Research On The Key Technologies About Smart Cutting Tool System Based On Surface Acoustic Wave Techniques

During machining process, the status monitoring and control of the cutting tools isessential for the obtaining of high surface quality and integrated high surface accuracyof the components. Cutting force is an important comprising factor of processing status,which affects directly the cutting temperature, tool wear, and power consumption, and atthe same time, provides processing parameters for self-adapting machining. However,there are common disadvantages for current cutting force measuring instruments, suchas low dynamic characteristics, bad environmental adaptability and high cost, thusdifficult to be widely used in industrial processing conditions. Consequently, it is ofsignificance to conduct research on the cutting force measuring apparatuses which havegood dynamic characteristics, low cost and can be widely used in industrial processingconditions. The Surface Acoustic Wave (SAW) techniques is a hotspot in measuringfield, and if applied in processing measuring, could show great advantages, such assmall size, good dynamic measuring characteristics, can achieve wireless measuring,good environmental adaptability and low-cost, etc. This project focuses on the keytechnologies of strain sensitive mechanism, cutting force identification and smart tooldesign for the cutting force measuring smart cutting tool based on surface acoustic wavetechniques, and integrate surface acoustic wave resonator on normal cutting tool, canachieve real-time measuring of the main cutting force during processing, and can adaptto complex machining environment.Introduced the considerations when choose the piezoelectric substrate materials,analyzed the SAW excitation mechanism by the Inter-digital Transducer (IDT) and theparameters design considerations. Analyzed the strain sensitive mechanism of thesurface acoustic wave resonator (SAWR), and deduced the simplified relation betweenpiezoelectric substrate strain and SAWR response frequency based on the strainmeasuring mechanism.Analyzed the resonant frequency of the surface acoustic wave resonator. Solved theCoupling-of-Mode (COM) equation by introducing P-matrix to the COM theory, anddeduced the conductance and Insertion Loss, and obtained the resonant frequency of theSAWR. The calculated resonance frequency and insertion loss coincide with experimentmeasuring result.Based on the strain and temperature sensitive characteristics of the SAWR, sticktwo SAWRs on the upper and lower surfaced of the CNC cutting tool bar using Epoxybinder, and obtained the smart cutting tool design scheme which can measure cuttingforce and exclude the disturbing of cutting temperature, and analyzed force signalidentification method. Deduced the theoretical relation between cutting force and quartzsubstrate strain which is verified by finite element simulation, and the relation shows that the influence of the sticking position to the measuring sensitivity is ignorable, thusthe SAWR should stick near the tool head to improve the cutting tool stiffness. Based onthe influence of the quartz substrate strain to the surface acoustic wave length and speedin COM theory, obtained the linear relation between cutting force and frequency shift ofthe SAWR, which provides theoretical basis to the force signal identification.Calibrated the smart tool by applying static force to cutting edge, and obtained thecutting force and frequency shift relation which coincide with theoretical calculation,which shows that the measuring sensitivity of the smart tool is-40Hz/N. Dynamiccutting force measuring in processing shows that the smart tool which based on surfaceacoustic wave techniques can achieve the real-time measuring of cutting force.