• Title/Summary/Keyword: 레이저 용접

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A Study on In-process Measurement in Laser Welding of Primer-coated Steel for Shipbuilding (II) -Defect Detection with Coating Condition and Gap Clearance- (조선용 프라이머 코팅 강판의 레이저용접시 인프로세스 측정에 관한 연구 (II) -코팅조건과 갭간극에 따른 불량검출-)

  • Kim, Jong-Do;Lee, Chang-Je;Lee, Jae-Bum;Hong, Seung-Gab;Park, Hyun-Jun
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.115-115
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    • 2009
  • 아연코팅강판의 레이저 용접시 발생하는 용접결함은 이미 널리 알려진 이슈이다. 그러나 대부분의 연구가 박판을 중심으로 이루어지고 있어서, 후판을 중심으로 한 조선산업에서의 아연코팅 강판의 연구는 매우 미진한 실정이다. 이중 후판 아연코팅강판의 결함검출연구는 그 연구가 거의 전무한 실정으로, 본 연구에서는 후판 아연코팅강판의 레이저 겹치기용접시의 결함검출을 중심으로 실험을 실시하였다. 실험은 Fig. 1에서와 같이 광신호와 음향신호의 RMS를 통하여 raw signal에서 잘 나타나지 않았던 신호의 패턴을 확인함으로써 실제 신호와 비드와를 대응을 가능하게 하였다. 또한 결함 발생시의 RMS값을 건전한 상태와 비교분석하여 실제 결함검출의 가능성도 확인할 수 있었다.

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Characteristics of Plasma Emission Signals in Fiber Laser Welding of API Steel (III) -The Effect on Plasma Emission Signals by Shield Gas- (API강재의 파이버레이저 용접시 유기하는 플라즈마의 방사특성 (III) - 보호가스가 플라즈마 방사 신호에 미치는 영향 -)

  • Lee, Chang-Je;Kim, Jong-Do;Kim, Yu-Chan
    • Journal of Welding and Joining
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    • v.31 no.3
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    • pp.60-65
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    • 2013
  • Ar, $N_2$, and He are the conventional kind of shield gas that are used for laser welding. Many researches on the impact of laser welding shield gas have been done, and it is on going until now. However, there are few studies that analyze the changes and differences of the plasma emission signal. Therefore, in this study, we evaluated the change in the penetration characteristics according to the type of shield gas during fiber laser welding impacts to the plasma signal. As a result, if was checked that the difference in molecular weight of Ar, $N_2$, and He affects to the amount of spatter, and also found that the measured plasma radiation signal changes similar to the order of the molecular weight of the gases. Especially, clear change on the signal intensity per each shield gas was measured through RMS, and found that the shield gas was nothing to do with the FFT analyzed result.

Evaluation of the Stress Occurring Phenomenon for Cold-Rolled Carbon Steel During a Laser Welding Process (냉연 압연 강판의 레이저 용접 공정 시 발생하는 응력 평가)

  • Lee, Chulku;Lee, Wooram
    • Journal of Welding and Joining
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    • v.31 no.1
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    • pp.51-57
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    • 2013
  • Residual stress caused in the weldments with high restraint force are often observed during welding in the weldments of Inner and outdoor materials or radial tanks. The reason is that quantitative analysis about thermal stresses during laser welding is lacking for this weldments. To verify Finite Elements Method (FEM) theory, the temperature was measured with thermocouple in a real time in this paper. Also analysis of the thermal stress for welding condition is performed by Comsol program package on various welding condition in SCP1-S butt welding. The principal stress in laser welding process is seen through the width direction. Also, it was confirmed that a change in base metal by thermal expansion made the stress in width direction stronger. Base metal close to the weld bead as the process progresses to the tensile stress in the compressive stress was varied. It was shown that the change of stress was quantitative from the bead at a certain distance.

A Effects of Magnetic Field For Fiber Laser Micro Welding Process Using Carbon Steel of SCP1-S (자기장 영향에 따른 냉연압연 강판의 파이버 레이저 마이크로 접합 공정)

  • Lee, C.K.;Lee, W.R.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.3
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    • pp.433-438
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    • 2012
  • We have studied on welding dissimilar materials of Carbon steel SCP1-S by using laser beam. In this research we have performed some experiments to know the possibility of welding dissimilar materials using laser beam and magnetic fields by adjusting the power output of 35W laser. Other conditions of the experiments were as follows : the welding speed was varied in the range 10 m/min nitrogen gas was used as shield gas, the flow value of shield gas was ranged 10 L/min. In order to ascertain of the welded surface, we have done the tensile strength testing, the hardness testing and the microscope observation. As a result, we have found that tensile strength was the highest at the condition of the welding speed of 10mm/s, the flow value of 10 L/min, the gap of two materials 0, and the use of nitrogen gas. Above testings have also showed that the tensile strength was generally satisfactory since the penetration of welding was almost complete due to the thinness of the materials. In addition, the formation of the welded area was excellent when it had the highest tensile strength.

