In this paper an automatic visual method of seam recognizing and seam tracking based on textural feature matching was proposed, in order to recognize the weld of multi-layer or multi-pass welding in which the weld is ...In this paper an automatic visual method of seam recognizing and seam tracking based on textural feature matching was proposed, in order to recognize the weld of multi-layer or multi-pass welding in which the weld is difficult to be recognized by conventional visual methods. This method focuses on the obvious difference of image textural feature between the weld region and the base metal region, as well as the similarity of the textural features along the welding direction. The method consists of the following steps ： setting image template and choosing the edge region as ROI （ region of interest ）, extracting the image textural feature of the template and the edge region, feature matching, and recognition of weld region. Experiment showed that the method proposed was effective for weld seam recognition in multi-layer welding.展开更多
The rules such as process parameters affecting joint properties and theevolution principle of weld's microstructure have been researched by adopting diffusion weldingprocess to connect SiC_w/6061Al composite. Expe...The rules such as process parameters affecting joint properties and theevolution principle of weld's microstructure have been researched by adopting diffusion weldingprocess to connect SiC_w/6061Al composite. Experimental results show that there exists a criticaltemperature region between solid and liquid phase line of SiC_w/6061Al composite, and the regionwill shrink with the increasing of welding pressure. When diffusion welding occurred under thecritical temperature region, welding joint exhibits bad property of bonding, and the matrix and thereinforcement can't bond effectively. When diffusion welding occurred in the critical temperatureregion, the strength of welding joint changes widely with the variation of welding temperature. Whenwelding temperature varies in 10 deg C, the strength of welding joint will change obviously. Onlywhen welding temperature is higher than the critical temperature region, stable joint properties canbe obtained. Simultaneously the matrix and the reinforcement has better interfacial bonded indiffusion welding interface, and no obvious interface reaction occurred, and thus diffusion weldingof SiC_w/6061 Al composite can be successfully realized.展开更多
A series of laser-TIG double-side welding experiments for aluminum alloys were carried out to investigate the heat efficiency of the process. The melting efficiency was introduced to evaluate quantitatively the degree...A series of laser-TIG double-side welding experiments for aluminum alloys were carried out to investigate the heat efficiency of the process. The melting efficiency was introduced to evaluate quantitatively the degree of the mutual effect of the laser and the arc. The results showed that the melting efficiency of laser-TIG double-side welding exceeded the sum of the laser and the arc taken separately. With the increase of heat input, the weld depth and melting efficiency of the laser and the arc were increased signifwantly. This, in fact, implies the strong mutual effect of the laser and the arc as heat sources joined simultaneously in the process. Comparatively, the higher efficiency of the laser constituent of heat sources plays the main role in the increase of the process efficiency. The phenomena of arc column convergence, increased laser absorptivity and the formation of heat accumulation region are the causes of the improvement of heat efficiency.展开更多
薄板自动化焊时产生的光反射、飞溅、粉尘等噪声使焊缝位置信息被遮挡,从而影响特征点的识别与提取。因此,提出了用连通区域的算法对焊缝的特征进行标记,并改进了连通区域算法用于提取焊缝特征点和获取其位置信息。在图像预处理之前,用...薄板自动化焊时产生的光反射、飞溅、粉尘等噪声使焊缝位置信息被遮挡,从而影响特征点的识别与提取。因此,提出了用连通区域的算法对焊缝的特征进行标记,并改进了连通区域算法用于提取焊缝特征点和获取其位置信息。在图像预处理之前,用感兴趣区域(Region of interest,ROI)方法对激光条纹进行图像分割,可滤除大量弧光、飞溅等噪声;在图像预处理的过程中,采用中值滤波和最大类间方差的二值化算法降低激光条纹附近的干扰噪声,将激光条纹与背景分离,使焊缝特征更清晰、明显;在图像预处理后,用连通区域的方法对激光条纹进行标记,通过改进的算法判断出连通区域的位置,从而识别焊缝特征点,获得焊缝特征点的位置信息。该算法不仅保留了焊缝激光条纹的边缘信息,还能在复杂的工作环境中完成焊缝特征的识别。通过对比薄板的实际间隙宽度和试验计算出的间隙宽度,该算法平均误差在0.067 mm以内,满足工业中的精度要求,适合激光视觉的焊缝跟踪过程。展开更多
基金This research is supported by the National Natural Science Foundation of China （No. 50875145） and the National High Technology Research and Development Program （＂863＂ Program） of China （Contract No. 2007AAO4Z258）.
