铝电解槽阳极导杆电流波动最频值的实用化测量方法

铝电解槽内阳极电流波动的最频值反映了铝液波动的情况。但由于阳极电流的多变性,较难一次性获得最频值。大量实测结果表明,阳极电流波形可分为三类,一类是波动周期比较明显的波形,另一类是没有波动周期的随机波形,第三类是前两类波形的混合波形。周期明显的波形可以方便的获得最频值,而另两类波形能反映一些局部阳极问题。本文通过采用一种LH-80型手持式电流表,方便的获得了这三种类型的曲线信号。并通过采用离散傅里叶变换(DFT)得到的信号最频值,分析了这三种波形信号在判断电解槽稳定性方面的作用。     

135kA预焙电解槽平衡母线的修复技术

介绍平衡母线破损原因 ,及破损导电面修复技术     

铝电解槽磁流体稳定性判据

频率是判据铝电解槽磁流体稳定性的重要参数。每种特定状态下的磁流体都具有一个固有振荡频率（MHD特征频率）。当扰动力频率与该频率值接近或相等时,磁流体的振荡振幅就会无限大增大,这就是共振。共振是不稳定的最危险状态。测量阳极导杆电流波动波形．对该波形进行快速付里叶分析（FFT）,求出最频值。将该值与临界稳定界限相对应的MHD特征频率相比较,是判据槽磁流体稳定性的科学方法。     

广西投资集团330kA电解槽异型阴极焙烧启动实践

主要对焦粒(石墨)焙烧技术在大型预焙电解槽异型阴极上应用进行分析,与国内的其他异型阴极电解槽焙烧启动方法相比,焦粒(石墨)焙烧启动方法更方便、安全、可靠。     

预焙槽阳极电流分布和极距的关系

从理论分析和试验测量两方面研究了在降极距过程中预焙槽阳极电流分布的变化规律。     

铝电解阳极电流分布在线无线监控系统的开发应用

铝电解槽生产中掌握各个阳极电流的分布情况,可以及时了解电解槽的变化趋势,防止偏流的发生,减少电解槽的铝液波动,提高电流效率,保证电解槽的稳定运行。阳极电流分布的在线无线监测,布线短,测量精确,周期短,大幅减少工人巡视测量的劳动强度,为电解槽运行状态提供参考数据,提高了电解槽的管理水平。     

铝、镁合金阳极氧化电流效率测定的研究进展

阳极氧化以及在此基础上发展起来的微弧氧化是改善铝、镁合金表面性能的有效方法,但是能耗高、处理效率低,在工业上的广泛应用受到限制。由于氧化过程中存在金属阳极溶解、已生成氧化膜的化学溶解和氧气析出,使电流效率低于100%。本文综述了测定电流效率的6种方法,同时比较了它们的优缺点。     

自焙阳极电解槽焙烧期间的阴阳极电流分布与测试

对系列自焙阳极电解槽焙烧期间的阴阳极电流分布进行了研究,提出“均流系数”的概念。首次采用便携式直流电流测量仪对焙烧电解槽进行在线电流检测,定量地科学指导焙烧过程两极电流分布的调整与“均流”工作。现场测试中多次发现“负电流”现象,并对此负电流的产生原因与危害作了初步探讨。     

一种簇绒机故障诊断方法的研究

针对簇绒机的故障诊断问题,提出采集滚动轴承的振动信号进行故障诊断.采集的实际振动信号中往往存在噪声信号,需要去掉噪声后再进行诊断.局部均值分解(local mean decomposition,LMD)方法是一种新型的信号自适应分解的时频分析方法,并且已经应用到故障诊断中.为了进一步提高LMD的性能,提出采用分段Hermite插值替代原始的滑动平均方法.提出一种新的故障诊断方法,首先应用小波包变换分析方法,去除信号中夹杂的噪声,然后使用改进后的LMD方法进行信号的分解,选择相关系数较大的PF分量进行希尔伯特变化包络谱分析,成功提取相关的故障特征.通过仿真实例的分析和对滚动轴承的实际故障数据进行故障诊断,证明了该方法在故障诊断应用中的有效性.     

不同槽况下160kA铝电解槽阳极电流的频谱分析

以采集的160kA铝电解槽阳极的电流信号为基础,利用Yule-Walker方法的功率谱估计对其进行分析,提取不同槽况的频谱特征,并将分析结果与HHT(Hilbert-Huang transform)的边际谱分析结果进行对比。结果表明:基于Yule-Walker方法的功率谱估计分析结果能较好地区分正常糟、冷槽及阴极破损槽,并得到正常糟、冷槽及阴极破损槽功率谱曲线主谱峰的频率范围分别为0.003～0.018、0.023～0.027、0.027～0.031Hz;对于不同槽况下的阳极电流信号,HHT的边际谱的主谱峰与Yule-Walker方法的功率谱曲线的主谱峰位置一致,表明功率谱估计分析结果的可靠性。     

大型铝电解槽瞬时电流效率测定技术的研究

主要探讨了采用阳极气体分析法测量大型铝电解槽瞬时电流效率的理论基础,分析了其可能存在的反应过程,并且重新修正了修正系数,通过具体的工业生产数据验证了采用此法测定瞬时电流效率的可行性.     

A practical method to evaluate radiographic unsharpness

A simple method for evaluation of total unsharpness of radiographs using wires of different diameters and plaque type penetrameters instead of knife edge method has been suggested. The theoretical basis of the method and experimental details are explained in this paper.     

