Octree-based production of near net shape components

Near net shape (NNS) manufacturing refers to the production of products that require a finishing operation of some kind. NNS manufacturing is important because it enables a significant reduction in: machining work, raw material usage, production time, and energy consumption. This paper presents an integrated system for the production of near net shape components based on the Octree decomposition of 3-D models. The Octree representation is used to automatically decompose and approximate the 3-D models, and to generate the robot instructions required to create assemblies of blocks secured by adhesive. Not only is the system capable of producing shapes of variable precision and complexity (including overhanging or reentrant shapes) from a variety of materials, but it also requires no production tooling (e.g., molds, dies, jigs, or fixtures). This paper details how a number of well-known Octree algorithms for subdivision, neighbor findings, and tree traversal have been modified to support this novel application. This paper ends by reporting the construction of two mechanical components in the prototype cell, and discussing the overall feasibility of the system

Algorithms for the physical rendering and assembly of octree models

Hierarchical decomposition techniques are well established for the representation of 2D images, the calculation of distance maps, and the modelling of volume data. However, recent work has suggested that their use can be extended to the manufacture of physical objects for low cost prototyping and visualization. This paper details various decomposition and assembly planning routines created to support this process. Specifically the decomposition methods are described to generate octants appropriate for the physical assembly process. Having established methods for generating suitable octrees, three different algorithms for planning the assembly of octrees are presented. The comparative performance of these different approaches is discussed

An automated system for the assembly of octree models

This paper presents a novel approach for rapid prototyping based on the octree decomposition of 3D geometric models. The proposed method, referred as OcBlox, integrates an octree modeller, an assembly planning system, and a robotic assembly cell into an integrated system that builds approximate prototypes directly from 3D model data. Given an exact 3D model this system generates an octree decomposition of it, which approximates the shape cubic units referred as "Blox". These cuboid units are automatically assembled to obtain an approximate physical prototype. This paper details the algorithms used to generate the octree's assembly sequence and demonstrates the feasibility of the OcBlox approach by describing a single resolution example of a prototype built with this automated system. An analysis of the potential of the approach to decrease the manufacturing time of physical components is detailed. Finally, the potential of OcBlox to support complex overhanging geometry is discussed

Edge-based identification of DP-features on freeform solids

Numerous applications in mechanical CAD/CAM need robust algorithms for the identification of protrusion and depression features (DP-features) on geometric models with free-form (B-Spline) surfaces. This paper reports a partitioning algorithm that first identifies the boundary edges of DP-features and then creates a surface patch to cover the depressions or isolate the protrusions. The novelty of the method lies in the use of tangent continuity between edge segments to identify DP-feature boundaries that cross multiple faces and geometries