• 한국CDE학회논문집
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• 제8권3호
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• pp.189-200
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• 2003

This paper introduces the development of a three-dimensional jig design system for automotive body welding assembly. Recently, three-dimensional CAD systems have been introduced in the jig design area, because they reduce errors in design process and the design result can be used readily for virtual manufacturing simulation. However, to facilitate three-dimensional jig design, it is essential to customize three-dimensional CAD system for this specific design area. To accomplish this object, we first standardized the parts and units in a jig assembly, and then built the standard part library. We also developed the dedicated 3D design capabilities of jig units and a jig base. By using this system, design can be performed more intuitively, and verification and simulation of design results can be done more easily. The proposed system has been implemented using the UG/Open API of the Unigraphics system.

• Journal of Welding and Joining
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• 제29권4호
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• pp.61-66
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• 2011

The purpose of this study is to develop improved boom structures with reliable fatigue strength of weldment and lower production cost. For that purpose, multi-body dynamic analysis was performed to evaluate forces acting on arm & boom cylinders and joints of boom structure during operation of an excavator for three working postures, then stress analysis was made to investigate stress distribution around diaphragms at the bottom plate of boom structures which was known to be susceptible to fatigue failures of welded joints, and finally boom structures with optimum arrangement of diaphragms was proposed. This work mainly consists of the following two parts: part 1 focuses on multi-body dynamic analysis of excavators during operation and part 2 includes evaluations of fatigue strength of welded joints for modified boom structures.

• Journal of Welding and Joining
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• 제23권5호
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• pp.55-60
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• 2005

A precise bonding technique, transmission laser bonding using energy transfer, for polymer micro devices is presented. The irradiated IR laser beam passes through the transparent part and absorbed on the opaque part. The absorbed energy is converted into heat and bonding takes place. In order to optimize the bonding quality, the temperature profile on the interface must be obtained. Using optical measurements of the both plates, the absorbed energy can be calculated. At the wavelength of 1100nm $87.5\%$ of incident laser energy was used for bonding process from the calculation. A heat transfer model was applied for obtaining the transient temperature profile. It was found that with the power of 29.5 mW, the interface begins to melt and bond each other in 3 sec and it is in a good agreement with experiment results. The transmission IR laser bonding has a potential in the local precise bonding in MEMS or Lab-on-a-chip applications.

• Journal of Welding and Joining
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• 제30권1호
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• pp.78-84
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• 2012

Due to the inherent dimensional uncertainty, tolerances accumulate in the final assembly. Tolerance accumulation has serious effect on the performance of ECV assembly. This paper proposes a method of tolerance accumulation analysis using Monte Carlo simulation, which includes welding process in assemble process. This method can predict the final tolerance distributions of the completed assembly with the prescribed statistical tolerance distribution of each part to be assembled. With the inclusion of welding, another dimensional uncertainties due to partial melting is to be accounted as well. Partial melting of projection height was included in the tolerance propagation analysis. Verification of the proposed method was performed by making use of Monte Carlo simulation. Monte Carlo simulation results showed promising results in that we can predict the final tolerance distributions in advance before actual assembly process of precision machinery.

• 한국전자통신학회논문지
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• 제15권1호
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• pp.101-106
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• 2020

본 연구는 다양한 어셈블리 부품의 용접부 내부결함을 검사하기 위한 초음파 탐상 장비 개발에 관한 것이다. 본 연구에서는 초음파 탐상을 위하여 시스템의 모션제어 S/W, 초음파 송수신기 제어, 결함 판정 기준 설정 등의 계측 S/W 등이 설계되었으며, 양품과 불량품의 비교분석을 하기 위하여 용접결함 불량품 샘플워크 등도 제작되었다. 이와 같은 구성으로 이루어진 시스템을 통하여 어셈블리 부품 용접부의 결함 위치 및 깊이에 대한 자동검사 기능을 수행할 수 있었으며, 종전에 전문가에 의해 이루어졌던 용접부의 내부결함에 대한 판단을 시스템이 수행하도록 하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1376-1380
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• 2005

