板坯连铸大辊径铸轧辊不同冷却方式模拟

Simulation on different cooling methods of large roll diameter casting rolls in slab continuous casting

连铸过程借鉴轧钢过程的轧制大压下思路,在连铸二冷区对高温铸坯单点施加不低于20 mm大压下量是解决铸坯中心疏松等内部缺陷以及提高钢板性能的重要技术手段,也是近年来连铸技术研究的热点领域。实施大压下功能需要大辊径的铸轧辊,辊子与二冷区板坯连续、高温、低转速接触,服役环境恶劣,铸轧辊的冷却方式是影响大压下效果、辊子寿命及铸坯表面质量的关键因素。采用ABAQUS有限元软件构建铸轧辊二维传热模型,模拟铸轧辊“双面喷水”“、单面喷水”“、单面喷2倍水”3种冷却方式下辊面及内部整体温度变化规律,可知“双面喷水”和“单面喷2倍水”2种冷却方式下,一个辊动周期内铸轧辊辊内温度不超过100℃所占比例相等,即辊子冷却效果相当,可以保证整个铸轧辊多数时间在低温工作状态,可提高辊子寿命。工业试验中“,双倍喷水”冷却方式的冷却水会大量滴落存积在大压下前铸坯表面,局部温度快速降低进入高温低塑性区,实施大压下后易造成表面裂纹。因此,实际生产采用“单面喷2倍水”的冷却方式,解决了大压下前铸坯表面冷却水滴落存积的问题,铸轧辊使用寿命高,铸坯无裂纹率。该研究对大辊径铸轧辊的冷却模式设计提供了很好的思路,为二冷区板坯大压下工艺技术的开发及应用打下了基础。

Applying a large reduction amount of≥20 mm to a single point of high temperature casting billet in the secondary cooling zone of continuous casting is an important technical means to solve the internal defects such as loose center of casting billet and improve the performance of steel plate,and it is also a hot field of continuous casting technology research in recent years.To implement the function of large reduction,the casting roll with large roll diameter is required.The rolling contact with the slab in the secondary cooling zone is continuous,high temperature and low speed,and the service environment is harsh.The cooling mode of the casting roll is the key factor affecting the effect of large reduction,the life of the roll and the surface quality of the casting slab.ABAQUS finite element software was used to build a two-dimensional heat transfer model of casting roll,and the overall temperature variation rule of casting roll surface and inside under three cooling methods of"double-sided water spraying","single-side water spraying"and"single-side water spraying twice"was simulated.Under the two cooling methods of"double-sided water spraying"and single-side spraying twice water",the proportion of the inner temperature of the casting roll≤100℃ within a rolling cycle is equal,that is,the cooling effect of the roll is equivalent,which can ensure that the entire casting roll works at low temperature most of the time,and can improve the life of the roll.In the industrial experiment,the cooling water of the"double water spray"cooling method will drop a large amount of water on the surface of the casting billet before high pressure,and the local temperature will drop rapidly into the high temperature and low plasticity zone,which is easy to cause surface cracks after the implementation of high pressure.Therefore,the cooling method of"single side spraying twice water"is used in the actual production,which solves the problem of cooling water dripping on the surface of the casting billet before large pressure,and has high service life of the casting roll and no crack rate of the casting billet.It provides a good idea for the design of the cooling mode of thelarge roll diameter casting roll,and lays a foundation for the development and application of the slab heavy pressing technology in the secondary cooling zone.