The Research On Feedrate Scheduling Based On Curve Evolution

With the sculptured surfece parts have been widely applied in aerospace, mold manufacturing and other industrial fields, the requirements on machining efficiency and quality are higher and higher. As the key step of CNC, feedrate scheduling has aroused widespread concerns. It has a significant influence on the machining efficiency, stability and surface quality.Adaptive feedrate scheduling method has aroused widespread scholars’ research. Many methods meeting different working condition have been proposed in succession, and each algorithm for feedrate scheduling has its unique consideration Up to now, The feedrate scheduling method still exists many problems, such as the constraints are relatively single, the available methods for five-axis machining are limited,the methods based on constrained optimization model are difficult to calculate.In this paper, a curve evolution based feedrate planning method is proposed using proportional adjustment algorithm and curve evolution strategy. It takes various constraints in consideration at the same time. It is not only applying to three-axis machining, but also can be used in five-axis machining. Different from constrained optimization techniques, the proportional adjustment of feedrate sensitive regions is proved to suitable for simultaneously reducing the magnitudes of constraints such as axis accelerations and jerks. The feedrate profile with acceleration or jerk sensitive regions is capable of to be locally or globally deformed to target shape via a curve evolution strategy instead of the re-interpolation. In order to achieve more feiring feedrate curve,a smooth curve evolution method is proposed by incorporating a curve energy minimization into the curve evolution model The feedrate curve of each deformation is smooth through the feiring term adjustment.Simulations and experiments on an eight-shaped contour and a five-axis toolpath for flank machining are conducted. The results validate the effectiveness and reliability of the proposed method. Simulations of the proposed feedrate planning method are developed by VC++,and the final feedrate curve is satisfied the setting constraints. The five-axis flank machining experiment is performed. The actual axis velocity and the nominal ones have good agreements both in the shapes and magnitudes. It indicates that the proposed method has the ability to achieve a desired feedrate profile with various constraints. It is also helpful to improving the machining efficiency,accuracy and surface quality. In a word,the curve evolution based feedrate planning method provides a good solution rrethod for feedrate scheduling in CNC machining. It has important theoretical value and practical application value.