• Tribology and Lubricants
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• 제12권1호
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• pp.29-35
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• 1996

The static and dynamic stability analysis of air-lubriceted tilting pad journal bearing which considers tilting effect of each pad and preload but neglects pad inertia were performed. And these characteristic analysis were performed with elasticity effect too. A direct numerical method is used in calculating the static characteristics such as load carrying capacity, firction force and perturbation method is used for calculation of dynamic characteristics. The stability analysis was performed with the variation of bearing number, eccentricity ratio and attitude angle considering pad elasticity effect.

• Tribology and Lubricants
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• 제17권6호
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• pp.476-481
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• 2001

This paper has been presented the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existed investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. In this paper, The pressure behavior in theory of air film according to the eccentricity of journal and the source positions analyzed. The theoretical analysis have been identified by experiments. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• 대한기계학회논문집
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• 제14권6호
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• pp.1487-1494
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• 1990

본 연구에서는 공기분자간 평균 자유비형거리(molecular mean free path)를 고려한 수정된 레이놀즈 방정식을 공기막 두께의 미소 교란항에 대하여 전개하여 비선 형 정적 평형방정식과 교란 미분방ㄹ정식을 구하였다. 비선형 정적 평형방정식을 슬 라이더의 정량적인 거동형태를 표시하므로 이를 이용하여 슬라이더의 정적특성을 구할 수 있다. 이에 반하여, 동적 교란미분 방정식은 슬라이더의 간극함수에 대한 각종 교란에 의하여 유발되는 반발압력을 정성적으로 나타내므로, 슬라이더의 외부교란에 대한 응답특성 및 자기복원특성 등을 구할 수 있다. 이러한 특성을 서스펜션에 부착 된 헤드 시스템의 운동방정식에 함께 고려하여 시스템의 동적 특성을 해석하고 슬라이 더의 설계변수가 이에 미치는 영향을 고찰하고저 한다.

• Tribology and Lubricants
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• 제6권1호
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• pp.74-81
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• 1990

The threshold of instability for a rigid rotor supported in externally pressurized airlubricated circular or non-circular journal bearings of finite length is theoretically analyzed. The analysis is performed for a bearing having one feeding plane, no recess volume, which is assumed to be a line source, and is based on a first order perturbation of journal center motion about steady state position. And then linearized system dynamic analysis is carried out. Numerical results are given, showing the threshold of instability as a function of supply pressure ratio, feeding parameter and load. It is shown that the region that 2-lobe bearing is more stable than circular bearing exists and whirl ratio of 2-lobe bearing is less than that of the other types of bearing.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.243-249
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• 2001

This paper has been presented the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existed investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. In this paper, the pressure behavior in theory of air film according to the eccentricity of journal and the source positions analyzed. The theoretical analysis have been identified by experiments. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.990-994
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• 2004

This paper presents a method to predict the transient characteristic of the air lubricated slider head in a hard disk drive by using optimization technique. The time dependent modified Reynolds equation based on the molecular slip flow approximation equations was used to describe the fluid flow within the air bearing and the implicit finite difference scheme is applied to calculate the pressure distribution under the slider head. The exhaustive search combined with the Broyden-Fletcher-Goldfarb-Shanno method were employed to obtain optimum design variables which are taper angle, rail width and taper length in order to keep the forces and moments acting on the slider head in dynamic equilibrium. The results show that the optimal head slider of the magnetic head has good stability characteristic that can reach the steady state within 0.5 microsecond.