Heat Transfer Characteristic of Molten Pool for Twin-Roll Strip Casting

Body-fitted coordinate transformation equation was deduced and used to generate the body-fitted grids of molten pool for twin-roll strip casting.The orthogonality of the grids on the boundary was modified by adjusting source item.The energy equation and the boundary conditions were transformed from physical space to computational space.The velocity field model proposed by Hirohiko Takuda was used to calculate the temperature field of molten steel,and the influence of technical factors was also discussed.

Design of a high-precision twin-roll strip caster

During strip casting,the thickness deviation of casting strip directly affects the quality of the hot-rolled sheet because the casting strip needs to be rolled only once.To accurately control the gap between casting rolls and reduce the thickness deviation of the casting strip,a conceptual design of a prestressed twin-roll caster is proposed herein;this caster involves the setting of a constant pressure balancing cylinder between the chocks of two casting rolls.The balancing cylinder hydraulic system adopts a three-way servo valve that controls the hydraulic cylinder.The parameters of the hydraulic power components are determined using the principle of optimal power matching,and the hydraulic system model of the balancing cylinder is thus established.The dynamic analysis and simulation of the hydraulic system are performed using finite element model to obtain relevant evaluation indexes.Finally,the hydraulic system is corrected using proportional-integral-derivative (PID) correction to achieve a well-controlled effect.Thus,the engineering requirements of the strip casting process can be met.

双辊薄带铸轧熔池内流场和温度场数值模拟

以带宽1000 mm,辊径600 mm的双辊薄带铸轧过程为研究对象,基于Fluent软件,建立了薄带铸轧熔池三维有限体积模型,对其中钢液流动状态及传热进行数值模拟,并考察了新型浇铸系统结构、布流器开孔倾角、铸轧速度、过热度及冷却强度对铸轧AISI304不锈钢熔池的流场和温度场的影响.结果表明,采用浸入式水口,多孔布流器,导流坝以及分流体组合的新型浇铸系统,且水口浸入布流器熔池内,布流孔向上倾角15o^18o,铸带速度在60~80m/min,熔池自由液面湍流动能最大值为0.0175 J/kg,熔池表面温差低于20 K,钢液与铸轧辊接触面能稳定形成大于0.6 mm的凝固坯壳.

双带式非晶带材连铸熔池热流耦合数值模拟

以制备新型双带式非晶锆合金带材连铸机的熔池为研究对象,基于VOF算法,考虑了外界气体层与熔池自由液面的相互作用,建立了熔池内流动和传热的三维耦合模型,对比分析了采用传统楔形布流系统和新型布流系统时熔池流场和温度场的分布情况。结果表明,采用新型布流系统进行浇注时,熔池侧封区域的自由液面更为平稳且熔池出口处的轴向最大温差从30℃减小到15℃左右,验证了新型布流系统的合理性。