The Research And Realization Of Hybrid Polishing Machine Tool Contorl System For Vane

The vane is the core components of steam turbine, turbine,aircraft engines. Inorder to improve the efficiency of grinding and polishing processing, reduce themanufacturing cost of the blade precision manufacturing. Intelligence and precisionmanufacturing researching team of Jilin University developed the hybrid polishingand grinding machine tool for vane.It’s capable of posture adjustment according to thechange of vane surface shape with5degree of freedom. In order to ensure machiningquality. This paper focus on the research of buildding the hardware structure of thecontrol system,and research on the strategy of machining motion control, as well asresearch on the implementation of software and GUI development.The control system of machine tool is constructed with PC as the maincomponents with the multi axis motion controller Turbo PMAC2which have8motorcontrol channel to meet the requirements of multi axis linkage. Through the ACC-8sinterface board, the PMAC is capable of sending the PLUS and DIR signal to themotor drivers to control the motor movement. the ACC-8s also can and receive thefeedback signal.The LF-185Heidenhain gratings on X,Y aixs send the sinusoidalsignal of1Vpp amplitude to the ISC11-4SCR signal converter to subdivision and turninto the signal that is able to input to the ACC-8s,in order to realize the closedloop.Then the three electric cylinders of the parallel mechanism use the lineardisplacement sensor as a position detection device due to its structure,the signal is gathered by the7660B Data acquisition card to real-time monitoring the pose ofparallel mechanism.The software and GUI design for control system of machine tool based on theVC++platform, applicate its MFC framework for the development of softwareinterface. It’s capable to implement the motor control in PC terminal by the functioncall made through dynamic link library of PMAC with VC platform. With this moreintuitive and simple control button to simplify the complex operation of PMAC,theoperator can reduce the misoperation. The control system software includes datadisplay, machine manual control, the axis position monitoring and automaticprocessing module etc. The calculation of kinematics, trajectory data reading andprocessing are also integrated in the software.When the machine grinding the vane,it required the posture adjustmentaccording to the actual morphology of vane surface, the adjustment angle base on thenormal vector of the trajectory point. The normal vector can not be directly,so inthis paper proposed a method to calculate the normal vector by using curve fitting andpartial derivative base on the three coordinate measuring points data of vane surface.This method fitting two high-order curve respectively along X and Y direction on thesolving point. Then partial derivative the two curves at the solving point.the normalvector can be solved by this two partial derivative vector. The effectiveness of thismethod is verified by using the ellipsoid discrete point data with arc fitting, themaximum error of the calculation is0.008radian.The hybrid polishing using PVT interpolation model combined with theempirical formula of grinding force for motion control. In order to ensure theeffective removal and the stable of the machine tool. With the PVT interpolationmodel, it need to determine the three parameters of P, V, T to achieve to determinethe three parameters machine tool axis motion control to realize the accurate motioncontrol of the motors.The polishing trajectory determines its parameters P. Then byusing the empirical formula of constant grinding to get the function of dwell time withthe process parameters in each points. And by fitting the curve of the grinding path to get the integral curve of dwell time. Through the above two steps, it’s able to obtainthe time parameter T. After that constructed the equations with P and T in each point,can get the three diagonal linear equations for sloving the instantaneous accelerationof each point. Slove this equations with thomas method and integrate with the solutionof the acceleration can obtain speed parameter V of each point.With the threeparameters of each path point associated with each other it’s able to control themotion more reasonable.