• Journal of Welding and Joining
• /
• v.14 no.3
• /
• pp.12-19
• /
• 1996

Spot 용접의 역사는 1877년에 E. Thomson이 발명한 것이지만 1886년 처음으로 저항 용접기의 특허를 취득할 때까지는 거의 실용화 되지 못하였다. 그 후 Thomson의 전기 용접기 회사가 저항 용접의 특허를 거의 독점한 관계로 커다란 발전없이 spot 용접에 관한 특허 분쟁이 해소된 1920년 이후 보급되기 시작하여 1935년경 부터 증가 하였다. 초기에는 주로 맞대기 용접에 이용되고 전선의 접합이나 크게는 rail의 용접 에까지 이르렀다. 금세기에 들어와서부터 spot 용접이나 seam 용접이 실용화되고 관련 용접 장치도 개발되었다. Spot 용접은 자동차 공업과 더불어 크게 발전하였으며 오늘 날에는 spot 용접 생산의 약 2/3를 자동차 공업이 점유하고 있다. Spot 용접은 고온 압접의 일종으로 각종 압접 방법중에서 가장 많이 사용되고 있는 것이다. 접합하고저 하는 부분에 직접 고전류를 통하고 그 전류에 의한 저항 발열로 용접부의 온도를 상승 시켜 용접하는 것으로서 극히 짧은 시간에 용접이 가능하고 고속, 고능률이므로 특히 다량 생산에 적합하다.

• Proceedings of the KSR Conference
• /
• 2009.05b
• /
• pp.559-564
• /
• 2009

Aluminum extrude is increasing to vehicle body manufacture of a recent railroad vehicle. Conventional welding of this aluminum extrude has been used MIG welding or resistance spot welding mainly. But the advanced manufactures like Japan's tried to apply the friction stir welding and friction spot joining at railroad vehicle body manufacture process. Therefore in this paper we tried to study to apply friction stir welding to AL 6005-T6 extrude which has been manufactured the railroad vehicle mainly. In this study we investigated first the mechanisms to affect the welding strength in friction stir welding. After we made the 3 tools of different shape, we observed how the welding strength changed while changing the welding time and the rotation speed, the plunging depth.

• Journal of Welding and Joining
• /
• v.21 no.5
• /
• pp.513-517
• /
• 2003

Resistance welding processes are widely used in automotive applications. In particular, Mash-Seam resistance welding is typically used in Tailored Blank process. If spot welds are changed to a continuous weld, it's easy to reduce noise and to be more stable in cars. A arc welding, laser welding, seam welding using wheel electrode are available to make continuous welds on a car body, but they demand operator with advanced skills and expensive cost to develop. Therefore, flat electrode continuous mash-seam resistance welding process has been used to improve the weak points in currently available system in lap seam welding. This developed process has much more strength and air tightability, and also has much better plastic workability than laser welding. Moreover, commercial RSW machine can be readily used in this welding process.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.3 s.174
• /
• pp.743-751
• /
• 2000

Because welding residual stress is formidable result in electric resistance spot welding process, and it detrimentally affect to fatigue crack initiation and growth at nugget edge of spot welded la p joints, it should be considered in fatigue analysis. Thus, accurate prediction of residual stress is very important. In this study, nonlinear finite element analysis on welding residual stress generated in process of the spot welding was conducted, and their results were compared with experimental data measured by X-ray diffraction method. By using their results, the maximum principal stress considered welding residual stress at nugget edge of the spot welded lap joint subjected to tension-shear load was calculated by superposition method. And, the $\Delta$P- $N_f$ relations obtained through fatigue, tests on the IB-type spot welded lap joints was systematically rearranged with the maximum principal stress considered welding residual stress. From the results, it was found th2at fatigue strength of the IB-type spot welded lap joints could be systematically and more reasonably rearranged by the maximum principal stress($\sigma$1max-res considered welding residual stress at nugget edge of the spot welding point.

• Proceedings of the KWS Conference
• /
• 2003.11a
• /
• pp.159-161
• /
• 2003

Electrode movement signal has been widely used in resistance spot welding system This study is to compare accelerometer signal with gap sensor signal in servo gun system. This study propose that accelerometer output signal is a useful technique of quality monitoring in resistance welding processes.

• Proceedings of the KWS Conference
• /
• 2005.06a
• /
• pp.135-137
• /
• 2005

• Journal of Welding and Joining
• /
• v.31 no.1
• /
• pp.43-50
• /
• 2013

The spot welds of Transformation Induced Plasticity (TRIP) steels are prone to interfacial failure and narrow welding current range. Hard microstructures in weld metal and heat affected zone arenormally considered as one of the main reason to accelerate the interfacial failure mode. There fore, detailed observation of weld microstructure for TRIP steels should be made to ensure better weld quality. However, it is difficult to characterize the microstructure, which has similar color, size, and shape using the optical or electron microscopy. The atomic force microscope (AFM) can help to analyze microstructure by using different energy levels for different surface roughness. In this study, the microstructures of resistance spot welds for AHSS are analyzed by using AFM with measuring the differences in average surface roughness. It has been possible to identify the different phases and their topographic characteristics and to study their morphology using atomic force microscopy in resistance spot weld TRIP steels. The systematic topographic study for each region of weldments confirmed the presence of different microstructures with height of 350nm for martensite, 250nm for bainite, and 150nm for ferrite, respectively.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.239-242
• /
• 2009

Friction stir spot welding (FSSW), developed based on principle of friction stir welding, has been paid attention as a new solid-state spot welding process. Since FSSW can produce high-quality weld in Al alloys more easily than resistance spot welding, this process has been already used for construction of Al components in the automotive industries. Despite the large industrial interests in FSSW, fundamental knowledge on welding phenomena of this process has not been fully understood. In this study, FSSW phenomena, such as the consolidation mechanism, the microstructural evolution and the material flow, were examined in Al alloy 6061. This study clarified that the elliptical zone found in the vicinity of the pin hole on the cross section was characterized by the initially lapped surface of two sheets. Moreover, the following material flow was proposed; capture of the upper material with the threads on the pin surface, spiral flow along the tool rotation, and then release at the tip of the pin.

• Proceedings of the KWS Conference
• /
• 2008.05a
• /
• pp.49-49
• /
• 2008

• Journal of Welding and Joining
• /
• v.28 no.4
• /
• pp.81-86
• /
• 2010

In resistance spot welding, regardless of the optimal condition, bad weld quality was still produced due to complicated manufacturing processes such as electrode wear, misalignment between the electrode and workpiece, poor part fit-up, and etc.. Therefore, the goal of this study was to measure the process signal which contains weld quality information, and to develop the process fault monitoring system. Welding force signal obtained through variety experimental conditions was analyzed and divided into three categories: good, shunt, and poor fit-up group. And then a monitoring algorithm made up of an artificial neural network that could estimate the process fault of each different category based on pattern was developed.