• Journal of the KSME
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• v.26 no.3
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• pp.195-199
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• 1986

지금까지의 해설과 같이, 3-조오 척의 조오- 공작물사이의 접촉상태는 가공물의 정도와 진선도 및 채터 안정성에 직접적인 영향을 주고 있다. 일반적으로 긴 접촉길이를 갖는 완전접촉상티는 선접촉이나 중심선접촉상태보다도 2∼4배 가량의 가공정도나 진원도 향상을 가져오며, 채터 안 정성에 있어서도 현저한 진전을 나타낸다. 따라서 선삭시에 클램핑 접촉상태는 가공물정도나 진원도를 해석하는 과정에서 중요한 인자로서 취급되어야 할 것이며, 구체적인 해석적 과정을 갖지 않고서 원활한 가공결과에 접근하기 위해서는 완전접촉의 상태로서 비교적 접촉 길이를 공작물 반경에 가깝도록 하는 것이 바람직하다고 볼 수 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.04a
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• pp.121-126
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• 1991

기계가공에서 발생하는 채터진도에 대한 발생기구나 이론적인 해석방법에 관하여는 많은 연구 가이루어져 왔으나, 그 발생점을 객관적으로 판정하기위한 엄밀한 규정이 마련되어 있지 않기 때문에 현재까지 공작기계의 성능평가에 하나의 지표가 되고 있는 채터진동 발생점의 판정에는 주로 인간의 귀나 눈에 의한 감각적인 판단방법에 의존하고 있는 실정이다. 본 연구에서는 객관적인 채터진동 발생점의 판정 및 그의 in-process 검출방법을 확립할 목적으로, 이를 이룩하는데 절삭저항의 이용 가능성을 실험적 인 방법으로 검토하고 있다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.706-713
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• 1985

It is clear that when the amplitude of grinding chatter increases enough the contact between grinding wheel and workpiece cannot be sustained and the loss of contact occurs during a period of grinding chatter. In this paper the behavior of nonlinear grinding chatter due to the loss of contact has been studied. A nonlinear grinding chatter loop is developed where the loss of contact is considered as a nonlinear element of asymmetrical gain. The analysis is carried out in the time domain by numerical simulation and also in the complex domain by use of describing function method. The results show that two typical patterns of nonlinear grinding chatter can originate from the nonlinearity. One is an irregular chatter frequency at starting stage decreases to the natural frequency of grinding structure while the chatter amplitude increases and decreases repeatedly. The other is a limit cycle chatter of which the amplitude and frequency converge to constant and remain. This nonlinear behavior of grinding chatter has been well analyzed by the describing function method and confirmed by the numerical simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.51-56
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• 2001

공작기계로 금속을 절삭할 때 공작기계의 불안정, 즉 자려진동의 발생은 절삭과정과 공작기계구조 두 요소의 동적 거동에 기인한다. 공작기계의 채터와 구조의 동적인 거동은 모든 금속가공에서 가공물의 표면조도와 공구수명, 공작기계의 수명에 큰 영향을 미친다. 이와 같은 채터와 동적인 거동을 해석함으로써 최적의 절삭 조건을 결정할 수 있으나, 이러한 연구에서 가장 어려운 점은 기계구조와 절삭과정이 폐회를 구성하고 있기 때문이다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.274-278
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• 2014

Machining performance is often limited by chatter vibration at the tool-workpiece interface. Chatter vibration is a type of machining self-excited vibration which originated from the variation in cutting forces and the flexibility of the machine tool structure. Cutting tooling method is one of major factor to chatter vibration in turning process. Even though lots of cutting tooling methods are developed and used in machining process, precise analysis of cutting tooling effect in view of chatter vibration behavior. This study presents numerical and experimental approaches to verify and effects of various cutting tooling geometry and clamping method on the onset of chatter vibration. Acquired knowledge from this study will apply the optimal geometry design of cutting tooling and adjusting of machining process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.3
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• pp.210-217
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• 2009

This paper presents the analytical prediction of stability lobes in milling. The stability lobes are obtained by measuring the frequency response function (FRF) of a machining center at the cutting point of the end mill cutter, identifying cutting constants, and approximating cutting force coefficients. The stability lobes are experimentally verified through cutting tests.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.126-135
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• 1989

In this study, in order to perform dynamic design of machine tools reasonably and effectively, a method was formulated to be applicable to the structures connected by joints having elasticity and damping by using substructure synthesis method. And to analyze chatter-free performance, a 3 dimensional cutting dynamics theory was used. Computer program package for the dynamic design of machine tools was developed by combining those and spplied to improvement of performance of NC lathe. Also, the optimization in the structural modifications of machine tool substructure was studied by evaluating the effects of the substructural modifications on total system performance.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.151-157
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• 1999

Vibrations in machine tools make many problems in precision, production efficiency, and machine performance. The relative vibration between a workpiece and a tool is very complicated due to many sources. In this study, the dynamic characteristics of a newly developed CNC lathe were analyzed and its chatter characteristics were predicted by a chatter analysis method using finite element analysis and 3 dimensional cutting dynamics. The simulated results showed very complex characteristics of chatter vibration and the borderline of limiting depth of cut was used as the stability limit. To check the validity of this method, cutting tests were done in the CNC lathe using a boring bar as a tool because boring process is very weak due to long overhang . The experimental results showed that the simplified borderline was to be considered as limiting depth of cut at which the chatter vibration starts and the stability limits depended on various cutting parameters such as cutting speed, feed and nose radius of tool.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.424-432
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• 1989

A mathematical model is developed for determination of the dynamic cutting force from static cutting data. The dynamic cutting force is analytically expressed by the static cutting coefficient and the dynamic cutting coefficient which can be determined from the cutting mechanics. The proposed model is verified by the chatter stability charts. A good agreement was shown between the stability limits predicted by the theory and the critical width of cut determined by experiments. The static cutting coefficient dominates high speed chatter stability, while the dynamic cutting coefficient dominates low speed chatter stability.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.4
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• pp.463-470
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• 1986

본 연구에서는 절삭공정 중 발생하는 공구의 접촉이탈 현상에 의하여 공작 물의 절삭된 표면중에 한회전 및 그 이전 회전에 절삭된 절삭면의 형상이 현재의 절삭 깊이에 영향을 미치는 다중재생효과(multiple regenerative effect)가 존재하는 선삭 작업에서 공구의 착탈현상을 고려한 비선형채터(nonlinear chatter)를 공작기계의 생 산성의 관점에서 절삭공정의 특성을 고려하여 해석하였으며, 수동제어기의 일종인 임 펙트댐퍼를 절삭공정에 응용하여 절삭작업중에 공작기계의 안정성향상 뿐만 아니라 생 산성의 증가효과를 규명하였다.아울러 댐퍼자체의 설계변수에 따른 채터 억제효과 를 고려하여 최적의 댐퍼를 설계하는 방법을 제시하였다.