Research On The Law Of The Shape Distortions In Bending- Forming Withnarrow Sheet

This thesis is aiming at the research of shape distortion in bending processes with the narrow sheets. It starts with deriving the theoretical formula, then verified by finite element software. Finally, a series of forming tests were conducted for the comparison, the reason for shape distortion phenomena and its influencing factor were revealed, also the changing regularities were insight discussed.Firstly, the states of stress in bending process with narrow sheet were analyzed, and then the total theory of plasticity was adopted here, which established the relationship between stress and strain. Then the expressions of width variation in plastic region in bending process with narrow sheets were obtained. With these formulas, the influencing factors and changing regularities were analyzed. Some data were calculated by this formula under a special condition in order to comparing with finite element and forming tests.Moreover, the bending of narrow sheets was analyzed by using ABAQUS, and it confirmed the results of theoretical derivation. Meantime, the models were adjusted through the factors for theoretical derivation. The results illustrated the validity of theoretical formulas.Finally, the shape distortion of bending testing were analyzed. Traditional punches and a polyester rubber die were used to the bending tests, in order to verify both correctness of theoretical formulas and validity of simulations. Meantime, the reasons of inaccuracy and its magnitude were obtained. the influencing factors and changing regularities with narrow sheets in bending processes were obtained.Compared with results, work of this paper can provide experiences for theoretical arithmetic, FEM simulation and bending tests, and factors and regularity were summarized. It also serves as the basis for bending process design.