• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.537-538
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• 2013

• 한국정밀공학회지
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• 제10권2호
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• pp.95-103
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• 1993

In the manufacturing field, some traditional manufacturing and machining methods become weakened the productivity, the external competitive power, and accuracies of the products. In these point of view, the unmanned and intelligent manufacturing systems are proposed by some manufacturing companies. The real-time monitoring technology of the cutting tool conditions i.e. tool wear, tool breakage, crack, and chipping anre necessarily reauired to realize those system, especially. In this study, we constructed the multi- sensing system using the acceleration sensor, the current sensor, and the loadmeter of a machine tool. Also, we analyzed the nose breakage, the massive signal, and some monitoring features by means of the developed system.

• 한국정밀공학회지
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• 제14권11호
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• pp.93-101
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• 1997

Ever since the nonlinearity of machine tool dynamics was established, researchers attempted to make use of this fact to devise better monitoring, diagnostics and control system, which were hitherto based on linear models. Theory of chaos which explains many nonlinear phenomena comes handy for furthering the analysis using nonlinear model. In this study, measuring system will be constructed using multi-sensor (Tool Dynamometer, Acoustic Emission) in end milling process. Then, it will be verified that cutting force is low-dimensional chaos by calculating Lyapunov exponents. Fractal dimension, embedding dimension. And it will be investigated that the relation between characteristic parameter calculated from sensor signal and tool wear.

• 한국정밀공학회지
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• 제12권4호
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• pp.67-77
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• 1995

In modern industry the requirement of automation of manufacturing process increases so that unmanned system has been popular as an ultimate goal of modern manufacturing process. In unmanned manufacturing process the tool fracture is a very serious problem because it results in the damage of workpieces and can stop the operation of whole manufa- turing system. In this study, image processing technique is used to detect the fracture of insert tip of face milling using multi-point-tool. In order to acquire the image information of fracture shape of rotation insert tip. We set up the optical system using a light beam chopper. In this system we can reduce the image degradation generated from stopped image of rotating insert tip using image restoration technique. We calculated the mean square error to diagnose the condition of tool fracture, and determind the criteria of tool fracture using experimental and staticstical method. From the results of this study we've developed non- contact detection technique of tool fracture using image processing method and proposed the fracture direction of automation and unmanned system considering the optimal time of tool change milling.

• ETRI Journal
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• 제27권5호
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• pp.635-638
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• 2005

Spatial audio coding (SAC) is an extremely high compact representation of encoded multi-channel audio material. This paper suggests a multi-channel audio service in the terrestrial digital multimedia broadcasting (T-DMB) system using a novel SAC tool, which is called a virtual source location information (VSLI)-based SAC tool. Intensive experiments are presented to evaluate the validity of the proposed VSLI-based SAC tool, and prototypical systems are also presented to demonstrate the reliability of the proposed multi-channel T-DMB system in real applications.

• 한국생산제조학회지
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• 제9권5호
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• pp.119-126
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• 2000

Recently, according to the various taste of consumers, the design of a product is changed variously and complicatedly. The complicated product is not usually constructed with one path but multi-path. By the way, in machining, higher precision and the reduction of leading and machining time is required. But, for the multi-patch sculptured surface, the amount of machining data becomes large. This means the increase of leading and machining time. In this study, the tool path generation method with reparameterization is proposed for multi-patch sculptured surface and variable step size using NURBS is used to satisfy the precision and to reduce leading and machining time.

• 한국공작기계학회논문집
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• 제18권2호
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• pp.162-169
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• 2009

This paper describes a study on dynamic characteristics analysis and dynamic compliance evaluation of a 5-axis multi-tasking machine tool of ram-head type. Structural dynamics analysis and evaluation are necessary to machine tool design and development to secure good machine tool performance against tough and harsh machining conditions. In this study, natural frequencies and corresponding vibration modes of the machine tool structure were analyzed by using both F.E.M. modal analysis and impulse hammer test. Furthermore, dynamic compliance of the machine tool was analyzed by using F.E.M. and also measured by using a hydraulic exciter test. Both the theoretical analysis and experimental test results showed good agreement with each other.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.395-405
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• 2019

In the present work, the effects of cutting parameters on surface roughness parameters (Ra), tool wear parameters (VBmax), tool vibration (Vy) and material removal rate (MRR) during hard turning of AISI 4140 steel using coated carbide tool have been evaluated. The relationships between machining parameters and output variables were modeled using response surface methodology (RSM). Analysis of variance (ANOVA) was performed to quantify the effect of cutting parameters on the studied machining parameters and to check the adequacy of the mathematical model. Additionally, Multi-objective optimization based desirability function was performed to find optimal cutting parameters to minimize surface roughness, and maximize productivity. The experiments were planned as Box Behnken Design (BBD). The results show that feed rate influenced the surface roughness; the cutting speed influenced the tool wear; the feed rate influenced the tool vibration predominantly. According to the microscopic imagery, it was observed that adhesion and abrasion as the major wear mechanism.

• 한국기계가공학회지
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• 제20권2호
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• pp.38-44
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• 2021

To cater to the transition from single-color to multicolor/multi-material printing, this paper proposes a cartridge-replacing type multi-nozzle Fused Depositon Modeling(FDM) three-dimensional (3D) printer. In the test printing run, tool change failure/wobble/layer shift occurred. It was confirmed that improper support was the cause of this tool change failure. As a solution, spline and electromagnetic cartridges were designed. Wobble was caused by machine vibration and the motor stepping out. To minimize wobble, an additional Z-axis was installed, and the four-point bed leveling method was used instead of the three-point bed leveling method. The occurrence of layer shift was ascribed to the eccentricity of the Z-axis lead screw. Therefore, slit coupler was replaced with an Oldham type. In addition to the mechanical supplementation, the control environment was integrated to prevent accidents and signal errors due to wire connections. Before the final test printing run, a rectifier circuit was added to the motor to secure precise control stability. The final test printing run confirmed that the wobble/layer shift phenomenon was minimized, and the maximum error between layers was reduced to 0.05.

• 한국융합학회논문지
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• 제9권11호
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• pp.277-284
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• 2018

최근 다축 가공을 통한 정밀가공의 수요가 크게 증대되고 있다. 그러나 5축 이상의 다축 공작기계는 기하학적 관계가 복잡하여 공작기계의 기하학적 정밀도 평가와 분석이 어렵다. 본 연구에서는 먼저, 여러 가지 규정으로 분산되어 있는 KS/ISO 규격을 정리하여 다축 공작기계의 기하학적 정밀도 평가 항목을 체계화하였다. 또한, 다축 공작기계의 정밀도를 평가하고 분석하기 위해 표준공작물을 제안하였고, 표준 공작물을 사전에 정해진 방법과 절차에 따라 가공한 후, 가공면을 3차원 측정하여 분석하였다. 그 결과 표준공작물의 가공 결과와 공작기계의 정밀도가 정성적 및 정량적으로 매우 유사함을 확인하였다. 이 결과로부터 다축 공작기계의 정밀도 분석이 표준공작물의 가공만으로 가능함을 확인할 수 있었다.