• 한국정밀공학회지
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• 제28권6호
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• pp.709-715
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• 2011

Chattering in cutting operations are usually a cumbersome part of the manufacturing process in mechanical. Particular, machining performance such as that of the boring process is limited by cutting condition at the movable components. Among various sources of chatter vibration, detrimental point in cutting condition is found a mechanical condition on overhang. It limits cutting speed, depth, surface roughness and tool wear failure as result because the all properties are varying with the metal removal process. In this case, we have to observe the resonance frequencies of a boring bar for continuous cutting. In the established research, boring bar vibration of cutting system has been measured with the aid of accelerometer. However, the inherent parameters of internal turning operations are severely limit for the real time monitoring on accelerometers. At this point, this paper is proposed other method for real time monitoring during continuous cutting with optical fiber at the inside of boring bar. This method has been used a plastic fiber in the special jig on boring bar by based on experimental modal analysis. In this study, improvement of monitoring system on continuous internal cutting was attempted using optical fiber sensor of inside type because usually chattering is investigated experimentally measuring the variation in chip thickness. It is demonstrated that the optical fiber sensor is possibility to measure of chattering with real time in boring process.

• 화약ㆍ발파
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• 제34권2호
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• pp.1-9
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• 2016

본 논문에서는 PLHBM의 환산 거리별 공수에 따른 터널 심발공의 진동감쇠효과를 비교하기 위해 편마암지역에서 V-cut, PLHBM 1공, PLHBM 2공에 대한 현장실험을 수행하였다. 시험결과 얻어진 발파진동추정식을 근거로 하였을 때 진동 감쇠율은 V-cut의 PPV를 기준으로 환산거리 $10{\sim}100m/kg^{1/2}$의 범위에서 PLHBM 1공 적용 시 21.8~61.1%, 2공 적용시 35.7~79.3%로 나타났다. 진동감쇠효과는 환산거리가 증가할수록 작아지는 경향을 보였으며, PLHBM 1~2공은 심발공의 진동감쇠효과가 높은 것으로 나타났다.

• 한국정밀공학회지
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• 제27권8호
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• pp.62-69
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• 2010

Internal lathe machining with a boring bar is weak with respect to vibration because the bar is long and slender. Therefore, it is important to study the dynamic characteristics of a boring bar. The purpose of this study was to identify the effects of overhang and cutting conditions on the dynamic response characteristics of a boring bar. For an efficient experiment, an $L_g(3^3)$ orthogonal array was applied and the results were quantitatively analyzed by ANOVA. Overhang, feed per revolution, and depth of cut were selected as independent variables. Meanwhile, dynamic stiffness, damping ratio, damping coefficient, and acceleration were chosen as dependent variables. The vibration signal was obtained from an accelerometer attached to the boring bar, followed by visualization by a signal analyzer. The effect of overhang was found to have a significant effect on the dynamic stiffness, damping ratio, and damping coefficient, but the other variables did not. As the length of the overhang increased, the dynamic stiffness decreased and the damping ratio increased. In addition, the damping coefficient increased until the length of the overhang was 4D (where D is the shank diameter), after which it remained constant. The acceleration decreased until the overhang length was 4D, and then increased sharply when the overhang was increased further. From these results, the behavioral trend of the damping characteristics changed when its overhang length was 4D. Consequently, there is a critical point that the dynamic characteristics of boring bar change.

• 한국지반신소재학회논문집
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• 제22권3호
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• pp.61-69
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• 2023

세계 무역 및 항만 산업 환경이 변화함에 따라 선박의 대형화 및 고속화에 대한 대응 필요성이 높아지고 있다. 이에 따라 부산, 울산 등 광역도시를 중심으로 신항만의 건설이 이루어지고 있다. 일반적으로 신항만 건설은 모래 또는 자갈을 사용한 다짐공법이 적용되고 있다. 하지만 모래 또는 자갈이 부족하고, 단가상승으로 인해 경제성 확보가 어려워 최근에는 단시간에 요구되는 압축강도를 확보할 수 있는 심층혼합공법이 사용되고 있다. 따라서 본 연구에서는 순환자원을 이용한 CMD-SOIL을 울산지역에 적용하고, 실내 배합시험 및 현장 확인 보링 결과를 분석하여 적용성을 판단하고자 하였다. 시험결과, CMD-SOIL은 설계 배합강도 이상을 나타내었고, 고로슬래그 시멘트와 유사한 성능을 확보할 수 있는 것으로 분석되었다. 또한 현장에서의 확인 보링 결과, 설계 기준강도 이상을 충분히 확보할 수 있어 울산지역에서의 현장 적용성을 고려할 때 CMD-SOIL의 활용이 가능할 것으로 판단된다.

