Research On NC Bending Forming Of Aeroengine 0Cr18Ni9 Thin-Wall Tube

Aeroengine is an important power component of the aircraft,and the engine pipeline is the lifeline connecting each functional area in the component.As the main part of the pipeline,there are very strict requirements for its processing quality.0Cr18Ni9 thin-walled tube is a typical part of engine external pipeline.Because of its small thickness diameter ratio,it is easy to produce quality defects such as bend cross-section distortion,wall thickness thinning and so on,which makes it difficult to process.In addition,the geometric shape of engine tube parts is usually diverse and complex,and its assembly density on the engine is very high,so its overall tube shape accuracy is very high.At the same time,parts collision often occurs in the process of tube NC bending,which leads to out of tolerance of forming dimensions.In order to ensure the precise forming of the tube parts,the interference of this kind of processing needs to be predicted in advance and the solution should be made quickly.In the aspect of quality control of bending,the process of bending is studied by finite element analysis.The results of forming limit diagram,stress and strain distribution of each group of tests were obtained by orthogonal test,and the influence of bending die design parameters on the forming quality of thin-walled tube was summarized.According to the above analysis results,the mold design parameters and corresponding processing parameters are given preliminarily.The bending forming results of each group of parts under the real processing conditions were obtained by subsequent process experiments.The results show that the die groove size directly affects the forming stability of the elbow;If the clearance between mandrel and tube is too large,it is easy to cause instability and deformation inside the deformation zone;The more the number of mandrils and balls is set,the higher the bending quality is,but the greater the forming resistance is.By comparing the finite element analysis results with the experimental results,it also shows that the finite element analysis results can effectively guide the setting of die parameters and process parameters,and realize the high-quality bending forming of0Cr18Ni9 thin-walled tube.In the aspect of precise bending forming,the main process parameters affecting the springback deformation of tube-bending are studied through experiments,and the influence rules of mandrel extension,compression force of die and bending rate on the springback deformation of tube-bending are mastered.After the reasonable setting of the above parameters,the bending springback law is studied.The results show that the springback angle of 0Cr18Ni9 is approximately linear with the actual bending angle.Based on the above springback law,a set of NC bending program correction scheme for bending angle and bending straight length is developed.The scheme is used to test the precise bending.Verify the feasibility and effectiveness of the compensation scheme for the correction of bending program.In the aspect of interference prediction in NC bending process,based on CAE motion simulation function module in UG environment,a set of mechanical motion simulation scheme for bending process is developed.Typical pipe parts are selected for numerical control bending mechanical motion simulation analysis,which verifies the effectiveness of the scheme for collision interference prediction in bending process.The research scheme can accurately predict the risk of interference and collision in the bending process of conduit parts,and then realize the rapid formulation of subsequent tube shape optimization scheme or bending process improvement scheme.