Stability of Water-Lubricated, Hydrostatic, Conical Bearings With Spiral Grooves for High-Speed Spindles

2001 ◽  
Vol 124 (2) ◽  
pp. 398-405 ◽  
Author(s):  
S. Yoshimoto ◽  
S. Oshima ◽  
S. Danbara ◽  
T. Shitara
Keyword(s):  
High Speed ◽  
Water Pressure ◽  
Rotating Shaft ◽  
Pressurized Water ◽  
High Speeds ◽  
Theoretical Predictions ◽  
The Stability ◽  
Stability Of Water ◽  
Spiral Grooves ◽  
Good Agreement

In this paper, the stability of water-lubricated, hydrostatic, conical bearings with spiral grooves for high-speed spindles is investigated theoretically and experimentally. In these bearing types, pressurized water is first fed to the inside of the rotating shaft and then introduced into spiral grooves through feeding holes located at one end of each spiral groove. Therefore, water pressure is increased due to the effect of the centrifugal force at the outlets of the feeding holes, which results from shaft rotation. In addition, water pressure is also increased by the viscous pumping effect of the spiral grooves. The stability of the proposed bearing is theoretically predicted using the perturbation method, and calculated results are compared with experimental results. It was consequently found that the proposed bearing is very stable at high speeds and theoretical predictions show good agreement with experimental data.

Axial Load Capacity of Water-Lubricated Hydrostatic Conical Bearings With Spiral Grooves (On the Case of Rigid Surface Bearings)

1996 ◽  
Vol 118 (4) ◽  
pp. 893-899 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Anno ◽  
M. Tamura ◽  
Y. Kakiuchi ◽  
K. Kimura
Keyword(s):  
High Speed ◽  
Printed Circuit Boards ◽  
Load Capacity ◽  
Water Pressure ◽  
Circuit Boards ◽  
The Finite Element Method ◽  
Rotating Shaft ◽  
Pressurized Water ◽  
Axial Load Capacity ◽  
Spiral Grooves

This paper describes the static characteristics of water-lubricated hydrostatic conical bearings with spiral grooves. Hydrostatic conical bearings treated here have been designed for high speed spindles and are intended to apply to spindles for drilling small holes of printed circuit-boards. Pressurized water is first fed to the inside of the rotating shaft and supplied to spiral grooves on the shaft surface through feeding holes. Therefore, water pressure is greatly increased at outlets of feeding holes due to the centrifugal force by shaft rotation. Furthermore, water pressure is also increased by the viscous pump effect of spiral grooves. Water pressures in the bearings under concentric condition are numerically obtained by using the finite element method and calculated results are compared with experimental ones. It is consequently found that this water-lubricated hydrostatic conical bearings with spiral grooves are very suitable for precision high speed spindles.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

Theoretical Prediction of Motions of High-Speed Planing Boats in Waves

1978 ◽  
Vol 22 (03) ◽  
pp. 140-169
Author(s):  
Milton Martin
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Nonlinear Effects ◽  
Theoretical Method ◽  
Valuable Insight ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Response Amplitude Operators ◽  
Phase Angles ◽  
Good Agreement

A theoretical method is derived for predicting the linearized response characteristics of constant deadrise high-speed planing boats in head and following waves. Comparisons of the theoretical predictions of the pitch and heave response amplitude operators and phase angles with existing experimental data show reasonably good agreement for a wide variety of conditions of interest. It appears that nonlinear effects are more severe at a speed to length ratio of 6 than of, say, 4 or less, principally because of the reduction of the damping ratio of the boat with increasing speed, and the consequent increase in motions in the vicinity of the resonant encounter frequency. However, it is concluded that the linear theory can provide a simple and fast means of determining the effect of various parameters such as trim angle, deadrise, loading, and speed on the damping, natural frequency, and linearized response in waves, and that this can furnish valuable insight into the actual boat dynamics, even though the accurate predictions of large motions and peak accelerations would require a nonlinear analysis.

