Mechanical part pre-deformation clamping process method based on simulation analysis

Abstract

The invention discloses a mechanical part pre-deformation clamping process method based on simulation analysis, and relates to the technical field of mechanical manufacturing. The method comprises the following steps that S1, a design drawing, material characteristic parameters, blank size specifications and technical parameters of a clamp system of a to-be-machined part are collected; according to the method, an integrated simulation model of a part, blank and clamp system is constructed, blank key parameters and the constraint relation of all parts are fused, multi-field coupling simulation is combined, the theoretical deformation field pre-judgment precision is greatly improved, reliable data support is provided for pre-deformation design, a target compensation curved surface is generated through a geometric inversion algorithm, and the pre-deformation design precision is improved. By matching with a pre-deformation clamp with an adjusting mechanism, reverse pre-deformation is realized, differences of different batches of blanks are adapted, machining and rebound deformation are effectively counteracted, simulation and process parameters are corrected through a detection result by means of a closed-loop optimization mechanism, machining precision stability is guaranteed, trial cutting cost and rejection rate are reduced, and the method is suitable for machining of various easily-deformed parts.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mechanical manufacturing, and particularly relates to a mechanical part pre-deformation clamping process method based on simulation analysis. BACKGROUND

[0002] In high-precision industries such as aerospace, precision instruments and automobile molds, there are a large number of thin-walled, complex-shaped, frame-shaped and large initial residual stress mechanical parts. In the cutting process of such parts, the overall structural rigidity is significantly reduced due to the large amount of material removed. At the same time, under the coupling action of cutting force, clamp clamping force and cutting heat, the workpiece will produce significant elastic or even elastic-plastic deformation. More troublesome is that when the machining is completed and the clamp is loosened, the internal stress accumulated in the workpiece will be redistributed and released, causing the machined part to deviate from the theoretical design model and produce springback deformation, so that the final geometric size and tolerance are seriously out of tolerance, which cannot meet the design requirements.

[0003] To solve the machining deformation problem of the easily deformed parts, the pre-deformation clamping technology based on simulation analysis has been gradually developed in the industry. The machining deformation law of the part is predicted by a simulation tool, and a reverse pre-deformation clamping scheme is designed to offset the actual deformation and the pre-deformation in the machining process, thereby improving the machining precision. At present, the existing pre-deformation clamping process based on simulation analysis mainly builds a three-dimensional model of the part and the clamp, simulates the deformation process under the action of clamping force and cutting force, calculates the pre-deformation amount based on the deformation data output by the simulation, and then designs a special pre-deformation clamp.

[0004] The existing technology ignores the influence of the geometry, material uniformity and machining allowance distribution of the blank on the deformation, and only simulates the ideal state of the part to be machined. In actual machining, the initial size deviation, surface roughness and internal stress distribution of the blank will change the stress state and deformation trend of the part. The simulation model lacking these key factors cannot restore the actual machining scene, resulting in a large deviation between the theoretical deformation field and the actual deformation, and further inaccurate pre-deformation parameter calculation.

[0005] Therefore, we provide a mechanical part pre-deformation clamping process method based on simulation analysis to solve the above problems. SUMMARY

[0006] The purpose of the present application is to provide a mechanical part pre-deformation clamping process method based on simulation analysis, which solves the problem that the mechanical part in the prior art produces uncontrollable deformation due to the coupling action of clamping force, cutting force and cutting heat in the cutting process, resulting in a decrease in the final machining precision, and lacks quantitative prediction and reverse compensation means for complex deformation, and cannot realize high-precision pre-deformation clamping.

[0007] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution.

