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팁 선단에 중공이 있는 전극을 이용한 스패터 저감 스폿 용접에 관한 연구
전정상,이세헌,Jun, Jung-Sang,Rhee, Se-Hun 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.4
In automotive company, a lot of researchers have investigated for the spatterless welding process during last two decades. A spatter influences on the product quality such as strength and surface states. In this paper, a hollow tip is proposed for spatterless process. An optimal size of electrode hole is obtained from a weldability evaluation of each hole diameter. Through the cross section analysis, a phenomenon that molten metal moves in the hole which located between two workpiece is observed, and this makes spatterless welding process even though current is higher. Finally, widely acceptable weld area in lobe curve is obtained by using hollow tip as compare with conventional no hollow tip. In this paper, spatterless resistance spot welding with improvement weldability and productivity is proposed by using hollow tip.
DC 인버터 저항 스폿 용접에서 후전류 효과에 관한 연구
이희준,이세헌,Lee, Hui-Jun,Rhee, Se-Hun 한국생산제조학회 2009 한국생산제조학회지 Vol.25 No.2
Resistance spot welding has been investigated to apply for manufacturing car bodies because of its high productivity. So quality of resistance spot weld is one of the major concerns for both automobile and aerospace industry. Current design trends in automotive manufacture have shifted emphasis to alternative lightweight materials in order to aid in producing vehicles with higher fuel efficiency and lower down the vehicle emission level for environmental control. There is increasing emphasis to provide lighter cars. Therefore there is an effort to use high strength steels such as HSLA, dual phase, in car body. However there is used in restricted because of difficulty in producing consistently high quality resistance spot welds. In this study, resistance spot welding schedules were developed to achieve acceptable welds with improved static mechanical properties. Improved resistance spot welding schedules were developed using post heating current to reduce the cooling rate, or in-process tempering to reduce the hardness of the weld produced. The effects of resistance spot welding process parameter on hardening fracture mode and static mechanical properties of the joints were determined.
허동운,이세헌,Huh, Dong-Woon,Rhee, Se-Hun 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.5
Stainless steels are alloy steels with a nominal chromium content of at least 11 percent, with other alloy additions. The stainlessness and corrosion resistance of these alloy steels are attributed to the presence of a passive oxide film on the surface. When exposed to conditions like Resistance Spot Welding (RSW) process that remove the passive oxide film, stainless steels are subject to corrosive attack. And exposure to elevated temperatures causes oxidation (discoloration) of areas around indentation in Spot welding. In this paper, deal with the effect of shielding gas (Ar) preventing the corrosion, oxidation of stainless steel. And find the optimal shielding gas flow rate. In addition, suggest effective purging method for direct/indirect spot welding process.
자동차 차체 적용을 위한 레이저-아크 하이브리드 용접의 동축 모니터링 시스템 개발
박영환,이세헌,김철희,Park, Young-Whan,Rhee, Se-Hun,Kim, Cheol-Hee 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.6
In this paper, the coaxial monitoring system to capture image of weld pool was developed in laser-arc hybrid welding. In order to obtain the reliable image, green laser was used as a illumination system and measuring components such as band pass filter, ND (Neutral Density) filter and shutter speed was designed and optimized. Using this monitoring system, weld pool images were captured according to laser power, welding speed, welding current and interspace between laser and arc through the experiment. ANOVA (Analysis of Variation) was carried out to identify the influence of process variables on bead widths extracted from captured images of monitoring system. Welding speed and current were major factor to affect weld pool.
서보건 이용 시 저항 점 용접의 동특성 분석에 관한 연구
백정엽,이종구,이세헌,Baek Jung-Yeub,Lee Jong-Gu,Rhee Se-Hun 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.3
Air gun has been one of the good tools to press two sheet metals. However, it is not easy to control the acting force precisely. A Servo-gun is a good tool to control the acting force on the workpiece comparing with the air gun. Servo-gun has a higher tensile shear strength and lower indentation depth as well as smaller spatter. Dynamic resistance was obtained according to the acting force and welding current. As the acting force was changed during welding, the welding quality was increased.
Computer simulation for seam tracking algorithm using laser vision sensor in robotic welding
정택민,성기은,이세헌,Jung, Taik-Min,Sung, Ki-Eun,Rhee, Se-Hun Korean Society of Laser Processing 2010 한국레이저가공학회지 Vol.13 No.2
It is very important to track a complicate weld seam for the welding automation. Very recently, laser vision sensor becomes a useful sensing tool to find the seams. Until now, however studies of welding automation using a laser vision sensor, focused on either image processing or feature recognition from CCD camera. Even though it is possible to use a simple algorithm for tracking a simple seam, it is extremely difficult to develop a seam-tracking algorithm when the seam is more complex. To overcome these difficulties, this study introduces a simulation system to develop the seam tracking algorithm. This method was verified experimentally to reduce the time and effort to develop the seam tracking algorithm, and to implement the sensing device.
