Research on shaping of burr less gear by cold extrusion through reducing after expansion workpiece diameter

当在限制工件外径的同时挤压齿轮时，尽管压力（载荷）低，但在成形形式的端面上出现毛刺状的不规则性。当在扩大工件的内径的同时挤压齿轮时，端面上的不规则性变小，但载荷变大。为了发挥两种方法的各自优点，采用先膨胀后挤压的工艺进行了成型实验。其目的是在低载荷下获得具有小毛刺状不规则性的成形形式，并最终仅使用冲压线生产齿轮。首先，发现可以使用上述方法形成齿轮。确定了获得有利齿轮的横截面积减小的下限。冲头、芯轴和冲模所需的压力远低于冲头、芯轴和冲模材料的强度。11与两步挤压法相比，端面上的毛刺状不规则尺寸可以减小，但不能完全消除，发现由于尺寸减小，可以用压力机矫正。

When extruding a gear while confining the outer diameter of the workpiece, burr-like irregularities occur on the end surface of the shaped form although the pressure(load) is low. When extruding a gear while expanding the inner diameter of the workpiece, the irregularities on the end surface become smaller but the load becomes greater. A shaping experiment was conducted in this study to take the respective advantages of the above two approaches by adopting a procedure of extrusion after expansion. The intention was to obtain a shaped form having small burr-like irregularities with a low load, and eventually produce gears using only a press lineFirst, it was found possible to form gears using the above method. The lower limit of cross sectional reduction in area to obtain a favorable gear was determined. The needed pressure of the punch, mandrel, and die is far below the strength of the punch, mandrel, and die materials. The burr-like irregularities on the end surface could be reduced in size compared with the two-step extrusion method, which has been proposed for gear shaping, but could not be eliminated completelyIt was found that the irregularities could be rectified with a press machine because of their reduced size