Method for calculating time-varying kinetic parameters of curved-surface thin-wall part facing side milling machining

Abstract

The invention relates to the technical field of kinetic parameter identification of a thin-walled workpiece machining system, and provides a method for calculating time-varying kinetic parameters of a curved-surface thin-walled workpiece for side milling machining, which comprises the following steps of: 1, importing a workpiece model, and carrying out different treatments on a matrix and a material removal body; 2, importing a cutter location data file of which the axial cutting depth is equal to the height of the suspended wall of the curved-surface thin wall; step 3, creating a finite element grid fused with cutter location information; step 4, respectively defining local coordinate systems on all nodes of the bottom edge L15 of the material removal body, wherein the local coordinate systems are used for rapidly judging the removed material grid; 5, changing the material attribute of the material removal body so as to simulate the material cutting process of the workpiece; step 6, carrying out modal analysis on the curved surface thin wall at any cutter position by using a block Lansosas method; and 7, extracting a modal frequency and a vibration mode for forecasting the processing stability. According to the method, the kinetic parameters required by the curved-surface thin-wall part side milling stability forecasting program can be more conveniently obtained.

Description

Technical Field

[0001] The invention relates to the field of dynamic parameter identification of thin-walled parts processing systems, and in particular to a method for calculating time-varying dynamic parameters of curved surface thin-walled parts for side milling processing. Background Art

[0002] Identifying the dynamic parameters of thin-walled parts during side milling is beneficial to obtaining the structural time-varying vibration characteristics of thin-walled parts as material is removed. It can help process personnel determine the natural frequency and modal vibration shape of the workpiece at each tool position during the processing, and then optimize the process dynamically to avoid chatter. At present, the dynamic parameter identification of thin-walled parts during processing is mainly achieved through experimental testing and finite element numerical calculation.

[0003] The experimental test method based on force hammer tapping has been widely used due to its advantages of simple modeling and convenient execution, and has become a very mature method for structural dynamics parameter identification. However, the use of experimental test methods to identify the modal parameters of thin-walled parts during the cutting process requires the use of force hammer tapping experiments at a large number of tool positions, so the machine tool must be repeatedly started and stopped, which not only consumes a lot of time, but also makes it difficult to guarantee the accuracy of the tapping position, that is, the vibration mode acquisition position. Especially for thin-walled parts with more complex curved surfaces, it is obviously not the best choice to obtain the modal parameters of the processing process based solely on experimental test methods.

[0004] Reference 1 "Tuysuz, O.; Altintas, Y. Frequency Domain Updating of Thin-Walled Workpiece Dynamics Using Reduced Order Substructuring Method in Machining. J. Manuf. Sci. Eng. 2017, 139, 071013." uses a computationally efficient reduced-order dynamic substructure method to decompose a large structural system into smaller subsystems to simplify the problem, and adds virtual substructures with opposite dynamics to eliminate the influence of the removed material on the workpiece dynamics, thereby more quickly solving the dynamic parameters of the thin-walled workpiece during machining. The invention patent application number 201810376359.7 discloses a method for quickly obtaining the dynamic parameters of a workpiece during milling. The method mainly obtains the time-varying dynamic parameters of the workpiece by reducing the degree of freedom and reducing the dimension of the matrix, and can quickly obtain the dynamic parameters of the workpiece.

[0005] The above literature and patents focus on the structural characteristics and material properties of the parts themselves, and improve the calculation efficiency of dynamic parameters in the finite element modal analysis process, but do not consider the path information of the machining tool and cannot directly output the dynamic parameters at the specified tool position. Therefore, it is still necessary to rely on the traditional method of traversing nearby nodes and weighted calculation of vibration mode values ​​to obtain more accurate dynamic parameters. Summary of the invention

[0006] The present invention mainly solves the technical problem that the dynamic parameters of curved thin-walled parts considering the material removal effect are difficult to extract in the prior art, and proposes a method for calculating the time-varying dynamic parameters of curved thin-walled parts for side milling, so as to more conveniently obtain the dynamic parameters required by the side milling stability prediction program of curved thin-walled parts, specifically including the multi-contact point modal vibration mode and natural frequency at the contact position between the curved thin-walled part and the tool.

