铆压重塑形工艺的铆钉优化与试验研究

Rivet Optimization and Experimental Research on the Reshaping Method

为解决传统机械变形压力连接存在较高凸起的问题并增加连接强度,提出了一种采用特制铆钉的铆压重塑形工艺。该工艺在无铆连接工艺后将铆钉置于连接点的凹坑内,然后压缩凸起处使凸起高度降低。采用DEFORM-2D软件对铆压重塑形工艺进行有限元分析,得到了连接点的最大拉伸强度;采用正交试验方法对铆钉尺寸进行了设计优化,得到了能实现最大拉伸强度的铆钉尺寸。在铆压重塑形试验中,连接点的凸起高度从1.6 mm降低到了1.1 mm;平均拉伸强度从950.6N提高到1 130.7N,即重塑形后的拉伸强度比重塑形前提高了18.9%;平均剪切强度从1 168.6N提高到2 636.1N,即重塑形后的剪切强度比重塑形前提高了125.6%。由此证明,铆压重塑形工艺可有效降低凸起高度,并且能提高连接点的强度。

The application of conventional mechanical clinching in automotive industry is restricted because of the exterior protrusion. In order to reduce the protrusion height and increase the strength of clinched joint, a new rivet-reshaping process was proposed to reshape the clinched joint in this study. The rivet was embedded in the pit of the joint after the conventional mechanical clinching and then the protrusion was compressed to reduce the protrusion height. The maximum tensile strength of the clinched joint was obtained by finite element simulation using the software DEFORM-2D. The geometrical parameters of the reshaped rivet with maximum tensile strength were acquired by optimization using orthogonal design. In the experiment, the protrusion height of the reshaped joints was reduced from 1.6 to 1.1 mm. The average tensile strength of the reshaped joints was increased from 950.6 to 1 130.7 N, i.e. the average tensile strength was increased by 18.9% compared with the clinched joints before reshaping; and the average shear strength of the reshaped joints was increased from 1 168.6 to 2 636.1 N, i.e. the average shear strength was increased by 125.6% compared with the clinched joint before reshaping. It was proved that the reshaping method can reduce the protrusion height and increase the strength of clinched joint effectively.