[0008] This invention relates to a simulation-based pre-deformation clamping process method for mechanical parts, comprising the following steps: S1: Collect the design drawings, material properties, blank size specifications, and technical parameters of the fixture system for the parts to be processed. Use 3D modeling software to construct an initial simulation model containing the parts to be processed, blanks, and fixture system. The fixture system includes positioning elements, clamping elements, and auxiliary support elements. Define the assembly relationships, contact conditions, and constraint boundaries between the components in the simulation model. S2: Configure cutting process parameters, cutting tool geometric parameters, and machining environment parameters in the simulation software, perform full-process cutting simulation on the initial simulation model, simulate the relative motion between the cutting tool and the blank, the cutting load and energy transfer process, and obtain the theoretical deformation field of the part in the free state after machining. S3: Based on the theoretical deformation field, extract the deformation data of key machining surfaces and feature areas of the part, use the geometric inversion algorithm to solve the inverse solution, calculate the compensation amount corresponding to each deformation position, and generate a target compensation surface that matches the design shape of the part according to the distribution law of the compensation amount. S4: Based on the contour features and dimensional parameters of the target compensation surface, design the overall structure of the pre-deformation fixture, determine the shape contour and spatial position of the fixture positioning surface and clamping surface, so that the blank can produce a pre-deformation opposite to the theoretical deformation direction after clamping, manufacture the pre-deformation fixture and perform assembly and debugging. S5: Check the dimensional accuracy and surface condition of the actual blank, position it on the positioning surface of the pre-deformation fixture, apply the preset clamping force through the clamping element to ensure that the blank is in close contact with the positioning surface and clamping surface of the fixture and maintains the pre-deformation state, and then perform cutting processing according to the preset cutting process parameters.

[0009] The present invention is further configured such that the dimensional accuracy of the initial simulation model is consistent with the design drawings, and the key feature surfaces of the parts, the machining allowance of the blank, and the functional structural details of the fixture system are fully preserved.

[0010] The present invention is further configured such that the material property parameters include elastic modulus, Poisson's ratio, density, coefficient of thermal expansion and yield strength, the contact conditions include contact type, coefficient of friction and normal constraint stiffness, and the constraint boundary includes the positioning constraint and motion restriction of the fixture on the blank.

[0011] The present invention is further configured such that the cutting process parameters include cutting speed, feed rate, depth of cut and cutting fluid supply method, the cutting tool geometric parameters include cutting edge angle, tool radius and tool length, and the machining environment parameters include ambient temperature, humidity and heat exchange conditions.

[0012] The present invention is further configured such that the theoretical deformation field includes the deformation amount, deformation direction, deformation gradient and stress distribution state of each node of the part, which is extracted by the post-processing module of the simulation software and output in the form of data reports and deformation cloud maps.

[0013] The present invention is further configured such that the geometric inversion algorithm takes the designed shape of the part as a reference, uses the nodal deformation amount in the theoretical deformation field as the inverse input, and obtains a set of compensated nodes by performing compensation calculations on the corresponding node coordinates of the designed curved surface. satisfy: ; in: To design the coordinates of the surface nodes, This represents the nodal deformation in the theoretical deformation field. For the compensation coefficients, the solution of the compensation surface further employs an iterative inversion update model, satisfying: ; in, For the first The compensation surface of the next iteration. This represents the residual deformation field obtained from the simulation under this iteration. The iteration step size is used to determine the final compensation surface when the residual deformation satisfies the following convergence condition: .

[0014] The present invention is further configured such that the design of the pre-deformation fixture also includes a pre-deformation adjustment mechanism based on the target compensation surface. The adjustment mechanism includes a fine-tunable ejector pin, a hydraulic telescopic component, and an elastic support block to adapt to the dimensional deviations and deformation differences of different batches of blanks.

[0015] The present invention is further configured such that, in S4, the pre-deformed fixture that has been manufactured is subjected to precision calibration to ensure that the contour accuracy and spatial position accuracy of the positioning surface and clamping surface meet the design requirements of the target compensation surface.

[0016] The present invention is further configured to include S6: after the cutting process is completed, a coordinate measuring machine is used to detect the dimensional accuracy, shape accuracy and positional accuracy of the part, and the detection results are compared with the design requirements. If there is a deviation, it is fed back to the initial simulation model, and after correcting the cutting process parameters, contact conditions and constraint boundaries, the steps S2-S5 are repeated to achieve process closed-loop optimization.

[0017] The present invention is further configured such that the cutting process simulation is performed using finite element simulation software, and the coupled effects of cutting force, cutting heat and clamping force on the deformation of the part are comprehensively considered.

[0018] The present invention has the following beneficial effects.

