【作者】 张刚；

【导师】 李力钧；

【作者基本信息】 湖南大学 ， 机械制造及其自动化， 2004， 硕士

【摘要】 激光深熔焊接是大功率激光焊接金属材料得以广泛应用的基础。小孔效应是深熔焊接中的特征现象。与此同时，深熔焊接时在工件表面和孔内都存在着高密度的等离子体。等离子体与激光能量的相互作用关系是激光与物质相互作用机理的重要内容之一。 等离子体温度是等离子体物性参数中最重要的一个。其它的物性参数在一定条件下总可以写为等离子体温度的函数。但是一直以来由于试验方法的限制，科技作者主要集中在小孔外等离子体温度的测量上，对小孔内部等离子体的温度研究较少。本文利用新的试验方法和自制试验装置首次试验研究了激光深熔焊接孔内等离子体的温度情况。论文工作主要有以下几个方面： 首先确定试验方案。经过考察研究并借鉴国内外研究成果的基础上，确定采用模拟焊接试验来研究孔内等离子体温度。论文吸取“三明治”的思想，在两块透明的玻璃之间夹持一定厚度的铝膜，来模拟研究实际的铝及其铝合金焊接中的等离子体。经过分析考察，选择具有优良性能的GG17作为试验用夹持材料；采用0.2mm和0.02mm厚度的铝膜作为焊接材料。试验为了不干扰等离子体的物理场，本文采用光谱分析间接测量温度法。同时经过大量的试验，选择二价的铝谱线作为计算用的谱线。 其次自行设计开发了实用的光学多道分析系统，并在硬件的基础上开发了相应的软件。光学多道分析仪是光谱测量的一个主要工具。目前的许多产品类型已经比较的多，但是大多只能对稳定光源进行测量，对于动态过程则反映较慢。论文前期的工作主要集中于试验用光谱分析仪的设计研究上。在现有试验条件基础上设计的棱镜光谱分析系统理论分辨率分布达到纳米数量级，基本满足了试验的要求。 最后，利用光谱分析法中的相对光强法研究了不锈钢工件表面等离子体的温度与工艺参数之间的关系。试验测定不锈钢工件表面等离子体温度在7000K到8000K之间。同时论文主要研究了深熔焊接中孔内等离子体温度以及不同工艺条件下等离子体温度。论文首次利用光谱分析法测量到孔内等离子体的光谱，并计算得到在文中所选工艺条件下等离子体的温度在20000K以上。另外论文研究了不同工艺条件与等离子体温度、焊接熔深和焊缝宽度的定性关系。 另外论文中利用高速数码相机拍摄了激光深熔焊接小孔以及等离子体的动态变化过程，分析讨论了小孔振荡与等离子体密度变化的关系。利用自制装置结合几何光学的知识，试验估算了等离子体的空间尺度。其空间轴向尺度在1～3mm激光深熔焊接光致等离子体温度测量的试验研究之间。更多还原

【Abstract】 The deep penetration Laser welding is the base of extensive utilization for the high-laser welding of metal materials. And the keyhole is characteristics of deep penetration laser welding. The plasma of the high density always exists above work piece and in the keyhole, so that the interaction relation between plasma and laser energy is one of important studies of the laser and material interaction mechanism.The plasma temperature is the most important one in plasma parameters while others can always be described by the function of plasma temperature under certain condition. Then the author launches the research about simulated experimentation result for the plasma temperature. The former workers mainly concentrated on the measurement of density and temperature of plasma outside the keyhole because of the limits of experimentation methods, but thought less about the parameter of the plasma inside the keyhole. A new experimental method and the instrument made by oneself is utilized to investigate the temperature inside the keyhole in this thesis for the first time. So this is decided the studies.Firstly, designing the experimentation scheme. It is determined to adopt simulation experimentation to study the plasma temperature inside the keyhole on the base of studying the achievement at home and abroad. The author draws the thought of sandwich", that is grasping the aluminum film of certain thickness between two pieces of transparent glasses. GG 17 Glass was used to grasp aluminum film that is only 0.2 mm. For the sake of not interfering with the plasma physics field, the relative spectral analysis was used to calculate the temperature. The spectral line of A1II was chosen.Secondly, Optical Multi-channel Analyzer system is designed and developed by oneself and the corresponding software is programmed on the basis of hardware. Then Opticak Multi-channel Analyzer is a kind of main tool for the temperature measurement. A lot of present products have already been presented, but most of them can only do measurement for the stable light sources. The responding time to the dynamic motion is relatively slow. In earlier stage of the thesis, the author concentrate on Optical Multi-channel Analyzer design for experimental request mainly. This optical instrument is so accurate that its resolution ration comes to nm level. So, it is satisfied with the experimentation request basically.At last, it is well studied that the relation between the technical parameters and temperature by the relative spectrum method .The plasma temperature over the stainless steel work piece is from 7000K to 8000K.At the same times, the relation of the plasma temperature and the technical parameter is also investigated .The plasma spectrum of aluminum work piece inside the keyhole is observed firstly and the temperature is computed. The results show that the plasma temperature is over 20000K under the specified conditions of the thesis. In addition that the relation in different process conditions and quality of weld such as weld breadth and weld depth is also analyzed.The author utilizes the digital camera of high speed to shot the dynamic course of the deep penetration weld, and analyzed the links between plasma density and the keyhole dynamics. Additionally malting use of the knowledge optics and the spectral device to measure the scale of the plasma .The experimental result shows that the plasma scale is 1-3mm.更多还原