• Title/Summary/Keyword: T 형상 용접

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A Comparison study on cross and coaxial nozzle characteristic by using CW Nd:YAG Laser (연속파형 Nd:YAG 레이저 용접에서 크로스노즐과 동축노즐 특성 비교)

  • Lee, Ka Ram;Hwang, Chan Youn;Park, Eun Kyeong;Yoo, Young Tae
    • Laser Solutions
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    • v.16 no.3
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    • pp.11-21
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    • 2013
  • As parts are becoming more complex and smaller with the development of new materials, high-quality laser precision processing is getting the limelight. Laser enables quick processing and less deformation of materials. It also enables welding with diverse materials. In this study, the pole rod and tap for the secondary battery were laser-welded using cross and coaxial nozzles. The results of the comparative analysis of cross and coaxial nozzles according to the processing parameters showed that the coaxial nozzle had more sensitive welding characteristic to the nozzle position or pressure than the cross nozzle. This indicated that the processing parameters should be carefully determined for the welding with the coaxial nozzle. The pole rod and tap were welded together in a form of T joint to improve the output of the secondary battery, and the cross nozzle had a better welding characteristic than the coaxial nozzle.

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The Classification of U.T Defects in the Pressure Vessel Weld using the Pattern Recognition Analysis (형상인식을 이용한 압력용기 용접부 결함 특성 분류)

  • Shim, C.M.;Joo, Y.S.;Hong, S.S.;Jang, K.O.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.13 no.2
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    • pp.11-19
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    • 1993
  • It is very essential to get the accurate classification of defects in primary pressure vessel weld for the safety of nuclear power plant. The signal analysis using the digital signal processing and pattern recognition is performed to classify UT defects extracting feature vector from ultrasonic signals. The minimum distance classifier and the maximum likelihood classifier based on statistics were applied in this experiment to discriminate ultrasonics data obtained form both the training specimens (slit, hole) and the testing specimens(crack, slag). The classification rate was measured using pattern classifier. Results of this study show the promise in solving the many flaw classification problems that exist today.

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Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (II) - The Effect of Control of Heat Input on Weldability - (티타늄 판재의 파이버 레이저 용접시 공정변수에 따른 용접특성 (II) - 입열량 제어에 따른 영향 -)

  • Kim, Jong Do;Kim, Ji Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.12
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    • pp.1055-1060
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    • 2016
  • Laser welding is a high-density energy welding method. Hence, deep penetration and high welding speed can be realized with lower heat input as compared with conventional welding. The heat input of a CW laser welding is determined by laser power and welding speed. In this study, bead and lap welding of $0.5mm^t$ pure titanium was performed using a fiber laser. Its weldability with laser power and welding speed was evaluated. Penetration, bead width, joining length, and bead shape were investigated, and the mechanical properties were examined through tensile-shear strength tests. Welds with sound joining length were obtained when the laser power and welding speed were respectively 0.5 kW and 2.5 m/min, and 1.5 kW and 6 m/min, and the weld obtained at low output presented better ductility than that obtained at high output.

Effects of Geometry of Reactor Pressure Vessel Upper Head Control Rod Drive Mechanism Penetration Nozzles on J-Groove Weld Residual Stress (원자로 상부헤드 제어봉구동장치 관통노즐 형상이 J-Groove 용접잔류응력에 미치는 영향)

  • Kim, Ju-Hee;Kim, Yun-Jae;Lee, Sung-Ho;Hur, Nam-Young;Bae, Hong-Yeol;Oh, Chang-Young;Kim, Ji-Soo;Park, Heung-Bae;Lee, Seung-Geon;Kim, Jong-Sung;Huh, Nam-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.10
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    • pp.1337-1345
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    • 2011
  • In pressurized water reactors (PWRs), the reactor pressure vessel (RPV) upper head contains numerous control rod drive mechanism (CRDM) nozzles. In the last 10 years, the incidences of cracking in alloy 600 CRDM nozzles and their associated welds has increased significantly. Several axial and circumferential cracks have been found in CRDM nozzles in European PWRs and U.S. nuclear power plants. These cracks are caused by primary water stress corrosion cracking (PWSCC) and have been shown to be driven by welding residual stresses and operational stresses in the weld region. Therefore, detailed finite-element (FE) simulations for the Korea Nuclear Reactor Pressure Vessel have been conducted in order to predict the magnitudes of the weld residual stresses in the tube materials. In particular, the weld residual stress results are compared in terms for nozzle location, geometry factor$r_o$/t, geometry of fillet, and adjacent nozzle.

