The Research Of Open CNC System Based On GT-controller

At present, most machine tools used by manufacture enterprises in China areconventional manual and old ones whose poor machining accuracy and high failure ratecannot meet the characteristics of small lot production. The enterprises have to retrofit the oldmachine tools or buy new ones in order to survive in market competition. However, buyingnew machine tools requires huge amount of investment. So CNC retrofits of conventionalmachine tools are accepted widely in developed countries. CNC control system is mostimportant factor in machine tool retrofit, which determines the performance of CNC machinetool. The popular CNC controls made by famous manufacturers usually are expensive andcan’t be customized according to the actual situation. So the development of a CNC systemwith open architecture is essential to the machine tool retrofit, which is cheap and easy toupgrade and expand in the future. This paper developed an opening architecture CNC systembased on motion controller and PC.An industrial PC is used as the host computer to communicate with a motion controllerto achieve various control functions of the designed CNC system. The control functionsinclude three levels of management, communicate and implementation. Management levelconducts the system information monitoring, trajectory planning and motion simulation.Communication level realizes the information transmission the management level andimplementation level, such as motion command, coordination positions of axis, and I/Osignals. Implementation level is to control axis, measure the axis position and check machinesignals.This paper designed and debugged the hardware system according to the analysis of theperformance parameters of the system hardware. Both NC code and DXF file input formatsare designed using C#and SQL Server software. Programs of NC code interpreter, DXFexplainer, trajectory simulation and friendly interactive interface are developed and debugged.On the basis of analyzing B-type and C-type tool radius compensation, a new tool radiuscompensation algorithm is invented to overcome the shortcomings of both B-type and C-typecompensation. The simulation and machining experiments proved that the new type toolradius compensation is useful and can improve machining quality and efficiency at sharpcorners.