The Tool Path Planning of Composed Surface of Big-twisted Blisk

Abstract

To solve the problem of the difficulty in tool path planning of big-twisted blisk in five-axis CNC machining, a composed surface processing method was proposed in this paper, taking the blade and flow channel as a whole composed surface to plan the tool path. At first, the tool was feed from the edge of air intake and exhaust respectively, processing along the blade from top to the root, and transiting to flow channel, then to the root of the adjacent blade and coming out from the top in the end, which avoids the problem of tool deformation caused by using long tool in the traditional helix method. The tool path of the composed surface was planned by adopting partition method, which is to divide the composed surface into the blade area and the flow channel area, and planned the tool path respectively. For the blade area, it is divided into the blade body area and the blade edge area. The blade body area adopted iso-parametric method; and since the edge of the blade is thin and the curvature of which changes dramatically, a geodesic distance method was proposed in tool path planning to avoid the abrupt change of tool direction. For the flow channel area, a cross-section method was proposed to connect the tool path of the adjacent blade, ensuring the smooth transition of the tool path and avoiding the problem of the machining area which cannot be completely covered by using geodesic distance method. Finally, based on Rhino software platform a corresponding CNC module was developed in the way of secondary development, and a continuous tool path was generated.