[0007] The present invention provides a method for calculating time-varying dynamic parameters of a curved thin-walled part for side milling, comprising the following steps:

[0008] Step 1: Import the workpiece model and perform different processing on the base body V1 and the material removal body V2;

[0009] The workpiece model is divided into a base body V1 and a material removal body V2; the upper surface of the base body V1 is represented by A1, the lower surface of the base body is represented by A2, the right surface of the base body is represented by A3, and the left surface of the base body is represented by A4. The 12 edges of the base body V1 are represented by L1-L12 respectively. Specifically, the left side of the base bottom surface is the first edge represented by L1, the lower side of the front of the base body is the second edge represented by L2, the lower side of the back of the base body is the third edge represented by L3, and the right side of the base bottom surface is the fourth edge represented by L4. Indicated by, the fifth edge on the front of the substrate is indicated by L5, the sixth edge on the rear of the substrate is indicated by L6, the seventh edge on the right side of the substrate is indicated by L7, the eighth edge on the left side of the substrate is indicated by L8, the ninth edge on the right side of the rear of the substrate is indicated by L9, the tenth edge on the right side of the front of the substrate is indicated by L10, the eleventh edge on the left side of the front of the substrate is indicated by L11, the twelfth edge on the left side of the rear of the substrate is indicated by L12, and the contact surface on the substrate V1 with the material removal body V2 is indicated by A5;

[0010] The upper surface of the material removal body of the material removal body V2 is represented by A7, the lower surface of the material removal body is represented by A8, the right surface of the material removal body is represented by A9, the left surface of the material removal body is represented by A10, and the 12 edges of the material removal body V2 are represented by L13-L24 respectively. Specifically, the thirteenth edge is represented by L13 on the right side of the rear of the material removal body, the fourteenth edge is represented by L14 on the upper side of the rear of the material removal body, the fifteenth edge is represented by L15 on the lower side of the rear of the material removal body, the sixteenth edge is represented by L16 on the left side of the rear of the material removal body, and the seventeenth edge is represented by L17 on the upper side of the front of the material removal body. The eighteenth edge at the bottom of the front of the material removal body is indicated by L18, the nineteenth edge at the right of the front of the material removal body is indicated by L19, the twentieth edge at the left of the front of the material removal body is indicated by L20, the twenty-first edge at the left of the bottom of the material removal body is indicated by L21, the twenty-second edge at the left of the top of the material removal body is indicated by L22, the twenty-third edge at the right of the top of the material removal body is indicated by L23, the twenty-fourth edge at the right of the bottom of the material removal body is indicated by L24, the contact surface of the material removal body V2 with the base V1 is indicated by A11, A11 is also used as the machined inner surface of the material removal body V2, and A12 is the machined outer surface;

[0011] Step 2: Import the axial cutting depth a p The tool position data file is equal to the height h of the curved thin wall overhang;

[0012] Step 3: Based on the tool position data file imported in step 2, project to the machined inner surface A11 and the machined outer surface A12 of the material removal volume V2, and control the position of the node to be generated by creating projection points, so as to create a finite element mesh integrating the tool position information;

[0013] Step 4, define local coordinate systems on all nodes of the bottom edge L15 of the material removal volume V2 for fast determination of the removed material mesh;

[0014] Step 5, changing the material properties of the material removal volume V2 to simulate the workpiece material cutting process;

[0015] Step 6: Constrain the degrees of freedom of all nodes at the bottom of the thin wall surface, and use the block Lanczos method to constrain the arbitrary tool position CL x Modal analysis of curved thin walls;

[0016] Step 7: extract the modal frequency and vibration mode, wherein the vibration mode is the vibration mode of the finite element node contained in the contact line with the tool, which is used for machining stability prediction.

