Effect of an Hourglass-Shape Tapered Sleeve on the Performance of the Fluid Dynamic Bearings of a HDD Spindle Motor

2013 ◽  
Author(s):  
J. H. Lee ◽  
M. H. Lee ◽  
G. H. Jang
Keyword(s):  
Rough Surface ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Rotating Disk ◽  
Groove Depth ◽  
Spindle Motor ◽  
Spindle System ◽  
Thrust Bearings ◽  
Steel Sleeve ◽  
Bearing Ball

Fluid dynamic bearings (FDBs) of a HDD spindle motor support the rotating disk-spindle system through the pressure generated in the fluid lubricant. The radial and axial clearances of a 2.5″ HDD spindle motor are approximately 2 and 30 micro-meters, respectively, and herringbone or spiral grooves are inscribed in the sleeve of journal or thrust bearings to provide pumping pressure. One of the difficult manufacturing processes is to inscribe uniform grooves, especially groove depth in the range of several micro meters. Grooves are inscribed on the surface of the stainless steel sleeve by the electro chemical machining (ECM) which generally generates rough surface of the sleeve in grooved bearing. Ball-sizing process is used to scrape down rough surface. When a ball passes through the sleeve of FDBs to make rough surface smooth, compressive pressure is generated between ball and sleeve inlet and between ball and sleeve outlet, respectively. It forms an hourglass-shape tapered sleeve as shown in Figure 1, and tapered sleeve generally decreases the static and dynamic performance of the FDBs and the HDD spindle system, consequently.

Noise and Vibration Originated From UMF due to Rotor Eccentricity of the HDD Spindle System

2013 ◽  
Author(s):  
S. J. Sung ◽  
G. H. Jang ◽  
K. J. Kang
Keyword(s):  
Degrees Of Freedom ◽  
Acoustic Noise ◽  
Fluid Dynamic ◽  
Rotating Disk ◽  
Spindle Motor ◽  
Noise And Vibration ◽  
Spindle System ◽  
Cogging Torque ◽  
Outer Rotor ◽  
Numerical And Analytical Methods

Cogging torque and UMF (unbalanced magnetic force) are major excitation sources of acoustic noise and vibration originated from HDD spindle motors. They are generally outer rotor type motors with fluid dynamic bearings (FDBs). The FDBs support and constrain the rotating disk-spindle system in five degrees of freedom except axial rotating direction. Unbalanced mass of the disk-spindle system generates whirling motion and changes the characteristics of UMF. Several researchers have investigated the harmonic contents of cogging torque and UMF by numerical and analytical methods [1]–[3]. Lee and Jang [4] experimentally and numerically investigated the characteristics of the UMF of a HDD spindle motor due to manufacturing errors such as the uneven magnetization of permanent magnet (PM) and the eccentricity of rotor and stator. However, they discussed only the cogging torque and UMF, and did not investigate the effect of the cogging torque and UMF on acoustic noise and vibration of a HDD spindle system.

Monte Carlo Simulation of the Manufacturing Tolerance of FDBs to Identify the Sensitive Design Variables Affecting the Performance of a Disk-Spindle System

2014 ◽  
Author(s):  
J. H. Lee ◽  
M. H. Lee ◽  
H. K. Jang ◽  
G. H. Jang
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Journal Bearing ◽  
Fluid Dynamic ◽  
Critical Mass ◽  
Groove Depth ◽  
Friction Torque ◽  
Spindle System ◽  
Manufacturing Tolerance ◽  
Design Variables

This research investigates the Monte Carlo simulation of manufacturing tolerance of FDBs to identify the sensitive design variables for the friction torque of fluid dynamic bearings (FDBs) and the critical mass of disk-spindle system supported by FDBs. We analyze the characteristics according to design variables of FDBs and it shows that the clearance of journal bearing is most sensitive design variable of both friction torque and critical mass. Also the groove to groove and ridge ratio and groove depth of grooved journal bearing which are manufactured by ECM are also sensitive to determine the friction torque and the critical mass of the FDBs, respectively. This research can be utilized to manage manufacturing tolerance to maintain the consistent performance of FDBs and a disk-spindle system in a HDD.

scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

Fluid dynamic bearing for HD-DVD single-phase spindle motor

2003 ◽  
Author(s):  
Hung-Kuang Hsu ◽  
Chien-Chang Wang ◽  
Mei-Lin Lai ◽  
Yu-Hsiu Chang ◽  
Der-Ray Huang
Keyword(s):  
Single Phase ◽  
Fluid Dynamic ◽  
Spindle Motor ◽  
Fluid Dynamic Bearing

Groove Shape Optimization of Thrust Air Bearing for Small Size Spindle Considering the Processing Errors

2018 ◽  
Author(s):  
Masayuki Ochiai ◽  
Naoya Kato ◽  
Hiromu Hashimoto
Keyword(s):  
Probability Distribution ◽  
Laser Processing ◽  
Thrust Bearing ◽  
Groove Depth ◽  
Spindle Motor ◽  
Processing Method ◽  
Optimum Shape ◽  
Air Bearing ◽  
Machining Error ◽  
Processing Errors

In this research, we aim to examine the usefulness of the newly developed spindle motor proposed by Ochiai. Since machining error due to tool wear etc. used for microfabrication can be ignored, laser processing was used as a processing method. Thrust bearing grooves were generated by laser processing, and variation in groove depth was observed. Finally, the optimum shape of the thrust bearing groove was obtained by robust optimization using the probability distribution that can be approximated from the obtained machining error.

