• Journal of Ocean Engineering and Technology
• /
• v.17 no.3 s.52
• /
• pp.27-32
• /
• 2003

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. The geometric inaccuracy caused by the distortion tends to preclude the introduction of automation and mechanization. Thus, additional man-hours are needed for the adjusting work in the assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method that can explicitly account for the influence of various factors on the welding distortion. In order to minimize the weld-induced residual deformation, this paper proposes the optimum welding sequence as a method for distortion control. The validity of this method has been substantiated by a number of numerical simulations and experiments.

• International Journal of Railway
• /
• v.2 no.4
• /
• pp.175-179
• /
• 2009

The welding deformation and its prediction method at the HAZ (Heat-Affected Zone) are presented in this paper. The inherent strain method is well known as analytical method to predict welding deformation of large scale welded structure. Depend on the size of welding deformation in welding joints, the fatigue life, the stress concentration factor and the manufacturing quality of welded structure are decided. Many welded joints and its manufacturing control techniques are also required to railway rolling stock and its structural parts such as railway carbody and bogie frame. Proposed methods in this paper focus on the two different the inherent strain area at HAZ. This is main idea of proposed method and it makes more reliable result of welding deformation analysis at the HAZ.

• Journal of Ocean Engineering and Technology
• /
• v.23 no.2
• /
• pp.87-91
• /
• 2009

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. The geometric inaccuracy caused by welding distortion tends to preclude the introduction of automation and mechanization and requires additional man-hours for adjustment work during the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method that can explicitly account for the influence of various factors on the welding distortion. The validity of this prediction method must also be clarified through experiments. For the purpose of reducing the weld-induced bending deflection, this paper proposes the plastic counter-deforming method (PCDM), which uses line heating as the optimum distortion control method. The validity of this method was substantiated by a number of numerical simulations and actual measurements.

• Journal of the Society of Naval Architects of Korea
• /
• v.43 no.1 s.145
• /
• pp.68-74
• /
• 2006

The welding distortion of a hull structure in the shipbuilding industry is inevitable at each assembly stage. This geometric inaccuracy caused by the welding distortion tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding distortion. The validity of the prediction method must be also clarified through experiments. For the purpose of reducing the weld-induced bending deflection, this paper proposes the mechanical tensioning method (MTM) as the optimum distortion control method. The validity of this method has been substantiated by a number of numerical simulations and actual measurements.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.9
• /
• pp.63-70
• /
• 2022

Laser welding has attracted great attention as a tool used to join electrical steel coils. In this study, laser butt welding for electrical steel coil joining was conducted using the Taguchi method. It was found that structural defects such as void sand cracks were not produced in welds. This indicated that the performance of laser welding in electrical steel was excellent. According to the Taguchi analysis, the total welding quality index (TWQI) considering the bead height and roughness and tensile strength of the weld joint was almost evenly affected by laser power, welding speed, and focal position. The optimum welding conditions to maximize the TWQI were a laser power of 1220W, welding speed of 90 mm/s, and a focal position of 1mm. The regress model predicting the TWQI was also developed using the surface response method. We found that the model predicts measured values with an average error of 16.36%.

• Journal of Welding and Joining
• /
• v.27 no.3
• /
• pp.60-66
• /
• 2009

The structures distorted by welding have to be corrected. Since the correcting work needs a lot of costs and time, it is very important to minimize the buckling distortion due to welding of thin plate structure. Therefore the aim of this study is to investigate the effect of single bead on plate welding and fillet welding on the buckling distortion. In the single bead on plate welding, it was found that the welding speed and welding sequence were the most dominant factors on distortion. In the fillet welding, there were four typical buckling modes observed, and the welding sequence was the most influential factor on the buckling distortion. However typical distortion measuring method is not considered for the distortion correcting process costs of each buckling modes, therefore, in this study, the measuring method is developed to classify the buckling modes for torsion of specimen and buckling distortion depend on nodal point for the bead on plate welding specimen and fillet welds.

• Transactions of Materials Processing
• /
• v.27 no.1
• /
• pp.37-47
• /
• 2018

In this paper, a double spot welding process, utilizing electric resistance heating dies, is suggested for the spot welding of dissimilar metal plates for drawing and concurrent spot welding. This double welding process has two heating methods for the fusion welding at the interfacial zone between steel and aluminum plates, such as heating method by thermal conduction of electric resistance by welding current induced to heating dies, and heating method by electric resistance between contacted surfaces of two plates by welding current induced to copper electrode. This double welding process has welding variables such as each current induced in heating dies and in copper electrode, outer diameters of heating dies, and edge shape of copper electrode. Experiments for current conditions in welding process should be demanded in order to get successful welding strength. It was known that the welding strength could be reached to the value demanded on industry fields under such welding conditions as heating dies of outer ring dia.12mm contacted on steel plate, as heating dies of outer ring dia. 14mm contacted on aluminum plate, and as copper electrode of dia. 6.0mm, and as 3 times continuous heating method by $1^{st}$ current of 11 kA(9cycle), $2^{nd}$ current 11 kA(60cycle), $3^{rd}$ current 7 kA(60cycle) applied in steel heating dies and copper electrodes, flat edge of copper electrode, for double spot welding process of dissimilar metal plates of steel and aluminum of 1.0 mm thickness.

• Proceedings of the KWS Conference
• /
• 2000.10a
• /
• pp.40-42
• /
• 2000

This paper presents a new method of segmenting a one-dimensional signal into a set of features of type(line, Vee-groove, Lap-joint and etc.), A set of requirements for the segmentation process result from the application area, which in this case are laser welding, GMAW(Gas Metal Arc Welding), SAW(Submerged Arc Welding) and high speed tack welding. The algorithm is able to detect an exact welding position in the presence of noise and missing data, yet is reasonably economical to implement

• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.1
• /
• pp.21-34
• /
• 1999

We consider a scheduling problem arising in a shipyard subassembly welding process. There are four welding robots of gantry type, which perform the welding process for the subassemblies. Because the robots perform the welding operations at the same time, there is a possibility of collision between adjacent robots depending on the welding schedule. In this paper, we propose a heuristic method to find a welding schedule which does minimize the welding completion time while avoiding collision among the robots. The method consists of two phases: assignment and scheduling. In the assignment phase, we assign each welding line to a proper robot. In the scheduling phase, we determine the welding schedules for the robots so that collision is avoided. Computational experiences with the data which reflect the real situation are reported.

• Journal of Welding and Joining
• /
• v.10 no.4
• /
• pp.250-258
• /
• 1992

In order to clarify the mechanical behavior of welding crack and to evaluate the mechanical characteristics of welded parts in thick plate, it is very important to accurately predict the welding deformation and residual stress including transient state before welding. In this paper, the theory of a three-dimensional elasto-plastic problem for the analysis of mechanical phenomenon of welding joint on the plate is developed into an efficient and accurate method based on the finite element method, and then several examples are considered by using the proposed model. The results of numerical analyses are discussed in the viewpoint of the mechanical characteristics of the distribution of three-dimensional welding residual stresses, plastic strains and their production mechanism on the thick plate.