Experiment Research On Thermal Characteristics Of The Spindle System Based On Fiber Bragg Grating Sensors

Spindle unit is the core component of NC machine tool,whose thermal error directly affects the surface processing quality of workpiece.The main way to reduce thermal error is to compensate it.To compensate thermal error,the temperature field of spindle unit and the thermal offset of spindle tool tip must be obtained first.Among all components of the spindle unit,the spindle bearing is the most important.Its temperature field distribution and the change of its temperature rise are directly related to the thermal error of the spindle.At present,most of the sensors used to measure the temperature field of spindle support bearings are based on electrical sensors,which have some shortcomings,such as complex wiring,vulnerable to electromagnetic interference,poor stability and so on.Fiber Bragg Grating(FBG)Temperature Sensor has the characteristics of small size,anti-electromagnetic interference and corrosion resistance.Especially its grating has the function of multiplexing and can realize the distributed measurement of "one line and many points".Therefore,in this paper,based on FBG Temperature Sensor,the temperature field of spindle support bearing has been measured.The influence of spindle rotation speed,axial force and radial force on temperature field of spindle support bearing and thermal offset of spindle tool tip was investigated.Firstly,the power loss of the spindle bearing is calculated in detail,especially the spinning friction moment of the spindle bearing under the radial force.Based on ANSYS software,the temperature field and thermal deformation of the spindle unit under different working conditions are simulated.The influence law of spindle rotation speed,spindle axial force and radial force on spindle unit,especially the spindle support bearing,has been analyzed and obtained.And then influence of the spindle rotation speed,spindle axial force and radial force on thermal deformation of spindle tool tip has been obtained.Secondly,the test platform of spindle unit is built,and the temperature field monitoring system of spindle bearing based on distributed sensing of fiber Bragg grating is designed.Then the collection of temperature field data of support bearing under different working conditions has been completed and the temperature data in steady state has been compared with the simulation result,which verify the reliability and accuracy of the temperature field measurement method of spindle bearing.Then,the measurement system of radial thermal error of spindle tool tip based on laser displacement sensor is introduced,laser displacement sensor has been used to measure the radial thermal deformation of the spindle tool tip under different spindle rotation speed and different spindle axial and radial force.And the experiment results were compared with the simulation result,which verified the influence law of the spindle rotation speed,spindle axial force and radial force on the thermal deformation of spindle tool tip.Finally,the research results and problems in this paper were summarized and prospected.