• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.4
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• pp.99-107
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• 2000

In this study, a static and dynamic characteristics analysis system for machine tool spindle systems with 3 lobe sliding bearing is developed based on Timoshenko theory, finite element method and windows programming techniques. And the characteristics value of 3 lobe sliding bearing such as eccentricity ratio, attitude angle, friction coefficient , stiffness coefficients, damping coefficients and so on, are determined by using the thermal equilibrium conditions of spindle systems. Since the developed system has various analysis modules related to static deformation analysis, modal analysis, frequency responses analysis and so on, it can be utilized to perform systematically the design an devaluation process of spindle systems with 3 lobe sliding bearing under windows GUI environment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.117-120
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• 2003

A method for PID controller tuning based on process models for unstable processes was introduced. The optimal. proportional and derivative gains of the AMBs were determined by the tuning method and utilized for the chatter stability analysis in order to search for the chatter-free cutting region. The stability analysis results showed that the optimal gains give wider chatter-free cutting region, and as a result the proposed tuning method was confirmed to be an effective tuning method for determining the optimal gains of the AMBs.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.23-29
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• 2001

Cylindrical type of self-controlled restrictor are designed for hydrostatic bearing of grinding wheel spindle. Typical hydrostatic journal bearing with the designed restrictor is analytically model. According to the model, the affect of oper-ation parameters, such as, initial cross distance, supply pressure, diameter of two supply holes, pre-load of spring, and clearance between spindle and housing, on bearing stiffness are analyzed. From the results of the analysis, the optimum conditions of operation parameters that maximize the bearing stiffness are estimated.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.233-243
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• 1998

The demand of high speed machining is increasing due to the high speed cutting and grinding provides high efficiency of process, short process time, improved metal removal capacity and better surface finish. Active magnetic bearings allow much high surface speed than conventional ball bearings and therefore greatly suitable for high speed cutting or grinding. This paper describes a design process of an active magnetic bearing system for a high speed grinding spindle with power 5.5kW and maximum speed 60,000rpm. Magnetic actuators are designed by the magnetic circuit theory considering static load condition, and examined with FEM analysis. Dynamic characteristics are also considered, such as bandwidth, stiffness, natural frequency and static deflection. System characteristics are simulated with a rigid rotor model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1767-1776
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• 2001

For the stable operation of high speed air spindle, the low rotational inertia and high damping ratio of spindle shafts as well as high fundamental natural frequency are indispensable. Conventional steel spindles are net appropriate for very high speed operation because of their high rotational inertia and low damping ratio. In this study, a high speed spindle composed of carbon fiber epoxy composite shaft and steel flange was designed for maximum critical speed considering minimum static deflection and radial expansion due to bending load and centrifugal force during high speed relation. The stacking angle and the stacking thickness of the composite shaft and the adhesive bonding length of the 7teel flange were selected through vibrational analysis considering static and thermal loads due to temperature rise.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.95-96
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.615-620
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• 1996

생산성의 향상을 위하여 공작기계의 고속가공이 필요하고 이를 위한 연구가 상당히 진행되고 있다. 단위 시간당 절삭량을 올리고 알루미늄과 같은 연질 금속의 가공을 위하여 주축을 고속화하는 것이 매우 중요하나, 각 요소간의 마찰로 인한 발열에 의해 베어링의 수명단축이나 열변형 등을 동반하여 정밀도가 떨어지게 된다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.04b
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• pp.458-461
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• 1994

최근에 상품의 국제경쟁력 강화를 위해서 생산공정 시간의 단축과전문 기능인력의 부족에 대응하는 중소로 트의 다품종 생산 합리화가 기계 제조업 전체에 확산되어 가고 있다. 본 연구에서는 연삭기용 유정압 주 축의 일반적인 형태인 전부, 후부 유정압 베어링의 장착구조 대신에 기존의 정, 동특성을 유지하면서 저가의 전부 유정압베어링과 후부 Angular Contact Ball Bearing의 복합배열 구조를 제시하고 이때의 정적, 동적 성능을 이론적으로 비교, 평가하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1989.06b
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• pp.48-59
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• 1989

최근 터어보 샤프트, 터어보 팬, 터어보 쳇트 엔진, 가스 터어빈, 공작기계의 주축, 그리고 섬유기계 섬유봉등의 회전기계류 설계에서 단위 무게당 출력의 비율을 높이기 위해서 회전속도의 고속화가 요구되고 있다. 이러한 경우 회전축계의 진동특성에 크게 영향을 미치는 감쇠특성을 부각시키기 위하여 베어링의 외부에 스퀴즈-필름 댐퍼 (Squeeze-film Damper)를 부가하고 회전축계를 유연하게 지지하여 줌으로써 진동문제를 간단히 해결하며 회전속도의 고속화를 가능하게 할 수 있다. 적합하게 설계된 스퀴즈-필름 댐퍼의 잇점은 다음과 같다. (a) 회전축의 위험속도를 작은 공진쪽으로서 통과하는 것이 가능. (b) 베어링과 지지구조물에 전달되는 하중이 감소 (c) 장기간 사용중, 마모 및 브레이드 파손에 의해 진폭이 증가된 불평형 강제진동에서도 안정된 운전이 가능 (d) 미끄럼 저어널 베어링에 지지된 회전축계의 고속회전에서 불안정한 자려진동이 나타나는 안정 한계속도를 높히는 것이 가능

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.985-988
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• 2002

The Spindle-]fearing System is very important unit for geometrical accuracy in machine tools. To improve effectively the weak point of spindle system, it is necessary that the contribution ratio of spindle core parts to static and dynamic stiffness is clarified. In this paper, static contribution ratio of core parts is calculated by overlapping static deformation of basic spindle design with one flexible parts. The dynamic contribution ratio for natural frequency and dynamic deformation at spindle end is obtained by calculating correlation between original and basic spindle deformation, by curve fitting with regressive method. It is proved the validity of estimation result is correct.