• Title, Summary, Keyword: Arc welding

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A Study on Development of Arc Sensor for Arc Welding Robot Using Consumable Electrode (소모성 전극을 사용하는 아크용접 로봇을 위한 아크센서 개발에 관한 연구)

  • 이승영;문형순;나석주;장영주;안병규
    • Journal of Welding and Joining
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    • v.11 no.3
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    • pp.22-33
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    • 1993
  • Arc sensor is indispensable to arc welding robot systems for compensating the joint misalignment such as mismatch of the workpiece, ill-conditioned positioner and thermal deformation during welding. Furthermore, the amount of these mismatches cannot be preivously expected, and changes from time to time. There are many kinds of seam trackers for correcting the welding path of the robot, where non-contact type sensors arc prevalently used in arc welding robot systems. In this study, an arc sensor was developed for GMA and FCA welding robot system. Since the arc sensor uses the arc characteristics during welding, the operating principle of the arc sensor must be adjusted according to the welding condition. Especially in GMA welding with the $CO_{2}$ shielding gas, the welding arc is not stable because of the short circuit and non-axial globular transfer mode of the molten droplet. In this study, the 2nd order least square curve fitting algorithm was adopted and the applicability of this algorithm was investigated for robot welding systems. For easy usage of the arc sensor, the operating parameters for arc sensor were limited to eight which can be easily determined by the operator.

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A Study on the Development of Arc Length Estimation Method in FCAW (FCAW에서의 아크 길이 추정 방법 개발에 관한 연구)

  • Bae, Kwang-Moo;Cho, Sang-Myung
    • Journal of Welding and Joining
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    • v.27 no.3
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    • pp.67-72
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    • 2009
  • The flux cored arc welding (FCAW) process is one of the most frequently employed and important welding process due to high productivity and excellent workability. The process is performed either as an automated process or as a semi-automatic process. In FCAW process, welding voltage has been considered as a qualitative indication of arc length. But it is necessary to let welding operators know, maintain and manage the arc length directly by estimating and displaying it. In this study, to develop arc length estimation technique, we measured a welding circuit resistance($R_sc$) and then we calculated welding circuit voltage drop($V_sc$). Also, we measured arc peak voltage($V_ap$). By subtracting $V_sc$ from $V_arc$, we can easily calculate net arc voltage drop($V_arc$). Consequently, we suggested arc length estimating equation and basic algorithm by regressive analyzing the relationship between net arc voltage drop($V_arc$) and real arc length(Larc) measured by high speed camera. Therefore, arc length can be predicted by just monitoring welding current and voltage.

Technology on Arc Welding Machine of Aluminum by Digital Control (디지털 제어를 이용한 알루미늄 아크 용접기의 기술현황)

  • Lee, Chang-Je;Kim, Yu-Chan;Kim, Jong-Do
    • Journal of Welding and Joining
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    • v.31 no.1
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    • pp.26-32
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    • 2013
  • Recently, welding technology of nonferrous metals which were difficult to implement by arc welder has become available through digitalization of arc welding machine. Among them, the welding quality improvement of aluminum welding is very noticeable. These results increase the arc stability by controlling arc current and voltage waveform precisely, and control wire feed speed by synchronizing with arc current which the feed rate of filler wire is controlled by a precise motor control of servomotor and not by a simple constant speed feeding. Not only through the hardware digitalization of arc welding machine but also through advance of software of arc welding, it became possible to implement a certain level of welding quality by a simple operation. These led to CMT welding process implementation which requires low heat input than current arc welding and highly increased the applicability of the aluminum welding.

A Study on the Development of Arc Sensor for Flux Cored Arc Welding Process and its Application for Seam Tracking (Flux Cored Arc용접용 아크센서의 개발 및 이를 이용한 용접선 추적에 관한 연구)

  • 김수영;이승영;나석주
    • Journal of Welding and Joining
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    • v.10 no.4
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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.

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A Study on the Calculating Method of the Heat Input Efficiency in Arcspot Welding (아크 스폿 용접의 입열효율 계산 방법에 관한 연구)

  • Jang, Kyoung-Bok;Cho, Sang-Myoung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.7
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    • pp.1065-1070
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    • 2003
  • In arc spot welding process, the arc is not moving and heat input is concentrated in one spot so that the heat input efficiency of arc is higher than that of GMAW. In other words, the heat input efficiency of arc change during weld time because arc start is done in spot and weld metal is filled. Therefore, the heat input model of arc spot welding should be different from that of general GMAW. In present study, the calculating model of heat input efficiency in arc spot welding was suggested by temperature monitoring near spot in arc spot welding of copper plate. The result showed that the heat input efficiency of arc was changed three times during weld time. The accuracy of calculating method of heat input efficiency was verified by heat transfer analysis of arc spot welding process using finite element method.

Position welding for internal welded specimen using laser-GMA hybrid welding (내면 용접부재의 전자세 레이저-아크 하이브리드 용접 연구)

  • Ahn, Young-Nam;Kim, Cheolhee;Kim, Jeonghan
    • Journal of Welding and Joining
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    • v.33 no.1
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    • pp.54-60
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    • 2015
  • Laser-arc hybrid welding has been considered as an effective pipe girth welding process since early 2000's. Tolerance for fit-up offsets such as gap and edge misalignment is one of most important requirements in pipe girth laser-arc hybrid welding, and several approaches using parameter optimization, a laser beam scanning and an arc oscillation have been tried. However the required offset tolerance has not been fully accomplished up to now and laser-arc hybrid welding has not been widely applied in pipeline construction than expected, despite of its high welding speed and deep penetration. In this study, internal welding was adopted to ensure the offset tolerance and sound back bead. The effect of welding parameters on bead shape was investigated at the flat position. Also tolerances for gap and edge misalignment were verified as 0.5 mm and 2.0 mm, respectively. The position welding trials were conducted at several welding positions from the flat to the overhead position in a downward direction. With the fixed welding speed, arc current for gas metal arc welding current and laser output power, adequate welding voltages for gas metal arc welding were suggested for each position.

