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传热过程决定着板栅连铸结晶器能否连续稳定地生产出合格质量的连铸板栅,根据热力学第一定律和傅里叶定律(热传导定律)对板栅连铸结晶器的热量传递进行了研究。依据板栅连铸结晶器实际结构简化模型,分别建立了冷却油、端盖以及空气稳态复合传热模型,高温铅液、连铸动模外筒以及冷却油的稳态复合传热模型,连铸动模内部冷却油的放热计算模型,进而建立了板栅连铸结晶器传热动态平衡方程;为了指导生产实际,建立了运行过程操作函数。通过板栅连铸结晶器传热过程的分析研究,对提高板栅连铸的连续稳定生产并实现板栅连铸结晶器的全自动温度控制具有一定的指导意义。 相似文献
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Eun-yi Ko Kyung-Woo Yi Joong-kil Park Jung Wook Cho Ho-Jung Shin 《Metals and Materials International》2010,16(2):281-288
In this study, we establish a 3-D numerical analysis model to analyze the thermal behavior and to obtain the detailed heat
transfer coefficient of a copper mold in a continuous casting system. This heat transfer coefficient changes according to
variations in the mold geometry or cooling system. For increased flow speeds of the cooling water, the heat transfer coefficient
also increases, but the rate of increase for the coefficient diminishes at higher flow speeds. As the thickness of the mold
between the melt and the cooling water slots increases, the mold’s heat transfer coefficient decreases. However, the uniformity
of the heat transfer coefficient improves with greater thickness. The effect of distance between cooling water slots on the
mold’s heat transfer coefficient is also observed. Calculations show that greater distances between cooling water slots decrease
the heat transfer coefficient. 相似文献
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连铸电磁搅拌结晶器内钢液流动、传热、传质和凝固行为十分复杂且对铸坯质量影响巨大,为了进一步揭示电磁搅拌结晶器内多物理场传输行为及其相互影响规律,建立了电磁场作用下三维多物理场耦合连铸凝固模型,模拟研究了结晶器电磁搅拌对帘线钢82B小方坯连铸过程的影响。结果表明,随着搅拌电流强度增大,钢液流动加强;结晶器出口附近铸坯中心纵向流速先减小,进而流速反向,之后反向的流速增大,促进热量散失,加剧了小方坯皮下负偏析,同时促进了钢液池溶质浓度提高。当搅拌电流为280 A时,搅拌器中心铸坯横截面上最大切向速度达到0.23 m/s,距离弯月面1.5 m位置,负偏析低谷碳的质量分数为0.706%,铸坯中心碳的质量分数达到了0.872%。 相似文献
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EXPERIMENTAL RESEARCH AND NUMERICAL SIMULATION OF MOLD TEMPERATURE FIELD IN CONTINUOUS CASTING OF STEEL 总被引:1,自引:0,他引:1
X.S. Zheng M.H. Sha J.Z. Jin 《金属学报(英文版)》2006,19(3):176-182
Mold is the heart of the continuous casting machine. Heat transfer and solidification in a water cooled mold are the most important factors during the continuous casting of steel. For studying the temperature distribution of a mold wall, a simulated apparatus of mold was designed and experiments were performed by it. The measured results indicated that the mold wall temperature approaches the temperature of cooling-water. An equivalent thermal-conductivity coefficient was proposed and deduced on the basis of the conclusion of the experiments. This coefficient was applied to solve the heat transfer between the melt and cooling water, and to characterize the heat transfer capacity of the mold. By this equivalent thermal-conductivity coefficient, it is very easy and convenient to numerically simulate the solidification process of continuous casting. And the calculation results are in agreement with the experiments. The effects of casting speed and water flow rate on the mold temperature field were also discussed. 相似文献
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A mold flux is widely used to modify heat transfer rates in continuous casting, and crystallization of a mold flux has been
identified as a primary factor that influences heat flux from the strand to the mold. By using an infrared radiation emitter,
a radiative heat flux was applied to a copper mold covered with solid mold flux disk to simulate the heat transfer phenomena
in continuous casting. By this technique it is possible to have a liquid layer, a crystalline layer and a glassy layer in
contact with one another and, by varying the energy input, it is possible to study the dynamic nature of the film and its
effect on the radiative and overall heat transfer rate. A general heat transfer model was also developed to allow the prediction
of the effect of varying the thickness of the three potential layers in the flux film. 相似文献
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Fluid flow, heat transfer and solidification of steel in the mold are so complex but crucial, determining the surface quality of the continuous casting slab. In the current study, a 2D numerical model was established by Fluent software to simulate the fluid flow, heat transfer and solidification of the steel in the mold. The VOF model and k-ε model were applied to simulate the flow field of the three phases(steel, slag and air), and solidification model was used to simulate the solidification process. The phenomena at the meniscus were also explored through interfacial tension between the liquid steel and slag as well as the mold oscillation. The model included a 20 mm thick mold to clarify the heat transfer and the temperature distribution of the mold. The simulation results show that the liquid steel flows as upper backflow and lower backflow in the mold, and that a small circulation forms at the meniscus. The liquid slag flows away from the corner at the meniscus or infiltrates into the gap between the mold and the shell with the mold oscillating at the negative strip stage or at the positive strip stage. The simulated pitch and the depth of oscillation marks approximate to the theoretical pitch and measured depth on the slab. 相似文献