[0019] This invention constructs an integrated simulation model of the part, blank, and fixture system, incorporating key blank parameters and constraint relationships of each component. Combined with multi-field coupled simulation, it significantly improves the accuracy of theoretical deformation field prediction, providing reliable data support for pre-deformation design. It uses a geometric inversion algorithm to generate a target compensation surface, and with a pre-deformation fixture with an adjustment mechanism, it achieves reverse pre-deformation, adapting to differences in different batches of blanks and effectively offsetting processing and springback deformation. With the help of a closed-loop optimization mechanism, it corrects simulation and process parameters through detection results, ensuring the stability of processing accuracy, reducing trial cutting costs and scrap rate, and is suitable for processing various easily deformable parts. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0021] Figure 1 This is the main flowchart of a simulation analysis-based pre-deformation clamping process for mechanical parts.

[0022] Figure 2 This is a flowchart of simulation modeling in a simulation analysis-based pre-deformation clamping process for mechanical parts.

[0023] Figure 3 This is a flowchart of geometric inversion and compensation surface generation in a simulation-based pre-deformation clamping process for mechanical parts.

[0024] Figure 4 This is a flowchart of the design and manufacturing of a pre-deformation fixture in a simulation-based pre-deformation clamping process for mechanical parts.

[0025] Figure 5 This is a flowchart of closed-loop detection and optimization in a simulation-based pre-deformation clamping process for mechanical parts. Detailed Implementation

[0026] The technical solutions of the present invention will be described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Please see Figures 1-5 This invention provides a simulation-based pre-deformation clamping process method for mechanical parts, comprising the following steps: S1: Collect the design drawings, material properties, blank size specifications, and technical parameters of the fixture system for the parts to be processed. Use 3D modeling software to construct an initial simulation model containing the parts to be processed, blanks, and fixture system. The fixture system includes positioning elements, clamping elements, and auxiliary support elements. Define the assembly relationships, contact conditions, and constraint boundaries between the components in the simulation model. S2: Configure cutting process parameters, cutting tool geometric parameters, and machining environment parameters in the simulation software, perform full-process cutting simulation on the initial simulation model, simulate the relative motion between the cutting tool and the blank, the cutting load and energy transfer process, and obtain the theoretical deformation field of the part in the free state after machining. S3: Based on the theoretical deformation field, extract the deformation data of key machining surfaces and feature areas of the part, use the geometric inversion algorithm to solve the inverse solution, calculate the compensation amount corresponding to each deformation position, and generate a target compensation surface that matches the design shape of the part according to the distribution law of the compensation amount. S4: Based on the contour features and dimensional parameters of the target compensation surface, design the overall structure of the pre-deformation fixture, determine the shape contour and spatial position of the fixture positioning surface and clamping surface, so that the blank can produce a pre-deformation opposite to the theoretical deformation direction after clamping, manufacture the pre-deformation fixture and perform assembly and debugging. S5: Check the dimensional accuracy and surface condition of the actual blank, position it on the positioning surface of the pre-deformation fixture, apply the preset clamping force through the clamping element to ensure that the blank is in contact with the positioning surface and clamping surface of the fixture and maintains the pre-deformation state, and then perform cutting processing according to the preset cutting process parameters.

[0028] Implementation 1 Taking a typical thin-walled frame part as the machining object, this part is characterized by thin walls, large structural openings, and insufficient rigidity, belonging to one of the most typical part types prone to machining deformation and springback deformation. When using the method of this invention, an initial simulation model containing the actual blank shape and fixture structure is first constructed based on the part design drawings. The contact conditions between the frame sidewall and the fixture positioning surface are defined in the model to ensure the simulation accurately reflects the local deformation trend caused by the clamping force. Simultaneously, considering the influence of the material removal sequence on the stiffness of the thin-walled structure, the stress redistribution process of the sidewall region gradually losing support during the cutting process is simulated.

[0029] Through cutting simulation, the deformation direction and deformation distribution of the thin-walled frame sidewall in a free state can be obtained. This deformation field is then input into a geometric inversion algorithm to perform reverse compensation calculations on nodes with significant deformation in the sidewall region. After fitting the compensated nodes, a slightly warped inward or outward compensation surface is obtained. A dedicated pre-deformation fixture is designed based on the shape of the compensation surface, so that the blank automatically generates a pre-deformation amount opposite to the deformation direction predicted by the simulation during clamping.

[0030] In actual machining, the transient deformation of the sidewall under the combined action of cutting force and clamping force is basically consistent with the simulation prediction. The reverse pre-deformation caused by the compensation surface effectively cancels out the deformation during actual machining. After cutting is completed and the fixture is released, the springback tendency of the frame sidewall due to elastic recovery is canceled out by the pre-deformation, thus making the final part shape close to the design requirements. This embodiment verifies that the method of the present invention has a good suppression effect on the deformation of thin-walled structures.

