| The temperature in the process of bone drilling is one of the most important indicators of orthopedic surgery.Through the transient temperature monitoring of the bone drilling process,the specific situation of the bone drilling process can be well understood,so it is of great significance for the monitoring of bone drilling.Aiming at the technical problem that the temperature of bone drilling is difficult to measure in orthopedic surgery,this paper developed an in-situ temperature measuring tool for bone drilling based on thin film thermocouples,which is used to measure the temperature of bone drilling in situ.The specific research contents are as follows:The 3D modeling of the tool and the workpiece was carried out by using CREO software,and imported into the ABAQUS finite element simulation software for thermal coupling analysis of the bone drilling process,and the highest temperature position of the drill bit during the bone drilling process was obtained.According to the finite element simulation results,an in-situ temperature measuring tool for bone drilling based on thin-film thermocouples is designed.The thin-film thermocouples have a vertical relationship with the flank surface,so that they can not only measure the highest temperature in the drilling process,but also overcome the In the process of processing,the thin-film thermocouple is easy to be worn,and the ceramic sintering technology is used to solve the problems of the traditional lead and thin film connection method that the electrode wire is easy to fall off and the volume is large.A special jig and mask for the preparation of thin films that can hold 5 blades at one time are designed,and a thin-film thermocouple temperature sensor is integrated on the drill bit by magnetron sputtering technology,which greatly improves the preparation efficiency.The morphology of each part of the film was characterized by SEM,EDS and step meter.The test results showed that the surface of each film had good compactness and continuity,no obvious defects,and the ratio of the film composition and the prepared target composition was close.According to the actual temperature measurement range of bone drilling,the developed sensor was statically and dynamically calibrated from room temperature to 105°C.The results show that the sensor Seebeck coefficient is 40.65μV/°C,the sensor linearity is 0.204%,and the linear fitting The coefficient reaches more than 0.999,and the maximumrepeatability error of 6 measurements is only 3.96%.The data shows that the developed sensor still guarantees good repeatability and measurement accuracy under a wide range.The dynamic response time of the sensor is 2.307μs,and the response speed is fast,which can meet the temperature transient test requirements of bone drilling.Finally,a full-factor test scheme based on drilling speed,drilling depth and feed rate was designed,and the in-situ temperature measurement tool for bone drilling based on thin film thermocouple was applied to the temperature measurement test of bone drilling.The co-rotating cage of the tool holder is combined with the Zig Bee wireless temperature test unit developed by the research group,which effectively suppresses the clutter interference caused by vibration and shock,and obtains a real-time temperature curve without clutter interference during bone drilling.According to the test results and comprehensive comparison,it is found that among the three factors,the drilling depth has the greatest influence on the bone drilling temperature,followed by the rotational speed,and the feed rate has the smallest influence.According to the experimental data of bone drilling temperature,the prediction formula of the maximum drilling temperature was established,and the accuracy of the prediction results was verified by experiments,which provided important guiding significance for the closed-loop control system of orthopedic robot for bone drilling operation. |
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