A processing method and a processing system for reducing roughness of an inner hole

Abstract

The application relates to a processing method and a processing system for reducing the roughness of an inner hole, and the processing method comprises the following steps: S1, establishing a finite element model of contact between a rolling tool and a workpiece, wherein the rolling tool is provided with a roller, and the workpiece is provided with an inner hole; S2, performing a first simulation experiment to simulate the simulation roughness of the hole wall of the inner hole under different combinations of different interference amounts and different chamfer radii of the roller; S3, performing an offline experiment to measure the actual roughness of the hole wall of the inner hole of the workpiece under different combinations of different interference amounts and different chamfer radii of the roller, and the parameters of different interference amounts and different chamfer radii correspond to the same during the first simulation experiment and the offline experiment; S4, optimizing the finite element model based on the simulation roughness and the actual roughness; and S5, performing a second simulation experiment to simulate the simulation roughness of the hole wall of the inner hole under different combinations of different interference amounts and different chamfer radii of the roller.

Description

Technical Field

[0001] This application relates to the field of internal hole finishing technology, and in particular to a machining method and system for reducing the roughness of internal holes. Background Technology

[0002] Internal hole rolling is a plastic processing method that uses a high-hardness and smooth roller to roll into contact with a metal surface, causing localized micro-plastic deformation of the surface layer, thereby improving the surface roughness. At the same time, it can also change the metallographic structure of the surface layer of the part, which is beneficial to the distribution of residual stress, increases the hardness of the metal surface layer, and thus improves the mechanical properties and service life of the part.

[0003] For aluminum alloy roll forming, excessive interference can damage the machined surface and significantly reduce fatigue life. Therefore, the interference in aluminum alloy roll forming should be kept below 0.16 mm. A smaller interference means that the changes in grain refinement and residual compressive stress are not significant. Therefore, the roll forming strengthening of aluminum alloys mainly improves fatigue life by improving surface roughness, making surface roughness an important indicator for evaluating the quality of roll forming strengthening.

[0004] In traditional internal hole rolling processes, rolling quality optimization only focuses on the impact of experimental parameters (such as interference fit and feed rate) on roughness, neglecting the feasible path of optimizing the rolling tool structure by changing the chamfer radius of the roller. Moreover, traditional methods do not fully consider the coupling relationship between the chamfer radius and contact stress and material plastic deformation, making it difficult to achieve directional optimization of roughness through parameter adjustment. Summary of the Invention

[0005] Therefore, it is necessary to provide a machining method and system for reducing the roughness of internal holes, addressing the problems of low roughness control accuracy and blind parameter optimization in traditional processes.

[0006] This application provides a machining method for reducing the roughness of internal holes, the machining method for reducing the roughness of internal holes includes:

[0007] S1. Establish a finite element model of the contact between the rolling cutter and the workpiece, wherein the rolling cutter is provided with rollers and the workpiece is provided with an inner hole;

[0008] S2. Conduct the first simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference fit and different chamfer radii of the roller;

[0009] S3. Conduct offline experiments to measure the actual roughness of the inner hole wall of the workpiece under different combinations of interference fit and different chamfer radii of the roller, and the parameters of different interference fit and different chamfer radii of the roller are the same when conducting the first simulation experiment and the offline experiment.

[0010] S4. Optimize the finite element model based on the simulated roughness and the actual roughness;

[0011] S5. Conduct a second simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference and different chamfer radii of the roller, so as to obtain the optimal chamfer radius and optimal interference corresponding to the minimum roughness. The parameter scale value of the second simulation experiment is smaller than the parameter scale value of the first simulation experiment.

[0012] S6. Based on the optimal chamfer radius, manufacture the chamfer radius of the roller, and adjust the depth of the roller burnishing tool pressed into the hole wall during actual machining based on the optimal interference fit.

[0013] In one embodiment, step M is included before step S6:

[0014] Based on the data from the first simulation experiment and the offline experiment, a multiple regression model was established for roughness, chamfer radius, and interference fit:

[0015] Where Ra is the roughness, r is the chamfer radius, and δ is the interference fit;

[0016] By solving for the extreme points using partial derivatives, the optimal chamfer radius and optimal interference corresponding to the minimum roughness can be determined.

[0017] Determine the difference between the optimal chamfer radius and optimal interference calculated by the multiple regression model and the optimal chamfer radius and optimal interference obtained in the second simulation experiment. If the difference is within the preset difference range, proceed to step S6.

[0018] In one embodiment, step S1 includes:

[0019] A three-dimensional model of a workpiece with an internal hole is established, the material parameters of the workpiece are defined, and the elastic-plastic deformation relationship is established through the JC constitutive equation.

[0020] A three-dimensional model of the roller rolling tool is established, the maximum diameter of the roller is defined, and the chamfer radius of the roller is set with multiple parameters.

