Research On Thinning Rule And Its Influencing Factors Of Medium Thick Plate V-shaped Bending

In recent years, the research of sheet metal formability has made a great development, mainly for cracking, wrinkling and springback.However, the studies at thinning of the 4mm or more thickness plate in bending forming are still not enough. The mobile of stress and strain neutral layer, thinning and its influencing factors during the bending of process remains to be further studied and solved. Theoretical analysis of thinning in existing literatures avoided to resolve the problem through ignoring or simple hypothesis. So, it's necessary to combine with the production practice, from the mechanical properties of material itself and the process of sheet metal bending thinning, then analyze the study on the bending process involved.This topic starts from the performance of experimental material firstly through the uniaxial tensile test. The test mainly involves that if the similarities and differences between the direction of material properties in 0°,45°and 90°have an affect on bending deformation or not. It obtains the yield strength, tensile strength, elongation, strain hardening index and plastic strain ratio of material. The result provides reference for the numerical simulation, bending test and data analysis.Carring through numerical simulation ofⅴ-shaped bending tests with DEFORM-3D according to the data of tensile test materials, and analysing the stress and strain can confirm that the neutral layer of stress and strain deformation in bending, and the middle layer always in the middle of the instantaneous plate thickness in the process of moving.In addition, using the module of point tracking can measure the specific thinning data ofⅴ-shaped bending deformation.Designing bending dies ofⅤ-shaped to carry on theⅤ-shaped bending test of medium thick plate, through changing materials, thickness, relative bending radius to discuss the rules and the influencing factors of plate bending thinning. The conclusions are:the quantities of bending thinning decreases with increment of relative bending radius. For different materials with the same thickness and bending radius, the thinning quantities increase as the increment of elongation and strain hardening and the diminution of yield ratio. For the same material with the same thickness, the quantities decreases with increment of relative bending radius, and for the same material with different thickness also follow the rule above, furthermore along the thinning rate decrease with the increase of thickness.