轴端长度对楔横轧阶梯轴成形光轴端面质量的影响

随着楔横轧工艺的不断创新与产品范围的进一步扩大,阶梯轴楔横轧成形光轴时,由于金属流动的不均匀性导致轴端长度直接影响着轧件轴端质量,从而降低产品的材料利用率。为探明其影响规律,提高轧件端部质量与楔横轧的材料利用率,本文通过DEFORM-3D有限元软件,采用数值模拟与轧制实验相结合的研究方法,对楔横轧阶梯轴成形光轴的轧制过程进行有限元模拟,通过分析轧制过程中的应力场、应变场及特征点,揭示轧制过程金属流动规律,阐明轧制过程变形机理；在此基础上,采用交互正交试验设计轴端长度、台阶倾角、台阶长度、断面收缩率4个工艺参数,分析这些参数对轴端凹心的影响关系,即凹心值与轴端长度、台阶倾角成负相关,与台阶长度、断面收缩率成正相关,且随着坯料轴端长度的减小最终轧件端部凹心逐渐增大。应用统计数据软件SPSS 22.0拟合获得各工艺参数与轧件端部质量的关系方程式,以凹心值为零为目标,获取了最优轴端长度对端部质量的影响方程式。通过轧制实验与模拟对比分析,获得的轧件形状和最终的端部凹心值基本一致,进一步验证了模拟分析的可靠性。本文获得的公式与端面质量的影响规律,可以有效地从理论上提高轧件端部质量,确定闭开联合楔横轧闭式轧制轴端长度,实现楔横轧无料头近净成形。

Effects of Shaft-end Length on the End-face Quality of Equal Diameter Shaft Formed with Cross Wedge Rolling from the Stepped Shaft

With the continuous innovation of cross wedge rolling technology, its product range is also expanding. When the stepped shaft is formed to equal diameter shaft by the cross wedge rolling, the quality of the shaft end is directly affected by its length due to the the inhomogeneous flow of metal. besides, the material utilization ratio is reduced. To obtain the better end-face quality and higher material utilization rate, it is necessary to study the influence rule in the cross wedge rolling process. The research studied rolling-forming process with numerical simulations on the DEFORM-3D finite element software and rolling experiments. Based on analyzing the distributions of the stress field, the strain field and the feature points, initially, the law of metal flow is revealed and the deformation mechanism of rolling process is clarified. Taking into account the complexity of influencing factors, it adopted the mutual orthogonal experiment in this paper designed on the four process parameters: shaft-end length, step angle, step length and cross-section shrinkage ratio. The influence of these parameters on the end concave was verified, that is: the concave value gradually increases as the step length and cross-section shrinkage ratio increase, while with the decrease of shaft length and step angle. Therefore, a smaller concave can be attained by reducing the shaft end length. The software SPSS 22.0 was used to analyzed statistical data, and the relationship equation between the process parameters and the quality of the shaft end-face was ascertained. With the concave heart value of zero as the goal, it also determined the influence equation of the optimum shaft-end length on end-face quality. By comparative analyses of the rolling test and the simulation, shapes of the rolled piece and concave values of the end-face were basically same, so the reliability of the simulation analysis was further verified. Theoretically, these influence rules and formulas can effectively improve the end-face quality of rolled piece, and determine the optimum length of the shaft end, achieving near net forming without material head in cross wedge rolling.