The DNC System Based On CAN Field Bus And The Development Of NC Machining Codes Transmission Software

Current status of CNC machine tools in China is that the high-grade, middle-grade andlow-grade CNC are coexisted, and A large proportion of the CNC is middle-grade andlow-grade CNC. In order to improve the level of manufacturing and the production efficiencyof enterprice, it is needed to fully utilize the existing middle-grade and low-grade CNCmachine tools as we should strive to develop and produce the high-performance NC machinetools. But there are some questions such as the storage capacity of CNC is scarce, the NCsystem is multifarious and the processing and managing of CNC is standalone in the using ofthe middle-grede and low-grade CNC. The questions will direct influence the level ofmanufacturing and the production efficiency of enterprice.The main content in this paper include the structure of DNC system based on CAN fieldbus and the transmission of long NC program which belong to complex parts and automaticgenerated by CAD/CAM. Firstly, according to the above problem, the mathematical model ofDNC system based on CAN field bus is established to avoid the communication conflictthrough some influential elements have been analysed which lead to many CNC machinetools are managed intensively by one or more DNC host, and the Web integration of all kindsof CNC machine tools is realized. Secondly, long NC program is not to be saved into theCNC machine tools’ cache once because of the limited storage capacity of CNC. So, NCprogram transmission software, which based on static network DNC system based on CANbus, has been written on the basis of scheduling algorithm of static priority combination withdynamic priority on the Visual Basic platform. While DNC host can transfer the NC programwhich every CNC machine tool needed through the reasonable communication scheduling inthe machining process, NC program can be transferred into CNC system as more than oneCNC machine tools can processing to improve CNC machine tools’ processing capacity andefficiency.The design bases on the existing CNC machine tools in the machining center of LanzhouJiaotong University: two horizontal CNC lathes (CK7520), two vertical CNC mills (XK7150)and one Siemens CNC machining center. Using the RS232C serial interface attached in theequipment as the communication port, the DNC system based on CAN bus is established forverifying the accuracy and stability of DNC system and NC Machining Codes Transmissionsoftware. According to the result of field processing, the software can transmit the NC codesinto the buffer of CNC machine tools accurately and the DNC system is stable and reliable inthe process of running. The function of NC program transmission in DNC system is realized.