Detection of Weld Pool Width during Strong Arc Disturbance Environment

Abstract

Detecting the weld pool width is prerequisite to control the welding quality. However, in an arc welding process, it is difficult to obtain a clear image of weld pool due to strong arc disturbance. A method is proposed to lessen the arc disturbance and obtain the width of a weld pool. A camera was used to capture the weld pool images during the arc welding process. The frequency domain filter combined with spatial processing algorithms were used to depress the noises in the pool image. During arc welding, the weld pool was in a liquid state and showed specular reflection due to the arc light effects. Because of the specular reflection, edges of the weld pool exhibited different brightness from that of the internal weld pool where a camera hangs. According to this phenomenon, it was easy to recognize the outlines of the internal and external weld pool. After the image noise of the weld pool was eliminated by an image filtering algorithm, then the line scanning on the image was carried out. It was crystal-clear that the external edge and internal edge demonstrate different grey levels. Therefore the method could be utilized to identify and extract the internal weld pool width and external weld pool width.