Research On Vibration Characteristics Of Motorized Spindle Of Micro Drilling Machine Based On Laser Doppler Vibration Measurement Technology

With the rapid development of manufacturing industry,CNC machine tools are more intelligent and high-precision.At the same time,more and more functions of machine tool integration are required,which leads to more complex structure and higher reliability requirements.The motorized spindle is the core component of the machine tool.The vibration signal during its operation contains rich state information of the machine tool.The vibration characteristics of the machine tool can be obtained by vibration detection of the motorized spindle,so as to adjust the parameters of the machine tool to improve the performance of the machine tool.In addition,the vibration detection of the machine tool can pre-identify whether the running state of the machine tool is normal and prevent accidents of the machine tool.Therefore,the vibration detection of the motorized spindle of the machine tool is of great significance to improve the performance and life of the machine tool.At present,the contact sensor is generally used for the vibration detection of the motorized spindle of the machine tool.The sensor is installed on the spindle box during the measurement.The vibration signal obtained in this way cannot accurately represent the real vibration state of the motorized spindle.In addition,the research method of electric spindle fault identification is complicated at present,and the practical application of enterprises is difficult.The main work of this paper for the above problems is as follows:(1)In this paper,the laser Doppler vibration measurement technology is proposed as the measurement method of the vibration signal of the motorized spindle of the machine tool.The working principle of the laser Doppler vibration measurement technology to detect the vibration signal of the motorized spindle of the machine tool is introduced.The experimental platform is built with the VHS-250 high-precision micro-drilling machine motorized spindle as the research object.The experimental results show that the laser Doppler vibration measurement technology is very effective for the vibration detection of the motorized spindle,and it has certain guiding significance for the application of the laser Doppler vibration measurement technology in the vibration detection of the motorized spindle of the machine tool.(2)Taking the root mean square value of the vibration velocity signal of the motorized spindle as the index to measure the vibration intensity of the motorized spindle,the vibration intensity characteristics of the motorized spindle at different positions and different speeds during the operation of the machine tool are studied.According to the obtained law,the prediction model of motorized spindle vibration intensity is established by curve fitting method,and the validity of the prediction model is verified.The results show that the relative average error between the predicted value of the model and the measured value of the test is within 5 %.The prediction model can guide the selection of the rotational speed parameters of the micro drilling machine.(3)The frequency domain characteristics of the vibration velocity signal of the motorized spindle are analyzed,and the spectrum distribution law of the motorized spindle at different positions and different speeds is studied.The wavelet packet analysis method is used to analyze the energy distribution characteristics of each frequency band of the vibration signal at different speeds of the motorized spindle.The research shows that the energy distribution law of each frequency band of the vibration signal is basically consistent with the spectrum analysis results.According to the energy distribution characteristics of the vibration signal,the discriminant vector of the health state of the motorized spindle is constructed,and the health state detection method of the motorized spindle based on wavelet packet energy decomposition feature vector and Euclidean distance is proposed.The effectiveness of the method is verified.The method proposed in this paper has certain guiding significance for the health maintenance and fault detection of precision machine tools.