The Research Of Heat Transfer Behavior At Metal Rheologic Interface Of Continuous Roll-casting Process

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.