The Experimental Study of Flux Improvement of Wet Underwater Arc Welding Electrode (습식 수중 용접봉의 피복제 개발에 관한 기초연구)

  • Kim, Min-Nam;Kang, Jung-Gun
    • Journal of Ocean Engineering and Technology
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    • v.13 no.4
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    • pp.28-36
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    • 1999
  • Wet underwater arc welding process is investigated by using experimentally developed flux coated underwater arc welding electrode and SS400 steel plate of 12mm thickness as base metal. Three kinds of different flux covered wet arc welding electrode of 4mm diameter(BK-01, BK-02, BK-03) are individually developed, and one of the improved underwater welding electrode (BK-03) may be put to practical use for underwater wet arc welding process. The results obtained from this experimental study are as follows : 1. Arc stability of developed underwater wet welding electrode is better than that of the domestic covered arc welding electrode. 2. Workability of welding electrode, remove ability of slag and bead appearances using improved underwater wet welding electrode are remarkably better than that of others. 3. Heat affected zone of test specimen welded in the underwater gets to become a lot smaller than that of test specimen welded in the air, and the maximum hardness of heat affect zone of developed underwater wet welding electrode is lower to that of domestic arc welding electrode.

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Evaluation of Gas Metal Arc Welding Characteristics according to Contact Tip Materials (GMA용접에서 콘택트 팁 재질에 따른 용접특성 평가)

  • Kim, Dong Yoon;Hwang, In Sung;Kim, Dong Cheol;Kang, Moon Jin
    • Journal of Welding and Joining
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    • v.32 no.6
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    • pp.35-40
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    • 2014
  • The contact tip for gas metal arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. If the contact tip is damaged, it is a cause of lowering the welding productivity due to removal of welding defects and replacement of contact tip. In case of the use of a contact tip for a long time the arc is unstable because the processed hole in the contact tip center is larger, and the variation of aiming position of the welding wire causes a seam tracking error. In this study, gas metal arc welding experiments using contact tip of three different materials were performed. The contact tips with Cu-P, Cu-Cr, and Cu-ODS were used at the experiments, and the welding characteristics by each contact tip were evaluated. After welding contact tip appearance, welding spatter adhesion amount of the nozzle, and weld bead appearance were evaluated. The welding current and welding voltage were measured to verify arc stability during arc welding.

Development of Arc Sensor Model Using Regression Analysis and Artificial Neural Network in $CO_2$ Arc Welding (탄산 가스 아크 용접에서 회귀 분석과 인공 신경망을 이용한 아크 센서 모델 개발)

  • 김용재;이세헌
    • Journal of Welding and Joining
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    • v.20 no.6
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    • pp.776-782
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    • 2002
  • The experimental model of arc sensor in $CO_2$ arc welding has been individually developed according to welding condition and welding procedure. Therefore, the development of new arc sensor having the features of all conventional arc sensor is important in point of its application to various welding environment. In this study, the arc sensor experimental models comprised of a regression model and noise term were formulated using conventional arc sensing algorithm such as current area difference, current integration difference and weaving end current difference method, and their features were observed. The new regression arc sensor model was suggested using multiple linear regression analysis using current variables as independent variables of regression analysis. The artificial neural network model was also suggested where current variables and offset distance was used input/out variables of input/output node.

A Study on the Arc Position which Influence on Quality of Plug Welding in the Vehicle Body (차체 플러그 용접품질에 영향을 미치는 아크 위치에 대한 실험적 기초 연구)

  • Lee, Kyung-Min;Kim, Jae-Seong;Lee, Bo-Young
    • Journal of Welding and Joining
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    • v.30 no.3
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    • pp.66-70
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    • 2012
  • Welding is an essential process in the automotive industry. Most welding processes that are used for auto body is spot welding. And $CO_2$ arc welding is used in a small part. In production field, $CO_2$ arc welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in $CO_2$ arc welding process frequently. But $CO_2$ arc welding process should be used at robot interference parts and closed parts where spot welding couldn't. $CO_2$ welding is divided into lap welding and plug arc spot welding. In case of plug arc spot welding, burn through and under fill were caused in various welding environment such as different thickness combinations of base metal, teaching point, over the two steps welding and inconsistent voltage/current. It makes some problem like poor quality of welding area and decrease the productivity. In this study, we will evaluate the effect of teaching point through the weld pool behavior and bead geometry in the arc spot welding at the plut hole. Welding position is horizontal position. And galvanized steel sheet of 2.0mm thickness that has plug hole of 6mm diameter was used. Teaching point was changed by center, top, bottom, left and right of the plug hole. At each condition, the phenomenon of weld pool behavior was confirmed using a high-speed camera. As the result, we find the center of plug hole is the most optimal teaching point. In the other teaching point, under fill was occurred at the plug hole. This phenomenon is caused by gravity and surface tension. For performance of arc spot welding at the plug hole, the teaching condition should be controlled at a center of plug hole.