• 한국기계가공학회지
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• 제10권4호
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• pp.82-87
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• 2011

Lubrication has an important role to reduce frictional forces and temperature between cutting chips and the face of a tool. However, it has harmful effects to workers' health and working environment. The purpose of this thesis is to find cutting conditions through the quality analysis in boring for SM45C steel using MQL(Minimum Quantity Lubrication). Machining process is super drill, tip drill, end mill and boring in order. Experimental factors of boring and the quantity of mist air are properly selected. With the analysis of experimental data, this thesis shows that boring with MQL improves the surface roughness when spindle speed is 934rpm or feeding speed is 74mm/min.

• 한국생산제조학회지
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• 제20권4호
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• pp.495-501
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• 2011

The purpose of this study is to improve the roundness of CNC turning so that helps the operator to choose the right turning conditions to produce a product with the given parameters. This paper focuses on determining the optimal levels of machining factors for circular shaft with CNC turning. For this purpose, the optimization of factors is performed based on experimental design method. A design and analysis of experiments are conducted to study the effects of these factors on the roundness by using the SIN ratio, analysis of ANOVA, and F-test. Factors, namely, fixed pressure, wall thickness, depth of cut, and feed rate are optimized with consideration of the roundness. The boring tool used in this study is a tungsten carbide coated. The material of workpiece is Al6061 and the machining method is dry cutting.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2004년도 하계학술대회
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• pp.215-218
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• 2004

통신서비스를 제공하는 전송매체인 동케이블(copper cable)은 외륵 전자기적 영향으로부터 작업자 및 시설보호를 위해 $300{\sim}500m$ 마다 접지를 하고 있다. 접지는 일반 보안용 접지와 차폐용 접지로 구분할 수 있는데 보안용 접지는 100옴 이하의 접지저항을 요구하지만 차폐용 접지는 10옴 이하의 낮은 접지저항을 필요로 한다. 차폐용 접지는 대표적으로 전력선 또는 전철시설로부터 발생하는 통신선에서의 유도전압(Induced voltage)을 경감시키기 위해 사용되는 것으로 차폐케이블, 유도중화코일, 차폐선 등의 선로시설에 필요하다. 본 논문은 차폐용 접지를 시공하기 위해 적용하는 접지저감재를 활용한 보링접지 시공기술에 관한 것으로 접지저항 산출방법과 산출식에 필요한 파라메터와의 관계 등을 실제 시공결과와 비교하며 분석하였다.

• 한국생산제조학회지
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• 제9권3호
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• pp.143-149
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• 2000

Grinding technology in morden industry society is focusing on research and development for grinding stone and machin-ing parts for the purpose of high accuracy and high efficiency of products. But in order to equip the high technology and high accuracy of micro stone which is one of grinding stone a continuous effort on R& D is require. In this study the honing processing work of 2 cycle engine cylinder for motorcycle which has an open hole is carried out so as to investigate the boring and hone stone effects on accuracy of honing. As the experimental result of this study we could conclude that it is possible to secure good conditions of honing by controlling and keeping appropriate cycle-time in the stage of boring for the prior step of honing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1796-1802
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• 2000

The purpose of this work is to analyze the vibration characteristic of boring bar with dynamic vibration absorber and find out the effective design parameters. Using the finite element method and modified optimum design concept, conventional optimum design based on approximate lumped parameter model is checked and practical design to be measured with modal analysis is compared with optimum design from numerical analysis. Also, the performance of reducing vibration is investigated with variation of shape of boring bar. The considered model of boring bar with dynamic vibration absorber is selected among manufactured boring bars with the best performance.

• 한국지반공학회논문집
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• 제16권2호
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• pp.13-22
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• 2000

서해안에 위치한 특정 연구현장에서 연약지반의 압밀거동을 파악하기 위한 소산시험을 포함한 콘관입시험을 수행했다. 연구현장에서 시험시공으로 적용한 연약지반개량공법으로는 압성토공법, 두 종류의 페이퍼드레인 공법, 팩드레인 공법이었으며 각각의 공법들에 있어 현장에서의 지반개량에 따른 압밀거동을 판정하기 위해서 적용되었다. 콘관입시험은 근본적으로 지반개량 전과 후에 보링, 표준관입시험, 압밀시험과 함께 수행되었다. 실내실험과 피조콘관입시험을 비교한 결과, 연약지반의 표층에서는 상당한 지반개량효과가 있었으나 표층아래 심층지반에서는 그렇치 않았다. 그리고 지반개량 후, 10개월이 지난 시점에 압밀시험과 소산시험 결과를 통하여 분석한 수평압밀계수는 압성토 방법을 제외한 3가지 개량공법을 적용한 지점에서 압밀계수는 감소하여 개량효과를 간접적으로 판단할 수 있었다.