文摘In this paper an automatic visual method of seam recognizing and seam tracking based on textural feature matching was proposed, in order to recognize the weld of multi-layer or multi-pass welding in which the weld is difficult to be recognized by conventional visual methods. This method focuses on the obvious difference of image textural feature between the weld region and the base metal region, as well as the similarity of the textural features along the welding direction. The method consists of the following steps ： setting image template and choosing the edge region as ROI （ region of interest ）, extracting the image textural feature of the template and the edge region, feature matching, and recognition of weld region. Experiment showed that the method proposed was effective for weld seam recognition in multi-layer welding.
文摘The rules such as process parameters affecting joint properties and theevolution principle of weld's microstructure have been researched by adopting diffusion weldingprocess to connect SiC_w/6061Al composite. Experimental results show that there exists a criticaltemperature region between solid and liquid phase line of SiC_w/6061Al composite, and the regionwill shrink with the increasing of welding pressure. When diffusion welding occurred under thecritical temperature region, welding joint exhibits bad property of bonding, and the matrix and thereinforcement can't bond effectively. When diffusion welding occurred in the critical temperatureregion, the strength of welding joint changes widely with the variation of welding temperature. Whenwelding temperature varies in 10 deg C, the strength of welding joint will change obviously. Onlywhen welding temperature is higher than the critical temperature region, stable joint properties canbe obtained. Simultaneously the matrix and the reinforcement has better interfacial bonded indiffusion welding interface, and no obvious interface reaction occurred, and thus diffusion weldingof SiC_w/6061 Al composite can be successfully realized.
文摘A series of laser-TIG double-side welding experiments for aluminum alloys were carried out to investigate the heat efficiency of the process. The melting efficiency was introduced to evaluate quantitatively the degree of the mutual effect of the laser and the arc. The results showed that the melting efficiency of laser-TIG double-side welding exceeded the sum of the laser and the arc taken separately. With the increase of heat input, the weld depth and melting efficiency of the laser and the arc were increased signifwantly. This, in fact, implies the strong mutual effect of the laser and the arc as heat sources joined simultaneously in the process. Comparatively, the higher efficiency of the laser constituent of heat sources plays the main role in the increase of the process efficiency. The phenomena of arc column convergence, increased laser absorptivity and the formation of heat accumulation region are the causes of the improvement of heat efficiency.
文摘薄板自动化焊时产生的光反射、飞溅、粉尘等噪声使焊缝位置信息被遮挡,从而影响特征点的识别与提取。因此,提出了用连通区域的算法对焊缝的特征进行标记,并改进了连通区域算法用于提取焊缝特征点和获取其位置信息。在图像预处理之前,用感兴趣区域(Region of interest,ROI)方法对激光条纹进行图像分割,可滤除大量弧光、飞溅等噪声;在图像预处理的过程中,采用中值滤波和最大类间方差的二值化算法降低激光条纹附近的干扰噪声,将激光条纹与背景分离,使焊缝特征更清晰、明显;在图像预处理后,用连通区域的方法对激光条纹进行标记,通过改进的算法判断出连通区域的位置,从而识别焊缝特征点,获得焊缝特征点的位置信息。该算法不仅保留了焊缝激光条纹的边缘信息,还能在复杂的工作环境中完成焊缝特征的识别。通过对比薄板的实际间隙宽度和试验计算出的间隙宽度,该算法平均误差在0.067 mm以内,满足工业中的精度要求,适合激光视觉的焊缝跟踪过程。
