• International Journal of Korean Welding Society
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• 제3권2호
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• pp.46-52
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• 2003

The refinement of microstructure and phase transformation near the interface of pure copper/carbon steel dissimilar metals joints with various friction welding parameters have been studied in this paper. The microstructure of copper and carbon steel joints were changed to be a finer grain compared to those of the base metals due to the frictional heat and plastic deformation. The microstructure of copper side experienced wide range of deformed region from the weld interface and divided into very fine equaxied grains and elongated grains. Especially, the microstructures near the interface on carbon steel were transformed from ferrite and pearlite dual structure to fine ferrite, grain boundary pearlite and martensite due to the welding thermal cycle and rapid cooling rate after welding. These microstructures were varied with each friction welding parameters. The recrystallization on copper side is reason for softening in copper side and martensite transformation could explain the remarkable hardening region in carbon steel side.

• 한국해양공학회지
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• 제13권3호통권33호
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• pp.83-91
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• 1999

Taking a view of joining by welding the IN713C to SCM440 and SCM415 steel in production of turbochargers, the frictin welding process may be utilized as a new approach for joining them of other conventional welding processes. It is because the friction welding has more technical and technical and economic advantages than the other welding processes. As this welding process has the characteristics such as curtaliment of production time and materials and cost reduction, etc.. So, this paper deals with determining the preper friction welding condition and analyzing various mechanical properties of friction welded joints of the super heat resisting steel to alloy stee(IN713C to SCM440 and SCM415). And the in-process real-time weld quality evaluation technique by acoustic emission during friction welding of IN713C to SCM440 and SCM415 steels with higher confidence and relibility has been much required even though it might be the first trial approach for developing it. Then, this first study aimed to develop the optimization of dissimilar friction welding of heat resisting steels (INC713 to SCM440, SCM415) for turbine, considering on strength and toughness.

• Journal of Welding and Joining
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• 제10권4호
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• pp.190-198
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• 1992

Among the variety of welding processes available, the flux cored arc welding is one of the most frequently used process, because of its wide range of application and high productivity. The weld joint tracking is indispensable to improve the flexibility of the arc welding robot application for the flux cored arc welding (FCAW) process. In this study, an arc sensor which utilizes the electrical signal obtained from the welding arc itself was developed for weld joint tracking in FCAW. Because a model of the welding arc in flux cored arc welding was required to develop the arc sensor, a mathematical model was proposed by analysing the welding arc behaviour, and also an experimental model by using the factorial experiment and least square method. For overcoming the fluctuation in the welding current signal during tracking the weld joint, it was fitted to a curve which is inversely proportional to a trace of tip-to-workpiece distance by using the quadratic curve-fitting method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1137-1140
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• 2005

Automatic welding has been used frequently on pipeline projects. The productivity and reliability are most essential features of the automatic welding system. The mechanized GMAW process is the most widely used welding process and the carriage and band system is most effective welding system for pipeline laying. This application-oriented paper introduces new automatic welding equipment for pipeline construction. It is based on cutting-edge design and practical welding physics to minimize downtime. This paper also describes the control system which was designed and implemented for new automatic welding equipment. The system has the self diagnostic function which facilitates maintenance and repairs, and also has the network function via which the welding task data can be transmitted and the welding process data can be monitored. The laser vision sensor was designed for narrow welding groove in order to implement higher accuracy of seam tracking and fully automatic operation.

• International Journal of Korean Welding Society
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• 제1권2호
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• pp.36-44
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• 2001

To get the appropriate welding process variables, mathematical modeling in conjunction with many experiments is necessary to predict the magnitude of weld bead shape. Even though the experimental results are reliable, it has a difficulty in accurately predicting welding process variables for the desired weld bead shape because of nonlinear and complex characteristics of welding processes. The welding condition determined for the desired weld bead shape may cause the weld defect if the welding current/voltage/speed combination is improperly selected. In this study, the $2^{n-1}$ fractional factorial design method and correlation parameter were used to investigate the effect of the welding process variables on the fillet joint shape, and the multiple non-linear regression analysis was used for modeling the gas metal arc welding(GMAW）parameters of the fillet joint. Finally, a fuzzy rule-based method and a neural network method were proposed so that the complexity and non-linearity of arc welding phenomena could be effectively overcome. The performance of the proposed neuro-fuzzy system was evaluated through various experiments. The experimental results showed that the proposed neuro-fuzzy system could effectively check the welding conditions as to whether or not weld defects would occur, and also adjust the welding conditions to avoid these weld defects.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1997년도 추계학술대회 학술발표 논문집
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• pp.189-193
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• 1997

