Research On The Polishing Of Complex Surfaces Of Titanium Parts With Elastic Wheels

Titanium alloy material, as a typical difficult-to-cut material, is widely used in aerospace and energy fields for its excellent mechanical properties. Due to extremely harsh environments, during machining titanium alloy parts, such as geometrically complex cavities and impellers, are required to have high surface quality and machining accuracy. However, constrained by the narrow machining space, interference often occurs when using abrasive belt polishing. In this case, these titanium alloy parts are often polished by manual operation and thus it will lead to inefficiency and low surface quality and weak processing consistency of parts. To realize the integration of milling process and polishing process, the polishing of complex surfaces of titanium parts with elastic wheels is investigated in this paper.First, a set of experiments of planar polishing are carried out using a combinative process mode of abrasive belt wheel, fleece flaps wheel and wool wheel. Three kinds of polishing path patterns are first chosen to compare the effect of removing milling marks in the polishing process with abrasive wheels. Thus, a optimum path pattern, namely Hilbert path, is finally determined and used to conduct the subsequent processing parameters experiments. Afterwards, the experiments of titanium plane polishing were conducted by the optimum process parameters, and the surface quality of the polishing samples was analyzed. The experiments results showed that the surface roughness was reduced from Ral.305um to Ra0.079μm, material removing depth during polishing was0.12mm, and residual stress reached-4.5MPa.Second, arc transition and unit stitching were adopted to improve defect during polishing with standard Hilbert. The calculation processes of arc transition and classification of stitching unit were given. Slotted abrasive wheel was used for complex surface polishing, instead of traditional abrasive wheel. The fit performance of abrasive belt wheel with curve surface was analyzed, and the combinatorial deformation of abrasive belt was proposed.Third, according to the parameter mapping, surface polishing path was obtained by two-dimensional Hilbert curve mapping. The constraints and calculation methods of spacing were given by analyzing the relationship between depth and spacing. Calculation method of tool axis vector was given according to the two-point offset of cylindrical milling cutter milling undevelopable ruled surface. The feasibility of surface polishing path generation method was verified, and the improved polishing path was compared with the original one. Finally, the polishing experiments of complex surface of titanium parts based on the milling-polishing integration ideas were conducted. Ball-end cutters were used to mill a undevelopable ruled surface sample and a blade thin-walled part. The polishing experiments of Hilbert curve path with elastic wheels were conducted on five-axis CNC milling Center. The Results showed that the milling veins of polished surface were not visible, and the roughness of the sample was reduced from Ral.425μm to Ra0.2μm-0.25μm...