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Yohichi Nakao - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic characteristics of spindle with water-lubricated hydrostatic bearings for ultra-Precision Machine tools
    Precision Engineering, 2020
    Co-Authors: Dmytro Fedorynenko, Rei Kirigaya, Yohichi Nakao
    Abstract:

    Abstract A key component of ultra-Precision Machine tools is the spindle. The motivation for this study was to improve machining accuracies in Precision cutting and grinding by pursuing improvements in the spindle characteristics by designing a sophisticated spindle with water-lubricated hydrostatic bearings. The static bearing stiffness of the developed spindle was investigated in previous studies. In addition to the static bearing stiffness, the dynamic characteristics regarding bearing stiffness also affect significantly on the machining results. In this study, dynamic characteristics of the developed spindle with water-lubricated hydrostatic bearings were investigated via simulations and experiments. Not only bearing dynamics but also rotor dynamics were considered in this study. In the simulation studies, the spindle dynamic characteristics were analysed based on the transfer matrix method. A spindle rotor supported with hydrostatic bearings was represented by discrete sections of the rotor. The mathematical model of transverse linear vibrations of the spindle rotor was derived with distributed parameters for these discretized rotor sections. As a result of the analysis on the amplitude-frequency characteristic, radial displacements of the rotor due to bearing displacement and bending deformation were defined. Then, the frequency characteristics were represented with Nyquist plots. Resonant frequencies and amplitudes formation in the transverse vibration of the rotor were determined. The influence of rotor bending deformations on spindle compliance was assessed. Furthermore, the study examined the influences of the supply pressure of the lubricating fluid, radial clearance and journal diameter of the hydrostatic bearings on the amplitude of the rotor vibration, and the resonance frequency of the system. Furthermore, the dynamic characteristics of the spindle were examined experimentally. The simulation results were in good agreement with the actual spindle dynamics obtained experimentally. The influence of the structural parameters of the rotor and the operating parameters of the bearings on the spindle dynamic characteristics was also determined. It was verified that the amplitude of the vibration of the rotor overhang part was dominantly affected not by bearing stiffness but by bending stiffness of the bearing journal of the front bearing and the length of the rotor overhang. Then it was verified that the resultant displacement of the rotor in the radial direction due to the influence of the bearing characteristics and the structural effect of the rotor is significantly small. Practical recommendations to improve the spindle design in terms of the dynamic characteristics of the spindle with water-lubricated hydrostatic bearings were also derived.

  • Ultra-Precision Machine Tool, Bearing Stiffness
    2015
    Co-Authors: Yohichi Nakao, Fumiyuki Kobayashi, Yuji Sagesaka
    Abstract:

    Spindles used for recent diamond turning Machines are typically supported by hydrostatic bearings. Especially, air hydrostatic bearings are the most common because of low viscosity of air. Low viscosity of lubricant fluid is an important requirement for operating the spindle in a range of higher rotational speeds. However, from a stiffness viewpoint of the bearings, higher compressibilit

  • Design of Spindle Supported by High Stiffness Water Hydrostatic Thrust Bearing
    Volume 12: Systems and Design, 2013
    Co-Authors: Yohichi Nakao, Kohei Yamada, Kenji Suzuki
    Abstract:

    A Precision spindle is a key component of the ultra-Precision Machine tools that are used for machining Precision molds for producing various lenses and other precise parts. The machining accuracy required for the parts now reaches several tens of nanometers. In order to achieve the desired machining accuracy, the precise spindle system with high stiffness bearings is inevitably needed for the ultra-Precision Machine tools. The paper thus deals with a design of a spindle supported by water hydrostatic bearings. An objective of the study is to design the Precision spindle supported by the water hydrostatic bearings with the bearing stiffness of 1 kN/μm. Thus the paper presents the design procedure of the hydrostatic thrust bearings. In particular, the design of the bearing restrictors is introduced. The characteristics of water hydrostatic thrust bearings of the designed spindle are investigated theoretically. The influences of the gap sizes and the supply water pressure on the bearing stiffness are given. It is indicated that the bearing stiffness of 1 kN/μm can be obtained by the spindle design. Structure and materials of the developed spindle are also introduced.Copyright © 2013 by ASME

Chun Hong Park - One of the best experts on this subject based on the ideXlab platform.

