On Monitoring and Control of Machining Processes

Abstract: The thesis presents several aspects related to the industrial and academic activities associated with monitoring and control of the machining process and machine toolsA survey of the industrial situation identified some key factors for a successful implementation of monitoring and control techniques. Applicable, relatively simple, systems for cutting-process monitoring and adaptive control are available on the commercial market today but the degree of industrial utilisation of the technique is low because the systems are experienced as hard to operate and use, and are at the same time considered unreliable. In order to promote a higher degree of industrial utilisation more work has to be devoted raising the performance of the system solutions.An Integrated Supervisory Process Control (ISPC) concept is presented as an approach dealing with multi-purpose control requirements utilising the individual advantages of several sensors and modelling techniques. The ISPC system is supposed to operate as a conceptual integration of sensors, process models and different control modules. Two prototype systems, based on five-axis machining centres, for real-time control of the machining process are outlined. Different strategies for monitoring and control are developed, implemented and experimentally tried out, and the studies conducted demonstrate results that encourage further research work devoted to verification of the proposed control concept.The results obtained in the initial experiments utilising methods for process control and monitoring, such as double exponential smoothing technique (DES), multivariate monitoring applied to signal tracking and artificial neural networks applied to cutting torque control, reveal that the different techniques have potential to improve the performance of monitoring and control tasks, thus contributing to the creation of more sophisticated and reliable solutions in the ISPC concept.