Electromagnetic Dam in Twin-Roll Strip Caster

The electromagnetic dam （EMD） in twin-roll strip caster was simulated with FEM. The results show that the direction and magnitude of Lorentz force distributing in the EMD changed in a period. The negative part is about 30% of the positive part, and the acting time of the negative force is about 40% of a period. In order to prevent the liquid steel from leaking efficiently, the distance between two poles should be the same from the top to the bottom of the EMD, otherwise the magnetic induction will be very small at the top and large at the bottom.

Wear analysis of a side dam in twin-roll strip casting

Reducing wear on a side dam can prolong the casting operation life of a twin-roll strip casting process,thus reducing production cost and improving casting stability.To lengthen the service life of the side dam,it is necessary to understand the wear performance of the side dam material.To investigate the wear behavior mechanism of the side dam,in this study,the UMT-2 friction and wear tester was used to determine the relationship between the wear rate of the side-dam material and various parameters.Based on the roughness of the contact area between the side dam and the end of the casting rolls as well as on the amount of deformation of the side dam,which was derived using a thermal-deformation simulation model,the reasons for the uneven wear of the side dam were obtained.

Effect of Seismic Permanent Deformation on Safety and Stability of Earth-Rock Dam Slope

In order to study the effect of seismic permanent deformation on the safety and stability of earth-rock dam, the permanent deformation is considered as the non-design permanent load, and the stress-strain hysteresis curve is also considered when the earth is under cyclic load. The research work can make the calculation results of plastic collapse more accurate by including the effect of the post-earthquake degree of plastic deformation on the stability of the earth-rock dam, and the dam safety factor decreases from 2.50 to 1.90 after the magnitude-8 earthquake. Moreover, the research work will also improve the design of the earth-rock dam under abnormal operating conditions.

Dynamic Risk Assessment Index System for Earth-Rock Dam during Construction

During the construction of earth-rock dam,mutual exclusive construction goals such as quality,safety,progress and cost all have influences on each other,with risk factors being everchanging as the construction progresses.Accurate identification of the risk factors,as well as clearing any possible effect that any risk factors might have on the construction project is the key and foundation to our cooperative control of the construction goals.According to the construction planning of earth-rock dam,the hall3 D structure was used to identify the potential changes of risk factors,and the possible means of any risk factors to interfere with the construction goals.The dynamic risk assessment index system is established by deploying the WBS-RBS(work breakdown structurerisk breakdown structure)method,aiming at the construction goals of earth-rock dam.The case study shows that the index system is very effective at risk management of earth-rock dam during construction,and relatively practicable.

Study on life-cycle risk management of high earth-rock dam project

Based on advanced computer technology, internet of things （lOT） technology, project management con- cept and professional technology and combined with the innovative theories, methods and techniques in earlier hy- dropower projects, the life-cycle risk management system of high earth-rock dam project for Nuozhadu project was developed. The system mainly includes digital dam, three-dimensional design, construction quality monito- ring, safety assessment and warning, etc, to integrally manage and analyze the dam design, constructional quality and safety monitoring information. It realized the dynamic updates of the comprehensive information and the safe- ty quality monitoring in the project life cycle, and provided the basic platform for the scientific management of the construction and operation safety of high earth-rock dam. Application in Nuozhadu earth-rock dam showed that construction safety monitoring and warning greatly helped accelerate the construction progress and improve project quality, and provided a new way for the quality safety control of high earth-rock dam.

Damage Mechanism and Countermeasures of Carbon Bonded Refractories for Continuous Casting

The long nozzle,stopper,and submerged entry nozzle play an important role in continuous casting. They are of the similar composition and are mainly damaged by liquid steel thermal shock which leads to immediate cracks or fracture in their combined area because of the thermal mechanical properties mismatch,or damaged by corrosion on their interface. The failure mechanisms are the thermal shock damage and continuous reaction corrosion. High efficiency and long life of the long nozzle,stopper,and submerged entry nozzle can be realized by optimizing the thermal mechanical properties,the key erosion step,and the combination match.