[0017] Furthermore, the step 1 includes the following steps 101 to 104:

[0018] Step 101, importing a workpiece model;

[0019] Step 102, defining the uncut material properties and the removed chip material properties; wherein M1 represents the uncut material properties and M2 represents the removed chip material properties, assigning the base V1 and the material removal volume V2 a three-dimensional solid unit type, and before the workpiece material is removed, specifying the material properties of the base V1 and the material removal volume V2 as M1;

[0020] Step 103, meshing the base body V1 and the material removal body V2 using a finite element preprocessor;

[0021] Step 104 , after recording the unit information of the material removal volume V2 mesh into the material removal volume node number file, the material removal volume V2 mesh is deleted.

[0022] Furthermore, in step 103, the grid division method is:

[0023] Base body V1: the second edge L2, the third edge L3, the fifth edge L5, and the sixth edge L6 are equally divided into m+1 parts, the first edge L1, the seventh edge L7, the fourth edge L4, and the eighth edge L8 are equally divided into n parts, and the ninth edge L9, the tenth edge L10, the eleventh edge L11, and the twelfth edge L12 are equally divided into l parts;

[0024] Material removal body V2: the fourteenth edge L14, the fifteenth edge L15, the seventeenth edge L17, and the eighteenth edge L18 are equally divided into m+1 parts, the thirteenth edge L13, the sixteenth edge L16, the nineteenth edge L19, and the twentieth edge L20 are equally divided into n parts, and the twenty-first edge L21, the twenty-second edge L22, the twenty-third edge L23, and the twenty-fourth edge L24 are divided into 1 part.

[0025] Furthermore, the step 3 includes the following steps 301 to 304:

[0026] Step 301, creating projection points on the inner and outer surfaces of the processing;

[0027] a) For machining the outer surface A12, at any tool position i (1≤i≤m), the tool tip is projected onto the fifteenth edge L15, and the projection point is recorded as P i ;

[0028] b) P i As the starting point, with dz = h / n as the step length, select a point along the tool axis vector direction at tool position i;

[0029] c) Project all the points onto the machined inner surface A11 to form a series of projection points, where the position of the last projection point is determined by the point projected onto the seventeenth edge L17;

[0030] Repeat steps a) to c) to create a projection point matrix that integrates the tool position information on the entire machining outer surface A12. Similarly, create such a projection point matrix on the machining inner surface A11.

[0031] Step 302, extracting the coordinates of all key points, including the coordinates of all vertices of the material removal volume V2, the coordinates of points taken at the left and right edges of the machined inner surface A11 and the machined outer surface A12 with a step length of dz=h / n, and the coordinates of all projection points in step 301;

[0032] Step 303, assigning the coordinates of all key points in step 301 to the corresponding V2 mesh unit nodes described in the material removal volume node number file in step 104, and regenerating the material removal volume V2 mesh;

[0033] Step 304 , define the surface A5 of the base body V1 as the target surface unit, select the nodes on the mesh of the machined inner surface A11 of the material removal body V2 as the contact surface unit, and perform point-surface binding processing on the two.

[0034] Furthermore, the step 5 includes the following steps 501 to 502:

[0035] Step 501: For any tool position CL during side milling x , in all local coordinate systems defined by step 4 that the tool passes through, a column of nodes in the Z direction is selected by setting the X direction search range [-x0, +x0];

[0036] Step 502: Create a node set for all selected nodes, and modify the material properties of the units connected to all nodes in the node set to M2, simulating any tool position CL x Material removal below.

[0037] The present invention provides a method for calculating time-varying dynamic parameters of curved thin-walled parts for side milling. First, the model of the material to be processed is imported, and it is meshed according to the tool position data, and the material matrix and the material removal body are bound. Then, the local coordinate system is established in sequence according to the bottom node information of the mesh division, and the material properties of the workpiece model removal body are changed to simulate material removal. Finally, the bottom of the material is fixed, and then a modal analysis is performed to obtain the dynamic parameters required by the stability prediction program for side milling of curved thin-walled parts. The method combines the tool axis information with the finite element mesh information, specifically, the mesh nodes of the workpiece division at the tool position are perfectly overlapped with the contact points between the tool and the workpiece, which is more conducive to extracting the dynamic parameters required by the stability prediction program. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart for realizing a method for calculating time-varying dynamic parameters of a curved thin-walled part for side milling provided by the present invention;

