Design of intelligent CNC system using IEC61499 function block

Abstract

CNC machine tool is the end mechanism in the process of converting input materials into desired outputs shape reflecting the customer specifications and requirements. All executions and operation processes are fully organized and control by the CNC controller unit. As the brain for the whole system, the architecture and internal structure of the controller plays an important role in realizing intelligent functions of the CNC machine tool systems. Unfortunately, the methodology for CNC machines programming remains relatively unchanged over these years. Traditionally, CNC machine tools have rigid programming structure. Most of the CNC programs are restricted to any modification during machining operation execution. Establishing of STEP-NC as next generation data model lead to huge paradigm shift of future CNC system especially the ways of CNC being programmed. However, as a passive data model, STEP-NC does not have any intelligent functionality. Thus, to overcome these limitations, a new data processing unit for adaptive CNC controller is proposed based on IEC61499 function blocks. The main function of this unit is to establish operational decision-making function at controller level. It generates native information for a particular machine tool. Whereby, the availability of manufacturing resources and machine condition are taken into account. By establishing layered and distributed architecture, the proposed systems are expected to cover up the deficiency of current CNC controller structure. Hence, the portability, interoperability, flexibility and openness of the CNC controller structure can be further improved.