Research And Development Of Special-shaped Piston Turning CNC System Based On TwinCAT

As the key component of engine, piston works in the environment of high temperature and high pressure. Because of deformation, circle-shape piston will cause problems as noise and gas leakage, which would affect the performance of engine. In order to offset the deformation and build the high-rigidity oil film, the non-circular piston surface was designed. As the non-circular piston surface is a complex 3-d surface, and the requirement of machining accuracy is very high, the all digital soft-model CNC lathe is usually used.As present piston turning CNC systems exist problems as less of openness, reliability and low spindle speed, the all-software solution to piston turning CNC system based on PC. was put forward, and the system was developed in TwinCAT environment. The main research work is described as follows:(1) The characteristic and main processing methods of piston surface were introduced. Point at CNC system, the research status at home and at abroad was summarized, and the all-software solution to piston turning CNC system based on PC was put forward.(2)In order to build the data model of piston surface, the commonly used piston surfaces were analyzed in three aspects:the axial generatrix, the cross section ellipse and the change of ellipticity. The cubic spline Interpolation method was used to form the data model of piston surface, which was verified in MATLAB.(3) The processing principle of piston surface was introduced, and the control demands of piston lathe, especially the real-time ability and the PLC circle period were analyzed. The EtherCAT real-time bus and TwinCAT environment were introduced. On the basis of above work, the hardware architecture of piston turning CNC system based on TwinCAT was given, the control method of common axis and axis U were also designed.(4) The motion control program was developed in TwinCAT environment, and the HMI was developed in Visual Studio 2008 environment using C Sharp language. The communication between TwinCAT and HMI was built using ADS.(5) The experiment platform was established using Beckhoff products. The common motion control functions were verified while experiment, and the high-frequency responding function of axis U was verified while simulation.