A method for obtaining optimal machining parameters of a cantilever part based on numerical simulation

Abstract

This invention proposes a method for obtaining optimal machining parameters for cantilever parts based on numerical simulation. The method uses Advantedge FEM software to solve for cutting force and cutting temperature under different machining parameters. The cutting force is then input as a boundary condition into finite element software such as ANSYS Workbench / ABAQUS. Through static strength analysis, modal analysis, and harmonic response analysis, the machining deformation, natural frequencies, and vibration amplitude of the cantilever part under different machining parameters are simulated. By combining the two numerical simulation software programs, accurate prediction of cutting force, cutting temperature, cutting deformation, and part vibration frequency during machining is achieved. Based on the prediction results, the optimal cutting parameters and clamping methods for machining large cantilever parts can be determined, providing guidance for actual production and effectively improving machining quality and efficiency while reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of numerical simulation of metal cutting processes, and in particular to a method for obtaining optimal machining parameters for cantilever parts based on numerical simulation. Background Technology

[0002] In the field of aerospace equipment, the wide variety of aerospace parts, their complex shapes, and diverse materials make machining deformation a particularly prominent issue. For example, large cantilever parts, due to their poor rigidity, are prone to deformation and localized chatter during machining, affecting dimensional accuracy and surface quality. Furthermore, high-strength materials such as titanium alloys, due to their inherent properties, present numerous challenges, including difficulty in machining, high cutting temperatures, and chatter. Deformation and improved machining accuracy are typically controlled by adjusting machining parameters.

[0003] Currently, machining parameters for parts are mainly determined by experience. Furthermore, factors such as cutting force, cutting temperature, cutting deformation, and vibration frequency cannot be directly obtained during machining and can only be improved through iterative optimization using an "experiment-correction" method. This approach not only fails to obtain optimal machining parameters but also consumes significant time and resources, severely delaying parts production cycles.

[0004] Invention patent CN114595614A provides a simulation method for controlling the deformation of frame-type workpieces during machining. It obtains the initial residual stress field through a finite element model and establishes an orthogonal table based on pre-determined levels of factors affecting machining deformation. Simulation machining is then performed, yielding multiple simulation results. Finally, based on these results, the grooving method, grooving size, and machining sequence corresponding to the minimum deformation are determined. However, this method only simulates the residual stress field after machining. Factors such as cutting force, cutting temperature, and cutting chatter all cause machining deformation in frame-type workpieces. Furthermore, different clamping methods also have a certain impact on machining deformation, and this method does not comprehensively consider the influence of machining parameters.

[0005] Invention patent CN108182325B provides a method for predicting and analyzing deformation during machining of thin-walled structural parts. The stress distribution of the structure after rough machining, obtained through finite element analysis, is used as the initial stress for finish machining analysis. The residual stress distribution on the surface of the finished structural part is then solved through theoretical modeling to simulate the final machining deformation. This method controls machining deformation by iterating the stress throughout the entire machining process, from rough to finish, and also considers the effect of cutting force coupling. However, it does not consider different clamping methods or cutting chatter.

[0006] Invention patent CN111390299B provides a method for predicting the deformation during the machining of floating support friction plates. It simulates the temperature, stress, and deformation distributions during machining by setting cutting parameters using finite element software, thus achieving the prediction of machining deformation. However, like the previous two patents, it does not consider the clamping method and cutting chatter in the machining deformation calculation, leading to inaccurate simulation results. Summary of the Invention

[0007] In view of the above technical problems, this invention proposes a method for obtaining the optimal machining parameters of cantilever parts based on numerical simulation. The numerical simulation comprehensively considers the influence of factors such as temperature field, cutting force, clamping method, and cutting chatter on the deformation of the machined parts. The obtained optimal machining parameters have a good guiding role in actual production, which can improve the machining quality of parts and save production costs.

[0008] To address the aforementioned problems, this invention proposes a numerical simulation method for controlling the machining deformation of large cantilever parts, which includes the following steps:

[0009] A method for obtaining optimal machining parameters for cantilever parts based on numerical simulation, characterized by the following steps:

[0010] Step 1: Use Advantedge FEM software to perform numerical simulation iteration on the 3D model of the cantilever part to obtain the optimal temperature field and optimal cutting force of the cantilever part, and determine the optimal cutting speed, optimal feed rate and optimal depth of cut based on the optimal temperature field and optimal cutting force.