Friction Welding Analysis of Welding Part Shape with Flow Gallery by Friction Welding (마찰용접에 의해 유동부를 갖는 용접부 형상의 마찰용접해석)

  • Yeom S. H.;Nam K. O.;Yoo Y. S.;Hong S. I.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.109-112
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    • 2005
  • Friction welding is welding method to use frictional heat of two material. A defect of friction welding is that create flash. The flash is part that must have cut after welding finished. But the welding part with flow gallery by friction welding can't cut flash. Therefore the welding part with flow gallery was designed with no effect in flow. In this research, decide the welding shape parameter of welding part with flow gallery and do friction welding analysis. In friction welding analysis, must input necessary S-S curve, friction coefficient by temperature change, upset pressure, RPM etc. According to analysis result, decided the optimal shape of welding part with no effect in flow.

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Role of Post Weld Treatment Methods in the Improvement of Fatigue Life for T-type Welded Structures Made by SM 50A Steel (SM 50A 강으로 제작된 T-형 용접형상의 용접후처리 방법이 피로수명 증가에 작용하는 역할)

  • Han, Chang-Wan;Lee, Jae-Hoon;Song, Jun-Hyouk;Lee, Hyun-Woo;Park, Seong-Hun
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.3
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    • pp.307-312
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    • 2012
  • This study aims to investigate the effect of the post weld treatments on the fatigue life of T-type welded structure made by a SM50A steel material, generally used for excavators, because changes in the geometry, material and surface properties of welded regions affect the fatigue life of welded structures. T-type test specimens were prepared by the CO2 welding of rolled steel plates (SM50A steel) with a thickness of 10 mm at a welding speed of 30 cm/min and these Ttype welded specimens were further treated by UIT (Ultrasonic Impact Treatment) and/or toegrinding post welding treatment methods. In order to investigate improvements on the fatigue life of the samples. 3-point bending fatigue tests were conducted with a stress ratio of R=0.1 under a cyclic loading environment at a frequency of 5 Hz, via a hydraulic fatigue testing machine (${\pm}100\;kN$, MTS 809). The tests were performed at room temperature. The fatigue life of UIT specimens was approximately 25 times longer than that of as-welded specimens at a stress amplitude of 281 MPa, while toe-grinding specimens exhibited 4.15 times longer fatigue life. The current results could provide important guidelines to determine the proper post weld treatment methodologies of T-type welded parts for excavators with a satisfactory fatigue life although under severe operating conditions.

A Study on the Mechanical Mechanism According to the Groove Shape of T-welded Joint (T-joint 용접부의 형상에 따른 역학적 메카니즘에 관한 연구)

  • 방한서;김종명
    • Journal of Welding and Joining
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    • v.17 no.6
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    • pp.53-61
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    • 1999
  • The use of thick plate in increasing in recent years due to the rapid expansion of chemical plants, nuclear plants, ships and other industrial plants. Welding is the most popular joining techniques employed in manufacturing industrial machineries and structures. Normally, Groove shapes are prepared according to appropriate rules and regulations such as KS, JIS, AWS, LR, DNV and etc. for various thicknesses of plate. However those groove angles tend to be too large. As a result of large groove angle, residual stress, deformation of material and strength reduction is obtained. Therefore, the reliability and safety of structures and machinery tend to be decreasing. Therefore, in this paper, theoretical as well as experimental study are carried out to find optimum groove shapes for T-welded joint of mild steel. The test specimen are made in same condition with simulation model. Welding residual stresses measurement by sectional cutting method. ⅰ) The mechanical difference for change the thickness of plate and groove angle are not appeared. ⅱ) In a mechanical point of view minimum preparation angle(40°) is more suitable than maximum groove angle(60℃). ⅲ) The measurement value and distribution of welding residual stresses are not effected largely by groove angle. It is mechanical restraint that mainly affect welding residual stresses distribution. In mechanical point of view minimum groove angle is more suitable than maximum groove angle. Therefore, it is appropriate to minimize the size of groove shape in strength and safety.

