Tool Axis Vector Optimization For Five Axis Machining Of Complex Surfaces Based On Kinematic Constraints

Complex surface processing is sui Tablefor five-axis CNC machine,and the processing complexity is considerable.In actual processing,after using the CAM software to plan the path of the complex surface part,Sometimes the exported path cannot be directly applied to the actual processing of some CNC machine,The smoothness of the tool axis vector does not guarantee that the angular velocity of the rotating axis changes drastically during machining,and the tools or parts vibrate,it is not easy to guarantee the quality of the processed surface.If you blindly pursue the quality of the processed surface,the processing speed is slow,the time is long,and the cost is higher.Therefore,under the premise of ensuring the processing quality,optimizing the five-axis CNC machining tool axis vector of complex curved surfaces and improving the processing efficiency has positive and significant significance in engineering practice.This paper proposes a kinematic constraint-based tool axis vector optimization method for five-axis machining of complex curved surfaces.It can ensure that the angular acceleration of the rotation axis is constrained by the machine tool kinematics,and the movement of the rotation axis changes smoothly,the optimized cutting time is shortened,and the efficiency of machining complex surface parts is improved.The specific research content is as follows:(1)First,the background of the thesis research is introduced,and the problem of CNC machining of complex curved surfaces is explained.The thesis investigates related tool path fitting technology,tool feed speed planning technology,and tool axis vector smoothing technology.In order to realize the high-precision and high-speed machining of complex curved surfaces by CNC machine tools,relevant problems and technologies that need to be solved for five-axis CNC machining of complex curved surfaces are refined.(2)The idea of tool axis vector smoothing under the kinematic characteristics of machine is proposed.By analyzing the characteristics of complex curved surfaces,the tool path generation process for processing complex curved surfaces is given,through the kinematics and dynamics analysis of each axis of the machine tool,the maximum kinematic parameter limit and constraint conditions allowed by the machine tool are obtained.Then,this article gives the basic method and process of NC trajectory planning,including the generation of cutting contact points of the tool,the planning of the tool axis vector,the determination of the tool cutting location point,and the determination of the tool path feed speed.The specific problems and indicators of path planning for five-axis CNC machining of complex curved surfaces are given in detail.(3)In order to realize the tool path fitting of complex curved surfaces,a complex space spiral tool path fitting method with a small amount of calculation is proposed.This method expresses the tool path through NURBS curve,and use interpolation approximation method to fit the curve,realize the accurate mathematical expression of the space spiral tool path using low-order formulas,and analyzed the influence of the method in this paper on the planning of tool feed speed.This article calculates and compares with examples,it proves that the fitting method proposed in this paper has high fitting accuracy when compared with the global interpolation method and the least square method with a small amount of calculation.(4)A kinematics constraint based tool axis vector optimization method for five-axis machining of complex curved surfaces is proposed.Based on kinematic constraints,establish a multi-objective optimization model for the tool axis vector under reasonable acceleration and deceleration planning,and verify the results of the tool axis vector optimization.Establish a multi-objective optimization model of the cutting time to prevent the tool axis vector from being restricted by the optimization space range,resulting in the optimized results failing to meet expectations.This paper analyzes and compares the effects of different optimization models through calculation examples,it is proved that the optimization model proposed in this paper optimizes the tool axis vector and cutting time,it can improve processing efficiency while smoothing the tool axis vector.(5)Finally,the tool path of some model impeller blade is optimized and simulated,observing the tool interference and processing efficiency and compare and analyze with the path processing results before optimization,demonstrating the effectiveness of this method.