• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.434-437
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• 2004

This paper presents the development of a new climbing mechanism for inter-block welding in Shipbuilding. The climbing mechanism is that it is career type of robot that can pass over block interval for welding of interblock in shipbuilding. The point part of mechanism is that move ballscrew. The Ballscrew`s capacity account and dynamic analysis of leg part are achieved through this paper. Force and torque analysis were achieved by simulation. This can have strong point in side of cost-cutting and welding amount of work than existent method.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.506-511
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• 2001

Weld overlay has been developed to improve the property of material surface which is used in the severe environment. Weld overlay is the process which uses an arc heat and welds different composition of alloy on the substrate for the improvements of heat resistance and wear resistance. Weld overlay has a lot of advantages which are high hardness, good processing efficiency, easy controlling of layer thickness, good quality and low cost. In this study, weld overlay was performed by MAG welding on the base metal(SS400) with filler metal which contain composite powders(Cr+C+Mn+Mo+NbC) and solid wire(JIS-YGW11). Characterization of hardness and wear resistance were analyzed by EDS, EPMA, XRD and observations of microstructure were performed to investigate characteristics of overlays. The experimental results of overlaid specimens manufactured with Cr+C+Mn+Mo+NbC powders were obtained as fellows. ${\alpha}-phase$, M(Fe, Cr)3C and NbC of overlays were increased with decreasing the wire feed rates and increasing powder feed rates. Also the hardness of overlays were increased and the specific wear were decreased.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.292-294
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• 2006

Many processes have been introduced to join PE pipes, but most of these methods have lots of disadvantages such as costs and lack of reliability, etc. Recently due to the benefits of cost, safety and reliability, the butt welding has been paid much attention to joint PE pipes. In case of butt welding, the heat plate which is used to melt PE pipes is the most critical equipment. In this study, after developing the heat plate of new shape, the PE double wall pipes with misalignments were butt-welded by using the conventional and developed heat plates and comparison of weld-zones and tensile test was performed. As the results of tensile test, weld-zones using developed heat plate have strength of $147.7{\sim}251.0%$ of weld-zones using conventional heat plate.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.49-52
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• 1999

Tailored-welded blanks are used for forming of automobile structural and skin components. Its main objective is to achieve weight and production cost reduction in manufacturing of the components. For successful application of tailored-welded blanks design of initial welded blanks and prediction of welding line movement are critical. Here the utilization of the backward tracing scheme of the finite element method shows to be desirable in design of initial welded blanks for net-shape production and in prediction of the welding line movement. First the design of initial blank in forming of welded thick sheet with isotropy is tried and it appears successful in obtaining a net-shape stamping product. Based in the first approach the backward tracing scheme is applied to anisotropic tailored blank. The welding line movement is also discussed.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.538-543
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• 2002

M/S TB(Mash Seam Tailored Blank) is a production method for blanks by welding together blanks of different material, thickness and coating, and is an attractive method for manufacturing car body because it makes parts lighter and can save the cost and time to manufacture. However, there have not been quantified criteria to evaluate the quality of TB weld. This study introduced FHR (failure height ratio) in order to assess formability or/and weldability of the M/S welds and the applicability of FHR was confirmed by actual auto body forming and FLD tests. Furthermore, a new parameter, HN(heat number) based on the heat input of "$Q=I^2Rt$" was proposed and assessed. It was found that the concept of HN could be utilized to evaluate the soundness of M/S welds without any destructive tests.ive tests.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.227-230
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• 2009

The aim of this study was to improve extrudability limit, eliminate welding line and obtain optimum thixoextrusion conditions for manufacturing tubes of 7075 Al wrought alloy. By thixoextrusion, it was possible to improve deformability, control isotropy with extrusion direction, eliminate welding line (seamless) and save cost due to low energy consumption compared with conventional extrusion processes. The welded part was not observed at the welding line area. The grains of thixoextruded tube were homogeneously distributed and equiaxed grains were observed. Therefore, thixoextrusion is the most effective variable for the control of the magnitude of the welding line.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.420-423
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• 1995

The electric arc welding machine with high-frequency inverter is studied in this paper which could make more saving in energy than conventional ones with inherent low efficiency. The inverter circuit has been already adopted to special welding machines such as MIG and TIG for improving operating performances so much. But this adoption has not be applied to conventional ac arc welding machine until now. The proposed technology for higher efficiency is to apply the high frequency inverter, together with noise-cut transformer. Overall output characteristics are investigated in aspect of cost and circuit performance. The proposed system is conducted practical experiments using PWM controller.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.553-571
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• 2019

Geometric variation including welding distortion accumulates as many parts are joined together, ultimately affecting the final product. This variation is then subjected to correction, which requires considerable effort, time, and cost. This variation can be categorized as in-plane/out-of-plane variation. To date, studies on variation simulation have largely focused on the out-of-plane variation, however the variation generated in the in-plane direction requires more time and efforts to correct afterwards. This research aims to construct a variation simulation model considering both the in-plane and out-of-plane variations. A geometric analysis was performed to derive an equation that reflects the coupling effect of the out-of-plane variation on the in-plane variation. The proposed model is validated with case study analysis and the results shows that good fidelity in predicting and diagnosing the in-plane variation during the block assembly process considering welding distortion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3184-3190
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• 2013

These days, the great part of design processes in the field of ship or offshore manufacturing are planed and implemented using the customized CAD system for each ship-building companies. It means that all information for design and production could be extracted and reused at the useful other area cost considerable time and efforts. The representative example is the estimation of welding length and material amount which is demanded during the construction of ship or offshore structures. The proper estimation of welding material to be used and the usage of them at the stage of schedule planning is mostly important to achieve the seamless process of production and expect the costing in advance. This study is related to the calculation of welding length and needed material amount at the stage of design complete utilizing the CAD system. The calculated amount are classified according to welding position, stage, block, bevel and welding type. Moreover it is possible to predict the working time for welding operation and could be used efficiently for the cost management using the results of this research.

• Journal of Welding and Joining
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• v.13 no.1
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• pp.127-137
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• 1995

The possibility of new GMAW process using economic shielding gases including CO$_{2}$ gas was investigated on the effect of shielding gas on weldabilty. In the optimum welding condition using 600A power source, FCAW process showed low depositions rate, 114 g/min at 300A, but new GMAW using other mixed shielding gases exhibited high deposition rate, 208-224 g/min at 450A. TIME gas, Ar+CO$_{2}$ gas and Ar+CO$_{2}$+O$_{2}$ gas as a shielding gas were able to be used to the very high welding current(450A), moreover TIME gas and Ar+CO$_{2}$ gas showed the highest arc stability among shielding gases studied in this experiments. The weld penetration was performed by axial spray transfer mode of weld droplet. On the basis of workability, weldability and economic point of view, Ar mixture (80%Ar+20%CO$_{2}$) gas was recommended as a shielding gas for the development and application of new GMAW process. This shielding gas showed the low spatter, good weld quality, stable arc and low cost at the region of high welding current.