ABSTRACT Reconfigurable manufacturing systems were developed as a proposed solution to the varying market and customer requirements present in today’s global market. The systems are designed to offer adaptability in machining functions and processes. This adaptive capability requires access to a selection of tools. The development of reconfigurable manufacturing systems has mainly been focused on the machine tools themselves. Methods of supplying tools to these machines need to be researched. This paper does so, presenting a tool-changing unit that offers a solution to this need. It then discusses the enabling technologies that would allow for automatic integration and diagnostic abilities of the unit.43859
1. INTRODUCTION
Modern manufacturing demands require that producers adjust rapidly to changes in the market. These changes could be in the form of variations in production volume and/or mix.Customers are also demanding customised parts and products. This makes it necessary to have even more flexible manufacturing systems than are currently available. In response to this manufacturing climate, researchers developed the concept of ‘reconfigurable manufacturing systems’ in the mid- to late-1990s [1].
Reconfigurable manufacturing systems are designed at the outset to offer adaptability in both hardware and software. They are required to be able to respond to the varying manufacturing demands that exist in the current industrial environment. The machine tools that make up these systems must be able to deliver an array of functionality and processing
capability. A selection of tools is therefore required to perform these operations. This necessitates rapid tool-changing to promote an efficient and cost effective manufacturing process. Along with this, the reconfiguration of the manufacturing equipment gives rise to the need for an in-process calibration procedure to ensure machining accuracy and timely part production. Reconfigurable machine tools will not be able to effectively function without an adaptable tool supply system.
Reconfigurable manufacturing systems (RMS) have six core characteristics [2], [15]:modularity; integrability; customisation; convertability; scalability; and diagnosability.When designing systems within this paradigm, a conscious effort must be made to keep to these specifications.
A subset of RMS known as ‘modular reconfigurable machines’ has been researched and formulated [3]. While the other characteristics of RMS design have not been neglected, this subset emphasises modular building blocks as the foundation for varying the system’s output, functionality, and degrees of freedom. It is within this subset and framework that a
tool-changing module was developed, constructed, and tested in order to explore a solution to the problem of providing a reconfigurable manufacturing system with an automatic toolchanging capability.
Modern manufacturing equipment typically includes a tool-changing unit built into the system. In the field of modular reconfigurable machines, tool-changing units will be designed as one of the modules available to potential customers. It is therefore important that tool-changing units can be effectively integrated into the manufacturing system. Other machining modules, such as those that add an extra degree of freedom, will predominantly have hardware interfaces with the system. A tool-changing unit may not have this advantage, as it may be cumbersome and unnecessary to design a hardware interface for a module that does not specifically require rigidity constraints within the system.
This paper details the current development of a tool-changing unit, and also discusses the technologies necessary to improve its integration into the broader manufacturing system.Aspects that would allow the unit to perform a diagnostic analyis of the tools it stores is also discussed.
2. CURRENT WORK IN THE FIELD
A comprehensive state-of-the-art survey performed by Bi, Lang, Verner & Orban in 2007 [4] gives a clear breakdown of the development of reconfigurable machines, including the research emphasis up to that point. The paper categorises the work done into the areas of: