A Computational Modeling Reflecting Static and Dynamic Characteristics of LM Bearings for Machine Tools

A moving table supported by aerostatic bearings can achieve excellent accuracy of motion because of its noncontact support and, hence, it is used in various precision machine tools and measuring equipment. However, because of low viscosity of air, the damping coefficient of aerostatic bearings is not very high, causing vibration with nanometer-order amplitudes. The accuracy of machine tools and measuring equipment could deteriorate because of this vibration. It is expected that water hydrostatic bearings would have a higher damping coefficient than aerostatic bearings due to the higher viscosity of water. In addition, water, like air, does not pollute the environment. In this paper, the static and dynamic characteristics of water hydrostatic thrust bearings using porous material were numerically investigated and comparedwith conventional pocket hydrostatic bearings with a capillary restrictor. Hydrostatic porous bearings can be easily constructed because the porous material becomes a viscous restrictor itself. It was consequently found that water hydrostatic porous thrust bearings have higher maximum load capacity and slightly lower stiffness than water bearings with a capillary restrictor.

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Optimized Design and Performance Study of High Speed Five-Axis Machine Tools

Volume 6: 25th Design for Manufacturing and the Life Cycle Conference (DFMLC) ◽

10.1115/detc2020-22253 ◽

2020 ◽

Author(s):

Tzu-Chi Chan ◽

Jyun-Sian Yang

Keyword(s):

Machine Tool ◽

Dynamic Characteristics ◽

Machine Tools ◽

High Speed ◽

Spectral Response ◽

Work Piece ◽

Static And Dynamic Characteristics ◽

Five Axis ◽

Speed Accuracy ◽

Machine Structure

Abstract With the development of machine tools trending toward high precision, intelligence, multi-axis, and high speed, the improvement of the processing performance and rigidity of the machine is considerably important. The objective of this study is to design of a high-speed five-axis moving-column machine tool and perform structural analysis and optimization. We study the static and dynamic characteristics of the five-axis machine tool, design and improve the mechanical structure, and optimize the structural configuration of the machine. The entire machine structure is further analyzed and enhanced to improve its static and dynamic characteristics, including static rigidity, modal, transient, and spectral response characteristics. The static and dynamic characteristics of the machine structure directly affect the machine processing performance, and further affect the work piece precision machined by the tool. Through this study, the design technology for speed, accuracy, and surface roughness of the machine tool are further improved.

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Effect of Pitch Error on Static and Dynamic Characteristics of Hydrostatic Worm-Rack-Drive

Journal of Tribology ◽

10.1115/1.4049619 ◽

2021 ◽

Vol 143 (11) ◽

Author(s):

Yongtao Zhang ◽

Yupeng Liu ◽

Junjun Deng ◽

Rongxiang Song ◽

Yingdan Zhu

Keyword(s):

Dynamic Characteristics ◽

Performance Optimization ◽

Machine Tools ◽

Continuity Equation ◽

Reynolds Equation ◽

Axial Stiffness ◽

Static And Dynamic Characteristics ◽

Pitch Error ◽

And Performance ◽

Numerical Calculation Method

Abstract Hydrostatic worm-rack-drive has obvious advantages on large-sized machine tools, and its performance is significantly affected by pitch errors. This paper theoretically researches the axial static and dynamic characteristics of hydrostatic worm-rack-drive, including the effects of the amplitude, period, and phase of pitch errors. Based on the expanded view of the helicoid of threads, a numerical calculation method is implemented where the Reynolds’ equation and flow continuity equation are solved simultaneously. The influence rule of pitch errors on pocket pressure, flow, axial fluid-film force, axial stiffness coefficient, and axial damping coefficient are discussed in detail, for providing beneficial guidance for the design and performance optimization of hydrostatic worm-rack-drive.

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Static and Dynamic Characteristics of Machine Tools with an Adhesive–Mechanical Support System

Russian Engineering Research ◽

10.3103/s1068798x21070170 ◽

2021 ◽

Vol 41 (7) ◽

pp. 645-648

Author(s):

Yu. V. Maksimov ◽

R. A. Musatov

Keyword(s):

Support System ◽

Dynamic Characteristics ◽

Machine Tools ◽

Mechanical Support ◽

Static And Dynamic Characteristics

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Effect of Time-Varying Moving Structures on the Spatial Accuracy of Five-Axis Machine Tools

10.21203/rs.3.rs-298304/v1 ◽

2021 ◽

Author(s):

Tzu-Chi Chan ◽

Jyun-Sian Yang

Keyword(s):

Machine Tool ◽

Dynamic Characteristics ◽

Machine Tools ◽

High Speed ◽

Time Varying ◽

Spatial Accuracy ◽

Static And Dynamic Characteristics ◽

Five Axis ◽

Speed Accuracy ◽

Machine Structure

Abstract Machine tools are constantly in motion during machining; however, studies have not considered the effect of the dynamic and static characteristics of the machine caused by the movement of the structure over time. In this study, the time-varying moving structure in the spatial coordinate arm is analyzed to improve the spatial accuracy of the motion of a five-axis machine tool in the cutting area. The objective is to design a high-speed five-axis moving-column machine tool and to perform structural analysis of spatial accuracy. We studied the static and dynamic characteristics of a five-axis machine tool, designed and improved its mechanical structure, and optimized its structural configuration. With further analysis, the entire machine structure was enhanced to improve its static and dynamic characteristics. The static and dynamic characteristics of the machine structure were found to directly affect its processing performance and the precision of the workpiece machined by the tool. Through this study, the design technology for speed, accuracy, and surface roughness of the machine tool was further improved.

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