Research On Key Technology To Increase NC Milling Efficiency Of Al-Alloy Impeller

As the key part of mini-type turbine engines,the demand for Al-alloy integral impeller has been increasing in recent years along with the development of economy and our national defense. However, how to increase the production efficiency of Al-alloy integral impeller has been a major problem of industry and academia. From the perspective of optimization of manufacture parameter and application of 5-axises milling, this paper aims to do research on key technology to increase NC milling efficiency of Al-alloy impeller. Based on the theoretical analysis and experiments, the manufacture efficiency of this type of integral impeller was increased a lot.Main works and achievements of this paper were shown as follows:1. The cause of error of the 5-axises machining process was analyzed. The standard of feed distance and pick distance was given out based on it. A un-interfere tool path was obtained via tool vector control algorithm. 5-axises NC program was produced by UG. A drive surface was built. Swarf Drive method was used while NC program was built. The tool change value was set 3 degree at the edge of blade. A VERICUT simulation and an experiment were done. A qualified blade was obtained.2. A private clamp was designed and produced. Kistler dynamometer was used to measure the cutting force of 4-aixses and 5-aixses blade machining process. Results showed that cutting force fluctuation was bigger while blade was machined with 4-axises. Cutting forces of 5-axises were comparatively smooth. Resultant cutting forces of both taken on a tendency increased first and then decreased with cutting speed increased.3. The change of blade modal was investigated by experiment and FEA simulation while material removal. Two grade modals in the area could be detected by sensor. The frequency of modal went up at first, and then went down with the material removal. Modal shape was not change with the removal. Based on the theory of Altinas, the influence of stock removal to the Lobes was researched and 3-D Lobes were built. Some cutting experiments were done to validate the 3-D Lobes.4. Surface roughness Ra decreased with the decrease of feed and with the increase of cutting speed. Surface texture changed with feed. It looked like a honeycomb at first and then a rectangle later, with the decrease of feed. Longitude mark vanished with the decrease of feed, at last. Surface topography reflected the same tendency. Surface hardness was higher than base. The max value of work hardening capacity was 22.5%. The thickness of affected layer was between 5μm and 10μm that measured under SEM had the same tendency of hardness. There was no defect in the layer.5. Compared with 4-axises, there were natural advantages when 5-axises machining was used. There was almost no invalid path while cutting with 5-axises compared with 50% invalid while milling with 4-axises. 5-axises milling is more efficient than 4-axises under the same cutting parameters. What's more, the upper limits of 5-axises is higher than 4-axises machining. Manufacture route was optimized to improve the machining efficiency. The machine of fluting and blade surface milling was changed. 5-axises NC program replaced 4-axises at same time. The manufacture efficiency of integral impeller was increased 50% under the synthesis action of these works. The expert system of cutting parameter on machining Al integral impeller was designed and realized.