A nonuniform offset surface rigidity compensation strategy in numerical controlled machining of thin-walled cantilever blades

It is difficulty to produce high quality thin-walled cantilever blades in numerical controlled(NC) machining due to cutting force induced workpiece deflections which result in surface errors on the machined blades. The methodology presented in this paper aims to compensate the rigidity of blades for induced surface errors in finish machining by modifying the machining allowances in the rough/semi-finish NC machining procedure. To ensure this, a nonuniform offset surface is introduced. First, the influence of cross-sectional thickness on the deflection of thin-walled plates under concentrated forces is discussed. Second, linear and sinusoidal functions are adopted to plan the uneven offset values for the nonuniform offset surface respectively along the radial and cross-sectional direction of the blades. Finally, based on the primary cross-sectional curves, the nonuniform offset surface is constructed by lofting. The experimental results show that the nonuniform offset surface can improve the rigidity of the test blades in finish machining, and the test blades machined this way can meet the design requirements.