Three half-axis tool orientation optimization for spiral machining of blades

A regular three-axis computer numerical control (CNC) machine combined with an automatic indexing rotary table (AIRT) is always used to produce four-axis machining for blades in many medium-sized and small industries. Generally, AIRT has the characteristic of low precision, which often leads to obvious tool marks like overcut on the machined blade surface. To overcome this problem, a machining technique, named as {1}{2}-axis spiral machining method that uses the simplicity of three-axis tool positioning and the flexibility of four-axis tool orientation, is developed and implemented. Key issues are focused on transformations of tool orientations from four-axis to 1}{2}-axis and concrete contributions are twofold. First, universal principles are proposed to transfer tool orientations for general convex and concave surfaces. Second, with respect to the pressure and suction surfaces of blades in {1}{2}-axis spiral machining, a unified transformation method is also addressed in detail. A cutting test shows that overcut marks that easily occur in four-axis spiral machining can be effectively controlled by using the proposed {1}{2}-axis machining technique.