拉伸矫直数学模型及试验验证

Mathematical Model of Tension Straightening Process and Its Experiment Validation

拉伸位移是拉伸矫直工艺中极为重要的工艺参数,建立拉伸矫直过程拉伸位移与拉伸力的数学模型是科学确定矫直工艺参数的基础。根据拉伸矫直过程中拉力的变化规律,将拉伸矫直分为弹性加载第一阶段及其回复阶段、弹性加载第二阶段及其回复阶段、弹塑性加载阶段。以一维弯曲的圆形截面棒材为研究对象,假定矫直为线性强化材料,依据弹塑性力学理论,推导建立了拉伸矫直过程的拉伸位移——拉伸力数学模型。以AZ31镁合金棒材为例,采用该数学模型进行实例计算的结果与试验结果吻合较好。研究表明,原始挠度通过影响弹性第一阶段的斜率,从而影响卸载后的弹性回复量。当其他条件不变时,随原始挠度增加,矫直所需的拉伸位移和拉伸力均增加。

Displacement is a very important technological parameter in the tension straightening process.Building the mathematical model to illustrate the relationship between the displacement and tensile force is a basic research on determination of the technological parameter of tension straightening process.The tension straightening process consists mainly of the elastic loading I and unloading stage,the elastic loading II and unloading stage,the elastic-plastic loading stage on the basis of the change rule of tensile force.The circular bar of one-dimensional bending is selected for study and is assumed to be linear strain-hardening elastic-plastic material.Based on the elastic-plastic mechanics theory the mathematical displacement-force model of tension straightening process is established.The AZ31 magnesium alloy rod is taken as an example,the result of calculation by the displacement-force model is in good agreement with the experimental result.The research shows that the initial deflection has effect on the spring-back after unloading by influencing on the slope of elastic loading I.The displacement and tensile force needed for straightening increase with the increasing of initial deflection when other conditions remain unchanged.