Restoration And Enhancement Of X-ray Images During Laser Welding Real-time Monitoring

With the rapidly development of Laser welding technology, laser power changed from small to large, quality and stability of laser beam improved, laser welding technology has been widely used in various industry fields. As a special welding process, the main advantage of the advanced laser welding is its large weld energy density in per unit length, high welding speed, small weld heat affected zone, small deformation, high mechanical properties of joints and weld profile dimensions do not subject to restrictions. We could get a large penetration depth used high power laser welding.Due to the opaqueness of welding metal material, it’s hard to research the welding process of metal. How to observe and analyse the internal dynamic of molten metal is the key point of research. For realize real-time monitoring of laser welding process, author utilized the strong penetrability of X-ray to observe and analyse the morphology of a molten pool and the thermal transmit of a keyhole. During laser deep penetration welding of Type304stainless steel, the X-ray images of molten pool were degraded by the disturbance and noise from the welding process and radiography devices, and were not clear enough to be recognized. This dissertation proposed several arithmetics to enhance and restore the X-ray images, such as wiener filtering, blind deconvolution, gray stretching, contrast stretching, and so on. Then the author analysed the dynamic of molten pool. Experimental result showed that the proposed arithmetics could improve the quality of X-ray images efficiently, and the contour feature of a molten pool was protruded. The distribution of molten metal had certain regularity. For realization of real-time monitoring of laser welding, this dissertation has certain meaning on theory and practice.