Thin-wall structure milling boss clamping layout optimization method considering feeding path

Abstract

The invention belongs to the technical field of machining, and particularly relates to a thin-wall structure milling boss clamping layout optimization method considering a feeding path. The method comprises the steps that multiple boss clamping layout schemes are obtained; constructing a thin-wall blank finite element model, and performing finite element calculation to obtain initial residual stress data; building a thin-wall blank milling boss clamping finite element model according to different boss clamping layout schemes, performing grid division, and applying the initial residual stress data to the thin-wall blank milling boss clamping finite element model; a milling feed path is selected, milling force is gradually applied to a milled unit of the thin-wall blank milling boss clamping finite element model according to the advancing distance of a milling cutter, the milling process is simulated, and machining deformation data and residual stress data are obtained; and determining optimal technical indexes of the boss clamping layout scheme, and screening out the boss clamping layout scheme meeting the requirements according to the technical indexes, the machining deformation data and the residual stress data.

Description

Technical Field

[0001] The present application belongs to the field of mechanical processing technology, and in particular relates to a method for optimizing the clamping layout of a thin-walled structure milling boss taking into account a tool path. Background Art

[0002] Thin-walled structural parts have the characteristics of large volume, poor local stiffness, and high material removal rate. Therefore, large overall machining deformation may occur after the workpiece is processed. The main reason is the release and redistribution of residual stress in the blank caused by high material removal rate. There are usually three sources of machining deformation of thin-walled structural parts: the release of residual stress of removed materials, the milling effect of the tool on the workpiece (including milling force and tool path), and the clamping conditions of the workpiece during milling. Using a reasonable clamping method and optimizing the clamping scheme is an effective way to control the overall machining deformation of thin-walled structures.

[0003] Designing a process boss on the side of the part to clamp the workpiece is a common way to clamp thin-walled structures. In the specific processing process, the workpiece can be fixed on the machine tool table by clamping the plate or pre-tightening the bolts to achieve the purpose of clamping the workpiece, and the process boss can be cut off after the completion. When designing the workpiece clamping scheme, if there are too few process bosses, it may cause the problem of excessive deformation during the part processing. If there are too many bosses, it may cause the secondary release of the residual stress of the workpiece and cause large deformation of the workpiece. In addition, the position of the process boss has an important influence on the size and distribution of the processing deformation. Therefore, the number and position of the process boss should be optimized in advance. However, optimization through experimental methods is not only time-consuming and laborious, but also difficult to consider the change of residual stress. Numerical simulation can avoid the above problems to a certain extent. Among them, the three-dimensional dynamic finite element method is the most common milling simulation method, which is used in the special milling software AdvantEdge and Deform Machining, but the calculation efficiency is low, it is difficult to quickly and accurately realize the full-size processing deformation simulation analysis of large thin-walled structural parts, and it is difficult to consider the influence of the tool path.

[0004] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention

[0005] The purpose of the present application is to provide a method for optimizing the clamping layout of a thin-walled structure milling boss taking into account the tool path, so as to solve at least one problem existing in the prior art.

[0006] The technical solution of this application is:

[0007] A method for optimizing the clamping layout of a thin-walled structure milling boss considering a tool path, comprising:

[0008] Step 1: Obtain various boss clamping layout solutions;

[0009] Step 2: construct a finite element model of the thin-walled blank and perform finite element calculation to obtain initial residual stress data;

[0010] Step 3, constructing a finite element model of the milling boss clamping of a thin-walled blank according to different boss clamping layout schemes, determining a grid size according to milling parameters, and meshing the finite element model of the milling boss clamping of the thin-walled blank according to the grid size, and applying the initial residual stress data to the finite element model of the milling boss clamping of the thin-walled blank;

[0011] Step 4: Select a milling tool path, and based on the milling tool path, gradually apply the milling force to the milled unit of the milling boss clamping finite element model of the thin-walled blank according to the milling tool path according to the milling cutter advance distance, so as to simulate the milling process and obtain machining deformation data and residual stress data;

[0012] Step 5: Determine the optimal technical indicators of the boss clamping layout scheme, and screen out the boss clamping layout scheme that meets the requirements based on the technical indicators, the processing deformation data and the residual stress data.

