Research On The Key Technology Of Piezoelectric Ceramic Sensor For Cutting Force Detection

Metal cutting is widely used in modern machinery manufacturing industry.In the process of machining,the real-time wear condition of the cutter and the formation process of the workpiece surface can always be directly or indirectly reflected by measuring the change of cutting force.Whether the cutting force can be accurately detected and the cutting state can be sensed in real time directly affects the machining accuracy,machining efficiency and machining reliability of the machine tool cutting process.Therefore,the key to solve this problem is to design a set of intelligent cutting force measurement system which integrates micro piezoelectric ceramic sensor and machine tool tool.In this paper,according to the actual cutting force measurement needs,corresponding to the key technology for piezoelectric ceramic sensor is studied and a solution is proposed,which provides the theoretical basis and technical support for the follow-up realization of real-time accurate cutting force detection.This paper is mainly about the following aspects:(1)Design and make the piezoelectric ceramic sensor embedded in turning tool cushion.According to the actual lathe processing conditions,made a cutter-cushion piezoelectric ceramic sensor which can monitor the cutting force in real time,from the aspects of ceramic material selection,size design,process structure.The sensor follows the turning tool movement,perceives the change of cutting force in real time,realizes the integration of machining detection,and improves the detection accuracy and real-time performance of the measurement system.(2)Set up complete data acquisition system.A real-time data signal acquisition system based on piezoelectric ceramic sensor is constructed by combining the flexible NI Compact RIO software and hardware platform and the powerful Lab VIEW upper computer platform.Based on the actual acquisition needs,a set of software program for Compact RIO instrument acquisition system was written and data signal acquisition,storage,display and processing are realized.(3)Completed the static and dynamic calibration of the piezoelectric ceramic sensor.Using the established acquisition system and the method of weight loading and unloading experiment,the indicators of the static characteristics of the sensor are calibrated.The calibration results show that the sensor has high sensitivity and repeatability,but there is obvious hysteresis between input and output.The dynamic calibration test system is built and the natural frequency calibration of the new intelligent turning tool is completed.The calibration results show that the natural frequency of the tool is high,around 1827 Hz.(4)Completed the hysteresis modeling and compensation of piezoelectric ceramic sensor.Based on the hysteresis theory of a sensor,a model of a Duhem piezoelectric ceramic sensor is built.Based on the input and output data of the sensor,an improved gradient descent method based on learning rate was used to identify the model parameters.The hysteretic nonlinearity of the sensor is compensated by using the inverse model and series compensation method.(5)In the actual cutting experiment,the new intelligent turning tool with embedded tool cushion was installed on the lathe CA6140 by using the acquisition system built,and the output voltage of three orthogonal experiments was measured.The collected voltage data are imported into the inverse model to obtain the cutting force of the cutting experiment.