  • Modelling vibration transmission in the mechanical and control system of a Precision Machine
    Cirp Annals-manufacturing Technology, 2014
    Co-Authors: Chang-ju Kim, Chun Hong Park
    Abstract:

    Abstract The relative vibration between tool and workpiece factors significantly to the performance of a Precision Machine. This paper develops a model for predicting the vibration transmission from two major excitation sources, ground vibration and fluid bearing force, to the tool and the workpiece position through the mechanical and control system of a Precision Machine. We synthesised the frequency response functions obtained from a finite element analysis of the Machine to create transmissibility matrices that define the dynamic behaviours of the electromechanical system. The validity of the developed model was checked by comparing the measured relative vibrations to the results calculated from the measured excitations.

  • development of an ultra Precision Machine tool for micromachining on large surfaces
    International Journal of Precision Engineering and Manufacturing, 2009
    Co-Authors: Chun Hong Park, Chang Kyu Song, Jooho Hwang, Byungsub Kim
    Abstract:

    The goal of this research is to develop a multi-functional ultra Precision Machine to generate micro features on large surfaces. Design and characteristic analyses of our Machine are presented. The analyses include its structural analysis and accuracy tests. Each axis of the developed Machine was corrected and/or compensated from accuracy tests enough to generate grooves on workpieces with a less than 10 µm pitch size. After compensation, the 2-dimension position error between X-axis and Y-axis was reduced to 1.4 µm for a 400×400 mm2 surface. From a 24 hours relative thermal displacement test between Y-axis and Z-axis, the Machine showed a stable thermal displacement which was measured to be less than 1 µm. From groove machining tests, our Machine could successfully generate 5 µm and 10 µm pitch grooves and showed a stable micro machining characteristics. From this research, we can conclude that the developed Machine has mechanical characteristics enough to generate less than 10 µm pitch grooves on a 400×400 mm2 surface.

  • development of an ultra Precision hydrostatic guideway driven by a coreless linear motor
    International Journal of Precision Engineering and Manufacturing, 2005
    Co-Authors: Chun Hong Park, Jooho Hwang, Deug Woo Lee
    Abstract:

    In order to develop the hydrostatic guideways driven by a coreless linear motor for ultra Precision Machine tools, a prototype of guideway is designed and tested. A coreless linear DC motor with a continuous force of 156 N and a laser scale with a resolution of 0.01 ㎛ are used in the system. Experimental analysis on the static stiffness, motion errors, positioning error and its repeatability, micro step response and velocity variation of the guideway are performed. The guideway shows infinite stiffness within 50 N applied load in the feed direction, and by the motion error compensation method using the Active Controlled Capillary, 0.08 ㎛ linear motion error and 0.1 arcsec angular motion error are acquired. The guideway also reveals 0.21 ㎛ positioning error and 0.09 ㎛ repeatability, and it shows stable responses following a 0.01 ㎛ resolution step command. The velocity variation of feeding system is less than 0.6%. From these results, it is estimated that the hydrostatic guideway driven by a core less linear motor is very useful for the ultra Precision Machine tools.

  • A review on research in ultra Precision engineering at KIMM
    International Journal of Machine Tools & Manufacture, 1999
    Co-Authors: Chun Hong Park
    Abstract:

    A brief review of current research work in the field of ultra Precision engineering at Korea Institute of Machinery and Materials (KIMM) is presented in this paper. Some case studies covering the system integration of ultra Precision Machine tools and core technology of Machine tool elements such as air bearing, hydrostatic guide and friction drive are introduced, and some progress in ultra Precision machining processes are also introduced. The examples are chosen to show the present demands and status of Korean industries in the field of Precision and ultra Precision technology.

D J Gordon - One of the best experts on this subject based on the ideXlab platform.

  • Precision Machine tool X–Y stage utilizing a planar air bearing arrangement
    Cirp Annals-manufacturing Technology, 2010
    Co-Authors: Kaan Erkorkmaz, J. M. Gorniak, D J Gordon
    Abstract:

    Abstract This paper presents a new X–Y stage concept for Precision Machine tools. A large work area (300 mm × 300 mm) is achieved using a T-type gantry arrangement, which locates the work table supported on a vacuum preloaded air bearing on top of a reference granite surface. Actuation is provided with direct drives that fulfil the functions of motion controls, stiffness enhancement, and vibration damping. Thermal deformations are mitigated by designing internally cooled motor couplings. The error budget for the stage, as well as multivariable control law design and stability analysis, and metrology results are discussed in the paper.