[0013] In at least one embodiment of the present application, in step 1, a plurality of boss clamping layout solutions are obtained, including:

[0014] Determine the optimal factors of boss clamping layout scheme that affect the milling deformation of thin-walled structures, and construct the optimal factor table;

[0015] Determine the level number corresponding to each of the preferred factors;

[0016] Based on the orthogonal test principle, an orthogonal table of boss clamping layout schemes is constructed to obtain a variety of boss clamping layout schemes.

[0017] In at least one embodiment of the present application, the preferred factors include the number of bosses, boss positions, and boss sizes.

[0018] In at least one embodiment of the present application, in step 2, a finite element model of a thin-walled blank is constructed, and finite element calculation is performed to obtain initial residual stress data, including:

[0019] The sequential coupling method is used to perform finite element simulation on the blank, determine the material's nonlinear physical properties and high-temperature mechanical properties with temperature, determine the solution quenching process, and construct a finite element model of the thin-walled blank;

[0020] Boundary conditions are applied to the finite element model of the thin-walled blank, and a temperature load is applied to the finite element model of the thin-walled blank, and finite element calculation is performed to obtain initial residual stress data.

[0021] In at least one embodiment of the present application, in step three, a finite element model of a milling boss clamping of a thin-walled blank is constructed according to different boss clamping layout schemes, a grid size is determined according to milling parameters, and the finite element model of the milling boss clamping of the thin-walled blank is meshed according to the grid size, and the initial residual stress data is applied to the finite element model of the milling boss clamping of the thin-walled blank, including:

[0022] Constructing a finite element model of a milling boss clamping of a thin-walled blank according to different boss clamping layout schemes, wherein the finite element model of a milling boss clamping of a thin-walled blank comprises a thin-walled blank unit and a boss unit, and the thin-walled blank unit comprises a milled unit and a part unit;

[0023] The milling depth is used as the grid size in the depth direction, the milling width is used as the grid size in the width direction, and the milling cutter advance distance is used as the grid size in the milling cutter advance direction, and the thin-walled blank unit in the finite element model of the thin-walled blank milling boss clamping is meshed according to the determined grid size;

[0024] According to the solution accuracy requirement, the thin-walled blank unit in the thin-walled blank milling boss clamping finite element model is divided into several layers along the thickness direction by meshing;

[0025] The initial residual stress applied to each layer of the thin-walled blank unit is determined according to the initial residual stress data.

[0026] In at least one embodiment of the present application, in step 4, a milling tool path is selected, and based on the milling tool path, a milling force is gradually applied to the milled unit of the milling boss clamping finite element model of the thin-walled blank according to the milling tool advance distance, so as to simulate the milling process and obtain machining deformation data and residual stress data, including:

[0027] Select the milling path;

[0028] According to the milling parameters, the milling cutter advance distance and milling force are calculated respectively, among which,

[0029] The distance the milling cutter advances in each feed step is:

[0030]

[0031] Among them, d w is the distance the milling cutter moves forward, R is the radius of the milling cutter, a e is the milling width;

[0032] The milling force is:

[0033]

[0034] Fi ∈(F x , F y , F z )

[0035] Among them, F i is the milling force, is the milling force coefficient, n is the milling speed, a p is the milling depth, is the exponential coefficient corresponding to the milling speed n, is the milling depth a p The corresponding exponential coefficient is, The distance d that the milling cutter advances w The corresponding exponential coefficient is, is the exponential coefficient corresponding to the milling cutter radius R;

[0036] Based on the milling tool path, the milling force is gradually applied to the milled unit of the thin-walled blank milling boss clamping finite element model according to the milling cutter advance distance, so as to simulate the milling process and obtain machining deformation data and residual stress data.

