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Cao H.,Xian Jiaotong University | Cao H.,Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment | Li B.,Xian Jiaotong University | He Z.,Xian Jiaotong University
Advanced Materials Research | Year: 2012

Based on a cutting dynamics model, a new digital machining process model that integrates workpiece quality and machining condition information is proposed, and the mapping relationship between machine tool structural dynamics and product quality information (e.g., dimension error, surface shape) is analyzed in detail. On the basis of the digital machining process model, the condition monitoring and fault diagnosis method of the machining process is investigated, and an implementation flowchart of the method is proposed with explanations of critical techniques. Finally, the proposed model is applied to the condition monitoring and fault diagnosis of the machining process of a CNC end milling machine. The damage of its spindle bearing is detected successfully, which provides the proof for the root cause identification of machining error in the digital machining process.


Shi B.,Beijing Institute of Technology | Wang X.,Beijing Institute of Technology | He K.,Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment
2010 IEEE International Conference on Automation and Logistics, ICAL 2010 | Year: 2010

A vibration signal analysis system introduced by this paper adopts hybrid programming of Matlab and Delphi, using data file for agency to achieve data communication.The procedure of signal analysis system is written and turned into the independent executable file under the environment of Matlab, which is called under the environment of Delphi. The system combined programming languages of matlab and delphi with comprehensive utilization of powerful numerical calculation processing function of matlab and system exploitation capability of Delphi, which shortens the period of developing system software greatly , saves development costs of exploitation and fully embodies the advantages of the system. © 2010 IEEE.


Cao H.,Xian Jiaotong University | Cao H.,Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment | Li B.,Xian Jiaotong University | He Z.,Xian Jiaotong University
International Journal of Machine Tools and Manufacture | Year: 2012

The chatter stability of machine tool is dependent on the dynamic behavior of the spindle system, which is often expressed as the frequency response function (FRF) at the tool tip. The stability lobe diagram generated from stationary FRFs can lead to an inaccurate prediction in high and ultra high speed machining. This paper presents an alternative approach to predict the chatter stability lobes of high-speed milling with consideration of speed-varying spindle dynamics. With a dynamic model of a high-speed spindle system, the speed effects (i.e., gyroscopic moment and centrifugal forces) on both the spindle shaft and bearings are investigated systematically with simulations and experiments. The gyroscopic moment of the spindle shaft can increase the cross FRFs, but can hardly affect the direct FRFs at the tool tip due to the damping of the spindle system. The centrifugal forces on both the shaft and bearings lower the overall spindle system stiffness evidently as the speed increases. The speed-dependent FRFs at the tool tip are obtained from the dynamic spindle model and then integrated into the characteristic equation of the dynamic milling system. Nyquist stability criterion is used to generate the chatter stability lobe of high-speed milling operations. It is shown that the stability lobes with speed effects shift to the low speed range significantly. Finally, milling tests are performed to validate predicted the speed-dependent stability lobe. © 2011 Elsevier Ltd. Allrightsreserved.


Tang G.,Hunan University of Science and Technology | Chen A.-H.,Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment | Guo Y.-J.,Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2011

The nonlinear dynamic equation of a beam with unique cross-section under pure bending vibration was developed. According to theory of nonlinear dynamics, the singular point and stability of the system was studied. Using theory of chaos, the parametric condition of the beam for chaos occurence under pure bending vibration was explored. According to the parametric condition, the parametric condition of a simply supported beam with unique cross-section for chaos occurence under pure bending vibration was studied the parameter boundary for chaos occurence were obtained.


Zhou L.,Hunan Institute of Engineering | Zhou L.,Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment | Li Y.,Xiangtan University | Fu C.,Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment
Advanced Materials Research | Year: 2011

A finite element method is used to simulate the deep drawing processes of nickel coating with steel substrate into battery shells. The Belytschko-Wong-Chiang shell elements are used and the kinematical work hardening model is adopted, while the ties with failure contact criterion is given to the coating and substrate interface. The stress-strain field and interfacial stresses in the drawing processes are obtained. The nickel coating appeared to be yielded in the drawing processes, of which the maximum effective stress reached 241MPa, and the biggest effective strain reached 0.7524. The interfacial stresses in the coating and substrate varied during the drawing process, and their maximal values reached 40MPa in compressive state. © (2011) Trans Tech Publications, Switzerland.

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