Application Of ACC/DEC Interpolation Algorithm In Turbine Blade And Cutter Compensation Research

Turbine blade is a key part of steam turbine, it is one of the major indexes to measure the design level of the steam turbine machining technology. In order to improve the efficiency of the steam turbine, the surface of blade is more and more complex, processing technology methods are constantly updated, the blade precision processing is more and more strict. Due to the precision and quality of the blade precision processing directly affect the operation of the unit efficiency and safety reliability, so how to increase the machining accuracy and efficiency of the blade is an important topic.To satisfy high speed and high precision machining for steam turbine blade, an improved acceleration/deceleration (ACC/DEC) interpolation algorithm based on the NURBS curve was proposed as the blade curvature radius changed greatly. The interpolation algorithm in this paper considered the easily overrunning chord error and maximum acceleration, and used ACC/DEC control in the interpolation of feeding speed mutations sensitive area, it makes the feed speed meet the ACC/DEC demand and adjust with the curve curvature changes. So it improved the contour machining precision and reduced the impact on machine significantly. The experimental results proved that the interpolation algorithm can not only ensure the processing efficiency and precision, but also realize the smooth transition of speed.This paper presents an algorithm for the offsetting of NURBS curve/surface based on explicit matrix expression. Different from the widely used approximation methods, our methods deduce the matrix expressions of cubic NURBS curve and bi-cubic NURBS surface explicitly. Then based on the matrix expressions, the unit normal vectors of the progenitor curve/surface is computed precisely. At last the offset curve/surface can be obtained by directly offsetting the progenitor curve/surface in the unit normal vector direction with the required distance.