Tool-Path Planning With Dynamical Constraints For Impeller NC Machining

The integral impeller as one of the most typical examples in complex surface parts is widely used in aerospace, aviation, electric power, energy resource and other many industries. However, because of the complex structure and special use, the integral impeller is generally machined by5-axis Numerical Control (NC) machine. In the process of5-axis machining, the feed rate, acceleration and cutting force fluctuate violently. So, the NC machining technology is the important and difficult problem in machinery manufacturing all the time. In this thesis, in order to solve the problem of move fluctuation of cutter and machine tool, a method of tool-path planning with dynamical constraints is presented. Taking semishrouded integral impeller for example, tool-path is planned with dynamical constraints to generate the cutter location data and NC programs that move continuously and improve the machining quality and efficient.Firstly, movement characteristics of the tool and machine-tool in5-axis machining are deeply studied and two constraint conditions for tool-path planning of integral impeller are presented:①Feed rates and accelerations of the cutter and moving axes of the machine tool are continuous.②Moving peak values of any axes of the machine tool must be no more than the allowable maximum values of the machine tool. Meanwhile, the allowable feed rate and acceleration maximum values of the given machine-tool are worked out.Secondly, the method of integral impeller geometric modeling based on non-uniform B-spline is researched, and programs are written in Matlab to display the3-D model of integral impeller.Thirdly, structure feature of the semishrouded integral impeller is researched and its general machining process is given. Then, the tool-path planning of the integral impeller is finished including finishing and roughing. In this process, the dynamical constraint conditions are particularly considered and make the step length continuous and tool orientation smooth.Finally, the post-process program for the special machine tool and NC system is written to generate NC machining programs. Vericut is used to simulate these NC programs, and an actual machining experiment is taken to prove the methods and theories right in the thesis.