• Title/Summary/Keyword: Weld bead

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A Study on Real-time Control of Bead Height and Joint Tracking Using Laser Vision Sensor

  • Kim, H. K.;Park, H.
    • International Journal of Korean Welding Society
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    • v.4 no.1
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    • pp.30-37
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    • 2004
  • There have been continuous efforts on automating welding processes. This automation process could be said to fall into two categories, weld seam tracking and weld quality evaluation. Recently, the attempts to achieve these two functions simultaneously are on the increase. For the study presented in this paper, a vision sensor is made, a vision system is constructed and using this, the 3 dimensional geometry of the bead is measured on-line. For the application as in welding, which is the characteristic of nonlinear process, a fuzzy controller is designed. And with this, an adaptive control system is proposed which acquires the bead height and the coordinates of the point on the bead along the horizontal fillet joint, performs seam tracking with those data, and also at the same time, controls the bead geometry to a uniform shape. A communication system, which enables the communication with the industrial robot, is designed to control the bead geometry and to track the weld seam. Experiments are made with varied offset angles from the pre-taught weld path, and they showed the adaptive system works favorable results.

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A Study on Development of System for Prediction of the Optimal Bead Width on Robotic GMA Welding (로봇 GMA용접에 최적의 비드폭 예측 시스템 개발에 관한 연구)

  • 김일수
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.7 no.6
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    • pp.57-63
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    • 1998
  • An adaptive control in the robotic GMA welding is employed to monitor information about weld characteristics and process parameters as well as to modify those parameters to hold weld quality within acceptable limits. Typical characteristics are the bead geometry, composition, microstructure, appearance, and process parameters which govern the quality of the final weld. The main objectives of this thesis are to realize the mapping characteristics of bead width through learning. After learning, the neural estimation can estimate the bead width desired form the learning mapping characteristic. The design parameters of the neural network estimator(the number of hidden layers and the number of nodes in a layer) are chosen from an estimation error analysis. A series of bead of bead-on-plate GMA welding experiments was carried out in order to verify the performance of the neural network estimator. The experimental results show that the proposed neural network estimator can predict the bead width with reasonable accuracy and guarantee the uniform weld quality.

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Welding Bead Segmentation Algorithm Using Edge Enhancement and Active Contour (에지 향상과 활성 윤곽선을 이용한 용접 비드 영역화 알고리즘)

  • Mlyahilu, John N.;Kim, Jong-Nam
    • Journal of the Institute of Convergence Signal Processing
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    • v.21 no.4
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    • pp.209-215
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    • 2020
  • In this paper, we propose an algorithm for segmenting weld bead images using edge enhancement and active contours. In the proposed method, high-frequency filtering and contrast improvement are performed for edge enhancement, and then, by applying the active contour method, only the weld bead region can be obtained. The proposed algorithm detects an edge through high-frequency filtering and reinforces the detected edge by using contrast enhancement. After the edge information is improved in this way, the weld bead area can be extracted by applying the active contour method. The proposed algorithm shows better performance than the existing methods for segmenting the weld bead in the image. For the objective reliability of the proposed algorithm, it was compared with the existing high pass filtering methods, and it was confirmed that the welding bead segmentation of the proposed method is excellent. The proposed method can be usefully used in evaluating the quality of the weld bead through an additional procedure for the segmented weld bead.

Selection of Optimal Welding Condition in Root-pass Welding of V-groove Butt Joint (맞대기 V-그루브 이음 초층 용접에서 최적의 용접조건 선정)

  • Yun, Seok-Chul;Kim, Jae-Woong
    • Journal of Welding and Joining
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    • v.27 no.1
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    • pp.95-101
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    • 2009
  • In case of manufacturing the high quality welds or pipeline, the full penetration weld has to be made along the weld joint. Thus the root pass welding is very important and has to be selected carefully. In this study, an experimental method for the selection of optimal welding condition was proposed in the root pass welding which was done along the V-grooved butt weld joint. This method uses the response surface analysis in which the width and height of back bead were chosen as the quality variables of the weld. The overall desirability function, which is the combined desirability function for the two quality variables, was used as the objective function for getting the optimal welding condition. In the experiments, the target values of the back bead width and the height are 6mm and zero respectively for the V-grooved butt weld joint of 8mm thickness mild steel. The optimal welding conditions could predict the back bead profile(bead width and height) as 6.003mm and -0.003mm. From a series of welding test, it was revealed that a uniform and full penetration weld bead can be obtained by adopting the optimal welding condition which was determined according to the method proposed.

A New Algorithm for Predicting Process Variables on Welding Bead Geometry for Robotic Arc welding (로봇 아아크 용접에서 비드 형상에 공정변수들을 예측하기 위한 새로운 알고리즘)

  • 김일수
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1997.04a
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    • pp.36-41
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    • 1997
  • With the trend towards welding automation and robozation, mathematical models for studying the influence of various parameters on the weld bead geometry in Gas Metal Arc(GMA) welding process are required. The results of bead on plate welds deposited using the GMA welding process has enabled mathematical relationships to be developed that model the weld bead geometry. Experimental results were compared to outputs obtained using existing formulae that correlate process input variables to output parameters and subsequent modelling was performed in order to better predict the output of the GMA welding process. The aim of this work was to explain the relationships between GMA welding variables and weld bead geometry and thus, be able to predict input weld bead size. The relationships can be usefully employed for open loop process control and also for adaptive control provided that dynamic sensing of process output is performed.

