Research On The Ultrasonic Milling Mechanism Of C/C Composites

With the improvement of comprehensive national strength, all walks of life putforward higher performance requirements on the material, and C/C composite is a kindof new composite materials developed in the context. It has many excellent physical andmechanical properties such as high specific strength and specific modulus, hightemperature resistant, wear resistance, small thermal expansion coefficient and gooddimensional stability. The reinforcement, carbon fiber, can be produced in largeamounts by the traditional process and it has many other advantages such as low cost,anisotropy, low manufacturing costs and so on. For the above reasons, it is widely usedin aerospace, electronics, automotive, advanced weapons systems, petrochemical,environmental engineering, energy, transportation, construction, sports equipment,instrumentation, machinery manufacturing and the nuclear industry.The reinforcement of C/C composite is carbon fiber which has high strength andhardness, and the bonding interface between carbon fiber and carbon matrix has lowerstrength where it is easy to produce defects in the processing. So it makes themechanical processing of materials difficult, the tool wear is severe, the surface texturequality of parts is poor and the processing efficiency is very low. Therefore, theprecision machining technology of C/C composite has become a major scientificchallenge faced by the research and application of composite materials.For the problem of difficult machining of C/C composite, based on the ultrasonicvibration machining technology theory, its advantages are used to improve theprocessing defect in the normal processing and the nice texture surface quality of theworkpiece is obtained in this paper. The ultrasonic vibration milling device wasdesigned which can meet the processing requirements. The theoretical model of cuttingforce was established under the conditions of ultrasonic vibration milling. The millingtests of C/C composite were conducted under the conditions of ordinary cutting,one-dimensional ultrasonic vibration and two-dimensional ultrasonic vibration. Theresults show that, the cutting force is small, the surface texture quality is good and thetool wear is small in different milling parameters when it is under ultrasonic milling. For the microstructure of surface texture quality, the relationship between the surfacetexture quality and friction wear was analyzed, and a lot of analysis on the surfacetexture quality and surface micro-cracks were conducted. The milling force was largelyinfluenced by the cutting angles between tool and fasciculus of the material, thussurface texture quality and tool wear conditions were influenced. According to theprocessing conditions, the model of tool wear rate was established. Through thecorrelative experiments, the tool failure forms and tool wear mechanism were verifiedand discussed which laid the theoretical foundation for the subsequent experiments.