载重汽车用直齿轮冷挤压组合凹模的优化设计

Optimization design of cold extrusion combined die for spur gear of camion

为提高载重汽车用直齿轮冷挤压组合凹模的使用寿命,以组合凹模的齿形腔等效内径、直径比和过盈系数为设计变量,以降低模芯内壁等效应力为优化目标,建立组合凹模结构参数与等效应力的Kriging模型。应用Kriging模型结合粒子群算法,在可行变量空间内寻优,得到组合凹模最佳结构尺寸为:模芯外径D_2=107.485 mm,中圈外径D_3=187.215 mm,外圈外径D_4=274.839 mm,模芯与中圈的单边径向过盈量U_1=0.134 mm,中圈与外圈的单边径向过盈量U_2=0.253 mm,采用优化后的组合凹模进行数值模拟。研究结果表明:在模芯消气带齿槽处等效应力最大,其值为1 870 MPa。优化方法为齿类零件冷挤压成形组合凹模设计提供了定量的确定方法。

In order to improve the service life of cold extrusion combined die for spur gear of camion, the equivalentdiameter of tooth shaped cavity, diameter ratio and shrink fitting ratio of combined die were taken as design variables, theKriging model of effective stress and structure parameters of the combined die was built, which aimed at decreasing theeffective stress of the die insert. The Kriging model combined with the particle swarm optimization were used to find theoptimal structure size of combined die in the variable space. The optimal structure sizes of the combined die were asfollows： die insert diameter D2=107.485 mm, middle layer diameter D3=187.215 mm, stress ring diameter D4=274.839mm, unilateral radial shrink fitting between die insert and middle layer U1=0.134 mm, unilateral radial shrink fittingbetween middle layer and stress ring U2=0.253 mm. Meanwhile, the numerical simulation method was also used tosimulate the forming process with the optimized combined die. The results show that the maximum effective stress on theinside of die insert is obtained and the value is 1 870 MPa. The optimization method provides a method for the design ofcold extrusion combined die for gears.