[0037] In at least one embodiment of the present application, the milling tool path is one of transverse sequential milling, longitudinal sequential milling, transverse S-shaped milling, longitudinal S-shaped milling, spiral milling from outside to inside, and spiral milling from inside to outside.

[0038] In at least one embodiment of the present application, in step 5, determining the preferred technical indicators of the boss clamping layout scheme, and screening out the boss clamping layout scheme that meets the requirements according to the technical indicators, the processing deformation data and the residual stress data, including:

[0039] Determine the technical indicators for the optimal boss clamping layout scheme;

[0040] Determining the value of the technical indicator according to the processing deformation data and the residual stress data;

[0041] Calculate the average value of a technical indicator:

[0042]

[0043] in, is the average technical index of the vth optimal factor pair at the uth level, K uv is the technical indicator of the uth level and the vth optimal factor pair, h v is the number of levels of the vth preferred factor;

[0044] Calculate the range of a technical indicator:

[0045]

[0046] Among them, R v is the extreme difference of technical indicators. for The maximum value of for The minimum value of

[0047] According to the extreme difference of technical indicators, the boss clamping layout scheme that meets the requirements is screened out.

[0048] In at least one embodiment of the present application, the technical indicators include maximum machining deformation, average machining deformation, and maximum residual stress.

[0049] The invention has at least the following beneficial technical effects:

[0050] The preferred method for the clamping layout of thin-walled structure milling bosses considering the tool path of the present application can simultaneously consider the coupling effect of the tool path and the process boss, and can also comprehensively evaluate multiple technical indicators to ultimately obtain an optimal boss clamping layout solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a flow chart of a method for optimizing the clamping layout of a boss for milling a thin-walled structure considering a tool path according to an embodiment of the present application;

[0052] Figure 2 It is a schematic diagram of a finite element model of a milling boss clamping of a thin-walled blank according to an embodiment of the present application;

[0053] Figure 3 is a schematic diagram of a milling tool path according to an embodiment of the present application;

[0054] Figure 4 is a schematic diagram of a milling process according to an embodiment of the present application;

[0055] Figure 5 It is a schematic diagram of finite element simulation results of a finite element model for clamping a milling boss of a thin-walled blank according to an embodiment of the present application. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0057] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0058] The following is combined with Figures 1 to 5 This application is described in further detail.

[0059] The present application provides a method for optimizing the clamping layout of a thin-walled structure milling boss considering a tool path, comprising the following steps:

[0060] Step 1: Obtain various boss clamping layout solutions;

[0061] Step 2: construct a finite element model of the thin-walled blank and perform finite element calculation to obtain initial residual stress data;

[0062] Step 3: construct a finite element model of the milling boss clamping of the thin-walled blank according to different boss clamping layout schemes, determine the grid size according to the milling parameters, and mesh the finite element model of the milling boss clamping of the thin-walled blank according to the grid size, and apply the initial residual stress data to the finite element model of the milling boss clamping of the thin-walled blank;

[0063] Step 4: Select a milling path, and based on the milling path, gradually apply the milling force to the milled unit of the finite element model of the milling boss clamping of the thin-walled blank according to the milling cutter advance distance, so as to simulate the milling process and obtain the processing deformation data and residual stress data;

[0064] Step 5: Determine the optimal technical indicators for the boss clamping layout scheme, and screen out the boss clamping layout scheme that meets the requirements based on the technical indicators, processing deformation data and residual stress data.

[0065] The present application discloses a method for optimizing the boss clamping layout for thin-walled structure milling considering the tool path. First, in step 1, a plurality of boss clamping layout schemes are obtained, which specifically includes the following processes:

[0066] Determine the optimal factors of boss clamping layout scheme that affect the milling deformation of thin-walled structures, and construct the optimal factor table;

[0067] Determine the number of levels corresponding to each preferred factor;

[0068] Based on the orthogonal test principle, an orthogonal table of boss clamping layout schemes is constructed to obtain a variety of boss clamping layout schemes.

