Research On Shape Warpage Of Curve Flanging Parts And Relevant Design Principles

As one of the most widely used forming processes in the sheet metal forming process,the rubber sac forming process has been recognized by domestic and international aviation manufacturers for its excellent forming quality and reliable quality assurance.In the past long-term production process,the hydraulic rubber sac forming parts often have some shape distortion phenomenon,the appearance of warpage will not guarantee the precision requirements of the forming parts.The warpage shape of sheet metal parts can seriously affected the quality of the flange parts,the warpage degree of the rubber sac forming part has seriously affected the assembly work of the aircraft structure parts.In this paper,the PAM-STAMP finite element simulation software will be used to simulate the active deformation and the unloading process of the "one step" flanging part of the sheet metal parts.Measure the warpage of each marking angle position of the sheet metal parts after forming,obtain warpage height distribution,and the shape of the curve flanging mechanism of warpage will be deeply analyzed.This paper proposes to analyze the influence of curve flange shape warpage by changing the geometric parameters,and use the actual sheet metal forming parts of the experimental verification to prove the reliability of finite element analysis.The test results show that the warpage of the curved flanks is proportional to the springback degree of the flanging parts;for the influence of geometric factors on the warpage,change the circle center angle,the results show that warpage and central angle is proportional to the relationship,the radius size of the punch fillet is proportional to the warpage degree;465-333,765-633 and 1065-933 three kinds of variable curvature parts are shown in this paper,the results show that the raise of radius of curvature is proportional to the change of warpage height after forming.For the design principles of aviation sheet metal parts,referencing to the China Department of Aeronautics and Astronautics on the tolerance of aircraft sheet metal parts,it is found that for the blank 465-333,the maximum angle of the basic dimension limit deviation of the standard first level in the file HB6470-90 is 4°,the maximum angle to meet the limit deviation of the second level basic size is 9°,the maximum angle to meet the limit deviation of the second level local size is 74°;for the sheet metal parts with 60 degrees of center angle,the maximum radius of curvature to meet the limit deviation of the second level basic dimension is 585-453.The above research results have important significance in guiding the rubber forming process of aviation sheet metal parts and improving the product quality.