Design And Implementation Of NC Program Interpreter Based On Five-coordinates Parallel Machine Tool

Parallel Machine Tool (PMT) has caused a revolution in the history of designing machine tool. Because PMT's principal axis is connected with machine base in multi-poles parallel structure, the rigidity of PMT and quality of process are improved.Moreover, the high-speed process can be done easily.It conquers many shortcomings of the traditional machine tool, such as tool processing only along the fixed path, the lower degree of freedom of tool-task and so on. However, the software of PMT is quite complex. As a subtask of development of CNC system for the tri-poles five degrees of freedom PMT designed by Northeast University, NC program interpreter is studied in the paper.Firstly, the standard NC language-RS274/NGC is analyzed in the paper.According as modular idea, NC program interpreter that interprets RS274/NGC is divided into scanning module, lexical analysis module, syntax parsing module and executing module.The implementation of these modules is described in detail. NC program is converted into a series of commands that are added in the command queue in task controller.Then the task controller deals with these commands according to it's current state.Secondly, Macro-program and subprogram are interpreted in the paper based on the characteristic of advanced language.They are important supplements of NC programming. It can reduce repetitive labor of NC coder using macro-program and subprogram.Finally, the paper compares B cutter radius compensation algorithm with C cutter radius compensation algorithm.Both of them are applied widely.Because tool path is straight between two tracks in the second algorithm, the process efficiency and precision are improved, and abrasion on parts is decreased. So c cutter radius compensation algorithm is analyzed and implemented in the paper.