[0011] Step 2: Using the optimal cutting force obtained in Step 1 as the boundary condition, perform static strength analysis on the three-dimensional model of the cantilever part using finite element software to obtain the machining deformation of the part under different clamping methods.

[0012] Step 3: Use finite element software to perform modal analysis on the three-dimensional model of the cantilever part, obtain the first six natural frequencies and the first six mode shapes of the part, and thus determine the weak areas of specific stiffness under different clamping methods.

[0013] Step 4, Optimal cutting speed verification:

[0014] Using the first six natural frequencies and first six mode shapes obtained in step three as boundary conditions, the three-dimensional model of the cantilever part was analyzed for harmonic response using finite element software to obtain the deformation response frequency of the part. The corresponding spindle speed n was then calculated based on this deformation response frequency. The optimal cutting speed obtained in step one was then verified based on this spindle speed n. The verification results showed that the optimal cutting speed would not cause the part to resonate and deform.

[0015] Step 5: Determine the optimal processing parameters:

[0016] The optimal cutting speed, optimal feed rate, and optimal depth of cut of the cantilever part obtained in step one are output as the optimal cutting parameters.

[0017] Based on the machining deformation of the parts under different clamping methods obtained in step two, select the clamping method with the smallest machining deformation. Based on this clamping method, determine whether to add support to the weaker specific stiffness area under the different clamping methods determined in step three according to the machining deformation requirements, thereby determining the optimal clamping method.

[0018] The optimal cutting parameters and optimal clamping method are used as the output of the optimal machining parameters.

[0019] Furthermore, step one specifically includes:

[0020] Step 1.1 Boundary condition settings:

[0021] The established 3D model of the cantilever part is imported into Advantedge FEM software in ".stp" format. Boundary conditions are set based on the Johnson-Cook constitutive model in Advantedge FEM software, including part material properties, part size, cutting layer thickness, tool basic size, tool material properties and coating thickness, main cutting parameters, tool-part friction coefficient, and coolant flow rate; the main cutting parameters include cutting speed, feed rate, and depth of cut.

[0022] Step 1.2: Mesh the tool and part;

[0023] Step 1.3 Submit the simulation task to obtain the temperature field cloud map and cutting force variation curve under the current cutting parameters;

[0024] Step 1.4 Change one or more of the three parameters in the boundary conditions: cutting speed, feed rate, and depth of cut. Repeat steps 1.1-1.3 to perform numerical simulation until the optimal temperature field and optimal cutting force of the cantilever part are obtained. Take the set of cutting speed, feed rate, and depth of cut with the minimum maximum cutting temperature value and the minimum maximum cutting force value as the optimal cutting speed, optimal feed rate, and optimal depth of cut for the current process.

[0025] Furthermore, in step 1.2, the local mesh is refined for the parts involved in the cutting process, while the default global mesh size is used for the remaining parts.

[0026] Furthermore, the finite element software mentioned in steps two, three, and four is ABAQUS software.

[0027] Furthermore, the finite element software mentioned in steps two, three, and four is ANSYS Workbench software.

[0028] Furthermore, step two specifically involves:

[0029] Step 2.1 Import the 3D model of the cantilever part into ANSYS Workbench software in ".stp" format;

[0030] Step 2.2 Call the Static Structural module in ANSYS Workbench software. Apply constraints at different positions to the three-dimensional model of the cantilever part in the Static Structural module to simulate different clamping methods of the workpiece. Input the optimal cutting force obtained in Step 1.4 into the boundary conditions to obtain the deformation cloud map of the cutting surface of the part under different clamping methods. Based on the deformation cloud map of the cutting surface of the part, determine the machining deformation of the part under different clamping methods.

[0031] Furthermore, step three specifically involves: calling the Modal module in the ANSYS Workbench software, performing modal analysis on the part in the Modal module, determining the natural frequencies and the first six mode shapes of the part under different clamping methods, and determining the specific stiffness weak areas under different clamping methods based on the natural frequencies and the first six static models.

