金属板高速覆膜机理与关键控制技术

Polymer-coated steel is a new type of metal packaging material instead of tinplate, which has broad application prospects. The research and development of chinese polymer-coated steel started soon and there is a clear gap compared with foreign advanced level. The newly built polymer-coated steel production line of Baosteel is used as the modeling object and verification platform.This project focuses on the key issues of the thermal behavior of polymer-coated steel melting process, the flow spreading and filling process of molten plastic in meso-scale, the coated roller pressure at high-speed, the structure dynamics and stability of coated roller, the vertical film thickness accuracy and transverse thickness distribution of plastic film products and so on. The study reveales the physical mechanism and regularity of the high-speed melt coating process, and obtains the factors affect heat transfer and temperature distribution of the plastic film, the plastic film melt flow, the interface real contact area and the pressure and film thickness of the interface. Also the project studies and establishes the key control technology of high-speed coating process and film quality, including the initial temperature, substrate surface microtopography, the requirements and setting methods of roller pressure, the prediction of plastic film thickness, roller pressure, the calculation method and model of plastic film thickness, and the control strategy and technology of roller pressure and film thickness of the finished product. In order to meet the existing domestic units to achieve a substantial increase in the rate of film technology and ensure the polymer-coated steel producted in a high-speed,high-quality,stable way, and catch up with foreign advanced level, this project provides theoretical guidances and technical supports for chinese self-developed polymer-coated steel products.

覆膜铁是一种替代马口铁的新型金属包装材料，应用前景广阔。我国的覆膜铁研发起步不久，与国外先进水平存在明显差距。本课题拟以宝钢新建成的覆膜铁生产线为建模对象和验证平台，围绕覆膜铁熔融复合过程热行为、细观尺度熔融塑料流动铺展填充过程、高速覆膜辊压力、覆膜辊系结构动力学行为、塑料膜运行稳定性、成品纵向膜厚精度与横向膜厚分布等关键问题，研究揭示高速熔融覆膜过程的物理机理及规律，获得覆膜区传热与温度分布、塑料膜熔化流动填充与界面真实贴合面积、辊压力与膜厚的影响因素及规律；研究建立高速覆膜过程与覆膜质量的关键控制技术，包括初始温度、基板表面微观形貌、辊压力的工艺要求和设定方法，塑料膜熔融厚度、辊压力、成品膜厚的预测计算方法及模型，辊压力与成品膜厚的控制策略与技术。为满足国内现有机组实现覆膜工艺速度大幅提高并保证高速高质量稳定覆膜生产，赶超国外先进水平，为我国自主研制覆膜铁产品提供理论指导和技术支撑。

随着金属包装工业逐渐向绿色、高端、环保方向发展，金属制品表面的涂镀技术越来越受到重视。.本课题选取镀铬板和PET薄膜作为原材料，进行了低速原理性覆膜实验。通过对制备的覆膜铁样品进行结合率检测实验、微米划痕实验、盐雾试验，分别研究了覆膜工艺参数与覆膜铁界面真实贴合面积、膜铁界面结合强度和薄膜耐腐蚀性能之间的相互影响关系。.建立了覆膜过程传热模型。指出覆膜辊初始预热温度和基材带钢初始预热温度是决定覆膜铁熔化层膜厚的主要工艺参数；覆膜辊和带钢初始预热温度增大都会使得熔化层膜厚变厚，但过大的覆膜辊和带钢初始预热温度也会使得覆膜铁薄膜完全熔化；建立了相应的熔化层膜厚预测模型，模型精度大幅提高最大误差不超过2.74%。.使用分子动力学结合第一性原理的方法从微观分子结合角度研究了Cr2O3分子与PET分子间的结合机理。结果指出氧化铬与PET分子间以酸碱相互作用的形式进行复合，Cr2O3 (110)、(200)、(211) 和PET分子间的结合能分别为13.07eV、-2.74eV、-2.37eV。对Cr2O3(200)表面进行羟基化处理，指出PET与羟基化氧化铬表面以生成氢键的方式进行结合，两者结合能随着羟基浓度的升高而增大。提出增加TFS表面羟基浓度是提高覆膜铁界面结合强度的有效措施。.建立结构-工艺相耦合的覆膜过程动力学分析模型，通过变固有特性分析可知：覆膜系统的固有频率较高，覆膜过程的工作频率引起共振可能性较小，但来自冷轧的板坯厚差缺陷以及覆膜辊的偏心都会引起强迫振动。基板温度若太高会带来填充率不足的问题；覆膜速度太高带来较严重的振动问题，但覆膜速度太低会影响填充率，因此覆膜速度成为覆膜铁生产过程中一个重要的工艺因素。.考虑基板板坯厚差缺陷与覆膜辊偏心的外激扰动作用，可以得到不同基板温度下以及不同覆膜速度下基板纵向厚差及偏心会引起辊压力产生显著的慢变周期性动态波动，且波动幅度可达40%以上，当工艺条件突变或控制不稳时更会导致辊压力的急剧变化，对覆膜效率及覆膜质量产生较大影响。相关技术成果为企业带来了一定的经济效益。