• 한국정밀공학회지
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• 제15권11호
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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.

• 한국정밀공학회지
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• 제9권3호
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• pp.149-156
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• 1992

A method for designing high speed spindle is presented in order to enhance the machining accuracy in consideration of vibration characteristics. Experimetal evaluations of the spindle HS 430 as a prototype are made efficiently with the help of bending vibration modes for nonrotational and rotationalstate comparing with the commercial spindle V430. As a result the spindle of HS 430 shows the superior performance than that of V 430.

• 소음진동
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• 제5권4호
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• pp.483-492
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• 1995

For evaluation of rotational accuracy performance of high speed machine tool spindle system, the characteristics of main spindle and tool motion behavior are presented by means of three point accuracy testing method. The results of experiments and analyses are as follows: (1) The high speed spindle rotational accuracy can be evaluated by the combination of the spindle and tool motion behavior. (2) The spindle motion behavior increases up to more that 4 times the tool motion behavior. (3) For the influence of oil viscosity on spindle and tool taper application, 32 cSt of oil viscosity showed the most satisfactory result for rotational accuracy. (4) In order to improve the rotational accuracy of high speed machine tool spindle system, it is needed to reduce the combination error. This can be achieved by improving the working accuracy and supplying the proper lubrication with contact area at the spindle and tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.505-509
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• 2001

When the spindle is rotated for machining the workpiece, the vibration is generated due to the spindle unbalance. This vibration affects surface finish, dimensional accuracy, tool life, and spindle bearings. To compensate this effect of the spindle unbalance, the spindle system using an EME(electro magnetic exciter)is proposed in this paper. In the proposed spindle system, the vibration due to the spindle unbalance is monitored using vibration sensors and is compensated by electromagnetic attractive forces generated in the EME which are excited by anti-direction forces corresponded with the measured unbalance. Firstly, the spindle system using an EME and control system are constructed to compensate the effect of spindle unbalance in this paper. And then the system is modeled by bond graph to analyze the system. Finally, a controller for vibration compensation due to spindle unbalance is designed and is implemented in real experimental system. As a result, experimental results show this proposed spindle system is very effective to compensate the spindle unbalance.

• 한국정밀공학회지
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• 제28권4호
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• pp.404-409
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• 2011

Report on the notion of uncertainty is important. The reason is that the measured value includes a lot of uncertain factors. Reliable results can't be derived without the notion of uncertainty. The mathematical model to evaluate uncertainty considering the quality of vibration is important to evaluate uncertainty, and it must contain the every quantity which contributes significantly to uncertainty in the measured results. In this paper, the evaluation of uncertainty analysis about rotor vibration measurements of machine tools is presented to evaluate the most important factors of uncertainty.

• 한국정밀공학회지
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• 제10권3호
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• pp.191-197
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• 1993

In this paper, experimental studies are mainly carried out for the evaluation of precision cutting performance of a machine tool spincle running at high speed with the low load, in consideration of the bending vibration characteristics. As a result a process in presented for the practical application in the machine tools industry to evaluate the cutting performance in design stage of spindles.

• 대한기계학회논문집A
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• 제24권7호
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• pp.1681-1688
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• 2000

A dynamic model for the prediction of surface topography in high speed end milling process is developed. In this model the effect of tool runout, tool deflection and spindle vibration were taken in to account. An equivalent diameter of end mill is obtained by finite element method and tool deflection experiment. A modal parameter of machine tool is extracted by using frequency response function. The tool deflection, spindle vibration chip thickness and cutting force were calculated in dynamic cutting condition. The tooth pass is calculated at the current angular position for each point of contact between the tool and the workpiece. The new dynamic model for surface predition are compared with several investigated model. It is shown that new dynamic model is more effective to predict surface topography than other suggested models. In high speed end milling, the tool vibration has more effect on surface topography than the tool deflection.

• 대한화학회지
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• 제28권1호
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• pp.26-33
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• 1984

HF와 DF 혼합계내에서 일어나는 다음 두 진동-진동 에너지 이동 반응의 속도상수$(k_{vv})$를 n=2~5에 대해 300~800K 온도 범위에서 이론적으로 계산하였다. HF(v=n) + DF(v=0) ${\to}$ HF(v=n-l) + DF(v=l) + ${\Delta}E$(a) DF(v=n) + HF(v=0) ${\to}$ DF(v=n-l) + HF(v=l) + ${\Delta}E$(b) 이용한 충돌모형은 수소결합에너지를 분자간 상호작용의 주축으로 삼는 loosely-held, non-rigid dimer model이었고, 계산법으로는 반고전적 방법을 사용하였다. 계산 결과 반응(a)에 대한 속도상수가 반응(b)에 대한 속도상수 보다 훨씬 HF-DF 혼합계 내에서는 진동에너지가 HF에서 DF로 이동함이, 또한 반응(a)에 대한 속도 상수는 온도가 높아질 수록 감소하고, 진동 양자수가 커질 수록 증가하는 반면에, 반응 (b)에 대한 속도 상수는 온도 의존성과 양자수 의존성에 있어서 대체로 이와 반대의 경향을 보임을 밝혔으며, 이 계산 결과는 주로 에너지 차 ${\Delta}E$의 부호와 크기로써 설명될 수 있음을 보였다.

• 한국소음진동공학회논문집
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• 제19권3호
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• pp.261-267
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• 2009

The spindle with a built-in motor can be used to simplify the structure of machine tool system, while the rotor has unbalance mass inevitably. Therefore, it is important to recognize the effect of unbalance mass. This paper presents analysis of dynamic behavior of a high speed spindle with a built-in motor. The spindle is supported by the angular contact ball bearings and the rotor is fixed at the middle of spindle. The spindle used in CNC automatic lathe has been investigated using combined methodologies of finite elements and transfer matrices. The Houbolt method is used for the integration of the system equations and the dynamic behavior of spindle is obtained considering unbalance mass of rotor. Results show that increasing rotational speed of spindle magnifies the whirl responses of spindle seriously. Also the whirl responses of spindle are affected by the other factors such as unbalance mass and bearing stiffness.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2003년도 동계 학술대회 논문집
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• pp.244-250
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• 2003

국내에 보급된 방제기는 인력분무기, 동력 분무기, 동력 살분무기, 스피드 스프레이어, 붐방제기 등이 있다. 그 중 동력경운기에 탑재하거나 트랙터에 견인되는 동력분무기를 주축으로 기계화되어 있다. 작은 입경의 분무입자로서 가급적 적정량을 균일하게 뿌릴 때 방제효율을 높일 수 있는데도 불구하고, 동력분무기에 의한 액제 살포는 원거리 살포에 따라 분무입자의 입경 분포가 다양하며 대부분 분무입자가 매우 크므로 고른 살포를 기대하기 어렵기 때문에 약액을 1000대 1로 희석하여 흠뻑 적실 정도로 다량 살포를 하여 살포효율을 높이고 있다. 그러나 이러한 방제 방법은 효율성, 작업능률과 환경의 오염 측면에서 상당한 문제로 지적되고 있다. (중략)