[0021] The interference fit between the rolling tool and the workpiece is set by multiple parameters;

[0022] Through formula R 滚刀 =δ+R 孔 Calculate the maximum radius of the rolling cutter, where R 滚刀 R is the maximum radius of the rolling tool, δ is the interference, and R is the maximum radius of the rolling tool. 孔 The radius of the inner hole is denoted as .

[0023] In one embodiment, step S4 further includes step S41:

[0024] If the error between the actual roughness and the simulated roughness is greater than a preset value, the JC constitutive equation of the material is corrected, and the strain rate sensitivity coefficient of the JC constitutive equation of the material is adjusted.

[0025] In one embodiment, when adjusting the strain rate sensitivity coefficient, the scale value of each adjustment is 0.001, the roughness error under multiple strain rate sensitivity coefficients is calculated, and the strain rate sensitivity coefficient under the minimum roughness error is set as the final strain rate sensitivity coefficient.

[0026] In one embodiment, establishing a three-dimensional model of a workpiece with an inner hole includes: setting the mesh size of the inner hole wall to a first mesh value;

[0027] Step S4 further includes step S42: determining whether the first grid value setting is reasonable. If the roughness simulation value changes by less than 5% after reducing the first grid value, it is determined that the first grid value setting is reasonable; if the roughness simulation value changes by more than or equal to 5%, it is determined that the first grid value setting is unreasonable, and the grid size is adjusted.

[0028] In one embodiment, the interference fit parameter is set in the range of 0.1mm-0.16mm;

[0029] In the first simulation experiment, the scale division of the interference fit was 0.02 mm;

[0030] In the second simulation experiment, the scale division of the interference fit was 0.01 mm.

[0031] This application also provides a processing system, including:

[0032] A roller burnishing tool, comprising: a mandrel, a protective sleeve, and rollers; the mandrel being connected to a machine tool spindle; the protective sleeve being fitted onto the mandrel and having a mounting groove; the rollers being disposed within the mounting groove and capable of rotating relative to the mandrel, and having a chamfered structure on the side of the rollers facing away from the machine tool spindle;

[0033] A controller, communicatively connected to the rolling cutter, controls the rolling cutter to process the inner hole of the workpiece according to the machining method for reducing the roughness of the inner hole as described above.

[0034] In one embodiment, the mandrel includes a first segment and a second segment connected to each other, and the protective sleeve is fitted onto the first segment;

[0035] The rolling cutter further includes an adjustment component, which includes:

[0036] A thrust bearing is sleeved on the second section and abuts against the end face of the protective sleeve;

[0037] An adjusting sleeve is fitted onto the protective sleeve, the thrust bearing, and the second section, and is threadedly connected to the second section.

[0038] An elastic element is fitted onto the protective sleeve and disposed within the adjusting sleeve, with its two ends respectively abutting against the inner wall of the adjusting sleeve and the end face of the thrust bearing.

[0039] In one embodiment, the rolling tool further includes a clamping shank connected to the mandrel, the mandrel being connected to the machine tool spindle via the clamping shank.

[0040] The aforementioned machining method for reducing the roughness of the inner hole involves first conducting a simulation experiment to measure the simulated roughness using a finite element model of the contact between the roller and the workpiece. This is combined with offline experiments to measure the actual roughness, achieving a precise mapping of the multi-physics field of the rolling process. After optimizing and correcting the finite element model based on the data from the first simulation and offline experiments, a second simulation experiment is conducted using finer parameter division values, covering more chamfer radii and interference combinations. Finally, the chamfer structure of the roller is manufactured based on the optimal chamfer radius determined in the second simulation experiment. The cutting depth of the rolling tool is dynamically adjusted based on the optimal interference, resulting in a uniform distribution of contact stress between the bottom chamfer of the roller and the inner hole wall. This synergistically suppresses microcracks caused by excessive local plastic deformation, further reducing the roughness of the inner hole. Attached Figure Description

[0041] Figure 1 A flowchart illustrating a processing method for reducing the roughness of internal holes provided in an embodiment of this application.

[0042] Figure 2 A flowchart of step M provided for an embodiment of this application.

[0043] Figure 3 This is a schematic diagram of the processing system provided in an embodiment of this application.

[0044] Figure 4 This is a cross-sectional view of the rolling tool provided in an embodiment of this application.

[0045] Figure 5 This is a schematic diagram of the structure of the roller provided in an embodiment of this application.

[0046] Figure 6 for Figure 5 A magnified view of a portion at point A.