[0031] Example 2 The blanks of the parts to be processed exhibit significant uneven machining allowances, with some areas having excessively large allowances while others have smaller allowances. Traditional machining methods typically treat the blanks as ideal, but this invention introduces realistic differences in blank allowances into the simulation model, enabling the simulation to more accurately reflect the impact of material removal processes on local deformation of the parts.

[0032] In practical implementation, the geometric deviation, allowance distribution, and surface quality of the blank are first incorporated into the simulation model, enabling the simulation to depict the concentrated deformation caused by uneven stress in areas with large allowances after cutting. Simultaneously, the combined deformation trend of each region is obtained through coupled simulation of clamping force and cutting force. After simulation, a theoretical deformation field with significantly differentiated deformations is obtained. Then, a geometric inversion algorithm is used to apply greater inverse compensation to areas with large deformations and smaller compensation to areas with small deformations, resulting in a spatially uneven distribution of compensation.

[0033] The compensation surface obtained by fitting the compensation nodes not only matches the overall structure of the part design surface, but also exhibits differentiated micro-deformations in local areas. The pre-deformation fixture designed based on this compensation surface can automatically generate corresponding spatial deformation compensation effects after the blank is clamped. Actual machining shows that this method can effectively reduce the accumulation of local deformation caused by uneven allowance, resulting in a more balanced overall flatness, straightness, and contour of the machined part, thus improving the overall machining quality.

[0034] Example 3 To address potential differences in initial dimensions, surface roughness, and initial stress distribution between different batches of blanks, this invention employs an adjustable pre-deformation fixture. This fixture includes a fine-tunable ejector pin, a hydraulic telescopic assembly, and an elastic support block, used to fine-tune the fixture according to its real-time dimensions before actual clamping, ensuring the blank conforms as closely as possible to the compensating curved surface.

[0035] In the actual implementation process, the initial simulation model is established based on the blank design dimensions. However, before actual clamping, key geometric parameters of the blank, such as local thickness deviation, edge warping, and contact surface flatness, are measured, and the measurement results are used as the basis for fixture adjustment. By adjusting the height of the ejector pin, the extension and retraction of the hydraulic components, or the position of the elastic support block, the fit between the blank and the compensation surface is optimized, thereby improving the consistency of the pre-deformation effect.

[0036] In this embodiment, the adjustable fixture enables real-time adaptation to the blank clamping state, making the compensation effect independent of the blank's consistency or batch stability. Even if there are significant differences between different batches of blanks, the same pre-deformation effect can still be obtained through the fixture's fine-tuning mechanism, significantly improving the accuracy and stability of the machined parts. This embodiment demonstrates that the pre-deformation clamping method of the present invention has good flexibility and versatility, and is suitable for high-precision machining environments with multiple varieties and small batches.

[0037] Example 4 To further improve the compensation accuracy, the closed-loop optimization mechanism proposed in this invention is adopted. First, the compensation surface is obtained based on the initial simulation model and the first clamping and machining is performed. After machining, a coordinate measuring machine is used to comprehensively measure the final shape of the part and record the deviation distribution of each key feature surface.

[0038] The measurement results were then fed back to the simulation model to correct the contact parameters, clamping boundary constraints, and cutting process parameters, making the updated simulation model closer to the actual machining process. Based on the corrected simulation results, an updated compensation surface was regenerated, and the parameters of the pre-deformation fixture were adjusted accordingly. During the second machining operation, the actual deformation trend of the part was more accurately compensated due to the improved simulation accuracy.

[0039] If local deviations still exist after processing, the above feedback correction process is repeated by measuring again to bring the compensation to the final optimal state. This embodiment demonstrates that this closed-loop compensation mechanism continuously improves the accuracy of compensation through multiple iterations, achieving high-precision processing without the need for numerous trial cuts, reducing the accumulation of processing errors, and improving processing consistency.

[0040] The preferred embodiments of the present invention disclosed above are only for the purpose of illustrating the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can better understand and utilize the present invention.

