Research On Grit Wear Process And Monitoring Technique Of Grain Wear In Single-grit Grinding

Grinding with tools,which makes use of special arrays of abrasive grits or regular micro-cutting edges aroused wide concern as it provides high grinding performance.How-ever,it was found that the newly developed grinding tools were limited by grain wear though it was superior in wear resistance when compared to conventional grinding wheels.To alleviate the wear affection and improve the capability of the grinding tools,this thesis focused on the problem of grain wear,and researched on the material removal mechanism,wear behavior and geometry evaluation during single grit grinding process.And based on the AE technology,the features of abrasive wear were extracted,the results were combined with the worn geometry to study the method of monitoring of the grit wear form.Several efforts have been achieved concentrating around these specific themes and list as follows:Chapter 1:Scientific backgrounds and state-of-art concerning this field are compre-hensively elaborated,the structure and contents of this thesis are depicted at the end of this chapter.Chapter2:In order to make the geometric model in single grit grinding more realistic,the true micro-morphology of the PCBN grit was used to construct the finite element model of grinding AISI 4340,and the grinding force,grinding energy and scratching profile were calculated,the grinding test was conducted to validate the accuracy of the simulated results.Chapter3:Aiming at the several wear forms of PCBN grit during the grinding pro-cess,wear tests were conducted to study the geometry evolution during the grinding pro-cess and the geometry was further evaluated based on the fractal theory,the wear forms were induced according to the worn geometry,the relationship between worn geometry and grinding force and wear form was analyzed,the grinding force and scratching profile were simulated according to the worn geometry and the results were used to illustrate the main wear form and its reason.Chapter4:The correlation between AE features and grit wear was studied,the cor-relation between worn geometry and AE waveform was analyzed,aiming at the issues of grinding burn and macro-fracture caused by abrasive wear,the single grit grinding experi-ment was conducted to investigate the AE features of attrition wear using a pair of sharp and blunt grits.The AE features were extracted in both time and frequency domain.Discredit wavelet decomposition was used to make a further research on the difference between the sharp and blunt grits and the main AE sources were identified.Chapter 5:The AE features were extracted according to the correlation research,the features including AE counts,RMS value and energy proportion at certain frequency band were extracted and the effectiveness of these features was validated,the signals during the wear process were differentiated using the least square method to realize the monitoring of grit wear.Chapter 6:The grit wear condition was refined using the self-organized map(SOM)clustering method,the random forest method was introduced as the classifier,based on the above research,the monitoring system of grain wear for single grit grinding process based on AE technology was studied,including demand analysis,frame construction,hardware design and selection and workflow design,the accuracy of recognition of the system was tested with the experiment data.