Dynamic behavior of the weld pool in stationary GMAW

Abstract

Abstract. Because hump formation limits welding productivity, better understanding of the humping phenomena during the welding process is needed to access to process modifications that decrease the tendency for hump formation and then allow higher productivity welding. From a physical point of view, the mechanism identified is the Rayleigh instability initiated by strong surface tension gradient which induces a variation of kinetic flow. But the causes of the appearance of this instability are not yet well explained. Because of the phenomena complex and multi-physics, we chose in first step to conduct an analysis of the characteristic times involved in weld pool in pulsed stationary GMAW. The goal is to study the dynamic behavior of the weld pool, using our experimental multiphysics approach. The experimental tool and methodology developed to understand these fast phenomena are presented first: frames acquisition with high speed digital camera and specific optical devices, numerical library. The analysis of geometric parameters of the weld pool during welding operation are presented in the last part: we observe the variations of wetting angles (or contact lines angles), the base and the height of the weld pool (macro-drop) versus weld time.

Image processing and geometrical analysis for profile detection during pulsed gas metal arc welding

“…9 The experimental setup is composed of a welding generator, a data acquisition system and a high-speed camera. In this article, only details on image acquisition setup and treatment will be given.…”

“…Same procedure is used to estimate the macro drop radius and volume. 9 Droplets. The metal transfer droplet is approximate and closed with a combination of alpha-shape and graph algorithm as outlined in the previous section.…”

“…A specific setup for data acquisition has been established in the laboratory to synchronize all kinds of signals and images in position and in time. 9 The experimental setup is composed of a welding generator, a data acquisition system and a high-speed camera. In this article, only details on image acquisition setup and treatment will be given.…”