Papers by Author: Lai Xi Zhang

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Authors: Lai Xi Zhang, Xing Song Wang
Abstract: A new four-point algorithm for orientation and position regulation of an end-effector for a flexible drilling robot is presented in this paper.Four non-coplanar points in three-dimensional space can determine a unique sphere tangent to them, we can find out this sphere’s center point and radii and regard the shape of a workpiece surface in machining area approximately as such a sphere. A vector from the machining point to the center point is regarded as the one normal to the workpiece surface. By this principle, the algorithm firstly measured and calculated a vector normal to drilling machining area on curved surface by four points,and then calculated the difference between this normal vector and the axis of the spindle. If there is difference, the algorithm further figures out the angles of two revolving axes on end-effector and the displacements of three linear axes on robot main body, which should be adjusted.Simulation results of two kinds of curved surface show that the accuracy and efficiency satisfy the practical requirements using this algorithm.
Authors: Xiao Long Shen, Yong Xin Luo, Lai Xi Zhang, Hua Long
Abstract: After adopting the constitutive equations of the nonlocal elastic media in the form of Eringen, and making use of the Laplace transformation, the vibration governing equation of nonlocal elastic beam in the Kelvin media are established. Unlike classical elastic models, the stress of a point in a nonlocal model is obtained as a weighted average of the field over the spatial domain, determined by a kernel function based on distance measures. The motion equation of nonlocal elastic beam is an integral differential equation, rather than the differential equation obtained with a classical local model. Solutions for natural frequencies and modes are obtained. Numerical examples demonstrate the efficiency of the proposed method for the beam with simple boundary conditions.
Authors: Yong Xin Luo, Xiao Long Shen, Hua Long, Lai Xi Zhang
Abstract: In a larger-power CNC milling machine, the milling stability of CNC small size tool which is less than φ 25 diameters is restricted under a certain degree. Authors studied CNC milling chatter stability by the experiment and simulation; they had researched those influences of tool’s diameter, suspended length and craft of manufacturing system on chatter stability domain. Researches show that the larger diameter and shorter suspended length of the tool can improve the stability of milling, and also can improve critical axial cutting depth. The lobes of chatter stability domain can forecast effectively critical axial cutting depth and relevant to milling speed, can better mining machine cutting potential.
Authors: Lai Xi Zhang, Xing Song Wang, Shu Lin Liu
Abstract: A new 2-DOFs dynamic turning model including the compliance of workpiece and cutting tool is developed. In past studies, most of them were based on SDOF models and either the workpiece or tool was simplified as rigid one. Meanwhile, traditional regenerative chatter models focus mainly on cross cutting which was particularly prone to chatter. It is evident that such models cannot descript cutting system comprehensively. In order to tackle this problem, we introduce the overlap factor making the new model also suitable for length-wise cutting. Stability was analyzed after performing the Laplace transformation, correlation between critical chip width and spindle speed was derived. Simulation suggests that the new model has a larger critical chip width which complies with practical situation.
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