Research On Soft-PLC Control System Of Five-axis CNC Milling Machine

With the development of numerical controltechnology,five-axis CNC milling machine has gradually replacedthree-axis CNC milling machine with higer grinding accuracy andproduction efficiency in processing large,complex curved surface parts.High performance cnc system is needed to control. At present open CNCsystem is developing towards software CNC direction. SoftPLCtechnology is used to realize the switch quantity control of numericalcontrol system can solve the problem of traditional PLC closed structureand poor compatibility, can further improve the performance andopenness of CNC system.Therefore, SoftPLC control system of five-axisCNC milling machine is studied in this paper.First, different running platforms of SoftPLC system are discussed,the control scheme based on general PC and Windows XP+RTX5.0real-time operating system are chosed as the operation platforms ofSoftPLC system. After studying the position and function of PLC controlmodule in the numerical control system software, and the architecture andwork process of traditional PLC, it designs the overall structure ofSoftPLC control system in the reference IEC6113-3software model andthe modular thought. This software structure has advantage of goodreusability, easy to maintain and can be extended.Second, the implementation of SoftPLC running system is mainlystudied because it is the main body to realize the control function. Using c++object-oriented technology to convert each composition module ofsoft PLC running system, design the open interface to realizecommunication between various modules, the task scheduling of SoftPLCrunning system is designed and implemented according to the schedulingprinciple of multi-threaded programs.Then, after analyzing the deficiency of CNC underlyingcommunication interface and introducing the related content ofSERCOS-III interface, the overall structure of the CNC system forfive-axis CNC milling machine based on the SERCOS-III interface isgiven, and the paper designs and developments SoftPLC I/O interface hardware, gives the software development processing and writes thecommunication control programs between SoftPLC system and I/O inputand output module.Finally, the text analysis the specific content which five-axis CNCmilling machine SoftPLC control system need to control. Throughimplementation the spindle rotation control programs, the validity ofSoftPLC control system is verified.