Method for measuring residual stress on surface of milling part based on strain change and inverse inference method

Abstract

The invention discloses a method for measuring the residual stress on the surface of a milling part based on strain change and an inverse inference method, which belongs to the field of mechanical engineering. In the traditional measurement process of the residual stress on the surface of a milling part based on an X-ray method, the measured residual stress often reaches the stress value after theequilibrium state, and the equipment used is expensive. In the invention, the strain change of the back of a milled side in the stripping process of a residual stress layer on the surface is measured. Meanwhile, in view of the transformation of bending moment caused by the residual stress in the remaining residual stress layer after each stripping due to the position change of the neutral layer,calculation is carried out from the bottommost layer and inverse inference is carried out step by step from bottom to top until the residual stress value in the topmost layer is calculated. Thus, themeasurement of surface residual stress changing with depth in the whole milling process is completed. The equipment required in the whole process is inexpensive, and the operation is simple. The measured value can be used to accurately predict the deformation of stress of various shapes and sizes caused by the surface residual stress and the distribution of the actual residual stress inside a partafter the internal stress eventually reaches equilibrium.

Description

Technical field: [0001] The invention relates to a method for measuring the residual stress on the surface of a milled part based on the measurement of the strain change on the surface of the part and a reverse deduction method, which belongs to the stress measurement method in the field of mechanical engineering. Background technique: [0002] Residual stress, that is, internal stress, its nature and size will seriously affect the service performance and life of parts. In industry, manufacturers often pay more attention to improving the beneficial effect of residual stress and reducing its harmful effect, thereby further improving product quality. . [0003] During the cutting process of metal parts, a layer of residual stress layer will be formed on the surface of the final part. In this stress layer, the distribution of residual stress is very shallow, generally not exceeding 0.2mm, but in the depth direction. High rate of change, the size and nature of the stress value ...

AI Technical Summary

Problems solved by technology

[0004] For the research of surface residual stress, it often starts from the measurement of its value changing with depth. At present, the relatively mature measurement technology is X-ray method combined with delamination method. However, due to the distribution of the final surface residual stress value of parts to a large extent It is affected by the rigidity of the parts, so even if the same part material, the same processing method, processing parameters, and processing conditions, due to the inconsistency of the rigidity of the parts, it may eventually lead to inconsistent stress values ​​after reaching self-balance, so X-ray The surface residual stress value of a part finally measured by the method combined with the delamination method is not representative.

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