The Development On CNC System Of LSWEDM Based On PMAC

Wire Cutting Electrical Discharge Machining (WEDM) is an important technique in non-traditional machining field, which deals with complicated-surfaced parts and materials that are difficult to machine. The main technical difficulties involved in development on control system of LSWEDM are pulse power and movement control. In this thesis, the present development status of WEDM both home and aboard are summarized. Based on the demand of user, a control system in LSWEDM is developed which focuses on analysis for the methods of four-axis. The research works are mainly included in this thesis as follows.Firstly, considering the characteristic of the LSWEDM, the hardware structure based on IPC and PMAC is applied. The IPC is in charge of the non real-time motion control, and the PMAC is in charge of real-time tasks. In this thesis the control principle and peripheral interfaces of PMAC card is presented and the coordinate and servo control of PMAC is analyzed. The technologies of the interface among motion controller, servo unit and coder are studied. The control system has been developed for the LSWEDM.Secondly, in the aspect of the software design, the methods of the object oriented programming(VC++) and the modularization and used. Real-time control of the servo unit, coding interpretation, system management, the transferring of the PLC program and the collection and show of the status data are all finished.Finally, the PID control algorithm is investigated in detail. Based on the work of PID in servo control and system, the system can run safely. In addition the system dynamic ability and the stability of the close loop are also analyzed and debugged.The CNC system discussed in this thesis is a real-time and multitask controlled system. Not only the kernel controller of CNC system based on PMAC shortens the development cycle and achieving reasonable configuration in resource, but also the CNC developer and the customer can increase or decrease the function modules according to their demands, and bring their technologies, experiences and skills into the open CNC.