The Design Of U-shaped Benging Discharging Mode And Numerical Simulation Of Forming

With the development of modern industry, stamping has become an importantmeans of modern manufacturing, and occupies an important position in modernmanufacturing. Stamping processing not only has high production efficiency, materialutilization, but also the products of processing have high precision, good compatibility。And the U-shaped bending is a broad category of sheet metal stamping.While traditional used for stamping die design of U-shaped parts often exist thefollowing problems:(1) U-shaped part will not only spring back but also its thickness will change afterforming. Simply by the empirical formula of stamping die design, the products are oftendifficult to meet the requirements of design, and through the test mode method tomodify the mould structure is not only inefficient but also will cause certain economicloss.(2) Because rebound, parts after forming may be "hold" on the punch or card in theconcave die, so adopting which kind of unloading structure smoothly remove parts isalso the difficulty in the mould design.(3) If the designed unloading structure is not reasonable, the parts could not beremoved from the mold, or could be damaged, and the production efficiency would beaffected.In the paper, a kind of typical U-shaped part is as the research object, the formingprocess of u-shaped piece and bending the quality problems are discussed. In the designof the mould structure, mould compensation method is adopted to control spring back inthe U-shaped bending; the inversion of the mould structure is adopted to the situation ofU-shaped part difficult to remove from the mold on the basis of the typical bending die,and the press’s return force is used reasonably, then a set of simple structure andpractical discharge device is designed to remove the U-shaped part smoothly, rod lengthcalculation formulas are derived in the discharging device.After forming, sheet metal not only happens spring back, but also its thicknesschanges, while the change of thickness is often overlooked in most studies. With thedevelopment of computer technology and finite element method, finite element numerical simulation technology is a powerful tool in sheet metal stamping forming. Inthis paper, forming process and spring back situation of the U-shaped part are simulatedthrough the finite element numerical simulation software Dynaform, the distribution ofinternal stress and strain is analyzed in the sheet metal bending process, also thechanges of sheet thickness and part’s opening sizes are analyzed after spring back.Orthogonal analysis method is used to analyze the convex concave die clearance,friction coefficient, punch fillet rounded corners, and concave die fillet rounded cornerson the influence law of sheet thickness change and spring back through setting a groupof16simulation experiments and the stamping forming quality’s simulation ofU-shaped parts under combinations of different die structure parameter values, and a setof the optimal parameter combination is found to guide the design of the mouldstructure. Mould optimization result is verified through trial production mould andstamping U-shaped parts.