[0039] Figure 2 is a schematic diagram of the surface of the substrate V1 of the present invention;

[0040] Figure 3 is a schematic diagram of the surface of the material removal body V2 of the present invention;

[0041] Figure 4a -d is the upper, lower, left and right sides of the local material removal body V2 of the present invention;

[0042] Figure 5 It is a schematic diagram of the model after the material processing of the present invention is completed. DETAILED DESCRIPTION

[0043] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all the contents.

[0044] like Figure 1 As shown, an embodiment of the present invention provides a method for calculating time-varying dynamic parameters of a curved thin-walled part for side milling. Taking the side milling process of a curved thin-walled part as an example, the method includes the following steps:

[0045] Step 1: import the workpiece model, and perform different processing on the base body V1 and the material removal body V2, including the following steps 101 to 104:

[0046] Step 101: Import the workpiece model.

[0047] like Figure 2 As shown, the workpiece model is divided into a substrate V1 and a material removal body V2. The upper surface of the substrate V1 is represented by A1, the lower surface of the substrate is represented by A2, the right surface of the substrate is represented by A3, and the left surface of the substrate is represented by A4. The 12 edges of the substrate V1 are represented by L1-L12 respectively. Specifically, the left side of the substrate bottom surface is the first edge represented by L1, the lower side of the front of the substrate is the second edge represented by L2, the lower side of the back of the substrate is the third edge represented by L3, and the right side of the substrate bottom surface is the fourth edge represented by L 4, the fifth edge is represented by L5 on the upper front of the substrate, the sixth edge is represented by L6 on the upper rear of the substrate, the seventh edge is represented by L7 on the right side of the substrate, the eighth edge is represented by L8 on the left side of the substrate, the ninth edge is represented by L9 on the right side of the rear of the substrate, the tenth edge is represented by L10 on the right side of the front of the substrate, the eleventh edge is represented by L11 on the left side of the front of the substrate, the twelfth edge is represented by L12 on the left side of the rear of the substrate, and the contact surface on the substrate V1 with the material removal body V2 is represented by A5.

[0048] like Figure 3 , Figure 4a -d, the upper surface of the material removal body of the material removal body V2 is represented by A7, the lower surface of the material removal body is represented by A8, the right surface of the material removal body is represented by A9, the left surface of the material removal body is represented by A10, and the 12 edges of the material removal body V2 are represented by L13-L24 respectively. Specifically, the thirteenth edge is represented by L13 on the right side of the rear of the material removal body, the fourteenth edge is represented by L14 on the upper side of the rear of the material removal body, the fifteenth edge is represented by L15 on the lower side of the rear of the material removal body, the sixteenth edge is represented by L16 on the left side of the rear of the material removal body, and the seventeenth edge is represented by L17 on the upper side of the front of the material removal body. The eighteenth edge is represented by L18 at the bottom of the front of the material removal body, the nineteenth edge is represented by L19 at the right side of the front of the material removal body, the twentieth edge is represented by L20 at the left side of the front of the material removal body, the twenty-first edge is represented by L21 on the left side of the bottom of the material removal body, the twenty-second edge is represented by L22 on the left side of the top of the material removal body, the twenty-third edge is represented by L23 on the right side of the top of the material removal body, and the twenty-fourth edge is represented by L24 on the right side of the bottom of the material removal body. The contact surface of the material removal body V2 with the base V1 is represented by A11, and A11 also serves as the machined inner surface of the material removal body V2, and A12 is the machined outer surface.

[0049] Step 102: Define the properties of the uncut material and the properties of the cut chip material

[0050] Among them, M1 represents the uncut material properties and M2 represents the removed chip material properties. The matrix V1 and the material removal body V2 are assigned a three-dimensional solid unit type. Before the workpiece material is removed, the material properties of the matrix V1 and the material removal body V2 are specified to be M1.