예비전류를 이용한 자동차용 프리실드 강판의 저항 점 용접성 향상에 관한 연구
박태규,윤상만,이세헌,Park, Tae-Gyu,Yun, Sang-Man,Rhee, Se-Hun 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.6
In the present day, new performances are demanded for automobile body steel sheet for example, light weight, durability, resistance corrosion and environmental protection. For an improvement of resistance corrosion, European automobile companies developed pre-sealed steel in 1990's. Pre-sealed steel have organic coated layer upper zinc coated layer. Evaluating a resistance spot weldability of pre-sealed steel plate is important because resistance spot welding is used mainly in automobile body joining process. In this study, evaluating a weldability of pre-sealed steel plate was carried out using lobe diagram, dynamic resistance and high-speed image. Usually, Pre-sealed steel has poor weldability than GA steel's. To improve a weldability of pre-sealed steel sheet, pre-current was applied to welding process. Pre-current is applied prior to base-current. In conclusion, the weldability of pre-sealed steel has been improved than GA steel's by applying pre-current.
저항 점 용접 로봇에서 서보건의 가압력 제어를 통한 용접 강도 향상에 대한 연구
박영환,이종구,이세헌,Park, Young-Whan,Lee, Jong-Gu,Rhee, Se-Hun 대한용접접합학회 2006 대한용접·접합학회지 Vol.24 No.6
Resistance spot welding is widely used for joining sheet metals in the automotive manufacturing process. Recently, servo-gun is used to increase the productivity and precise control the acting force. However, force control mechanisms have not been investigated with servo-guns until now. In this paper, it is proved that servo-motor current is proportional to torque and by experiment, experimental equation between servo-motor current and electrode force was derived. Algorithm for feedback control of electrode force was suggested using current measurement. In addition, applying soft touch method to this system the impact between electrode and specimen, which is the problem of air gun, could be reduced. Indentation made the force decrease in holding time of resistance spot welding. In order to overcome this problem, force compensation using the servo gun was used and it improved weld strength in good welding current range.
유전알고리즘을 이용한 인버터 DC 저항점용접에서의 정전류퍼지제어기 최적화
유지영,윤상만,이세헌,Yu, Ji-Young,Yun, Sang-Man,Rhee, Se-Hun 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.5
Inverter DC resistance spot welding process has been very widely used for joining such as automotive body sheet metal. Because the lobe area of DC welding is larger than AC welding and DC welding has low electrode wear. So the use of Inverter DC resistance spot welding process has been further increased. And the application of high tensile steel is growing for light weight vehicle. To improve the weldability of high strength steel, the development of Inverter DC resistance spot welding system is more conducted. However, Inverter DC resistance spot welding system has a few problems. Current waveform is unstable and the expulsion has been occurred by characteristics of steel. In this study, inverter DC resistance spot welding system was made. And Fuzzy control algorithm was applied for constant current. The genetic algorithm was applied to optimize the fuzzy scaling factors, in order to optimize the fuzzy control.
로브곡선을 이용한 자동차용 신강재의 저항 점 용접성 평가 기술 개발
김태형,이동옥,이세헌,Kim, Tae-Hyung,Lee, Dong-Ock,Rhee, Se-Hun 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.4
The resistance spot welding is one of the most commonly used welding process for joining the sheet metal in automotive manufacturing process due to higher deposition rates and higher economy achieved. Control variables in the resistance spot welding for achieving high quality are welding current, welding force and welding time. Generally at the manufacturing scene, welding current Vs welding time lobe diagram is used to estimate weldability because controlling welding force is not practical due to economical reasons. However new automotive steel plates have been developed to make lightweight automobiles and to improve resistance against rusting. Also the weldability of these steel plates are worst than the existing steel plates because of changing bare metal and surface plating effect. In consequence of above mentioned reasons, it is necessary to use welding force to present the lobe diagram. In this study, we obtained the welding force Vs welding current lobe diagram for commonly used GA steel plate and found that the second order repression model of tensile shear strength was useful in reducing the number of experiments, and the indentation, and thickness change during welding were used as a response to estimate quantitatively expulsion.