• Journal of Welding and Joining
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• 제28권3호
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• pp.42-48
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• 2010

Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) were welded by a combination of a diode laser and a CNC machining center. Laser beam delivered through the transparent PC and was absorbed in an opaque ABS. Polymers were melted and joined by absorbed and conducted heat. Experiments were carried out by varying working distance from 44mm to 50mm for the focus spot diameter control, laser input power from 10W to 25W, and scanning speed from 100 to 400mm/min. The weld bead and cross-section were analyzed for weld quality, and tensile results were presented through the joint force measurement. With focus distance at 48mm, laser power with 20W, and welding speed at 300mm/min, experimental results showed the best welding quality which bead size was measured to be 3.75mm. The shear strength at the given condition was $22.8N/mm^2$. Considering tensile strength of ABS is $43N/mm^2$, shear strength was sufficient to hold two materials. A single process was possible in a CNC machining system, surface processing, hole machining and welding. As a result, the process cycle time was reduced to 25%. Compared to a typical process, specimens were fabricated in a single process, with high precision.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.679-682
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• 2002

Resistance spot welding using air gun has been used for joining the sheet metal in automotive manufacturing process. Although air gun has many advantages, it also has the limitation to control the pressure as a factor to improve weld quality. In this study, we apply servo gun using servo motor to resistance spot welding and find the relationship between welding pressure and welding quality. Trough the experiment to change welding pressure during the welding cycle, we can make it clear that the change of welding pressure is greatly influence on the welding quality. To get in a. using response surface methodology, drew out the optimal welding pressure profile for welding quality progresses. We made an optimal profile of welding pressure which improves welding quality using response surface methodology.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.453-458
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• 2016

머신비전은 고속화된 자동화 생산 시스템의 품질 검사 방법으로 널리 활용되어 왔다. 본 연구에서는 멀티카메라를 사용하여 PC와 PLC 간 제어를 통해 용접부위의 치수를 실시간으로 측정하여 검사하는 머신비전 시스템을 개발하였다. 제안한 검사시스템은 맞대기 용접부위의 길이와 폭을 측정하여 용접부의 치수 균일성을 검사하도록 설계하였다. 광학계 및 물류는 병렬제어를 위해 PC와 PLC 간 TCP/IP 멀티쓰레딩 통신기법을 적용하였다. 금속재료의 반사 특성을 고려하여 용접비드의 형태나 용접시 발생하는 그을음에도 균일하게 검사부위의 영상획득이 가능한 동축조명계를 적용하였고, 검사 알고리즘은 OpenCV 라이브러리를 사용하여 용접치수검사에 맞게 개발하였다. 제작한 시스템을 실제 전자부품의 용접 자동화 라인에 설치하여 시스템의 작동오류 및 검사 성능을 검증한 결과, 요구되는 기능 및 검사 성능을 모두 성공적으로 수행하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.792-795
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• 1996

In TIG welding of pipe, back bead size monitoring is important for weld quality assurance. Many researches have been performed on estimation of the back bead size by heat conduction analysis. However numerical conduction model based on many uncertain thermal parameters causes remarkable errors and thermomechanical phenomena in molten pool can not be considered. In this paper, filler wire feeding force in addition to weld current, wire feedrate, torch travel speed and orbital position angle is monitored to estimate back bead size in orbital TIG welding. Monitored welding process variables are fed into an artificial neural network estimator which has been trained with the monitored process variables (input patterns) and actual back bead size (output patterns). Experimental verification of the proposed estimation method was performed. The predicted results are in a good agreement with the actual back bead shape. The results are quite promising in that estimation of invisible back bead shape can be achieved by analyzing the welding parameters without any conventional NDT of welds.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.201-206
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• 2003

Plastic injection mould have two kinds of trouble, one is in mould another in injection parts. Most of defects of the former take the cause in a design like in structure and working, the later weld line, transforming, sink mark, burning, flow mark, scratching, shading, black hole and so on. Most of problems of the later is difficult for making a clear definitely the reason of defects because of complexible. The purpose of this paper is to improve the quality of plastic injection mould and parts with inquiring the counter plan and rouble of the part of Flat TV Front Cover by flow control method and gas- assisted injection moulding. For minimizing defects from injection moulding parts, this paper was investigated with using computer aided injection mold filling simulations. Based on these numerical results, I established guidelines mould design and injection processing condition. As a results I got the improve of quality, minimizing surface defects moulded parts and troubles in mould.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1940-1944
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• 2004

• 한국강구조학회 논문집
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• 제23권4호
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• pp.483-491
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• 2011

