Research on Multi-sensor Integrated Smart Tool Holder for Cutting Process Online Monitoring

Author:Jie Zheng You

Supervisor:li jian guang lu yong


Degree Year:2019





Intelligent manufacturing is the main direction of “Made in China 2025” plan,and the development of intelligent products and equipment for intelligent manufacturing is one of the important strategic measures.For manufacturing companies,intelligent sensing devices can provide multi-parameter information for cutting process monitoring,which is an important basis for achieving production automation,improving processing efficiency and product quality,and reducing production costs.Therefore,research on intelligent sensing device design and monitoring technology to meet application requirements is of great significance and application prospect for promoting the development of intelligent manufacturing technology.Aiming at the multi-parameter information detection requirements of the cutting process and the shortcomings of the current sensing equipment,this paper has carried out research on the multi-sensor integrated smart tool holder,and developed a wireless intelligent tool holder that can realize the multi-dimensional cutting force and cutting vibration simultaneous measurement in the cutting process,then based on which research on tool condition monitoring has been done.Aiming at the cutting force and vibration detection requirements in the milling process,the smart tool holder multi-parameter information sensing overall scheme is designed,including the multi-dimensional force measurement scheme based on capacitive displacement sensor and the vibration measurement scheme based on directly embedding the commercial accelerometer.A capacitive multi-dimensional force/torque sensing structure with low cross talk is designed,and a four-direction force decoupling equation is established.By designing multiple sets of deformed beams on the standard CNC tool holder,the force in each direction can be calculated reliably by the small deformations of six positions of the deformed beams.By establishling the force model of the sensing structure,the influence of different structural parameters on the deformation sensitivity is analyzed,and the various structural parameters are optimized and determined.The static and dynamic characteristics of the tool holder structure under this parameter are analyzed by finite element software,and the analysis results show that the designed tool holder meets the application requirements,which establishs the foundation of smart tool holder multi-parameter signal perception.In order to realize multi-parameter signal sensing and acquisition,the design research of smart tool holder sensing unit and multi-parameter information acquisition system is carried out.A parallel plate type capacitive micro-displacement sensor is designed to measure the small deformation of the beam structure,so as to realize the force detection.The key parameters of the capacitive sensor are designed and the capacitor plates assembly scheme is determined.Then,the influence of the capacitor plates assembly error on the sensitivity is analyzed.Based on the capacitance digital conversion chip and acceleration chip,a multi-dimensional force and vibration sensing unit with high sensitivity and low power consumption is designed,and the multi-parameter signal acquisition and wireless transmission system are developed and tested.The test results show that the designed acquisition system meets the application requirements and can realize the smart tool holder real-time accurate collecting multi-parameter information.On the basis of completing the multi-parameter information sensing tool holder structure and the sensing unit and acquisition system design,a multi-sensor integrated smart tool holder is developed.In order to evaluate the comprehensive performance of the developed smart tool holder,the experimental research on the static and dynamic performance of the tool holder is designed and conducted,and the various static and dynamic characteristics,such as sensitivity,cross talk and natural frequency,etc.are determined.Meanwhile,the milling experiment is designed and carried out to evaluate its multi-parameter information acquisition performance in actual cutting by comparison with standard sensors.The experimental results show that the smart tool holder can accurately and reliably measure the three-dimensional cutting force,torque and cutting vibration information during the cutting process,which provides a guarantee for the practical application.Research on tool condition monitoring(TCM)technology is conducted based on the developed multi-sensor integrated intelligent tool holder.By analyzing and processing the experimental data of tool wear under different cutting parameters,the time domain and wavelet domain features of the signal are extracted,and the feature set which is strongly related to tool wear state is selected based on Fisher Discriminant Ratio.A hidden Markov tool wear state identification model based on multi-source signal feature fusion is established,and the recognition ability of different characteristics for different tool states is analyzed.A method for identifying tool wear state by combining two sets of feature sets is presented,which improves the accuracy of tool wear state identification.LabVIEW and Matlab software are used to jointly develop the TCM software system.The real-time acquisition of multi-dimensional force and vibration signals in the cutting process,online monitoring of tool wear states and data offline analysis,etc.have been realized,which expands the application scene of multi-sensor integrated smart tool holder.