超薄浮法玻璃拉薄行为数值研究

Numerical Study of Thinning Behavior for Ultra-thin Float Glass

拉薄行为认识对超薄柔性玻璃的合理制备具有重要指导作用。在分析薄浮法玻璃拉薄基本过程的基础上,运用数学模型、计算机技术研究了高碱铝硅玻璃的拉薄行为。研究发现,玻璃带拉薄主要发生在拉制温度后的前1/3区;在这一区域,表面张力和纵向牵引引起的横向收缩共同作用使玻璃带比低温拉薄(僵带模型)更容易发生横向收缩和厚度变厚,必须使用横向拉边机;调整玻璃带末端速度可以获得更薄的玻璃带,但玻璃带末端厚度的减小与玻璃带末端速度的增加并不呈线性关系。综合理论和技术考虑,超薄玻璃制备宜采用纵向拉伸与横向拉边相结合的方式,且超薄玻璃比普通浮法薄玻璃的横向拉边机宜布置得更密集些。拉制温度高低影响拉得既定厚度玻璃的纵向牵引力的大小,对高碱铝玻璃,第一对拉边机的位置宜放置在温度1050~1150℃处。“徐冷”拉薄工艺更适合超薄玻璃拉制。

The good understanding of thinning behaviors is crucial to the production of ultra-thin flexible float glass.The basic thinning process was first analyzed.Then the equations for momentum and mass conservation which describe the thinning behaviors were given and have been numerically solved on computer.The results show that the thinning processes mainly take place at the range of 0-1/3 whole length after the drawing temperature.And at this range,the surface tension and the transverse contraction force caused by longitudinal traction contribute together to the narrower width and the thicker thickness of glass ribbon comparing to stretching at lower temperature(stiff-ribbon model).Therefore,it is essential to using edge rollers in the transverse direction.An increase of glass ribbon velocity at the exit can cause a thinner glass thickness,but it does not exist linear relationship between the velocity and thickness of glass ribbon at the exit.It is a good way for the preparation of ultra-thin float glass by combining the longitudinal traction with the use of transverse edge rollers.The more pairs of edge rollers should be placed for ultra-thin flexible float glass.Drawing temperature has an influential effect on the longitudinal tractive force required for a given glass ribbon thickness at the exit.The first pair of edge rollers is suitable for placing at the range of 1050〜1150°C for ultra-thin high-alkali-alumino-silicate float glass.The"cooling down smoothly''technology is more feasible for the preparation of ultra-thin glass.