• 대한기계학회논문집
• /
• 제10권2호
• /
• pp.241-246
• /
• 1986

본 연구에서는 산업 현장에 쉽게 적용할 수 있도록 측정과 설치가 용이한 용접 모재간에 가해지는 전압(weld voltage)파형에서 용접 변수를 구하고, 실험으로 구한 용접 강도와의 상관 관계로부터, 점용접 품질 감시체제를 개발하고자 한다. 전압 파형에서 용접 변수를 구하기 위하여 추계 모델링 기법을 적용하고, 구해진 모 델로부터 분산 해석(dispersion analysis)을 통하여 용접 변수를 찾으며, 동시에 전극 변위 곡선을 실험적으로 구하여서, 분산 해석 방법의 신뢰도를 검사 하고자 한다.

• Journal of Mechanical Science and Technology
• /
• 제19권10호
• /
• pp.1856-1863
• /
• 2005

In this study, a visual sensor system for weld seam tracking the I-butt weld joints in GMA welding was constructed. The sensor system consists of a CCD camera, a diode laser with a cylindrical lens and a band-pass-filter to overcome the degrading of image due to spatters and arc light. In order to obtain the enhanced image, quantitative relationship between laser intensity and iris opening was investigated. Throughout the repeated experiments, the shutter speed was set at 1/1000 second for minimizing the effect of spatters on the image, and therefore the image without the spatter traces could be obtained. Region of interest was defined from the entire image and gray level of the searched laser stripe was compared to that of weld line. The differences between these gray levels lead to spot the position of weld joint using central difference method. The results showed that, as long as weld line is within $\pm15^{o}$ from the longitudinal straight line, the system constructed in this study could track the weld line successfully. Since the processing time is no longer than 0.05 sec, it is expected that the developed method could be adopted to high speed welding such as laser welding.

• Journal of Welding and Joining
• /
• 제16권6호
• /
• pp.68-76
• /
• 1998

A CCD camera with a laser stripe was applied to realized the automatic weld seam tracking. The 3-dimensional information obtained from the vision system made it possible to generate the weld torch path. The adaptive Hough transformation was used to extract laser stripes an to obtain specific weld points. It takes relatively long time to process image on-line control using the basic control using the basic Hough transformation, but it has a tendency of robustness over the noises such as spatter. For this reason, it was complemented with adaptive Hough transformation to have an on-line processing ability for scanning specific weld points. The dead zone, where the sensing of weld line is impossible, was eliminated by rotating the camera with its rotating axis centered at the weld torch. When weld lines were detected, the camera angle was controlled in order to get the minimum image data for sensing of weld lines. Consequently, the image processing time was reduced.

• Journal of Welding and Joining
• /
• 제15권1호
• /
• pp.81-91
• /
• 1997

In this study, a magnetic sensor to make use of eddy current was developed to detect the weld seam of butt joint in the sheet metal arc welding. This system consist of the sensor device for detecting the weld line, the servo control device for driving the weld torch movement and the control unit. A signal processing was applied to smooth the output signal of the sensor. The weld joint was determined by using a 1st order differential method. To improve tracking accuracy of the system, moving average method which has an effect of proportional and weighted integral control was applied to a series of the weld joint positions obtained above. The weld line for tracking was generated by using data regeneration algorithm. Based on these results, each servo motor was controlled by pulse generator. From experimental results, it was revealed that this system has excellent detecting ability for weld line and seam tracking ability.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집A
• /
• pp.786-791
• /
• 2000

The purpose of this study is to investigate quantitatively the effects of drawbead dimensions to the weld line movements for the deep drawing of the tailor welded blanks. Square blanks have been used and five different circular drawbeads were installed in experimental apparatus. The differences in the weld-line movements and the tendencies of the strain distributions in thickness were investigated by experimental and analytical methods. The results of the weldline movement show that the smaller the radius of drawbead installed, the larger the values of movements. Also it is shown for thickness strain in central and diagonal direction that the larger the dimension of drawbead, the larger the values of maximum thickness strain. The drawbead adds the additional restraining forces to the blank, hence the movement of weld line could be controlled by the adequate drawbead installation

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1998년도 제2회 박판성형심포지엄 논문집 박판성형기술의 현재와 미래
• /
• pp.121-130
• /
• 1998

In order to analyze the forming characteristics of laser welded tailored blanks, laser welded blanks of different thickness and strength combinations were prepared and tensile, stretching, stretch flanging and deep drawing tests were done. The tensile elongation perpendicular to the weld line, stretching and stretch flanging formability decreased with increasing the deformation restraining force (strength ${\times}$ thickness) ratio between two welded sheets. The tensile elongation along weld line reached a value above 90% of the single sheet's elongation. Stretch flanging formability was reduced to approximately 10% of the single sheet value when the deformation restraining force ratio between two welded sheets was increased to two. Weld line movement of deep drawing test specimens was also affected by the strength ratio of the combined sheets, the weld line location and forming conditions. In all forming modes of tailored blanks, excessive weld line movement resulted from strain concentrations at the weaker sheet and resulted in fracture of the weaker side.

