• Proceedings of the KWS Conference
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• 2005.11a
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• pp.70-72
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• 2005

Nuclear fuel assemblies for pressurized water reactors(PWR) are loaded in the reactor core throughout the residence time of three to five years. A spacer grid assembly, which is an interconnected array of slotted grid straps and is welded at the intersections to form an egg crate structure, is one of the main structural components of the nuclear fuel assembly. The spacer grid assembly is structurally required to have enough buckling strength under various kinds of lateral loads acting on the nuclear fuel assembly so as to keep the nuclear fuel assembly straight. To meet this requirement, it is necessary to weld the welding parts carefully and precisely. In this study, laser welding qualities of the Zircaloy spacer grid assembly welded by two welding companies, such as weld strength, weld penetration depth, and weld bead size, are examined and compared.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.988-989
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• 2006

The ultrasonic welding is with features of high electric conductivity and hot conductivity when it is used in metallic bond, high electric conductivity and hot conductivity when it is used in various metallic bonds, excellent quality when it is used for advanced junction, easiness when it is used in various metallic bonds, being needless for the exhaustive material and being benefit for the environment. Currently the use of ultrasonic welding is increasing in the industrial fields such as the automobile battle, the refrigerator, the air conditioner, the battery and the solar cell junction. But the production ability is insufficient in our country and it is necessary to explore the core technology of the ultrasonic welding. In this paper, the output LC resonance filter and 35kHz squal wave onion occurrence Full Bridge plans was designed. The output examination of the ultrasonic oscillator and the ultrasonic welding examination were done. The method for getting more smooth result in the ultrasonic welding machine system was researched.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.2
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• pp.152-159
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• 2005

This paper describes the application of a model-based system design method critical to complex intelligent systems, PSARE, to a welding robot development to define its top level architecture. The PSARE model consists of requirement model which describes the core processes(function) of the system, enhanced requirement model which adds technology specific processes to requirement model and allocates them to architecture model, and architecture model which describes the structure and interfaces and flows of the modules of the system. This paper focuses on the detailed procedure and method rather than the detailed domain model of the welding robot. In this study, only the top level architecture of a welding robot was defined using the PSARE method. However, the method can be repeatedly applied to the lower level architecture of the robot until the process which the robot should perform can be clearly defined. The enhanced data flow diagram in this model separates technology independent processes and technology specific processes. This approach will provide a useful base not only for improvement of a class of welding robots but also for development of increasingly complex intelligent real-time systems.

• Journal of Welding and Joining
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• v.32 no.5
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• pp.32-43
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• 2014

Welding and joining technology has become a core field. Therefore it is more widely applied to nonferrous metals, inorganic and polymeric materials. That is because the high performance, high function and diversification trend of materials used as industrial technology develops. In the laser welding process, STS 304 and SCP1-S were used as the base materials, the output density was fixed $7MW/cm^2$, the protective gas was argon(Ar) and the transfer rate was fixed 5 mm/sec. and it was progressed while the magnetic field is gradually increasing by 100 mT ranging 0 to 400 mT. The tensile test showed in average about 6 % tensile strength improvement in the case of the laser welding process using the magnetic fields. In the shielded metal arc welding process using SPHC only or the combination of SPHC+STS304 as base materials. The electric current was set at 80 Amperes and the protective gas used argon(Ar) the same as the laser welding process and the strength of magnetic fields. In the shielded metal arc welding process using the magnetic fields, the tensile tests showed about 5 % tensile strength improvement in the case of using SPHC only, 3 % tensile strength improvement in the case of using the combination of SPHC+ STS304. In comparing the results of numerical analysis to the results of experimental tests, it was revealed that the temperature, thermal stress distribution and the behavior of molten pool were similar to those of real tests. Consequently, it may be considered that the numerical assumption and the analytical model used in this study were reasonable.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.94-99
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• 2019

Friction stir welding was first reported by TWI(The Welding Institute) in 1991, and this welding method has been rapidly used in various industrial areas such railway, automobile, aerospace and shipbuilding industry. Here, we study core characteristics of friction stir welding (FSW) applied to Al 6005-T6 extruded sheets, which is the typical alloy used for railway car bodies. With the fixed welding speed of 500 mm/min, the rotating tool speed was varied from 600 to 1800 RPM. The results of hardness measurement revealed that the hardness of nugget area is ~70% with respect to the parent material, and for the selected range of rotation speed, no clear dependence was observed and the hardness values close to the parent materials were achieved for the area located 5 mm away from the welding interface. The tension test shows that yield strength and tensile strength were slightly decreased with increasing RPM, with no observed difference for the elongation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.5
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• pp.329-337
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• 2016

The demand for the eco-friendly vehicles is skyrocketing because of the increasing $CO_2$ emissions and global warming. In the industrial field, the battery process, a core part of an eco-friendly vehicle, is drawing increased attention; its weight lightening as well as high energy density are becoming increasingly important. In this study, pure Ni plates that were used as the battery pole plate were welded using the laser. The lab joint welding was conducted on ten pure Ni plates at a laser power of 1900 W and a feed speed of 2.8-3.4 m/min. As observed in the experiment, a faster feed speed reduced the bead width, but the laser did not penetrate all ten specimen plates. In addition, pores were trapped when protective gas was used, but they were not trapped when the welding was conducted in atmospheric condition.

