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Shape-driven control of layer height in robotic wire and arc additive manufacturing

Bohao Xu (Department of Mechanical Engineering, Dalian Jiaotong University, Dalian, China)
Xiaodong Tan (Department of Mechanical Engineering, Dalian Jiaotong University, Dalian, China)
Xizhi Gu (Department of Mechanical Engineering, Tsinghua University, Beijing, China)
Donghong Ding (School of Mechatronics Engineering, Foshan University, Foshan, China)
Yuelin Deng (School of Automation, Beijing Institute of Technology, Beijing, China)
Zhe Chen (School of Automation, Beijing University of Posts and Telecommunications, Beijing, China)
Jing Xu (Department of Mechanical Engineering, Tsinghua University, Beijing, China)

Rapid Prototyping Journal

ISSN: 1355-2546

Article publication date: 30 September 2019

Issue publication date: 7 November 2019

344

Abstract

Purpose

Once an uneven substrate is aligned, traditional control theories and methods can be used on it, so aligning is of great significance for the development of wire and arc additive manufacturing (WAAM). This paper aims to propose a shape-driven control method for aligning a substrate with slopes to expand the application of WAAM.

Design/methodology/approach

A substrate with slopes must be aligned by depositing weld beads with slopes. First, considering the large height differences of slopes, multi-layer deposition is needed, and the number of layer of weld beads must be ascertained. Second, the change in the deposition rate is controlled as a ramp function to generate weld beads with slopes. Third, the variation of the deposition rate must be fine-tuned to compensate for the deviation between the actual and theoretical layer heights at the deposition of each layer. Finally, the parameters of the ramp functions at the deposition of each layer are determined through an optimization method.

Findings

First, to model the response function of layer height to deposition rate, the experiments are conducted with the deposition rate jumping from 4 to 8 mm/s and from 8 to 4 mm/s. When the deposition rate jumps from 4 to 8 mm/s and from 8 to 4 mm/s, the difference in the height of each layer decreases as the number of layer increases. Second, the variation of the deposition rate can be fine-tuned based on the deviation between the measured and theoretical layer heights because the variation of the deposition rate is proportional to the layer height when the initial and end deposition rates are near 4 or 8 mm/s, respectively. Third, the experimental results demonstrate that the proposed method is effective for single-layer aligning and aligning a substrate with one or more slopes.

Originality/value

The proposed method can expand the application of WAAM to an uneven substrate with slopes and lays the foundation for aligning tasks focused on uneven substrates with more complex shapes.

Keywords

Acknowledgements

This work is supported by National Key R&D Program of China(2016YFE0206200); the National Natural Science Foundation of China (NSFC) (No. U1613205 and No. 51675291); State Key Laboratory of China (SKLT2018C04).

Citation

Xu, B., Tan, X., Gu, X., Ding, D., Deng, Y., Chen, Z. and Xu, J. (2019), "Shape-driven control of layer height in robotic wire and arc additive manufacturing", Rapid Prototyping Journal, Vol. 25 No. 10, pp. 1637-1646. https://doi.org/10.1108/RPJ-11-2018-0295

Publisher

:

Emerald Publishing Limited

Copyright © 2019, Emerald Publishing Limited

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