Date: 18 Jul 2013

Digital Woodworking

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Abstract

This chapter considers the evolution of the wood construction industry through methods of integrated automated fabrication, thereby achieving higher environmental sustainability, in particular in building systems which have been able to transform local materials into components with high technical performance. Five key unit manufacturing processes are identified and examined: (1) and (2) mass-change with and without the removal of wood shavings respectively, (3) machining centres, (4) deformations, (5) joining and consolidation. Two projects are thoroughly examined. The Jürgen Mayer H. firm designed the winning project, the Metropol Parasol, for the International Competition on the re-design of the Plaza de la Encarnación in Seville. The project developed around interrelated layers of public spaces. The idea of the design is to create a huge sunshade—literally a parasol, hence the name—, a forest moulded in an organic shape, which should create in a natural way an urban micro-climate favourable to the activities taking place in its shade. The parasol is cut from composite timber panels with layers of veneer placed lengthwise and crosswise to the length of the panel. A three-dimensional digital model of the entire structure of the parasol integrates all the panel widths and the dimensions of the metal connectors. This model was imported from Finnforest Merk, the timber contractor, into the CAD/CAM software system bocad-3D. From the 3D model of the structure, the system automatically worked out the NC program for controlling the Kuka robot with seven axes. For the work of each panel, the anthropomorphic robot carried out the unified manufacturing processes: cutting, milling and drilling. Reconstruction of Bari’s Teatro Petruzzelli took place in 2008 after its destruction due to an arson attack. The external dome and the roof were rebuilt as they were before the fire, preserving unaltered the original geometry and structural plan. A description is given of the rebuilding in glulam of the inner dome, which was originally built in timber and wattle-and-daub. Turning to a glue laminated timber system allowed the designers to use thinner widths, which are more efficient from the point of view of stability and consequently help increase the load bearing capacity for the equivalent span. The inner dome was pre-fabricated by making technological units and elements in the factory and later assembling them in a highly organised building site. One specific constraint and challenge for the management of the construction process was handling the parts to and into the building site. The timber contractor, Stratex, used a proprietary CAD/CAM system, developed in CadWorks, to automate the generation of pieces of the structure. The system generated the numerical control for the various unit processes of the production that were necessary to produce the finished pieces in a condition ready for assembly. Each piece of the structure, after the lamination processes of the beams or timber elements, proceeded automatically through the various processes of moulding, rubbing down, pre-drilling, matching and finishing.