Shoe last machining using virtual digitising

Abstract

Shoe lasts are the moulds used in the footwear industries in order to mount the shoe. Most of the machines used in the sector to make lasts are simply mechanical copiers. CAD/CAM systems have just arrived to the shoe last market but its accuracy and efficiency is not better than traditional machines, for this reason new systems have difficulty to implant. Presented in the paper there is a tool path generation algorithm that takes the advantages of traditional copier systems that do not fulfil the CNC standards. The tool path is computed from a “virtually digitised” model of the last surface. The algorithm is then analysed in terms of computing cost and accuracy and refined by applying a series of optimisations. Some computer architectures are proposed in order to reduce the computation time. The proposed algorithm has been successfully implemented in a commercial CAD/CAM system specialised in shoe last making. Finally, some illustrative examples are shown.