• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.313-314
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• 2012

• 한국공작기계학회논문집
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• 제11권2호
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• pp.17-23
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• 2002

A cylindrical capacitance-type spindle displacement sensor was developed and its effectiveness as a system to monitor cutting forces during hard turning was tested in this research. The sensor was installed between the face of spindle cover and the chucking element and measured pure radial motion of the spindle under the condition with presence of roundness error at measured surface. To prove the effectiveness of the developed system hard aiming tests using ceramic inserts and tool steel as workpiece were conducted. The workpiece was hardened up to 65 Rc. The variations of pure radial motion of the spindle ware measured during the cutting tests. The signals from the sensor showed the same pattern of cutting force variations from the tool dynamometer due to the progress of tool wear. As the flank wear of the ceramic tool increased both static component of cutting forces and the amount of center shift of spindle orbit increased, Results from the research showed that the developed sensor could be utilized as an effective and cheap on-line sensing device to monitor cutting conditions and tool performance in the un-manned machining center.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.113-114
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• 2010

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.235-236
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• 2009

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.133-134
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• 2006

A cylindrical capacitive displacement sensor (CCS) was developed and applied for monitoring end milling processes. Dynamic characteristics of a spindle-assembly were measured using the CCS and a designed magnetic exciter. The technique to extract the spindle displacement component caused only by cutting from the measured signals using the CCS was proposed in the paper. Using CCS signals and FRF (Frequency Response Function) derived from dynamics of the spindle tool system, dynamic cutting forces are estimated quantitatively.

• 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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• 제16권6호
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• pp.140-145
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• 2007

To improve productivity of a metal cutting process, it is required to monitor machining stability in real time. Since cutting environment is harsh against sensing conditions due to vibration, chip, and cutting fluid, etc., it is necessary to develop a robust and reliable sensing system for the practical application. In this work, a chatter monitoring system was developed and its effectiveness was proved. Spindle displacement caused by cutting was selected as a main monitoring parameter. A cylindrical capacitive displacement sensor was adopted. Chatter frequencies were identified through modal analysis. To quantify chatter vibrations, chatter correlation coefficient was introduced. The identification of the monitoring system showed a good agreement with the result of experiment.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.131-136
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• 2003

Five expensive sensors are necessary to control a magnetic bearing system. The sensor price rate of magnetic bearing system is high. So it is necessary that cheap and good sensor is developed. The optical fiber displacement sensor is adaptive to satisfy this condition. We can design magnetically suspended spindle based on static characteristic of optical fiber displacement sensor developed. The controller can be designed by decoupled feedback PD. Therefore, it is simpler than any other controller comparatively.

• Tribology and Lubricants
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• 제24권1호
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• pp.34-43
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• 2008

In this paper, an actively controlled aerostatic bearing is studied to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled aerostatic bearing is composed of aerostatic bearings, non-contact type of displacement sensors, piezoelectric actuators and controllers. The cylindrical capacitance sensor (CCS) is used as the displacement sensor. The reason for using CCS instead of the commercial gap sensor is that it can give us the pure error motion of the spindle because it removes the roundness error or the geometric errors in the spindle. The controller is designed by the state space equation and quadratic optimal control theory. The characteristic data of the actively controlled aerostatic bearing system in the frequency domain are presented and the stiffness and damping coefficients of the bearing are mentioned. This paper shows the possibility to reduce the motion error up to 6000 rpm.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.93-98
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• 2003

High speed precision machines have been introduced to the CNC industry in order to improve productivity, shorten the appointed date of delivery and reduce the prime cost. High speed machines have more functions then general machines, and they were proved in performance. The production and sales of the high speed machines have been increased not only in domestic market but also all over the world. Accordingly, machines are faster, there are lots of problems to be solved. One of the most difficult problems is the thermal displacement on the main spindle due to generated heat while the spindle is rotated in high speed. Since the thermal displacement directly effects the quality of the machined parts, utmost efforts to minimize the thermal displacement have to be given from the beginning of designing machines. In practice, variety of methods are attempted and practiced to minimize the thermal displacement such as design of symmetrical frame, adoption of high speed bearings, application of compensation system using non-contact sensor and use of forced circulating lubrication system with oil cooler. Even if these variable methods have been practically used in the industrial field, generated heat has not been Perfectly Prevented lienee, in this paper, the characteristics of thermal displacement were investigated when several kinds of oil were tested for a high speed machine with forced circulating lubrication system within the same atmosphere and under the same conditions.