Basic Research For Machine Vision Applied In Aluminum Alloy TIG Welding

As we all known, the real working environment of welding is so hard that it is difficult to control the welding qualities in real time. For this reason, it becomes a main problem to solve in this field. Nowadays, with the development of technology, machine vision is more and more applied in welding process. It is benefit to implement intelligent operation and control in real time of welding process. Besides, aluminum alloy is one of common material, which is popularized in many fields, such as Aviation, Aerospace, Automation, Manufacture, and so on. Therefore, it is very important for theory and appliance to do some basic vision research for aluminum alloy AC welding. And it will be meaningful and helpful to handle sensing problem for welding automatic control in future.In this paper, it built high speed shooting system to capture images in welding process. When the camera frequency is as to more than 10 KHz, it acquired clear pictures of electron arc and weld pool. With the situation of 100A of AC current, it analyzed the characters of electron shape and the change of weld arc density. Especially, it discussed the weld arc and weld pool when the current is changed from EN to EP or from EP to EN. From image observation, it found the arc light is very weak; and the interference for shooting images of weld pool is less than other times. Meanwhile, according to the image processing of gray division for weld arc, it also testified that the arc light is the weakest when the current is changed.The research also showed that the light density of image will be rebound with the poppled current as current changed. According to the similar periodicity between electron number densities and the current wave form, it built the special relationship between weld image and electron number density as well, which based on the relationship between weld image and current wave form. It means there is the bridge which connects with both macro and micro.What's more, there is Linlog technology in this high speed camera. Using this image, it is helpful to get wider dynamitic range, and advances image contrast. With this technology, it acquired the clear weld pool images under big current. For collecting weld pool curve, it designed a set of algorithm especially for weld pool curve. Applied this algorithm, it got the matching curve of weld pool successfully. Compared with original image, the booboo is very small, and the quality is fantastic.