【作者】 徐文豪；

【导师】 杨立军；

【作者基本信息】 天津大学 ， 材料加工工程， 2012， 硕士

【摘要】 激光焊接作为新型焊接技术,以其能量密度高、焊接热输入小、焊速高等优点日益受到重视。在激光焊接过程中,随着激光能量的增大,会产生激光焊接等离子体,它对焊接过程有着重要影响,甚至能够决定焊接的成功与否。因此,对激光焊接等离子体的检测研究具有重要意义;研究等离子体性质和内部作用机制,有助于深入理解激光焊接作用机理,改进激光焊接工艺。等离子体的诊断与检测主要有声、光、电及光谱方面的方法,其中光谱和高速摄像等宏观研究方法使用较多,而电信号应用较少。国内外研究多采用单一检测方法,各信息结果孤立;而激光焊接等离子体波动变化剧烈,这就需要在较高时间分辨率下进行研究;对实时条件下激光等离子体波动现象的光谱诊断研究也尚不多见。为此,本文自主设计了光谱信号、电信号以及高速摄像同步采集系统,对相同时刻下的激光焊接等离子体进行多维信息采集。通过分析等离子体特征参数以及波动特征,来研究激光焊接等离子体的能量与物质传输规律。对激光焊接等离子体采集到的同步信号进行分析后,可以得出:光电采集系统能够全面获取等离子体特征信息,各信号参数特征明显,其变化规律与等离子体波动规律一致,可以全面表征等离子体特征及变化规律。采用方波脉冲激光进行焊接实验,发现等离子体波动现象有两种表现形式。采集到的多维信号能够解释等离子体的波动性现象,且符合相关理论。对采用活性剂的激光焊接研究后发现,复合信号特征能很好的对应活性剂作用机理。本文设计的多信息复合采集系统,可以对激光焊接等离子体进行多维信息分析,具有很好的实用性,为研究激光焊接本质提供了有效的方法。更多还原

【Abstract】 Laser welding, as a new welding technology, is becoming highly valued. Laser welding has many advantages such as high energy density, small heat affected zone, high welding speed. In the welding process, plasma will be generated with more laser energy. It has an important impact on the welding process and even determines the success of welding. Therefore, the study of laser welding plasma is of great significance. The research of plasma properties and internal mechanism contributed to a better understanding of the mechanism of laser welding and the improvement of laser welding process.The plasma diagnostics involve many methods, such as sound, light, electricity and spectral method. The spectral method and high-speed photograph are widely used, while the method of electric signal is seldom used. The domestic and international researches always adopt single detection method, research results are isolated. It requires a higher time resolution study that the laser welding plasma changes dramatically. There are few spectral investigations about wave phenomena of laser welding in real time.Therefore, this thesis firstly designs a new data synchronous acquisition about spectrum signal, electric signal and high-speed photograph. This acquisition could collect multi-dimensional information of laser welding plasma at the same time. The paper studies propagation law of matter and energy in laser welding plasma, through analyzing the characteristics of the parameters and wave characteristics of plasma.Results obtained from the study of multi-dimensional information are as follows: The optical and electrical synchronous acquisition system is able to obtain the whole feature information of plasma. The features of signals are characteristic and their changing rule is accorded with the variation law of plasma. The hybrid signals could fully characterize the variation of plasma.In the experiment of squarewave pulse laser, two forms of wave phenomenon are found. Multi-dimensional signals can explain the volatility of plasma, and are in accordance with relevant theory. In the laser welding with activating flux, the features of hybrid signals correspond with the mechanism of activating flux. The optical and electrical synchronous acquisition system could analysis the multi-dimensional information of laser welding plasma. It is practical with satisfactory results and provides a new way to research the laser welding deeply.更多还原