| The inner-diameter(ID)slicing technology is one of the main methods for slicing hard and brittle materials and it is widely used to cut and slice small-lot and multispecification products.The existing ID slicing technology has technical defects such as the rough surface of the slicing,waste of sawn material,and large workload of subsequent polishing and trimming,which greatly limits its further application and development.This article relies on the National Natural Science Foundation of China project "Ultrasonic vibration-assisted high-speed precision ID slicing coupling dynamics mechanism and application technology research",taking the ID slicing technology as the research subject.Beginning with the blade tensioning mechanism and blade dynamic characteristics during the slicing process,the theory and technology investigation of ultrasonic-assisted ID slicing of monocrystalline silicon is carried out.The main contents of this thesis are as follows:(1)Based on the theory of plate and shell mechanics,a nonlinear large-deformation model for the tensioning process of the ID slicing blade is established.The iterative algorithm of strongly nonlinear equations is used to solve the in-plane stress and lateral nonlinear deformation of the blade caused by tension,and then the blade stiffness and natural frequency of the blade are solved.The finite element simulation is used to verify the correctness of the theoretical model,and the influence of tension on the displacement,stiffness,and natural frequency of the ID saw blade is analyzed by using this model.(2)According to the heat transfer process in slicing,the heat transfer equation of the ID saw blade is established,and the heat distribution of the saw blade is calculated by the Fourier series expansion method.Considering the blade tension,heat distribution,and the interaction between the blade and the workpiece,a thermal-force-displacement coupling dynamic model of the ID saw blade is established.Based on this theoretical model,the influence of cutting parameters and blade parameters on blade vibration displacement,stiffness,and natural frequency are discussed.(3)Considering factors such as the dynamic characteristics of the ID saw blade,the structure of the ID slicing machine tool,and the applying direction of ultrasonic vibration,the structural layout of the ultrasonic vibrating device for ID slicing is completed.The initial dimensions of the transducer and the horn are determined based on the Timoshenko beam vibration theory,and the resonance frequency is optimized by the finite element method.Using the high sensitivity and frequency characteristics of the resonance acoustic emission sensor,the resonance frequency of the ultrasonic vibration device was measured.(4)Based on the theory of indentation fracture mechanics,the horizontal cutting force model in the process of ultrasonic-assisted ID slicing process is established.The theoretical cutting force model is verified by the monocrystalline silicon cutting experiment.The test results show that the cutting force calculated by the model is in good agreement with the tested cutting force.Finally,the cutting force model is used to analyze the influence of cutting parameters on cutting force.(5)A comparison experiment between ordinary machining and ultrasonic-assisted machining was designed,and the surface micromorphology of monocrystalline wafers was measured.The surface material removal mechanism of monocrystalline wafers is analyzed,and the influence of spindle speed and feed speed on the surface roughness of monocrystalline wafers is studied.The results show that the application of ultrasonic vibration during the ID slicing process can increase the ratio of the plastic material removal.Under the current experimental conditions,the value of the wafer surface roughness Sa is reduced by about 30% on average. |
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