• 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.

• 한국금형공학회:학술대회논문집
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• 한국금형공학회 2008년도 하계 학술대회
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• pp.27-30
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• 2008

It was investigated that two rods of aluminium can be welded by hot extru-welding method with extru-welding dies, and that the extru-welding on the welding surface were analyzed by computer simulation according to the steped shapes of welding dies. It was known by computer simulation that welding pressure on the welding section of rods welded using extru-welding dies and that the welding pressure on the welding section of rods using extru-welding dies is lowerer than the welding pressure of rods using stepped welding dies. And it was known by experiments that two rods of aluminium can be welded on the end sections by hot extru-welding method using fan-shaped stepped welding dies without relative rotational movement of contacted aluminium rods needed for the purpose of friction heating and pressure.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.173-181
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• 2000

The stability of a structural plate is a crucial problem which causes wrinkling and buckling. In this paper, the effect of the pattern of spot-welding points in the two rectangular plate on the shear buckling load is studied with respect to the thickness, the aspect ratio of plates, the number of welding spots. Buckling coefficient of the simple plate was compared with that of two plates with various conditions to extract the effect of buckling strength. The effect of the number of welding spots are studied in two directions, longitudinal and transverse directions. The concluded that the reinforcement effect was maximized when the aspect ratio was close to 1.5 and that the effect of number of welding spots in longitudinal direction was larger than that in transverse direction.

• Journal of Welding and Joining
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• 제31권3호
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• pp.4-10
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• 2013

In electronic industry, the trend of future electronics will be flexible, bendable, wearable electronics. Until now, there is few study on bonding technology and reliability of bonding joint between chip with micro solder bump and flexible substrate. In this study, we investigated joint properties of Si chip with eutectic Sn-58Bi solder bump on Cu pillar bump bonded on flexible substrate finished with ENIG by flip chip process. After flip chip bonding, we observed microstructure of bump joint by SEM and then evaluated properties of bump joint by die shear test, thermal shock test, and bending test. After thermal shock test, we observed that crack initiated between $Cu_6Sn_5IMC$ and Sn-Bi solder and then propagated within Sn-Bi solder and/or interface between IMC and solder. On the other hands, We observed that fracture propated at interface between Ni3Sn4 IMC and solder and/or in solder matrix after bending test.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.42-49
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• 2005

In general, multi-lap spot weld joints are frequently present in automobile. Most research, however, has been focused on the single-lap spot weld joints until now. In this paper, tensile-shear strength tests are performed to examine the weldability of 3-lap spot joint welded by using the high strength steel sheet and the zinc coated steel sheet. The indentation depth and nugget diameter are used to propose the optimum welding conditions. The weldability is affected by the welding current and welding time for 3-lap spot joint. Meanwhile the expulsions is round to decrease with the increase of electrode force. The optimum welding conditions are presented for 3-lap spot joints of high strength steel sheet and zinc coated steel sheet.

• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.145-152
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• 2015

The article aims to apply a friction stir spot welding for producing the lap joint between AA5052 aluminum alloy and C11000 copper alloy. The dimension of the materials was 100 mm in length, 30 mm in width and 1.0 mm in thickness. The copper plate was set overlap the aluminum plate by 30 mm. The welding parameter was the rotating speed of 2500-4000 rpm, the pin inserting rate of 2-8 mm/min and the holding time of 6 sec. The mechanical properties test and the microstructure investigation were performed to evaluate the lap joint quality. The summarized results are as follows. The friction stir spot welding could produce effectively the lap joint between AA5052 and C11000 copper. Increase of the rotating speed and holding time directly affected to decrease the tensile shear strength of the lap joint. The optimized welding parameters in this study that indicated the tensile shear strength of 864 N was the rotating speed of 3500 rpm, the pin inserting rate of 6 mm/min and the holding time of 4sec. The experimental results also showed that the hardness of the weld metal was lower than that of the base materials.