[0051] Step 103: Use a finite element preprocessor to perform mesh division on the base body V1 and the material removal body V2.

[0052] The method of sowing seeds on the edges is as follows: the base V1: the second edge L2, the third edge L3, the fifth edge L5, and the sixth edge L6 are equally divided into m+1 parts, the first edge L1, the seventh edge L7, the fourth edge L4, and the eighth edge L8 are equally divided into n parts, and the ninth edge L9, the tenth edge L10, the eleventh edge L11, and the twelfth edge L12 are equally divided into l parts;

[0053] Material removal body V2: the fourteenth edge L14, the fifteenth edge L15, the seventeenth edge L17, and the eighteenth edge L18 are equally divided into m+1 parts, the thirteenth edge L13, the sixteenth edge L16, the nineteenth edge L19, and the twentieth edge L20 are equally divided into n parts, and the twenty-first edge L21, the twenty-second edge L22, the twenty-third edge L23, and the twenty-fourth edge L24 are divided into 1 part.

[0054] Step 104 , after recording the unit information of the material removal volume V2 mesh (including all unit numbers and the node numbers contained therein) into the material removal volume node number file, the material removal volume V2 mesh is deleted.

[0055] There are 9 columns in the file, the first column stores the unit number, and the 2nd to 9th columns store the node numbers.

[0056] Step 2: Import the axial cutting depth a p The tool position data file is equal to the height h of the curved thin wall overhang.

[0057] The tool position data file uses array AA with an array dimension of m×6, where the number of rows m represents the number of tool positions; 6 is the number of columns, the first three columns represent the position coordinates of the tool tip point, and the last three columns represent the tool axis vector.

[0058] Step 3: Based on the tool position data file imported in step 2, project to the machined inner surface A11 and the machined outer surface A12 of the material removal volume V2, and control the position of the nodes to be generated by creating projection points, so as to create a finite element mesh integrating the tool position information. Step 3 includes the following steps 301 to 304:

[0059] Step 301: Create projection points on the inner and outer surfaces of the machined parts:

[0060] a) For machining the outer surface A12, at any tool position i (1≤i≤m), the tool tip is projected onto the fifteenth edge L15, and the projection point is recorded as P i ;

[0061] b) P i As the starting point, with dz = h / n as the step length, select a point along the tool axis vector direction at tool position i;

[0062] c) Project all the points onto the machined inner surface A11 to form a series of projection points, where the position of the last projection point is determined by the point projected onto the seventeenth edge L17;

[0063] Repeat steps a) to c) to create a projection point matrix that integrates the tool position information on the entire processed outer surface A12. Similarly, create such a projection point matrix on the processed inner surface A11.

[0064] Step 302 , extract the coordinates of all key points, including the coordinates of all vertices of the material removal volume V2 , the coordinates of points taken with a step size of dz=h / n on the left and right edges of the machined inner surface A11 and the machined outer surface A12 , and the coordinates of all projection points in step 301 .

[0065] The number of key point coordinates is equal to the number of mesh unit nodes of the material removal volume V2 in step 103 .

[0066] Step 303: assign the coordinates of all key points in step 301 to the corresponding V2 mesh unit nodes described in the material removal volume node number file in step 104, and regenerate the material removal volume V2 mesh.

[0067] Step 304 , define the surface A5 of the base body V1 as the target surface unit, select the nodes on the mesh of the machined inner surface A11 of the material removal body V2 as the contact surface unit, and perform point-surface binding processing on the two.

[0068] Step 4: Define local coordinate systems on all nodes of the bottom edge L15 of the material removal volume V2 for fast determination of the removed material mesh.

[0069] Among them, the Z axis of the local coordinate system is determined by the tool axis vector, the X axis is determined by the feed direction of the tool, and the Y axis is determined by the cross product of the Z axis and the X axis.

[0070] Step 5: Change the material properties of the material removal volume V2 to simulate the workpiece material cutting process. Step 5 includes the following steps 501 to 502:

[0071] Step 501: For any tool position CL during side milling x In all local coordinate systems defined by step 4 that the tool passes through, a column of nodes in the Z direction is selected by setting the X direction search range to [-x0, +x0].