[0069] The boss clamping layout scheme is designed according to the processing experience, the orthogonal experimental method is used to select the process optimization factors and the corresponding level numbers, and the orthogonal table of the process optimization experimental scheme is constructed. For the same processing task, various possible boss clamping layout schemes such as boss number, boss position and boss size are designed.

[0070] The present application's thin-walled structure milling boss clamping layout optimization method considering the tool path, secondly, in step 2, a thin-walled blank finite element model is constructed, and finite element calculation is performed to obtain initial residual stress data, specifically including:

[0071] The sequential coupling method is used to perform finite element simulation on the blank, determine the material's nonlinear physical properties and high-temperature mechanical properties with temperature, determine the solution quenching process, and construct a finite element model of the thin-walled blank;

[0072] Boundary conditions are applied to the finite element model of the thin-walled blank, and temperature loads are applied to the finite element model of the thin-walled blank. Finite element calculation is performed to obtain initial residual stress data.

[0073] The sequential coupling method is used to perform finite element simulation on the initial blank. The physical parameters and high-temperature mechanical properties of the material that change nonlinearly with temperature are specified. The specific process measures for solid solution quenching are selected, and a finite element model of the thin-walled blank is established. The temperature field during the entire heat treatment process is simulated, and the temperature field is imported into the transient mechanical analysis in the form of load. Boundary conditions are imposed according to the actual clamping conditions, and the residual stress field caused by uneven temperature changes is calculated.

[0074] The present application discloses a method for optimizing the clamping layout of a thin-walled structure milling boss considering a tool path. In step 3, a finite element model of a thin-walled blank milling boss clamping is constructed according to different boss clamping layout schemes, a mesh size is determined according to milling parameters, and the finite element model of the thin-walled blank milling boss clamping is meshed according to the mesh size, and initial residual stress data is applied to the finite element model of the thin-walled blank milling boss clamping, including:

[0075] According to different boss clamping layout schemes, a finite element model of boss clamping for milling of thin-walled blank is constructed. The finite element model of boss clamping for milling of thin-walled blank includes a thin-walled blank unit and a boss unit. The thin-walled blank unit includes a milled unit and a part unit.

[0076] The milling depth is used as the grid size in the depth direction, the milling width is used as the grid size in the width direction, and the milling cutter advance distance is used as the grid size in the milling cutter advance direction. According to the determined grid size, the thin-walled blank unit in the finite element model of the milling boss clamping of the thin-walled blank is meshed;

[0077] According to the solution accuracy requirements, the thin-walled blank unit in the finite element model of the thin-walled blank milling boss clamping is divided into several layers along the thickness direction through mesh division;

[0078] The initial residual stress applied to each thin-walled blank element is determined based on the initial residual stress data.

[0079] Among them, the finite element mesh discretization needs to determine the model unit division size according to the tool and milling processing parameters. The specific mesh size in the depth direction is equal to the milling depth a p , the grid size in the width direction is equal to the milling width a e In order to save calculation time, the feed step grid division strategy is adopted to simplify the material removal process. The main idea is to complete the material removal amount of multiple single-tooth feeds as one analysis step in the finite element simulation. The grid size along the milling cutter forward direction is equal to the milling cutter forward distance d of each feed step. w Or its factor. In the simulation software, the initial residual stress of each layer of the finite element model blank is set by defining the field module.

