Details

Autor(en) / Beteiligte

• Bernauer, Christian
• Leitner, Philipp
• Zapata, Avelino
• Garkusha, Pawel
• Grabmann, Sophie
• Schmoeller, Maximilian
• Zaeh, Michael F.

Titel

Segmentation-based closed-loop layer height control for enhancing stability and dimensional accuracy in wire-based laser metal deposition

Ist Teil von

• Robotics and computer-integrated manufacturing, 2024-04, Vol.86, p.102683, Article 102683

Ort / Verlag

Elsevier Ltd

Erscheinungsjahr

2024

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• •Presentation of a novel control approach to avoid process failures due to improper layer heights in wire-based laser metal deposition.•Procedure for processing the point cloud of the individual layer height profiles for the extraction of a robust height metric and the segmentation along the deposition geometry.•Analysis of the process dynamics, which are significantly influenced by the material flow within the melt pool.•Derivation of a fully discrete closed-loop control logic with the wire feed rate as the manipulated variable.•Validation of the approach on an industry-standard robotic laser metal deposition system based on the introduction of significant process disturbances, which are effectively compensated for. Laser metal deposition (LMD) with wire is a versatile additive manufacturing process used for the production of near-net-shape metal components as well as for modification and repair applications. Major advantages of using wire as the feedstock material as opposed to powder include the elimination of hazardous metal dust in the process environment and the lower costs. However, the process is highly sensitive to disturbances and requires a significant effort for parameter tuning. Thus, in order to achieve a stable process as well as defined geometric properties over many layers, dedicated approaches for monitoring and control are essential. In particular, maintaining a constant distance between the workpiece surface and the deposition head is an important prerequisite for process stability. Therefore, in this work, a layer height control system for wire-based LMD was implemented. The objective was to ensure a constant layer height corresponding to the specified height increment even in case of disturbances. Using a laser line scanner, the height profile of the part was obtained after each deposited layer. The weld beads were then divided into small segments to obtain a fully discrete height profile, and the wire feed rate for the next layer was set by an individual controller within each segment. The implemented control system was tested for its effectiveness under different disturbances, whereby significant height differences could be fully compensated within few layers. The developed segmentation approach was found to be an effective method to ensure the dimensional accuracy of LMD components. This work thus constitutes a major contribution to the advancement of fully automated additive manufacturing of metallic components.