Study On Ultrasonic Vibration Turning Of C/C Composite

C/C composite which is reinforced by carbon fiber bases on carbon matrix. It has a series of excellent performance, such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance, fatigue tolerance, creep resistance, electrical conductivity, heat transfer and small expansion coefficient. So it can not only be a structural material bearing heavy loads, but also play a role as functional materials.C/C composite has a wide range of applications in the aerospace field. It is very difficult to process for its high hardness, high strength, anisotropy, poor thermal conductivity and can not be liquid-cooled. However, many large structures need precision machining. There are many disadvantages in common turning, such as low accuracy, low efficiency, serious tool wear and high cost. So it is difficult for common turning to meet the processing needs now.Ultrasonic vibration machining has solved many critical technological problems of materials that are difficult to machine, and achieved good results. This paper studied on ultrasonic vibration turning of C/C Composite, mainly conducted in the following areas:Firstly, this paper designed and developed the ultrasonic vibration system, selected a reasonable tool parameters. And then connecting mechanism between the ultrasonic vibration system and the machine body was designed to ensure that the entire system had appropriate levels of stiffness and accuracy after assembly. The tip amplitude was measured and calibrated when the system was in the resonance state.Secondly, the evaluation program of surface quality was determined by analyzing the surface characteristics of C/C composite after turning machining. Contrast experiments were carried out in which C/C composite were machined by common turning and ultrasonic vibration turning with different cutting tools (PCD, CBN, KW10) and different processing parameters. Through the contrast experiments, typical surface one was choosed as the processing quality evalution suface and PCD cutter was proved to be the best choice under the same parameters. Using the best tool, the cutting force, cutting temperature and tool wear which were produced by common turning and ultrasonic vibration turning were compared and analyzed. And the comparison results showed that: Compared with common turning, ultrasonic vibration turning has obvious advantages.Finally, the influence law of cutting speed, feed rate and amplitude to workpiece surface quality of C/C composite were analyzed and researched. Then the optimized matching relationship of the ultrasonic parameter (amplitude) and machining parameters (cutting speed, feed rate, cutting depth, etc.) were explored through multi-factors orthogonal experiments. At last, a reasonable processing technology of ultrasonic vibration turning of C/C Composite was given, and it was verified by experiments.Compared with common turning, ultrasonic vibration turning greatly improves surface finish quality of C/C composite, reduced cutting temperature, cutting force and tool wear. And it is advantageous to turning C/C composite with a high precision, a high efficiency, and a low cost.