Development Of Online Monitoring System For Vibration-Assisted Cold Extrusion Processing Of Trapezoidal Thread

Trapezoidal threaded connection has super manufacturability,high root intensity,good neutrality and good sealing.Therefore,it has wide application prospect.This paper took a new type of trapezoidal thread vibration-assisted cold extrusion processing method as the research object,and established a dedicated on-line monitoring system for machine tools based on virtual instrument technology.From the perspective of the signal,the effect of assisted-vibration of vibrating device in the process of trapezoidal thread cold extruding,and the technological test with the material of 316 L stainless steel were analyzed.It provides a theoretical and practical basis for the selection of extrusion process parameters and further improvement of machine tool.The main research contents and achievements are as follows:1.The on-line monitoring system for the vibration assisted cold extrusion process of trapezoidal threaded is established based on virtual instrument technology.By acoustic emission sensor,acceleration sensor,resistance strain gauge,infrared temperature sensor and the corresponding signal modulator,sending the signals to the LabVIEW software via PCI or serial,these signals’ filtration,acquisition,display and storage was realized.2.The signal analysis theory and the implementation of MATLAB program are introduced.The pretreatment and feature extraction of sensor signal are carried out.For acoustic emission signal and vibration signal,through analyses of time domain,frequency domain and wavelet packet,the root mean square value of the two is extracted as time-domain eigenvalue,peak frequency is the frequency-domain eigenvalue,and the energy spectrum of each layer is the wavelet packet eigenvalue.For torque signal and temperature signal,through analysis of time domain,the average of phase Ⅲ is extracted as timedomain eigenvalue.3.The effect of assisted-vibration of vibrating device in the process of trapezoidal thread cold extruding is analyzed.On the one hand,by analyzing the change of the angle amplitude of the tap in the process,and the influence of spindle speed and excitation frequency on its change,explored the positive effect of the assisted-vibration.On the other hand,by analyzing the change of the peak frequency of vibration and acoustic emission in three different working conditions of machine tool,the negative effect of the assisted-vibration was explored.4.The processing of vibration assisted cold extrusion processing of trapezoidal thread is studied.From the perspective of the mechanism of acoustic emission,vibration,torque and temperature,considering the change of these eigenvalues,the influence of spindle speed,excitation frequency and lubricating type on these three extrusion process parameters is analyzed.It provides practical basis for the selection of extrusion process parameters.