Synthesis of bent sheet metal parts from design features

Abstract

We consider the problem of automatically synthesizing a 2.5 D sheet-metal part in the presence of other parts in an assembly. The part is to be fabricated by cutting or stamping a single piece of sheet metal, and then bending it along straight folds. The inputs to the problem are flat regions (design features) arranged in general 3D position. These regions represent the important interfaces to other parts or to the world. The synthesized part must be realizable from a single sheet of material by cutting and bending; it must also avoid other parts in the assembly, and incorporate the flat regions. We present a three stage algorithm that solves this synthesis problem. The first stage computes a 3D global connectivity graph that indicates which pairs of features should be connected to one another by synthesized, uniform-width spars of material. The second stage calculates a folding plan that determines how the 3D shape can be folded flat. Executing this plan transforms the 3D problem into a simpler 2D one. The final stage is the spar synthesis stage which calculates constant-width, flat spars to join each pair of features that the connectivity graph indicates should be connected. These spars have constraints on their shape that arise due to obstacles, topological consistency, fold geometry, and minimal weight. We have built a simple, 3D CAD system that allows the designer to directly manipulate the design features for a single part and create simple obstacles representing other parts that must be avoided. The system synthesizes, at interactive speeds, the outline of the 2D flattened part as well as the 3D part. CR