Testing Techniques Of The Temperature Field Near Drilling Bit Based On Fiber Bragg Grating

In recent years, the drilling process is widely used in aerospace, automotive,electronics, medical equipment and other fields, hole processing account for about30%of the total machining. In metal drilling process, the drilling temperature is themain indexes to reflect the drilling performance. High drilling temperature will notonly affect the performance of tool and workpiece material, causing the wear andthe less service life of the drill, but also affect formation and size of bue whichchange the cutting force and the vibration of the drill, thus affecting the quality ofthe machined surface. However, drilling temperature measurement has been the hotand difficult research in the field of metal cutting. Traditional theoretical analysisalgorithm is very complex and the contact process is not easy to observe, usingdirect measurement method may also cause some damage to the drill and theworkpiece, and the experimental data is difficult to accurately measured. This thesisuse fiber Bragg grating to test the temperature of the vicinity of the drilling bit,connect finite element simulation software ANSYS/LS-DYNA to estimate thetemperature change of the drill. The main work of this thesis can be included intothe following aspects:1. This thesis study the theoretical basis of metal cutting heat generation andthe heat transfer, use the analytic method to solve the problem, come to theanalytical formula of drilling temperature. Introduce fiber Bragg grating sensingprinciple and the problem of temperature and stress cross sensitivity, use the sensorto measure drilling temperature field.2. This thesis use finite element analysis simulation software ANSYS to bulidthe finite element model of the metal drilling. Grid the model and enter LS-DYNAcalculator. Dynamic simulate the drilling process of twisted drill. Analysis andpredict the temperature and stress distribution of the workpiece in the drillingprocess. Compare the temperature distribution of different feed speed and rotationrate.3. This thesis use fiber Bragg grating as the temperature sensor to measure thetemperature distribution of the vicinity of the drilling bit. Firstly, microtubulespackage the fiber Bragg grating, exclude the impact of stress and strain on thesensor. Secondly, machine “Leadway450” use φ6drill, drilling140length and140 width square aluminum workpiece whose thickness is5mm and20mm, attachpackaged fiber Bragg grating to different points on workpiece. Real-timely monitorevery measurements point temperature during the drilling. Draw the picture ofmeasurements point versus time, at the same time by choosing between different Zshaft speed, different feeding speed, different workpiece material, compared theexperimental result with the simulation result, the relative error is about10%.Analysis the reason of error and outlook how to improve the accuracy of the system.