[0047] Figure label:

[0048] 100. Workpiece;

[0049] 200. Roller burnishing tool; 210. Mandrel; 220. Protective sleeve; 230. Roller; 231. Chamfering structure; 240. Adjusting assembly; 241. Thrust bearing; 242. Adjusting sleeve; 243. Elastic element; 250. Clamping handle;

[0050] 300. Fixtures;

[0051] 400. Installation platform. Detailed Implementation

[0052] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0053] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0054] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0055] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0056] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0057] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0058] This application provides a machining method for reducing the roughness of internal holes, such as... Figure 1 As shown, the machining methods for reducing the roughness of internal holes include:

[0059] S1. Establish a finite element model of the contact between the rolling cutter 200 and the workpiece 100, wherein the rolling cutter 200 is provided with rollers 230 and the workpiece 100 is provided with an inner hole.

[0060] S2. Conduct the first simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference fit and different chamfer radii of roller 230.

[0061] S3. Conduct offline experiments to measure the actual roughness of the inner hole wall of workpiece 100 under different combinations of interference fit and different chamfer radii of roller 230. In the first simulation experiment and offline experiment, the parameters of different interference fit and different chamfer radii of roller 230 are the same.

[0062] S4. Optimize the finite element model based on the simulated roughness and the actual roughness;

[0063] S5. Conduct a second simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference and different chamfer radii of roller 230, so as to obtain the optimal chamfer radius and optimal interference corresponding to the minimum roughness. The parameter scale value of the second simulation experiment is smaller than that of the first simulation experiment.

[0064] S6. Based on the optimal chamfer radius, manufacture the chamfer radius of the roller 230, and adjust the depth of the rolling cutter 200 pressed into the hole wall during actual machining based on the optimal interference.

[0065] The above-mentioned machining method for reducing the roughness of the inner hole involves establishing a finite element model of the contact between the roller 230 and the workpiece 100, conducting a first simulation experiment to measure the simulated roughness, and combining this with an offline experiment to measure the actual roughness corresponding to the parameters of the first simulation experiment, thus achieving a precise mapping of the multi-physics field of the rolling process. After optimizing and correcting the finite element model based on the relevant data from the first simulation experiment and the offline experiment, a second simulation experiment is conducted using more refined parameter scale values, covering more chamfer radius and interference combination. Finally, the chamfer structure 231 of the roller 230 is manufactured according to the optimal chamfer radius determined in the second simulation experiment, and the pressing depth of the rolling tool 200 is dynamically adjusted based on the optimal interference, so that the contact stress distribution between the bottom chamfer of the roller 230 and the hole wall of the inner hole is uniform, which synergistically suppresses microcracks caused by excessive local plastic deformation, further reducing the roughness of the inner hole.

[0066] It should be noted that the interference is defined as the maximum radius (R) of the 200mm rolling cutter. 滚刀 ) and the inner radius of the workpiece's 100mm hole (R) 孔 The theoretical difference is expressed mathematically as: δ = R 滚刀 -R 孔 The interference fit directly determines the radial compression depth of the roller 230 pressed into the bore wall.

[0067] In one embodiment, such as Figure 1 and Figure 2 As shown, step M is included before step S6:

[0068] Based on data from the first simulation experiment and offline experiments, a multiple regression model was established for roughness, chamfer radius, and interference fit:

[0069] Where Ra is the roughness, r is the chamfer radius, and δ is the interference fit;

[0070] By solving for the extreme points using partial derivatives, the optimal chamfer radius and optimal interference corresponding to the minimum roughness can be determined.

[0071] Determine the difference between the optimal chamfer radius and optimal interference calculated by the multiple regression model and the optimal chamfer radius and optimal interference obtained from the second simulation experiment. If the difference is within the preset difference range, proceed to step S6.

[0072] By establishing a multiple regression model of roughness in relation to chamfer radius and interference, The coupling effect of chamfer radius (r) and interference (δ) in roll forming is quantified into a nonlinear function relationship. Then, the extreme points of the model are solved by partial derivatives to accurately locate the optimal chamfer radius and optimal interference corresponding to the minimum roughness. The model calculation results are then verified by the difference between the two and the results of the second simulation experiment. The actual processing parameters are only executed when the difference between the two is within the preset range.

[0073] This application overcomes the blindness of parameter optimization in traditional processes through dual collaborative optimization of mathematical modeling and simulation verification. Before manufacturing the chamfer structure 231 of the roller 230 and setting the pressing depth, it ensures the reliability of the optimal parameters from a theoretical perspective and improves the accuracy of roughness control.

[0074] Specifically, such as Figure 2 As shown, if the difference is not within the preset difference range, return to step S1 and start the check again to determine if there is a problem with the establishment of the finite element model in step S1.

[0075] In one embodiment, step S1 includes:

[0076] A three-dimensional model of workpiece 100 with an inner hole is established, the material parameters of workpiece 100 are defined, and the elastic-plastic deformation relationship is established through the JC constitutive equation.

[0077] A three-dimensional model of the rolling cutter 200 is established, the maximum diameter of the roller 230 is defined, and the chamfer radius of the roller 230 is set with multiple parameters.

