Modeling And Control Of Cam Grinding

Digitization, intellectualization, flexibility and high precision are gradually becoming atendency in grinding machining. In order to improve domestic theory research and enhancepractice skill in the field of NC (Numerical Control) camshaft grinding, kinematic inversionmethod is applied to deduce mathematical relations between grinding wheel and cam withdifferent followers. Then multi-axes linkage control system models between cam rotationalaxis and grinding wheel feed axis are built and simulated by Matlab. Taking SiemensSINUMERIC840D NC control system as the development platform, and utilizing OEMsoftware package, OEM software which can satisfy special processing technic of camshaftgrinder is redeveloped successfully and also verified in practical grinding test. The mainresearch contents are conducted as follows:1. Deduction of mathematical relation between cam rotational angle and grinding wheelfeed. Facing the special situation that cam profile is complex, Principle of Reversion isapplied to solve the inconvenience caused by link motion between cam and its followers.After cam profiles with different followers are designed, motion trials of grinding wheelcentral point are derived. Based upon this research, mathematical models between camrotational angle and grinding wheel feed are built, which lay solid foundation for theredevelopment of OEM software and multi-axes control system modeling.2. Development of OEM software which can satisfy special processing technology.Based on840D NC system and OEM software package provided by Siemens, utilizing theinterface superiority of VB and VC++, and integrating VB program with VC++DLL file,then adding grinding wheel feed algorithm and velocity optimization strategy, OEMsoftware is developed finally.3. Establishment of single axis (Axis C and Axis X respectively), multi-axes model andconstruction of simulation platform. Based on mechanism analysis method, transferfunctions of mechanical parts in axis C and axis X are deduced. Simultaneously, PMSM isreduced form equation as DC motor model. After NC camshaft grinder three loops (CurrentLoop-Velocity Loop-Position Loop) control system models are derived gradually frominside to outside, models based axis C and axis X are built and simulated by SIMULINKin Matlab respectively, which provides theory foundation for further research in grinding mechanism of NC camshaft grinder.4. Import of velocity optimization method and reliability verification of models beforeand after optimization. Since Matlab can only deal with discrete data, after calculatingrotational angle and lift of cam, then doing one-to-one correlation with discretized time, andimporting all the data into built models, so the simulated rotational angle and rise of cam areget. With these data, simulated cam profile track is calculated. On this basis, velocityoptimization algorithm is introduced. Then model cam profile error figure after velocityoptimization and practical cam profile error figure are listed. By comparison, the modelreliablity and the feasibility of optimization strategy are verified.To sum up, this paper conducts a series of theoretical and practical research in camprofile calculating, redevelopment of OEM software in NC camshaft grinder, three loopscontrol system modeling, Matlab simulation platform construction and models reliabilityverifying. As it should be, there are some other problems for further research, such as theapplication of complex control strategy in three loops control system, construction ofself-learning&self-maintaining by utilizing virtual grinding skill, constant velocity grindingof cam and so on.