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

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.

Numerical Investigation of Static and Dynamic Characteristics of Water Hydrostatic Porous Thrust Bearings

2011 ◽  
Vol 5 (6) ◽  
pp. 773-779 ◽  
Author(s):  
Yuki Nishitani ◽  
◽  
Shigeka Yoshimoto ◽  
Kei Somaya
Keyword(s):  
Porous Material ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Measuring Equipment ◽  
Load Capacity ◽  
Damping Coefficient ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Hydrostatic Bearings ◽  
Aerostatic Bearings

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.

Static and Dynamic Characteristics of Self-Acting, Partial-Arc, Gas Journal Bearings

1964 ◽  
Vol 86 (2) ◽  
pp. 405-413 ◽  
Author(s):  
R. J. Wernick ◽  
C. H. T. Pan
Keyword(s):  
Power Series ◽  
Dynamic Characteristics ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Standard Form ◽  
Journal Bearings ◽  
Static And Dynamic Characteristics ◽  
Stability Derivatives ◽  
Bearing Loads ◽  
Gas Journal Bearing

The Reynolds equation applicable to a self-acting partial-arc gas journal bearing is perturbed in terms of the compressibility number Λ. The resulting set of equations is then put into a standard form and Galerkin’s method is used to obtain bearing loads and stability derivatives. These results are expressed in a power series in Λ.

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

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.

Performance of textured foil journal bearing considering the influence of relative texture depth

2022 ◽  
pp. 135065012110729
Author(s):  
Guanghui Zhang ◽  
Kefan Xu ◽  
Jiazhen Han ◽  
Yanzhong Huang ◽  
Wenjie Gong ◽  
...  
Keyword(s):  
Iterative Method ◽  
Dynamic Characteristics ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Surface Texturing ◽  
Static And Dynamic Characteristics ◽  
Foil Bearing ◽  
Newton Raphson ◽  
Maximum Increment

Both foil structure and surface texturing have been widely used to improve bearing performance. However, there is little research on their combination, namely, textured gas foil bearing. This paper adopts the Reynolds equation as the pressure governing equation of bump-type foil journal bearing to study the influence of textures located on the top foil. The Newton-Raphson iterative method and the perturbation method are employed to obtain static and dynamic characteristics, respectively. Thereafter, based on three texture distribution types, further analysis about the effect of the relative texture depth and the textured portion is carried out. The results indicate that an appropriate arrangement of textures could improve the performance of gas foil bearing. For #1 texture distribution, the maximum increment of load capacity could exceed 10% when ω  =  1.4 × 105 r/min, ε  =  0.2.

Static and Dynamic Characteristics of Externally Pressurized Porous Gas Journal Bearing With Four Degrees-of-Freedom

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Shuyun Jiang ◽  
Shengye Lin ◽  
Chundong Xu
Keyword(s):  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Reynolds Equation ◽  
Static Load ◽  
Journal Bearing ◽  
Load Capacity ◽  
Linear Perturbation ◽  
Static And Dynamic Characteristics ◽  
Bearing Number ◽  
Gas Journal Bearing

This paper studies the static and dynamic coefficients of an externally pressurized porous gas journal bearing. The finite difference method is used to solve the Reynolds equation of the bearing to obtain the static load capacity. The linear perturbation method is adopted to derive the perturbation equations considering four degrees-of-freedom (4DOF), namely, the translational movements in x and y directions and the rotational movements around x and y directions. The effects of various parameters on the dynamic behaviors of the journal bearing are studied. These parameters include the bearing number, the supply pressure, the feeding parameter, the length-to-diameter ratio, the porosity parameter, the eccentricity ratio, and tilting angles. Simulated results prove that the proposed method is valid in estimating the static and dynamic characteristics of a porous gas journal bearing with 4DOF.

Misalignment Effect on the Static and Dynamic Characteristics of Hydrodynamic Journal Bearings

1995 ◽  
Vol 117 (4) ◽  
pp. 717-723 ◽  
Author(s):  
Z. L Qiu ◽  
A. K. Tieu
Keyword(s):  
Dynamic Characteristics ◽  
Reynolds Equation ◽  
Static Load ◽  
Load Capacity ◽  
Vertical Direction ◽  
Journal Bearings ◽  
Static And Dynamic Characteristics ◽  
Flow Friction ◽  
The Stability ◽  
Side Flow

This paper solves the Reynolds equation by the finite difference method in a fixed coordinate system with the static load acted in the vertical direction. All static and dynamic characteristics (including load capacity, attitude angle, side flow, friction force, misaligned moments, and eight linear force coefficients) of a horizontally grooved bearing under different eccentricity and misalignment conditions are presented and compared with available experimental data. The effects of misalignment on all these bearing characteristics and on the stability of the rotor-bearing system are analyzed.

On the Finite Volume Upwind Solution of the Reynolds Equation for a Compressible Fluid

2005 ◽  
Author(s):  
Mihai Arghir ◽  
Se´bastien Le Lez ◽  
Jean Frene
Keyword(s):  
Numerical Solution ◽  
Finite Volume ◽  
Dynamic Characteristics ◽  
Compressible Fluid ◽  
Potential Flow ◽  
Reynolds Equation ◽  
Unstructured Grids ◽  
Finite Volumes ◽  
Static And Dynamic Characteristics ◽  
Finite Volume Discretization

The present work deals with the numerical solution of the compressible Reynolds equation in the frame of the finite volumes method of discretization. The first original aspect of the numerical solution is a new upwind procedure borrowed from aerodynamics, namely from the transonic potential flow solutions. The second original aspect of the numerical solution is the finite volume discretization for unstructured grids. The method was developed in an effort to obtain a tool for analyzing hybrid bearings so its first validations consists of comparisons between calculated static and dynamic characteristics and values found in the literature.

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

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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