扩隅凹模精密成形直齿圆柱内齿轮试验研究

Experimental study on precision forming of spur cylindrical internal gear with expansion die cavity

为解决内齿轮塑性成形工艺中存在的角隅填充困难及成形力大等问题,在已有的扩腔凹模成形柱形齿轮的研究基础上进一步探索直齿圆柱内齿轮的扩隅凹模精密成形工艺。以模数为3 mm,齿数为18,外径为Φ80 mm的直齿圆柱内齿轮为研究对象,利用DEFORM-3D有限元软件和设计制作的试验模具对新成形工艺进行了数值模拟和物理模拟试验研究,初步探讨了扩隅空间几何参数(扩隅斜角α、扩隅空间齿宽方向尺寸b和扩隅空间齿高方向尺寸h)对内齿轮成形效果的影响。研究表明,新工艺成形载荷较闭式模锻工艺可降低约70%;α或(b,h)值越大,镦压成形力越大,而顶出成形力越小,角隅填充更加饱满,当α或(b,h)值过大时,内齿轮下角隅产生废料,当α取8°~14°,b取(1/4~1/2)齿宽B,h取(1/4~1/2)齿高H时,可获得成形质量良好的内齿轮锻件。等效应力分布均匀,无应力集中,且在模具承受范围之内。物理模拟试验得到了齿形饱满、轮廓清晰且无折叠等缺陷的铅制齿轮,与数值模拟结果吻合良好。

To solve the existed problems such as corner filling difficultly and large forming force in the plastic forming process of internal gear,the precision forming process of spur cylindrical internal gear with expansion die cavity was studied based on the existing research on spur gear forming with expansion die cavity.Taking the spur cylindrical internal gear with modulus of 3 mm,tooth number of 18 and external diameter ofΦ80 mm as the research object,the numerical simulation and the physical simulation test of the new forming process were carried out using the finite element software DEFORM-3D and the designed and fabricated experimental mold.The influence of geometric parameters(expansion angleα,dimension b in tooth width direction and dimension h in tooth height direction)on the forming effect of internal gear was discussed.The results show that the forming load of the new process can be reduced by about 70%compared with the closed die forging process,and the upsetting force is raised with the value ofαor(b,h)increases,but the ejection force is reduced,and the corner filling is fuller.When the value ofαor(b,h)is too large,the bottom corner of the internal gear produce wastes.When the values ofα,b and h are selected as 8°-14°,(1/4-1/2)B and(1/4-1/2)H,respectively,the internal gear forging with good forming quality can be obtained.The equivalent stress distribution is uniform without stress concentration and within the bearing range of the mold.The lead gears with full teeth,clear contours and without defects such as folding were obtained by the physical simulation experiment,in good agreement with the numerical simulation results.