[0078] The interference fit when the rolling cutter 200 and the workpiece 100 are in contact has multiple parameters;

[0079] Through formula R 滚刀 =δ+R 孔 Calculate the maximum radius of the rolling cutter 200, where R 滚刀 R is the maximum radius of the 200mm rolling cutter, δ is the interference, and R is the maximum radius of the rolling cutter. 孔 The radius of the inner hole.

[0080] By establishing three-dimensional models of workpiece 100 and rolling cutter 200 and defining material parameters, the JC constitutive equation is used to describe the elastoplastic deformation behavior of the material during the rolling process, ensuring the accuracy of the physical mechanism of the finite element model. The maximum diameter of roller 230 is limited, and the chamfer radius and interference are parameterized to provide structured variable inputs for subsequent simulations. The formula R... 滚刀 =δ+R 孔 The maximum radius (R) of the associated rolling tool 200 滚刀 ), interference fit (δ) and inner hole radius (R) 孔 The relationship between the abstract interference parameters is transformed into manufacturable tool geometry, realizing quantitative coupling between process parameters and tool structure in the modeling stage. This lays the geometric foundation for the mapping relationship between roughness, chamfer radius, and interference in simulation experiments, and avoids simulation distortion caused by tool size design deviations.

[0081] In one embodiment, step S4 further includes step S41: if the error between the actual roughness and the simulated roughness is greater than a preset value, the JC constitutive equation of the material is corrected, and the strain rate sensitivity coefficient of the JC constitutive equation of the material is adjusted.

[0082] By comparing the actual roughness with the simulated roughness to determine whether the error exceeds a preset value, it is confirmed whether the JC constitutive equation in the finite element model needs to be corrected. The strain rate sensitivity coefficient of the constitutive equation is adjusted accordingly to correct the deviation in describing the plastic flow behavior of the material under high strain rate rolling conditions. Correcting the JC constitutive equation resolves the deviation between simulation and physical experiment at the level of material deformation mechanism, improving the finite element model's prediction accuracy of microscopic plastic deformation behavior during rolling, and laying the physical foundation for the accurate solution of the roughness minimization parameter in the subsequent second simulation experiment.

[0083] In one embodiment, when adjusting the strain rate sensitivity coefficient, the scale value of each adjustment is 0.001, the roughness error under multiple strain rate sensitivity coefficients is calculated, and the strain rate sensitivity coefficient under the minimum roughness error is set as the final strain rate sensitivity coefficient.

[0084] By setting a strain rate sensitivity coefficient with a scale value of 0.001 for each adjustment, the JC constitutive equation of the material is finely tuned with high precision. The roughness error under multiple sets of coefficients is calculated and compared and screened. The final strain rate sensitivity coefficient is determined with the minimum roughness error as the optimization target.

[0085] For example, when performing step S1, the strain rate sensitivity coefficient of the material JC constitutive equation is 0.002, while the maximum value of the strain rate sensitivity coefficient is 0.005. When adjusting the strain rate sensitivity coefficient in the subsequent steps, the scale value of each adjustment is 0.0001, that is, the strain rate sensitivity coefficients adjusted in the subsequent steps are 0.0021, 0.0022, 0.0023, ..., 0.005.

[0086] In one embodiment, establishing a three-dimensional model of a workpiece 100 with an inner hole includes: setting the mesh size of the inner hole wall to a first mesh value;

[0087] Step S4 also includes step S42: determining whether the first grid value setting is reasonable. If the roughness simulation value changes by less than 5% after reducing the first grid value, it is determined that the first grid value setting is reasonable; if the roughness simulation value changes by more than or equal to 5%, it is determined that the first grid value setting is unreasonable, and the grid size is adjusted.

[0088] By directly setting the mesh size of the inner hole wall as the first mesh value when creating the 3D model of workpiece 100, the mesh density of the contact area between roller 230 and the hole wall is controlled in a targeted manner; the rationality of the mesh size is dynamically judged with a 5% roughness error as the critical threshold: when the error is less than 5%, the current first mesh value is judged to be reasonable and can continue to be used; when the error is greater than or equal to 5%, the mesh size adjustment mechanism is triggered to avoid distortion of local plastic deformation characterization caused by excessively coarse mesh.

[0089] This application transforms the abstract mesh convergence verification into a quantifiable error criterion by judging the coarseness error. Under the premise of ensuring accurate capture of the stress gradient in the contact area, it eliminates the interference of mesh discretization error on surface roughness prediction from the numerical calculation level.

[0090] For example, when performing step S1, the first grid value is 0.05mm. When checking whether the grid size setting is reasonable, the grid size of the inner hole wall is refined from 0.05mm to 0.02mm (i.e., the first grid value is reduced). If the change in the roughness simulation value is less than 5%, it is judged that the original grid size (first grid value) setting is reasonable. If the change in the roughness simulation value (i.e., the roughness change rate) is greater than or equal to 5%, it is judged that the original grid size setting is unreasonable and the grid size needs to be adjusted.