In recent automotive industry, vehicle weight can be reduced by one-step forming of tailored blanks welded with two or more sheets of metal blanks. Tailored blank(TB) welding is a production method for blanks involving welding together materials of different quality, thickness, and coating, and has proved popular in fabrication automotive parts. This paper deals with the forming characteristics of mash seam welded tailored blanks. Using these forming characteristics, the bumper beam was developed using the mash seam welded tailored blank with the different thickness. We performed the forming simulation with respect to strain distribution on blank during the stamping of the bumper rail part. Based on these results, we made some stamping tryouts with selected types of blank designs to investigate the formability of tailored blank with different thickness. During the tryouts, we knew that it was important the BHF(Blank Holding Force). We obtained to reducing 10.5% weight and cost with adapting the bumper beam of automotive component using the tailored blank of mash seam welding.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1377-1383
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• 2005

A general and efficient methodology has been developed to analyze dimensional variations of an assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated through a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld-distortion database, and tolerance analysis using the database. To establish the database, thermo-elasto-plastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is used in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assembly's dimensional variations to the part tolerances and weld distortion are obtained, which can be help improve the dimensional quality of the assembly.

• 한국멀티미디어학회논문지
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• 제20권10호
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• pp.1662-1670
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• 2017

A-Scan NDT equipment is widely used in the industrial field because it is inexpensive and easy to carry but it is necessary to have a skilled inspection specialist who is trained to analyze the waveform of ultrasonic signal. Since the welding quality is judged subjectively by the specialist, there is a problem in the reliability of the quality. In the C-Scan NDT which overcomes the shortcomings of the A-Scan, welding part can be represented in the form of two dimensional image by combining one dimensional ultrasonic waveform so that the quality of welding can be grasped without the help of specialist. In order to develop C-Scan NDT, it is necessary to develop an array type two dimensional transducer and an algorithm to composing image by combining ultrasonic signals generated from a two dimensional transducer. In addition, the noise component must be minimized in the ultrasonic signal in order to display the quality of welding in the form of images. Therefore we propose a method to remove noise component from the ultrasonic wave and construct a two dimensional ultrasonic image.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.173-178
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• 2007

시트프레임은 탑승자와 차량을 연결되는 유일한 구조부품으로 안전성을 위해서는 용접부 품질 향상이 필수적이다. 일반적으로 시트프레임의 용접에는 로봇과 전용지그시스템이 사용되며 로봇과 지그시스템의 간섭으로 인한 용접누락부가 발생할 수 있다. 본 연구에서는 기존 업체에서 사용하고 있는 용접지그시스템의 용접누락부에 대해 분석하였고 이를 해결하기 위하여 사용된 3차원 모델링 및 설계변경에 대해 논하였다. 결론적으로 시스템의 용접생산성이 향상되었고 최적의 지그시스템 개발을 통해 수동용접지그가 불필요하게 됨을 알 수 있었다.

• 한국해양공학회지
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• 제26권1호
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• pp.64-69
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• 2012

Dissimilar friction welds were produced using 15-mm diameter solid bars of chrome molybdenum steel (KS SCM440) and carbon steel (KS SM20C) to investigate their mechanical properties. The main friction welding parameters were selected to ensure good quality welds on the basis of visual examination, tensile tests, Vickers hardness surveys of the bond area and HAZ, and macro-structure investigations. The specimens were tested as-welded and post-weld heat treated (PWHT). The tensile strength of the friction welded steel bars was increased to 100% of the SM20C base metal under the condition of a heating time of more than four seconds. Optimal welding conditions were n = 2,000 (rpm), HP = 60 (MPa), UP = 100 (MPa), HT = 5 (s),and UT = 5 (s), when the total upset length was 7.8 (mm). The hardness distribution peak of the friction welded joints could be eliminated using PWHT. The two different kinds of materials were strongly mixed to show a well-combined structure of macro-particles, with no molten material, particle growth, or defects.