• 한국생산제조학회지
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• 제20권1호
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• pp.74-80
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• 2011

In this study, a variety of welding experiments were carried out to optimize root-pass welding process using GMA process. Based on the experimental results, optimal welding conditions were selected after analyzing correlation between welding parameters and back-bead geometry. Then, effectiveness of empirical models developed was compared and analyzed, and optimized empirical models were finally developed for predicting back-bead by analyzing the main effect of each factor which affects back-bead geometry and their influence on interaction. Also, functions proper for expressing the surface of back-bead were selected using diverse quadratic functions, and back-bead geometry was visualized using empirical models developed and quadratic functions.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.729-733
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• 1997

Due to the variety of disturbance, it is not ease to accomplish the in-process detection of weld line with non-contact sensor. To get around this difficulties problem develop an automatic seam tracking weld system, the reliable signal processing algorithm has been recommanded. In this research, laser displacement sensor is applied as a seam finder in the automatic tracking system. The sensor is controlled by a dc servo motor which is mounted at X-Y moving table. X-Y moving table manipulated by an ac servo motor controls the position and velocity of the welding torch. First, X-Y table moves to Y-axis to search the welding joint feature before starting the welding, and welding joint is from the scanning data and weighting factor for each other. Second, weld line is determined using proposed signal processing algorithm during welding process. Form the experimental results, we could see the possibility that laser displacement sensor with procesed algorithm can be used as a seam finder in welding process under the severe noise (spatter,arc light etc.) condition

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1996년도 특별강연 및 춘계학술발표 개요집
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• pp.13-14
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• 1996

High Frequency Electric Resistance Welding process has been widely used in manufacturing welded steel pipes because of its high welding speed and quality. This process utilizes the skin effect as well as the proximity effect of the high frequency current in heating the skelp edge. In this study, an analytical solution of the edge temperature was obtained based on several assumptions. The assumptions includes the expontial decay of weldingcurrent from the surface and neglect of the heat loss in the welding direction. This calculation shows a good agreement with the observations made from the high speed camera. Using tile analytical model, tile heat required as a function of the welding speed and the skelp thickness was determined. These results were compared with the experimental results obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.301-302
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• 2006

In this paper, the possibilities of the Infra-red sensor in sensing and control of the bead geometry in the automated welding process are presented. Infra-red sensor is a well-known method to deal with the problems with a high degree of fuzziness so that the sensor is employed to build the relationship between process variables and the quality characteristic the proposed above respectively. Based on several neural networks, the mathematical models are derived from extensive experiments with different welding parameters and complex geometrical features. The developed system enables to select the optimal welding parameters and control the desired weld dimensions during arc welding process.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.138-140
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• 2005

Plasma arc welding(PAW) technology is a proven process that has already been adopted by other industrial fields and recently has been considered to join the tank structure of LNG carrier. The purpose of this study is to introduce PAW process for the root welding of stainless steel pipes instead of TIG welding. There are distinctive features of the PAW compared to TIG welding; higher energy density that can increase welding speed by more than twofold, and longer arc length that can be controlled to trace seam line easily because of allowable gap between workpiece and torch. However, PAW process is also very sensitive to the root gap and misalignment due to the characteristics of long and narrow arc shape. So, we have done various experiments to establish the allowable fit-up condition by changing welding parameters including arc length, with or without filler metal, groove shape, and obtained satisfactory result.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.53-56
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• 2007

Magnesium sheet used in electrical device due to mobility and EMF shielding characteristics. Magnesium case by press forming was advantageous compare with conventional die casting process, because of its thin gauge of wall and surface quality. But it need to makes the boss to fix inner part or assemble the case. CD stud welding was effective way for joining the boss to the thin gauge case of the electrical devices. In this study, we investigated the performances of the magnesium boss welder To measure the process parameters such as the force and the weld current, we design the monitoring system for CD stud welding. We test the characteristics of CD stud welding for AZ31 sheets at some variables. Finally we select the optimum welding range of magnesium sheets in CD stud welding process.

• 한국정보통신학회논문지
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• 제4권4호
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• pp.885-893
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• 2000

The use of neural-fuzzy system to model mesh seam welding is described in this paper. Conventional, automated process generally involves sophisticated sensing and control techniques applied to various processing parameters. Welding parameters affecting quality include the arc voltage, the welding current, torch travel speed and the pressure and so on. The relationship between the welding parameters and weld quality is not a direct one, and in addition, the effect of the weld parameter variables are not independent of the each other. The effectiveness of the proposed neuro-fuzzy algorithms is demonstrated by computer simulations.

• Journal of Welding and Joining
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• 제33권6호
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• pp.36-41
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• 2015

In the automotive industry, TWB hot stamping process is broadly adapted to reduce weight of the car and improve fuel efficiency. However, the process faces a problem of weakened strength of the welded zone after hot stamping process, due to the fact that Al-Si elements of the coating layer penetrating the welded zone. In this study, filler wires with high percentages of carbon and manganese is adapted during laser welding process to secure the strength of the fusion zone. In addition, wire feeding speed and laser welding speed are optimized by sample test.

• 품질경영학회지
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• 제31권1호
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• pp.123-131
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• 2003

This paper considers a six sigma project for reducing the defects rate of the welding process in manufacturing firms. The project follows a disciplined process of five macro phases. define, measure, analyze, improve and control(DMAIC). The need of customers is used to identify critical to quality(CTQ) of project. And a process map is used to identify process input factors of CTQ. Four key process input factors are selected by using an input factor evaluation of teams; an interval of welding, an abrasion, an electric current and a moving freely. DOE is utilized for finding the optimal process conditions of the three key process input factors. Another one key input factor improved to welding machine. The six sigma level of defects rate becomes a 2.01 from a 1.61 at the beginning of the project.

• 소성∙가공
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• 제26권2호
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• pp.115-120
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• 2017

Porthole extrusion process is a very effective metal forming process to produce aluminum profiles with hollow sections. The structure of porthole extrusion die is very complex. In this process, the billet is divided by porthole bridge, and then the divided billet is welded in the welding chamber. The welding pressure in the welding chamber is very important. The higher welding pressure improves the quality of the aluminum profiles. Therefore, the objective of this study is to develop a new porthole extrusion die for improving the welding pressure in the welding chamber by using numerical analysis. The effectiveness of the new porthole extrusion die was verified by using numerical analysis. Through numerical analysis, the welding pressures in the welding chamber between the new porthole die and the conventional porthole die were compared with each other.