[0032] Furthermore, step four specifically involves:

[0033] The Harmonic Response module in ANSYS Workbench software is called to perform harmonic response analysis on the part. The first six natural frequencies and the first six mode shapes obtained by modal analysis in step three, as well as the optimal cutting force applied to the part, are used as boundary conditions to obtain the vibration amplitude curve. Based on the vibration amplitude curve, the deformation response frequency of the part is obtained through harmonic response analysis.

[0034] Based on the deformation response frequency, the machine tool spindle speed n is calculated. The machine tool spindle speed n is compared and verified with the optimal cutting speed obtained in step one. The optimal cutting speed is not equal to the machine tool spindle speed n, nor is it near the machine tool spindle speed, and will not cause resonance during part processing.

[0035] The beneficial effects of this invention are:

[0036] This invention simulates the machining deformation of cantilever parts using multiple numerical simulation software programs. Specifically, Advantedge FEM software is used to solve for cutting forces and cutting temperatures under different machining parameters. The cutting forces are then input as boundary conditions into finite element software such as ANSYS Workbench / ABAQUS. Through static strength analysis, modal analysis, and harmonic response analysis, the machining deformation, natural frequencies, and vibration amplitude of the cantilever parts under different machining parameters are simulated. By combining two numerical simulation software programs, accurate predictions of cutting forces, cutting temperatures, cutting deformation, and part vibration frequencies during machining are achieved. Based on the prediction results, the optimal cutting parameters and clamping methods can be determined when machining large cantilever parts, effectively reducing machining deformation. Therefore, the numerical simulation results obtained by this invention have certain guiding significance for actual production, effectively improving machining quality and efficiency, and reducing production costs. Attached Figure Description

[0037] Figure 1 This is a flowchart of the present invention.

[0038] Figure 2 This is the mesh generation diagram for the tool-part combination.

[0039] Figure 3 This is a temperature field contour map of the cutting process.

[0040] Figure 4 This is the curve showing the change in cutting force.

[0041] Figure 4 In this context, Force-X, Force-Y, and Force-Z refer to the cutting forces in the X, Y, and Z directions, respectively, under the currently set cutting coordinates.

[0042] Figure 5 This is a contour map of the deformation of the cut surface of the cantilever component.

[0043] Figure 6 This is the vibration amplitude curve. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0045] Example:

[0046] This embodiment is implemented based on actual production and processing, and on the premise of the technical solution of this invention. Figure 1 The flowchart shown below illustrates the present invention, providing detailed implementation methods and specific operation procedures, as follows:

[0047] Step 1: Use the Advantedge FEM software to solve for the optimal cutting force and optimal cutting parameters of the cantilever part. The specific method is as follows:

[0048] 1.1 Boundary condition settings:

[0049] The established 3D model of the cantilever part is imported into Advantedge FEM software in ".stp" format. Boundary conditions are set based on the Johnson-Cook constitutive model in Advantedge FEM software, including part material properties, part size, cutting layer thickness, tool basic size, tool material properties and coating thickness, main cutting parameters, tool-part friction coefficient, and coolant flow rate; the main cutting parameters include cutting speed, feed rate, and depth of cut.

[0050] 1.2 Mesh generation for tools and parts:

[0051] like Figure 2 As shown, the tool and part are meshed. To improve computational efficiency and the accuracy of simulation results, this invention refines the local mesh of the parts involved in the cutting process (that is, makes the mesh of the parts involved in the cutting process denser), while using the default global mesh size for the remaining parts.

[0052] 1.3 Obtain the temperature field contour plot and cutting force variation curve under the current cutting parameters:

[0053] like Figure 3 , 4 As shown, after adding boundary conditions and meshing, submitting the simulation task will yield the temperature field contour map under the current cutting parameters (e.g., ...). Figure 3 (as shown) and the cutting force variation curve (as shown) Figure 4 (as shown);

[0054] Through such Figure 3 The temperature field cloud map shown reveals the region of highest temperature occurrence under the current cutting parameters. Because some materials are high-temperature resistant, their hardness and strength change with varying cutting parameters, thus affecting the cutting force. Simultaneously, cutting temperature also affects the tool's wear resistance. In actual machining, high-temperature machining should be avoided as much as possible.