[0072] Step 502: Create a node set for all selected nodes, and modify the material properties of the units connected to all nodes in the node set to M2, simulating any tool position CL x The following material removal. Figure 5 As shown, this is a schematic diagram of the model after material processing and removal.

[0073] Step 6: Constrain the degrees of freedom of all nodes at the bottom of the thin wall surface, and use the block Lanczos method to constrain the arbitrary tool position CL x Modal analysis of curved thin walls.

[0074] Step 7: extract the modal frequency and vibration mode, wherein the vibration mode is the vibration mode of the finite element node contained in the contact line with the tool, which is used for machining stability prediction.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that modifying the technical solutions described in the aforementioned embodiments, or replacing some or all of the technical features therein by equivalents, does not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating time-varying dynamic parameters of curved thin-walled parts for side milling, characterized in that: The following steps are involved: Step 1: Import the workpiece model and perform different processing on the base body V1 and the material removal body V2; The workpiece model is divided into a base body V1 and a material removal body V2; the upper surface of the base body V1 is represented by A1, the lower surface of the base body is represented by A2, the right surface of the base body is represented by A3, and the left surface of the base body is represented by A4. The 12 edges of the base body V1 are represented by L1-L12 respectively. Specifically, the left side of the base bottom surface is the first edge represented by L1, the lower side of the front of the base body is the second edge represented by L2, the lower side of the back of the base body is the third edge represented by L3, and the right side of the base bottom surface is the fourth edge represented by L4. Indicated by, the fifth edge on the front of the substrate is indicated by L5, the sixth edge on the rear of the substrate is indicated by L6, the seventh edge on the right side of the substrate is indicated by L7, the eighth edge on the left side of the substrate is indicated by L8, the ninth edge on the right side of the rear of the substrate is indicated by L9, the tenth edge on the right side of the front of the substrate is indicated by L10, the eleventh edge on the left side of the front of the substrate is indicated by L11, the twelfth edge on the left side of the rear of the substrate is indicated by L12, and the contact surface on the substrate V1 with the material removal body V2 is indicated by A5; The upper surface of the material removal body of the material removal body V2 is represented by A7, the lower surface of the material removal body is represented by A8, the right surface of the material removal body is represented by A9, the left surface of the material removal body is represented by A10, and the 12 edges of the material removal body V2 are represented by L13-L24 respectively. Specifically, the thirteenth edge is represented by L13 on the right side of the rear of the material removal body, the fourteenth edge is represented by L14 on the upper side of the rear of the material removal body, the fifteenth edge is represented by L15 on the lower side of the rear of the material removal body, the sixteenth edge is represented by L16 on the left side of the rear of the material removal body, and the seventeenth edge is represented by L17 on the upper side of the front of the material removal body. The eighteenth edge at the bottom of the front of the material removal body is indicated by L18, the nineteenth edge at the right of the front of the material removal body is indicated by L19, the twentieth edge at the left of the front of the material removal body is indicated by L20, the twenty-first edge at the left of the bottom of the material removal body is indicated by L21, the twenty-second edge at the left of the top of the material removal body is indicated by L22, the twenty-third edge at the right of the top of the material removal body is indicated by L23, the twenty-fourth edge at the right of the bottom of the material removal body is indicated by L24, the contact surface of the material removal body V2 with the base V1 is indicated by A11, A11 is also used as the machined inner surface of the material removal body V2, and A12 is the machined outer surface; Step 2: Import the axial cutting depth a p The tool position data file is equal to the height h of the curved thin wall overhang; Step 3: Based on the tool position data file imported in step 2, project to the machined inner surface A11 and the machined outer surface A12 of the material removal volume V2, and control the position of the node to be generated by creating projection points, so as to create a finite element mesh integrating the tool position information; Step 4, define local coordinate systems on all nodes of the bottom edge L15 of the material removal volume V2 for fast determination of the removed material mesh; Step 5, changing the material properties of the material removal volume V2 to simulate the workpiece material cutting process; Step 6: Constrain the degrees of freedom of all nodes at the bottom of the thin wall surface, and use the block Lanczos method to constrain the arbitrary tool position CL x Modal analysis of curved thin walls; Step 7: extract the modal frequency and vibration mode, wherein the vibration mode is the vibration mode of the finite element node contained in the contact line with the tool, which is used for machining stability prediction.

