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Li X.,Qiqihar University | Li X.,Qiqihar CNC Equipment Corporation Ltd. | Bao L.,Qiqihar University | Wang S.,Qiqihar University | And 7 more authors.
Advanced Materials Research | Year: 2012

The rapid growth of modern technology place greater demand on electronic products' performance and quality. As for the printed circuit board (PCB) assembly of electronic components through surface mounting technology (SMT), high-pixel charge coupled device (CCD) can only screen local images during image collection because of its limited vision. A rapid image mosaic technology has been proposed to seamlessly stitch the local images with overlapping boundaries. The complete image of PCB assembly has been acquired through rapid area matching method within double Mark points and Mark circle. The experiment results show that this method can greatly reduce the image-mosaic time and fairly improve the real-time performance of modern automatic optical inspection (AOI) equipment. Furthermore, such method avoids the alignment error from the characteristic points for noise jamming or noise shielding, and therefore obtains better robustness. © (2012) Trans Tech Publications, Switzerland. Source


Li X.,Qiqihar University | Li X.,Qiqihar CNC Equipment Corporation Ltd. | Li X.,Harbin University of Science and Technology | Du X.,Qiqihar University | And 3 more authors.
Applied Mechanics and Materials | Year: 2012

With increasing demands for product quality, and the performance of assembly equipment plays a decisive role for product quality, national experts and scholars conduct in-depth research on the performance of the assembly equipment. In this paper, a research simulation on hydrostatic bearing performance of heavy-duty vertical lathes DVT(digital vertical tool) 500 is carried out by using finite element software FLUENT to simulate the fluid pressure field and temperature field distribution of sector oil recess at different work platform rotational speed. The law of these field distributions is also obtained. The results show that: the rotational speed of the work platform has a greater impact on pressure field and temperature field of gap fluid flow. Numerical results can reflect the true hydrostatic bearing fluid movement, the actual simulation results provide a theoretical basis for optimization design of the Engineering hydrostatic bearing oil cavity. © (2012) Trans Tech Publications, Switzerland. Source


Zhang Y.,Harbin University of Science and Technology | Yu Z.,Harbin University of Science and Technology | Chen Y.,Harbin University of Science and Technology | Shao J.,Harbin University of Science and Technology | And 2 more authors.
High Technology Letters | Year: 2014

In order to improve the cutting stiffness, the paper studies the vertical hydrostatic bearing in the slide when a ram is in feed process. The change of the oil film thickness on hydrostatic guide rail and the curve of the oil film thickness in various cutting forces are calculated and a relation model through theoretical analysis method is derived. The pressure field of the guide rail recess is simulated based on the finite volume method and demonstrated through experiments. The study is of vital theoretical significance for the improvement of machining accuracy of numerical control machines and the entire computer numerical control (CNC) equipment and provides valuable theoretical basis for the design of hydrostatic guide rail in engineering practice. Copyright © by HIGH TECHNOLOGY LETTERS PRESS Source


Yu X.-D.,Harbin University of Science and Technology | Sun D.-D.,Harbin University of Science and Technology | Meng X.-L.,Heilongjiang Polytechnic | Wu X.-G.,Harbin University of Science and Technology | And 3 more authors.
Journal of Computational and Theoretical Nanoscience | Year: 2015

The oil film thickness of a hydrostatic bearing is an important indicator of lubrication characteristics of a multi-pad hydrostatic thrust bearing, lubrication characteristics of hydrostatic thrust bearing are affected significantly by the rotational speed of the worktable, especially under the condition of high speed and heavy loading, and its effect is more significant. A multi-pad hydrostatic thrust bearing with circular recess is taken as research objects, the relation between oil film thickness and rational speed of the worktable is deduced by using lubricating theory and tribology principle. A test rig is designed for testing the oil film thickness of the above bearing, and a proving experiment is carried out. The calculated results qualitatively agree well with the experimental data, it has been found that by increasing the rotational speed the volume flow rate of efflux from the oil recess and the shear heat of the oil recess are increased, and lubricating oil viscosity decline sharply, oil film grow thin quickly, together with bearing friction pair uneven deformation, local bearing friction pair appear boundary lubrication or dry friction, and then happen tribology failure. The study provides the basic data for the hydrostatic thrust bearing design and lubrication, and implements of the prediction of the hydrostatic thrust bearing lubrication characteristics, and reaches the purpose of reducing economic loss. Copyright © 2015 American Scientific Publishers. Source


Yu X.-D.,Harbin University of Science and Technology | Fu X.,Harbin University of Science and Technology | Meng X.-L.,Heilongjiang Polytechnic | Liu D.,Harbin University of Science and Technology | And 2 more authors.
Journal of Computational and Theoretical Nanoscience | Year: 2015

The simulation concerning temperature performance of hydrostatic thrust bearing with circular recesses is carried out considering the changes in viscosity in order to solve the thermal deformation of the hydrostatic thrust bearing in the heavy computer numerical control (CNC) equipment. The three-dimensional temperature field of gap fluid between the rotary worktable and the base is computed based on a three-dimensional TEHD model. The influence of the rotational speed and viscosity on the bearing temperature performance is studied based on computational fluid dynamics (CFD) and lubrication theory, and the method reveals the temperature distribution law. A test rig is designed for testing the temperature of hydrostatic thrust bearing with circular recess. Good agreement has been obtained between predicted theoretical performance and that experimentally measured. The results demonstrate that rotational speed, oil viscosity, bearing recess size and location have a great influence on the temperature performance of hydrostatic thrust bearing. This study is expected to serve as a theoretical basis for design and development of the heavy computer numerical control equipment. Copyright © 2015 American Scientific Publishers All rights reserved. Source

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