Eigenvalue extraction of current signal during spot welding based on space-phase reconstruction

Nonlinear methods are used to analyze current signal of spot welding and the minimum embedding dimension, correlation dimension, the optimal time delay and the largest Lyapunov exponent of current signal time series are calculated in this paper. The chaotic character of current signal time series is discovered. Then a chaotic neural network is built and used to predict the future current signal. Means of residual error out of the network are used us eigenvalue of current signal during spot welding. It is shown that spatter can greatly affect the means of residual error of spot welding after analysis, the mean values of output errors of signal contaminated by spatter noise are more than O.08,but the mean values of output errors of the signal with no spatter noise are less than O.04,so mean of residual errors can be employed as the character of spatter.     

焊接远程监测技术在现场中的应用

焊接远程监测技术是Internet、Intranet、计算机及其相关技术与焊接技术相结合的新一代远程监测系统,它使分散在异地的焊接专家们能及时指导、解决现场问题。本文较为详细地讨论了焊接远程监测技术的系统性能、应用发展状况及现阶段存在的有关问题。     

双电源智能型IC卡水表的研制

简单介绍了IC卡水表的测控电路组成及程序设计框图,并分析了自行设计的“采样&供电模块”的工作原理及采用双电源的必要性。首次提出了对IC卡水表的阀门进行模糊控制的思想及控制方案,使IC卡水表具有了真正意义上的智能特性。实践证明,该模糊控制方案可有效地解决IC卡水表使用寿命的“阀门瓶颈”问题。     

水下航行体专用线缆的开发与发展

对水下航行体专用线缆(电线电缆和光纤)的开发进行了较全面的阐述，着重论述其特点，并对其发展作了展望。     

等离子弧堆焊TiB2-金属陶瓷涂层的组织及性能

采用等离子弧堆焊设备，通过钛合金和硼合金粉末之间的高温冶金反应，在堆焊过程中原位合成了TiB2，在普通碳钢表面制备了含TiB2的金属陶瓷层。并对堆焊层进行了显微组织、X射线衍射分析、硬度及抗裂性能试验。试验结果表明，这种一步性原位合成工艺所获得的堆焊层主要由针状TiB2晶须与Fe及其硼、碳化合物组成，陶瓷层与基体间实现了冶金结合；堆焊层抗裂性能优于不含TiB2的铁基B4C堆焊层。     

用时频分析法研究铝合金电阻点焊过程中的声音信号

研究了铝合金点焊过程中声音信号的时频域能量分布，并应用它来识别点焊的熔核状态。点焊过程中的声音信号包含着熔核形成信息，是点焊质量监控的重要参数。为了能够确定熔核的变化状态，作者尝试采用非平稳过程的时频分析方法对声音信号进行研究，试验与计算结果表明，Choi-williams时频分布是一种较好的铝合金点焊声音分析方法，可以区分不同熔核状态，其计算结果可作为铝合金点焊过程的监控参数和质量检验的依据，具有一定的实用价值，同时它对其它焊接方法中的信号分析与处理也有较高的参考价值。     

建筑物内低压系统雷击及过电压保护

综述建筑物内低压系统中产生过电压的主要干扰源及其干扰途径,并介绍雷电过电压防护级别的确定、保护器的特点和选择。     

利用虚拟仪器技术研究铝合金点焊过程质量参数

利用虚拟仪器软件开发工具LabVIEW设计了铝合金点焊质量检测系统,该系统可实现点焊过程中各特征信号的采集、显示、存储和数据分析等动能。试验证明,检测系统能够满足铝合金点焊过程中实时质量监测的要求。     

The Asymmetric Laplace Law for distribution of aluminum contact resistance in spot welding

This paper investigates the distribution of contact resistance of the aluminum alloy in the squeeze stage. A new method of measuring path＇ s resistance is proposed firstly. Contact resistances are calculated accurately by the systems of 5 linear equations and solutions show that three contact resistances are different. The probability density functions of contact resistance in workpiece/workpiece（ W/W） and upper electrode/workpiece（ E/W） show that the curve shape has steeper peak and heavier tail than that of the normal distribution. Non-parameter hypothesis test is performed and the result shows that R2 , R4 reject the normal distribution using chi-square and kolmogoroo statistic D method. Therefore, the Asymmetric Laplace distribution is fitted to empirical distributions and is applied to quantify the influence of random contact resistance. The result illustrates that AL distribution is very close to contact resistance of W/W and upper E/W and normal distribution has some deviation. The paper is helpful to research the initial nugget conditions, weldability and the transient multi-coupling field.     

穿孔等离子弧焊接中等离子云的检测

应用天体物理等离子鞘层理论的知识，分析金属板测量尾馅时产生电压和探针测量等离子云时产生电压的原因。当把探针放置在等离子云中，由于等离子体的特殊性，将在探针上产生了负电位，与工件电位差就是鞘层电压，并给出鞘层电压的计算公式，通过分析发现，鞘层电压大小仅仅与检测处等离子体温度和成分有关。提出了一种用无电源探针检测等离子云的新方法，通过检测等离子云中探针上产生的鞘层电压是否为零来判断小孔是否形成。试验验证了鞘层理论在等离子弧焊接中应用的正确性，同时给出了探针放置的最佳位置。