The global market for polished stone materials has increased significantly over the last two decades with some of the non EU countries progressively enhancing their share of the market. Significant advances have been made in technology in this sector in terms of improved extractive and transformative machinery, increased automation and introduction of diamond tools in the earlier stages of stone extraction and sawing. However, the state of the diamond tool technology for grinding and polishing is still in its infancy and the diamond tools are finding a limited use on the machines which are designed primarily for conventional abrasives and therefore lack the necessary capability for full exploitation of the advantages offered by the use of diamond tools. Also machine operation is based on operator skill and experience rather than objective assessment of the raw materials and the required product quality. This together with the absence of adequate condition monitoring and automatic control lead into non-optimal conditions which result in excessive costs and rejects. The proposed research is directed at developing cost effective diamond tools for use with multihead stone processing machines for grinding and polishing of natural stone materials. The project also aims to determine the machine tool characteristics required for maximising the advantages offerd by diamond tools, culminating in the design of a prototype machine with appropriate dynamics incorporating the necessary systems for monitoring and control of processing parameter. To achieve optimal tool and machine perfomance in terms of cost and product quality, a precise knowledge of raw material properties related to grinding and polishing is needed to allow an objective determination of machine and tool parameters, the interaction of the materials with tools at processing conditions is necessary for optimising the processing technology, the project aims to develop a stone classification system related to ease of polishing, and investigate the effect of various processing parameters on stone quality and machine throughput in order to formulate the models necessary for process optimisation. To ensure correct machine set up and control, a Knowledge Based System incorporating the stone classification system, process model, and heuristic process knowledge will be developed which would recommend the optimum machine and tool parameters on the basis of stone properties and polish quality required.
Funding SchemeCRS - Cooperative research contracts
28880 Alcala De Henares
BS16 1QY Bristol