一种提升AutoForm分析效率的方法

介绍了提高AutoForm软件分析效率的两种途径,分别是:一、针对每个零件制作各自的设置模板文件,通过引用模板文件,减少操作步骤,可节约分析时间15 min,同时将分析文件的存储空间减小到原来的45％左右;二、针对每个零件建立模面控制线数据库,通过引用控制线数据库,将拉延模面的建立的效率提高了20％,进而提高了整体分析...     

Application of region growing method to evaluate the surface condition of grinding wheels

Grinding is a time-varying process affected by factors such as wheel construction, dressing parameters, operating parameters, workpiece material and cooling. The influence of these factors on wheel wear can be evaluated by monitoring the wheel condition. Measurement of wear flat area provides information on the condition of the wheel, but unfortunately it can be a tedious, time consuming, and expensive process. In this paper, a new system to measure wear flat area is presented. This system is mounted on the grinding machine and automates the measurement process by using computer control to automatically position the wheel and capture digital images of the wheel between grinding cycles. Image processing software is then used to analyze the digital images and measure the wear flat area. The proposed measurement system was validated using a scanning electron microscope. Experiments were performed on a Brown & Sharpe Micromaster 824 surface grinder to examine the relationship between wear flat area, normal force and depth of cut. The results agree with the literature.     

Application of the acoustic resonance method to evaluate the grain size of low carbon steels

The velocities and attenuations of ultrasonic waves in low carbon steels were measured precisely and automatically by the acoustic resonance method using a Lorentz-type EMAT. The attenuations were measured from the decay of a signal from the resonant vibration after stopping the external excitation at the predetermined resonant frequency, while the velocities were calculated directly from the resonant frequencies and material thicknesses. It was not possible to predict the yield strength from the velocity measurements. There was a close relationship between grain size and attenuation in the specimens which consist of ferrite and pearlite. The attenuations measured at a frequency of about 5 MHz showed a good correlation with the average grain size and yield strength. The yield strength could be evaluated within the accuracy of ±50 MPa by the acoustic resonance method. The results would be used for on-line evaluation of the grain size and the mechanical strength of steels in industry.     

电流效率分析仪在电解槽上的应用

介绍了一种电流效率分析仪在400kA铝电解槽上的实测情况。近年来低电压生产是铝电解生产一个热门的技术思路,现在国内最低运行电压已达到3.8V,但是最终的槽电压是多少才能取得最佳的经济指标,还没有一个公认的数据,这与目前缺乏实时、准确的电流效率测试仪器有关。中孚铝业在2009年引进了一台电流效率分析仪,并在400kA铝电解槽上进行了相关测试,各项测试结果表明该仪器的稳定性达到了预想效果。     

铝厂提高电流效率的研究

研究在各项技术条件下 ,如何提高电流效率。通过向电解槽中添加 5 %的氟化镁 ,并且在电解槽上安装盖板 ,这样可控制电解槽温度 ,从而将电解温度降低了 2 0℃。采用以上措施可以节省能量 ,试验的结果也表明电流效率提高了 2 %。     

Advanced use of soft computing and eddy current test to evaluate mechanical integrity of metallic plates

The up-to-date structural designing makes by now widely use of high performance numerical codes, mainly in terms of computational powerful, cost and sizing, only available till some time before to limited groups of users. This allowed the experts to focus their attention on a qualifying aspect of the designing, i.e. an use of the materials very close to their limit behavior. Late innovative approaches in material mechanics gave in addition the opportunity to build models very close to the actual behavior but without introducing heavy computational aspects. In this paper, phenomena which relate mechanical stresses with electromagnetic properties of a defined material have been exploited in order to reconstruct electromagnetic maps starting from mechanical quantities by means of support vector regression machines (SVRMs). Purpose of the proposed study is to reconstruct a stress map in strained metallic plates by using electromagnetic measures. Moreover, an heuristic approach is proposed in order to estimate electromagnetic behavior of a stressed plate starting from easily measurable mechanical quantities. It would be very interesting when electrical or mechanical measurements are very hard to realize. The proposed approach could be very useful in such situations as quality controls of civil buildings, without the necessity of applying expensive and time-consuming destructive or non-destructive testing. In this way, it is possible to have a substantially precise idea of mechanical stresses in metallic materials by estimating the local variation of electromagnetic field into the same material using a SVRM-based interpolator.     

预焙铝电解槽电流效率与阳极电流分布的数学模型

在复杂的综合数学模型的基础上, 利用正交多元回归法研究了预焙电解槽中电流效率与阳极电流分布的关系, 得到一个代数方程式, 同时, 用这个代数方程式分析了阳极电流分布与电流效率的关系.分析结果表明: 阳极电流分布与电流效率都随时间和空间而改变; 阳极电流分布的改变引起电流效率的改变; 在Kuhn Tucker 理论的基础上, 还讨论了系列电流不变时的最佳电流效率, 由于电解槽中磁场、流场分布不均匀等原因, 并非严格均匀的阳极电流分布才能得到最高的电流效率.     

Application of the electrochemical noise method to evaluate the effectiveness of modification of zinc phosphate anticorrosion pigment

A variety of approaches have been proposed to achieve an enhancement regarding inhibitive performance of zinc phosphate (ZP) anticorrosion pigment. This work attempts to study behavior of zinc aluminum polyphosphate (ZAPP) representing modified zinc phosphate pigment through electrochemical techniques along with surface analysis. Analysis of the data obtained from electrochemical noise method revealed superiority of ZAPP compared to ZP. The amplitude of the current noise fluctuation and trend of noise resistance variation as well as shot noise theory suggested precipitation of a protective layer in the presence of ZAPP, restricting access of the aggressive species to the steel surface. X-ray photoelectron spectroscopy (XPS) was employed to analyze the sample surface exposed to 3.5% NaCl solution containing modified pigment extract.