【作者】 臧欣阳；

【导师】 姚曼；

【作者基本信息】 大连理工大学 ， 材料加工工程， 2009， 博士

【摘要】 结晶器是连铸机的核心部件,完成将钢液初步凝固成型的任务。结晶器与铸坯之间会发生复杂的热、力行为的作用,结晶器内的传热凝固与摩擦润滑状态决定结晶器的工作状况,最终决定铸坯的表面质量和连铸机的生产能力。当前结晶器监控技术的核心是热学和力学行为的在线检测,其目的是能够实时了解结晶器与铸坯间的传热、摩擦和润滑状况,为实现铸坯质量的在线预测和调控提供帮助和支持。因此,分析和掌握结晶器内热学和力学行为的作用机理,开发和应用基于实测数据的结晶器内传热与摩擦润滑的计算方法,是顺应高效连铸技术发展的根本要求。本文以连铸结晶器为研究对象,围绕着连铸结晶器内发生的传热和摩擦行为展开工作,着眼于推动和促进结晶器热、力行为研究的生产应用,归纳总结以往研究工作的成果与不足,对结晶器内的传热凝固和摩擦润滑行为进行模拟与检测研究。首先,建立基于实测的板坯连铸结晶器传热反问题数学模型,并对实际工况下的结晶器传热与铸坯凝固行为进行分析;其次,推导并建立结晶器-保护渣-铸坯界面摩擦行为的数学模型,对结晶器内的润滑摩擦行为进行讨论;第三,基于液压振动装置驱动的板坯连铸机,研究和建立结晶器摩擦力的瞬态检测模型,并对摩擦力的检测结果进行分析;最后综合模拟计算与检测实验的内容,提出结晶器内传热与摩擦状态联合监测的应用构想,并进行初步的设计与讨论。针对板坯结晶器热电偶的排布特点,研究并建立板坯连铸结晶器传热反问题的数学模型。基于实测温度数据,对结晶器传热与铸坯凝固行为进行了模拟计算,细致分析了实际工况下结晶器内的热流和坯壳厚度分布,以及拉速的影响,并对模型的合理性和传热计算应用的可行性进行了验证。依据摩擦学的基本原理,利用结晶器保护渣的界面模型,界定并划分铸坯表面不同的接触和摩擦状态,同时引入了混合润滑理论,建立了详细描述结晶器-保护渣-铸坯间界面摩擦行为的数学模型。利用基于实测的板坯结晶器传热计算结果,对结晶器与铸坯间的液渣膜厚度分布、保护渣的润滑状况及界面上摩擦应力的变化和影响因素等进行了分析和讨论,并由此提出了可用于生产现场的结晶器保护渣热态润滑摩擦状态的检测方法。基于液压振动装置驱动的板坯连铸机,根据经典的受迫振动理论,对结晶器振动过程中的受力状况进行分析,确定了结晶器摩擦力的检测思路,回归出空振输出力的计算模型,并对模型的合理性及参数的取值规律进行了讨论。根据结晶器摩擦力的检测结果,对实际生产条件下的摩擦力的瞬态行为、其相关参数的变化、振动方式的影响和摩擦力的异常状况等进行了分析,结果表明:正常工况下,瞬态摩擦力近似随结晶器振动速度变化,二者符合较好;漏钢前,摩擦力随振动速度变化的趋势不再明显,摩擦力变化紊乱、无规则。更多还原

【Abstract】 The mould is the core component of continuous caster for primary cooling and initial shell forming of liquid steel.There is a complex interaction of thermo-mechanical behaviors between mould and strand.The states of heat transfer,solidification,friction and lubrication determine the mould working conditions,furthermore,determine strand surface quality and production capacity of continuous caster.At present,the key of mould monitoring technique is on-line detection of thermo-mechanical behaviors,the aim of which is to understand the status of heat transfer,friction and lubrication between mould and strand immediately,in order to provide the support for on-line forecast and control of strand quality.Therefore,it complies with the basic requirement of the development of high efficiency continuous casting technology,to analyze and master the mechanism of thermo-mechanical interaction behaviors in mould,and to develop and apply the calculation methods of heat transfer and friction in mould based on measured data.In this paper,the mould of continuous slab caster is taken as the research object,the study is spread around heat transfer and friction behaviors occurring in the mould.With a view to drive and promote the production application of the study on mould thermo-mechanical behaviors,the achievements and shortage of previous works are summarized,the simulating and detecting studies on heat transfer,solidification,friction and lubrication behaviors are conducted.Firstly,based on the measured data of mould temperature during slab continuous casting,an inverse problem model is built,and the mould heat transfer and the strand solidification in the practical production are analyzed.Secondly, the mathematical model of friction behavior on mould/slag/strand interface is derived and built,and the lubrication behavior in mould is discussed.Thirdly,based on the slab caster equipped with hydraulic oscillators the transient detecting model of mould friction is researched and built,and the detection results of mould friction are analyzed.Finally, integrating the contents of simulating calculation and detection experiment,the application idea of combined monitoring of heat transfer and friction states in mould is put forward with primary design and discussion.An inverse problem model of mould heat transfer in slab continuous casting is researched and built aiming at the installation characteristics of thermocouples in slab mould. Based on measured temperature data the behaviors of mould heat transfer and strand solidification are simulated,and then the distributions of heat flux and shell thickness,and the effect of casting speed in the practical production are detailedly analyzed.And the rationality and feasibility of heat transfer calculation is validated.The mathematical model to describe friction behavior on mould/slag/strand interface is built with introducing mixed lubrication theory by well defined and divided different contacting and lubricating states on strand surface.Using the calculation results of mould heat transfer based on measuring data mentioned above,the thickness distribution of liquid slag film between mould and strand,slag lubrication status,frictional stress variation on the interface and their influence factors are analyzed.After that a detecting method of thermal lubrication and friction state of mould fluxes is put forward,which can be used for production field.On the basis of the slab caster equipped with hydraulic oscillators and the classical forced oscillation theory,the mould force situation during oscillation is analyzed and the detection idea of mould friction is determined.The calculation model of cylinder force at empty state is regressed,and the rationality and the range of parameters are discussed.Based on the detecting results of mould friction,frictional transient behavior,relative parameters variation,effect of oscillation mode and abnormal status are analyzed.The results show that the transient friction approximately changes with oscillation velocity during the normal state, both of which coincide well;abnormal fluctuation of friction would occur before the breakout with bad coincidence between friction and velocity.更多还原