| Complex curved surface components mainly including turbine blade,aero-engine blade,propeller and so on are generally manufactured by grinding and polishing which are widely used as the final process method.In the early 90 s,the grinding precision of similar components surface completely depended on how proficient the workers are in manufacturing,which to some extent resulted in many problems of how to effectively control components surface quality.With the rapid development of chinese S&T and economy,manual work was gradually replaced by CNC machining,the manufacturing precision and efficiency of complex curved surface components was improved a lot.However,because of the existence of some shortages of high-end CNC abrasive belt grinding machine,such as huge investment for the first time,huge scale,low flexibility and so on,therefore high-end CNC abrasive belt grinding machine can't be adapted in Single-Piece and Small-Batch production.To solve this problem,this paper has taken marine whole propeller as the research object,utilizing the robot equipped with light-weight grinding tools to realize polishing and grinding experiment for the propeller surface.The robot can solve the problems that CNC abrasive belt grinding machine has left,so robots machining complex curved surface components will become a new trend in the future.This paper is conducted around the main problems of complex curved surface manufacturing,and these problems are as follows: the processing route of robot,the selection of light-weight grinding tool,the kinematics method of robot,the method of machining process parameters optimization of robot,the off-line processing programming of robot and so on.The research results can provide crucial guidance on robot manufacturing complex curved surface components in the future.The main innovation points and research work of this paper are listed below:1.Based on the characteristics of workpiece's contour shape,this paper has accordingly established a robotic grinding system.Furthermore,This paper has determined the robot model and its end grinding tools and realized the corresponding feasibility analysis.In order to verify the correction of the robotic joint action in the process of operation,this paper has established the corresponding 3D geometric model based on the real size of robot and workpiece on the platform of UG8.0 and completed the analysis of simulation motion.2.The paper has created a robotic processing line which applies to the characteristics of propeller's surface.The traditional tool path planning methods,such as equivalent parameter method,equidistant offset method,equivalent residual height method,projective method and so on,couldn't cope with the problems that exist in some areas including the fillet of blade's root,the overlapping areas of adjacent blades and so on.For this problem,this paper has proposed a improved method to plan process line,which can repeat reverse remodeling for propeller surface and project the processing line that is isometric partitioned to the prototype surface.Then based on the results of the previous step,the contact points in the robotic processing can be extracted by isometric separating the processing line.3.This paper has analyzed the robotic grinding system with method of Descartes space coordinate transformation,and it has got the ideal position in the process of the robot operation and utilized the double vector control technology(Normal Vector and Tangential Vector on the contact points of surface)to control the posture of grinding tool.Considering the formula of bandwidth optimized by many factors such as the width of contact wheel,elastic modulus,thickness of abrasive belt and so on,the efficiency of robot grinding is consequently improved a lot.4.With the algorithm of robotic joint movement,this paper has developed the special software of robotic off-line processing program based on the open software platform of Open CASCADE(OCC),the average time to generate single program is 2-3S.Therefore this paper has solved the problem of inputting program with hands from the fundamental perspective.It can verify the correctness and rationality of processing program by generating the robotic off-line processing procedures and simulating machining in VERICUT at the same time.Besides for the phenomenon of collision and interference in the process of simulate machining,the tangential vector of contact points are adjusted dynamically,which eventually widens the areas of robot working to some extent.5.This paper has analyzed the process parameters which is very sensitive to the quality of workpiece surface in the process of robotic operation.Considering real process parameters,it has realized the reasonable combination of the process parameters by using the method of orthogonal experiment.The final results of grinding has proved the feasibility and reliability of processing a whole propeller by a robot. |
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