摆线液压马达内花键输出轴冷锻成形工艺与模具研究

目的 为了提高摆线液压马达内花键输出轴零件的加工效率及材料利用率、降低生产成本，提出一种冷精密成形的工艺与模具。方法 首先分析了摆线液压马达内花键输出轴的形状特点，初步制定了三工序冷挤压成形工艺:正挤细杆—反挤深孔—反挤花键孔，并通过数值模拟和实物实验对该成形工艺进行分析验证。在工艺实验中发现，采用线切割方法加工的第3序通体花键形状冲头，在与冲头套下端面交界处极易发生断裂。因此对花键冲头的结构和加工方法进行了调整，将冲头整体设计为圆柱台阶状，头部采用电火花加工方法加工一段花键形状，花键与圆柱部分采用锥角过渡。结果 实验结果显示，锻件成形工艺稳定，成形锻件精度较高，改进后的冲头寿命较高。结论 内花键输出轴成形工艺可行，改进的冲头结构降低了冲头产生应力集中的风险，提高了抵御偏载力的能力，成形工艺与模具满足了批量生产的考核。

Cold Forming Process and Die for Internal Spline Output Shaft in Cycloid Hydraulic Motor

In order to improve the processing efficiency of the internal spline output shaft in cycloid hydraulic motor, increase the utilization rate of materials and reduce the production cost, cold precision forming process and die are proposed. First,the shape characteristics of the internal spline output shaft in cycloid hydraulic motor were analyzed, a three-step cold extrusion process was preliminarily formulated:direct extrusion of thin rods, indirect extrusion of deep holes, indirect extrusion of spline holes. The feasibility of the forming process was verified by numerical simulation and real experiment analysis. In the process experiment, it was found that the third-step spline shaped punch machined by the wire cutting method was prone to fracture at the lower end face of the punch sleeve. Therefore, the structure and machining method of the spline punch was adjusted. The overall punch was designed as a stepped cylindrical shape, its head was machined by the EDM method as a spline shape, and the spline and cylindrical part adopted taper angle transition. The experimental results show that the forging process is stable, the forging precision is high and the life of the improved punch is long. The forming process of the inner spline output shaft is feasible, the improved punch structure reduces the risk of stress concentration and enhances the ability to resist the unbalanced load. And the forming process and mold life have passed the mass production assessment.