振动监测技术在连轧机组齿轮箱状态管理中的应用与实践

轧机齿轮箱作为连轧机组的关键设备,对其运行状态的受控管理至关重要,但是仅依靠人工手动检测及个人经验判断,很难准确判断各零部件的实际运行情况及劣化趋势,更无法做到提前状态预知与及时更换。为了有效解决这一实际问题,通过安装在线振动监测系统,可对齿轮箱各零件的运转情况实现24 h连续监测,并通过数据对比分析,能提前掌握各零件的劣化趋势,也能在恰当的时间储备一定数量的备件,并有针对性的更换已出现劣化的零件,避免发生恶性设备事故。     

XRD Analysis of Local Strain Fields in Pearlitic Steels ‐ towards the Fast Examination of Microstructure after Hot Rolling

Analysis of the crystallographic anisotropy of the lattice strains, i.e. the analysis of the dependence of the lattice strain on the crystallographic direction, is discussed to be an efficient method for getting information about the mesoscopic local strains and microscopic local strain fields in dual‐phase materials. This technique is illustrated on the example of hot‐rolled pearlitic steels containing ferritic lamellae separated by cementite from each other. In these samples, the information about the local strain fields was further used to build a microstructure model that describes the interaction between crystallites of different phases on the microscopic scale. Such a microstructure model is quite appropriate for examination of the correlations between the structure and properties of the pearlitic steels, because it links the microstructure parameters obtained using X‐ray diffraction on the atomic level with the interaction between the crystallites or grains of different phases, which can more directly be related to the macroscopic mechanical properties of the materials. The second important result of this study was the detection and explanation of several correlations between individual microstructure parameters, which are obtained from X‐ray diffraction. This offers a possibility to use the X‐ray diffraction for a fast microstructure analysis of pearlitic steels, or generally for a fast microstructure analysis of dual‐phase steels, after or even during the rolling processes.     

Process Modeling for Precision Forming of Discrete Parts – State of the Technology and Critical Issues

This paper presents an overview on the application of FE simulation as a virtual manufacturing tool in designing manufacturing processes for precision parts. The processes discussed include forging, sheet metal forming and hydroforming. Determination of reliable input parameters to simulate a process is a key element in successful application of process simulation for process design in all the mentioned areas. These issues are discussed in detail. Practical examples of application of FE simulation are presented for improvement of the existing metal forming process and/or designing new metal forming process for manufacturing discrete precision parts in forging, sheet metal forming and hydroforming.     

Effect of FeO and Al2O3 on the MgO Solubility in CaO–SiO2–FeO–Al2O3–MgO Slag System at 1823 K

The MgO solubility in CaO–SiO₂–FeO–Al₂O₃–MgO quinary slag system at 1823 K was measured to evaluate the effect of FeO and Al₂O₃ on the MgO solubility. It was found that the MgO solubility was decreased with higher optical basicity, FeO concentration, and increased with higher Al₂O₃ concentration. The MgO solubility was affected by activity coefficient of Mg²⁺ ($\gamma _{{\rm Mg}_{{\rm 2 + }} } $ ). Increase of the activity coefficient of Mg²⁺ ($\gamma _{{\rm Mg}_{{\rm 2 + }} } $ ) with higher FeO or lower Al₂O₃ decreased the MgO solubility. The increment in MgO solubility is remarkably reduced beyond a critical $X_{{\rm Al}_{2} {\rm O}_{{\rm 3}} } /(X_{{\rm Al}_{2} {\rm O}_{{\rm 3}} } + X_{{\rm FeO}} )$ ratio. The significant decrease of the increment of MgO solubility is caused by the change of the molten slag structure. The excess stability function of Al₂O₃ and the Fourier transform infrared (FT‐IR) analysis were applied to indirectly verify the existence of the spinel structure in the CaO–SiO₂–FeO–Al₂O₃–MgO slag system.     

Physical properties in the temperature range from –180 to 400°C of nickel alloy steels for low-temperature applications

Nickel, which is the second neighbour to iron in the periodic table of elements, has a significant effect on most of the physical properties of the steels studied here, with the nickel content of the steels varying between 3 and 9%. Density and coercive force increase as the nickel content in the steel increases. By contrast, thermal expansion, modulus of elasticity and shear modulus decrease with increasing nickel content. Because of large scatter in the data, it is not possible to notice any significant influence of nickel content on Poisson's ratio and bulk modulus. Specific heat is also found not to vary with the nickel content of the steel. Electrical resistivity and thermal resistivity values increase, as expected, with increasing nickel content. The results of thermal conductivity measurements on 12 Ni 19 and X 8 Ni 9 have led to the development of modified Smith-Palmer relationships, which allow the calculation of the thermal conductivity values for the present set of steels and other steels with similar compositions.     

