高分子材料ABS与金属电阻焊连接工艺及机理的研究

发布时间：2018-06-05 10:58

本文选题：轻量化 + 电阻焊　；参考：《兰州理工大学》2017年硕士论文

【摘要】：近年来随着石化资源的日渐枯竭和人们居住环境的进一步恶化,在现在工业生产中,轻量化制造逐渐成为一种实现节能环保的有效途径,尤其在汽车工业和航天航空工业中铝、镁、钛和其合金等轻金属材料和塑料、碳纤维和复合材料等非金属材料应用的增加大大促进了轻量化生产的进程,因此金属与非金属的连接在轻量化生产中占有重要地位。本文开展热塑性高分子塑料与金属电阻焊研究,优化工艺后获得综合性能优异的连接接头,为工业轻量化进展提供了技术支持。采用ABS塑料、纯铝和Q235钢板为试验材料,以自主设计的多电极多功能焊机为试验平台,制定全新工艺方案,通过次级回路和三个电极的组合,实现金属板上单边通电,金属产生的电阻热作为焊接热源传递到ABS塑料板,塑料在温度和压力作用下熔化铺展与金属形成有效连接,并对接头成型、力学性能和连接机理开展如下研究:基于Lab VIEW数据采集系统,实现焊接过程中电信号的采集,对比分析焊接过程中材料的变形行为,研究焊接参数改变对焊接质量的影响,进行工艺优化。焊接电流或时间增大时,接头有效连接面积增大,接头强度提高且同一参数结果离散性减小,但热输入过大导致界面熔化的塑料被大量挤出,接头存在很大应力集中,接头性能变差;电极压力改变时,接头强度未出现稳定的变化趋势,且试验结果存在较大离散性。通过开展接头力学性能测试,得出接头拉伸失效有三种形式:搭接界面拉开、界面塑料撕裂和塑料母材断裂,界面拉开失效载荷较小,拉伸曲线在线性变化阶段达到峰值并失效;界面塑料撕裂和塑料母材断裂时,接头强度达到甚至超过母材强度,拉伸曲线在线性变化之后出现明显的屈服阶段,母材断裂的屈服阶段持续较长,这种接头强度最高。为改善焊接质量,采用超声波辅助施加到焊接过程中,通过与常规工艺对比分析,研究超声辅助前后接头成型与力学性能,相同参数下施加超声辅助后,超声辅助能明显改善接头质量,接头有效连接面积增大,强度提高约10%且结果离散性减小。通过接头横截面和界面塑料撕裂微观形貌的观察、界面元素能谱分析、红外光谱分析及X射线光电子能谱分析等,研究ABS塑料与金属的连接机理,得到二者连接为机械互锁、扩散和配位键多种机制共同作用。
[Abstract]:In recent years, with the depletion of petrochemical resources and the further deterioration of people's living environment, lightweight manufacturing has gradually become an effective way to realize energy saving and environmental protection in industrial production, especially aluminum in automobile industry and aerospace industry. The increase of applications of light metal materials such as magnesium, titanium and its alloys and plastics, carbon fiber and composite materials has greatly promoted the process of lightweight production. Therefore, the connection between metals and non-metals plays an important role in lightweight production. In this paper, the resistance welding of thermoplastic and metal was studied. After optimizing the technology, the joints with excellent comprehensive properties were obtained, which provided the technical support for the development of industrial lightweight. Using ABS plastics, pure aluminum and Q235 steel plate as test materials, taking the self-designed multielectrode multifunctional welding machine as the test platform, a new process scheme was established. The single side electric current on the metal plate was realized through the combination of the secondary circuit and the three electrodes. The resistance heat generated by the metal is transmitted to the ABS plastic sheet as the welding heat source. The plastic is melted and spread under temperature and pressure to form an effective connection with the metal, and the joint is formed. The mechanical properties and joining mechanism are studied as follows: based on LabVIEW data acquisition system, the electrical signals are collected during welding process, the deformation behavior of materials in welding process is compared and analyzed, and the influence of welding parameters on welding quality is studied. Process optimization is carried out. When the welding current or time increases, the effective connection area increases, the strength of the joint increases and the dispersion of the same parameter decreases, but the plastic melted at the interface is extruded by excessive heat input, and there is a great stress concentration in the joint. When the electrode pressure is changed, the strength of the joint does not change steadily, and the test results are discrete. Through testing the mechanical properties of the joints, it is concluded that there are three forms of tensile failure of the joints: the lap interface pulling, the interface plastic tearing and the plastic base material breaking, and the interface pulling failure load is small. When the interfacial plastic tear and the plastic base material break, the strength of the joint reaches or even exceeds the strength of the base metal, and the tensile curve appears obvious yield stage after the linear change. The yield stage of base metal fracture is long and the strength of this joint is the highest. In order to improve the welding quality, ultrasonic assisted welding was applied to the welding process. By comparing and analyzing with the conventional technology, the molding and mechanical properties of the ultrasonic assisted front and rear joints were studied, and the ultrasonic assisted joint was applied under the same parameters. The ultrasonic assistant can obviously improve the quality of the joint, increase the effective connection area, increase the strength by about 10% and decrease the dispersion of the results. The bonding mechanism of ABS plastics and metals was studied by observing the micromorphology of the joint cross section and interfacial plastic tearing, analyzing the interface element energy spectrum, infrared spectroscopy and X-ray photoelectron spectroscopy, and obtained that the connection between ABS plastics and metals was mechanical interlocking. Multiple mechanisms of diffusion and coordination bond work together.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG453.9

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