Study On The Key Technology Of 5-axis EDM CNC System Based On PMAC

Glass, ceramics, diamond and other hard or brittle materials have wide applications in many fields with their antiwear characteristic, high-temperature- resistant, and so on. However, because of their high hardness and brittleness, they can hardly be processed by ordinary methods for complex surface machining. Currently, the discharge milling and ultrasonic aid compound machining is one of the best machining way for hard or brittle material. This paper is based on a self-developed large current discharge milling machine, rotary ultrasonic aid grinding, ultrasonic aid EDM and conventional milling compounded machine tool to develop a digital control system for discharge machining. A multi-task, real-time open system is established based on NC embedded PC system that IPC used as a host computer and the PMAC used as the motion controller.The major works in this paper are follows.1. Used the Delta Tau Company's PMAC as motion controller and IPC as host computer, the high efficient and open CNC system is built based on NC embedded PC.2. The CNC system's hardware structure is designed with PMAC card. It consists of IPC, PMAC motion control card, servo systems, grating and other components. With the core of PMAC card, the real-time control of five-axis position and velocity is completed, and then the management of machine's switch signals and auxiliary control function of PLC program were achieved.3. With the Windows XP platform, the CNC system management software is programmed with Visual C++ 6.0. This host computer is used to implement parameter settings, program management, monitoring, etc. Lower computer is used to realize the real-time control, to drive the servo unit, and to monitor machine status, etc.4. According the characteristics of the machine and user needs,the PMAC's parameters are set, the system performance, zero drift, motor control servo loop and PID parameters are adjusted.5. The electric spark servo control algorithm is designed. The withdraw algorithm of independent control for spindle and contact-perception algorithm is designed too. The results of experiments validated the feasibility of the algorithms.