• 한국기계가공학회지
• /
• 제17권1호
• /
• pp.95-100
• /
• 2018

This study has focused on the weld-line and birefringence reduction of a plastic optic lens using over and CAE analysis in injection compression molding. A concave lens, which has a thin thickness in the center and a large difference in thickness between the center and the periphery, often causes weld-line defects during injection molding. CAE analysis has been applied to optimize the overflow design in order to reduce the weld-line defects and the polarization defects. To reduce the weld line and birefringence defects, overflow design and application using CAE analysis show that the measured birefringence values of the specimens before the overflow application were 46.8nm and 36.9nm, and the values after the over-flow application were 13.6nm and 14.0nm. From the experimental results, it is confirmed that birefringence is greatly improved when overflow is applied.

• Nuclear Engineering and Technology
• /
• 제23권1호
• /
• pp.1-11
• /
• 1991

중수로형 핵연료봉단마개용접부의 품질검 사는 금속조직 검사에 따른 용접계면에 존재하는 불연속인 용접선(weld line) 길이가 가장 중요한 검사기준이다. 본 연구에서는 저항용접에서 가장 중요한 변수인 용접열의 변화에 따라 용접계면에서 용접선 소멸과 이 용접선이 용접부에 미치는 경향을 미세조직, 인장 및 파열시험으로 조사하였고, 또 주사전자현미경을 사용하며 파단면을 조사하였다. 용접열(main heat)의 변화에 따라 실제 용접에 사용된 전류와 업셋에 따른 시편길이 감소량은 증가하였으며 이들에 관한 상관관계식을 유도하였다. 용접열 50%근 용접된 용접부의 용접업셋 크기, 기계적 강도 및 용접선 소멸등을 고려한 결과 이것이 건전한 봉단마개 용접을 위한 임계치임을 알았다. 용접열을 50%에서 75%로 변화시킴에 따라 Zircaloy-4 용접부의 미세조직은 basketweave, Widmanstatten과 마르텐사이트로 변했고, 이는 용접시 최고도달 온도에 따라 냉각속도가 크게 변화했기 때문으로 사료된다. 인장시험에 의한 용접선 파단면에서 연성파괴의 dimple 형상은 2축응력에 의해 파열된 파단면의 dimple보다 크고 깊었음이 관찰되었다. 저항업셋용접부에서의 용접전류 증가에 따른 용접선의 소멸과정은 초기용접계면에 기공 존재, 이들의 수축과 소멸 및 초기계면 수축등 3단계로 구분할 수 있었다.

• 대한전자공학회논문지SP
• /
• 제45권5호
• /
• pp.103-110
• /
• 2008

산업용 방사선영상으로부터 신뢰할만한 용접부위를 추출하는 것은 용접부의 결함을 검출하기 이전에 수행해야할 선행과제이다. 이 논문은 강판튜브 CR영상으로부터 용접특징 부위의 검출과 추출을 시도한다. 먼저 용접부위와 비용접부위로 구분된 샘플영상 160(개)를 통계 분석하여 두 부류 사이의 차이를 식별한다. 그 후 군집화 파라미터 결정을 위한 패턴분류 작업을 실시한다. 이 파라미터들은 간격, 함수부합정도 및 연속성이다. 관측된 용접영상을 선(線)별로 처리하되 각 선데이터군(群)에 가변 이동창을 적용하여 구역을 선점한다. 각 창을 구성하는 데이터의 직접 및 비용접부위 귀속여부는 국부확률선군집화 방식을 적용하여 분류한다. 순차적 과정을 거쳐 매 단계마다의 경계치 산출에 의해 두 영역 사이의 경계선을 추적하며 그 결과 용접 특징부위를 추출한다. 그리고 CR용접영상 실험을 통해 그 효과를 입증한다.

• 한국생산제조학회지
• /
• 제9권4호
• /
• pp.48-55
• /
• 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.