• Journal of Welding and Joining
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• 제19권6호
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• pp.664-670
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• 2001

The HDM(Hole Drilling Method) is a relatively simple and accurate methods in measuring residual stress of weldment. Various method of evaluating residual stress are studied in welding field. The method of cutting holes on the plate much affects the accuracy of result. Especially for the hard material like stainless which is difficult to cut preciously is difficult to measure residual stress of weldment. Because heat conduction of strainless steel is lower than other general steel, the magnitude of residual stress might be different as to changing of welding conditions. Therefore, the distribution of residual stress on the STS304 steel after welding using HDM is evaluated in this paper.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.132-135
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• 2006

Injection molding is a flexible production technique for the manufacturing of polymer products, but introduces residual stresses. Residual stresses in a structural material or component are those stresses which exist in the object without other external loads. The layer removal and hole drilling method are used for the measurement of residual stress in injection molded polystyrene part. The hole drilling method is potentially more flexible for determining residual stress in complex geometries and can be used as an adoptable technique for the measurement of residual stress in polymeric materials. Results obtained by experiments agree with each other.

• 대한기계학회논문집A
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• 제37권7호
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• pp.857-864
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• 2013

레이저 정밀 가공은 고품질의 집속 광에너지를 이용하여 재료를 미세하게 가공하는 특수 가공으로 정밀 제조 분야에 적용되고 있다. 그러나 레이저 가공 시 열적 효과로 인해 재료 특성을 저하 시킬 수 있다. 또한, 압연 강재 및 강판의 경우 공정 단계에서 강한 압력으로 제작하기 때문에 반드시 잔류응력이 존재한다. 하지만 압연 강재에 존재하는 잔류응력의 양은 정량적인 예측이 불가능하다. 이러한 잔류응력이 존재하는 재료의 레이저 가공 시 레이저에 의한 부가적인 응력 발생 및 재료에 미치는 열적 영향의 예측 및 평가는 정밀 가공에 있어서 반드시 고려해야 하는 사항이다. 본 연구에서는 레이저 홀 가공 시 발생되는 온도 및 응력을 유한요소 해석과 실험적 방법으로 분석하였다. 재료의 열응력을 예측하기 위해 레이저 홀가공 실험을 수행하여 가열 및 냉각 등의 대한 결과를 도출하였다. 또한 냉각 시간에 따른 응력의 변화를 파악하였고 유한요소 해석으로 예측된 응력을 홀드릴링 응력 측정 기법에 의해 도출된 응력과 비교 검증하였다.

• 대한기계학회논문집
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• 제14권5호
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• pp.1147-1154
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• 1990

본 연구에서는 초음파 화학 가공(ultrasonicassisted chemical mahining)을 이용하여 100$\mu\textrm{m}$이하의 전극봉을 제작하였고 제작한 전극을 이용하여 미세구멍을 방전 가공함으로써 가공특성을 파악하고, 방전액을 각각 등유(kerosene)와 물로하여 구멍의 표면을 비교, 분석하였으며 전극의 지름, 가공물의 두께에 대한 오버컷과 경사도(tap- er) 그리고 전극의 마멸을 조사하였다.

• 한국기계가공학회지
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• 제12권6호
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• pp.132-141
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• 2013

Robotic Drilling Systems(RDSs) set the standard for the factory automation systems in aerospace manufacturing. With the benefits of cost effective drilling and predictive maintenance, RDSs can provide greater flexibility in the manufacturing process. The system can be easily adopted to manage very complex and time-consuming processes, such as automated fastening hole drilling processes of large aircraft sections, where it would be difficult accomplished by workers following teaching or conventional guided methods. However, in order to build an RDS based on a CAD model, the precise calibration of the Tool Center Point(TCP) must be performed in order to define the relationships between the fastening-hole target and the End Effector(EEF). Based on the kinematics principle, the robot manipulator requires a new method to correct the 3D errors between the CAD model of the reference coordinate system and the actual measurements. The system can be called as a successful system if following conditions can be met; a. seamless integration of the industrial robot controller and the IO Level communication, b. performing pre-defined drilling procedures automatically. This study focuses on implementing a new technology called iGPS into the fastening-hole-drilling process, which is a critical process in aircraft manufacturing. The proposed system exhibits better than 100-micron 3D accuracy under the predefined working space. Based on the proposed EEF fastening-hole machining process, the corresponding processes and programs are developed, and its feasibility is studied.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.89-92
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• 2001

