• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1999년도 제30회 추계학술대회
• /
• pp.146-153
• /
• 1999

A numerical dynamic simulation is necessary to investigate the capacity of the HDD. The slider surface become more and more complicated to make the magnetized area smaller and readback signal stronger. So a numerical dynamic simulation must be preceded to develop a new slider in HDD. The dynamic simulations of air-lubricated slider bearing have been peformed using FIFD(Factored Implicit Finite Difference) method. The governing equation, Reynolds equation Is modified with Fukui and Kaneko model(FK model) which includes the first and the second-order slip. The equations of motion for the slider bearing are solved simultaneously with the modified Reynolds equation for the case of three degrees of freedom. The slider transient response for disk step bump and slider impulse force is given for various case and for iteration algorithm and new algorithm.

• Tribology and Lubricants
• /
• 제14권4호
• /
• pp.64-71
• /
• 1998

In this study deals with measurement of the vibration amplitudes of rotor-bearing system supported by foil bearing were performed experimentally, and the stability of the system were analyzed by using those results. Considering initial operating friction, compare bearing lubricated with only air and bearing surface lubricated with oil. Analyzing the transient data, the understanding of the characteristics fur startup and shutdown of rotor-bearing system are available and the dynamic characteristics of the system also can be analyzed exactly.

• 대한기계학회논문집A
• /
• 제27권3호
• /
• pp.343-348
• /
• 2003

In this study, optimum designs of the air-bearing surface (ABS) are achieved using the reduced basis concept which can effectively reduce the number of design variables without cutting down on the design space. Even though the optimization method is easier and more applicable to handle than the trial-and-error method, its efficiency is largely dependent on the number of the design variables. Hence, the reduced basis concept is applied, by which the desired design can be defined as a linear combination of basis designs. The simulation results show the effectiveness of the proposed approach by obtaining the optimum solutions of the sliders whose target flying heights are 25, 20, and 15nm.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.605-608
• /
• 1997

In this paper, the case study of reducing rotational errors is done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and ed nonlinear dynamics of electromagnets. For the most case, the electrical runout of sensor target is big even in well-finished surface; this runout can cause a rotation error amplified by feedback control system. The adaptive feedforward method based on LMS algorithm is discussed to compensate this kind of runout effects, and investigated its effectiveness by numerical simulation and experimental analysis. The rotor orbit size in both bearings is reduced about to 5 pin due to lX rejection by feedforward control up to 50,000 rpm.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 I
• /
• pp.52-57
• /
• 2001

In this paper, the optimum designs of air-bearing surface(ABS) are achieved effectively by using reduced basis concept which can reduce the number of design variables although the design space is distended. Generally, the optimization method is more effective than the trial and error. However, the efficiency of the former is largely dependent on the number of the design variables. In order to reduce the number of design variables and increase the efficiency, reduced basis concept is applied. We can define the desired design as a linear combination of basis designs using this concept. From this optimization method with reduced basis concept, we easily obtain the optimum designs of ABS whose target flying heights are 25, 20, 15 nm.

• International Journal of Precision Engineering and Manufacturing
• /
• 제8권2호
• /
• pp.26-31
• /
• 2007

A novel scanning probe measurement system was developed to enable precise profile measurements of microaspheric surfaces. An air-bearing stylus with a microprobe was used to perform the surface profile scanning. The new system worked in a contact mode and had the capability of measuring micro-aspheric surfaces with large tilt angles and complex profiles. Due to limitations resulting from the contact mode, such as possible damage caused by the contact force and lateral resolution restrictions from the curvature of the probe tip, several system improvements were implemented. An air bearing was used to suspend the shaft of the probe to reduce the contact force, enabling fine adjustments of the contact force by changing the air pressure. The movement of the shaft was measured by a linear encoder with a scale attached to the actual shaft to avoid Abbe errors. A $50-{\mu}m-diameter$ glass sphere was bonded to the tip of the probe to improve the lateral resolution of the system. The maximum contact force of the probe was 10 mN. The shaft was capable of holding the probe continuously if the contact force was less than 40 mN, and the resolution of the probe could be as high as 10 nm, The performance of the new scanning probe measurement system was verified by experimental data.

