直齿圆柱齿轮双向镦挤精密成形工艺对比研究

为实现直齿圆柱齿轮精密成形,并克服传统工艺存在的成形力大、模具结构复杂等一些不足,在已有齿形凸模双向镦挤成形直齿圆柱齿轮的基础上提出了另外2种改进的成形工艺,分析了不同成形工艺下端面摩擦力对载荷的影响,利用有限元模拟软件DEFORM-3D分别对3种成形工艺进行了数值模拟研究,并提出了一种优化的成形新工艺——无齿凸模双向镦挤精密成形.结果表明:采用无齿凸模镦挤成形直齿圆柱齿轮在载荷及模具结构方面优于有齿凸模镦挤成形,其中,无齿凸模双向镦挤较有齿凸模双向镦挤,上、下凸模载荷下降约55%;无齿凸模双向镦挤较非对称凸模双向镦挤,上、下凸模载荷分别下降约50%、38%;无齿模具加工制造更容易,强度更高;新工艺的等效应力最大值为3种方案中最小,而且等效应力变化正常,无破坏现象出现.对优化后的成形工艺进行了试验研究,得到了齿形轮廓清晰、充填饱满、无折叠、开裂等缺陷的铅质试件,试验结果与模拟结果基本吻合.

Comparative study on the processes of two-way upsetting-extrusion precision forming of spur gears

This paper aims to realize spur gears precision forming and overcome the deficiencies of traditional processes such as large forming force and complex mold structure. Two kinds of improved forming processes were proposed based on the existing spur gears forming of two-way upsetting-extrusion with tooth shape punch. The influence of friction on load under different forming processes was analyzed. The numerical simulation study of three kinds of forming processes was carried out by using the finite element simulation software DEFORM-3D. It was proved that forming spur gears with toothless punch was superior to that with tooth shape punch in load and die structure, in which the load value of upper and lower punch of two-way upsetting-extrusion with toothless punch was decreased by about 55% compared with that with tooth shape punch. The load values of upper and lower punch of two-way upsetting-extrusion with toothless punch were decreased by about 50% and 38% compared with that with asymmetrical punch, suggesting that the manufacture of toothless punch is easier and with higher strength than tooth shape punch. The maximum effective-stress of the new process was the smallest among the three schemes, and the change was normal with no destructive phenomenon. Thus an optimized two-way upsetting-extruding precision forming process with toothless punch was proposed and studied. A test-piece with clear tooth profile, full filling, no folding, and no cracking was obtained in the experiment, and the results were basically consistent with the simulation results.