• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.1404-1407
• /
• 1996

A quality monitoring system in butt welding process is proposed to estimate weld pool sizes. The geometrical parameters of the weld pool such as the top bead width and the penetration depth plus half back width are utilized to prove the integrity of the weld quality. The monitoring variables used are the surface temperatures measured at three points on the top surface of the weldment. The temperature profile is assumed that it has a gaussian distribution in vertical direction of torch movement and verify this assumption through temperature analysis. A neural network estimator is designed to estimate weld pool size from temperature informations. The experimental results show that the proposed neural network estimator which used gaussian distribution as temperature information can estimate the weld pool sizes accurately than used three point temperatures as temperature information. Considering the change of gap size in butt welding, the experiment were performed on various gap size.

• Journal of Welding and Joining
• /
• 제9권3호
• /
• pp.34-40
• /
• 1991

An automatic welding system was constructed with a personal computer to capture the welding data in addition to vision seam tracking for the gas metal arc welding process. The monitoring of welding signals is composed of the acquisition of welding voltage and current, obtained by using two differential amplifiers and A/D converters, and processing of the measured data. Using interrupt handing circuit for time sharing, two jobs of seam tracking and monitoring were performed at the required sampling time. Relations between welding signals and various welding circumstances were analyzed from the experimental results.

• Journal of Welding and Joining
• /
• 제12권4호
• /
• pp.76-84
• /
• 1994

Droplet transfer modes due to welding conditions and the effect of Ca in welding wire on droplet transfer were investigated. Droplet transfer mode in CO$_{2}$ welding was classified into 2 modes, that is, short circuit and globular transfer, with increasing welding current and voltage. With increasing Ca content in wire, repulsive pressure due to vaporization of Ca was considerably increased. In short circuit transfer region, arcing time was increased and droplet transfer cycle was decreased, with increasing Ca content. In globular transfer region, welding condition for globular transfer was lower current region, with increasing Ca content.

• Journal of Welding and Joining
• /
• 제15권3호
• /
• pp.36-46
• /
• 1997

Dynamics of molten drop detachment in the Gas Metal Arc (GMA) welding is investigated using the Volume of Fluid(VOF) method. The electromagnetic effects are included in the formulation of the VOF method which has been widely used to analyze the dynamics of the fluid having a free surface. The molten drop geometry, pressure and velocity profiles within the drop are calculated numerically in the cases of globular and spray transfer modes. It appears that the velocity and current distribution affect metal detachment. It is found that the taper is formed and maintained during the spray transfer by the electromagnetic force. Predicted results show reasonably good agreement with the available experimental data which validates the application of the VOF method to metal transfer analysis.

• Journal of Welding and Joining
• /
• 제15권3호
• /
• pp.47-55
• /
• 1997

Dynamic characteristics of the short circuit mode are investigated using the Volume of Fluid (VOF) method. When the initial molten drop volume, contact area and wire feed rate are given, rate change of the molten bridge profiles, pressure and velocity distributions are predicted. The electromagnetic force with proper boundary conditions are included in the formulation to consider the effects of welding current. It is found that the molten metal is transferred to the weld pool mainly due to the pressure difference caused by the curvatures in the initial stage, and electromagnetic force becomes dominant factor in the final stage of short circuit transfer. Necking occurs at the contact position between the molten drop and weld pool, and the initial molten drop volume and welding current have significant effects on break-up time.

• Journal of Welding and Joining
• /
• 제12권4호
• /
• pp.151-161
• /
• 1994

FCAW has wide application in ship fabrication, maintenance and field erection. It has many advantages over SMAW.SAW and GMAW process. In many applications, the FCAW provides highquality weld metal. This method can reduce weld defects especially porosity and spatter. But the fatigue characteristics of those deposited metal have been rarely investigated. The purpose of this study is to investigate the cyclic stress-strain behavior and fatigue tests by the constant strain control were carried out on the rounded smooth specimen with deposited metal using the metal type flux cored wire. As the results of this study for the deposited metal welded by the metal type flux cored wire, the hardening or softening characteristics under cyclic load were investigated and cyclic stress-strain curve, strain-fatigue life curve, stress-strain function and fatigue life relation which are useful to estimate the fatigue life under the stress concentration condition were obtained.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2002년도 전력전자학술대회 논문집
• /
• pp.665-668
• /
• 2002

Joining thin aluminum alloy is difficult using most wilding techniques. Many of problems associated burn-through by the high heat input Common welding techniques are TIG, MIG, and MIG-PULSE welding. The VP-GMAW provides more control of the heat balance in the voiding arc by taking advantage of the different arc characteristics obtained with each of the two polarities. In this paper, we proposed new VP_GMA Welding method by control DSP 320C32, and the characteristic and experiment result-voltage, current, welding bead. penentraion by this method are presented

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2001년도 춘계종합학술대회
• /
• pp.369-373
• /
• 2001

In this paper, we proposes the steps adopted to construct the neural network model for GMAW welds. Conventional, automated process generally involves sophisticated sensing and control techniques applied to various processing parameters. Welding parameters are influenced by numerous factors, such as welding current, arc voltage, torch travel speed, electrode condition and shielding gas type and flow rate etc. In traditional work, the structural mathematical models have been used to represent this relationship. Contrary to the traditional model method, neural network models are based on non-parametric modeling techniques. For the welding process modeling, the non-linearity at well as the coupled input characteristics makes it apparent that the neural network is probably the most suitable candidate for this task. Finally, a suitable proposal to improve the construction of the model has also been presented in the paper.

• Journal of Welding and Joining
• /
• 제6권2호
• /
• pp.47-55
• /
• 1988

This paper reports on a study of the influence of welding variables on the weld shape of Al-7020 in pulse-GMA welding. Five variables, i.e., wire feed rate, peak pulse current, welding speed, welding votage, and pulse frequency were investigated for their effects on the weld shape. From the results of the 2$^{n-1}$ fractional factorial design, quantitative effects of each variable and the interaction of two variables were obtained, and consequently wire feed rate, welding voltage, and welding speed were determined as the main welding variables. Supplementary experiment was performed for ivestigating the detailed relationship between the main variables nd the seld shape. In this experiment, the penetation of the seldment increased when the wire feed rate was raised, nad the bead width increased when the welding voltage was raised or the welding speed was reduced.d.

• Journal of Welding and Joining
• /
• 제14권3호
• /
• pp.2-11
• /
• 1996

용접 능률과 품질에 영향을 미치는 여러가지 요인들 중에서 용접기의 성능은 가장 중요한 요소의 하나이다. 이러한 점에서 숙련도에 주로 의존하던 종래의 용접성 에 대한 관념이 바뀌어야 하며, 품질 표준화 작업의 일환으로 용접기 제어 성능의 향상도 절실하다고 하겠다. 용접품질의 제어성능에 직접 영향을 주는 요소가 무엇인지 를 생각해 볼때, 그것은 바로 용접부에 공급되는 에너지의 제어, 용접 물리현상의 이해와 관찰을 기초로 적절한 함수의 설정과 함께 이들의 관리가 필요함을 알게된다. system화된 용접기는 이들 용접의 물리적 현상과 그 해석 결과를 어떤 방식으로든 이용하고 제어하여야 할 것이므로, 용접기 전력제어의 중요성과 함께 제어 소자의 성능은 물론 제어 algorithm의 최적화가 필수 요소임을 실감하게 된다. 따라서, 여기 에서는 제조 공정에서 가장 중요한 용접 공정의 하나인 아크 용접(GMAW, GTAW) system 의 개요와 특성 및 향후 기술개발의 과제에 대하여 기술하고자 한다.