Modelling, Sensing, and Control of Weld Beads in Gravity Aligned and Non-Gravity Aligned Orientations for Wire Arc Additive Manufacturing

Wire Arc Additive Manufacturing (WAAM) has recently developed into a viable manufacturing process for large, complex metal parts. The WAAM process uses a Gas Metal Arc Welding (GMAW) torch mounted to an automated motion platform to execute a predetermined path plan based on a desired CAD geometry. As the desired geometry becomes more complex, it is advantageous to utilize out-of-position welding techniques used by human welders to stabilize the weld pool during the deposition of large overhangs. To ensure part accuracy and quality, adding layers of real-time control to manage various aspects of the WAAM process is critical. First, a controller is developed to maintain the contact-to-workpiece distance in the GMAW process to control the layer height of the deposited weld bead. Next, through exploring the relationship between base plate inclination angle, welding torch orientation, and bead shape, a system is developed to monitor the profile of the deposited weld bead and calculate the shape of the current bead to compare the current shape to a desired bead shape. Finally, the effect of interpass temperature on the geometric conformity of a deposited part is explored to improve the efficiency of the WAAM process and ensure geometric conformity and process stability.