Research On Optimization Of Feed Speed For Five-axis NC Side Milling Machining Of Impeller

Impeller parts are very important parts in mechanical equipment industry.They are widely used in aerospace,energy and power fields.The common integral impeller blade surface is the complex surface designed by free curve surface modeling technology.Due to its complex surface and high temperature and high pressure working environment,the processing of the whole impeller becomes extremely complicated because the machining accuracy should be guaranteed and the surface quality of the parts should be guaranteed.The machining equipment of integral impeller usually adopts five-axis CNC machine tool.Due to the complexity of five-axis CNC machine tool structure,the program feed speed in the processing process cannot reflect the actual speed of the tool relative to the surface of the parts.Machining with constant feed speed will cause the actual speed of the cutting tool to jump,which will affect the stability of the machining process as well as the precision and roughness of the parts surface.In this paper,the optimization of cutter feed speed in the process of nc side milling of integral impeller is studied.The main contents of this topic are:1.For the whole impeller processed,the free-form curve and surface modeling technology was used to perform cubic b-spline interpolation for the discrete value points of hub curve and cladding curve,to solve the blade edge characteristic curve,and to establish the solid model of the whole impeller.2.Based on the theory of multi-body system,the kinematics transformation model between workpiece coordinate system and machine tool coordinate system is established.In view of the integral impeller blade side fixed program feed speed in milling process cause actual feed speed of the tool relative to the workpiece surface problem,based on the numerical control machine tool feed axis movement characteristics and deceleration control principle of CNC system,made a decision to keep knife site actual feed speed relative to the workpiece surface stability for the principle,consider the feed axis feed speed motion parameters constraints optimization method,and the double axis of rotation of the turntable structure of nc machine tool control point offset to compensate.3.Based on MATLAB GUI,a special parameter optimization software was developed to plan the machining process for the five-axis CNC machining of the overall impeller.The parameter optimization software was used to optimize the parameters of the numerical control program for the machining process of the finishing side of the blade,and the generated new numerical control program was simulated for machining.The simulation results show that the parameter optimization software can fully achieve the expected function.The comparison between the speed calculation results and the speed curve shows that the speed optimization method can keep the cutter site speed stable by controlling the feed speed of the program.The sub-speed of each feed axis meets the constraint requirements,and the optimized machining efficiency increases by 35.3%.