• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.315-316
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• 2010

• International Journal of Precision Engineering and Manufacturing
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• 제6권1호
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• pp.51-58
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• 2005

The development of the high-efficiency machine-tools equipment and new cutting tool materials with high hardness, heat- and wear-resistance has opened the way to application of high-speed cutting process. The basic argument of using of high-speed cutting processes is the reduction of time and the respective increase of machining productivity. In this sense, the spindle units may be regarded as one of the most important units, directly affecting many parameters of high-speed machining efficiency. One of the possible types of spindle units for high-speed cutting is the air-bearing type. In this paper, we propose the mathematical model of the dynamic behavior of the air-bearing spindle. To provide the high-level of speed capacity and spindle rotation accuracy we need the adequate model of "spindle-bearings" system. This model should consider characteristics of the interactions between system components and environment. To find the working characteristics of spindle unit we should derive the equations of spindle axis movement under the affecting factors, and solve these equations together with equations which describe the behavior of lubricant layer in bearing (bearing stiffness equations). In this paper, the three influence coefficients are introduced, which describe the center of spindle mass displacement, angle of shaft rotation around the axes under the unit force application and that under the unit torque application. These coefficients are operated in the system of differential equations, which describes the spindle axis spatial movement. This system is solved by Runge-Kutta method. Obtained trajectories and amplitude-frequency characteristics were then compared to experimental ones. The analysis shows good agreement between theoretical and experimental results, which confirms that the proposed model of air-bearing spindle is correctis correct

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1005-1008
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• 1995

The spindle is a very important part of machine tool. The evaluation of spindle motion is required for improving the performance of machine tools. The evaluation tools have been developed for precison spindle by the reversal technique, and 3D error map motion of spindle is proposed. This technique makes us understand the total movement of spindle more easily. The proposed technique has been successfully applied to practical machine tools, giving high potentials for the spindle performance measurement.

• Asian-Australasian Journal of Animal Sciences
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• 제22권11호
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• pp.1477-1486
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• 2009

Female germ cell meiotic divisions are typically asymmetric, giving rise to two daughter cells with different sizes. Spindle movements including spindle migration from the oocyte center to the cortex and spindle rotation from parallel to perpendicular (typically in the mouse) at the cortex are crucial for these asymmetric divisions and therefore are crucial for gamete production. Different regulatory mechanisms for spindle movements have been determined in different species and a wide variety of different molecular components and processes that are involved in spindle movements have also been identified in different species. Here, we review the current state of knowledge as well as our understanding of mechanisms for spindle movements in different systems with focus on three main aspects: microtubules (MT), microfilaments (MF) and molecules associated with cytoskeletal organization as well as molecules that are not directly related to the cytoskeleton. How they might interact or function independently during female meiotic divisions in different species is discussed in detail.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.184-187
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• 2000

This paper describes action of synchronous error between z axis and spindle axis on rigid tapping. Because rigid tapping cuts the threads synchronizing the movement of z axis to spindle rotation, synchronous error between z axis and spindle is very important. Increase of synchronous error degrades the accuracy of thread and crushes the tap in worst case. So we developed the realtime measurement system of synchronous error in order to know the action of synchronous error on rigid tapping. In result, we have known that synchronous error was increased according to rise of spindle speed and z axis speed. And because the cutting torque(M3-30Ncm∼M10-300Ncm) on rigid tapping are less than maximum motor torque(3500Ncm), it specially doesn't affect the synchronous error. The most important parameter which has affected the increase of synchronous error was acceleration/deceleration time. On worst case, spindle motor was tripped because of the excess of synchronous error. Because the acceleration/deceleration time ocuupies the most of the total cutting time, in order to move on the high speed rigid tapping, the acceleration/deceleration time of spindle must be remarkably reduced.

