• Title/Summary/Keyword: Fillet Welding

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Evaluation of Influence on the Fatigue Strength of Residual Stresses at the Welded Toe of Welded Structure. (용접구조물 요접토우부의 잔류응력이 피로강도에 미치는 영향 평가)

  • 차용훈;김하식;김일수;성백섭
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.4
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    • pp.7-13
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    • 2001
  • This Study is to investigate the influence of weld residual stresses on the fatigue crack growth behaviors in pressure ves-sel reinforcement. In order to perform this study, the automatically welded specimens are prepared. The material is ASTM A516 grade 60 steel used in pressure vessel mainly. For pad-on-plate of skip welding continuous welding and PWHT specimen, fatigue crack initiation is generally initiat-ed at weld starting and end toe zone, and ruptured at weld starting toe zone, Fatigue life if pad-on-plate continuous speci-men is increased more than that of pad-on-plate skip fillet welding specimene about 85% under low load, about 20% under high load, and decreased than that of two-pad continuous welding specimen about 85%. In da/dN-$\Delta$ Κ curve under low load, pad-on-plate skip fillet welding specimen showed retardation on the initial crack, and the fatigue crack growth rate at the low region of $\Delta$Κ greater specimene E(3.8{\times}10^{-6}$mm/cycle). And the fatigue life of welding specimen was smaller than that of PWHT specimen.

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A study on the seam tracking in CO_2$ fillet welding by using an arc sensor (CO_2$ 용접에서 전기적인 아크신호를 이용한 수평 필릿 용접선 추적에 관한 연구)

  • 선채규;김재웅;나석주;조형석;최칠룡
    • Journal of Welding and Joining
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    • v.8 no.3
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    • pp.70-78
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    • 1990
  • The harsh nature of welding environments makes welding a prime candidate for process automation. Among the variety of welding processes available, gas metal arc welding is one of the most frequently used methods, primarily because it is highly suited to a wide range of applications, and also to automation. Automatic seam tracking method is one of the most demanded techniques for automatic control of arc welding. In this study a seam tracking system has been developed by using the welding arc itself as a sensor. This paper described the principle and experimental result of the arc sensor system, as well as the development and application of the automatic CO_2$ welding for the horizontal fillet welding. A basic problem in horizontal fillet welding is the prevention of hanging bead formation such as undercut at the vertical plate and overlap at the horizontal plate. To produce the symmetric bead shape, the relationship of bead shape to welding parameters(welding velocity, weaving width, weaving speed, tip to workpiece distance) was also investigated.

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Development of a High Speed Rotating Arc Sensor System for Tracking Complicate Curved Fillet Welding Lines

  • Lee, Gun-You;Oh, Myung-Suck;Kim, Sang-Bong
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.6
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    • pp.20-28
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    • 2003
  • This paper presents development of a high speed rotating arc sensor system using a microprocessor based controller with tracking function for a complicate curved fillet welding line, The welding tip connected to the torch body is eccentrically positioned from the centerline of the torch, The area during one rotating cycle is divided into 4 regions of front, rear, right and left in welding direction of the torch tip to determine the horizontal deviation between the welding seam and the torch position. The average value at each region is calculated using the regional current values and a low pass filter incorporated with the moving average method is implemented. The effectiveness of the developed system is proven through the experimental results for several kinds of complicate curved fillet welding lines.

Deformation Characteristics of Intermittent Fillet Welding (단속 필렛 용접의 변형 특성에 관한 연구)

  • Lee, Joo-Sung
    • Journal of Ocean Engineering and Technology
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    • v.25 no.6
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    • pp.105-109
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    • 2011
  • As is well appreciated, welding is the most important fundamental process in manufacturing marine structures. However, weld-induced deformation is inevitable because of the non-uniform distribution of temperature during welding. The deformation caused by welding is one of the principal obstacles in enhancing the productivity in the manufacturing procedure for marine structures. This should be much more seriously considered in the case of the thin blocks found in a ship with multi-deck structures. This paper is concerned with the deformation control of thin panel blocks by applying intermittent welding to fillet welding. In order to investigate the quantitative effect of the intermittent welding, a thermo elasto-plastic analysis was carried out with various welding pitches and plate thicknesses. Welding tests were also carried out to show the validity of the present thermo-elasto-plastic analysis. Numerical analysis results showed good agreement with those of the welding tests. As far as the present numerical results are concerned, it has been seen that a more than 50% reduction in angular distortion can be achieved by applying the intermittent welding because of the low heat input.

