| The complex free-form surfaces of turbine blades are widely used in aerospace industries.The traditional manual grinding methods has been difficult to meet the needs of small batch,multi specification and high-precision flexible machining of blades.Therefore,the automatic flexible machining of complex free-form surface has been put on the development agenda.However,in the practical engineering applications,there are many areas where is folded,small gap and structure interference of the blades.Therefore,it is of great significance for the development of flexible machining technology of complex free-form surfaces to build an automatic grinding system which is suitable for complex structure surfaces.At present,robot technology has made great development.Because of low cost and high flexibility of the robot,it has become the main technology used in the flexible machining of complex surfaces and one of the future development trends.Based on this background,this paper develops a robot free-form surfaces surface grinding system,which is based on industrial robot and integrates high-speed air grinding spindle and elastic small grinding tools.The main contents are as follows:(1)A high speed and small volume air grinding spindle was designed,which was installed at the robot.The structure of the spindle,the design of the impeller and the speed control were analyzed and calculated.The finite element analysis model of the spindle was established,and the static and dynamic characteristics of the spindls,such as the rigidity,natural frequency,critical speed and harmonic response,were studied.(2)Based on the Preston equation,the tool influence function(TIF)model of elastic grinding tools in different motion state of air grinding spindle was established.Compared with the actual machining effect,the correctness of the removal function model was proved.And the better removal function can be obtained by the elastic grinding tools machining with the optimal precession angle of about 30 degrees through experiments.(3)Aiming at the soft metal material aluminum alloy and hard metal material die steel,the effects of various process parameters on the removal efficiency and surface roughness were studied.And the surface of the workpiece after grinding was observed and analyzed,which provided a theoretical basis for the subsequent robot grinding of complex shape workpieces.(4)The method of tool path generation for robot surface grinding was investigated.Firstly,the grinding tool path of turbine was generated by UG.Secondly,the tool path file was transformed into a point file suitable for the Epson robot by MATLAB.Thirdly,the robot path simulation was realized in Epson RC+controller.Finally,the grinding force monitoring system was built to effectively monitor the contact force. |
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