[0091] In one embodiment, the interference parameter is set in the range of 0.1mm-0.16mm; in the first simulation experiment, the scale value of the interference is 0.02mm; in the second simulation experiment, the scale value of the interference is 0.01mm.

[0092] By limiting the interference parameter range to 0.1mm-0.16mm, the critical threshold for plastic deformation in aluminum alloy rolling is matched (exceeding 0.16mm easily induces microcracks, while below 0.1mm results in insufficient deformation). In the first simulation experiment, a coarse scale value of 0.02mm is used for a full-domain scan, which can quickly screen feasible combinations of chamfer radius and interference. In the second simulation experiment, the scale value is switched to a finer scale value of 0.01mm for local fine-tuning, achieving the location of the optimal parameters. By setting the scale values ​​in the first and second simulation experiments in a stepped manner, not only is computational redundancy in full-range fine-mesh simulation avoided, but the target of minimizing roughness within the sensitive range of interference (0.1-0.16mm) is also accurately captured.

[0093] For example, in this embodiment, the workpiece is made of aluminum alloy, and the interference parameter range is limited to 0.1mm-0.16mm. In the first simulation experiment, the interference δ is set to 0.10mm, 0.12mm, 0.14mm, and 0.16mm respectively. In the second simulation experiment, the interference δ is set to 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, and 0.16mm respectively.

[0094] In other embodiments, the parameter setting range of the interference fit is determined based on the relevant parameters of the actual simulated workpiece.

[0095] In one embodiment, the chamfer radius parameter is set within the range of 1.25mm-5mm. During the experiment, multiple values ​​for the chamfer radius are selected within this parameter range. For example, in the first simulation experiment and the offline experiment, the chamfer radius is set to 1.25mm, 2.5mm, and 5mm, respectively.

[0096] In one embodiment, the chamfer radius is divided into 0.25mm increments during the second simulation experiment. For example, the chamfer radii are 1.25mm, 1.5mm, 1.75mm, 2mm, 2.5mm, ..., 5mm during the second simulation experiment.

[0097] In summary, based on the above-described processing method for reducing the roughness of internal holes, in a specific embodiment of this application, the above-described processing method is used to process the internal hole of the aluminum alloy workpiece 100:

[0098] S1. Establish a finite element model of the contact between the rolling cutter 200 and the workpiece 100, wherein the rolling cutter 200 is provided with rollers 230 and the workpiece 100 is provided with an inner hole.

[0099] A three-dimensional solid model was established based on the internal hole structure of the aerospace lug (diameter 20mm, thickness 15mm). The material of workpiece 100 is aluminum alloy 7050, and the material parameters are defined as follows: elastic modulus 72GPa, Poisson's ratio 0.33, yield strength 470MPa, density 2.82g / cm3. The elastic-plastic deformation relationship was established through the JC constitutive model: initial yield stress A=436MPa, strain hardening modulus B=535MPa, strain hardening exponent n=0.504, strain rate sensitivity coefficient C=0.02, and temperature softening index m=0.97.

[0100] The roller burnishing tool 200 assembly includes rollers 230, protective sleeves 220, and mandrels 210. The maximum diameter of the rollers 230 is 5mm, and the chamfer radius is parameterized to three specifications: 1.25mm, 2.5mm, and 5mm.

[0101] The roller 230 is defined to have surface-to-surface contact with the hole wall, with the friction coefficient set to 0.12. The normal contact behavior adopts hard contact, and the tangential behavior uses the penalty function algorithm.

[0102] The outer edge of the constrained lug has full freedom. The roller 230 applies a rotational motion at a speed of 500 r / min and an axial feed motion at a feed rate of 0.4 mm / r. The interference is achieved by radial displacement loading and is set to 0.10 mm, 0.12 mm, 0.14 mm, and 0.16 mm, respectively.

[0103] Workpiece 100 uses C3D8R hexahedral elements, with the contact area of ​​the hole wall locally refined to 0.05mm. Roller 230 is simplified to an analytical rigid body, with a total mesh count of approximately 120,000.

[0104] Adaptive time step control is adopted, with a maximum increment step of 0.01s, to ensure the convergence of plastic deformation;

[0105] The single rolling stroke is set to 15mm, and the interference is applied through radial displacement. The simulation time for each set of working conditions is about 6 hours.

[0106] S2. Conduct the first simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference fit and different chamfer radii of roller 230.

[0107] With interference amounts δ set to 0.10mm, 0.12mm, 0.14mm, and 0.16mm, and chamfer radii of 1.25mm, 2.5mm, and 5mm, respectively, the roughness was tested under simulation conditions for different combinations of chamfer radii and interference amounts.