본 연구에서는 구조용강재의 샤르피 충격시험(Charpy Impact Test)을 통해 저온에서의 충격 인성(Impact Toughness) 평가를 실시하여 사용 가능 온도를 파악함으로써 강재의 극한지 적용성을 검토하였다. 본 시험에 사용된 강재는 용접구조용강 중 현재 가장 널리 쓰이는 강종인 SM490B와 TMCP (Thermo-Mechanical Control Process)법에 의해 제조된 고강도 강재인 SM570-TMC이다. 또한, 본 시험결과와의 비교를 위해 남극 세종기지 건설시 사용실적이 있는 일반구조용강인 SS400에 대해서도 시험을 수행하였다. 대부분의 강구조물은 용접에 의해 제작되므로, 강재의 극한지 적용성 검토를 위해 용접시험판을 제작하여 모재(Base Metal), 용접금속(Weld Metal) 및 열양향부(Heat Affected Zone)에 대해서 충격시험을 실시하였다. 단, SS400의 경우에는 용접구조용강재가 아니므로 모재에 대해서 충격시험을 실시하였다. 대상 강재의 샤르피 충격시험을 통해서 저온에서의 충격흡수에너지 값을 구하고 이를 강재의 항복응력에 따른 충격흡수에너지의 기준값과 비교함으로써 강재의 사용온도를 결정하였으며, 이를 통해서 구조용강재의 극한지 적용성을 검토하였다.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.246-254
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• 2016

초대형 유류 저장탱크의 후판 용접은 작업자가 직접 손용접을 수행하는데 이로 인해 제품의 품질이 저하되고 재용접율 증가로 인하여 품질 불균일이 발생하며 작업 외부환경 등에 따른 용접 제약성도 많이 따른다. 따라서 본 연구에서는 이러한 문제점을 개선하고 용접의 신뢰도를 높이며 공사기간 단축 및 원가절감으로 생산성을 향상시키고자 자동으로 수직 용접이 가능한 용접 캐리지 시스템을 개발하였다. 수직 용접 캐리지 시스템은 용접 플랫폼 시스템, 용접 캐리지 구동장치 및 제어장치 등으로 구성되고 도출된 설계 사양이 만족되도록 개념설계가 이루어졌으며 각각의 서브시스템은 모듈로서 설계되어지고 제작, 조립되었다. 개발된 시스템에 대해 구조적 안정성 평가와 사전 문제점을 파악하고자 구조강도 해석을 수행하여 구조적 안정성을 확인하였고 그 결과를 설계에 반영하고자 하였다. 또한 개발된 시제품의 성능평가를 위해 수직 용접된 후판에 대한 인장시험, 굽힘시험, 충격시험 및 용접시간 등을 요구조건 및 수동용접과 비교 평가를 수행하였고 만족스러운 결과를 획득할 수 있었다. 특히, 수직 용접시간은 수동용접과 비교한 결과 87%이상 향상되었음을 확인할 수 있었다.

• 대한기계학회논문집
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• 제7권3호
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• pp.263-269
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• 1983

Underwater welding by a gravity arc welding process was investigated by using six types of coated electrodes and SM41A steel plates of 10 mm thickness as base metal and it was ascertained that this process may be put to practical use. Main results obtained are summarized as follows: 1. Angle of electrode affects no influence on bead appearance and the proper range of welding current and diameter of electrode for the high titanium oxide type is relatively wider than that for the ilmenite type. And the lime titania type, high titanium oxide type and ilmenite type of domestic coated arc welding electrodes of .phi.4 mm could attain the soundest underwater welded joints which contain no welding imperfection. 2. According to macro-structure, micro-structure and hardness distribution inspectionson underwater welded joint, the area between the HAZ and the surface of the weld in neighbourhood of the bond has the maximum hardness value. The structure of these parts is martensite and bainite. Other parts contain mocro-ferrite, micro-pearlite structure, which contain soundness of welded joint free from weld imperfection. 3. On consideration of both tensile strength of more than 100% joint efficiency and sufficient impact value, the welding condition which can get optimal welding strength is heat input of 1,400-1,500 J/mm, current of 200-215 ampere (voltage of 32-33 volts) in the case of lime titania type electrode. 4. Underwater welding strength (tensile strength, impact strength) depends on heat input (or current) quantitatively and they have the relationship of parabolic function. Each experimental equation has a high reliability and its percent of mean error is 4.14%. 5. It is suggested that the optimal design of weld strength by welding condition (current, heat input) could be utilized for a quality control of underwater welding.

• Journal of Welding and Joining
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• 제28권5호
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• pp.69-74
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• 2010

Irradiation behavior of the reactor pressure vessel SA508 class 3 steel weld metals was examined by Charpy V Notch impact specimens. The specimens were exposed to a fluence of $2.8{\times}1019$ neutrons(n)/$cm^2$(E>1 MeV) at $288^{\circ}C$. The irradiation damage of weld metal was evaluated by comparison between unirradiated and irradiated specimens in terms of absorbed energy and lateral expansion. The specimens for neutron irradiation were welded by submerged arc welding process at a heat input of 3.2 kJ/mm which showed good toughness in terms of weld microstructure, absorbed energy and lateral expansion. The post-irradiation Charpy V notch 41J and 68J transition temperature elevation were $65^{\circ}C$ and $70^{\circ}C$, respectively. This elevation was accompanied by a 20% reduction in Charpy V notch upper shelf energy level. The lateral expansion at 0.9mm irradiated Charpy specimens showed temperature elevation of $65^{\circ}C$ and was greatly decreased due to radiation damage.