Some Limitations in Applying Classical EHD Film Thickness Formulas to a High-Speed Bearing

1981 ◽  
Vol 103 (2) ◽  
pp. 295-301 ◽  
Author(s):  
J. J. Coy ◽  
E. V. Zaretsky
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Heating Effects ◽  
Theoretical Predictions ◽  
Traction Fluid ◽  
Shear Heating ◽  
Thickness Measurements ◽  
Inner Race ◽  
Maximum Stresses ◽  
Good Agreement

Elastohydrodynamic film thickness was measured for a 20-mm ball bearing using the capacitance technique. The bearing was thrust loaded to 90, 448, and 778 N (20, 100, and 175 lb). The corresponding maximum stresses on the inner race were 1.28, 2.09, and 2.45 GPa (185,000, 303,000, and 356,000 psi). Test speeds ranged from 400 to 14,000 rpm. Film thickness measurements were taken with four different lubricants: (a) synthetic paraffinic, (b) synthetic paraffinic with additives, (c) neopentylpolyol (tetra) ester meeting MIL-L-23699A specifications, and (d) synthetic cycloaliphatic hydrocarbon traction fluid. The test bearing was mist lubricated. Test temperatures were 300, 338, and 393 K. The measured results were compared to theoretical predictions using the formulae of Grubin, Archard and Cowking, Dowson and Higginson, and Hamrock and Dowson. There was good agreement with theory at low dimensionless speed, but the film was much smaller than theory predicts at higher speeds. This was due to kinematic starvation and inlet shear heating effects. Comparisons with Chiu’s theory on starvation and Cheng’s theory on inlet shear heating were made.

Dynamic Stability of the Rotating Shaft Made of Boltzmann Viscoelastic Solid

1986 ◽  
Vol 53 (2) ◽  
pp. 424-429 ◽  
Author(s):  
W. Zhang ◽  
F. H. Ling
Keyword(s):  
Dynamic Stability ◽  
High Speed ◽  
Static Load ◽  
Viscoelastic Solid ◽  
Rotating Shaft ◽  
Special Cases ◽  
Analytical Formulas ◽  
Rotating Shafts ◽  
The Stability ◽  
Inclined Angle

A general theory is developed in this paper for studying the dynamic stability of high-speed nonuniform rotating shafts made of a Boltzmann viscoelastic solid. The equation of motion of the shaft is deduced. The stability criteria are derived by using this equation. The unstable regions for a nonhomogeneous viscoelastic shaft are worked out numerically. Analytical formulas are also given in this paper for determining the planar deflection of the shaft and its inclined angle due to a planar static load. The conclusions for special cases given in the literature known to the authors are all covered by the results in this paper.

Theory of High-Speed Displacement Ships with Transom Sterns

1986 ◽  
Vol 30 (03) ◽  
pp. 186-193
Author(s):  
Marshall P. Tulin ◽  
C. C. Hsu
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Parametric Form ◽  
High Speeds ◽  
New Finding ◽  
Good Agreement

A theory has been developed for high-speed displacement ships with transom sterns; it treats the hull as finite in beam and draft, but slender. The flow is assumed to be smooth at the aft waterline and to have a trailing wake. The trailing wake results in substantial residuary resistance at high speeds for normal waterline ships. This is a completely new finding. Calculations are made for ships of highly variable parametric form and the results are given. This residuary is typically reduced by widening the transom. A shallow draft at the transom is also indicated. A comparison of calculated results with existing experimental data shows good agreement.

scholarly journals Using the Schwarz Alternating Method to Identify Critical Water-Resistant Thickness between Tunnel and Concealed Cavity

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Jiaqi Guo ◽  
Jianxun Chen ◽  
Fan Chen ◽  
Shanxiu Huang ◽  
Hongyu Wang
Keyword(s):  
Critical Thickness ◽  
Lateral Pressure ◽  
Water Pressure ◽  
Pressure Coefficient ◽  
Strength Criterion ◽  
Pressurized Water ◽  
Schwarz Alternating Method ◽  
Alternating Method ◽  
Analytical Result ◽  
The Stability

