• Title/Summary/Keyword: Weld pool

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Weld Pool Analysis by Driving force Acting on the Weldment (용접부에 작용하는 구동력에 의한 용융풀 거동 분석)

  • 김일수;김학형;조선영;강봉용;강문진;유관종
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.04a
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    • pp.184-190
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    • 2004
  • Over the last few years, there has been a growing interest in quantitative representation of the weld pools in order to relate the processing conditions to the driving forces of the weldment produced and to use this information for the optimization of the welding process. A theoretical model offers a powerful alternative to check the physical concepts of the welding process and the effects of driving forces. To solve this problem, a 2-D thermo-fluid model were eve loped for determining temperature and velocity distribution for the GMA welding process.

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Study on the Simultaneous Control of the Seam Tracking and Leg Length in a Horizontal Fillet Welding Part 2: Seam Tracking

  • Moon, H.S.;Na, S.J.
    • International Journal of Korean Welding Society
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    • v.1 no.1
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    • pp.31-38
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    • 2001
  • For the horizontal fillet welding with one plate in a vertical position, there will be a higher tendency of weld metal falling down rather than for the butt-welding in flat position. Such phenomenon could bring about the overlap or deflection of weld pool, and consequently induce the poor mechanical strength of weldments. Therefore, a precise position control of welding torch in conjunction with the weld qualify plays an important role in welding robot applications. In the present study, an experimental method was proposed for deriving a mathematical model between the leg length and the welding conditions. Finally, an algorithm was proposed for weld seam tracking and improvement of the weld quality. The reliability of the proposed algorithm was evaluated through various experiments, which showed that the proposed algorithm can be very effective for tracking the weld line and simultaneously achieving the sound weld bead.

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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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    • 1996.10a
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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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INVESTIGATIONS ON VARIABLE WELD PENETRATIONS IN GTA WELDING OF AUSTENITIC AND MARTENSITIC STAINLESS STEELS

  • Puybouffat, Sylvain;Chabenat, Alain;Boudot, Cecile;Marya, Surendar
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.752-756
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    • 2002
  • Variable weld bead penetrations related to the base metal chemistry of stainless steels in GTA welding have been under constant investigations due to their industrial implications. It has been proposed that among other elements, the sulfur content of steels determines the weld pool geometry, particularly its penetration. It is suggested that the surface tension temperature gradient of steels becomes positive with appropriate dosing in sulfur and results in inward melt flow, propitious for deeper welds. However, the chemistry of industrial steels is complex due to the presence of multiple minor elements either deliberately added or remnant impurity traces. With this in view, investigations on 41 austenitic and nine martensitic stainless steels were carried to see if there existed any possible relation between the weld profile and some of the designated elements. The results suggest no direct correlation between sulfur or any other major or trace element and weld penetration. At first glance the results are contradictory to what is often asserted.

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Prediction of Nuggest Shape by Finite Element Modeling in Arc-spot Welding (유한요소 모델링을 이용한 아크 스폿 용접의 너깃 형상 예측)

  • 황종근;장경복;김기순;강성수
    • Journal of Welding and Joining
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    • v.17 no.2
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    • pp.84-90
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    • 1999
  • The shape of weld nuggest in arc spot welding of 304 stainless steel was found by searching thermal history of a weld joint through a three-dimensional finite element model. The problem consists of one in which the finite element mesh is growing continuously in time in order to accomodate metal transfer in arc spot welding using element rebirth technique. The analysis was performed on the basis of experimental results. The finite element program MARC, along with a few user subroutines, was employed to obtain the numerical results. Temperature-dependent thermal properties, stir effect in weld pool, effect of phase transformation, and the convective and radiative boundary conditions are included in the model. Numerically predicted shape of weld nuggest is compared with the experimentally observed shape.

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