Virtual Evaluation for Machine Tool Design

2008 ◽  
Author(s):  
Masahiko Mori ◽  
Zachary I. Piner ◽  
Ke Ding ◽  
Adam Hansel
Keyword(s):  
Machine Tool ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Digital Simulation ◽  
Machining Accuracy ◽  
Analysis Model ◽  
Simulation Accuracy ◽  
Theoretical Simulation ◽  
Physical Experiments ◽  
Static Rigidity

This paper presents the virtual machine tool environment Mori Seiki established for the evaluation of static, dynamic, and thermal performance of Mori Seiki machine tools. In this system environment, machining accuracy and quality are the main focus for each individual analysis discipline. The structural analysis uses the Finite Element Method (FEM) to monitor and optimize the static rigidity of the machine tool. Correlation between physical experiments and digital simulation is conducted to validate and optimize the static simulation accuracy. To accurately evaluate and effectively optimize dynamic performance of the machine tool in the virtual environment, the critical modal parameters such as damping and stiffness are calibrated based on experimental procedures which results in precise setup of the frequency response models. Computational Fluid Dynamic (CFD) analysis model is built in the environment so that the thermal perspective of the machine tool is evaluated and thermal deformation is monitored. This paper demonstrates compatibility of the digital simulation with physical experiments and success in integrating theoretical simulation processes with practical Mori Seiki machine tool development.

On the Optimum Groove Geometry for Herringbone Grooved Journal Bearings

2006 ◽  
Vol 128 (3) ◽  
pp. 585-593 ◽  
Author(s):  
A. M. Gad ◽  
M. M. Nemat-Alla ◽  
A. A. Khalil ◽  
A. M. Nasr
Keyword(s):  
Groove Depth ◽  
Radial Force ◽  
Journal Bearings ◽  
Friction Torque ◽  
Performance Characteristics ◽  
Width Ratio ◽  
Geometrical Parameters ◽  
Thrust Bearings ◽  
Circular Groove ◽  
Groove Profile

Recently, herringbone-grooved journal bearings have had important applications in miniature rotating machines. The scribed grooves, on either the rotating or stationary member of the bearing, can pump the lubricant inward, which generates supporting stiffness and improves the dynamic stability, especially for concentric operation. Most of the previous investigations that dealt with herringbone grooved journal bearings and grooved thrust bearings were theoretical. Few experimental attempts for the investigation of the performance characteristics of herringbone grooved journal bearings (HGJBs) and grooved thrust bearings have been done. All these investigations concentrated on rectangular and circular groove profiles of HGJBs. In order to improve the performance characteristics of HGJBs, a new design of the groove profile, the beveled-step groove profile, is introduced. The introduced groove profile is capable of increasing the pressure recovery at the divergence of the flow over the step. In addition, it increases the amount of oil pumped inward over the circular groove profile. Optimization processes were carried out experimentally, in order to obtain the optimal geometry of the introduced groove profile. The optimum geometrical parameters of the groove (groove angle α, groove width ratio β, and groove depth ratio Γ) are 29deg, 0.5, and 2.0, respectively, which give maximum radial force and maximum radial stiffness of the beveled-step HGJB. In order to check the effectiveness of the introduced beveled-step groove profile, the obtained results were compared with that for rectangular groove profile. The comparison shows that the introduced beveled-step HGJBs have higher radial force, higher load carrying capacity, and lower friction torque than the rectangular HGJBs.

Numerical analysis of the dynamic performance of aerostatic thrust bearings with different restrictors

2018 ◽  
Vol 233 (3) ◽  
pp. 406-423 ◽  
Author(s):  
Hailong Cui ◽  
Yang Wang ◽  
Xiaobin Yue ◽  
Yifei Li ◽  
Zhengyi Jiang
Keyword(s):  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Dynamic Mesh ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
The Impact ◽  
The Relationship

This study utilizes a dynamic mesh technology to investigate the dynamic performance of aerostatic thrust bearings with orifice restrictor, multiple restrictors, and porous restrictor. An experiment, which investigates the bearing static load capacity, was carried out to verify the calculation accuracy of dynamic mesh technology. Further, the impact of incentive amplitude, incentive frequency, axial eccentricity ratio, and non-flatness on the bearing dynamic performance was also studied. The results show incentive amplitude effect can be ignored at the condition of amplitude less than 5% film thickness, while the relationship between dynamic characteristics and incentive frequency presented a strong nonlinear relationship in the whole frequency range. The change law of dynamic stiffness and damping coefficient for porous restrictor was quite different from orifice restrictor and multiple restrictors. The bearing dynamic performance increased significantly with the growth of axial eccentricity ratio, and the surface non-flatness enhanced dynamic performance of aerostatic thrust bearings.

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