This paper aims to estimate the stability of the water-resistant strata between the tunnel and the small-medium-sized concealed cavity filled with high-pressurized water or other fillings at optional position around tunnel through solving the double-hole problem. The analytical method to identify the critical water-resistant thickness is proposed based on the Schwarz alternating method and Griffith strength criterion, and the program to calculate the critical thickness was prepared according to this method using mathematical software. Parametric study of the critical thickness indicates that the critical water-resistant thickness will increase with the buried depth of the tunnel and cavity size; the lateral pressure coefficient has more complicated influence on the critical thickness, which is affected by cavity position; when the cavity is filled with sand or gravel, the critical water-resistant thickness will decrease with the increase of the filling pressure; and when the cavity is filled with the high-pressurized water, the critical thickness will decrease as the water pressure initially and increase afterwards. The analytical result of the critical thickness is consistent with that obtained by numerical simulation using the user-defined program based on FLAC3D, demonstrating the rationality and feasibility of the proposed method in this study.

Schlieren and Shadowgraph Images of Transient Expanding Spherical Thin Flames

2002 ◽  
Author(s):  
Matyas Matlo ◽  
Farzan Parsinejad ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Ccd Camera ◽  
Cylindrical Chamber ◽  
Spherical Flames ◽  
Cellular Flames ◽  
Experimental Facilities ◽  
The Stability ◽  
Light Beams ◽  
Optical Behavior ◽  
Good Agreement

Experimental facilities have been built to visualize transient expanding spherical flames. Facilities include a cylindrical chamber with two end glasses for optical observation. Shadowgraph and Schlieren pictures of flame propagation have been taken using a high speed Charged Coupled Device (CCD) camera. In this paper the optical behavior of spherical flames has been investigated using both Schlieren and Shadowgraph methods. A mathematical model has been developed to predict the intensity of refracted light beams interacting with a transient expanding thin flame. Experimental results are in very good agreement with theoretical model. Schlieren and Shadowgraph techniques have also been used to view smooth, cracked and cellular flames, which are useful in determining the stability of propagating flame.

scholarly journals Study on Dynamic Evaluation Method of Stability of Slope Controlled by Structural Plane Based on Deformation Characteristics

2021 ◽  
Vol 283 ◽  
pp. 01047
Author(s):  
Qun Luo ◽  
Tianlong Zhao
Keyword(s):  
High Speed ◽  
Evaluation Method ◽  
Deformation Characteristics ◽  
High Speed Railway ◽  
Structural Plane ◽  
Dynamic Evaluation ◽  
Stability Of Slope ◽  
Measured Displacement ◽  
The Stability ◽  
Good Agreement

The study on deformation characteristics of structural plane is the research foundation of structural plane mechanics and hydraulics. In this paper, a calculation method for dynamic evaluation of the stability of slope controlled by structural plane based on deformation characteristics was proposed on the basis of shear reinforcement three-fold line constitutive model, and it was applied to the example of Raytheon landslide in Chongqing-Guizhou high-speed railway. By comparison, the calculated results were in good agreement with the measured displacement results, and the displacement development process of the dangerous rock mass can be well simulated, thus verifying the feasibility and engineering practicality of the method.

Pumping Characteristics of a Herringbone-Grooved Journal Bearing Functioning as a Viscous Vacuum Pump

1999 ◽  
Vol 122 (1) ◽  
pp. 131-136 ◽  
Author(s):  
S. Yoshimoto ◽  
Y. Ito ◽  
A. Takahashi
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Slip Flow ◽  
Laser Scanner ◽  
Vacuum Pump ◽  
Chamber Pressure ◽  
Design Parameters ◽  
Theoretical Predictions ◽  
Flow Effects ◽  
Good Agreement

A laser scanner motor with low power and high speed has been developed. This scanner motor uses a herringbone-grooved journal bearing which functions as a viscous vacuum pump. The windage power loss of a polygon mirror is reduced, since the air inside the pump housing is pumped out by herringbone-grooved viscous vacuum action. In this paper, the theoretical pumping characteristic of this bearing is investigated, using the narrow-groove theory and accounting for first-order slip flow. The effects of various design parameters on the pumping characteristics are discussed. Optimum geometric design parameters were found to obtain the minimum inner chamber pressure of the housing. The theoretical predictions considering slip flow effects are in good agreement with experimental measurements. [S0742-4787(00)01801-4]

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