2. The method for calculating time-varying dynamic parameters of curved thin-walled parts for side milling according to claim 1 is characterized in that: The step 1 includes the following steps 101 to 104: Step 101, importing a workpiece model; Step 102, defining the uncut material properties and the removed chip material properties; wherein M1 represents the uncut material properties and M2 represents the removed chip material properties, assigning the base V1 and the material removal volume V2 a three-dimensional solid unit type, and before the workpiece material is removed, specifying the material properties of the base V1 and the material removal volume V2 as M1; Step 103, meshing the base body V1 and the material removal body V2 using a finite element preprocessor; Step 104 , after recording the unit information of the material removal volume V2 mesh into the material removal volume node number file, the material removal volume V2 mesh is deleted.

3. The method for calculating time-varying dynamic parameters of curved thin-walled parts for side milling according to claim 2 is characterized in that: In step 103, the grid is divided in the following way: Base body V1: the second edge L2, the third edge L3, the fifth edge L5, and the sixth edge L6 are equally divided into m+1 parts, the first edge L1, the seventh edge L7, the fourth edge L4, and the eighth edge L8 are equally divided into n parts, and the ninth edge L9, the tenth edge L10, the eleventh edge L11, and the twelfth edge L12 are equally divided into l parts; Material removal body V2: the fourteenth edge L14, the fifteenth edge L15, the seventeenth edge L17, and the eighteenth edge L18 are equally divided into m+1 parts, the thirteenth edge L13, the sixteenth edge L16, the nineteenth edge L19, and the twentieth edge L20 are equally divided into n parts, and the twenty-first edge L21, the twenty-second edge L22, the twenty-third edge L23, and the twenty-fourth edge L24 are divided into 1 part.

4. The method for calculating time-varying dynamic parameters of curved thin-walled parts for side milling according to claim 3 is characterized in that: The step 3 includes the following steps 301 to 304: Step 301, creating projection points on the inner and outer surfaces of the processing; a) For machining the outer surface A12, at any tool position i (1≤i≤m), the tool tip is projected onto the fifteenth edge L15, and the projection point is recorded as P i ; b) P i As the starting point, with dz = h / n as the step length, select a point along the tool axis vector direction at tool position i; c) Project all the points onto the inner surface A11 to form a series of projection points, where the position of the last projection point is determined by the point projected onto the seventeenth edge L17; Repeat steps a) to c) to create a projection point matrix that integrates the tool position information on the entire machining outer surface A12. Similarly, create such a projection point matrix on the machining inner surface A11. Step 302, extracting the coordinates of all key points, including the coordinates of all vertices of the material removal volume V2, the coordinates of points taken at the left and right edges of the machined inner surface A11 and the machined outer surface A12 with a step length of dz=h / n, and the coordinates of all projection points in step 301; Step 303, assigning the coordinates of all key points in step 301 to the corresponding V2 mesh unit nodes described in the material removal volume node number file in step 104, and regenerating the material removal volume V2 mesh; Step 304 , define the surface A5 of the base body V1 as the target surface unit, select the nodes on the mesh of the machined inner surface A11 of the material removal body V2 as the contact surface unit, and perform point-surface binding processing on the two.

5. The method for calculating time-varying dynamic parameters of curved thin-walled parts for side milling according to claim 4 is characterized in that: The step 5 includes the following steps 501 to 502: Step 501: For any tool position CL during side milling x , in all local coordinate systems defined by step 4 that the tool passes through, a column of nodes in the Z direction is selected by setting the X direction search range [-x0, +x0]; Step 502: Create a node set for all selected nodes, and modify the material properties of the units connected to all nodes in the node set to M2, simulating any tool position CL x Material removal below.

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