Development and Modeling of a Wire Straightening Mechanism for Coaxial Wire Laser-Directed Energy Deposition

Wires with small diameters (0.1 mm to 2) often retain their initial curvature when uncoiled from a spool due to plastic deformation during the winding process. A wire straightening mechanism is required in various applications, such as wire laser-directed energy deposition (WLDED) and fabrication of micro-tools for the biomedical and semiconductor industries. In WLDED, the uncoiled wires of smaller diameters often retain residual bends and deformations, leading to feeding inconsistencies and affecting the quality of the final build. While commercial wire straighteners are effective for thicker wires, they are not adequately suited for fine wires used in WLDED. To overcome this challenge, a novel wire straightening mechanism has been developed and critically analyzed. The proposed design employs a multi-stage, three-point bending roller mechanism to efficiently straighten wires of varying diameters, materials, and initial curvatures. A mathematical model has been formulated to account for the initial curvature and material spring-back, enabling the prediction of the final wire shape in a three-roller bending process. The model predicts that the optimal curvature correction occurs at a certain roller actuation, which bends the wire at a particular curvature. The model identifies the number of bending stages required for curvature correction and the effect of the initial curvature on the bending process.