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A Study on the Effects of the Fatigue Life due to the Processing of the Butt Weld Specimens and the Fatigue Life Estimation due to the Weld Zone Profiles (철도 구조물용 맞대기 용접시편 가공에 의한 피로수명 영향 및 용접부 형상을 이용한 피로수명 예측 연구)

  • Kim Jae-Hoon
    • Journal of the Korean Society for Railway
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    • v.9 no.4 s.35
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    • pp.371-378
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    • 2006
  • This study investigates the effects of the material properties and the fatigue behaviors in the SM490A material butt weld specimens due to the heat-treatment and the grinding. In the fatigue behavior, the heat-treatment affects the fatigue life. The S-N curves of both matrix specimen and butt weld specimen are reversed at some cycle by the existence or nonexistence of heat-treatment. The grinding on the bead makes the fatigue limit decrease in the all specimens. But the reinforcement removed, the fatigue limit increases at the high cycle. Also, this study investigates the fatigue life estimation by examining butt weld bead profiles. The butt weld beads, which are welded by semi-robot method, have non-uniform bead profiles described by $\theta,\;\rho$ and h. The stress concentration factors $K_t$, are changed by each different $\theta,\;\rho$ and h from 1.395 to 2.863. Hence, the sensitivity of $K_t$ is changed by each $\theta,\;\rho$ and h. As $\theta$ becomes lower and $\rho$ and h become higher, $K_t$ increases. The fatigue life can he estimated very closely for the AAY specimens without residual stress using only butt weld bead profiles. But, fur the AAN specimens with residual stress, the fatigue life must be estimated by considering both the weld bead profiles and the residual stress data.

The characteristic of strength weld according to patterns of weld bead on $CO_2$ laser welding ($CO_2$ 레이저 용접시 비드패턴에 따른 용접강도 특성)

  • Kim, T.I.;Song, Y.C.;Lee, M.Y.;Nam, K.W.
    • Laser Solutions
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    • v.11 no.1
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    • pp.32-35
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    • 2008
  • In the remote welding system using $CO_2$ laser, laser beam can be rapidly transferred to a workpiece by moving mirrors of scanner system. So, it makes reducing the cycle time of welding process. We can also use and apply various patterns of weld beads by linear controlled mirrors. But most of the domestic car makers have usually applied use stitch-shaped weld bead. In that case, we don't have the merit of remote welding system efficiently. Therefore, in this paper, we investigated the characteristic of weld strength according to patterns of weld bead on $CO_2$ laser welding. And we also studied the relationship between shape of weld bead and value of tensile load.

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A Study of the Thermal Analysis of Horizontal Fillet Joints by Considering the Bead Shape in GMA Welding (GMA 용접에서 비드형상을 고려한 수평필릿용접부의 온도해석에 관한 연구)

  • Jo, Si-Hun;Kim, Jae-Ung
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.8
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    • pp.71-78
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    • 2001
  • In GMA(Gas Metal Arc)Welding, the weld size that is a locally melted area of a workpiece is one of the most important considerations in determining the strength of a welded structure. Variations in the weld power and the welding heat flux may affect the weld pool formation and ultimately the size of the weld. Therefore, an accurate prediction of the weld size requires a precise analysis of the weld thermal cycle. In this study, a model which can estimate the weld bead geometry and a method for thermal analysis, including the model, are suggested. In order to analyze the weld bead geometry, a mathematical model was developed with transformed coordinates to apply to the horizontal fillet joints. A heat flow analysis was performed with a two dimensional finite element model that was adopted for computing the base metal melting zone. The reliability of the proposed model and the thermal analysis was evaluated through experiments, and the results showed that the proposed model was very effective for predicting the weld bead shape and good correspondence in melting zone of the base metal.

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A STUDY ON THERMAL ANALYSIS OF HORIZONTAL FILLET JOINTS BY CONSIDERING BEAD SHAPE IN GMA WELDING

  • Cho, Si-Hoon;Kim, Jae-Woong
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.151-155
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    • 2002
  • In GMA(Gas Metal Arc)Welding, the weld size that is a locally melted area of a workpiece is one of the most important considerations in determining the strength of a welded structure. Variations in the weld power and the welding heat flux may affect the weld pool formation and ultimately the size of the weld. Therefore, an accurate prediction of the weld size requires a precise analysis of the weld thermal cycle. In this study, a model which can estimate the weld bead geometry and a method for thermal analysis, including the model, are suggested. In order to analyze the weld bead geometry, a mathematical model was developed with transformed coordinates to apply to the horizontal fillet joints. A heat flow analysis was performed with a two dimensional finite element model that was adopted for computing the base metal melting zone. The reliability of the proposed model and the thermal analysis was evaluated through experiments, and the results showed that the proposed model was very effective for predicting the weld bead shape and good correspondence in melting zone of the base metal.

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A study on the sensitivity analysis of welding process parameters on weld bead geometry (용접 비드 형상에 대한 용접공정 변수의 민감도 해석에 관한 연구)

  • 이세환
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1998.03a
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    • pp.274-280
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    • 1998
  • The welding technology and qualities are developed significantly, in recent years, in the use of automated processing technology and welding robot systems. But these automated welding technologies have many difficulties for finding the optimal welding parameter conditions. Because of the lack of mathematical model for determination of optimal welding process parameters. In this study, the sensitivity analysis of the empirical equations for finding weld bead width, height and penetration depth by using the published formulae. The selected major welding process parameters effected to weld bead geometries are the welding speed, current, voltage and weld wire diameter.

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