[0055] Since the cutting process itself is a non-steady-state change, therefore Figure 4 The X, Y, Z curves show an upward and downward fluctuating trend, based on... Figure 4 The X, Y, Z curves can be used to obtain the maximum values ​​of the cutting forces in the X, Y, and Z directions;

[0056] 1.4 Through multiple iterations, the optimal temperature field and optimal cutting force are obtained, and the optimal cutting parameters are determined based on the optimal temperature field and optimal cutting force:

[0057] Cutting speed, feed rate, and depth of cut are the three key elements of metal cutting. For each cutting operation, there is a series of empirical data for these three elements. Based on this series of empirical data, we change one or more of the three parameters in the boundary conditions—cutting speed, feed rate, and depth of cut—and repeat steps 1.1-1.3 to perform numerical simulations until the optimal temperature field and optimal cutting force of the cantilever part are obtained. The set of cutting speed, feed rate, and depth of cut that minimizes the highest cutting temperature and the maximum cutting force is taken as the optimal cutting parameters for the current operation. The aforementioned "series of empirical data" can be selected based on the approximate range of the three cutting elements given by machine tool and cutting tool distributors for cutting a certain metal (aluminum alloy, titanium alloy, high-temperature alloy), or based on the approximate range of the three cutting elements for typical structures (thin-walled parts, cantilever parts, etc.) given in relevant books or papers.

[0058] Step two: Use the Static Structural module in ANSYS Workbench software to solve for the machining deformation of the part under different clamping methods. The specific method is as follows:

[0059] 2.1 Import the 3D model of the cantilever part into ANSYS Workbench software in ".stp" format;

[0060] 2.2 Call the Static Structural module in ANSYS Workbench software. Apply constraints at different positions to the 3D model of the cantilever part in the Static Structural module to simulate different clamping methods of the workpiece. Input the optimal cutting force obtained in step 1.4 into the boundary conditions (the boundary conditions are not the same as the boundary conditions set in step 1.1 above. It can be understood that the optimal cutting force output in step 1 is used as the current input condition). Obtain the deformation cloud map of the cutting surface of the part under different clamping methods (each clamping method will obtain a deformation cloud map of the cutting surface of the part). Based on the deformation cloud map of the cutting surface of the part, the machining deformation of the part under different clamping methods can be determined. Figure 5 The image shown is an example of a deformation contour plot of a part's cutting surface under a certain clamping method. Figure 5 As shown, under a certain clamping method, the maximum machining deformation of the part is 0.027 mm.

[0061] Step 3: Use the Modal module in ANSYS Workbench software to solve for the first six natural frequencies and first six mode shapes of the part, thereby determining the specific stiffness weak areas under different clamping methods. The specific method is as follows:

[0062] The Modal module in ANSYS Workbench software is called to perform modal analysis on the part, determining the natural frequencies and the first six mode shapes of the part under different clamping methods. Different clamping methods can be regarded as different workpiece-fixture systems. The higher the values ​​of the first six natural frequencies, the more stable the workpiece-fixture system. Based on the natural frequencies and the first six static models, the specific stiffness weak areas under different clamping methods can be determined. If there are strict requirements for the machining deformation of the specific stiffness weak areas, supports can be added to these specific stiffness weak areas during actual cutting to reduce machining deformation.

[0063] Step four: Use the Harmonic Response module in ANSYS Workbench software to solve the deformation response of the part at the cutting frequency. Based on this, verify the optimal cutting speed obtained in step one. The specific method is as follows:

[0064] The Harmonic Response module in ANSYS Workbench software is called to perform harmonic response analysis on the part. The first six natural frequencies and mode shapes obtained from the modal analysis in step three, along with the optimal cutting force applied to the part, are used as boundary conditions (these boundary conditions are not the same as those set in 1.1 and 2.2; they can be understood as using the first six natural frequencies and mode shapes output from step three, along with the optimal cutting force output from step one, as the current input conditions). The result is as follows: Figure 6 The vibration amplitude curve shown is used to determine the deformation response frequency of the part through harmonic response analysis. During actual machining, the tool should be avoided cutting the part at this deformation response frequency to prevent resonance deformation. Figure 6 The figure shows an example of vibration amplitude curve. It can be seen from the figure that when the tool cuts the part at 270HZ, it will resonate with the part and deform, with a vibration amplitude of 0.35776mm.

