• Title/Summary/Keyword: Fillet Welding

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A Experiment Study for Welding Optimization of fillet Welded Structure (필릿 용접 구조물의 용접 최적화률 위한 실험적 연구)

  • Kim, Il-Soo;Na, Hyun-Ho;Kim, Ji-Sun;Lee, Ji-Hye
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.9
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    • pp.1054-1061
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    • 2011
  • GMA welding process is a production process to improve productivity for the provision of higher quality of material, These includs numerous process variables that could affect welding quality, productivity and cost savings. Recently, the welding part of construction equipment had frequent failure of major components in the welding part of each subsidiary material due to shock which is very poor according to the welding part. Therefore, the implementation of sound welding procedure is the most decisive factor for the reliability of construction machinery. The data generated through experimens conducted in this study has validated its effectiveness for the optimization of bead geometry and process variables is presented. The criteria to control the process parameters, to achieve a healthy bead geometry. This study has developed mathematical models and algorithms to predict or control the bead geometry in GMA fillet welding process.

Determination of Preheating Temperature for Box Girder Welding (강교용 박스거더의 용접예열 온도 선정에 관한 연구)

  • Cho, Jae-Hun;Moon, Seung-Jae;Yoo, Hoseon
    • Plant Journal
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    • v.7 no.1
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    • pp.49-55
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    • 2011
  • This study analyzed causes and status of cracks to suggest preventives for welding cracks generated on fillet welding zone of atmosphere corrosion resisting steel box girder. Penetrant testing, a sort of non-destructive testing, was conducted for inspection of crack status on welding zone. As a result of test, welding cracks were found on the point of start, center and end to fillet welding zone of 32 mm-thickness. The result of carbon equivalent composition of materials was 0.452%. According to welding specification, to preheat prevent welding crack, preheat temperature of $100{\sim}200^{\circ}C$ should be kept before welding execution. It was failed to keep preheat temperature because it had been executed on winter season and the structure of box girder had wide heat transfer area. As a result of examination of time varying preheating temperature of 32mm-thickness material, it was understood that preheat temperature of above $230^{\circ}C$ on both 130mm-long sides of welded joint can prevent welding crack.

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A Study on Development of Algorithm for Seam Tracking by Considering Weld Defects in Horizontal Fillet Welding (수평필릿용접에서 용접결함을 고려한 용접선 자동추적 알고리즘개발에 관한 연구)

  • 문형순;나석주
    • Proceedings of the KWS Conference
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    • pp.139-141
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    • 1996
  • Among various welding parameters, the welding current which is inversely proportional to the tip-to-workpiece distance in GMAW is an essential parameter to monitor the GMAW process of horizontal fillet joints. For the case of weld defect such as overlap in horizontal fillet welding, therefore, the signal processing for process monitoring or automatic seam tracking should be modified by considering the weld pool surface geometry including the corresponding weld defect. In other words, the adequate signal processing algorithm is indispensible to improve the performance of the arc sensor. However, arc sensor algorithm already developed usually focus on weld seam tracing but do not considering the weld qualities. In this paper, various experiments were carried out to investigate the tendencies of the weld defects when weaving motion is added, and the experimental method based on 2$^n$ factorial design was proposed for deriving the mathematical model between the leg length and the various welding conditions. Moreover, a signal processing method based on the artificial neural network(Adaptive Resonance Theory) was proposed far discriminating the current signal of sound weld beads from that of weld beads with overlap. Finally, the algorithm for weld seam tracking combined with the mathematical modeling and the signal processing method was carried out to track the weld line in conjunction with the improvement of the weld qualities. The reliability of the proposed algorithms were evaluated through various experiments, which showed that the proposed algorithms could be effectively used for arc welding automation.

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A Experiment Study for Selection of Welding Condition of fillet Welded Structure (필릿용접 구조물의 용접조건 선정을 위한 실험적 연구)

  • Na, Hyun-Ho;Kim, Ill-Soo;Kim, Ji-Sun;Lee, Ji-Hye
    • Journal of Welding and Joining
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    • v.29 no.4
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    • pp.41-47
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    • 2011
  • GMA welding process is a production process to improve productivity for the provision of higher welding quality of material. These includes numerous process variables that could affect welding quality, productivity and cost savings. Recently, the welding part of construction equipment had frequent failure of major components in the welding part of each subsidiary material due to shock which is very poor according to the welding part. Therefore, the implementation of sound welding procedure is the most decisive factor for the reliability of construction machinery. The data generated through experiments conducted in this study has validated its effectiveness for the optimization of bead geometry and process variables is presented. The criteria to control the process parameters, to achieve a good bead geometry. This study has developed mathematical models and algorithms to predict or control the bead geometry in GMA fillet welding process.