• 한국정밀공학회지
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• 제13권1호
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• pp.45-52
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• 1996

It is one of the important causes that the precision of the thread grinder decide the machining errors of the ball screw. The approach described in this study demonstrates how the dominant causes of the inaccuracies in thread grinding system can be determined. To evaluate the machining error of thread grinder, rotary encoder is allocated to spindle shaft and master screw for measuring the rotational transfer error between spindle shaft and master screw and the laser measuring system is used for checking the movement error.

• The Korean Journal of Physiology
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• 제4권2호
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• pp.19-24
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• 1970

Since the discovery of the muscle spindle by Hassall (1831), an intensive studies of its anatomical and physiological characteristics had been undertaken. Recent morphological studies of Boyd (1962) demonstrated that the muscle spindles have two different intrafusal muscle fibers, nuclear bag and nuclear chain fiber, and these intrafusal fibers are under independent motor innervation by ${\gamma}_1$ and ${\gamma}_2$ motor neurone. Neurophysiological studies of Hunt and Kuffler (1951) showed regulatory effect of ${\gamma}$ motor neurone upon the excitability of the spindle afferents. Harvey and Mathews (1961) observed the dynamic and static characteristics of the two different spindle afferents, the primary and secondary ending. Furthermore, Mathews (1962) postulated the functional existance of two kind of ${\gamma}$ motor neurones, namely, the dynamic and static fusimotor fiber. Recent report of Kim and Partridge(1969) pointed out that the descending vestibular signals had increased the slope of the length-tension relationship in stretch reflex; Kim (1967) demonstrated that the descending vestibular impulses act upon the stretch reflex loop through the ${\gamma}$ motor pathway. These experimental evidences from the morphological and neurophysiological studies on the muscle spindles support the concept that the stretch reflex action of the skeletal muscle operates as a negative feedback control system. The author had discussed the way by which the f system participates in the control of stretch relfex feed back system. that was taken for a prototype of posture and movement.

• 한국기계가공학회지
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• 제4권2호
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• pp.16-23
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• 2005

This study is intended to find out the reason of interference phenomenon of a machine tool when it operates for 5-axises working. The researcher made a Virtual Machine which has same figures of the 5 axises machine tool and Virtual Manufacturing System which has both Software factors - controller and NC code data to manipulate the movement characteristics of the machine - and Hardware factors - fixtures, workpiece, tools, holders and so on. With these virtual tools, this study is designed to find out the relation between the movement and the interference or collision, and also intended to verify the simulation and work-processing. In this study, the researcher found out, in case of the vertical 5 axises type, that it has more chances to have interference between the fixture, the workpiece and the main spindle including the tool holder due to the tilting kinetics of the main spindle. In case of the horizontal 5 axises type, on the other hand, the researcher found out that it has more possibility to have the interference between the main spindle and the rotary shaft.

• 한국융합학회논문지
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• 제9권5호
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• pp.145-150
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• 2018

공작기계의 주축은 황삭 가공에서 부터 정삭가공에 이르는 다양한 작업들이 가능해야 하고, 정속운동 또는 회전 위치결정의 기능을 수행해야 되므로 주축설계에 고려해야 할 변수들이 많다. 주축이동식자동선반은 고정식자동선반에 비해 샤프트가 가늘고 긴 핀 들을 작업할 때 좋은 선반이다. 고정식 자동선반에 비해 외경가공의 밀도가 매우 높다. 주축 이송형 선반은 주로 소형 제품을 정밀가공 할 경우에 사용되므로 가공 정밀도가 높아야 한다. 최대 외경 가공 한계 치수는 Ø32, 내경가공 한계 치수는 Ø6까지 가공이 가능하게 제작되어야 한다. 본 연구에서는 주축이동식 자동선반에 사용되는 SCM440 소재의 정 동적특성을 이동식 선반에 적용하여 분석하였다. 주축의 정,동적 특성에 영향을 미치는 인자들을 고려하여 고속화 및 고정밀도를 갖는 최적설계기술이 확보하기 위하여 수치해석을 이용하여 분석하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.119-120
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• 2010