[0080] Further, in step 4, a milling tool path is selected, and based on the milling tool path, the milling force is gradually applied to the milled unit of the milling boss clamping finite element model of the thin-walled blank according to the milling tool advance distance, so as to simulate the milling process and obtain the processing deformation data and residual stress data, which specifically include:

[0081] Select the milling path;

[0082] According to the milling parameters, the milling cutter advance distance and milling force are calculated respectively, among which,

[0083] The distance the milling cutter advances in each feed step is:

[0084]

[0085] Among them, d w is the distance the milling cutter moves forward, R is the radius of the milling cutter, a e is the milling width;

[0086] The milling force is:

[0087]

[0088] F i ∈(F x , F y , F z )

[0089] Among them, F i is the milling force, is the milling force coefficient determined by the processing material and milling conditions, n is the milling speed, a p is the milling depth, is the exponential coefficient corresponding to the milling speed n, is the milling depth a p The corresponding exponential coefficient, m Fi The distance d that the milling cutter advances w The corresponding exponential coefficient is, is the exponential coefficient corresponding to the milling cutter radius R;

[0090] Based on the milling tool path, the milling force is gradually applied to the milled unit of the milling boss clamping finite element model of the thin-walled blank according to the milling cutter advance distance, so as to simulate the milling process and obtain the machining deformation data and residual stress data.

[0091] In a preferred embodiment of the present application, the milling tool path is one of transverse sequential milling, longitudinal sequential milling, transverse S-shaped milling, longitudinal S-shaped milling, spiral milling from outside to inside, and spiral milling from inside to outside.

[0092] The various milling parameters in the milling force calculation formula are determined based on milling test measurements, and the milling force is calculated based on the formula.

[0093] After obtaining the milling path, cutter advance distance, and milling force, the milling process is simulated. Specifically, the milling force is gradually applied to the milled unit according to the milling cutter advance distance. Then, the unit stiffness is multiplied by a minimum amount (10e -6) is reduced to achieve the effect of unit removal, and the load, mass, strain and specific heat of the removed unit tend to zero; finally, the milling force at that position is unloaded, and the milling force is applied to the next unit to be milled, and this process is repeated until all the units that need to be milled are removed, thus realizing the simulation of the milling process.

[0094] In the present application, the preferred method for the clamping layout of the thin-walled structure milling boss considering the tool path is as follows: in step 5, after completing the milling deformation calculation of all test schemes, the range analysis method is used to evaluate the influence of the preferred factors on the technical indicators, and the better scheme is finally selected through comparison, which specifically includes:

[0095] Determine the technical indicators for the optimal boss clamping layout, including maximum machining deformation, average machining deformation, and maximum residual stress;

[0096] Determine the value of technical indicators based on processing deformation data and residual stress data;

[0097] Calculate the average value of a technical indicator:

[0098]

[0099] in, is the average technical index of the vth optimal factor pair at the uth level, K uv is the technical indicator of the uth level and the vth optimal factor pair, h v is the number of levels of the vth preferred factor;

[0100] Calculate the range of a technical indicator:

[0101]

[0102] Among them, R v is the extreme difference of technical indicators. for The maximum value of for The minimum value of

[0103] According to the extreme difference of technical indicators, the boss clamping layout scheme that meets the requirements is screened out.

[0104] The larger the range, the more important the optimization factor is. Conversely, the smaller the range, the less important the optimization factor is. Therefore, according to the size of the range, the priority of the optimization factor to the technical indicator can be evaluated, and the optimal boss clamping layout solution for the technical indicator can be selected.

[0105] Similarly, evaluate the influence of each optimization factor on different technical indicators, and determine the optimal boss clamping layout scheme corresponding to each technical indicator. Finally, compare the various boss clamping layout schemes, further optimize them by the size of the extreme difference, and determine the optimal boss clamping layout scheme. If the scheme does not exist in the orthogonal table, select a better scheme or reset the research scheme.

[0106] In one embodiment of the present application, a milling boss clamping layout scheme is optimized for a square 7050 aluminum alloy flat thin-walled part, and the specific process is as follows:

[0107] A. According to the orthogonal test principle, the optimal factors for thin-walled structure milling are determined, including the number of bosses, boss position, boss width, and boss thickness. The number of levels corresponding to each optimal factor is 3. The number of bosses is set to 1, 2, and 3 on each side, for a total of 4, 8, and 12. The level table of orthogonal test factors is shown in Table 1. On this basis, a typical L9(3 4 ) The orthogonal table of boss clamping layout scheme is shown in Table 2.

