Motion Trajectory Planning And Analysis Of Four-axis CNC Milling For Complex Surface

In the process of studying the complex curved surface of CNC milling parts,the geometric model creation of the surface,the planning of the tool path and the optimization of the cutting parameters are of great significance for the high quality,high efficiency and low cost processing of the surface.Based on these points,the research on tool path planning generation and analysis and cutting parameter optimization to avoid interference are carried out.The numerical control machining simulation is used to verify and design the processing visual simulation system.The specific research content can be summarized as follows:(1)Based on the principle of NURBS curve and surface,construct the surface model of the part;plan the finishing process according to the geometry and processing requirements of the surface;plan the path of the tool,establish the ellipsoid head milling model,calculate the tool point and the tool axis vectorglobal under the coordinate system which are used as a basis for the subsequent track generation.(2)It is judged whether the condition of the local millability is satisfied between the curved surface and the tool,and the tool pose detection method and correction method of collision interference are proposed.Establish the objection function of the machining line space,The feasible domain of the tool attitude is solved as a constraint condition,the tool pose that satisfies the maximum machining line spacing is calculated,and a series of tool contacts are generated based on the equal residual height method,which is converted into a tool position and then fitted into trajectories.Compare the length of the track from the section method.(3)According to the prediction model of machining time and machining cost,the mathematical model of multi-objective comprehensive optimization function is established,and the optimal combination of cutting speed and feed per tooth is obtained by genetic algorithm;the processing method based on constant feed rate is The tool path pre-processing planned in this paper is combined with the optimized cutting parameters to analyze the dynamic characteristics of the machine tool,and compared with the trajectory results generated by the equidistant section method.(4)After the obtained tool position trajectory and cutting parameters are post-processed to obtain the NC program,Vericut is used to build the machine model tree and the tool and configure the simulation environment to simulate the finishing machining of the cavity surface to verify whether the NC program is reasonable,and whether the processing quality meets the requirements.(5)Design CNC machining visualization system.This system uses Visual Studio as the development platform.It calls the OpenGL graphic interface in the VC++programming environment,and collects and transmits the machine data through the DNC communication module.The DNC module adopts two architectures including C/S and B/S.The system realizes visual simulation,tool path display and error alarm during NC machining.