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Zhang L.,Tianjin University | Gao W.,Tianjin University | Zhang D.,Tianjin University | Chang W.,Tianjin University | And 2 more authors.
Advances in Mechanical Engineering | Year: 2016

The milling stability is one of the important evaluation criterions of dynamic characteristics of machine tools, and it is of great importance for machine tools' design and manufacturing. The milling stability of machine tools generally varies with the position combinations of moving parts. The traditional milling stability analysis of machine tools is based on some specific positions in the whole workspace of machine tools, and the results are not comprehensive. Furthermore, it is very time-consuming for operation and calculation to complete analysis of multiple positions. A new method to rapidly evaluate the stability of machine tools with position dependence is developed in this article. In this method, the key position combinations of moving parts are set as the samples of calculation to calculate the dynamic characteristics of machine tools with SAMCEF finite element simulation analysis software. Then the minimum critical axial cutting depth of each sample is obtained. The relationship between the position and the value of minimum critical axial cutting depth at any position in the whole workspace can be obtained through established response surface model. The precision of the response surface model is evaluated and the model could be used to rapidly evaluate the milling stability of machine tools with position dependence. With a precision horizontal machining center with box-in-box structure as an example, the value of minimum critical axial cutting depth at any position is shown. This method of rapid evaluation of machine tools with position-dependent stability avoids complicated theoretical calculation, so it can be easily adopted by engineers and technicians in the phase of design process of machine tools. © SAGE Publications Ltd, unless otherwise noted. Manuscript content on this site is licensed under Creative Commons Licenses. Source


Guan J.-L.,Beijing University of Technology | Ma X.-Q.,Beijing University of Technology | Cao C.-G.,Beijing Precision Machinery and Engineering Research Co. | Zhang X.-H.,Beijing University of Technology
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2015

Aimed at the problem of large diameter Fresnel lens mold machining, this paper analyzed the large diameter Fresnel lens mold machining mechanism based on the ABAQUS finite element simulation software and modal test methods. The design and mold machining principle of Fresnel lens were introduced. Combined with the material constitutive relation and material failure criteria, a two-dimensional orthogonal cutting model was established and the chip derived from the simulation was compared with the chip from modal test, with a consequent verification of the feasibility of simulation chip model. The simulation contributes to an investigation into the effects of the cutting speed and feed on chip formation process. Results show that the material strength and plastic brittle have significant impact on chip morphology in the H62 brass mold processing, the material strength is improved with the increase of strain rate, and the evolution process of the chip can be divided into: ribbon cuttings, serrated chips, and cell chips. ©, 2015, Beijing University of Technology. All right reserved. Source


Wang M.,Beijing University of Technology | Zhang X.-Y.,Beijing University of Technology | Zan T.,Beijing University of Technology | Zhang J.-X.,Beijing University of Technology | And 3 more authors.
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2012

To investigate the static and dynamic performance of high-speed electric spindle, the finite element analysis method based on ANSYS was applied to determine static stiffness, natural frequencies and modal shapes of the spindle. By comparative analysis between the finite analysis and the modal experimental results, the error of the spindle's natural frequencies is very small and the modal shapes are basically identical. That shows that the boundary conditions and parameters' set are reasonable, and the results have practical value. By employing this finite element modal, the influence of the spindle span on the dynamics of the spindle was studied and the optimal range of the spindle span was determined. Results show that combining finite element analysis with modal experiment, the dynamic performance can be analyzed effectively and the structure optimization can be realized. Source


Guan J.-L.,Beijing University of Technology | Ma X.-Q.,Beijing University of Technology | Cao C.-G.,Beijing Precision Machinery and Engineering Research Co. | Zhang X.-H.,Beijing University of Technology | Zhu L.,Beijing University of Technology
Advanced Materials Research | Year: 2014

This paper analyzed the large diameter Fresnel lens mold machining mechanism based on modal test methods.The design and mold machining principle of Fresnel lens were introduced. Explored the cutting speed and feed on chip formation process. The results show that: the material strength and plastic brittle have significant impact on chip morphology in the H62 brass mold processing, an improvement of material strength with the increase of strain rate and the evolution process of the chip can be divided into: ribbon cuttings, serrated chips, cell chips. © (2014) Trans Tech Publications, Switzerland. Source


Liu T.,Tianjin University | Gao W.,Tianjin University | Gao W.,University of Warwick | Tian Y.,Tianjin University | And 7 more authors.
Applied Thermal Engineering | Year: 2015

Traditional bath recirculation cooler for precision machine tools always has the uniform and open-loop cooling strategy onto different heat generating parts. This causes redundant generated heat being transferred into the machine structure, and results in unsatisfactory thermal errors of precision machine tools. For the solution of this problem, this paper presents the differentiated multi-loops bath recirculation system. The developed system can accomplish differentiated and close-loop cooling strategies onto machine heat generating parts during its operation. Specially, in order to illustrate the advantages of this system, constant supply cooling powers strategy is presented with its applications onto a certain type of built-in motorized spindle. Consequently, advantages of the proposed strategy based on the differentiated multi-loops bath recirculation system are verified experimentally in the environment within consistent temperature (TR = 20 ± 0.3°C). Compared with room temperature tracing strategy based on the traditional bath recirculation cooler, the constant supply cooling powers strategy is verified to be advantageous in spindle temperature stabilization and thermal errors decrease. © 2014 Elsevier Ltd. All rights reserved. Source

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