Study On Longitudinal-torsional Resonance Rotary Ultrasonic Machining Of Carbon Fiber Composites

Carbon fiber reinforced composites (CFRP) are now widely used in aerospace industry,transport, sports equipment, textiles, medicine and other fields. Due to the special structure andphysical properties of CFRP, the traditional processing methods can not meet its processingneeds. And rotary ultrasonic machining has a strong technological advantage, can well solve theproblems of parts processing of difficult processing materials, improve the machining efficiencyand surface quality. But now a lot of ultrasonic machining mode uses a single longitudinalvibration mode. The required processing speed is high. The surface of the fiber materialprocessing section will appear glitches, stratification, pits and other defects. The tool exist acertain amount of wear, and need higher requirements of grinding abrasive. The quality of theinner wall surface of the peripheral milling and holes machining is poorer. These limit itsprocessing fields and forms.Based on "the longitudinal-torsional resonance rotary ultrasonic machining of carbon fibercomposites research" as the subject, the dissertation thoroughly studies the key issues of thelongitudinal-torsional resonance rotary ultrasonic machining system and milling compositesfrom the theoretical and experimental aspects. Its main contents and results are as follows:(1) Introduction the research status of CFRP processing and ultrasonic machiningtechnology, analyze the deficiencies. Design ultrasonic transducer vibrator and chute vibrationrod, and do modal analysis, optimize its structure size, improve the output amplitude of torsionalvibration.(2) According to the theory of design of sandwich transducer, the modal simulation oftransducer without bolt and with two kinds of different materials of bolt are done by the finiteelement software, use impedance tester to test end analysis related vibration characteristics oftransducer. And select appropriate materials bolt to pre-tightening of transducer.(3) On the basis of the metal cutting theory and impact characteristics of ultrasonic vibrationcutting, a simple geometric model between the tool and the workpiece is built according to thehydrodynamic lubrication theory and the tribology principle. Derive the hydrodynamic pressureequations of rake face and flank face through the simple model, and analysis the influences ofthe hydrodynamic pressure oil film on the surface of the machined workpiece and tool. Thehydrodynamic pressure mechanism of periodic intermittent micro cutting process under theultrasonic vibration machining carbon fiber and the causes of harms about the continue processing after tool wear are researched. Ultrasonic vibration machining experiment areresearched.(4) Through the establishment of ultrasonic face milling of CFRP model to analyze themilling mechanism of CFRP under two kinds of angle. Experimental research was carried out inboth longitudinal-torsional resonance rotary ultrasonic face milling and traditional face millingof CFRP. Compare to ultrasonic cutting mechanism and ordinary cutting mechanism of CFRPunder different angles. Analysis the reasons to improve the surface quality and reduce the toolwear under the ultrasonic cutting. The contrast tests about longitudinal-torsional resonance rotaryultrasonic milling and common milling of CFRP are carried on.(5) Process test research about longitudinal-torsional resonance rotary ultrasonic milling ofCFRP is carried on. Experimental study includes the orthogonal experiment of end milling andperipheral milling, the influence of the cutting fluid for ultrasonic milling effects and comparisonof ultrasonic milling under different cutting angles.