Laboratory studies on smelting reduction – a contribution to reaction mechanisms in the production of liquid iron from iron oxide melts

Iron oxide slags are subjected to reduction at 1550 °C with the use of various reducing agents. The experiments with carbon monoxide are subdivided into series of top-blowing, injection or bottom-blowing experiments. Moreover, solid carbon is employed for further experiments. As a result of the necessary addition of Al₂O₃ – because of the corrosivity of FeO_n towards the crucible material during experiments – reaction-inhibiting barrier layers precipitate in the form of spinels during reduction. Foams containing CO_n exert the same effect. From the experimental results, it can be concluded that the reduction of liquid oxides by carbon monoxide or by solid carbon does not consistently obey any law of reaction during the entire process sequence. The essential, decisive parameter for the carbon monoxide blowing experiments is the blowing rate. The experiments performed with the use of solid carbon exhibit the highest reduction rates, on the whole. For the purpose of elucidating the reaction mechanisms, only the experiments conducted by blowing carbon monoxide onto the melt yield clearcut results. After a possible initial steep rise, a reaction of first order is then established, as a first approximation. The further course of the experiment is characterized by covering of the blowing trough. Mass transfer can then proceed only through the spinel layer near the surface, or through the channels between the spinels.     

400kA电解槽降低壳头包结包率方式的研究

壳头包对铝电解正常生产有较大的危害,也会造成操作员劳动强度的增加。其形成的原因主要是电解质成分的剧烈变化、电解质黏度过大、打壳锤头在电解质中停留时间过长和两次打壳之间间隔过短。本文从改变电解槽大壳下料的方式来研究是否可以降低电解槽壳头包结包率,降低工人劳动强度,以及对工艺指标、技术指标有何影响。     

Influence of the Stirring Gas in a 170‐t Ladle on Mixing Phenomena – Formation and On‐line Control of Open‐Eye at an Industrial LD Steel Plant

3D calculations with Computational Fluid Dynamics were carried out to evaluate the flow pattern under industrial conditions with different gas flow rates at the steel plant of Saarstahl AG. The generated flow pattern consists of a circulating loop characterised by an upward flow driven by the argon gas and a downward flow close to the wall on the opposite side of the porous plug in the case of a gas flow rate of 27 STP m³/h. When this high gas flow rate is used, the gas bubbles are taking a straight way from the inlet, but further up the momentum from the circulating steel is affecting the path of the gas bubbles followed by a breakthrough zone at the top surface. Intensive experiments with the 170‐t ladle of Saarstahl AG revealed typical open‐eyes. Large open‐eyes coupled with turbulences in the surface were generated in the case of gas flow rates between 20 and 30 STP m³/h. Intensive turbulences and even smoke formation were identified when a gas flow rate of > 30 STP m³/h was applied. For the investigation of the influence of gas stirring processes on the mixing phenomena samples were taken from the melt immediately after alloying. It could be seen that the analyses of Al, C, Mn and Si increased to the target analyses due to alloying and introduction of Ar through the porous plug. The total time for complete alloying depended on the elements within these experiments. It seemed to be that the alloying time increased in the order of Al, C, Mn and Si. For on‐line control and analysis of open‐eyes in the melt surface during ladle stirring, a BFI image processing system was installed at the steel plant of Saarstahl. It consisted of a conventional digital camera equipped with an infrared filter and coupled to an image processing software. Primary tests showed a slight influence of the open‐eye diameter at the end of the ladle treatment on inclusion densities in the liquid steel and oxidic K0 values of the finished wire rod. Additional experiments were performed but only a small correlation existed between the stirring energy at the end of ladle treatment and the inclusion length index of the applied blue brittle tests. But as soon as an open‐eye came into existence, the inclusion length was higher compared to those heats produced under a closed top slag.     

基于CiteSpace可视化分析下2013~2020年冻融岩石力学热点研究探析

2013年以来,随着寒冷地区资源开发利用与工程建设规模不断扩大,国内外冻融岩石力学研究发展迅速。论文以2013~2020年Web of Science和CNKI数据库收录的冻融岩石力学领域相关论文为数据源,使用文献可视化软件CiteSpace构建了国内外冻融岩石力学研究的关键词共现网络、热点知识演进时区视图和发文高产机构知识图谱,并进行了图谱可视化分析。结合统计结果与知识图谱研究发现：①国内外冻岩力学研究处于快速发展阶段,参与国家和创新性研究成果逐年增加,研究状态火热;②论文在核心期刊与研究机构中的分布集中度较高,企业、科研院所课题研究参与度较低,难以发挥“产学研”综合优势;③热点研究可概括为冻融岩石多尺度力学损伤特性、裂隙岩体冻融损伤机制、岩石本构模型及数值模拟研究;④岩石多场耦合作用、成熟研究成果的工程转化运用将是后续研究的重点关注方向。