Papers by Author: Y.F. Li

Abstract: A cutting chatter forecast method based on continuous wavelet feature and multi-class spherical Support Vector Machines is studied in this paper. The method based on continuous wavelet transform extracts the cutting vibration signal feature and uses multi-class spherical Support Vector Machines to discern the chatter. In order to simplify computational complexity when binary classification SVM turn to multi-class classification, the algorithm makes every kind of samples have a spherical SVM. In the feature space identified the test sample and spherical SVM centre distance as a decision-making function. Experiments show that using combine spherical SVM with continuous wavelet feature Vector has good recognition effect in the milling chatter recognition system. Chatter inoculation forecast accuracy reaches 95%, and chatter outbreak forecast accuracy reaches 97.5%.

Abstract: A model is established with considering the vibration effect of microstructure on milling surface formation, the impact of vibration on surface profile formation is also studied, which is simulated by the approach of vibration displacement in actual measurement. The on line monitoring of cutting vibration can be realized efficiently by the above method, and it is a coincident microstructure of milling surface between simulation and actual processing. In the result, it is cutting vibration that plays an main role in microstructure of milling surface formation with the known cutting parameters.

Abstract: During precise hard cutting, back cutting depth and feed rate are relatively small. Study on the influence of PCBN (Polycrystalline Cubic Boron Nitride) cutting tools edge (chamfer edge or cutting edge radius) on cutting force is important. As the effect of cutting edge on mechanism of shear slip plane is very complicated, so to study the effect of consider cutting edge parameters and cutting parameters by genetic algorithm on cutting force, to build up cutting force model of precise hard cutting. It is feasible to predict cutting force by genetic algorithm with experiment.

Abstract: Microcosmic and macroscopic form of CFRP holes drilled by new PCD tool were observed in this paper. Location and distribution of burr and fiber direction of burr were analyzed, and formation mechanism of burr of CFRP hole exit is studied tentatively. The methods of inhibit the formation of burr formation were put forward from the design principles of the tool geometry parameters.

Abstract: In this paper, modal analysis of ball end mills is modeled by finite element to work out natural frequency and chatter model in tooling system and to calculate the limit curve of stability in single degree freedom system. The effect of cutter flute length and cutter tooth number on limit curve of stability in single degree freedom system is also discussed. The research results show that steady critical cutting depth of milling system declines while the cutter flute length increases, but the trend is not linear, which shows increase partly. An engineering optimization design is made on milling cutter geometrical parameters based on this conclusion.

Abstract: Polycrystalline diamond (PCD) composite sheet is a kind of material for cutter blank, which is formed by uniformly mixing micron diamond particles and metal binder powder such as Co and Ni, then sintered on WC under high pressure and high temperature. PCD tools have broad application and very high commercial value. However, compared with other materials, PCD tools’ service life relies greatly on blade sharpening quality. This paper just experimented on preparing precision blade of CTB002 PCD composite sheet on grinding machine of high precision diamond tools and with different performance parameters of TYROLIT diamond grinding wheel. Rotational speed of grinding wheel, grain size of grinding wheel and grinding pressure were researched in the orthogonal test method, which have the largest influence on grinding process, and influencing rules and the best combination of the three parameters are obtained.

Abstract: There is a bright future for hard cutting technique because of good machining flexibility, high efficiency, no pollution. This paper presents effect rules of cutting parameters (cutting speed, feed, depth of cutting) on integrality of machined surface (surface roughness, surface hardness, surface hardened depth, residual stresses, surface texture) based on orthogonalization test. Optimal cutting parameters are selected according to these rules. Surface roughness (Ra) is up to 0.6µm in terms of selected optimal cutting parameters.