[0065] The method to avoid cutting parts by the tool at the deformation response frequency is as follows:

[0066] According to the formula f = n·z / 60, where n is the machine tool spindle speed, z is the number of teeth of the tool used, and f is the vibration frequency; substituting the deformation response frequency f obtained based on the vibration amplitude curve into the formula f = n·z / 60, the spindle speed n at this time is calculated. Then, the obtained spindle speed n is compared with the cutting speed in the optimal cutting parameters iterated in step 1.4 above.

[0067] If the slope at the peak (i.e., the deformation response frequency) of the vibration amplitude curve is very large, then it is only necessary to check whether the cutting speed in the selected optimal cutting parameters is equal to the spindle speed n.

[0068] If the slope of the peak value (i.e., the deformation response frequency) on the vibration amplitude curve is small and shows a slow upward trend, it is also necessary to check whether the cutting speed in the selected optimal cutting parameters is near the spindle speed n (a difference within ±10% can be considered as being near it).

[0069] If so, cutting at this speed should be avoided.

[0070] The purpose of this step is to double-verify the optimal cutting speed obtained in step 1.4 above through the vibration amplitude curve. Extensive practical verification results show that the optimal cutting speed iterated in step 1.4 above is not equal to the machine tool spindle speed n, nor is it near the machine tool spindle speed n, and will not cause resonance during part machining.

[0071] Step 5: Determine the optimal processing parameters. The specific method is as follows:

[0072] The optimal cutting parameters of the cantilever part obtained in step one, including the optimal cutting speed, optimal feed rate, and optimal depth of cut, are output as the optimal cutting parameters for the current process.

[0073] Based on the machining deformation of the parts under different clamping methods obtained in step two, select the clamping method with the smallest machining deformation. Based on this clamping method, determine whether to add support to the weaker specific stiffness area under the different clamping methods determined in step three according to the machining deformation requirements, thereby determining the optimal clamping method.

[0074] Using the optimal cutting parameters and optimal clamping method as optimal machining parameters to guide actual cutting can effectively reduce machining deformation of parts.

[0075] Finally, it should be noted that steps two, three, and four above are not limited to being implemented in ANSYS Workbench software. In other embodiments, steps two, three, and four above can also be performed in other finite element software such as ABAQUS, that is, static strength analysis, modal analysis, and harmonic response analysis of the parts can be performed using other finite element software such as ABAQUS.

Claims

1. A method for obtaining optimal machining parameters for cantilever parts based on numerical simulation, characterized in that, Includes the following steps: Step 1: Use Advantedge FEM software to perform numerical simulation iteration on the 3D model of the cantilever part to obtain the optimal temperature field and optimal cutting force of the cantilever part, and determine the optimal cutting speed, optimal feed rate and optimal depth of cut based on the optimal temperature field and optimal cutting force. Step 2: Using the optimal cutting force obtained in Step 1 as the boundary condition, perform static strength analysis on the three-dimensional model of the cantilever part using finite element software to obtain the machining deformation of the part under different clamping methods. Step 3: Use finite element software to perform modal analysis on the three-dimensional model of the cantilever part, obtain the first six natural frequencies and the first six mode shapes of the part, and thus determine the weak areas of specific stiffness under different clamping methods. Step 4, Optimal cutting speed verification: Using the first six natural frequencies and first six mode shapes obtained in step three as boundary conditions, the three-dimensional model of the cantilever part was analyzed for harmonic response using finite element software to obtain the deformation response frequency of the part. The corresponding spindle speed n was then calculated based on this deformation response frequency. The optimal cutting speed obtained in step one was then verified based on this spindle speed n. The verification results showed that the optimal cutting speed would not cause the part to resonate and deform. Step 5: Determine the optimal processing parameters: The optimal cutting speed, optimal feed rate, and optimal depth of cut of the cantilever part obtained in step one are output as the optimal cutting parameters. Based on the machining deformation of the parts under different clamping methods obtained in step two, select the clamping method with the smallest machining deformation. Based on this clamping method, determine whether to add support to the weaker specific stiffness area under the different clamping methods determined in step three according to the machining deformation requirements, thereby determining the optimal clamping method. The optimal cutting parameters and optimal clamping method are used as the output of the optimal machining parameters.

