• Title/Summary/Keyword: Surface Bead Width

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High power $CO_2$ laser beam welding for low carbon steels (저탄소강의 고출력 $CO_2$ 레이저 빔 용접)

  • 김재도
    • Journal of Welding and Joining
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    • v.7 no.4
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    • pp.12-21
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    • 1989
  • Laser beam welding parameters have experimentally investigated, using a continuous wave 3kW $CO_2$ laser with the various travel speeds, beam mode and laser beam power in low carbon steels. An optimum position of focus and the effect of shielding gas on penetration depth with varying the flow range of 0.5 to 5.1m/min have been combined to investigate the effect of laser power and travel speed on penetration depth and bead width. It is found that the optimum position of focus in 3kW class laser is 0.5 to 1.5mm below the surface of the material. The flow rate of shielding gas affects the penetration depth and He is more effective than Ar. The penetration depth in laser welds of low carbon steels is between two and four times of the bead width. Laser beam welding of butt joints in 2mm thick carbon steel has been carried out to establish a weldability lobe. The lobe indicating acceptable welding conditions is introduced.

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Solidification Crackin in Root Pass for One-side Welding of 590MPa Class Steel for Pressure Vessels by FCAW (FCAW에 의한 590MPa급 고장력압력용기강의 초층편면용접부에서 발생하는 고온균열)

  • 김우열;한일욱;유덕상;방한서;안용식;박화순
    • Journal of Welding and Joining
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    • v.17 no.5
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    • pp.47-54
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    • 1999
  • It is well known that solidification cracking often occurs in welds of root pass for one-side welding under the conditions of high welding currents and speeds. In this study, the solidification in 590MPa class steel for pressure vessels SPPV490 was investigated by using flux-cored arc welding(FCAW) with 4 types of welding wires and welding conditions of 200∼280A and 2.8∼ 4.2mm/sec. In order to compared the result of cracking in SPPV490, 0.2%C steel for welded structure of SWS400 and 0.45%C steel for machine structural SM45C were also used as base metals. As the results, all the cracks formed in some welding conditions were observed near the center of weld bead. The solidification cracks were generally initiated near the upper surface of bead and propagated toward the inner part. The solidification cracking generally increased with welding current and welding speed in the same base metal and welding material. In cracking susceptibility, SPPV490 showed higher cracking susceptibility than SWS400 in all welding conditions and welding materials. It was considered that cracking susceptibility could not be evaluated with the hardness of weld metals. The cracking ratio increased with decreasing of a/b(a and b; the width of the upper surface and the back surface of the bead) as shape factor of bead. The cracking tendency with shape factor of bead was extended under the condition of higher welding currents.

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An Experimental Study on Mathematical Model to Predict Bead Width in GMA Weldment (GMA 용접부의 비드폭 예측을 위한 수학적 모델에 관한 실험적 연구)

  • Kim, Ill Soo;Park, Min Ho;Kim, Hak Hyoung;Lee, Jong Pyo;Park, Cheol Kyun;Shim, Ji Yeon
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.2
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    • pp.209-217
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    • 2015
  • Generally welding is one of the most important processes to have a strong influence on the quality and productivity from a manufacture-based industry such as shipbuilding, automotive and machinery. The GMA(Gas Metal Arc) welding process involves large number of interdependent welding parameters which may affect product quality, productivity and cost effectiveness. To solve such problems, mathematical models are required to select the welding parameters for GMA welding process. In this study, the GMA welding process was studied using the information generated during the welding. The statistical analysis of a generalized regression approach was conducted by the following three methods: Firstly using the mathematical model (linear regression, 2nd regression); Secondly GA(Genetic Algorithm) with intelligent models; And finally using response surface analysis of models to develop the relationships between welding parameters and bead width as welding quality.

Weld pool size estimation of GMAW using IR temperature sensor (GMA 용접공정에서 적외선 온도 센서를 이용한 용융지 크기 예측)

  • 김병만;김영선;조형석
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.1404-1407
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    • 1996
  • A quality monitoring system in butt welding process is proposed to estimate weld pool sizes. The geometrical parameters of the weld pool such as the top bead width and the penetration depth plus half back width are utilized to prove the integrity of the weld quality. The monitoring variables used are the surface temperatures measured at three points on the top surface of the weldment. The temperature profile is assumed that it has a gaussian distribution in vertical direction of torch movement and verify this assumption through temperature analysis. A neural network estimator is designed to estimate weld pool size from temperature informations. The experimental results show that the proposed neural network estimator which used gaussian distribution as temperature information can estimate the weld pool sizes accurately than used three point temperatures as temperature information. Considering the change of gap size in butt welding, the experiment were performed on various gap size.

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Prediction of the Top-bead width of Tandem GMA Welding Processes Using the STACO Model (STACO 모델을 이용한 탄템 GMA 용접공정의 표면비드 폭 예측)

  • Lee, Jong Pyo;Park, Min Ho;Kim, Do Hyeong;Jin, Byeong Ju;Son, Joon Sik;Kang, Bong Yong;Shim, Ji Yeon;Kim, Ill Soo
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.25 no.1
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    • pp.30-35
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    • 2016
  • Tandem arc welding is a guarantor for high efficiency and cost saving since the quantity of wire which is deposited in the welding is approximated 30% greater that in conventional welding. The welding process is now being successfully applied in many industries. However, in the case of tandem arc welding, good quality and high productivity should depend on the welding parameters. Therefore, an intelligent algorithms for the automatic tandem arc welding process has been necessarily required. In this study, a predictive model based on the neural network by using the data acquired during tandem gas metal arc (GMA) welding process has been developed. To verify the reliability of the developed predictive model, a mutual comparison with the surface of the top-bead width obtained from actual experiments has been analyzed.