• 마이크로전자및패키징학회지
• /
• 제7권4호
• /
• pp.37-42
• /
• 2000

고성능과 고속화의 면에서 광저장장치의 관심은 상당히 높다. 그러나 하드디스크와 비교하여 광저장장치는 임의의 데이터에 대한 탐색속도가 매우 늦다. 따라서, 광저장장치에서의 새로운 형태의 연구가 필요하다. 본 연구는 하드디스크 장치와 유사한 스윔 암 구동기를 사용한 광저장장치의 공기베어링의 특성에 관해 연구하였다. 광저장장치에서 요구되어지는 최적의 슬라이더 형상을 구하기 위하여 공기 베어링면의 형상변화에 따른 부상상태에 관한 민감도를 연구하였다.

• 한국생산제조학회지
• /
• 제23권4호
• /
• pp.392-397
• /
• 2014

Recently, there is an increase in the need for precision linear stages with vacuum compatibility in such areas as lithography equipment for wafer or mask manufacturing, mask mastering equipment for optical data storage and electron beam equipment. A simple design, high stiffness and low cost can be achieved by using ball bearings. However, a ball bearing have friction and wear problems just as in ambient air. In order to decrease the friction, a special finish, a diamond-like carbon (DLC) film coating, is applied to the surface of a guide rail by sputtering deposition. This paper presents the result of an experimental investigation on the control performance of a ball bearing-guided linear motion stage under two environmental conditions: in air and vacuum. A comparison between the results with and without the DLC coating was also considered in the experimental investigation.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
• /
• pp.425-426
• /
• 2002

Lineal and angular movements of many engine components make the lubricant absorb air and the aerated lubricant greatly influences the clearance performance of contacting behaviors of engine components such as big-end bearing, cam and tappet, etc. This study investigates the behaviors of aerated lubricant in the gap between con-rod bearing and proceeding which is one of the most frictional energy consuming components in the engine. Our assumption for the analysis of aerated lubricant film is that the film formation is influenced by the two major factors. One is the density characteristics of the lubricant due to the volume change of lubricant by absorbing the bubbles and the other is the viscosity characteristics of the lubricant due to the surface tension of the bubble in the lubricant. In our investigation, it is found that these two major factors surprisingly increase the load capacity in certain ranges of bubble sizes and densities. Frictional forces are also influenced by the aerated bubble size and density, which eventually enlarge the shear resistance due the surface tension, Modified Reynolds' equation is developed for the computation of fluid film pressure with the effects of aeration ratio under the dynamic loading condition. From the calculated load capacity by solving modified Reynolds' equation, proceeding locus is computed with Mobility method at each time step.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.590-595
• /
• 2006

This paper presents the friction and anti-wear characteristics of nano-oil with a mixture of a refrigerant oil and carbon nano-particles in the thrust slide-bearing of scroll compressors. Frictional loss in the thrust slide-bearing occupies a large part of total mechanical loss in scroll compressors. The characteristics of friction and anti-wear using nano-oil are evaluated using the thrust bearing tester for measuring friction surface temperature and the coefficient of friction at the thrust slide-bearing as a function of normal loads up to 4,000 N and orbiting speed up to 3,200 rpm. It is found that the coefficient of friction increases with decreasing orbiting speed and normal force. The friction coefficient of carbon nano-oil is 0.015, while that of pure oil is 0.023 under the conditions of refrigerant gas R-22 at the pressure of 5 bars. It is believed that carbon nano-particles can be coated on the friction surfaces and the interaction of nano-particles between surfaces can be improved the lubrication in the friction surfaces. Carbon nano-oil enhances the characteristics of the anti-wear and friction at the thrust slide-bearing of scroll compressors.