【作者】 万淑敏；

【导师】 胡仕新；

【作者基本信息】 天津大学 ， 机械制造及其自动化， 2007， 博士

【摘要】 半空心铆钉自冲铆接技术成功地解决了汽车轻量化带来的车身连接的问题,是近几年才发展起来的适用于铝合金等轻金属的连接以及不同金属材料之间连接的新工艺,对该技术的研究从理论和实验方面都不够系统和深入。本文以半空心铆钉自冲铆接技术为研究对象,运用实验和数值模拟相结合的方法,对6063铝合金板材自冲铆接的工艺过程和铆接接头的力学性能做了全面的研究。本论文的主要工作如下:1.提出了半空心铆钉自冲铆接工艺参数的设计原则,研究了主要工艺参数的设计方法。给出了铆钉腿部直径和铆钉长度的选择依据、理论计算公式和尺寸圆整原则;探讨了模具模腔尺寸的设计,给出了模具深度、模具直径、凸台高度等计算方法,确定了板材厚度、模具和铆钉的合理匹配关系。2.应用自行设计的自冲铆接实验系统,对自冲铆接工艺过程进行了研究。采用分步实验和有限元模拟对铆接过程中的铆扣的形态进行了分析,结合载荷位移曲线,得到了压紧、对上层板料的穿透、铆钉尾部张开和墩锻四个阶段的铆钉和板料变形规律和应力分布,验证了有限元分析的准确性。3.提出了表观质量的评价标准,应用截面测量法的相关参数评价了不同工艺参数下的铆接质量。运用有限元方法和实验方法,全面分析了模具几何参数、铆钉几何参数和硬度以及板料厚度对铆接过程中铆接力和铆接接头表观质量的影响。为优化自冲铆接的工艺参数提供了理论依据。4.针对搭接和T形连接的自冲铆接试件,分别进行了拉伸实验和计算机模拟,探讨了模具凸台高度、铆钉硬度和板料厚度对铆接接头静力学性能的影响。模具凸台高度对拉伸力学性能的影响与板料厚度有关,存在一个最佳的匹配关系,使得自冲铆接接头获得最佳的拉伸性能,拉伸载荷随板料厚度的增加而显著增加。5.通过对比分析自冲铆接接头的峰值强度极限和板料强度极限,提出了当量宽度的概念,并给出了其计算方法。当量宽度可以作为构件铆接点间距设计的参考依据。6.比较研究了自冲铆接接头与电阻点焊接头的力学性能。通过研究载荷位移关系和拉伸试件的峰值载荷,自冲铆接头拉伸峰值载荷大于电阻点焊接头,疲劳性能优于点焊,自冲铆接接头破坏的变形能大于电阻电焊接头。由此可以推断,自冲铆接头的综合机械性能优于电阻点焊接头。更多还原

【Abstract】 Technology of self-piercing riveting (SPR) with half-hollow rivets has been successfully applied to joining difficult-to-weld as well as dissimilar materials for lightweight automobile body construction. However, systematic theoretical and experimental investigations of SPR have been lacking. In this thesis, the technology of SPR with half-hollow rivets is investigated thoroughly using experiments and numerical simulations with 6063 aluminum alloy sheet. The mechanical properties of riveted joints of are studied. The main contributions of this dissertation are as follow:1. A set of design principles for SPR with half-hollow rivets are proposed based upon thorough investigation of the SPR process. Methods for rivet size selection and die geometry parameters calculation are given. Relationships between rivet size, die cavity, pip height and sheet thickness are also established.2. The mechanics of SPR process is investigated using the SPR system designed by the candidate and her faculty team. Experiments and numerical simulation are used to obtain a punch load vs. punch displacement curve, which relates to the four phases of rivet piercing, insertion and deformation process.3. A set of criteria for visual inspection of SPR joint quality are proposed. Experimental method is used to study the effect of die geometric variables, rivet geometric variables, rivet hardness and sheet thickness on the riveting load and riveted joint apparent quality in the riveting process. Using finite element method, the effect of the geometric parameters of die, rivet and sheet on riveting process is analyzed comprehensively.4. Computation and experiments are carried out to study the static load performance characteristics of SPR lap joints and T-joints. The effect of die geometry, rivet hardness and material thickness on tensile strength is analyzed. It was discovered that the die pip height and sheet thickness have a strong influence on the tensile behavior.5. The concept of“Equivalent Width”and its calculation method are proposed by comparing the strength of a sheet sample with the strength of a SPR joint.“Equivalent Width”provides guidance in designing the pitch in multi-riveted structures.6. The performance of SPR joints is compared with the resistance spot welded (RSW) joints of the same sheet material. It is shown that SPR joints have superior static and fatigue performance. The displacement to failure in SPR joints is also higher than RSW joints. Therefore, SPR joints can absorb more energy than RSW joints.更多还原