Abstract: In view of uneven allowance and rough surface of traditional equal height stratification for rough milling, a gradual hierarchy process method was proposed. As the model established by T-spline surface has unified parameter domain, an improved variable distance offset method was used to define the rules of surface deformation, and a series of deformation surface sequences were obtained. The cutting depth, tool radius and other machining parameters were used as constraint conditions so as to get the sequence of processing layers. By planning the tool path of each layer, the whole tool path of gradual hierarchy process which was based on the surface deformation was obtained. Based on VS2010 and Open GL, a simulation module was developed to verify the simulation, and the methods were checked by the actual machining. The results show that the machining allowance is more uniform and the surface is smoother.

Key words: surface deformation, gradual hierarchy process, T-spline surface, tool path, simulation