绿塘整体浇筑堆石混凝土拱坝施工期温度仿真研究

【目的】绿塘大坝是一座不分横缝、整体浇筑的堆石混凝土拱坝,旨在解决坝体分缝过多而带来的施工干扰大、速度慢以及堆石率低等问题。为深入探究这种新拱坝型式的温度场分布特征与应力变化规律,得到堆石混凝土坝体不分缝或少分缝的理论依据,【方法】基于实测资料开展有限元温度仿真计算,考虑上游防渗层及预制混凝土块模板、混凝土水化反应及弹性模量增长、徐变等,采用结构多场仿真与非线性分析软件SAPTIS模拟整体浇筑拱坝的分层拱圈浇筑全过程,并分析坝体温度场与应力分布规律。【结果】结果显示:绿塘大坝施工期的混凝土水化温升较低,约3~10℃,部分高温月份浇筑的混凝土温升后能达到38.6℃;施工期拱向拉应力普遍小于0.8 MPa,仅上游自密实混凝土防渗层的局部应力达到1.5 MPa,预制混凝土块模板起到辅助吸热和力学约束作用;横缝对拱坝上游面的应力改善较为明显。【结论】结果表明,堆石混凝土拱坝采用不分横缝、全断面整体上升浇筑的型式是可行的,但建议上游防渗层设置短缝和高温季节采取合适的温控措施,该坝型对促进快速筑坝技术发展具有重要意义。

复杂精密薄壁DAM盒体批量化高效生产工艺

针对某DAM组件盒体的结构特性复杂、精度要求高,以及生产周期短的特点,结合工艺分析,提出采用精密熔模铸造和数控精密加工相结合的工艺方案。通过选用合适的铝合金材料、合理的工艺措施,适应了该产品的批量化高效生产要求,缩短了加工周期,降低制造成本,提高了成品率,并保持尺寸精度、一致性和互换性,最终满足设计要求。

基于边开挖边浇筑的水库大坝盖板混凝土施工技术

边开挖边浇筑的水库大坝盖板混凝土施工技术是一种以开挖为基础、同时进行浇筑和养护的施工技术,为探讨基于边开挖边浇筑的水库大坝盖板混凝土施工技术,结合黄石沟沉沙调蓄水库的实际情况,立足边开挖边浇筑的优势,分析水库大坝盖板混凝土施工技术的应用要点。结果表明,该技术可以在保证大坝结构安全的前提下,加快施工速度和质量,提高施工效率和经济效益,值得在类似工程中推广和应用。

Characteristics and factors that influenced damage to dams in the M_s 8.0 Wenchuan earthquake

Based on raw data from dams damaged in the Wenchuan earthquake, including many that were severely damaged, characteristics and factors that influenced the damage are discussed in this paper. Findings from this study include： severely damaged dams were densely distributed along the seismologic fault; small dams, especially small earth-rock dams, had the most serious damage that was caused by a variety of factors; the most serious damage was caused by seismic waves; damage was aggregated by aftershocks; and the extent of the damage patterns increased with the seismic intensity. Damage patterns varied in different intensity zones and cracking was the most common type of damage. Most of the dams had a good base with relatively high bearing capacity, and the walls of the earth-rock dams were mostly of clay soil. This type of base and body material mitigated some of the damage to dams. Reservoir maintenance and other factors also have a significant impact on the seismic safety of the dam. Finally, some recommendations to reduce seismic damage to dams are proposed.

Hydraulic simulation of the feeding system in the strip casting process

A 1：1 water model of a twin-roll strip caster was set up based on the Froude number（Fr） and Reynolds number （Re） similarity criteria. Fluctuation and the mixing effect in the molten pool of twin-roll strip casting process were analyzed through hydraulic simulation. The height of the fluctuation of the liquid pool surface and the residence time were measured by DJ800 multifunctional monitor under different process conditions. The results show that the casting velocity, the insertion depth and the pool level have a great effect on the fluctuation.

薄带连铸侧封技术的研究现状及发展趋势

总结了国内外薄带连铸侧封技术(包括电磁侧封技术、气体侧封技术、固体侧封技术)的研究现状,重点介绍了固体侧封板的材质(主要有熔融石英质、高铝质、锆英石质、镁质、铝碳质、氮化硼质等),并展望了侧封技术的发展趋势和方向。

两流板坯连铸中间包控流装置的优化

在相似理论的基础上,按照1∶3的比例建立了"两流板坯连铸中间包"水力学模型,通过挡墙与挡坝不同高度及位置的组合来优化中间包的内部结构并确定出最佳设计方案。试验结果表明:优化后能将原型中间包的滞止时间由83 s延长到97 s,平均停留时间由296 s延长到432 s,死区由46%减小到21%,电导率微观波动值由0.04 ms/cm降低到0.025 ms/cm以内。

