Study Of Relevance Between Tool-Path And Machined Residual Stress State

The machined residual stress generated by the intensive coupling effect of heat and force not only directly effects the fatigue life and corrosion resistance, but it makes the machining precision of parts, like large-scale thin-walled parts, hard to control. Thus the machined residual stress becomes a key aspect that should be considered during the high-performance part manufacture. Otherwise in reality the process planning and machining parameters are always made without considering the influence of residual stress. Moreover, the traceability and prediction is difficult due to various effect factors like tool, workpiece material, cutting parameters, tool path, etc. In this article, aiming at the high-performance manufacturing of large-scale thin-walled parts like the grid panel of rocket tank, the relevance between tool path and machined residual stress state are investigated.To address the problem that the influences on residual stress by main deformation areas remain undefined, a residual stress prediction model based on the cutting deformation area separation is established, and the accuracy is verified by comparing with the experiment results. Then, with the material of Aluminum Alloy 7075-T651, its residual stress generating mechanism is analyzed by utilizing the prediction model, and the influence law of multi-depth cutting on the residual stress distribution is revealed.An orthogonal experiment is carried out with various milling parameters of spindle speed, depth of cut, feed speed and tool path to compare the induced surface residual stress. Thus, the effect law of the parameters on the value and standard deviation of plane residual stresses is obtained. And the order of importance of tool path relative to other parameters is revealed.Specific to three typical grid milling tool paths, a single-factor experiment is carried out under the paths, and the residual stress states of two directions generated by the paths are measured. Afterwards, the patterns of the stress states under different tool paths are analyzed, and the uniformity of stress distribution effected by the paths are compared by calculating the gradient of each residual stress fields.The simulate model established in this article provides a rapid way to predict the residual stress, and an effective advice about layer milling method is given in this article. Through the multi-path milling experiment results, the importance of tool path and the relevance between tool path and residual stress are analyzed, which gives a thought on the subsequent tool path planning research and practical machining process.