• Journal of Welding and Joining
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• v.35 no.2
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• pp.30-34
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• 2017

The trend of the plasma cutting and laser cutting technology of metal alloys including high strength steel, aluminum alloys for the welding structures has been studied. The high-precision plasma systems offer a denser, higher energy arc that in effect produces a sharper cutting tool and high quality cutting products. The high-quality fiber laser systems with compact design and easy set-up make it ideal for cutting in the pipeline or steel structre manufacturing. This paper covers the scientometric analysis of the high efficient cutting technology which are based on the published research works in the 'plasma and laser', and 'cutting technology' obtained from Web of Science, and deals with the details of the background data of the plasma cutting and laser cutting technology.

• Corrosion Science and Technology
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• v.9 no.3
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• pp.122-128
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• 2010

The corrosion of the flexible tube in the automobile exhaust system is caused by the ambient water and chloride ions. Since welding is one of the key processes for the flexible tube manufacturing, it is required to select a proper welding method to prevent the flexible tube corrosion and to increase its lifetime. There are many studies about the efficiency of the welding method, but no systematic study is performed for the effect of welding method on the corrosion property of the austenitic stainless weldment. The aim of the present study is to provide information on the effect of two different welding methods of TIGW (tungsten inert gas welding) and PAW (plasma arc welding) on the corrosion property of austenitic stainless steel weldment. Materials used in this study were two types of the commercial austenitic stainless steel, STS321 and XM15J1, which were used for flexible tube material for the automotive exhaust system. Microstructure was observed by using optical microscopy (OM) and scanning electron microscopy (SEM). To evaluate the corrosion behavior, potentiodynamic and potentiostatic tests were performed. The chemical state of the passive film was analyzed in terms of XPS depth profile. Metallurgical analysis show that the ferrite content in fusion zone of both STS321 and XM15J1 is higher when welded by PAW than by TIGW. The potentiodynamic and potentiostatic test results show that both STS321 and XM15J1 have higher transpassive potential and lower passive current density when welded by PAW than by TIGW. XPS analysis indicates that the stable $Cr_2O_3$ layer at the outermost layer of the passive film is formed when welded by PAW. The result recommends that PAW is more desirable than TIGW to secure corrosion resistance of the flex tube which is usually made of austenitic stainless steel.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.79-83
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• 2004

The curved blocks which compose the bow and stem of a ship contain many skewed joints that are inclined horizontally and vertically. Most of these joints have a large fitness error and are continuously changing their form and are not easily accessible. The welding position and parameter values should be appropriately set in correspondence to the shape and the inclination of the joints. The welding parameters such as current, voltage, travel speed, and melting rate, are related to each other and their values must be in a specific limited range for the sound welding. These correlations and the ranges are dependent up on the kind and size of wire, shielding gas, joint shape and fitness. To determine these relationships, extensive welding experiments were performed. The experimental data were processed using several information processing technologies. The regression method was used to determine the relationship between current voltage, and deposition rate. When a joint is inclined, the weld bead should be confined to a the limited size, inorder to avoid undercut as well as overlap due to flowing down of molten metal by gravity. The dependency of the limited weld size which is defined as the critical deposited area on various factors such as the horizontally and vertically inclined angle of the joint, skewed angle of the joint, up or down welding direction and weaving was investigated through a number of welding experiments. On the basis of this result, an ANN system was developed to estimate the critical deposited area. The ANN system consists of a 4 layer structure and uses an error back propagation learning algorithm. The estimated values of the ANN were validated using experimental values.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.944-951
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• 2009

In this paper, we use image processing algorithms to detect the defects existed on a welding area automatically. It is difficult to detect the welding defects because it is sensitive to lights and has irregular patterns. For this reason, images are captured with 2 kinds of illumination condition, and are processed by 2 different algorithms for each image. The first algorithm separates some ROI's from the captured image and compares the similarity of intensity between each divided region. The second algorithm extracts boundary information from the processed image by the first algorithm, and calculates the length of boundary, curvature and base line area based on boundary information. The proposed method showed high performance in detection and classification of defects.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.298-303
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• 1997

Over the last few year, there has been a growing interest in quantitative representation of heat transfer phenomena in weld pools in order to relate the processing conditions to the quality of the weldment produced and to use this information for the optimisation and robotization of the welding process. Normally, a theoretical model offers a powerful alternative to check out the physical concepts of the welding process and to calculate the effects of varying any of parameters. To solve this problem, a transient 2D(two-dimensional) heat conduction were developed for determining bead geometry and temperature distribution for the GMA welding process. The equation was solved using a general thermofluid-mechanics computer program, PHOENICS code, which is based on the SIMPLE algorithm. The simulation results showed that the calculated bead geometry from the developed models reasonablely agree with the experiment results.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.73-81
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• 2003

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. Original metal flow of condenser tube by porthole die extrusion is similar to hollow cylinder extrusion but the estimation of metal flow for extrusion parameters is different. For example, variation of chamber length in hollow extrusion only affects the welding pressure, however, the welding chamber length in condenser tube extrusion influences to the welding pressure as well as the deflection of mandrel. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to angular variation in the bottom of chamber in porthole die. Estimation was carried out using finite element method in as non-steady state. Analytical results can provide useful information the optimal design of porthole die.

• Transactions of Materials Processing
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• v.12 no.3
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• pp.214-220
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• 2003

In the case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. There have been few studies about condenser tube extruded by porthole die. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to variation of chamber length in porthole die. The welding chamber height in condenser tube was calculated by using finite element method. Forming analysis results for condenser tube would provide useful information for the optimal design of porthole die.

• Journal of Welding and Joining
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• v.18 no.4
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• pp.48-54
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• 2000

Adaptive control in the robotic GMA(Gas Metal Arc) welding is employed to monitor information about weld characteristics and process parameters as well; as t modify those parameters to hold weld. The objectives of this paper are to realize the mapping characteristics of bead width through the neural network and multiple regression method as well as to select the most accurate model in order to control the weld quality(bead width0. The experimental results show that the proposed neural network estimator can predict bead width with reasonable accuracy, and guarantee the uniform weld quality.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.323-327
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• 1996

Gap and thickness difference information between blanks are often necessary for tailored blank welding quality evaluation , optimum welding parameters selection and evaluation of shearing machine, blink allocation device accuracy and clamping device. We develope 3D vision system and camera unit using structured lighting for this purpose. A simple ar d efficient scheme for gap and thickness feature recognition Is developed as well as measurements. Experimental results shows this system measuring accuracy is 10 ${\mu}{\textrm}{m}$ and 16${\mu}{\textrm}{m}$ for gap and thickness difference respectively The data are expexed to be useful for preview gap control.

• Journal of Welding and Joining
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• v.17 no.2
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• pp.97-103
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• 1999

The dynamic resistance monitoring in primary circuit is one of the important issues. Because in-process and real time quality assurance of resistance spot weld is needed to increase the product reliability. In this study, new dynamic resistance detecting method is proposed as a practical manner of weld quality assurance using instantaneous current and voltage measured at the primary circuit. and also, various patterns of primary dynamic resistance curve are characterized with the macro photograph and the weldability lobe curve. It is found that the primary dynamic resistance patterns are basically similar to those of the secondary, but there is evident advantage such as no extra devices are needed to obtain the quality information and eventually real time feedback control will be possible.