Geometric Prediction Of Serrated Chip In High-speed Machining Of Aluminum Alloys7A04

It is easy to produce saw-tooth chips in the high-speed machining aluminum alloy, consequently causing the high frequency vibration of cutting force and affecting the work surface quality. Therefore, forecasting of serrated chip of high-speed machining and determination of the variation of serrated chip formation and high-speed cutting parameter has great value in academicand engineering area for the promotion of the development and application of high-speed cutting technology.In this dissertation, forecasting geometry of serrated chip in the high-speed cutting of super-hard aluminum alloy7A04and recombination of cutting parameters, which avoids serrated chips generated and further improves the quality of processing, is investigated by theoretical modeling and experimental verification.First, based on analysis of the serrated chip formation process, by using adiabatic shear theory, an orthogonal cutting model with two shear angle is established, the model can reflect serrated chip geometry in the high-speed machining of super-hard aluminum alloy7A04. And according to the model, calculation formula of serrated chip shape in high-speed machining of super-hard aluminum alloy7A04is derived.Second, Considering the effect of strain, strain rate and temperature, the two shear angles are deduced by appling to Oxley prediction theory. Using single factor analysis method, the sawtooth degree and spacing is calculated, and the change of the serrated chip shape with cutting velocity and the cutting tool’s geometry shape is studied by Matlab software. The effects of cutting conditions and tool geometry in high-speed machining are obtained.Third, high speed orthogonal cutting process experiment is designed using the five-axis milling machine. Calculate sawtooth degree and sawtooth spacing of the serrated chip after collecting and measuring. The variation of the chip shape and cutting conditions on the serrated chip shape with that in the theoretical results were compared to verify the rationality of the theoretical model.Forth, to control of saw-tooth chip formation, and get good surface quality and find reasonable cutting parameters matching, then the orthogonal cutting test in high-speed machining of super-hard aluminum alloy7A04is designed. According to the experimental results, combined with serrated chip formation conditions, this paper analyzes the relationship between different cutting dosage, chip morphology and surface roughness, cutting parameter selection principle not only can reduce the surface roughness but also can avoid serrated chip is given.