Study On Tool Vibration Characteristics Under Different Chip Morphology

Titanium alloy is widely used in many fields such as aerospace,ships,engines,etc.because of its excellent performance,but because of its difficult-to-machine material properties,many problems such as low cutting efficiency,high cutting temperature,strong tool vibration,serious tool wear,etc.appear.High-speed cutting of titanium alloy is easy to produce sawtooth chips,which will cause the fluctuation of cutting force and the high-frequency vibration of cutter,which will affect the processing quality of workpiece.Therefore,this topic studies and analyzes the chip morphology and tool vibration characteristics of different sawtooth degrees in the process of high-speed cutting titanium alloy.The main research contents and results are as follows:(1)The single-factor cutting test of titanium alloy TC4 was carried out,and the vibration acceleration signal data were collected,and the chip was analyzed by metallography,so as to explore the changing law of vibration acceleration signal and chip shape under different cutting parameters.The experimental results show that with the increase of cutting speed,the amplitude of vibration signal first increases and then decreases,and the accompanying chip shape changes from band to sawtooth;With the increase of feed rate or back engagement of the cutting edge,the amplitude of vibration signal increases,and the sawtooth chips are the main chips,and the sawtooth unit increases continuously.(2)Calculate the effective value of the collected vibration acceleration signal,and analyze the effective value of vibration acceleration under single factor and orthogonal test scheme,and explore the influencing factors of tool vibration characteristics from the aspects of cutting parameters,chip sawtooth degree and cutting force.The research shows that the vibration acceleration increases with the increase of feed rate or back engagement of the cutting edge under different cutting parameters.The increase of cutting speed will reduce tool vibration.With the increase of cutting speed,the degree of serration and vibration acceleration show an opposite trend;With the increase of feed rate,the degree of sawtooth and the trend of vibration acceleration increase;After comprehensive analysis,it is concluded that high cutting speed,low feed rate and back engagement of the cutting edge should be adopted in cutting.The instability of chip formation process will cause high-frequency fluctuation of cutting force,and then lead to tool vibration.It is found that with the change of feed rate,the greater the degree of chip serration,the greater the fluctuation of cutting force and the corresponding vibration acceleration;Through spectrum analysis,the peak value of tool vibration corresponding to the high-frequency part of cutting force is larger,the fluctuation of the high-frequency part of cutting force increases,and the corresponding vibration acceleration also increases.(3)By fitting the cutting test data,the tool vibration frequency is approximately represented by the chip sawtooth frequency,and the dynamic cutting force model is established through analysis;Considering the influence of cutting force change on tool system,a two-degree-of-freedom model of tool vibration system is established.