Trajectory Planning Strategy for Multidirectional Wire-Arc Additive Manufacturing

Abstract

Robotic systems in additive manufacturing (AM) processes offer new possibilities to meet constantly growing requirements for product individualization and small batch sizes. Solids are produced by the layered addition of material, which represents a benefit compared to conventional processes, especially in the production of complex geometries with cavities and undercuts. Recently, research into the entire process of AM from CAD models to the execution of an optimized trajectory has moved into focus. This is motivated by the use of Multidirectional Additive Manufacturing (MDAM) for Wire Arc Additive Manufacturing (WAAM). Since the material is fed eccentrically, the freedom of movement of the welding torch is strongly restricted. The novel procedure of pure manipulation of the component (with six degrees of freedom) can therefore avoid this problem and obtains optimization potentials. This paper gives an overview of the characteristics of MDAM for WAAM processes. Besides an introduction to the extended MDAM process chain, a method for optimizing trajectories is presented and analyzed. To improve the welding result, orientation tolerances are applied to the unique path supporting poses along the welding path. Additionally, implementing a custom cost function for the trajectory optimization has a positive impact on the acceleration and jerk levels. The generated trajectories thus follow the specified welding path with reduced acceleration and jerk.