Research On The Milling Process Optimization Of The Aero-engine Combustor Case

As a key structure of aero engine,the combustor casing is the base of the whole combustor.In order to withstand the high temperature,high pressure airflow and various complex alternating loads generated in engine,the casing materials generally choose nickel-based alloy materials which is hard for machining.In addition,due to the particularity of casing function and the need of weight reduction,its thinnest wall thickness is generally no more than 4mm,which has the characteristics of low rigidity and high material removal rate in the manufacturing process.Therefore,how to high efficiency,high quality and low cost machine combustion casing has been a difficult problem for aviation industry.Based on the efficiency,quality and cost problems encountered by an enterprise during the combustor milling process,this paper optimizes the milling process.Firstly,the existing machining milling process in enterprises is analyzed and the problems that need to be improved are found.Then,the process optimization method is studied from the aspects of process division and process route determination,tool system,deformation control and finish machining fixture to solve these problems.Based on UG and VERICUT computer-aided manufacturing software,the detailed implementation process plan was developed,and the tool selection,fixture design,path planning of UG CAM and simulation analysis of CNC milling were realized.The specific optimization content includes the following five aspects:(1)The rough milling process is separated from the original milling process as an independent process,and the lower cost four-axis machine is used to replace the five-axis machine in the rough milling process to reduce the factory investment.At the same time,remove the case from the fixture after rough milling in free deformation result in eliminating the residual stress.(2)Design special shaped carbide mill to cut 10 rectangular cavities on ID,short the milling path to reduce the cutting time.(3)Use angle head instead of long hydraulic straight holder as the holder system to cut 18 square cavities on ID,this increases the rigidity of the cutter system and reduces the ball mill usage.(4)The high speed ceramic milling technology is introduced in the rough milling process,which greatly reduces the cutting time.(5)Redesign the fixture,add the supporting jig to increase the part rigidity and reduce the vibration during machining.Finally,the optimized milling process is verified through experiments.The experimental results show that the optimization achieves the purpose of reducing the manufacturing cost,reducing deformation and improving efficiency,and the expected effect of the enterprise is achieved.In addition,the research results can also be extended to the process optimization of other aero-engine parts.