锻压技术

活塞销冲孔局部变形分析及改进

英文标题：Analysis and improvement on local deformation of punching for piston pin

作者：袁磊冉均均

分类号：TG316.1+5

出版年,卷(期):页码：2022,47(7):13-19

摘要：

以某款内燃机活塞销为研究对象，分析其冲孔成形底部出现较大局部镦粗变形的原因并进行修正。首先，对活塞销用材料20CrH钢试样进行室温下的拉伸和压缩试验，利用DEFORM软件对拉伸过程进行数值模拟，以韧性断裂准则Normalized Cockcroft & Latham（NCL）为模型求解出其临界破坏值为0.22。其次，应用NCL模型对活塞销冲孔成形过程进行数值模拟，分析其冲孔局部镦粗变形的原因为：筒壁外侧为无径向约束状态，冲孔过程中，在与连皮对应相连接的筒壁处出现轴向与径向的复合金属流动。最后，在不改变原有模具的基础上，提出一种通过减薄连皮厚度来减弱底部局部镦粗变形的解决方法，数值模拟与工艺试验结果表明，该方法可以保证冲孔后活塞销外圆柱面的尺寸不会因为局部镦粗变形过大而超差。

For a piston pin of an internal combustion engine, the result of excessive local upsetting deformation at the bottom of piston pin punching was analyzed and corrected. Firstly, 20CrH steel samples for piston pin materials were subjected to tensile and compression tests at room temperature, the tensile process was numerically simulated by software DEFORM, and the Normalized Cockcroft & Latham (NCL) ductile fracture criterion was used as a model to solve the critical value of 0.22. Secondly, the NCL model was used to numerically simulate the punching process for piston pin, and the reasons for the local upsetting deformation of piston pin punching were analyzed. The outside of the cylinder wall was in state of no radial constraint, during the punching process, the axial and radial composite metal flow occurred at the cylinder wall corresponding to the connecting skin. Finally, on the basis of not changing the original mold, a solution method was proposed to reduce the local upsetting deformation at the bottom by reducing the thickness of connecting skin. The results of numerical simulation and process test show that this method can ensure that the size of the outer cylindrical surface of piston pin after punching will not be out of tolerance due to excessive local upsetting deformation.

基金项目：

乐山市科技局重点研究项目（21GZD029）

作者简介：袁磊（1986-），男，硕士，讲师 E-mail：yuanlei11@163.com

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