Automatic Extraction and Conversion of the Bending Line from Parametric and Discrete Data for the Free-Form Bending Process

Abstract

The free-form bending process is particularly suited for small-batch components of arbitrary three-dimensional shape. Nevertheless, the target geometry is usually input as a discrete set of bending instructions. The derivation of every bending operation from the CAD file is a complex task and can result in a cumbersome decomposition process. On the other hand, a list of sequential bending operations only contains information for each individual bent. In this contribution, an automated tool for turning parametric CAD data into bending instructions and vice versa is proposed. Regardless of the input type, the target bending line is computed as a NURBS curve, which can in turn be exported as a CAD file or bending table. The tool is validated by two case studies processing, respectively, a discrete and parametric bending line description. Finally, the outcome of the presented strategy is demonstrated by performing a surface-to-surface comparison between the target CAD component and the obtained bent part.

Appendix

Translation of Line and Arcs to NURBS

See Fig. 7.

Fig. 7

Data for representing lines and arcs as NURBS: a Line; b NURBS data; c Arc $\le 90$; d Arc $\le 90$ NURBS data; e Arc $\le 180$; f Arc $\le 180$ NURBS data; g Arc $\le 2700$; h Arc $\le 2700$ NURBS data; i Arc $\le 360$; j Arc $\le 360$ NURBS data;