Development of a modular reconfigurable machine for reconfigurable manufacturing systems.
The Reconfigurable Manufacturing Systems (RMSs) paradigm has been formulated to encapsulate methodologies that enable manufacturing systems to effectively cope with changes in markets and products. RMSs are systems which are envisioned to be capable of a rapid change in manufacturing layouts, process configurations, machines and control components to provide a quick response to changes in the master production schedule. This research was initiated due to the necessity for new forms of production machinery to be design for RMSs, which can aid manufacturers in the adjustment of system capacity and functionality at lower costs. This thesis presents the development of Modular Reconfigurable Machines (MRMs), as a novel machining solution within the scope of RMSs. MRMs are characterized by modular mechanical structures that enable the flexibility of the machine to be adjusted in response to changes in products. The concept of adjustable flexibility implies that the flexibility of the machines may be balanced to exactly match the requirements of the system when changes in production plans occur. Product changes are managed by a variation of machining processes and Degrees of Freedom (DOF) on a platform. The modular nature of these machines permits this to be done easily and cost effectively. MRMs therefore possess an advantage over traditional machining systems, where an adjustment of system functionality would require the procurement of new machinery. Manufacturers will also have the option to purchase machines with flexibility that may be increased as needed, instead of investing in highly flexible and expensive CNC systems, with features that are often excessive and unused. Main points of this research included the development of mechanical modules for assembly into complete machines. The number and types modules used in an assembly could be changed to provide the kinematic and process optimization of the mechanical hardware according to production requirements. In conjunction to the mechanical development, a suitable Mechatronic control system will be presented. The focus of control development was the facilitation of seamless system integration between modular mechanical hardware and the controller at both hardware and software levels. The control system is modular and distributed and characterised by a “plug-in” approach to control scalability. This is complimented by a software architecture that has been developed with a focus on hardware abstraction for the management of a reconfigurable mechanical and electronic architecture. A static and dynamic analysis of the MRM system is performed for a selected mechanical configuration. The performance of the mechanical and control system is also evaluated for static and dynamic positioning accuracy for different modes of motion control. The implications for MRMs are then analysed, which include system functionality and capacity scaling, manufacturing expansion flexibility and system life spans. The research was concluded with an analysis of the challenges and problems that must be addressed before MRMs become industrially acceptable machines.