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针对连铸过程中时常发生的坯壳和结晶器铜板壁黏结情况,分析了保护渣性能、结晶器流场、保护渣充填操作、中间包温度、钢水纯净度等造成黏结的各种因素,通过采取相应措施,大大减少了黏结情况。 相似文献
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为了提高保护渣在CSP生产包晶钢过程中的匹配性,针对CSP工艺的连铸特点及包晶钢的凝固特点,总结了两者对保护渣理化性能的要求;对工厂CSP包晶钢连铸保护渣1号进行优化得到保护渣2号,并通过单双丝热电偶技术、高温旋转黏度仪、扫描电镜对其熔化性能、传热性能、黏流性能、结晶性能展开了具体表征与评价。研究结果表明,保护渣2号的润滑性能与控热能力均优于保护渣1号,较好地解决了润滑与传热的之间的矛盾;除此以外,保护渣2号的熔化温度较低,熔速较快,具有良好的熔化性能。因此,保护渣2号的理化性能优异,满足了CSP包晶钢连铸保护渣的设计与性能要求。 相似文献
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薄板坯连铸结晶器铜板的三维传热分析 总被引:2,自引:0,他引:2
建立了薄板坯连铸结晶器铜板的三维传热数学模型,特别是对结晶器铜板冷面的水槽和背板部分采用了交替配置不同的边界条件处理,利用Visual Fortran语言自编程序计算结晶器铜板温度场.通过对一典型薄板坯连铸结晶器铜板模拟分析,发现铜板热面温度呈现云层分布,冷面温度呈冰柱状分布.分析了各种工艺参数(拉速、铜板厚度、冷却水流速等)对结晶器铜板温度场的影响,典型位置上的计算结果与现场测量数据符合较好,为优化生产工艺参数和结晶器设计提供理论依据和实际参考数据. 相似文献
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随着国内高拉速连铸机日渐增多,结晶器铜板的失效已经变为以热疲劳裂纹形式为主。采用ANSYS数值模拟软件对结晶器铜板温度和热流密度分布规律进行了研究。计算结果表明,结晶器铜板的温度分布和生产中热疲劳裂纹的形式不相同;铜板弯月面区发生热裂失效的主要原因是在一定温度下,上下运动的热流密度的集中区即“能量流”撕裂了铜板,因此减小结晶器铜板弯月面处的热流密度,有可能减少铜板热裂纹的产生。设计均匀传热、减少铜板和连铸坯裂纹生成的结晶器是未来技术发展的方向。计算结果表明,沟槽结晶器铜板表面刻划沟槽后可以减弱弯月面区域热流密度,改善结晶器铜板的不均匀传热状况。 相似文献
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The heat transfer during the casting solidification process includes the heat radiation of the high temperature casting and the mold, the heat convection between the casting and the mold, and the heat conduction inside the casting and from the casting to the mold. In this paper, a formula of time step in simulation of solidification is derived, considering the heat radiation, convection and conduction based on the conservation of energy. The different heat transfer conditions between the conventional sand casting and the permanent mold casting are taken into account in this formula. The characteristics of heat transfer in the interior and surface of the casting are also considered. The numerical experiments show that this formula can avoid computational dispersion, and improve the computational efficiency by about 20% in the simulation of solidification process. 相似文献
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Element parameters including volume filled ratio, surface dimensionless distance, and surface filled ratio for DFDM (direct finite difference method) were proposed to describe shape and location of free surfaces in casting mold filling processes. A mathematical model of the filling process was proposed specially considering the mass, momentum and heat transfer in the vicinity of free surfaces. Furthermore, a method for gas entrapment was established by tracking flow of entrapped gas. The model and method were applied to practical ADC1 high pressure die castings. The gas entrapment prediction was compared with the fraction and maximum size of porosities in the different casting parts. The comparison shows validity of the proposed model and method. The study indicates that final porosities in high pressure die castings are dependent on both gas entrapment during mold filling process and pressure transfer within solidification period. 相似文献
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NUMERICAL SIMULATION OF CASTING PROCESS 总被引:1,自引:0,他引:1
L.L. Chen R.X. Liu H.T. Lin College of Materials Science Engineering Huazhong University of Science Technology Wuhan China 《金属学报(英文版)》2000,13(2):764-769
1.IntroductionThemodellingofcasting,whichmeansmostlycomputernumericalsimulationofcast...lug,isaimedatanalysingpracticalfoundryproceduresundercomputervirtualenvironment,includingfillingprocess,solidificationprocessandstressdistributionofcasting.Withthehelpofthespecialtechnique,itbecomeseasytoevaluatetheinfluenceofmajorfactorsandpredictcastingdefects.Therefore,thepowerfultoolcanbeadoptedtooptimizefoundrytechnologyandreducecastingdefects.Foundrynumericalsimulationresearchbeginsin1962,andhasagreat… 相似文献
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在钢的连铸过程中,钢水在结晶器内的凝固对铸坯的产量和质量均有很大影响,几乎所有的铸坯表面缺陷均形成于结晶器内。近年来,随着连铸拉速的增加及对铸坯表面质量要求的提高,有关结晶器冷却、传热对钢水的初始凝固及表面纵裂纹影响的研究成为连铸科学研究的重点。结晶器壁热流不均是纵裂纹产生的有利环境,保护渣控制传热为常用的措施。薄板坯浇铸时由于拉速高,为获得表面无缺陷铸坯,对保护渣控制传热的要求更高,同时也需协调保护渣的润滑功能。通过生产试验,研究比较3种碱度保护渣(CaO/SiO2分别为1.06、1.26和1.48)对薄板坯结晶器平均热流量的影响,发现与低碱度保护渣相比,使用高碱度保护渣时,结晶器热流量最低,有利于实现弱冷却,形成均匀凝固坯壳,在一定拉速条件下浇铸裂纹敏感钢种时有助于获得良好表面质量的铸坯。 相似文献