Study On Ultrasonic Cutting Mechanism On Straight Blade Cutter Of NOMEX Honeycomb Composites

The NOMEX honeycomb composites sandwich plate structure is widely used in aviation andaerospace fields as NOMEX honeycomb core for series of excellent merits such as high specificstrength, high stiffness, corrosion resistance, good insulation properties and good vibrationabsorbing. The NOMEX honeycomb composites is a typical difficult-to-machine fiber materials.For traditional high speed milling, the finished surface of honeycomb composite is easy to appearphenomenon such as matrix cracking, burr, appearance defects, these defects and damage greatlydegrade performance of the structure component, which is very hardly to meet processingrequirement in aviation and aerospace fields. Aiming at the problems of traditional milling,domestic start introducing ultrasonic vibration cutting technology in recent years, at present theresearch on ultrasonic cutting composite material is still in primary stage because of ultrasoniccutting technology started lately in domestic. The research on processing of honeycomb core partshas focused on the milling processing principle and processing technology, has not formed systemtheory model and mechanism, the ultrasonic cutting of honeycomb composite has not beensystematically research from processing mechanism to processing technology, which is lack oftheory guidance, so that ultrasonic cutting of honeycomb composites has been not realized withhigh efficiency and high quality, which to some extents the honeycomb composites is limited to usein aerospace field. For these problems, the paper takes NOMEX honeycomb composites ultrasoniccutting on straight blade cutter as the research object, research on mechanism of ultrasonic cuttingand processing parameters optimization were carried on，and main research content and researchresults are as follows:(1) At present the mechanism theoretical system has been not yet formed perfectly forNOMEX honeycomb composite ultrasonic cutting, aiming at these problems, based on analysis oftool’s kinematics characteristic, fracture mechanics of ultrasonic cutting honeycomb compositeswas studied on dynamic fracture theory, research results show the internal cracks of materialrapidly expand caused by ultrasonic vibration, which make the material with advance microfracture, thus reduce the cutting force. On the basis, cutting force relational model among cuttingparameters, tool’s structure parameters and cutting force was presented and founded, and lays agood foundation for further parameter optimization.(2) Aiming at the problems in current that the selection of process parameters with blindly andmachining quality and machining efficiency with undesirability, the experimental research on cutting force of NOMEX honeycomb composite were carried on with ultrasonic cutting andwithout ultrasonic cutting. The research results show that compared with the ordinary cuttingmachining, ultrasonic vibration cutting processing can effectively reduce the cutting force, and canget better surface quality, which has prominent advantages; the influence laws of single cuttingparameters or two interaction factors for cutting force were summarized, the results show what therational choice of swinging Angle, top Angle of cutting tool, and cutting depth is the vitalsignificance to reduce cutting force and improve surface quality of parts; and the research resultsshow the correctness of cutting force theory model is well verified.(3)Aiming at the problems that the process parameters how to reasonable choice has not beenvery good to solve in ultrasonic cutting, this paper embarks from improvement of machiningefficiency and machining quality, optimized objective function was found, which took cutting forceand the material removal rate as the optimization goal, and cutting parameters optimizationresearch was carried on, the optimization algorithms which combined local search ability ofnonlinear programming algorithm with global search ability of genetic algorithm was used to theoptimization of cutting parameters calculation to obtain the best process parameters. Theoptimization results show that optimization results of process parameters is consistent with thetheoretical analysis results, so that the correctness of the optimization results are verified, andprovides a certain reference value for the selection of process parameters for NOMEX honeycombcomposites with ultrasonic cutting in actual machining.