[0108] S3. Conduct offline experiments to measure the actual roughness of the inner hole wall of workpiece 100 under different combinations of interference fit and different chamfer radii of roller 230. In the first simulation experiment and offline experiment, the parameters of different interference fit and different chamfer radii of roller 230 are the same.

[0109] With interference amounts δ set to 0.10mm, 0.12mm, 0.14mm, and 0.16mm, and chamfer radii of 1.25mm, 2.5mm, and 5mm, respectively, the surface roughness was measured under different combinations of chamfer radii and interference amounts in an on-site offline experiment.

[0110] S4. Optimize the finite element model based on the simulated roughness and the actual roughness;

[0111] Based on the simulation and actual test results, a comparison of the roughness of the first simulation experiment and the offline experiment revealed that when the interference was 0.16 mm, the roughness error increased to 5.2%, mainly because the material hardening model did not consider the temperature effect.

[0112] Therefore, by modifying the JC constitutive equation of the material and adjusting the strain rate sensitivity coefficient C to 0.023, the error between the experimental and simulation values ​​is reduced to below 3%.

[0113] In addition, the mesh size setting of the inner hole wall was checked to see if it was reasonable: the mesh size of the hole wall was increased from 0.05mm to 0.02mm, and the Ra simulation value changed by less than 5%, confirming that the original mesh size setting was reasonable.

[0114] S5. Conduct a second simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference and different chamfer radii of roller 230, so as to obtain the optimal chamfer radius and optimal interference corresponding to the minimum roughness. The parameter scale value of the second simulation experiment is smaller than that of the first simulation experiment.

[0115] The simulation experiment was conducted again, with the interference δ set to 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, and 0.16mm, and the chamfer radii set to 1.25mm, 1.5mm, 1.75mm, 2mm, 2.5mm, ..., 5mm. According to the simulation experiment, the interference δ = 0.14mm and the chamfer radius r = 2.5mm are corresponding to the minimum roughness.

[0116] M. Verify the optimal interference fit and the optimal chamfer radius;

[0117] By combining experimental and simulation data, a multiple regression model was established for roughness, interference fit, and chamfer radius:

[0118] By solving for the coefficients using the least squares method, we obtain:

[0119] ;

[0120] Excess quantity quadratic term δ 2 The coefficient is +0.105, indicating that an appropriate increase in the interference fit can reduce the micro-unevenness of the specimen surface, but an excessive interference fit may cause surface defects, resulting in a trend of roughness first decreasing and then increasing.

[0121] chamfer radius quadratic term r 2 With a coefficient of +0.026, increasing the chamfer radius can reduce stress concentration, but if the critical value is exceeded, the contact time between the roller 230 and the inner hole wall of the specimen will be too long, which is not conducive to surface flatness.

[0122] The coefficient of the cross term δ⋅r is 0.03. This term reflects the synergistic effect of interference and chamfer radius, indicating that a large interference requires a moderate chamfer to balance the contact pressure.

[0123] The optimal parameters are obtained by solving for the extreme points using partial derivatives:

[0124] ; ;

[0125] make , ;

[0126] Clearly, the chamfer radius and interference amount corresponding to the optimal roughness are very close to the experimental results. The accuracy of the model was verified through residual analysis and error distribution. The standard deviation of the residuals was 0.02 μm, indicating that the model's prediction accuracy basically meets engineering requirements. Proceed to the next step.

[0127] S6. Based on the optimal chamfer radius, manufacture the chamfer radius of the roller 230, and adjust the depth of the rolling cutter 200 pressed into the hole wall during actual machining based on the optimal interference.

[0128] Based on the optimal chamfer radius of 2.5mm obtained in step S5, the chamfer on the roller 230 is machined, and based on the optimal interference of 0.14mm, the size adjustment of the rolling cutter 200 is adjusted when strengthening the inner hole.

[0129] In summary, the processing method of this application clarifies that the surface roughness of the inner hole is mainly affected by the coupling influence of the chamfer radius (R) and interference (δ) at the bottom of the roller 230. By changing the chamfer radius and interference of the roller 230, the influence of contact stress on surface roughness is analyzed based on finite element simulation. Combined with real cutting tests under multiple working conditions, a quantitative relationship model between chamfer radius, interference, and roughness is established. Through simulation and experimental optimization, the optimal chamfer parameters are determined, achieving precise control of the surface roughness of the inner hole. Experimental results show that this method can reduce the surface roughness of aluminum alloy specimens to below 0.03 μm, significantly improving processing quality.

[0130] This application also provides a processing system, such as Figures 3 to 6 As shown, the machining system includes:

[0131] The roller burnishing tool 200 includes a mandrel 210, a protective sleeve 220, and rollers 230. The mandrel 210 is used to connect to the machine tool spindle. The protective sleeve 220 is sleeved on the mandrel 210 and has a mounting groove. The rollers 230 are disposed in the mounting groove and can rotate relative to the mandrel 210. The side of the rollers 230 away from the machine tool spindle has a chamfer structure 231.

