| Small-curvature and ultra-thin-walled AISI304 stainless steel bellows components were widely used in automobile engine exhaust components due to their excellent performance in weight reduction,vibration reduction,and corrosion resistance.The ultra-thin-walled bellow tube was prone to forming defects when the process parameters were not set well,and the forming was extremely difficult.Therefore,3D finite element model of AISI304 stainless steel tube bending was built.During the bending process,the stress was mainly concentrated near the tangent point of the bending tube.When the bending angle was less than 60°,When the bending angle was greater than 60°,the bending tube enters the stable bending stage,and the maximum increase of the stress and strain decreases.After the mandrel was pulled,the bending stress of the bending tube reduced by more than 16%.When the bending angle was 180°,the tensile stress of the tube reduced by 26.6%.The springback angle of the tube gradually increased with the increasing of the bending angle of the tube around the bending,metedθ?=0.0174θ-0.2336 functional relationship.A springback compensation formulaθ=1.0177θ′+0.2377 was proposed.When the bending angle was less than 60°,the springback radius changed rapidly.After the bending angle was greater than 60°,the decline of the springback radius in accordance with?R=51.92 07θ-0.8063functional relationship.The bellow was elongated by 1.98 mm when the boosting speed was 110%of the tangential linear velocity of the neutral layer;The forming quality was best when the gap between the tube and the die was 0.05 mm;When the friction coefficient of the die was0.05,The severe wrinkling would occur at the position close to the clamping die of tube,and the other tube-die friction coefficients have little effect on the forming quality.When the number of balls was less than 5,which results in a large cross-sectional distortion of the bending deformation area.Figure 67;Table 3;Reference 48... |
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