Effects of Different Shielding Gases in Laser Welding of Secondary Ni battery with Multi-thin Plates (이차전지용 니켈 다층 박판의 레이저 용접 보호가스의 영향)

  • You, Young-Tae;Lee, Ka-Ram;Kim, Jin-Woo
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.25 no.5
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    • pp.329-337
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    • 2016
  • The demand for the eco-friendly vehicles is skyrocketing because of the increasing $CO_2$ emissions and global warming. In the industrial field, the battery process, a core part of an eco-friendly vehicle, is drawing increased attention; its weight lightening as well as high energy density are becoming increasingly important. In this study, pure Ni plates that were used as the battery pole plate were welded using the laser. The lab joint welding was conducted on ten pure Ni plates at a laser power of 1900 W and a feed speed of 2.8-3.4 m/min. As observed in the experiment, a faster feed speed reduced the bead width, but the laser did not penetrate all ten specimen plates. In addition, pores were trapped when protective gas was used, but they were not trapped when the welding was conducted in atmospheric condition.

Finite element analysis for prediction of weld bead shape of Nd:YAG pulse laser welding for AISI 304 stainless steel plate (AISI 304 스테인리스 강판의 Nd:YAG 펄스 레이저 용접비드 형상예측을 위한 유한요소해석)

  • Cho Haeyong;Kim Kwanwoo;Hong Jinuk;Lee Jaehoon;Suh Jeong
    • Laser Solutions
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    • v.8 no.1
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    • pp.19-25
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    • 2005
  • Pulse laser welding of AISI 304 stainless steel plate was simulated to optimize welding conditions by using commercial finite element code MARC. Due to geometric symmetry, a half model of AISI 304 stainless steel plate was considered. for the heat transfer analysis, user subroutines were applied to boundary condition. The material properties such as conductivity, specific heat, and mass density were given as a function of temperature and the latent heat associated with a given temperature range was considered. A moving heat source was designed on the basis of experimental data. As a result, Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

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Lab Weldability of Pure Titanium by Nd:YAG Laser (Nd:YAG 레이저를 이용한 순티타늄판의 겹치기 용접성)

  • Kim, Jong-Do;Kwak, Myung-Sub
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.2
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    • pp.315-322
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    • 2008
  • Titanium and its alloys have excellent corrosion resistance, high strength to weight ratios and creep properties in high temperature, which make them using many various fields of application. Especially, pure titanium, which has outstanding resistance for the stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion, brings out to the best material for the heat exchanger, ballast tank, desalination facilities, and so on. Responding to these needs, welding processes for titanium are also being used GTAW, GMAW, PAW, EBW, LBW, resistance welding and diffusion bonding, etc. However, titanium is very active and highly susceptible to embrittlement by oxygen, nitrogen, hydrogen and carbon at high temperature, so it needs to shield the weld metal from the air and these gases during welding by non-active gas. In this study, it was possible to get sound beads without humping and spatter with a decrease of peak power according to increase of pulse width, change of welding speed and overlap rate for heat input control, and shield conditions at pulsed laser welding of titanium plates for Lap welding.

The Fatigue Behavior of Tailored Welded Blank Sheet Metal by Laser Beam (레이저를 이용한 Tailored Blank 용접 판재의 피로거동)

  • 오택열
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.4
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    • pp.48-55
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    • 2000
  • For the Tailor Welded Blank sheet used for automobile body panel, the characteristics of fatigue strength and crack propagation behavior were studied. The thickness of specimens was joined to be same (0.9mm+0.9mm) and different (0.9mm+2.0mm) .As a base test, mechanical properties around weld zone were examined . The results indicated that there were no significant decreases in mechanical properties , but hardness around weld bead was 2.3 times greater than base material . The fatigue strength was the highest when the loading direction was parallel to the welding direction, which was about 85% of tensile strength of base material. It was decreased by 8.5% when the thickness of specimens and base metal was different, and it was increased by 25% when pres-strain was applied. The crack propagation rate was noticeably decreased around weld line and rapidly increased as it passed through weld line. Reviewing the shape of the crack propagation , crack width around weld line was around the weld zone due to retardation of crack growth , but is became narrow passing weld line due to decreased toughness.

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Process Parameters of Butt Welding of SM45C using a Continuous Wave Nd:YAG Laser Beam (연속파형 Nd:YAG 레이저를 이용한 SM45C 맞대기 용접의 공정 변수)

  • 유영태;노경보;오용석;김종신;임기건
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.7
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    • pp.44-55
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    • 2003
  • The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power. Optical microscope and SEM were used to investigate the microstructures of the welded zone. The experimental results showed that penetration depth of the welding process increases with laser power. Both the microstructural investigation and the theoretical calculations indicated that materials undergoes a very high heating and cooling cycle during welding process. It was also found that the austenite nucleation takes place at the initial stage and the completion temperature of austenite transformation is much higher than in the case of the arc welding.

Development of Plasma Monitoring System for Laser Welding Quality Analysis (레이저 용접품질 해석용 플라즈마 감시장치 개발)

  • 권장우;권오상;장영건;이경돈;홍승홍
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.05a
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    • pp.425-431
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    • 1999
  • We develope plasma monitoring system which detect plasma signals and store them for Laser welding quality evaluation and analysis using photo detector. The most fundamental and important aspects in such a system are signal restoration fidelity, noise immunity and noise cancelation capability. In this paper, we propose implementation method using distribute processing structure and hybrid digital communication for high noise cancelation capability, immunity and signal fidelity which are poorly presented in other researches. Lab experimental results and welding experimental results show a effectiveness of proposed method and plasma data is stored with 256 kbps without any communication error. we are implementing various welding defect recognition algorithm in this system.

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