[0132] The controller is connected to the rolling cutter 200 and controls the rolling cutter 200 to process the inner hole of the workpiece 100 according to any of the above-mentioned machining methods for reducing the roughness of the inner hole.

[0133] The aforementioned machining system, by setting a chamfer structure 231 on the side of the roller 230 of the rolling cutter 200 away from the machine tool spindle, reduces the stress concentration factor at the contact edge between the roller 230 and the hole wall, thus suppressing the initiation of microcracks. Furthermore, the controller drives the rolling cutter 200 to execute the machining method, achieving a precise match between optimal chamfer radius manufacturing and optimal interference fit depth control. The integration of the chamfer structure 231 of the rolling cutter 200 and the optimization algorithm uniformizes the contact stress distribution between the bottom chamfer of the roller 230 and the inner hole wall, reducing the surface roughness of the aluminum alloy during rolling, while avoiding the rapid wear problem of traditional small-chamfer rollers 230.

[0134] In some embodiments, the processing system includes a fixture 300 and a mounting platform 400, the mounting platform 400 supporting the workpiece 100, the fixture 300 being disposed on the mounting platform 400 and clamping the workpiece 100 and the mounting platform 400.

[0135] In one embodiment, such as Figures 3 to 6 As shown, the spindle 210 includes a first section and a second section connected to each other, and the protective sleeve 220 is fitted onto the first section;

[0136] The rolling cutter 200 also includes an adjustment assembly 240, which includes:

[0137] The thrust bearing 241 is sleeved on the second section and abuts against the end face of the protective sleeve 220;

[0138] Adjusting sleeve 242 is sleeved on protective sleeve 220, thrust bearing 241 and second section, and is threadedly connected to second section;

[0139] The elastic element 243 is sleeved on the protective sleeve 220 and located inside the adjusting sleeve 242. The two ends of the elastic element 243 abut against the inner wall of the adjusting sleeve 242 and the end face of the thrust bearing 241, respectively.

[0140] By rotating the adjusting sleeve 242, the thrust bearing 241 and the protective sleeve 220 are moved axially along the mandrel 210, thereby adjusting the axial position of the roller 230. The thrust bearing 241, sleeved on the second section of the mandrel 210 and abutting against the end face of the protective sleeve 220, converts the axial load applied by the roller 230 into a radial constraint, eliminating the frictional torque between the protective sleeve 220 and the mandrel 210. The adjusting sleeve 242 is threadedly connected to the second section of the mandrel 210 and covers the protective sleeve 220 and the thrust bearing 241, achieving precise adjustment of the pressing depth through the feed accuracy of the helical pair. The elastic element 243 is pre-compressed between the inner wall of the adjusting sleeve 242 and the end face of the thrust bearing 241, dynamically absorbing the instantaneous impact load during the rolling process and maintaining a constant contact pressure.

[0141] In one embodiment, such as Figures 3 to 6 As shown, the rolling tool 200 also includes a clamping shank 250 connected to the spindle 210, and the spindle 210 is connected to the machine tool spindle via the clamping shank 250. The clamping shank 250 connects the spindle 210 and the machine tool spindle, forming a rigid force transmission chain to transmit the rotational power of the machine tool spindle to the rollers 230; while the clamping shank 250 is directly fixed to the spindle 210, reducing the axial movement and radial sway of the spindle 210.

[0142] It should be noted that the controller refers to the CNC unit integrated into the machining system. Its hardware includes an industrial computer, motion control card, and data acquisition module, while the software contains the algorithm program for the machining method. The controller is electrically connected to the adjustment assembly 240 of the rolling tool and the machine tool spindle servo system via cables.

[0143] The controller receives the optimal chamfer radius and optimal interference from the finite element model optimization output; and calculates the radial pressing depth in real time based on the optimal chamfer radius and optimal interference, generates control commands to drive the adjusting sleeve 242 of the adjusting component 240 to rotate, and converts the axial displacement through the threaded pair so that the roller 230 reaches the target pressing depth.