• Journal of Welding and Joining
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• v.33 no.2
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• pp.69-77
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• 2015

High strength steels have been continually being developed to improve in fuel economy in automotive and ensure safety of passengers. New bonding and welding methods have been required for improving weldability on high strength steels. In this study, resistance spot welding and Weld-bond with nugget diameters of 4.0mm, 5.0mm, 6.0mm and 7.0mm were produced and tested, respectively. In order to confirm the effect of nugget diameters on tensile shear characteristic of the Weld-bond, tensile shear characteristics of Weld-bond were compared with those of resistance spot welding and adhesive bonding. Peak load of Weld-bond were increased as the nugget diameter increases. After appearing maximum peak load continuous fracture followed with second peak owing to load being carried by resistance spot weldment. Fracture modes of the adhesive layer in Weld-bond fractures were represented by mixed fracture mode, which are cohesive failure on adhesive part and button failure at resistance spot welds. The results showed that the tensile shear properties can be improved by applying Weld-bond on TRIP steel, and more apparent with nugget diameter higher than 5${\surd}$t.

• Journal of Welding and Joining
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• v.31 no.6
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• pp.84-89
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• 2013

The demand of LNG tank and the constituting material, i.e., the Al5083 thick plate, increased due to the rapid growth LNG market. To weld the Al5083 thick plate, the gas metal arc welding (GMAW) of high current is necessary to increase manufacturing productivity incurred by the multi pass welding. However, the arc welding vaporizes the volatile element such as magnesium (Mg). This phenomenon changes the Mg composition of the weld metal and the mechanical properties. The study investigated the weldability of Al5083 alloys after conducting high current GMAW. The Al5083 alloy was welded by using different size of welding wires and high current (800-950A). As the arc current increased from 800A to 950A, the mechanical strength decreased and the secondary dendrite arm spacing (SDAS) increased. Even though the arc current increased SDAS, the mechanical strength decreased due to the Mg loss in the weldment. The large diameter of welding wire decreased the dilution of the weld, therefore increasing the Mg content and the strength of the weld. For the reason, the content of Mg in welds was a major parameter to determine the mechanical property for the high current GMAW. For the arc current between 800A and 950A, the yield strength of the weldments showed a relationship with the weight percent of Mg content ($X_{Mg}$): Y.S = 27.9($X_{Mg}$)-11.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1312-1316
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• 2007

Strip casted and rolled magnesium sheet is become exiting material for car manufacturer, due to its better formability and specific strength compare with conventional extruded sheet. TWB technology was attractive for car body designer, because it saves the weight of the car without strength loss. In this study, the laser welding performance of magnesium sheet was investigated for Mg TWB panel manufacturing. The material was strip casted and rolled magnesium alloy sheet contains 3 wt% Al and 1 wt% Zn (AZ31). Lamp pumped Nd:YAG laser of 2kW was used and its laser light was delivered by optical fiber of 0.6mm core diameter to material surface with focusing optics of 200mm focal length for TWB welding. The microstructure of weld bead was investigated to check internal defects such as inclusion, porosity and cracks. Also mechanical properties and formability were evaluated for press forming of car body. For the results, there was no crack but inclusion or porosity on weld at some conditions.The tensile strength of weld was over 95% of base metal. Inner and outer panel of engine hood were press formed and assembled at elevated temperature.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.12-18
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• 2015

The ultimate goal of developing body is revealed the "lightweight" at latest EuroCarBody conference 2012 and the most core technology is joining process to make lightweight car body design. Accordingly, in this study, the car body assembly line for the assembly process applies to any introduction, particularly in the assembly of aluminum alloy and composite materials applied by the process for the introductory approached. Process were largely classified by welding (laser, arc, resistance, and friction stir welding), bonding (epoxy bonding) and mechanical fastening (FDS, SPR, Bolting and clinching). Applications for each process issues in the case and the applicable award was presented, based on the absolute strength of the test specimens and joining characteristics for comparative analysis were summarized. Finally, through this paper, we would tried to establish the characteristics of the joint for lightweight structure.