• Laser Solutions
• /
• v.5 no.1
• /
• pp.33-42
• /
• 2002

In order to investigate the characteristics of the plasma induced by lap-joint CO$_2$ laser welding of automotive steel sheets, the effects of welding speed, shield gas flow rate, gap size, and laser beam defocus to plasma intensity emitted from keyhole have been investigated. The plasma light is measured by fiber and photodiode. Also, the plasma images were captured by the high speed digital camera in 1000frames/sec in order to correlate the plasma light signal with plasma pattern. From the results, it is observed that the difference of the plasma intensity for between the deep penetration and partial penetration exists from 1.2 to 2 times. The plasma light intensity decreased in case of the deep penetration Is observed due to the exhausting of the plasma gas under the sheet. On the other hand, under the conditions of the deep penetration, the plasma intensity is significantly increased by controling the conditions decreasing the penetration depth. It was specially founded that the effect of 0.3mm gap size at partial penetration condition is approximately similar to deep penetration in 0mm gap. It is concluded that the plasma intensity is able to evaluate the penetration depth in lap-joint welding and appears to offer the most straightforward correlation to the welding process.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2006.09a
• /
• pp.122-127
• /
• 2006

In case of lap joint fillet welds of thin plate, the example which is applicable to Plasma Welding increases substituting for the exiting TIG Welding but the quality of Plasma arc welding has a special feature influenced sensitively by the condition of welding caused by controlling the various parts of welding torch. This research is purposed to improve lap joint fillet welds of thin plate in high quality and attain the high productivity and it is examined that how the change of electrode tip angle and Setback has an effect on the quality of welding and it is investigated how the change of Setback and Standoff has an effect on Melting efficiency using Response Surface Analysis.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.3
• /
• pp.66-72
• /
• 2010

Recently, the use of means of transportation of the lightweight aluminum to temper the trend is increasing. More efficient use of lightweight aluminum material to Friction stir welding has been widely attempted. Types of welding tools at the right screw to rotate anti-clockwise direction, when the tensile stress exerted on the location of the top plate to the left in the direction of the welding process to the installation was able to obtain high tensile strength. A5052 to the top of the left in the direction of the welding process to install and, when you installed the right under the A6061 was not easily come up to the top of the A5052. Conversely, at the bottom left to install on top of the A6061 and A5052 have been installed at the bottom of the upper area of the A6061 and A5052 intrude easily form the shape of the hill you can see that it was formed.

• Journal of Welding and Joining
• /
• v.20 no.4
• /
• pp.510-516
• /
• 2002

Recently the laser welding technology has been applied increasingly for the automotive bodies. But the lap joint laser welding for 3 dimensional automotive body is new while the butt joint laser welding is well known as the tailored blank technology. In this study, the process window was found for the full penetration welding of the lap joint of the 1mm-thick high strength steel sheets. The limit curves and characteristic curves were suggested to define the boundaries and the contour lines in a space of the welding speed and the gap size. The characteristics of the weld sectional geometry were used to determine the limit curves. They are bead width, penetration depth and sectional area. After the observed data was analysed carefully, it was noticed that there was a transition point at which the sectional shape was changed and the bead area jumped as the welding speed was increased. Also a new concept of 'input energy Per volume' was suggested to distinguish the difference at the transition Point. The difference of sectional areas at the transition point can be related to the dynamic keyhole phenomena.

• Journal of Welding and Joining
• /
• v.29 no.3
• /
• pp.82-88
• /
• 2011

With a tendency for the application of thin magnesium alloy plates in portable electronic equipment such as cell phone and notebook PC, there is a requirement to develop a welding technology for the lap welding of these thin magnesium alloy. This paper presents the single pulsed laser welding of AZ31B magnesium alloy. The effects of fiber types and parameters such as peak power and pulse width on laser weldability were investigated. The results show that weld defects, especially solidification crack, were always generated in the weld. These defects couldn't be controlled by the simple square pulse, but could be improved through the application of variable pulse. It is because that variable pulse has effect of solidification delay by dropping peak power gradually.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.67-67
• /
• 2010

