The Key Technology Research Of Closed Impellers Multi-Axis Milling

Impeller is an important part in many products such as turbine steam, turbine, engine and fan, etc, and is used to pressurized and transform energy for the gas or liquid which flow through. Closed impeller is gradually finding widely applications in defense, energy and some basic industry due to its superior performance. The manufacturing of closed impellers is always one of the difficult problems in the field of machinery manufacturing, and multi-axis milling is the mainly manufacturing method. With the development of 3D printing and other advanced manufacturing technology, the manufacturing technology for closed impeller has also been broadened. The closed impeller studied in this paper has complicated geometrical structure, weak blade and hard-to-machine blade material, so the main bottlenecks of using multi-axis milling is the bad accessibility and cutting deformation.Aim at high efficiency and precision multi-axis milling of closed impeller, the following contents were studied:(1)Efficient multi-axis milling processBased on the analysis of geometry structure and material properties for closed impeller, and considering it is a thin-wall parts, by using finite element analysis of cutting system, a control method of cutting deformation was proposed, an innovative processing strategy was presented, and the reasonable process parameters was determined, which contributes to the improvement of machining efficiency and quality.(2) Optimization control of tool axis vectorSince Closed impeller has narrow channel and large vane curvature variation, the interference between the tool and workpiece can be avoided effectively by controlling the tool axis vector. At the same time, the mutation of tool axis vector was avoided through the optimization of tool axis vector, and the process of multi-axis machining will be more stable and smooth, bringing in high machining quality and efficiency.(3) Virtual manufacturing technology of closed impeller.By studying the virtual manufacturing technology of closed impeller, a virtual manufacturing system based on a five axis machining center DMG125P was built up, and overcutting and collision existing in practical manufacturing process was avoided effectively though the built system.(4) The above contents were verified though multi-axis milling of closed impeller and the curve line of closed impeller was detected using three coordinate measuring machine. The results showed that curve line error meets the design requirements. Hydraulic performance test also indicated that the hydraulic performance indexes have been greatly improved.In this paper, based on the study of high efficiency and high precision multi-axis milling of closed impeller, related technologies were summarized and collated into technical specifications to provide technical support for manufacturing of closed impeller parts.