车身点焊、抽芯铆接及胶铆接头的拉剪强度对比分析

Comparative Analysis on Tensile-shear Strength among Spot Welded,Blind Riveted and Bond Riveted Joints on Auto Body

在车型开发前期的样车试制或小批量生产验证过程中,人工操作比例高,焊点缺陷难以完全避免,进行焊点修复时就需要根据缺陷位置的实际情况选择合适的焊点替代方案。选取车身材料中具有代表性的双相钢CR440Y780T-DP与低合金高强钢CR340LA为基材,对比分析了电阻点焊接头、多鼓型抽芯铆接接头、结构型抽芯铆接接头、多鼓型及结构型抽芯铆钉分别与环氧树脂基结构胶Betamate 1630、聚氨酯结构胶Teroson PU6700组合接头的拉剪强度。试验结果表明:(1)结构型抽芯铆钉与胶Betamate 1630的组合与原点焊接头抗剪能力最接近,可达到约80%的连接强度;(2)结构型铆钉与多鼓型铆钉相比,抗拉剪强度提升约15%,但钉头高度较高,需要更大的操作空间;(3)Betamate 1630对铆接接头的静态连接强度提升效果明显(与多鼓型抽芯铆钉组合时,抗剪强度比单独铆接接头相比提升约5%~10%;与结构型抽芯铆钉组合时,强度提升约20%~30%);(4)Teroson PU6700在接头强度方面作用不明显,无论与多鼓型铆钉或结构型铆钉组合,接头最大失效载荷和失效形式均没有明显变化,实际应用中以密封为主要目的。通过以上试验,对比总结了常用焊点替代方案对局部结构连接强度的影响程度,为实际生产中快速确定车身焊点修复方案提供了试验与理论依据。

In the prototype trail-manufacture or small batch production phase of vehicle development,the weld spot defect is usually difficult to avoid completely due to the high proportion of manual operation.It is necessary to choose a suitable alternative solution to the defect weld spot according to the actual situation of the location for defect weld spot repair.Selecting the representative dual-phase steel CR440Y780T-DP and low-alloy high-strength steel CR340LA as the base materials in the body material,the tensile shear strengths of resistance spot welded joints,multi-drum blind riveted joints,structural blind riveted joints,multi-drum and structural blind riveted joints bonded with epoxy resin-based structural adhesive Betamate 1630 and polyurethane structural adhesive Teroson PU6700 respectively are comparatively analysed.The test result shows that(1)the combination of structural blind rivets and adhesive Betamate 1630 has the closest shear resistance to that of the origin welded joint,which can reach about 80%of the connection strength;(2)compared with multi-drum rivets,structural rivets have an increased tensile-shear strength of about 15%,but it also needs more operation space due to its head length;(3)the adhesive Betamate 1630 can obviously improve the static connecting strength of the riveted joints(the shear strength is increased by about 5%-10%compared with a single riveted joint when combined with multi-drum blind rivets,and the strength is increased by about 20%-30%when combined with structural blind rivets);(4)the adhesive Teroson PU6700 shows limited effect in terms of the joint strength with either multi-drum rivets or structural rivets,there is no obvious change in the maximum failure load and the failure mode of the joints,and to seal the joints is therefore the main purpose of applying this kind of adhesive in real practice.Through the test,the influences of common welding spot alternative on the connection strength of local structure are compared and summarized,which provides an experimental and theoretical basis for quickly determining the repair scheme of welding spots on auto body in actual production.