| SiCp/Al composites have excellent physical and mechanical properties such as high strength,low density,high temperature resistance and wear resistance,which are widely used in aerospace,national defense and military fields.However,due to the poor impact resistance,high brittleness,high strength and poor machinability of SiCp/Al composites,serious tool wear and even tool fracture are prone to occur in the machining process.Therefore,conquering its processing technology to improve the manufacturing base has an important impact and significance on improving China's national defense and military capabilities.Ultrasonic vibration assisted machining technology is a kind of non-traditional machining method for hard and brittle materials.Ultrasonic-assisted drilling is to add axial ultrasonic vibration to the tool on the basis of ordinary drilling.This machining method can significantly reduce the cutting force,improve the machining efficiency,and effectively reduce the surface roughness and improve the tool life.Therefore,it is considered as a new method for machining hard and brittle materials effective methods.However,the mature commercial ultrasonic machine tools are mainly imported from abroad,and the price is expensive.The exploration of ultrasonic machine tools in China is still in the primary stage.Therefore,the development of a stable and reliable ultrasonic-assisted machining system with excellent performance is of great significance for the realization of efficient cutting of hard and brittle materials and the improvement of China's manufacturing base.This article takes the ultrasonic-assisted drilling and processing device as the research object,and conducts experimental verification and research on the successfully developed device.The specific work content and research results are as follows:(1)Aiming at the problem of long overall length and high mechanical loss of traditional ultrasonic machining system,an integrated ultrasonic transducer with resonant frequency of 20 k Hz is designed according to the wave equation,and the modal analysis of the transducer is carried out by finite element simulation software.The resonant frequency of ultrasonic transducer is 20916 Hz,and the amplitude of transducer output can reach 14.2?m,which meets the processing requirements.(2)In view of the shortcomings of the power transmission mode of contact conductive slip ring in ultrasonic-assisted machining,a contactless power transmission device is designed,and the electromagnetic simulation of the relationship between the magnetic core structure and the coupling coefficient is carried out.The coupling coefficients of primary and secondary coils under different air gaps are measured to verify the correctness of the simulation results.(3)In order to improve the power transfer efficiency of contactless power transmission device and eliminate the reactive power loss in the circuit,based on the equivalent circuit model of ultrasonic transducer and the mutual inductance model of contactless power transmission device,the compensation design of the primary and secondary side circuit is carried out.Four kinds of circuit compensation methods are proposed and the calculation formula of compensation elements is derived.The experiment shows that the primary circuit after compensation reaches resonance state,and the power transfer efficiency is significantly improved.(4)In order to verify the drilling performance of the developed ultrasonic-assisted drilling device,the comparative experiments between ultrasonic-assisted drilling and traditional drilling are carried out.The results show that the axial force and surface roughness of the hole produced by ultrasonic-assisted drilling are significantly less than those of traditional drilling.(5)The orthogonal experiment of ultrasonic-assisted drilling is designed,and the primary and secondary factors affecting the axial force are obtained after the research,and the optimal cutting parameters combination of ultrasonic-assisted drilling is obtained. |
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