Research Of Tool Path Planning Of Robotic Grinding Technology For The Aeroengine Blisk

As the core component of aero-engines,the surface machining quality of the blisk affects its comprehensive performance directly.At present,the mainstream grinding of the blisk is manual grinding.The manual grinding method is inefficient,the surface is poor in consistency,and the machining environment is harsh,which is harmful to the health of workers.The development of industrial robots provides new ideas for the grinding of the blisk.However,the robot grinding machining technology of the blisk also has the following problems: due to the large distortion of the blisk and the flow path between the blades is deep and narrow,the tool can interfere with the blisk easily during grinding;the improper posture will cause the robot to have unreachable,singular points and collision problems because of the limited of robot structure;how to improve machining efficiency and reduce machining energy consumption is also a hot spot for the robotic grinding of blisk.For these problems,this paper has carried out the corresponding research work on the robotic grinding technology of the blisk.First,a method for interference-free tool path generation for the robotic polishing of blisk is proposed for the problem of global interference between the tool and the blisk.Then,the generated tool path is transformed into the robot machining path by the inverse solution of robot kinematics,and the collision detection algorithm is used to detect the collision of the robot.For a series of problems in the tool path planning of the robot machining process,an optimization algorithm for the blisk setup is proposed.Finally,the software integration of the aforementioned research results is carried out by using UG secondary development.The main research content and innovative results of this paper are as follows:1.Interference-free tool path generation for the robotic polishing of blisk.The initial tool path is generated by the isoparametric method and the equal chord height method.Then,the shortest distance between the discrete points on the blade surface and the axis of the tool holder is used for global interference detection,and the number of discrete points is simplified by the projection method to improve the detection efficiency.Finally,the tool is rotated with the minimum angle for collision avoidance treatment,and the over-polishing problem caused by the rotating tool is eliminated by controlling the material removal depth to ensure the quality of the blade surface at the same time.2.Collision detection of robot.The forward and inverse kinematics modeling of the Comau robot is carried out by the D-H method,and then the non-interference tool path can convert into the robot motion path.A collision detection algorithm based on OBB bounding box is proposed for the collision problem during robot movement.The detection algorithm is divided into two steps.First,the shortest distance between the main axis of the bounding boxes is used to detect the collision situation in order to eliminate the bounding boxes that have not interfere;the second step is to perform the collision between the remaining bounding boxes accurately by the separation axis theory to complete the collision detection of the robot arm and other work units.3.The blisk setup optimization based on the particle swarm optimization algorithm.For the aforementioned collision problems between the robot arm and other work units,as well as the unreachable and singularity problems caused by the structural characteristics of the robot itself,corresponding constraint functions are constructed respectively.At the same time,an objective function to reduce the machining time and energy consumption is constructed by the cumulative minimum rotation angle of the robot joint axis.The particle swarm optimization algorithm is used to optimize the blisk setup to obtain the optimal clamping pose based on the constraint function and the objective function.Simulations and experiments show that the optimized machining not only solves the series of problems in the robot machining process,but also reduces machining time by 26.1%.4.Development of the blisk grinding software based on the secondary development of UG.The integrated software of the research results of this paper is development by using the secondary development of UG.The developed software has functions such as "tool-workpiece" interference detection,non-interference tool path generation,collision detection between robot arms and worktables,optimization of the blisk setup,and robot post-processing program generation,which realize the automatic planning of the robot polishing tool path of the blisk and improves the automation degree of the robotic grinding.The rough of the blade surface is 1.406μm before grinding.After the grinding experiment,the rough of the blade surface is improve to 0.358μm.The grinding result is obvious,which verifies the practicability of the software.