In this paper, we studied on drilling a microscopic hole of glass using electro-chemical discharge methode. In this research, we fabricated a electro-chemical discharge machine for drilling glass hole. The used parameters to get a fine microscopic hole are the concentration of NaOH solution from 5wt% to 50wt%, the supply voltage from 10V to 40V and the fabricating time from 5 second to 50 second. Also, we used a 0.16mm glass plate. We learned from our experiment that, the fabrication most efficient when supply voltage is 25V-30V and concentration of NaOH solution 35wt% or less.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.89-92
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• 2001

In this paper, we studied on drilling a microscopic hole of glass using electro-chemical discharge methode. In this research, we fabricated a electro-chemical discharge machine for drilling glass hole. The used parameters to get a fine microscopic hole are the concentration of NaOH solution from 5wt% to 50wt%, the supply voltage from 10V to 40V and the fabricating time from 5 second to 50 second. Also, we used a 0.16mm glass plate. We learned from our experiment that, the fabrication most efficient when supply voltage is 25V-30V and concentration of NaOH solution 35wt% or less.

• Journal of Welding and Joining
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• 제31권2호
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• pp.43-48
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• 2013

This paper Investigated the characteristics of residual stress in weld is composed of typical specimens, are investigated by using three dimensional thermal elasto-plastic FEM analysis. Numerically calculated residual stresses in the gas welds were then compared with experimental results obtained by the hole-drilling method. Using the stress amplitude (${\sigma}a$)R at the hot spot point of gas weld, the relations obtained as the fatigue test results for typical specimens having various dimensions and shapes were systematically rearranged to obtain the (${\sigma}a$)R-Nf relationship. It was found that more systematic and accurate evaluation of the fatigue strength of plug- and ring-type gas-welded joints can be achieved by using (${\sigma}a$)R.

• 한국강구조학회 논문집
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• 제18권5호
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• pp.625-631
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• 2006

구조재의 잔류응력(residual stress)은 외부에서 하중이 작용하지 않는 상태에서도 구조물 내부에 존재하는 응력으로 건설현장에서 구조물을 설치, 조립하는 경우에 발생하게 되며 특히 용접이나 과부하에 의한 구조물의 설치 후에도 발생할 수 있다. 이에 본 연구에서는 600MPa급 mega structure용 강관제작 상의 프레스 및 용접에 의한 잔류응력의 영향을 파악하고자 홀드릴링 변형게이지법(Hole-Drilling Strain Gage Method)을 이용하여 용접선 부근을 중심으로 총 59개소를 측정하여 잔류응력의 분포 및 크기를 평가하였다.

• 한국생산제조학회지
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• 제9권6호
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• pp.103-110
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• 2000

Experimental study of drilling for duralumin A2024 was conducted with intermittently accelerated and decelerated feedrate. It is achieved through a programmed periodic increase and decrease in the feedrate using a machining center. The following experimental results were performed with the objective of solving chip to disposal problems. In conventional drilling of aluminum, long continuous chips are produced with winding around the drill and causing difficulties in eliminating chips from the cutting zone. In order to acquire the basic data necessary to regulate the chip profile, the relationship between cutting variables and chip shape was investigate. The following conclusions are established from the experimental results. At a suitable feed fluctuation ratio, intermittently decelerated feed drilling proved successful in braking chips to appropriate lengths while maintaining stable cutting. Thus, it is an effective method for improving chip disposal. The amplitude of the dynamic component of cutting force in intermittent feed drilling is influenced by the feed fluctuation ratio.