MATHEMATICAL MODEL OF THE THERMAL STATE OF MELTED ELECTRODE SPATTERS IN OPEN ARC WELDING

Abstract

In today's environment, companies and organizations involved in welding production face the challenge of increasing process productivity, improving product quality, developing energy-saving processes, and producing competitive products. One solution to this problem is to reduce the labor intensity of processes using established welding methods. The majority of metal structures are manufactured using semiautomatic and automatic welding, manual arc welding, and flux-cored wire welding. However, all these welding methods, despite their well-known advantages, have a significant drawback: spattering of molten electrode droplets, which increases the labor intensity of welded metal structures and degrades the product's marketability. Cleaning spatter from one linear meter of a weld made using manual arc welding accounts for 20–25% of the labor intensity of the entire process, while for automatic and semiautomatic CO2 welding, it accounts for 30–40%. The simplest way to reduce the likelihood of spatter adhesion and facilitate its removal from the surface of the weld metal is to pre-apply protective coatings. The presented mathematical model of the thermal state of electrode spatter after ejection from the arc gap during open-arc welding allows one to estimate the degree of cooling of the molten metal droplet within the ambient temperature range. The temperature field of the electrode spatter was calculated at various points: at the center of the core, on the surface of the spatter, and between them, depending on the time the droplet of molten electrode metal travels before contacting the weld surface. The results obtained using the proposed mathematical model take into account the specific surface area of the spatter, its mass, its thermophysical properties, and the distance to the affected surface.