目的 针对长方体（正方体）自锁底纸盒成型过程中粘合余角底面容易出现卡滞、破损的现象，研究其自锁底纸盒粘合余角底面的切点轨迹。方法 集中研究长方体（正方体）自锁底纸盒的粘合余角底面在成型过程中的切点在三维坐标中的轨迹问题，确定参数轨迹方程为正弦函数曲线。结果 不论长方体的长和宽是否相等，自锁底纸盒粘合余角底面的切点轨迹都是正弦函数曲线。结论 该正弦函数曲线的设计可以避免自锁底纸盒成型过程中出现的卡滞和破损现象，同时使自锁底粘合纸盒的盒底设计更加合理。

The work aims to study the point trajectory at the bottom of adhesive coangle of auto end-lock box regarding the clamping stagnation and damage occurring at the bottom of adhesive coangle in the process of forming cuboid (square) auto end-lock box. The study was concentrated on the point trajectory in the 3D coordinates at the bottom of adhesive coangle in the process of forming cuboid (square) auto end-lock box, so as to determine locus equation of the parameters as sin curve. No matter whether the length and width of the cuboid were equal, the point trajectory at the bottom of adhesive coangle of the auto end-lock box was sin curve. The design of such sin curve can avoid clamping stagnation and damage occurring in the process of forming auto end-lock box and enable the design of the bottom of the auto end-lock adhesive box to be more rational.