Effect of Milling Vibration on The Machining Performance of 7075-T651 Aluminum Alloys

Milling of 7075-T651 is widely used in aerospace industry, however the process vibration restricts the machining performance in milling process. This paper puts forward a study on the effect of vibration on machining performance in milling to improve the machining quality. According to the characteristics of end milling, the process vibration is calculated and added based on the unformed chip thickness model of milling, and a milling simulation model considering vibration is established. Applying the finite element model and milling experiments, the simulation model is verified, the results proves the accuracy of the FEM models in predicting the milling force and milling temperature. Furthermore, the effect of milling vibration on machining performance is studied by numerical simulation, in which the relationship between amplitude-frequency characteristics and milling force-temperature fluctuation.

Identification method for the dynamic cutting force variation of a high energy efficiency milling cutter

The dynamic cutting force of a high energy efficiency milling cutter is an important indicator for evaluating the stability of the cutting energy efficiency. The existing cutting force analysis focuses on the main characteristics and influencing factors of the cutting force variation in the cutting process, ignoring the influence of the variation of the cutting layer parameters with the cutter tooth error in different cutting stages, and the dynamic cutting force variation is uncertain. In this research, the analytical model of the instantaneous cutting volume of a milling cutter was developed in order to obtain the time-frequency characteristics of the instantaneous cutting volume with the cutter tooth error. According to the sudden changes of the cutting force and the milling vibration, the variations were studied in different cutting stages. The dynamic cutting behavior sequences such as the instantaneous cutting volume, milling vibration, and dynamic cutting force were constructed to characterize the mapping relationship between the dynamic cutting behavior of a milling cutter. Based on these approaches, the identification method for the dynamic cutting force variation of a high energy efficiency milling cutter was proposed. The effectiveness of the method was verified by the results of the milling experiment and the dynamic cutting behavior response analysis. The results showed that the proposed method could effectively identify the variation and its control variables for the dynamic cutting force in the cutting process, and the method could provide a scientific basis for constructing the dynamic cutting force model of a high energy efficiency milling cutter.

Multi-point substructure coupling method to compensate multi-accelerometer masses in measuring rotation-related FRFs

Tool-tip Frequency Response Functions (FRFs) are often required in milling vibration analysis. Receptance coupling substructures analysis (RCSA) affords an efficient analytical way for different tool-tip FRFs prediction with only one modal test. The coupling theory includes both translational and rotational degrees of freedom, so rotation-related FRFs are essential to know in the test. The finite-differential technique is generally used to measure these special FRFs due to the avoidance of specialist equipment. The technique uses several translational accelerometers spatially placed close to each other to approximate the rotational vibration. However, the added sensor masses lead to the frequency shift of the test structure, and the phenomenon would aggravate as the sensors increase. The polluted measurement data would subsequently decrease the tool-tip FRFs prediction accuracy. Addressing this problem, this paper introduces a multi-point substructure coupling method to simultaneously compensate the multi-accelerometer masses in a single experimental setup. The proposed method considers the installed accelerators as multiple point masses and then uses inverse coupling calculation to isolate their effect. The compensation procedure is first effectively validated in simulation and experiment, and then it is integrated into an RCSA-based application of predicting different tool-tip dynamics. Experimental results show that the compensated FRF data can improve prediction accuracy, especially when predicting tools shorter than the tested tool.

Correlation analysis of noise sound pressure and vibration in aluminum alloy milling

To study the correlation between noise and vibration during dry milling of aluminum alloy, a synchronous acquisition system of noise and vibration was established. Based on the experimental data, the effects of three milling parameters on milling noise and milling vibration were analyzed. Based on the least square method and MATLAB software programming, the multiple regression models of milling noise on milling parameters and milling vibration were established. According to the regression models, it is found that there is a strong correlation between milling noise, milling parameters, and milling vibration. The maximum value of the correlation coefficient R is 0.98. It also shows that the regression models based on milling parameters and milling vibration can well predict the noise of aluminum alloy during milling. In addition, the obtained model can provide a control equation for the future coupling analysis of vibration and noise and for the numerical simulation.