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Modeling Scheme for Weld-Jointed Parts for Precise Structural Analysis of Large-Scale Structures (대형구조물의 구조해석 정밀도 향상을 위한 용접부 모델링 기법)

  • Jin, Dawei;Park, Sang-Hu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.10
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    • pp.1195-1203
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    • 2012
  • Welding is a well-developed, widely used process for permanently joining metal components. However, the mechanical reliability of welded parts still offers room for improvement. A weld region consists of a fusion zone, a partially melted zone, and a heat-affected zone, and each zone has different material properties. In addition, the geometrical shape of a weld bead or fillet influences the mechanical reliability. A precise structural analysis must consider how a local welded region influences the mechanical behavior of the entire structure. This study focuses on an effective modeling scheme for the weld region. It relies on experimental and numerical methods to determine the proper correlation based on experimental results and to propose a modeling scheme for welded parts.

Evaluating Seismic Performance of Steel Welded Moment Connections Fabricated with SN Steel (SN 강재가 사용된 강구조 용접모멘트접합부의 내진성능 평가)

  • Oh, Sang-Hoon;Choi, Young-Jae;Yoon, Sung-Kee;Lee, Dong-Gue
    • Journal of Korean Society of Steel Construction
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    • v.22 no.3
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    • pp.271-280
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    • 2010
  • This study was programmed to fabricate a beam-to-column connection that is limited to a steel-welded moment connection with full-scale members, using SN steel. A cyclic seismic test was conducted of the nine specimens that were fabricated by choosing the test variable for the weld access hole geometry, connection design method, and RBS. From the test results, failure modes, the moment-drift behavior, and the strain distribution were provided. From the specimen material properties, the beam's nominal plastic flexural capacity and classified qualified connection as a special moment flame were calculated. By analyzing the skeleton part and the baushinger part, a range of strength-raising effects, and deformation ratios were provided, with which the seismic performance of the specimens were evaluated. The test results showed that the specimens eliminated their weld access holes that demonstrated higher seismic performance than the specimens' existing weld access holes, and that the WUF-W connection that was reinforced by the supplemental fillet weld around the shear tap that was fastened by five bolts demonstrated superior seismic performance.

Manufacturing Ti-Alloy Frames of Classes with High-Precision Laser Beam Welding (초정밀 레이저용접을 이용한 티타늄 안경테 제조)

  • 황용화;김수성;이형권;민덕기;고진현
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.1 no.2
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    • pp.1-8
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    • 2000
  • An attempt was made to develop commercially pure titanium frames of glasses with a high-precision laser beam welding machine, in which a resonator with 12kw of the peak power and 200 W of maximum mean power has the capacity of variable in the range of 0.08~10 ms pulse width. In addition the optical fiber beam transmission with 400 ${\mu}{\textrm}{m}$ of the core diameter and a weld chamber to contain specimens in the inert gas atmosphere were also designed and used. In the present study. titanium frames of glasses parts such as temple plus spring hinge. bridge and top bar were experimentally manufactured by utilizing the optimum welding parameters with the optical fiber of GI 400 ${\mu}{\textrm}{m}$, 2.9J energy per pulse, and focussing position for Tee and butt joints. The titanium welded joints with laser beam welding did not reveal any severe weld defects or weld bead appearance except some pores in the weld section.

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