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Jin Kyung Choi - One of the best experts on this subject based on the ideXlab platform.

  • thermal characteristics of the spindle Bearing System with a gear located on the Bearing span
    International Journal of Machine Tools & Manufacture, 1998
    Co-Authors: Jin Kyung Choi
    Abstract:

    High cutting speeds and feeds are essential requirements of a machine tool structure to accomplish its basic function which is to produce a workpiece of the required geometric form with an acceptable surface finish at as high a rate of production as is economically possible. Since Bearings in high speed spindle units are the main heat source of total cutting System, in this work, the thermal characteristics of the spindle Bearing System with a tilting axis were investigated using finite element method to improve the performance of the spindle Bearing System. Based on the numerical results, a specially designed prototype spindle Bearing System was manufactured. Using the manufactured spindle Bearing System, the thermal characteristics were measured and compared to the numerical results. From the comparison of the numerical results with the experimental results, it was found that the finite element method predicted well the thermal characteristics of the spindle Bearing System.

  • Characteristics of a spindle Bearing System with a gear located on the Bearing span
    International Journal of Machine Tools and Manufacture, 1997
    Co-Authors: Jin Kyung Choi, Dai Gil Lee
    Abstract:

    The spindle Bearing System is the main source of the total cutting point compliance of machine tool structures. In this work, the static and dynamic characteristics of a spindle Bearing System driven by a gear located on the Bearing span were investigated using the analytical and finite element methods. Based on the calculated results, a prototype spindle Bearing System was manufactured and its static and dynamic characteristics were measured. From the comparison of the experimental results with the calculated results, it was found that the finite element method predicted well the static and dynamic characteristics of the spindle Bearing System.

Bo-chang Shen - One of the best experts on this subject based on the ideXlab platform.

Hong-yuan Jiang - One of the best experts on this subject based on the ideXlab platform.

Hsiao-wei D. Chiang - One of the best experts on this subject based on the ideXlab platform.

  • Turbomolecular pump rotor-Bearing System analysis and testing
    Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2009
    Co-Authors: Hsiao-wei D. Chiang, Chih-pin Kuan
    Abstract:

    During turbomolecular pump design, it is very critical to know the dynamic behavior of the rotor-Bearing System, which is also of great importance to the pump performance. In this study, a typical small size turbomolecular pump was used. Using an inertial coordinate System, the dynamic models of the pump rotor-Bearing Systems included gyroscopic moments, rotary inertias, and bending and shear deformations. The models were analyzed in order to predict the natural frequencies, to produce critical speed maps, and to estimate the Bearing stiffness. These rotor-Bearing System analyses were then applied to the turbomolecular pump rotor System applications. Both theoretical and experimental analyses were used to study the rotor-Bearing System. Modal testing and dynamic test were used to verify the analytical results, including the critical speed map and the Bearing stiffness. Very good agreement was demonstrated between the analysis and the test data. The analysis demonstrated that the rotor operation of 51600rp...

  • A Microturbine Rotor-Bearing System Analysis
    Volume 4: Turbo Expo 2002 Parts A and B, 2002
    Co-Authors: Hsiao-wei D. Chiang, Wes Jeng, Shun-hsu Tu, Wei-chen Li
    Abstract:

    A microturbine of 12-pound thrust was developed for the Unmanned Aerial Vehicle (UAV) applications. Recent tests of the microturbines reveal problems associated with rear ball Bearing integrity after extended run times. The microturbine rotor design originally calls for a critical speed margin of at least 15∼20% to prevent excessive vibrations. However, the microturbine was using an existing turbocharger rotor component with unknown margins. Therefore, the purpose of this paper is to perform both theoretical and experimental analyses of the dynamic characteristics of the 12-pound thrust microturbine rotor-Bearing System. This rotor-Bearing System analyses will start with a finite element (FEM) rotor-Bearing System dynamic model, then using modal testing and dynamic engine test to verify the analysis results including critical speed map and Bearing stiffness. In this paper, the rotor-Bearing System dynamic model will be established under an inertia coordinate System. Through finite element method, this model can be used to predict natural frequencies, critical speed map, and Bearing stiffness. Also, under free-free condition, a modal testing will be performed, and its results are used to compare with the FEM model. Then the gyroscopic moment effects are included in the FEM model to calculate the critical speed map. Finally the critical speed map is used to compare with the results of the dynamic experiments of the 12-pound thrust microturbine engine and the Bearing stiffness is estimated through an optimization approach. Examination of the microturbine engine and recent product developments indicate that thrust performance and engine life goals can be improved to upgrade the present design. With the rotor-Bearing System analysis, the goal of increasing the current engine life and improved performance is sought as a practical goal for the microturbine design.Copyright © 2002 by ASME

  • Turbomachinery Dual Rotor-Bearing System Analysis
    Volume 4: Turbo Expo 2002 Parts A and B, 2002
    Co-Authors: Hsiao-wei D. Chiang, Chih-neng Hsu, Wess Jeng
    Abstract:

    It is very common for aircraft engines to have dual rotor or even triple rotor designs. Due to the complexity of having multiple rotor design, the transfer matrix methods have used in the past to deal with multiple rotor-Bearing Systems. However, due to transfer matrix method’s assumptions, sometimes resulted in numerical stability problems or root-missing problems. The purpose of this paper is to develop a Systematic theoretical analysis of the dynamic characteristics of turbomachinery dual rotor-Bearing Systems. This dual rotor-Bearing System analysis will start with a finite element (FEM) rotor-Bearing System dynamic model, then using different methods to verify the analysis results including critical speed map and Bearing stiffness. In an inertia coordinate System, a general model of continuous dual rotor-Bearing Systems is established based on a lagrangian formulation. Gyroscopic moment, rotary inertia, bending and shear deformations have been included in the model. From a point of view of the Systematic approach, a solution of the finite element method is used to calculate the critical speeds by several different methods, which in turn can help to verify this dual rotor-Bearing System approach. The effects of the speed ratio of dual rotors on the critical speed will be studied, which in turn can be used as one of the dual rotor design parameters. Also, both critical speeds are in effect functions of dual rotor speeds. Finally, the Bearing stiffness between high speed and low speed shafts not only affect the critical speeds of the dual rotor System, but also affect the mode shapes of the System. Therefore, the Bearing stiffness in between is of even greater importance in turbomachinery dual rotor or multiple rotor design.Copyright © 2002 by ASME

Sheng-bo Li - One of the best experts on this subject based on the ideXlab platform.