Generally, though we use the vision sensor or arc sensor in welding process, it is difficult to define the welding parameters which can be applied to the weld quality control. Especially, the important parameters is Arc Voltage, Welding Current, Welding Speed in arc welding process and they affect the decision of weld bead shape, the stability of welding process and the decision of weld quality. Therefore, it is difficult to determine the unique relationship between the weld bead geometry and the combination of various welding condition. Due to the various difficulties as mentioned, we intend to use Fuzzy Logic and Neural Network to solve these problems. Therefore, the combination of Fuzzy Logic and Neural network has an effect on removing the weld defects, improving the weld quality and turning the desired weld bead shape. Finally, this system can be used under what kind of welding process adequately and help us make an estimate of the weld bead shape and remove the weld defects.

• 동력기계공학회지
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• 제18권2호
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• pp.50-56
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• 2014

Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, for the friction welding with tube-to-tube shape, the feasibility of industry application was determined using analyzing mechanical properties of weld and optimized welding variables was suggested. In order to accomplish this object, rotating speed, friction heating pressure, and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. Weld characteristic was investigated in terms of weld shape and metal loss, and 7mm of metal loss was regarded as the optimal metal loss. By tensile test, tensile strength and yielding strength was measured and fracture was occurred at base metal. In order to optimize the welding condition, fitness function was defined with respect to metal loss and yielding strength and the fitness values for each welding condition could be calculated in experimental range. Consequently, we set the optimal welding condition as the point which had maximum value of fitness function. As the result of this paper the optimal welding variables could be suggested as rotating speed was 1300 rpm, friction heating pressure was 15 MPa, and friction heating time was 10 sec.

• Journal of Welding and Joining
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• 제23권4호
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• pp.41-47
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• 2005

Generally, the use of robots in manufacturing industry has been increased during the past decade. GMA(Gas Metal Arc) welding process is an actively Vowing area, and many new procedures have been developed for use with high strength alloys. One of the basic requirement for the automatic welding applications is to investigate relationships between process parameters and bead geometry. The objective of this paper is to develop a new approach involving the use of neural network and multiple regression methods in the prediction of bead geometry for GMA welding process and to develop an intelligent system that visualize bead geometry in order to employ the robotic GMA welding processes. Examples of the simulation for GMA welding process are supplied to demonstrate and verify the proposed system developed using MATLAB. The developed system could be effectively implemented not oかy for estimating bead geometry, but also employed to monitor and control the bead geometry in real time.

• Journal of Welding and Joining
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• 제30권2호
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• pp.59-64
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• 2012

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body are spot welding and $CO_2$ welding are used in a small part. In production field, $CO_2$ welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in $CO_2$ welding process frequently. But $CO_2$ welding process should be used at robot interference parts and closed parts where spot welding couldn't. Because of the 0.65mm ~ 2.0mm thickness steel sheet were used in the automotive industry, poor quality of welding area such as burn through and under fill were happened frequently in $CO_2$ process. In this paper, we will study about the penetration depth which gives a huge impact on burn through changing a degree of base metal, welding position and torch angle. Voltage, current and welding speed were fixed but degree of base metal, welding position and torch angle were changed. And Cold- Rolled(CR) steel sheet was used. Penetration depth was analysed by multiple regression analysis to derive approximate calculations. And reliability of approximate calculations were confirmed through additional experiments. As the results of this research, we confirmed the effect of torch and plate angle to bead shape. And we present a possibility that can simulate more accurate to weld geometry, as deduced the verification equations that has tolerance of less than 21.69%.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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• pp.229-233
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• 1997

The demand to increase productivity and quality, the shortage of skilled labour and the strict health and safety requirements have led to the development of the automated welding process to deal with many of the present problems of welded fabrication. To make effective use of the automated arc welding process, it is imperative that a mathematical model, which can be programmed easily and fed to the robot, should be developed. The objectives of the paper are to develop the mathematical equations (linear and curvilinear) for study of the relationship between process variables and bead geometry by employing a standard statistical package program, SAS and to choose the best model for automation of the $CO_2$ gas arc welding process. Mathematical models developed from experimental results can be employed to control the process variables in order to achieve the desired bead geometry based on weld quality criteria. Also these equations may prove useful and applicable for automatic control system and expert systems.