某型轿车门框三维拉弯模具设计方法研究

Research on design method of three-dimensional stretch bending die for doorframe of a car

为减少某型轿车门框的三维拉弯回弹,通过单向拉伸试验,获得了SPCC材料的弹性模量、抗拉强度、屈服强度、应变硬化模量等材料的力学性能参数和真实的应力-应变曲线方程。基于板料弯曲回弹计算,给出了拉弯件内层材料的回弹前和回弹后曲率半径的关系以及回弹半径的表达式。在此基础上,提出将工件形线离散化,计算工件回弹前的形线方法,确定拉弯模形线,并进一步绘制拉弯模外形。根据理论分析结果,设计门框的三维拉弯模具,进行拉弯试验,并得到了合格的工件,验证了该方法适用于拉弯模具的设计。

In order to reduce the three-dimensional stretch bending springback of doorframe of a car, uniaxial tensile test method was used to obtain the basic performance parameters such as elastic modulus, ultimate strength, yield strength, strain hardening modulus, etc. and true stress-strain curve equation for the SPCC material. The relationship between curvature radii of inner before and after springback and springback radius expression for stretch bending workpiece were given based on bending springback calculation of sheet metal. On the basis of analysis, a workpiece discrete method was proposed to calculate the shape line before springback, and the method was used to determine the shape line of bending die and further draw its shape. According to the results of theoretical analysis, the three-dimensional bending die of doorframe was designed, and the qualified workpieees were obtained by bending test. The results show that the method is suitable for the design of stretch bending die.