Research On The Key Technology Of Robotic Abrasive Belt Grinding Of Compressor Blade

The blade,as the key components involved in energy conversion in aero-engine,gas turbine and steam turbine,plays a decisive role in the overall performance,efficiency and life,its geometrical accuracy and surface quality directly affect the efficiency of energy and power equipment.Generally,the blades need to experience complicated machining processes after casting or forging,and the final finishing operation almost relies on the abrasive belt grinding to ensure the contour accuracy and surface smoothness.Manual belt grinding and multi-axis NC belt grinding are deemed to be the dominated finishing modes,however they are under the situation of the serious finishing environment,poor surface consistency,low machining efficiency and high price,of abrasive belt grinder,bad universality.As a new type of finishing mode,robotic abrasive belt grinding receives wide concerns and has been widely developed in modern manufacturing industry owing to its advantages of high efficiency,excellent flexibility,large operating space and low cost.Therefore,this paper focuses on the key and system technologies of robotic belt grinding and processing of compressor blade.The specific work includes:1)According to the robotic belt grinding current situation of compressor blade,the robotic finishing and measurement platform is built to conduct the research.The hardware system includes: machining system,calibration system,measurement system and force control system,while the software system includes: robotic motion control,off-line planning,force control,measurement and integration control.2)Each coordinate frame of finishing hardware equipments are defined in the robotic belt grinding system.Compared with the traditional calibration methods of tool and workpiece coordinate frame,a new sphere-to-sphere calibration method is proposed to accurately locate the position and attitude of each device in the robot machining space.Then a new TCP-based calibration algorithm is proposed to accurately obtain the spatial position and attitude relationship between robot and scanner by the optimization of traditional hand-eye calibration algorithm,finally the clamping error of workpiece can be eliminated to improve the machining accuracy.3)In the robotic belt grinding process,a hybrid force/positon control algorithm combined with PI/PD is proposed in the paper based on the six-dimensional transducer which is installed on the robotic end-effector.While a PID force control algorithm is adopted in the paper based on the one-dimensional transducer of the grinding machine.Then the active and passive force control algorithm is combined to optimize the robot finishing process by using the Kalman filter information fusion technology.The constant force control strategy is employed to the robotic abrasive belt grinding of blade which can ensure the stability of robot grinding process and improve the surface consistency.4)The orthogonal experimental test is conducted to analyze the key controllable factors which affects the robotic belt grinding quality.Then the grinding force and specific grinding energy model is built in the robotic abrasive belt grinding process from the aspects of microscopic level,and the material removal rate model is also established in the paper according to the cut-in and cut-off phenomenon in the actual machining process.Finally,the robotic abrasive belt grinding mechanisms are explored to eliminate the cut-in and cut-off phenomenon,ensure the machining contour accuracy and improve the energy utilization rate and machining quality.5)The different robotic machining styles and control technologies,global variable pressure and local constant pressure,are adopted to the robotic grinding of compressor blade which is divided into convex and concave surface,leading and trailing egde,blade root and turning angle R.Then the robotic integrity machining of compressor blade is achieved to be applied in the enterprise with the above key robotic grinding technology.The above research makes up for the shortcomings of traditional manual grinding and CNC abrasive belt grinding machine,then the automatic grinding of complex blades are realized to improve the consistency and coverage rate of the machined surface.Therefore,it could be applied to the mass production of blade enterprises.