2. The method for obtaining optimal machining parameters of a cantilevered part based on numerical simulation according to claim 1, wherein: Step one specifically involves: Step 1.1 Boundary condition settings: The established 3D model of the cantilever part is imported into Advantedge FEM software in ".stp" format. Boundary conditions are set based on the Johnson-Cook constitutive model in Advantedge FEM software, including part material properties, part size, cutting layer thickness, tool basic size, tool material properties and coating thickness, main cutting parameters, tool-part friction coefficient, and coolant flow rate; the main cutting parameters include cutting speed, feed rate, and depth of cut. Step 1.2: Mesh the tool and part; Step 1.3 Submit the simulation task to obtain the temperature field cloud map and cutting force variation curve under the current cutting parameters; Step 1.4 Change one or more of the three parameters in the boundary conditions: cutting speed, feed rate, and depth of cut. Repeat steps 1.1-1.3 to perform numerical simulation until the optimal temperature field and optimal cutting force of the cantilever part are obtained. Take the set of cutting speed, feed rate, and depth of cut with the minimum maximum cutting temperature value and the minimum maximum cutting force value as the optimal cutting speed, optimal feed rate, and optimal depth of cut for the current process.

3. The method of claim 2, wherein: In step 1.2, the local mesh is refined for the parts involved in the cutting process, while the default global mesh size is used for the remaining parts.

4. The method for obtaining optimal machining parameters of a cantilevered part based on numerical simulation according to claim 1 or 2 or 3, characterized in that: The finite element software mentioned in steps two, three, and four is ABAQUS software.

5. The method for obtaining optimal machining parameters for cantilever parts based on numerical simulation according to claim 1, 2, or 3, characterized in that: The finite element software mentioned in steps two, three, and four is ANSYS Workbench software.

6. The method for obtaining optimal machining parameters for cantilever parts based on numerical simulation according to claim 5, characterized in that: Step two specifically involves: Step 2.1 Import the 3D model of the cantilever part into ANSYS Workbench software in ".stp" format; Step 2.2 Call the Static Structural module in ANSYS Workbench software. Apply constraints at different positions to the three-dimensional model of the cantilever part in the Static Structural module to simulate different clamping methods of the workpiece. Input the optimal cutting force obtained in Step 1.4 into the boundary conditions to obtain the deformation cloud map of the cutting surface of the part under different clamping methods. Based on the deformation cloud map of the cutting surface of the part, determine the machining deformation of the part under different clamping methods.

7. The method of claim 6, wherein: Step three specifically involves: calling the Modal module in the ANSYS Workbench software, performing modal analysis on the part in the Modal module, determining the natural frequency and the first six mode shapes of the part under different clamping methods, and determining the specific stiffness weak areas under different clamping methods based on the natural frequency and the first six static models.

8. The method of claim 7, wherein: Step four specifically involves: The Harmonic Response module in ANSYS Workbench software is called to perform harmonic response analysis on the part. The first six natural frequencies and the first six mode shapes obtained by modal analysis in step three, as well as the optimal cutting force applied to the part, are used as boundary conditions to obtain the vibration amplitude curve. Based on the vibration amplitude curve, the deformation response frequency of the part is obtained through harmonic response analysis. Based on the deformation response frequency, the machine tool spindle speed n is calculated. The machine tool spindle speed n is compared and verified with the optimal cutting speed obtained in step one. The optimal cutting speed is not equal to the machine tool spindle speed n, nor is it near the machine tool spindle speed, and will not cause resonance during part processing. If the optimal cutting speed differs from the machine tool spindle speed within ±10%, it is considered that the optimal cutting speed is near the machine tool spindle speed.

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