Feedrate Optimization And Interpolation Algorithm For Five-axis Cnc Machines

Five-axis CNC machines are found wide application in various areas of modern manufacturing industry, such as aerospace industry, national defense, mould manufacturing and so on. To satisfy the requirements of high speed and high precision in CNC machining, the researches on path generation, feedrate planning, interpolation, post procession, servo control and machine assembling are all of vital importance, among which, the researches on feedrate planning and interpolation are extremely important.Analysis for the types of five-axis machines is firstly introduced, and the forward and inverse kinematics of the TRT type configuration are derived. There exist various kinds of problems in current five-axis CNC system, such as nonlinear error, nonlinear kinematics and dynamics limits, low efficiency in feedrate control, and so on. To solve these problems, feedrate optimization and interpolation algorithm for continuous path with small line segments are proposed in this thesis. In the respect of feedrate optimization, the feed limits in WCS are deduced based on the kinematics of the machine. Applying linear acceleration/deceleration, the constraints on the feedrate are formulated subsequently. Considering these constraints, the solution for the approximate optimal feedrate is proposed based on the critical point to achieve the goal of feedrate maximization. In the respect of interpolation, two kinds of minimal error based transition approaches are introduced, and the corresponding error models are constructed. A completed interpolation approach is proposed eventually.At last, all of these algorithms are verified in five-axis machine with TRT type configuration, and experiments indicate their validities. The proposed algorithms can be easily applied into other types of five-axis CNC system to improve their performance and machining efficiency.