[0108] Table 1

[0109]

[0110]

[0111] Table 2

[0112]

[0113] B. Create a finite element model of the quenched thin-walled blank in the finite element software, specify the material's physical properties that change nonlinearly with temperature and the high-temperature mechanical properties, select specific process measures for solution quenching, establish a finite element model of the thin-walled blank, apply boundary conditions based on the actual clamping situation, process the workpiece to 600 degrees and maintain it, then cool it naturally in the air, and calculate the residual stress field caused by uneven temperature changes.

[0114] C. Figure 2 As shown, a 1:1 blank model is created in the finite element software according to the blank structural part with a length of 100 mm, a width of 100 mm, and a thickness of 6 mm. Based on the test plan of the orthogonal test planning, a process boss is added to the blank model to create a thin-walled blank geometric model with a process boss.

[0115] Apply the boundary conditions of local displacement, and determine the model unit division size according to the milling cutter and milling processing parameters. The specific grid size in the depth direction is equal to the milling depth of 2mm, the grid size in the width direction is equal to the milling width of 2mm, and the radius R of the milling cutter is 4mm. The distance the milling cutter advances in each feed step can be calculated as Complete the creation of the finite element model of the thin-walled blank with process bosses.

[0116] According to the required solution accuracy, the workpiece is divided into three layers along the thickness direction through mesh division. According to the results of the residual stress simulation analysis obtained in B, the surface residual stress of the blank is obtained. In the simulation software, the initial residual stress of each layer of the finite element model blank with boss is set by defining the field module.

[0117] D. Determine the appropriate milling force calculation formula based on the actual tool and process, and determine the milling parameters in the milling force calculation formula based on milling test measurements. In this embodiment, the milling force is F x =160N, F y =180N, F z =90N.

[0118] like Figure 3 Among the six typical milling tool path solutions shown, the sequential milling path-1 is selected as the milling tool path in this embodiment.

[0119] At each time step, the milling force is applied to the milled unit in turn, and the unit stiffness is reduced in turn to remove the unit, simulating the milling process. In this embodiment, the milling removal thickness is 2 mm. The unit being milled is multiplied by the reduction factor (10e -6 ), the load, mass, strain and specific heat of the removed unit all tend to zero. The schematic diagram of unit removal and milling force application process is shown in Figure 4 shown.

[0120] E. Determine the main technical indicators for the optimization of thin-walled structure milling bosses, including: maximum machining deformation, average machining deformation, maximum residual stress, etc. Taking the maximum machining deformation index as an example, the maximum deformation under each working condition under the sequential milling tool path is calculated as shown in Table 3.

[0121] Table 3

[0122] 1 2 3 4 5 6 7 8 9 Maximum deformation / mm 0.29 0.25 0.24 0.26 0.22 0.21 0.15 0.13 0.12

[0123] The range analysis method is used to evaluate the influence of the determined optimization factors on the maximum processing deformation, and the best solution is finally selected through comparison.

[0124] Calculate the average value of the technical indicators, and calculate the range based on the average value of the technical indicators;

[0125] The larger the range, the more important the preferred factor is. Conversely, the smaller the range, the less important the factor is. In this embodiment, the number of factors is 4, the level number is 3, and the calculated index values ​​and range values ​​are shown in Table 4. According to the calculation results, among all the schemes set in this embodiment, when there are 12 process bosses, the boss width is 6 mm, the boss spacing is 4 mm, and the boss thickness is 2 mm, the maximum deformation is the smallest.

