• 한국정밀공학회지
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• 제19권12호
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• pp.57-63
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• 2002

In this paper, the feedforward control with least mean square (LMS) adaptive algorithm is proposed and examined to reduce rotating error by runout of an active magnetic bearing system. Using eddy-current type gap sensor fur control, the electrical runout caused by non-uniform material properties of sensor target produces rotational error amplified in feedback control loop, so this runout should be eliminated to increase rotating accuracy. The adaptive feedforward controller is designed and examined its tracking and stability performances numerically with established frequency response function. The tested grinding spindle system is manufactured with a 5.5 ㎾ internal motor and 5-axis active magnetic bearing system including 5 eddy current gap sensors which have approximately 15 ~ 30 ${\mu}{\textrm}{m}$ of electrical runout. According to the experimental analysis, the error signal in radial bearings is reduced to less than 5 ${\mu}{\textrm}{m}$ when it is rotating up to 50,000 rpm due to applying the feedforward control for first order harmonic frequency, and vibration of the spindle base is also reduced about same frequency.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.472-477
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• 2003

Spindle state monitoring is getting more and more important according to the technology trend of spindle that is accurate and automated. Spindle state monitoring is to measure the state of rotation vibrations. The spindle rotation error motion detected by sensing device includes rotation object's unbalance, external forced vibrations, shape error of spindle, as well as measuring error of monitoring device. In this paper, we have inspected the runout characteristics. Also, we introduce the way to exclude the runout element that appear while you monitor a spindle state.

• 한국공작기계학회논문집
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• 제14권6호
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• pp.37-44
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• 2005

This paper presents fabrication techniques of the optical fiber position sensor (or spindle state monitoring. These include selection of components such as optical fibers, a laser-diode, a photo-diode, and op-amp IC of the signal process circuit. We also describe electric runout problem. The fabricated sensor has a linearity of $1.7\%$ FSO in the air gap range $0.1\~0.6mm$, a resolution of $0.37{\mu}m$ and a bandwidth of 6.3kHz. Finally, we have successfully operated a magnetic bearing spindle system using the sensors.

• Journal of Advanced Marine Engineering and Technology
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• 제36권2호
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• pp.276-285
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• 2012

본 연구목적은 열간압연용 런-아웃 테이블 롤러 표면의 기계적 성질을 개선하기 위해 다공질 자용성 합금으로 피복하는 방법을 개발하는 것이다. 열간압연에서 런-아웃 테이블의 롤러 내구성을 높이기 위해서는 고온에서 롤러표면의 경도를 높게 유지해야 하고, 내마모성, 내식성, 내열성, 내소부성 및 내응착성의 향상을 유지하여야 한다. 또한, 고온의 열연 강판을 안정적으로 이송할 수 있도록 하기 위해서는 롤러표면에 적절한 마찰계수를 유지하도록 하여야 하고, 롤러와 강판 사이에 미끄럼 발생이 없어야 한다. 본 연구에서는 자용성 합금에 텅스텐카바이드를 첨가시켜 서메트화하여 롤러의 내마모성을 증대시켰고, 미세 철분말을 롤러표면에 피복하여 다공질을 만들어 마찰계수를 높이고 붙잡음성을 향상시켰다. 그 결과, Ni-Cr 피복 롤러에 비하여 다공질 자용성 합금 피복 롤러는 피복층에 철분이 5 ~ 10 wt%로 많이 함유되어 재용융 공정에서 전기로로 가열하여 일부분만 합금화되고 나머지는 산화 및 용해에 의해 탈락되어 다공질로 나타나 강판과의 붙잡음성을 향상시켰다.