최근 전 세계적으로 유가상승 및 환경에 대한 관심이 증대되면서 자동차 업계에서는 차량 경량화를 통한 연비향상에 대한 연구가 활발히 진행되고 있다. 대표적인 차량 경량화 방법으로 초경량 철강 차체의 개발을 들 수 있는데 이는 고강도강을 차체에 적용함으로써 강성을 증대시킴과 동시에 두께 감소에 의한 경량화를 이루는 방법이다. 하지만 고강도강은 자체의 높은 강성을 지니는 반면 첨가된 합금원소에 의하여 용접성이 떨어지는 제약을 가지고 있다. 펄스 GMA 용접은 One Drop Per Pulse (ODPP) 의 안정된 용적 이행으로 스패터 발생이 거의 없으며 일반 GMA 용접에 비하여 용접성이 우수하여 자동차 차체 조립공정에 적용되고 있다. 본 연구에서는 440MPa 급 도금, 비도금 강판 및 이종 강판의 겹치기 용접 실험을 통해 강종별, 두께별 펄스 아크 용접에 대한 용접성 평가 및 데이터 베이스를 구축하고자 하였다. 용접부 단면마크로, 인장시험, 경도시험을 통해 적정 용접영역을 확보하였으머, 고속카메라 촬영을 통해 보호가스에 따른 용적 이행 현상을 확인하였다.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.29-29
• /
• 2010

레이저 용접은 고밀도 에너지빔을 이용하는 용접방법으로 아크용접에 비해 빠른 용접과 깊은 용입이 가능하며, 낮은 열이력을 가지는 장점이 있다. 때문에 열에 의해 연화되는 고강도강의 용접에 큰 이점을 가지고 있다. 차체경량화 추세와 더불어 차량에 고강도강의 적용이 늘어나고 있는데 충돌시 차량 구조를 유지시켜주는 범퍼나 B-필러와 같은 부품에 적용되는 무도금 보론 합금강과 알루미늄 코팅 보론 합금강은 핫스템핑(Hot Stamping) 기술에 의해 제조된 소재로 약 1.5GPa의 인장강도를 가진다. 알루미늄 코팅 보론 합금강의 경우 제조공정과 이송 중 소재 표면산화에 의한 산화철발생 또는 표면 탈탄 현상을 방지하기 위해 알루미늄 코팅 처리를 하는데 이러한 코팅층이 용접시 용접부의 물성을 저하시키는 역할을 한다고 보고되어 있다. 본 연구에서는 1.5GPa급 무도금 보론 합금강과 알루미늄 코팅 보론 합금강을 대상으로 레이저 용접을 적용하여 용접부 특성을 파악하고자 하였다. 실험은 겹치기 형상으로 Fiber Laser, Disk Laser를 적용하여 진행하였으며 빔Size, 용접속도, Gap등을 변경하며 해당조건에서의 용입특성, 파단모드, 기계적특성 등을 알아보았다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2000.10a
• /
• pp.171-177
• /
• 2000

It is essential to understand the creep behavior, which shows how long the characteristics of material maintains because press joined molding GMT-Sheet for recycle is usually used in the severe environment. In this study, we predict joining strength of GMT-Sheet for recycle, when lap length was changed. and we will investigate how compression ratio have an effect on creep behavior in press joined molding. The result of experiment of forming condition concerned with joining problem of GMT-Sheet is as followings joining efficiency. of GMT-Sheet, increases as lap joint length I, increases. Increase of compression ratio causes decrease o f joining efficiency after of GMT-Sheet joining. As the result of creep test, GMT-Sheet is easily damaged in high temperature range, because it is sensitive to the temperature

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.5
• /
• pp.48-55
• /
• 2002

An Internet-based software called the Repair Advisory Service (RAS) was developed to assist aircraft composite repair. The RAS takes advantage of the web user interface and provides estimation of the failure loads of repaired composite laminates and Structural Repair Manual (SRM) with search capability. In this paper, a failure model of lap repair is discussed as an example of the modules in the RAS. The model takes into account anisotropy of each ply in the laminate and in the repair ply, and non-elastic behavior of the interlayer between the laminate and the repair patch. Failure loads calculated by the model were compared with test data, and a good agreement was found between the results of the model and the test.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.553-553
• /
• 2000

The application as the parts of an automobile, using the property of GMT-Sheet, is increasing. In order to exchange the parts of an automobile for GMT-Sheet, at first, the establishment and joining problem of exact joining strength must be determined. We have studied it using composites which is not same each other fiber oriented condition so as to determine joining strength and joining condition of GMT-Sheet. h this study, the result of experiment of forming condition concerned joining problem of GMT-Sheet is this ; joining efficiency of of GMT-Sheet, increases as lap joint length L increases. Increase of compression ratio causes decrease of joining efficiency after of GMT-Sheet joining. In the viewpoint of recycling, randomly oriented composite of GMT-Sheet is desirable more than unidirectional oriented composite. We has better design the structure so as not to occur to stress centralizatien on the joining part.