 (azimuth bearing structure) K 34 =9.68×10 8 N·m / rad. Among them, the component stiffness between surface 4 and surface 5 (motor seat structure) K 45 =K4=6.8×10 9 N·m / rad.

[0082] Step S6: After comparison, K 45 >K 12 >K 23 >K 34 , the component stiffness K between surface 3 and surface 4 34 The value is the smallest, and K is determined 34 The corresponding azimuth bearing structural member is the weak part of the turntable stiffness, and then the weak part is optimized and strengthened. It should be noted that the strain energy of this part can be viewed in the overall modal strain energy mode.

[0083] Step S7: After optimization and strengthening, the turntable frequency is calculated to be 35 Hz, which is greater than the first-order frequency f of 33 Hz. The optimization is completed, and the structural stiffness of the turntable can finally meet the design requirements, thereby achieving the purpose of improving the stiffness of the turntable.

[0084] It can be seen from the above specific implementation process that the present invention quantitatively analyzes the stiffness of the turntable and each component. Each cycle only requires one static simulation and one modal analysis. The steps are simple and can specifically identify the weak points of the turntable stiffness in the design stage and optimize and strengthen them, resulting in better results.

[0085] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all methods or steps in the process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. An optimization method for improving the rigidity of a turntable, characterized in that The following steps are involved: Step S1: three-dimensional modeling of the turntable is performed, and the turntable model is pre-processed in finite element analysis software, and structural nodes are formed on the top surface of the turntable model and the assembly surfaces between the components after the pre-processing; Step S2: constraining the bottom surface of the turntable model, and applying a torque load T / force load F to the load position on the top surface of the turntable model; Step S3: Coupling nodes are respectively set on the top surface and each assembly surface of the turntable model, and the coupling nodes on the top surface are coupled with the structural nodes on the top surface, and the coupling nodes on the assembly surface are coupled with the structural nodes on the assembly surface; then, a static analysis is performed on the turntable model to extract the translational displacement S and angular displacement θ of the top surface and each assembly surface in the three orthogonal coordinate system directions; Step S4: calculating the first stiffness of the structure below the top surface of the turntable according to the torque load T and the angular displacement θ of the top surface of the turntable model / the force load F and the translational displacement S of the top surface of the turntable model, and calculating the second stiffness of the structure below each assembly surface according to the torque load T and the angular displacement θ of each assembly surface; Step S5: Calculate the component stiffness between the top surface and the assembly surface, between the assembly surfaces, and between the assembly surface and the bottom surface respectively according to the first stiffness and the second stiffness; Step S6: Compare the stiffness of each component, determine that the component corresponding to the minimum component stiffness is the weak part of the turntable stiffness, and optimize and strengthen the weak part of the turntable stiffness; Step S7: After optimization and strengthening, calculate the turntable frequency in the direction of the loaded torque load T / force load F, and compare and verify the turntable frequency with the first-order frequency f of the turntable model. If the turntable frequency is greater than the first-order frequency f, the optimization is completed; if the turntable frequency is less than the first-order frequency f, repeat steps S4-S6 until the turntable frequency is greater than the first-order frequency f.

2. The optimization method for improving the rigidity of a turntable according to claim 1, characterized in that: In step S4, according to the actual structure of the turntable, the turntable model is divided into i faces in sequence according to the arrangement order of the top face, the assembly faces and the bottom face of the turntable. The top face is set as face 1, and the assembly faces are arranged in sequence until the bottom face is face i+1. Then: The calculation formula of the first stiffness of the structure below the top surface of the turntable is: or Where K1 is the first stiffness of the structure below the top surface of the turntable; θ1 is the angular displacement of the top surface of the turntable; The calculation formula for the second stiffness of the structure below each assembly surface is: In the formula, K i It is the first stiffness of the structure below the top surface of the turntable.

3. The optimization method for improving the rigidity of a turntable according to claim 2, characterized in that: In step S5, the calculation formula for the component stiffness between the top surface and the assembly surface, between the assembly surfaces, and between the assembly surface and the bottom surface is: In the formula, K (i-1)i is the component stiffness of each component between surface i-1 and surface i.

4. The optimization method for improving the rigidity of a turntable according to claim 1, characterized in that: In step S7, the bottom surface of the turntable model is constrained, a modal analysis is performed on the turntable model, and the first-order frequency f is obtained through simulation.

5. An optimization method for improving turntable rigidity according to any one of claims 2 to 4, characterized in that: In step S7, the frequency of the turntable is calculated as follows: Where f1 is the turntable frequency and J is the moment of inertia.

6. The optimization method for improving the rigidity of a turntable according to claim 1, characterized in that: In step S1, the pre-processing includes sequentially performing structure simplification processing, material setting processing, contact setting processing and meshing processing. After the meshing processing, structural nodes are formed on the top surface of the turntable model and the assembly surfaces between the components.

7. The optimization method for improving the rigidity of a turntable according to claim 1, characterized in that: In step S3, the assembly surface includes two opposite surfaces, and the coupling node is arranged on any one of the opposite surfaces having a structural node.

8. The optimization method for improving the rigidity of a turntable according to claim 1, characterized in that: In step S3, the number of coupling nodes on the top surface and each assembly surface is 1 each.

9. The optimization method for improving the rigidity of a turntable according to claim 1, characterized in that: In step S3, when the translational displacement S and the angular displacement θ are extracted, the top surface and each assembly surface are in the same direction as the loading torque load T / force load F.

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