A Visual Sensor System Designed For Threen Dimensional Sensing Of Welding Pool Surface In GTAW

The visual shape and subsurface defect of arc welding seam and assess the situation of inner forming is reflected directly by the information of arc welding pool. Therefore, the sensor for information of welding pool is significant to the forming control for intelligentized arc welding. Welding pool is dynamic, there is strong arc, high temperature and pool surface specular reflection, pool surface topography is hard to detected.A new measurement system which based on active optical visual sensor for three-dimensional welding pool surface shape is designed. The sensing principle of this system is introduced:a bunch of fringe structure linght is projected on the pool surface by projection systerm and come into being deformed stripes, a CCD camera was used to observe the images which contain abundant information of welding pool.This system has two moveable loading arms, the various components of the projection system and shoot system were installed on them. Thus you can easily adjust the angle, distance and easily to replacement device with different methods for shooting in the experiment.Reflection characteristics of the laser and arc on the weld pool surface and spatial filtering system function wre analyzed, a mathematical model of optical imaging system was gaven. Then a discussion is given in order to guide the experiments of pool image acquisition.In this paper,304 stainless steel with the GTAW welding process,4f spatial filtering system was used to obtain laser stripe images reflection from welding pool surface. The welding current, laser power, projection angle and welding direction were changed to obtain images in different parameters. The effects of these changes have been analysised. Appropriate projection angle and system parameters are found to get better images. obtaining welding pool images by camera directly and imaging panel also have been used. The characteristics and results of different methods for image acquisition have been analysised and compared. Select 4f spatial filtering system, under such circumstances, clear weld pool surface deformed laser stripe images are captured. The weld pool surface height distribution is calculated after image processing by computer and system calibration.The three-dimensional weld pool surface shape have been recovered.