Year

2005

Degree Name

Doctor of Philosophy

Department

School of Electrical, Computer and Telecommunications Engineering - Faculty of Informatics

Abstract

This thesis describes research in intelligent automated drilling of carbon fibre composites. This work has been motivated by the aircraft industry where there is a significant interest in automating part of the production process to improve productivity and consistency. The requirements for automated drilling as well as problems inherent in drilling composites are addressed. Drilling Forces and moments are nvestigated and used to model the drilling process. A mathematical model is developed to represent the thrust forces and this model also accounts for aging of the tool. The quality of the holes produced was investigated and parameters such as surface finish, break outs and size of the holes were related to the drilling parameters and forces generated. A decision making algorithm has been designed to enable parameters to be varied during the drilling operation to maintain optimum conditions. This decision making algorithm takes into account inherent system limits and uses information such as age of the tool and maximum force allowed to provide the spindle speed and feed rate to be used at each stage of the drilling process. The aim of this algorithm is to choose the parameters which will minimize drilling time and tool wear while maintaining quality of the holes and respecting the initial conditions of maximum thrust force. The developed system has been mplemented and shown to successfully drill holes of acceptable quality despite inherent aging of drill bits while maximising productivity.

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