NURBS Interpolation Algorithm to Minimize Chord Error in 5-Axis CNC Milling Operations of Turbine Blades

Abstract

5-Axis CNC machining operations are added to create complicated items with free form surfaces, such as turbine blades. Virtual machining systems are used in machining processes to improve the precision of manufactured products. Chord errors can be caused by cutting tool paths with a set feed rate in 5-Axis machining processes of turbine blades with free form surfaces. As a consequence, chord errors should be studied and eliminated in order to obtain the appropriate precision in machined products with free form surfaces. The research work proposed a virtual machining system to reduce chord error in 5-Axis milling of free form surfaces. To obtain the NURBS (Non-Uniform Rational B-Splines) profiles of cutting tool paths with abilities of control points modification along machining operations, the curved surface interpolation algorithm during turbine blade five axes milling processes is implemented. Then, a NURBS interpolation algorithm with restricted chord error and control of acceleration is developed in the study to minimize chord error in machined parts with free form surfaces. Finally, the sample turbine blade is machined by using the 5-Axis CNC milling and the chord error along machining paths are measured by using the CMM machine. As a consequence,, the proposed virtual machining system can provide an efficient device for boosting the machined components accuracy with free form surfaces by employing 5-Axis CNC milling machines.