直齿圆柱齿轮冷精锻成形过程数值模拟分析

对直齿圆柱齿轮冷精锻成形过程进行了三维大变形弹塑性有限元数值模拟。对闭式模锻预锻及以闭式模锻、孔分流及约束分流为终锻的两步成形过程的流动情况进行了数值分析。数值模拟结果及前期的工艺试验表明：终锻中采取分流、尤其是约束孔分流措施对于降低工作载荷、提高角隅充填能力十分有利，采用矩阵变换技术解决因引入边界摩擦及滑动约束带来的刚度阵非对称问题较为简单、合理、有效。

A Numerical Simulation of Cold Precision Forging Process for Spur Gears

A working load is remarkably increased and material filling into the die cavity is extremly difficult during a cold precision forging process of a spur gear. In such a process, the plastic flow of material is quite complex and the product quality is very difficult to control. So, the prediction of the deformation behaviors, the determination of technological specifications and the design of a die have to be followed by a study of numerical simulation. In this paper, a 3D large deformation and elasto plastic FEM was adopted to numerically simulate a cold precision forging process of a spur gear. With the FEM, a numerical analysis of the flow pattern in a two step forging process was performed. The two step forging process consists of a closed die forging as the pre forging stage and divided flow forging or divided flow forging as the final stage. The results of the numerical simulation and the technological experiments showed that the divided flow, especially the constrained hole divided flow applied in the final forging stage was very effective on decreasing the forging load and improving the corner filling. A scheme of matrix transformation can maintain symmetric stiffness matrices, which increases the solving efficiency of the equations and is reasonable and valid when a slipping constraint and friction boundary condition is introduced into a 3D problem.