Towards robotic steel construction through adaptive incremental point welding

Abstract

AbstractAdditive manufacturing enables industries with a new production typology. For the metal manufacturing industry, this new means of production extends the spectrum of achievable building parts that can be fabricated and integrated into architectural designs. Consequently, this process is becoming increasingly relevant for construction industries. The application of additive manufacturing in metal fabrication industries requires high performance technology and extensive knowledge of material and process. Within this paper, we focus on the implementation of incremental point welding as a metal additive arc welding strategy. The goal is the realization and optimization of a manufacturing method which implements adaptive strategies in the control of this production process. In this research, incremental point welding is used for the production of branching structures. Incremental point welding is a type of metal arc additive manufacturing which deposits material by adding individual welding points rather than layering welding seams. This process is interesting for a number of reasons. The incremental application of individual metal drops simplifies the analysis and forecast of residual stress and temperature developments. Consistent arc initialization within point welding is hard to control and, therefore, requires further exploration. This led to the following research in developing an adaptive process. Furthermore, the potential of the process is increased by the possibility of tool-path adaptivity for a robotic system enabling the robot to produce welds at complex approach angles. This research developed a novel approach, able to manufacture complex branching structures while compensating for inaccuracies caused by the welding process using image processing and an adaptive strategy. First experiments showed the possibility to work at a range of overhang angle in addition to multiple approach angles up to 50°. This adaptive process increases the potential application of this technology for the extensions of existing structures as well as repair of metal structures through incremental point welding.