Research On The Key Technologies About Cutting Tool With Intelligent Transient Temperature Measuring System

Heat accumulation is an important physical phenomenon in the process of cutting and cutting temperature directly affects machining quality.The machining error caused by the cutting temperature has become one of the most important factors that affect and restrict the precision and quality of workpiece.At present,traditional method for cutting temperature measurement has insufficient of long responds time and hard wiring that it can’t quickly and accurately measure the true temperature.Real time monitoring of transient temperature in thin-walled parts and precision ultra-precision machining has become a technical problem in the field of modern machining.Aiming at the above problems,a smart cutting tool based on NiCr/NiSi thin-film thermocouple for transient temperature measuring has been prepared in this article.The transient cutting temperature automatic detection system is integrated with the cutter arbor,which utilizes embedded microprocessor as main controller.The prepared smart temperature measuring cutting tool has the functions of data acquisition,data processing and data storage.In this paper,the overall scheme of design and manufacturing method of temperature measuring blade embedded with thin film thermocouple were firstly proposed.Special polishing mold,mask and stage of temperature measuring blade were developed.The preparation of SiO₂thin film and NiCr/NiSi grade thermoelectric thin film were gotten by pulsed DC magnetron sputtering technique.By changing the RF power,technical method of multiple deposition was adopted to prepare SiO2 insulating thin film,which has the characteristics of densification,pinhole-free structure and correct chemical ratio.The insulation resistance reached 9.5×10¹²?.What’s more,the lead connection method was studied and a NiCr/NiSi thin film thermocouple wire blade clamping mechanism was developed,which can solve the problem that it causes instability of connection and electronic performance when using traditional method to connect thermoelectric film with compensation wire.The static calibration method of thin film thermocouple of temperature measuring cutting tool tip that adopted oil to separate thermo junction from compensate wire was studied,which avoided the calibration error due to compensation wire and thermal junction located at the same temperature field in traditional calibration process.The static and dynamic calibrations of NiCr-NiSi film thermocouple were carried out in the self-developed automatic calibration system.Seebeck coefficient has good linearity of 40.5μV/K.In the range of 30 to 300℃,the maximum linearity error was less than 0.92%with the characteristics of stability and quick response time of0.083 ms.Design of intelligent monitoring system for smart temperature measuring cutting tool is proposed.The host computer temperature monitoring software and temperature measuring unit capable of being embedded in tool cutter bar were developed to realize the function of cutting temperature data automatic acquisition,processing,storage,wireless transmission,format conversion and real-time display.Performance test results showed that the maximum error of system was less than±0.16℃,the sampling rate was up to 24S/s and the dynamic response time is0.1s,which could achieve real-time monitoring of the transient temperature of cutting zone.The manufacturing and field cutting and signal transmission experiments test of smart temperature measuring tool was completed,which showed that the prepared cutting tool with smart transient temperature measuring system could quickly and accurately detect the change of transient cutting temperature within 0.1s and provide a new way for the research and development of smart temperature measuring tools.