Control of the Arc Motion in DC Plasma Spray Torch with a Cascaded Anode
JOURNAL OF THERMAL SPRAY TECHNOLOGY
Authors: Zhukovskii, Rodion; Chazelas, Christophe; Vardelle, Armelle; Rat, Vincent
Two common concerns in DC plasma torches are stability of plasma jet and anode erosion. The challenge is how to get a stable plasma jet with minimal anode erosion. This study tackles this question by using either a swirling gas injection or an external axial magnetic field applied to the Oerlikon SinplexPro (TM) plasma torch. A 3-D, time-dependent MHD model of the plasma torch operation was used to predict the value of the external magnetic field and its effect on the heat flux to the anode and plasma jet stability. The special feature of the model is to couple the gas phase and electrodes that makes it possible to follow the anode temperature evolution. For specific operation conditions (anode of o9 mm, 500 A, Ar 60 NLPM), the model predicted that the maximal value of the azimuthal self-magnetic field inducted by the arc current was 0.055 T; it also showed that an external magnetic field of 0.05 to 0.1 T could make it possible to limit the anode erosion without noticeably disturbing the plasma jet issuing from the plasma torch. We expect this approach to help to better understand the arc behavior in commercial plasma torches and control anode erosion.
Wire and arc additive manufacturing of aluminum alloy lattice structure
JOURNAL OF MANUFACTURING PROCESSES
Authors: Li Yongjie; Yu Shengfu; Chen Ying; Yu Runzhen; Shi Yusheng
Wire and arc additive manufacturing (WAAM) has been used to manufacture ER2319 aluminum alloy lattice structure, whereas a relationship of the struts diameter of lattice structure with the size and number of droplets, struts angle with the inter-layer lift and offset of the arc torch was developed. The manufacturing strategy of lattice structure by WAAM was formulated, and the aluminum alloy lattice structure demonstration was prepared where compressive properties were measured. The results show that the size of the droplet can be controlled by adjusting the current, voltage, and period within a pulse period; and then the struts diameter can be controlled by adjusting the size and number of droplets. The struts with a diameter of no less than 2.50mm were manufactured by WAAM, and its relative error was less than 2.0%. The struts angle can be controlled by adjusting the inter-layer lift and offset of the arc torch. The angle of the strut was from 15 degrees to 90 degrees, and its relative error was below 4.0%. A 3-layer pyramid lattice structure demonstration of the aluminum alloy composed of struts with a diameter of 3 mm and an angle of 45 degrees was fabricated by WAAM. The average compressive strength of ER2319 aluminum Alloy lattice structure was 58.53 MPa.