[0126] Table 4

[0127] Very bad Number of bosses N Boss width W Boss distance D Boss thickness H <![CDATA[K 1v ]]> 0.26 0.23 0.21 0.21 <![CDATA[K 2v ]]> 0.23 0.20 0.21 0.20 <![CDATA[K 3v ]]> 0.13 0.19 0.20 0.21 <![CDATA[R v ]]> 0.13 0.04 0.01 0.01

[0128] Similarly, the above steps are repeated to evaluate the influence of various influencing factors and levels on the average processing deformation and the maximum residual stress. Finally, the optimal solution of this embodiment is 12 process bosses, with a boss width of 6 mm, a boss spacing of 4 mm, and a boss thickness of 2 mm.

[0129] The present application proposes a method for optimizing the clamping layout of thin-walled milling bosses by considering the tool path. First, an optimal solution for the boss clamping layout is designed by an orthogonal test method, and a milling tool path is assumed in a relatively weak area of ​​the workpiece. Secondly, based on the finite element method and unit stiffness reduction technology, the effects of different tool paths and clamping layouts on processing indicators are comprehensively considered. Finally, the range method is used to comprehensively evaluate multiple technical indicators and optimize the optimal boss layout solution. The present application has the following beneficial effects:

[0130] (1) Fast calculation based on the finite element method and reduction of calculation conditions through orthogonal experiments can effectively reduce the user's time cost and material cost of boss design.

[0131] (2) The coupling effect of tool path and process boss layout on workpiece machining deformation can be considered and comprehensive optimization can be performed.

[0132] (3) The influence of maximum deformation, average deformation and residual stress can be systematically considered, and the influence of various factors and levels on the main indicators can be quantitatively analyzed.

[0133] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for optimizing the clamping layout of a thin-walled structure milling boss considering the tool path, characterized in that: include: Step 1: Obtain various boss clamping layout solutions; Step 2: construct a finite element model of the thin-walled blank and perform finite element calculation to obtain initial residual stress data; Step 3, constructing a finite element model of the milling boss clamping of a thin-walled blank according to different boss clamping layout schemes, determining a grid size according to milling parameters, and meshing the finite element model of the milling boss clamping of the thin-walled blank according to the grid size, and applying the initial residual stress data to the finite element model of the milling boss clamping of the thin-walled blank; Step 4: Select a milling tool path, and based on the milling tool path, gradually apply the milling force to the milled unit of the milling boss clamping finite element model of the thin-walled blank according to the milling tool path according to the milling cutter advance distance, so as to simulate the milling process and obtain machining deformation data and residual stress data; Step 5: Determine the optimal technical indicators of the boss clamping layout scheme, and screen out the boss clamping layout scheme that meets the requirements based on the technical indicators, the processing deformation data and the residual stress data.

2. The method for optimizing the clamping layout of the thin-walled structure milling boss considering the tool path according to claim 1, characterized in that: In step 1, obtain various boss clamping layout solutions, including: Determine the optimal factors of boss clamping layout scheme that affect the milling deformation of thin-walled structures, and construct the optimal factor table; Determine the level number corresponding to each of the preferred factors; Based on the orthogonal test principle, an orthogonal table of boss clamping layout schemes is constructed to obtain a variety of boss clamping layout schemes.

3. The method for optimizing the clamping layout of the thin-walled structure milling boss considering the tool path according to claim 2, characterized in that: The preferred factors include the number of bosses, boss positions and boss sizes.

4. The method for optimizing the clamping layout of the thin-walled structure milling boss considering the tool path according to claim 3 is characterized in that: In step 2, a finite element model of the thin-walled blank is constructed, and finite element calculation is performed to obtain initial residual stress data, including: The sequential coupling method is used to perform finite element simulation on the blank, determine the material's nonlinear physical properties and high-temperature mechanical properties with temperature, determine the solution quenching process, and construct a finite element model of the thin-walled blank; Boundary conditions are applied to the finite element model of the thin-walled blank, and a temperature load is applied to the finite element model of the thin-walled blank, and finite element calculation is performed to obtain initial residual stress data.