Verification of Validity of Governing Factors in High Accurate Prediction of Welding Distortion (용접변형의 고정도 예측을 위한 지배인자의 정당성 검증)

  • Lee, Jae-Yik;Chang, Kyong-Ho;Kim, You-Chul
    • Journal of Welding and Joining
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    • v.31 no.5
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    • pp.7-14
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    • 2013
  • The legitimacy of dominating factor in the high accuracy prediction of welding distortion was investigated for butt welding and fillet welding. When out-of-plane distortion was measured by the experiment objecting to butt welding, if tack welding was easily performed, the position of a neutral axis was variously changed by the irregularity. Then, there have been a case that out-of-plane distortion was generated in the unexpected direction. This case should be especially noted. New model for the experiment was proposed so as to solve this problem. As it was elucidated by the case of fillet welding, it was verified that the analysis should be carried out with satisfying the yield condition (especially at high temperature above 700 degree Celsius) and with closely simulating the penetration shape (heat input in weld metal) in order to solve the proposition that is the high accuracy prediction of welding distortion. It was confirmed that residual stress is highly predicted because welding distortion is highly predicted, too.

A Study on Signal Processing Method for Welding Current in Automatic Weld Seam Tracking System (용접선 자동추적시 용접전류 신호처리 기법에 관한 연구)

  • 문형순;나석주
    • Journal of Welding and Joining
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    • v.16 no.3
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    • pp.102-110
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    • 1998
  • The horizontal fillet welding is prevalently used in heavy and ship building industries to fabricate the large scale structures. A deep understanding of the horizontal fillet welding process is restricted, because the phenomena occurring in welding are very complex and highly non-linear characteristics. To achieve the satisfactory weld bead geometry in robot welding system, the seam tracking algorithm should be reliable. The number of seam tracker was developed for arc welding automation by now. Among these seam tracker, the arc sensor is prevalently used in industrial robot welding system because of its low cost and flexibility. However, the accuracy of arc sensor would be decreased due to the electrical noise and metal transfer. In this study, the signal processing algorithm based on the neural network was implemented to enhance the reliability of measured welding current signals. Moreover, the seam tracking algorithm in conjunction with the signal processing algorithm was implemented to trace the center of weld line. It was revealed that the neural network could be effectively used to predict the welding current signal at the end of weaving.

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A Study on the Buckling in Fillet Welds of Sheets (박판 필릿용접구조물의 좌굴변형에 관한 연구)

  • Chu, Hwan-Su;Cho, Sang-Myung
    • Journal of Welding and Joining
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    • v.27 no.3
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    • pp.60-66
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    • 2009
  • The structures distorted by welding have to be corrected. Since the correcting work needs a lot of costs and time, it is very important to minimize the buckling distortion due to welding of thin plate structure. Therefore the aim of this study is to investigate the effect of single bead on plate welding and fillet welding on the buckling distortion. In the single bead on plate welding, it was found that the welding speed and welding sequence were the most dominant factors on distortion. In the fillet welding, there were four typical buckling modes observed, and the welding sequence was the most influential factor on the buckling distortion. However typical distortion measuring method is not considered for the distortion correcting process costs of each buckling modes, therefore, in this study, the measuring method is developed to classify the buckling modes for torsion of specimen and buckling distortion depend on nodal point for the bead on plate welding specimen and fillet welds.

Simplified welding distortion analysis for fillet welding using composite shell elements

  • Kim, Mingyu;Kang, Minseok;Chung, Hyun
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.3
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    • pp.452-465
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    • 2015
  • This paper presents the simplified welding distortion analysis method to predict the welding deformation of both plate and stiffener in fillet welds. Currently, the methods based on equivalent thermal strain like Strain as Direct Boundary (SDB) has been widely used due to effective prediction of welding deformation. Regarding the fillet welding, however, those methods cannot represent deformation of both members at once since the temperature degree of freedom is shared at the intersection nodes in both members. In this paper, we propose new approach to simulate deformation of both members. The method can simulate fillet weld deformations by employing composite shell element and using different thermal expansion coefficients according to thickness direction with fixed temperature at intersection nodes. For verification purpose, we compare of result from experiments, 3D thermo elastic plastic analysis, SDB method and proposed method. Compared of experiments results, the proposed method can effectively predict welding deformation for fillet welds.

Evaluation of Mechanical Test Characteristics of Fillet Welding (필릿 용접의 기계적 시험 특성 평가)

  • Cho, Byung-Jun;Lee, Soung-Jun;Rhim, Jong-Guk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.2
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    • pp.535-541
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    • 2020
  • FCAW is used mainly in the welding of carbon steel and alloy steel because it can be welded in all positions and can obtain excellent quality at sites with variable working conditions. Recently, many studies in Korea have estimated the fatigue strength, residual stress, and deformation, and to develop a fillet welding process. On the other hand, there have been few studies of the mechanical properties based on the strength, macro and magnetic particle test results for fillet welding. This study shows the following results through fillet welding, macro testing and strength testing using SM490A (solid-structure rolled steel) for thick plates using SS400 (rolled steel) for the upper plate and FCAW. The hardness test, macro test and magnetic particle test were then conducted. The hardness tests showed that all result values were smaller than the KS B 0893 standard values of 350Hv. The macro-test showed that each type of welded part was in a normal organic state and that there were no internal errors, bubbles, or impurities on the front of the welded part. Therefore, there were no concerns about lamination. The magnetic particle examination showed no problems.