为探究轨道用中空薄壁大小幅铝型材的挤压规律，采用HyperXtrude仿真软件对型材的挤压过程进行了详细的数值模拟，分析模具结构和工艺参数的影响，并对比了2个形状相似的大幅型材和小幅型材的成型规律。结果表明：在模具结构方面，焊合室与引流槽对大小幅型材的影响最为明显，其中焊合室的变化对小幅型材的最大变形量有更明显的降低效果，降幅达42.82%，而大幅型材的降幅为25.34%；引流槽的变化则表现出不同的影响趋势，引流槽变化后，大幅型材的最大变形量降幅为40.88%，而小幅型材的为24.72%，其原因是小幅型材的引流槽较短，大幅型材引流槽的修改则更为复杂，故引流槽变化对大幅型材的影响更为显著。在工艺参数方面，分析了不同条件下型材金属变形量、金属流速和型材出口截面流速均方差的变化，发现挤压速度和模具温度对大幅型材的影响更为显著，而坯料直径对小幅型材的影响更为显著。该文研究结果为优化铝型材的挤压工艺提供了理论依据。

In order to explore the extrusion law of large-scale and small-scale hollow thin-wall aluminum profiles for rails, simulation software HyperXtrude is used to numerically simulate the extrusion process of the profiles, the influences of mold structure and process parameters on the extrusion are analyzed, and the forming rules of two large-scale and small-scale profiles with similar shapes are compared. The results show that, in terms of mold structure, the modification of welding chamber and drainage groove has the most obvious influence on large-scale and small-scale profiles, for instance, the change in welding chamber significantly reduce the maximum deformation of the small-scale profile, with a reduction of 42.82%, while that for the large-scale profile is 25.34%. The change in drainage groove structure shows different impact trends—after altering the drainage groove, the maximum deformation reduction of the large-scale profile is 40.88%, while that of the small-scale profile is 24.72%. The drainage groove of small-scale profile is relatively shorter, and the modification of the drainage groove of large-scale profile is more complicated, so that the change of drainage groove has a more significant impact on large-scale profile. Moreover, in terms of process parameters, according to the changes of metal deformation, metal flow rate and the SDV values of the profile exit section under different conditions, it is found that the extrusion speed and the die temperature have more significant impact on the large-scale profile, while the billet diameter has a more pronounced effect on the small-scale profile. This research provides theoretical support for optimizing the extrusion process of aluminum profiles.