整体浇筑堆石混凝土拱坝拱梁分载法分析研究

贵州省遵义市地处气候温和地区,为了充分发挥堆石混凝土拱坝的优势,在取消振捣/碾压和冷却水管温控措施的基础上,简化坝体构造与施工、加快施工进度,在保障工程建设质量和安全的前提下,提出了不分横缝,整体浇筑的堆石混凝土拱坝。本文针对绿塘、龙洞湾、沙千和风光4座整体浇筑堆石混凝土拱坝,采用拱梁分载法进行应力分析,对拱圈封拱温度的选取,自重荷载处理方式,坝体与地基材料参数对拱坝应力的影响等开展研究,对4座拱坝的安全性进行论证,建议了辅助温控措施,并提出了整体浇筑堆石混凝土拱坝拱梁分载法应力复核方法及其控制标准:应根据拱坝实际浇筑温度估算拱坝每个拱圈的计算封拱温度,参照混凝土拱坝设计对坝体与地基材料参数进行取值,采用拱梁分载法进行拱坝应力复核,相应的允许应力标准初步可按照1.5~2.0 MPa控制。本文提出的分析方法除可以应用于整体浇筑堆石混凝土拱坝以外,对整体浇筑的碾压混凝土拱坝和砌石拱坝也有重要参考价值。

双辊薄带钢铸轧熔池电磁侧封模拟试验

报道双辊薄带钢铸轧熔池电磁侧封低熔点合金模拟试验研究结果。在额定功率 60kW、频率 2 5 0 0Hz的电源下 ,成功实现对高 10cm金属熔池的侧向电磁约束与封堵。

双辊薄带铸轧数值模拟研究现状及展望

由于铸轧过程复杂,工序高度凝聚且工艺参数间联系紧密,其中一些重要的现象无法通过现有实验条件进行测量,因此数值模拟方法成为探寻铸轧规律的一种有效方式,已经在有色金属以及钢铁铸轧领域得到广泛应用。本文对近年来采用数值模拟方法针对铸轧过程中熔池、铸辊、浇注布流系统、带坯组织及侧封板方面的研究应用工作进行了总结,并对电磁场、流场、温度场及应力、应变场等多物理场耦合计算的数值模拟技术在铸轧研究中的应用进行了展望。

双辊铸轧薄带钢侧封板材料评价及热应力有限元模拟

通过对双辊铸轧薄带钢工艺中侧封技术的研究,分析了侧封板产生损耗和破碎的原因,并采用两种侧封板结构整体式和组合式进行了试验研究;试验证明组合式侧封板对提高铸轧过程稳定性和改善侧封板的使用寿命具有良好效果。通过不同钢种的薄带铸轧试验对侧封板的腐蚀情况进行了研究,同时采用了不同材质耐火材料制作的侧封板进行了对比分析,得出氧化锆质侧封板综合性能最好。采用ANSYS有限元分析软件,分析了侧封板在铸轧过程中温度场和热应力场,由此解释侧封板产生裂纹的原因。

双辊铸轧薄带钢侧封板热应力的数值分析

采用有限元法模拟了双辊铸轧薄带钢工艺中侧封板的三维温度场和热应力场。通过对侧封板的温度和应力的耦合数值模拟 ,得出了在铸轧过程中侧封板的温度和热应力的分布规律。根据热应力分析了侧封板裂纹产生机理 ,得出侧封板产生裂纹的位置与实验结果相吻合 ;同时分析了不同预热温度对侧封板温度和热应力分布的影响 。

薄带钢铸轧电磁侧封装置及其参数设计

对薄带钢双辊铸轧电磁侧封的电磁发生装置参数及辊边结构进行了计算和分析 ;结果表明 ,对于高度为 0 .2m的熔池的电磁侧封 ,参数选取辊半径 0 .6m、电流 50 0 0～ 1 0 0 0 0A、线圈匝数 3～ 5匝 ;辊边开槽时 ,增大槽口宽度及考虑用高磁阻材料封堵槽口 ,有助于使磁场向熔池侧壁集中。

金属薄带双辊连铸复合式电磁侧封的物理模拟

针对薄带双辊连铸的辊端金属液侧封问题,采用低熔点合金物理模拟实验,研究单纯的电磁侧封、电磁场复合有机玻璃挡板侧封、电磁场耦合内置或外置铁芯的耐材挡板侧封4种方式下的磁感应强度分布特点和侧封效果。结果表明:电磁场耦合内置铁芯挡板的侧封方式效果最好,可将金属液侧封高度提高3.3倍,且金属液的侧封高度随电流强度线性递增。同时还观察和分析侧封过程中金属液面波动现象。