Papers by Author: Xing Ai

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Authors: Zhan Qiang Liu, Xing Ai, Zhao Hui Wang
Abstract: This paper presents a comparison study of surface hardening by grinding versus machining. The technological, economical and ecological merits of machining hardening and grind-hardening process for steels are described. The mechanisms of machining hardening and grind-hardening of steels are investigated and compared. The phase transformation, plastic deformation and white layer generation are the principal factors contributing to the hardened surface layer by machining and grinding. The influences of the process parameters on the penetrated hardness are given for both grind-hardening and machining hardening operations. The future development trends of the grind-hardening and machining hardening are also presented.
Authors: Jun Zhao, Xing Ai, Su Yu Wang, Zeng Wen Liu
Abstract: This paper focuses on developing an empirical model for the prediction of milling forces in high-speed end milling of P20 die-mold steel. The spindle speed, feed rate, axial and radial depth of cut are considered as the affecting factors. The data for establishing the model are derived from high-speed end milling experiments conducted on a 5 axis machining center according to the principles of DOE (design of experiments) method. The influences of milling parameters on milling forces are investigated by analyzing the experimental curves. Consequently, multiple-regression analysis is applied in developing the empirical model. Furthermore, the significances of the regression equation and regression coefficients are statistically tested in this paper to validate the model.
Authors: Chuan Zhen Huang, M. Li, Sui Lian Wang, Jing Sun, Han Lian Liu, Xing Ai
Authors: Su Yu Wang, Jun Zhao, Xing Ai
Authors: Qing Hua Song, Xing Ai
Abstract: The efficiency of the high-speed milling process is often limited by the occurrence of chatter. In order to predict the occurrence of chatter, accurate models are necessary. With the speed increasing, gyroscopic effect plays an important pole on the system behavior, including dynamic characteristic and rotating behavior. Considering the influence of gyroscopic effect on rotating behavior, an updated model for the milling process is presented which features as model of the equivalent profile of tool. In combination with this model, a nonlinear instantaneous cutting force model is proposed. The use of this updated equivalent profile of tool results in significant differences in the static uncut thickness compared to the traditional model.
Authors: Song Zhang, Xing Ai, Wei Xiao Tang, J.G. Liu
Abstract: High-speed machining has become mainstream in machining manufacturing industry. In industries such as moldmaking and aerospace, it has become the norm rather the exception. The centrifugal force increases as the square of the speed. At rotational spindle speeds of 6,000 r/min and higher however, centrifugal force from unbalance becomes a damaging factor and it reduces the life of the spindle and the tool, as well as diminishes the quality of the finished product. Under high rotational speed, good balance becomes issue. High-speed machining experimental results shown that a well-balanced tool/toolholder assembly could obviously improve machining quality, extend tool life and shorten downtime for spindle system maintenance etc.
Authors: Rui Zhang, Yi Wan, Xing Ai, Zhan Qiang Liu
Abstract: The oxide film on implant surface of biomedical titanium alloy is crucial to its bioactivity and biocompatibility in human body. A new method is proposed to obtain titanium oxide film by cutting process in oxygen-enriched atmosphere. A gas mixing system is firstly developed to provide oxygen-argon mixed gas to the flank face of insert during turning. The results show that oxygen-enriched atmosphere promote the oxidation reaction of titanium element. Thicker oxide film can be obtained in oxygen-enriched condition than that in natural atmosphere. The corrosion resistance is also improved significantly by this method in electrochemical test.
Authors: Xing Ai, Zhao Qian Li
Authors: Chong Hai Xu, Chuan Zhen Huang, Xing Ai
Abstract: Thermal shock resistance is one of the primary properties for the ceramic cutting tool materials with perspectives in high speed machining. An optimum model for the compositional design of the composite ceramic tool materials is built based on the thermal shock resistance. The thermal stress fracture resistance factor R is used to characterize the thermal shock resistance of the ceramic material. Results show that the developed (W,Ti)C/SiC/Al2O3 multiphase ceramic tool material can be expected to achieve the highest thermal shock resistance when the volume fraction of (W,Ti)C and SiC is about 15.8% and 24.8%, respectively. Thermal fracture resistance of the (W,Ti)C/SiC/Al2O3 ceramic tool material is approximately 81-88% higher than that of the pure alumina ceramic when machining the hardened carbon steel, which coincides well with the theoretical prediction from the optimum model. It suggests that the method used here is feasible for the development of ceramic tool materials with designed thermal shock resistance.
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