[0144] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0145] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A machining method for reducing the roughness of internal holes, characterized in that, The processing method for reducing the roughness of the inner hole includes: S1. Establish a finite element model of the contact between the rolling cutter and the workpiece, wherein the rolling cutter is provided with rollers and the workpiece is provided with an inner hole; S2. Conduct the first simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference fit and different chamfer radii of the roller; S3. Conduct offline experiments to measure the actual roughness of the inner hole wall of the workpiece under different combinations of interference fit and different chamfer radii of the roller, and the parameters of different interference fit and different chamfer radii of the roller are the same when conducting the first simulation experiment and the offline experiment. S4. Optimize the finite element model based on the simulated roughness and the actual roughness; S5. Conduct a second simulation experiment to simulate the roughness of the inner hole wall under different combinations of interference and different chamfer radii of the roller, so as to obtain the optimal chamfer radius and optimal interference corresponding to the minimum roughness. The parameter scale value of the second simulation experiment is smaller than the parameter scale value of the first simulation experiment. S6. Based on the optimal chamfer radius, manufacture the chamfer radius of the machining roller, and adjust the depth of the roller burnishing tool pressed into the hole wall during actual machining based on the optimal interference.

2. The machining method for reducing the roughness of internal holes according to claim 1, characterized in that, Step M is included before step S6: Based on the data from the first simulation experiment and the offline experiment, a multiple regression model was established for roughness, chamfer radius, and interference fit: Where Ra is the roughness, r is the chamfer radius, and δ is the interference fit; By solving for the extreme points using partial derivatives, the optimal chamfer radius and optimal interference corresponding to the minimum roughness can be determined. Determine the difference between the optimal chamfer radius and optimal interference calculated by the multiple regression model and the optimal chamfer radius and optimal interference obtained in the second simulation experiment. If the difference is within the preset difference range, proceed to step S6.

3. The machining method for reducing the roughness of internal holes according to claim 1, characterized in that, Step S1 includes: A three-dimensional model of a workpiece with an internal hole is established, the material parameters of the workpiece are defined, and the elastic-plastic deformation relationship is established through the JC constitutive equation. A three-dimensional model of the roller is established, the maximum diameter of the roller is defined, and the chamfer radius of the roller is set with multiple parameters. The interference fit between the rolling tool and the workpiece is set by multiple parameters; Through formula R 滚刀 =δ+R 孔 Calculate the maximum radius of the rolling cutter, where R 滚刀 R is the maximum radius of the rolling tool, δ is the interference, and R is the maximum radius of the rolling tool. 孔 The radius of the inner hole.

4. The machining method for reducing the roughness of internal holes according to claim 3, characterized in that, Step S4 further includes step S41: If the error between the actual roughness and the simulated roughness is greater than a preset value, the JC constitutive equation of the material is corrected, and the strain rate sensitivity coefficient of the JC constitutive equation of the material is adjusted.

5. The machining method for reducing the roughness of internal holes according to claim 4, characterized in that, When adjusting the strain rate sensitivity coefficient, the scale division value is 0.001 each time. The roughness error under multiple strain rate sensitivity coefficients is calculated, and the strain rate sensitivity coefficient under the minimum roughness error is set as the final strain rate sensitivity coefficient.

6. The machining method for reducing the roughness of internal holes according to claim 5, characterized in that, The process of establishing a three-dimensional model of a workpiece with an inner hole includes: setting the mesh size of the inner hole wall to a first mesh value; Step S4 further includes step S42: determining whether the first grid value setting is reasonable. If the roughness simulation value changes by less than 5% after reducing the first grid value, it is determined that the first grid value setting is reasonable; if the roughness simulation value changes by more than or equal to 5%, it is determined that the first grid value setting is unreasonable, and the grid size is adjusted.

7. The machining method for reducing the roughness of internal holes according to claim 3, characterized in that, The parameter setting range for the interference amount is 0.1mm-0.16mm; In the first simulation experiment, the scale division of the interference fit was 0.02 mm; In the second simulation experiment, the scale division of the interference fit was 0.01 mm.

8. A processing system, characterized in that, include: A rolling cutter, comprising: a mandrel, a protective sleeve, and rollers, wherein the mandrel is used to connect to a machine tool spindle; The protective sleeve is fitted onto the mandrel, and the protective sleeve has a mounting groove; the roller is disposed in the mounting groove and can rotate relative to the mandrel, and the side of the roller away from the machine tool spindle has a chamfer structure; A controller, communicatively connected to the rolling cutter, controls the rolling cutter to process the inner hole of the workpiece according to any one of claims 1-7 of the machining method for reducing the roughness of the inner hole.

9. The processing system according to claim 8, characterized in that, The mandrel includes a first section and a second section connected to each other, and the protective sleeve is fitted onto the first section; The rolling cutter further includes an adjustment component, which includes: A thrust bearing is sleeved on the second section and abuts against the end face of the protective sleeve; An adjusting sleeve is fitted onto the protective sleeve, the thrust bearing, and the second section, and is threadedly connected to the second section. An elastic element is fitted onto the protective sleeve and disposed within the adjusting sleeve, with its two ends respectively abutting against the inner wall of the adjusting sleeve and the end face of the thrust bearing.

10. The processing system according to claim 8, characterized in that, The rolling tool also includes a clamping shank connected to the mandrel, and the mandrel is connected to the machine tool spindle via the clamping shank.

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