• Journal of Welding and Joining
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• 제24권1호
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• pp.71-76
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• 2006

In this study, the microstructure and mechanical properties of spot friction stir welded A 5052 alloy were investigated. Especially, the effect of insertion depth of welding tool on microstructural changes and mechanical properties was investigated in order to obtain the optimum spot friction stir welding condition. The lap shear load of spot friction stir welded A 5052 alloy plates showed lower value at the shallowest insertion depth and increased with tool insertion depth. At 1.6mm, the maximum value of 3.35 kN was obtained, and then dropped to lower load when the insertion depth was deeper. Spot friction stir welded joints showed shear fracture mode at shallower insertion depths and fracture mode changed to plug fracture mode as the insertion depth was deeper.

• Journal of Welding and Joining
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• 제34권6호
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• pp.69-74
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• 2016

Because the pure titanium has superior corrosion resistance and formability compared with different material, it is widely used as material of welded heat exchanger. When the welding of heat exchanger is carried out, certain area in which welding start and end are overlapped occurs. The humping of back bead is formed in the overlap area due to partial penetration. Thus in this study, the experiments were carried out by changing the length and wave shape of overlap area, and then the weldabiliay was evaluated through the observation of microstructure, the measurement of hardness and tensile-shear strength test in the overlap area. When overlap length was 9.8mm, humping bead was suppressed. The microstructure of overlap area coarsened and its hardness increased due to remelting. As a result of tensile-shear strength test in the overlap area according to applying the wave shape control, it was confirmed that the overlap area applied wave shape control had more excellent yield strength and ductility.

• 한국건축시공학회지
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• 제22권5호
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• pp.451-462
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• 2022

이 연구의 목적은 다양한 접합상세를 갖는 프리캐스트 콘크리트(precast concrete, 이하 PC) 전단벽에 대한 BIM 모델링 절차를 정립하는 것이다. 그 결과 스케치업(SketchUp)의 프로그램과 컴포넌트 기능과 IFC(Industry foundation classes)파일 형식을 이용하여 BIM 프로그램에서 사용가능한 PC 전단벽 패밀리 라이브래리를 구축 할 수 있었다. 스플라이스 슬리브, 볼트 또는 용접접합공법을 이용한 PC 전단벽은 BIM 프로그램으로부터 배근된 철근들의 간섭여부와 콘크리트, 철근 및 철재 재료들의 물량을 정확히 평가할 수 있었다. 평가 결과 용접접합 공법을 이용한 PC 전단벽은 판재, 볼트 및 너트를 사용하였음에도 스플라이스 슬리브로 연결된 PC 전단벽에서 사용된 재료들의 전체물량, 경제성 및 환경영향성이 비슷한 수준에 있었다. 결과적으로 볼트 또는 용접접합 공법은 PC 전단벽에서 적용가능성이 높은 공법이며, 특히 시공성까지 고려한다면 스플라이스 슬리브 공법보다도 더 유용한 연결공법이 될 것으로 판단된다.

• Journal of Welding and Joining
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• 제31권5호
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• pp.71-76
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• 2013

The effect of zirconate having - NH functional group on the T-peel and lap shear strength of $CaCO_3$ containing structural epoxy adhesive for car body assembly was investigated. Curing behavior of epoxy adhesive samples were investigated by differential scanning calorimeter (DSC) techniques. The addition of zirconate up to 7.5 phr did not affect the curing mechanism of epoxy adhesive. While the small amount of zirconate addition less than 1.1 phr increased the cross-linking density, the excess addition of zirconate resulted in the increase of uncross-linked impurity. From the increase of T-peel and lap shear strength and the change of fracture mode from the adhesive failure to the mixed one, it was considered that the small addition of zirconate was effective in improving the adhesion strength of epoxy adhesive to the adherend and inorganic filler surfaces. The formation of uncross-linked impurity with the excess addition of zirconate was considered to decrease the joint strength by decreasing the cohesive strength of the cured epoxy.