The Weldability of the Dissimilar Magnesium Alloy Welded by Fiber Laser (파이버 레이저를 이용한 이종 마그네슘 합금의 용접성에 관한 연구)

  • Kim, Jong-Do;Kim, Young-Sik;Song, Mook-Keun;Lee, Jung-Han
    • Journal of Welding and Joining
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    • v.31 no.2
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    • pp.63-68
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    • 2013
  • Magnesium alloys have gained increased attention in recent years as the structural materials, because of their attractive properties such as good specific strength, excellent sound damping capability. However, to expand their applications, a reliable joining process is absolutely necessary. In this study, a CW fiber laser was used to investigate the lap weldability of sand casting and wrought magnesium alloys. The effect of defocused distance on lap weldability was examined, and it was found that spatters always generated at the around focused distance because of the high power density of the laser beam. Thus, defocused distance was required to obtain sound welds. In addition, the application of fillet welding was evaluated for minimizing the affect of sand casting magnesium alloy that have relatively poor weldability. As a result of this study, we could confirm good weldability without weld defects.

Microstructural Characteristics of T-bar Welding Zone for Shipbuilding and Offshore Plants (조선해양플랜트용 T-bar 용접부의 미세조직학적 특성에 관한 연구)

  • Hwang, Y.J.;Choi, Y.S.;Jang, J.H.;Lee, S.I.;Gong, K.Y.;Lee, DG.
    • Transactions of Materials Processing
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    • v.27 no.5
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    • pp.296-300
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    • 2018
  • T-type and H-type section steels were generally used in shipbuilding and offshore plants and were produced by welding technology. These section steels were produced by handwork, and the supplying amounts can't satisfy the demand amounts of the fabrication companies. In case of fillet welding, there are some gaps in weld-joint region due to no groove preparation processing and it can occur crack initiation in the welded region. It is important to evaluate the microstructural and mechanical properties of welded zone to solve these problems. To satisfy the demand amounts of T-bar parts, automatic welding technology was introduced and several conditions as a function of welding speeds were carried out to improve the manufacturing speed. Heat-affected zone may be affected by variation of heat input and cooling rate through automatic welding speed and welding speed is necessary to be optimized. In this study, fusion zone and heat-affected zone were investigated by microstructural and mechanical analysis and were evaluated whether the welded parts were sound or not.

THE PREVENTION OF THE LONGITUDINAL DEFORMATION DUE TO FILLET WELDING BY USING INDUCTION HEATING

  • Park, Jeong-Ung;Lee, Chin-Hyung;Chang, Kyong-Ho
    • Proceedings of the KWS Conference
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    • pp.816-825
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    • 2002
  • During the manufacture of a ship, longitudinal deformation is produced by fillet welding on the BuiltUp beam used to improve the longitudinal strength of a ship. This deformation needs a correcting process separate from a manufacture process and decreases productivity and quality. This deformation is caused by welding moment, which is the value multiplied the shrinking force due to welding by the distance from the neutral axis on a cross section of Built-Up beam. This deformation can be offset by generating a moment which is the same magnitude with and is located in an opposite direction to the welding moment on web plate by induction heating. Accordingly, this study clarifies the creation mechanism of the longitudinal deformation on Built-Up beam with FEM analysis and presents the preventative method of this deformation by induction heating basing the mechanism and verifies its validity through analysis and experiments. The induction heating used here is performed by deciding its location and quantity with experiments and simple equations and by applying them to areal structure.

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A Study on the Prediction of Bead Geometry for Lab Joint Fillet Welds Using Sensitivity Analysis (민감도 분석을 이용한 겹치기 필릿용접부 비드형상 예측에 관한 연구)

  • Jeong, Jae-Won;Kim, Ill-Soo;Kim, Hak-Hyoung;Kim, In-Ju;Bang, Hong-In
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.6
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    • pp.49-55
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    • 2008
  • Arc welding process is one of the most important technologies to join metal plates. Robotic welding offers the reduced manufacturing cost sought, but its widespread use demands a means of sensing and correcting for inaccuracies in the part, the fixturing and the robot. A number of problems that need to be addressed in robotic arc welding processes include sensing, joint tracking, and lack of adequate models for process parameter prediction and quality control. Problems with parameter settings and quality control occur frequently in the GMA(Gas Metal Arc) welding process due to the large number of interactive process parameters that must be set and accurately controlled. The objectives of this paper are to realize the mapping characteristics of bead width using a sensitivity analysis and develop the neural network and multiple regression method, and finally select the most accurate model in order to control the weld quality(bead width) for fillet welding. The experimental results show that the proposed neural network estimator can predict bead width with reasonable accuracy, and guarantee the uniform weld quality.

Development of Simple Prediction Model for Fillet Welding Deformation (필릿 용접변형에 대한 간이 예측 모델 개발)

  • 김상일
    • Journal of the Society of Naval Architects of Korea
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    • v.40 no.2
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    • pp.49-56
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    • 2003
  • The welding deformation of a hull structure in the shipbuilding industry is Inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurateprediction method which can explicitly account for the influence of various factors on the welding deformation. The validity of the prediction method must be also clarified through experiments. This paper is aimed at deriving the simple prediction model for fillet welding deformations. For this purpose, the thermal elasto-plastic analysis varying the welding conditions and plate thickness has been performed. On the basis of numerical results, the formulae for angular distortion and transverse shrinkage have been derived through the regression analysis. Experimental work has been also carried out to clarify the validity of numerical results. It has been found that the numerical results show a good agreement with those of experiments