  • Precision Machine tool X-Y stage utilizing a planar air bearing arrangement
    CIRP Annals - Manufacturing Technology, 2010
    Co-Authors: Kaan Erkorkmaz, J. M. Gorniak, D J Gordon
    Abstract:

    This paper presents a new X-Y stage concept for Precision Machine tools. A large work area (300 mm ?? 300 mm) is achieved using a T-type gantry arrangement, which locates the work table supported on a vacuum preloaded air bearing on top of a reference granite surface. Actuation is provided with direct drives that fulfil the functions of motion controls, stiffness enhancement, and vibration damping. Thermal deformations are mitigated by designing internally cooled motor couplings. The error budget for the stage, as well as multivariable control law design and stability analysis, and metrology results are discussed in the paper. ?? 2010 CIRP.

Kaan Erkorkmaz - One of the best experts on this subject based on the ideXlab platform.

  • Precision Machine tool X–Y stage utilizing a planar air bearing arrangement
    Cirp Annals-manufacturing Technology, 2010
    Co-Authors: Kaan Erkorkmaz, J. M. Gorniak, D J Gordon
    Abstract:

    Abstract This paper presents a new X–Y stage concept for Precision Machine tools. A large work area (300 mm × 300 mm) is achieved using a T-type gantry arrangement, which locates the work table supported on a vacuum preloaded air bearing on top of a reference granite surface. Actuation is provided with direct drives that fulfil the functions of motion controls, stiffness enhancement, and vibration damping. Thermal deformations are mitigated by designing internally cooled motor couplings. The error budget for the stage, as well as multivariable control law design and stability analysis, and metrology results are discussed in the paper.

  • Precision Machine tool X-Y stage utilizing a planar air bearing arrangement
    CIRP Annals - Manufacturing Technology, 2010
    Co-Authors: Kaan Erkorkmaz, J. M. Gorniak, D J Gordon
    Abstract:

    This paper presents a new X-Y stage concept for Precision Machine tools. A large work area (300 mm ?? 300 mm) is achieved using a T-type gantry arrangement, which locates the work table supported on a vacuum preloaded air bearing on top of a reference granite surface. Actuation is provided with direct drives that fulfil the functions of motion controls, stiffness enhancement, and vibration damping. Thermal deformations are mitigated by designing internally cooled motor couplings. The error budget for the stage, as well as multivariable control law design and stability analysis, and metrology results are discussed in the paper. ?? 2010 CIRP.

J. M. Gorniak - One of the best experts on this subject based on the ideXlab platform.

  • Precision Machine tool X–Y stage utilizing a planar air bearing arrangement
    Cirp Annals-manufacturing Technology, 2010
    Co-Authors: Kaan Erkorkmaz, J. M. Gorniak, D J Gordon
    Abstract:

    Abstract This paper presents a new X–Y stage concept for Precision Machine tools. A large work area (300 mm × 300 mm) is achieved using a T-type gantry arrangement, which locates the work table supported on a vacuum preloaded air bearing on top of a reference granite surface. Actuation is provided with direct drives that fulfil the functions of motion controls, stiffness enhancement, and vibration damping. Thermal deformations are mitigated by designing internally cooled motor couplings. The error budget for the stage, as well as multivariable control law design and stability analysis, and metrology results are discussed in the paper.

  • Precision Machine tool X-Y stage utilizing a planar air bearing arrangement
    CIRP Annals - Manufacturing Technology, 2010
    Co-Authors: Kaan Erkorkmaz, J. M. Gorniak, D J Gordon
    Abstract:

    This paper presents a new X-Y stage concept for Precision Machine tools. A large work area (300 mm ?? 300 mm) is achieved using a T-type gantry arrangement, which locates the work table supported on a vacuum preloaded air bearing on top of a reference granite surface. Actuation is provided with direct drives that fulfil the functions of motion controls, stiffness enhancement, and vibration damping. Thermal deformations are mitigated by designing internally cooled motor couplings. The error budget for the stage, as well as multivariable control law design and stability analysis, and metrology results are discussed in the paper. ?? 2010 CIRP.