Claims

1. A simulation-based pre-deformation clamping process method for mechanical parts, characterized in that: Includes the following steps: S1: Collect the design drawings, material properties, blank size specifications, and technical parameters of the fixture system for the parts to be processed. Use 3D modeling software to construct an initial simulation model containing the parts to be processed, the blank, and the fixture system. The fixture system includes positioning elements, clamping elements, and auxiliary support elements. Define the assembly relationship, contact conditions, and constraint boundaries between the components in the simulation model. S2: Configure cutting process parameters, cutting tool geometric parameters, and machining environment parameters in the simulation software, and perform a full-process cutting simulation on the initial simulation model to simulate the relative motion between the cutting tool and the blank, the cutting load, and the energy transfer process, and obtain the theoretical deformation field of the part in the free state after machining. S3: Based on the theoretical deformation field, extract the deformation data of the key machining surfaces and feature areas of the part, use the geometric inversion algorithm to solve the inverse solution, calculate the compensation amount corresponding to each deformation position, and generate a target compensation surface that matches the design shape of the part according to the distribution law of the compensation amount. S4: Based on the contour features and dimensional parameters of the target compensation surface, design the overall structure of the pre-deformation fixture, determine the shape contour and spatial position of the fixture positioning surface and clamping surface, so that the blank can produce a preset pre-deformation opposite to the theoretical deformation direction after clamping, manufacture the pre-deformation fixture and perform assembly and debugging. S5: Check the dimensional accuracy and surface condition of the actual blank, position it on the positioning surface of the pre-deformation fixture, apply a preset clamping force through the clamping element to ensure that the blank is in close contact with the positioning surface and clamping surface of the fixture and maintains the pre-deformation state, and then perform cutting processing according to the preset cutting process parameters.

2. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: The initial simulation model has the same dimensional accuracy as the design drawings, and fully preserves the key feature surfaces of the parts, the machining allowance of the blank, and the functional structural details of the fixture system.

3. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: The material properties include elastic modulus, Poisson's ratio, density, coefficient of thermal expansion and yield strength. The contact conditions include contact type, coefficient of friction and normal constraint stiffness. The constraint boundaries include the positioning constraint and movement restriction of the fixture on the blank.

4. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: The cutting process parameters include cutting speed, feed rate, depth of cut and cutting fluid supply method; the cutting tool geometry parameters include cutting edge angle, tool radius and tool length; and the machining environment parameters include ambient temperature, humidity and heat exchange conditions.

5. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: The theoretical deformation field includes the deformation amount, deformation direction, deformation gradient, and stress distribution state of each node of the part. It is extracted by the post-processing module of the simulation software and output in the form of data reports and deformation cloud maps.

6. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: The geometric inversion algorithm uses the part's designed shape as a reference, takes the nodal deformation in the theoretical deformation field as inverse input, and obtains a set of compensated nodes by compensating the corresponding node coordinates of the designed curved surface. satisfy: ; in: To design the coordinates of the surface nodes, This represents the nodal deformation in the theoretical deformation field. For the compensation coefficients, the solution of the compensation surface further employs an iterative inversion update model, satisfying: ; in, For the first The compensation surface of the next iteration. This represents the residual deformation field obtained from the simulation under this iteration. The iteration step size is used to determine the final compensation surface when the residual deformation satisfies the following convergence condition: .

7. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: The design of the pre-deformation fixture also includes a pre-deformation adjustment mechanism based on the target compensation surface. The adjustment mechanism includes a fine-tuning ejector pin, a hydraulic telescopic component, and an elastic support block to adapt to the dimensional deviations and deformation differences of different batches of blanks.

8. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: In step S4, the pre-deformed fixture that has been manufactured is subjected to precision calibration to ensure that the contour accuracy and spatial position accuracy of the positioning surface and clamping surface meet the design requirements of the target compensation surface.

9. The method for pre-deformation clamping of mechanical parts based on simulation analysis according to claim 1, characterized in that: It also includes S6: After the cutting process is completed, a coordinate measuring machine is used to check the dimensional accuracy, shape accuracy and positional accuracy of the part. The test results are compared with the design requirements. If there is a deviation, it is fed back to the initial simulation model. After correcting the cutting process parameters, contact conditions and constraint boundaries, the steps S2-S5 are repeated to achieve process closed-loop optimization.

10. The simulation analysis-based pre-deformation clamping process method for mechanical parts according to claim 1, characterized in that: The cutting process simulation was performed using finite element simulation software, taking into account the coupled effects of cutting force, cutting heat, and clamping force on part deformation.

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