A Study on the Preparation and Wear Characteristics of TiC Hardfaced Layers on Aluminium alloy by PTA Method (PTA법에 의한 TiC 분말 표면강화 AL 합금층의 제조 및 마모특성에 관한 연구)

  • 민준원;유승을
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.9
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    • pp.138-145
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    • 1999
  • Surface hardening of AC4C aluminium alloy with TiC powders was obtained by plasma transferred are (PTA) method, Bead appearance, microstrucutre and wear behavior were characterized in relation to the torch current, powder feed rate and wear condition. The width and the depth of bead were mainly increased with increasing torch current. The comparison of wear behavior between AC4C alloy and PTA treated AC4C alloy showed the remarkable enhancement of wear resistance.

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Adaptive control of the back bead width in gas metal arc welding process (아크용접에서 이면비드 크기의 적응제어)

  • 부광석;조형석;오준호
    • 제어로봇시스템학회:학술대회논문집
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    • 1988.10a
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    • pp.289-294
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    • 1988
  • This paper describes tbe design and implementation of the adaptive controller to maintain the glood weld quality in gas metal arc welding process. The weld torch travel speed and the surface temperature are taken, respectively, as an input and an output of the welding control system. Because of the very complex phenomena of the process, the input-output dynamic model was experimentally identified by AIC (Akiake Information Criterion). Based on the model structure, the explicit model reference adaptive controller is simulated in order to regulate the output tempernture to the desired level.

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A study on the electrom beam weldability of 9%Ni steel (II) - Effect of $a_b$ parameter on bead shape - (9%Ni 강의 전자빔 용접성에 관한 연구 II -비이드형상에 미치는$a_b$parameter의 영향)

  • 김숙환;강정윤
    • Journal of Welding and Joining
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    • v.15 no.3
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    • pp.88-98
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    • 1997
  • Welding defects, such as porosity and spike, have sometimes occurred in deep penetration electron beam welds. These defects are known to be one of the serious problem in electron beam welds. So, effects of active parameters ($a_b$) on bead shape and occurrence of defects in electron beam welds of heavy section 9%Ni steel plates were investigated. Partial penetration welding in flat position, and deep penetration welding of 10 ~ 28mm depth were investigated in this study. It is desirable to select low accelerating voltage and above the surface focus position $a_b$$\geq$1.2 at which a wine-cup shaped bead is obtained to avoid the welding defects such as spike and root porosity. When the accelerating voltage of electron beam was low (90kV), active parameter ($a_b$) did not influence on the bead width, penetration depth and weld defects significantly. However, in case of high voltage ($\geq$120kV), active parameter ($a_b$) was sensitively associated with penetraton depth and weld defects, i.e. when the active parameter (($a_b$) was in the range of 0.6 to 1.0, the depth of penetration was always over the target (23mm), while the depth of penetration was dramatically decreased with further increase of active parameter ($a_b$). The weld defects were decreased with the increase of active parameter $a_b$ resulting in the decrease of energy density of the focused beam in the root part of fusion zone.

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Control of Weld Pool Size in GMA Welding Process Using Neural Networks (신경회로를 이용한 GMA 용접 공정에서의 용융지의 크기 제어)

  • 임태균;조형석;부광석
    • Journal of Welding and Joining
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    • v.12 no.1
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    • pp.59-72
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    • 1994
  • This paper presents an on-line quality monitoring and control method to obtain a uniform weld quality in gas metal arc welding (GMAW) processes. The geometrical parameters of the weld pool such as the top bead width and the penetration depth plus half back width are utilized to assess the integrity of the weld quality. Since a good quality weld is characterized by a relatively high depth-to-width ratio in its dimensions, the second geometrical parameter is regulated to a desired one. The monitoring variables are the surface temperatures measured at various points on the top surface of the weldment which are strongly related to the formation of the weld pool The relationship between the measured temperatures and the weld pool size is implemented on the multilayer perceptrons which are powerful for realization of complex mapping characteristics through training by samples. For on-line quality monitoring and control, it is prerequisite to estimate the weld pool sizes in the region of transient states. For this purpose, the time history of the surface temperatures is used as the input to the neural estimator. The control purpose is to obtain a uniform weld quality. In this research, the weld pool size is directly regulated to a desired one. The proposed controller is composed of a neural pool size estimator, a neural feedforward controller and a conventional feedback controller. The pool size estimator predicts the weld pool size under growing. The feedforward controller compensates for the nonlinear characteristics of the welding process. A series of simulation studies shows that the proposed control method improves the overall system response in the presence of changes in torch travel speed during GMA welding and guarantees the uniform weld quality.

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A Study on Characterization of Modified Surface Manufactured by PTA Spray (PTA 용사에 의해 제조된 표면개질부의 특성에 관한 연구)

  • Kim, Gwang-Soo;Ji, Jung-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.6 no.2
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    • pp.110-115
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    • 2005
  • Plasma Transferred Arc Spray process was used to make modified surface for wear and corrosion resistant by using Co system powder type alloy. The modified surface was produced by changing only spray current and other process variables were constant. The current range was from 80 amp to 140 amp as inclosing 20 amp. It was appeared that the geometrical shape, microstructures and microhardness of the modified surface were affected by the different cooling rate of base metal. The modified surface that produced by 120 amp current exhibited the fine microstructure and the highest microhardness number impling good surface characteristics. It was also found that the spray current affected the width but not the height of the bead as increasing current.

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