5. The method for optimizing the clamping layout of the thin-walled structure milling boss considering the tool path according to claim 4, characterized in that: In step three, a finite element model of a milling boss clamping of a thin-walled blank is constructed according to different boss clamping layout schemes, a grid size is determined according to milling parameters, and the finite element model of the milling boss clamping of the thin-walled blank is meshed according to the grid size, and the initial residual stress data is applied to the finite element model of the milling boss clamping of the thin-walled blank, including: Constructing a finite element model of a milling boss clamping of a thin-walled blank according to different boss clamping layout schemes, wherein the finite element model of a milling boss clamping of a thin-walled blank comprises a thin-walled blank unit and a boss unit, and the thin-walled blank unit comprises a milled unit and a part unit; The milling depth is used as the grid size in the depth direction, the milling width is used as the grid size in the width direction, and the milling cutter advance distance is used as the grid size in the milling cutter advance direction, and the thin-walled blank unit in the finite element model of the thin-walled blank milling boss clamping is meshed according to the determined grid size; According to the solution accuracy requirement, the thin-walled blank unit in the thin-walled blank milling boss clamping finite element model is divided into several layers along the thickness direction by meshing; The initial residual stress applied to each layer of the thin-walled blank unit is determined according to the initial residual stress data.

6. The method for optimizing the clamping layout of the thin-walled structure milling boss considering the tool path according to claim 5, characterized in that: In step 4, a milling tool path is selected, and based on the milling tool path, a milling force is gradually applied to the milled unit of the milling boss clamping finite element model of the thin-walled blank according to the milling tool advance distance, so as to simulate the milling process and obtain machining deformation data and residual stress data, including: Select the milling path; According to the milling parameters, the milling cutter advance distance and milling force are calculated respectively, among which, The distance the milling cutter advances in each feed step is: Among them, d w is the distance the milling cutter moves forward, R is the radius of the milling cutter, a e is the milling width; The milling force is: F i ∈(F x ,F y ,F z ) Among them, F i is the milling force, is the milling force coefficient, n is the milling speed, a p is the milling depth, is the exponential coefficient corresponding to the milling speed n, is the milling depth a p The corresponding exponential coefficient is, The distance d that the milling cutter advances w The corresponding exponential coefficient is, is the exponential coefficient corresponding to the milling cutter radius R; Based on the milling tool path, the milling force is gradually applied to the milled unit of the thin-walled blank milling boss clamping finite element model according to the milling cutter advance distance, so as to simulate the milling process and obtain machining deformation data and residual stress data.

7. The method for optimizing the clamping layout of the thin-walled structure milling boss considering the tool path according to claim 6, characterized in that: The milling tool path is one of transverse sequential milling, longitudinal sequential milling, transverse S-shaped milling, longitudinal S-shaped milling, spiral milling from outside to inside, and spiral milling from inside to outside.

8. The method for optimizing the clamping layout of the boss for milling of thin-walled structures considering the tool path according to claim 7, characterized in that: In step 5, the preferred technical indicators of the boss clamping layout scheme are determined, and the boss clamping layout scheme that meets the requirements is screened out according to the technical indicators, the processing deformation data and the residual stress data, including: Determine the technical indicators for the optimal boss clamping layout scheme; Determining the value of the technical indicator according to the processing deformation data and the residual stress data; Calculate the average value of a technical indicator: in, is the average technical index of the vth optimal factor pair at the uth level, K uv is the technical indicator of the uth level and the vth optimal factor pair, h v is the number of levels of the vth preferred factor; Calculate the range of a technical indicator: Among them, R v is the extreme difference of technical indicators. for The maximum value of for The minimum value of According to the extreme difference of technical indicators, the boss clamping layout scheme that meets the requirements is screened out.

9. The method for optimizing the clamping layout of the boss for milling of thin-walled structures considering the tool path according to claim 8, characterized in that: The technical indicators include maximum machining deformation, average machining deformation, and maximum residual stress.

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