V形弯曲时弯曲线挠曲变形及解决措施研究

Study on flexural deformation of bending line during V-shaped parts bending and its solutions

针对V形部件弯曲加工时出现的挠曲变形问题,基于材料力学和金属塑性成形理论,分析了V形部件弯曲变形区内单元体的应力、应变分布,并结合V形部件实际受力和变形情况,确定弯曲线挠曲变形成因、力学模型和影响因素。通过对不同长度、材质、厚度、角度的V形部件的弯曲试验验证了研究结果的正确性。结果表明:V形部件弯曲线长度方向和材料厚度方向的塑性应变符合材料力学弯曲应力-应变理论,且沿弯曲线长度方向上对应点应变均布;材料力学的均布载荷简支梁力学模型和挠曲线方程适用于V形部件弯曲线挠曲变形;V形部件弯曲线挠曲变形的挠度值与内应力、V形部件长度成正比,与材料的弹性模量、V形断面对中性层的惯矩成反比;V形弯曲变形程度大时,产生的内应力大,弯曲线挠曲变形大,反之则弯曲线挠曲变形小。最后,提出了通过提高部件惯矩、在模具上给出反变形等办法来解决V形部件弯曲线挠曲变形问题,从而提高产品质量。

Based on the mechanics of materials and metal plastic forming theory,the stress and strain distributions of element in bending deformation zone of V-shaped parts were analyzed to solve the flexural deformation produced during bending process of the V-shaped parts.Combined with the actual force and deformation situation of the V-shaped parts,the reason,mechanical model and influencing factors of flexural deformation for bending line were determined. The correctness of the research was verified by the bending test of V-shaped parts with different lengths,materials,thickness and angles. The results show that the plastic strain rules in the direction of the bending length and the thickness direction of the V-shaped parts conform to the material bending stress-strain theory,and the corresponding points of strain in the direction of the length are uniformly distributed. The mechanical model of simply supported beam with uniform load and the flexural equation are suitable for the flexural deformation of bending line for V-shaped parts. The deflection values of the flexural deformation of the V-shaped parts are proportional to the internal stress and the length of the V-shaped part,but inversely proportional to the moment of inertia of the V-shaped section to the neutral layer and elastic modulus of the material. The flexural deformation increases with the increase of internal stress induced by larger deformation degree of V-shaped parts,on the contrary,it decreases. Therefore,the methods to solve the flexural deformation of bending line for V-shaped parts and improve the quality of product,such as improving the moment of inertia of parts and applying reversede formation on the die,were put forward.