Papers by Keyword: Electric Arc Welding

Abstract: Now, one of the most pressing issues in the development of petroleum engineering is increasing the efficiency of apparatus and machines, as well as reducing material, energy and labor resources. During operation, oil-refining equipment over time destroyed by welded joints due to the impact of power and temperature loads, corrosion, and other factors. The cause of damage in welded joints of oil and gas equipment can be justified by the occurrence in them of structural heterogeneity and residual stresses during and after welding. Today manual arc welding is almost the only applicable in the repair of equipment for oil and gas processing, which require welding operations. The high temperature source of energy and the difference in deformation properties of parts are the cause of the occurrence of substantial residual stresses, which cause a change in shape, a significant decrease in strength, a decrease in the corrosion resistance of the metal, which adversely affects the durability and reliability of the structure. At present, the technology of repair with due to manual arc welding with the concomitant heating of the defective area and subsequent heat treatment is used. A complex of simultaneously proceeding processes accompanies the welding process: thermal effects on the metal in the heat-affected zone, metallurgical processes in the weld pool and crystallization of the metal in the weld pool. The repair technology presented by us, which consists in a combination of ultrasonic shock vibrations and forced cooling during the welding process, allows to improve the mechanical properties of the welded joint, as well as to refuse to carry out heating during welding and subsequent heat treatment.

Abstract: The droplet transition of electrical arc welding is a complicated process that combines heat, mass and momentum transfer. A high-speed camera system with laser in the background is established to observe the fast changing process of droplet transition. A group of high-speed camera pictures which indicate that the size and shape of droplet have strong uncertainty are taken and analyzed. The results show that the randomness of droplet size and shape are decided by its internal and external random factors, such as: the changing of the length of welding wire stretched out, the fluctuation of the feed speed of welding wire etc.

Abstract: The droplet transition of electrical arc welding is a complicated process that combines heat, mass and momentum transfer. A high-speed camera system with laser in the background is established to observe the fast changing process of molten droplet transition. A group of high-speed camera pictures which indicate the droplet gravity center is unstable in welding metal transfer process are taken and analyzed. The experimental results show that the electromagnetic force is the unstable root of the droplet gravity center.

Abstract: The main flaws of electric arc welds and factors determining the quality of the welded seams are considered in this paper. In practice, welding tools and their control systems are affected by some external factors causing deviation of the weld’s quality from the specified values. Currently used control systems of welding tools do not always satisfy the requirements for quality of welded joints. Major principles of developing the adaptive control system of the welding tool are considered here and the developed functional and block diagrams of microprocessor system are presented. General equations describing the welding process are also provided and the obtained transfer function of a closed system is described.