Research On Rotary Piezoelectric Dynamometer Based On Wireless Transmission

With the rapid integration of information technology and industry,it has greatly stimulated the development potential of industrial intelligence.The development of industrial intelligence is inseparable from the development of intelligent equipment.Intelligent equipment should contain intelligent components of"thought".In the field of torque testing,high-precision machining generally places higher requirements on the real-time monitoring system of cutting forces.Traditionally,the dynamometer is generally placed on the workbench.This monitoring method restricts the development of real-time monitoring systems by the structure and size of the dynamometer.And the small size but wide monitoring range of intelligent dynamometer can not only effectively solve the traditional problem of multiple wiring harnesses,chaos,and clutter,but also has the characteristics of simple operation and low cost.Piezoelectric sensors are widely concerned and applied in the field of torque testing due to their high stiffness,high natural frequency,and high sensitivity.Traditionally,a charge amplifier with a high input impedance is used as a signal processing part,but these amplifiers are large and difficult to directly put into a small rotary dynamometer.Therefore,it is necessary to design a quasi-static charge amplifier circuit and a microcontroller-controlled wireless transmission circuit as a signal processing part to be placed inside the rotary dynamometer.This paper designs a rotary piezoelectric force gauge with small volume,multiple support points,and high precision,which can realize real-time monitoring of cutting force.The main research contents are as follows:1)The piezoelectric force sensor is designed based on the calculation result of the wafer size.By analyzing and comparing the multi-point arrangement of sensors,selecting an appropriate arrangement scheme and establishing an equivalent mathematical model,and analyze the axial force F_Z,tangential force F_t,radial force F_r and axial torque Mz,where the axial torque is obtained in the form of"force×force arm";2)Combined with the analysis scheme,the equivalent three-dimensional model of the piezoelectric force measuring instrument is established,and the rationality of the design dimension is verified.The static simulation analysis of the three-dimensional model is carried out through ANSYS simulation technology to study the problems that may occur under various actual working conditions,complete the structural optimization of the force measuring instrument,and provide good data support for the dynamic balance through the modal and harmonic response analysis;3)An insulated gate field effect tube is used to form a pre-differential amplifier circuit to increase the input impedance of the quasi-static charge amplifier circuit.And analyze the charge amplifier stage in theory and simulation.Circuit,second-order filter circuit,sensitivity adjustment circuit,output power amplifier circuit.Based on the STM32 single-chip microcomputer,the acquisition and transmission module circuit is built,including A/D conversion circuit and Bluetooth wireless sending and receiving circuit,so as to realize A/D conversion,LCD data display,SD Card storage,over-voltage alarm and other functions;4)Non-linear error,accuracy and repeatability comparison experiments are performed on the static charge amplifier circuit.After the integrated circuit is placed in the dynamometer to complete the assembly,static and dynamic calibration experiments are performed on the designed rotary piezoelectric dynamometer.The non-linear error of the dynamometer designed in this paper is less than 2%,and the repeatability is 3%.Meet the requirements for the real-time monitoring of tools.