Research On The Tool System Control For Blisk Grinding And Polishing

The blisk is an important high precision component, which has been widely used in the aircraft engine. When compares to the traditional blade, the advantages it shows are very outstanding. The tenon and locking device of the blisk has been dislodged, which can lower the airflow loss between the tenon root and mortise. The weight of the engine has been reduced, the structure of the engine has been simplified, and also the engine trust-weight ratio has been greatly improved. Despite these advantages, there also exists some problem. To achieve the excellent performance, the blisk usually use the advanced composite materials(titanium alloy and nickel base alloy), which is hard to be manufactured and also with the high temperature resistant. Due to its complex structure, the manual polishing is still the major method to process the blisk in our country at present, which results in the low efficiency and precision. However, there are some research institutions have begun to explore the processing method of the blisk, which has made some progress. On the contrary, in some foreign country, the blisk processing has basically formed the fully digital manufacturing unit, it includes rough machining, finish machining, automation polishing and detection, and also the automatic feeding. Therefore, some research about the problems listed above is meaningfully to be made. In this paper, based on the self-developed double column seven axis five linkage machine tool, the control program for the blisk abrasive belt grinding tools system has been designed and also the integration of the polishing measurement for the blisk has been achieved.Based on the structural characteristics of the blisk, the structure of the double column seven axis five linkage machine tool and the abrasive belt grinding characteristics, the control mode of the tool system has been identified. Among them, the concave and convex surface use the abrasive belt constant pressure grinding method, which belongs to the typical valve control cylinder model. The blade inlet and exhaust edge use the tension the rodless cylinder given to the abrasive belt to polishing. The blade root use the flexible grinding head with the characteristics of the small size and the flexibility to polish. The profile measuring tool system adopts the PLC switch control. Using the probe to finish the measurement in situ of the blade, which greatly reduced the clamping error and improved the measurement accuracy.As the main surface, the concave and convex surface adopts the constant pressure control. Through the analysis about the characteristics of the proportional valve and low friction cylinder, the nonlinear mathematical model of the pneumatic servo pressure control system has been established by using the mechanism modeling method. Also, through the off-line parameter identification in MATLAB, the mathematical model of the pneumatic servo system has been achieved and the system closed loop stability is analyzed.Based on the nonlinear and time-varying characteristics of the pneumatic system, the models of PID control and the Fuzzy PID control are designed. Through the simulation and experiment, the parameters of the PID are set to make them achieve the ideal range. At the same time, the system of constant pressure polishing background control program is established by using the MATLAB/Simulink. By comparing the experiment results, some conclusions can be achieved. For the controlled object with the accurate mathematical model, the control effect is essentially the same either in PID control or in Fuzzy PID control. But for the pneumatic servo system with the uncertain mathematical model, the Fuzzy PID is more useful. It has more ideal response time, overshoot and steady state.By using the MATLAB/GUIDE Tools, the software of the constant pressure grinding control is developed, which realizes the quick change and transfer for the parameters, greatly reduces the time of changing the parameter and also improves the polishing efficiency of the blisk. Finally using the Kistler dynamometer to respectively test the different grinding force and gauging the surface roughness, verify the effectiveness of the Fuzzy PID control algorithm.