【作者】 胡仕成；

【导师】 钟掘；

【作者基本信息】 中南大学 ， 机械设计及理论， 2005， 博士

【摘要】 本论文以铝连续铸轧过程为对象系统分析了金属[液—固]、[固—固]界面接触热导的产生机理,以界面热流中的电子、声子行为为基本依据,对影响实际接触界面传热的主要因素进行了分析,探讨了不同表面氧化膜厚度下的界面传热机制;分析了铸轧工作界面传热的特点,推导了接触热导的计算模型;用热脉冲法实现了塑性变形下的接触热导测试,实验研究了压力、界面介质与氧化膜对热导的影响;建立了铸轧过程温度场和轧制力的仿真模型,对铸轧过程的工艺规律进行了仿真分析。 研究工作主要包括如下几个部分: 1.运用固体物理学的金属电子理论结合金属准原子模型,建立了基于能量载子的金属实际接触区接触热导计算模型,定量分析了界面温度、氧化膜厚度与势垒高度、费米能及配副材料声学失谐对接触热导的影响,探讨了不同氧化膜厚度下的微观传热机制。 2.分析了铸轧过程凝固界面接触热导的影响因素,提出了固相率的计算模型,从铸轧实际生产过程热平衡与传导的宏观参数,获得铸轧界面接触热导的统计值。 3.分析了在材料发生屈服变形条件下,影响界面实际接触面积的主要因素,得到了轧制界面接触热导的理论模型。 4.实验研究了X合金材料不同厚度表面氧化层的接触热导,分析了影响X合金表面氧化膜厚度的主要因素;通过自制夹具,实现了用激光热导仪测试试件发生塑性变形条件下的接触热导,研究了界面介质、氧化膜、粗糙度及接触压力对接触热导的影响,建立了塑性变形下的接触热导实验研究模型。 5.建立了铸轧过程温度场和轧制力的计算模型,编写了计算程序,对国内两种铸轧机进行了实例分析,通过与现场测试数据的对比分析,验证了计算程序和边界条件的可靠性。 本论文的研究工作,可以为铸轧机设计、铸轧工艺控制和铸轧过程工程热物理规律的技术实现提供理论参考,期望对铝装备技术的发展有所稗益。更多还原

【Abstract】 Making continuous roll-casting process of aluminum its chief concern, this paper analyzes the mechanism of thermal contact conductance (TCC) at the interface between liquid-solid or solid-solid metals systemically. The main factors affecting heat transfer between real contact interfaces, the physical mechanism of interface heat transfer under different surface oxide film scale as well as the characteristics of heat transfer at the work interface of roll-casting are analyzed. Then the computation model of TCC is deducted. The TCC test under plastic deformation is realized through laser pulse methods. The influence of pressure, the mediums and oxide film on thermal conductance are studied by experiments. Besides, the simulating model of temperature field and rolling force in the process of roll-casting is established. The technical rules of roll-casting process are analyzed. The study is organized as follows:Firstly, combining the metal electronics theory in solid physics with metal semi-atom model, the computation model of TCC in the real metal contact zone based on the energy carriers is established. Then the influences of interface temperature, height of potential barrier of oxide film, Fermi energy and acoustic mismatch of contacted materials on TCC are analyzed quantitatively. The heat transfer micro-mechanisms under different scales of oxide films are discussed.Secondly, the TCC’s influence on metal solidification is explored by way of enthalpy. The paper puts forward the computation model of solid ratio in the roll-casting process. Then the statistical value of TCC at the roll casting interface is obtained from the macroscopical parameters of roll casting production process.Thirdly, the main factors affecting the real contact surface area on condition that the materials under yield deformation are discussed and the theoretical model of the TCC in rolling surfaces is established.Fourthly, the X alloy’s TCC of the surface oxide layer with differentthickness is experimented and the main factors affecting the thickness of surface oxide film of X alloy are discussed. Using homemade clamp, we have realized the TCC’s test by laser conductivity apparatus when the specimens are under plastic deformation, studied the influence of interface mediums, oxide film, roughness as well as contact pressure on TCC, thus established the experimental research model of TCC under deformation.Fifthly, the computation model of the temperature field and rolling force during the roll-casting process are established. We’ve compiled a computation program and made instance analysis on two different types of domestic roll-casting machine. By comparison with the field data, the computation model and boundary conditions are proved reliable.The study done in this paper can provide reference for the design of roll-caster, the control of roll casting technics and the technically realization of heat transfer disciplinarian at the roll casting process. It is expected that the study can be benefit to the development of equipment and technology of aluminum roll casting.更多还原