Key Engineering Materials Vol. 568

Abstract: Based on the Kinematic analysis, the indentation fracture mechanics is used to build a force model of ultrasonic vibration mill-grinding. To verify the force model, experiments are carried out for silicon nitride ceramics with various machining parameters, meanwhile grinding forces are measured. Finally, comparison between predicted results with experimental results is presented.

Abstract: The corrosion property of the cast manganese steel by shock excitation and rotation method was done by the corrosion experiment. The experiment showed the corrosion resistance of the cast manganese steel by shock excitation and rotation method was better than that of the cast manganese steel by traditional casting technology. In addition, the experiment results showed that corrosion weightlessness was increased with the time increasing. In twenty-four hours, the corrosion of the casting manganese steel could not very serious with the time increasing, but exceeding twenty-four hours, the corrosion degree of the casting manganese steel would increase with the time increasing.

Abstract: SiCp/Al thin-walled structure is processed by rotary ultrasonic machining (RUM). Machining allowance of thin-walled structure is large, manufacturability is bad, and it is vulnerable to vibration to reduce processing quality in machining. Based on analysis of chatter mechanism of RUM, a dynamic model for chatter analyzing and a stability judgment criterion are established and the simulation is conducted for a typical thin-walled component of SiCp/Al composite with time domain analysis method. The simulation results show that machining parameters of RUM could be optimized selected with this model, chatter could be prevented effectively and a good processing effect achieved.

Abstract: The impact experiment of the joining workpiece of the friction stir jointing for 7022 aluminum alloy was made by the impact load experiment machine. The objective was studying the effect of the different joining process parameters of the FSJ on impact toughness. The results showed the impact toughness of the joining region was lower than that of the base metal when the rotation speed of the tool was 300rpm and the feed speed was 30 and 50mm•min-1, the impact toughness of the joining region of the other joining process parameters was higher than that of the base metal. The impact toughness of the joining region was the best when the rotation speed of the tool was 400rpm and the feed speed was 100mm•min-1. It is higher than 22.3% of the base metal. The impact fracture of the joining region was mainly dimple; only fracture edge appeared a small amount of the quasi cleavage. The fracture presented good toughness.

Abstract: To design the flow field of inner-spraying cathode in NC-ECT, the numerical model was built according to the physical model of the cathode flow channel, and the Computational Fluid Dynamics (CFD) method was applied to solve the numerical model. The velocity and pressure distributions were obtained. The influences of the cathode internal structure on the flow field were analyzed according to the numerical simulation. The relatively good simulation results were obtained by means of the optimization design of the cathode internal structure. Based on the experiment, the accuracy of simulation was verified, and the correction number of the flow field design was reduced in NC-ECT. It is indicated that the CFD method can be applied to guide the optimization design of the cathode structure.

Abstract: For 45steel, the noise test of different groove milling inserts in milling processing is carried on and the distribution model is studied. Firstly, the cutting noise test system is designed and the acquisition scheme of the test points is determined; secondly, the noise tests in the dry milling process are carried on and the test results are analyzed. Also the influence degree of different milling parameters on the noise of milling inserts is analyzed and the distribution situation of the noise size with different milling parameters is compared; finally, using stepwise regression analysis method, the milling noise distribution models of different groove inserts are set up. Research shows that: in the same machining conditions, different groove inserts, which with complex grooves and a periodic function grooves have the best machining performance. All above study results will provide a certain theoretic base for improving the workshop environment, controlling and predicting the noise and optimizing the design of insert groove.

Abstract: 2-D pressure model in axial and radial direction was proposed to simulate response of copper subjected to micro laser shock peening (μLSP) according to the size effect in the propagation of shock wave induced by laser in microscale. Simulations under 1-D and 2-D pressure model were conducted respectively in order to explore the effect of pressure in radial direction. The results show that distribution of residual stress and plastic deformation in depth and width are obviously different, and response of copper under 2-D pressure model are more close to the experimental results. The pressure effect in radial direction in the propagation of shock wave shouldnt be ignored, and 2-D shock wave pressure model plays an important role in accurate simulation of μLSP.

Abstract: The lives of the two CERMETS cutters were investigated when turning 45carbon steel in the same cutting condition. The effect of tool orthogonal clearance on tool life was also researched in this paper. The results of the experiment were indicated as: the cutting performance of Nano TiN modified TiC-based CERMETS cutters was obviously superior to that of ultra-fine Ti(C, N)-based CERMETS cutters. And the length of cutting path of the two cutters was longest with the tool orthogonal clearance of 3-4°.

Abstract: Discrete element model of fully sintering dental zirconia was constructed and calibrated. Based on the model, the dynamic process of low-speed milling of zirconia was simulated, and the effects of different cutting speeds, cutting widths and federates on the formation of surface cracks were also analyzed. Results show that residue cracks number and maximum depth increases significantly with increase of the cutting width, while the influence of cutting speed and federates is not distinct. That shows the possibility of high-speed machining on fully sintering dental zirconia with development of coating technology of cutting tool.