凹印机热风干燥箱射流场数值计算与分析

Jet Flow Field Numerical Calculation and Analysis on Hot-air Drying Oven of Gravure Press

中文关键词: 干燥机理  热风干燥  数值仿真  多物理场分析

英文关键词: drying mechanism  hot-air drying  numerical simulation  multiphysics field analysis

中文摘要:

      目的 研究凹版印刷机热风干燥系统的工作特性， 确定最佳干燥工艺参数。方法 以FR400凹印机干燥装置为研究对象， 从油墨溶剂阶段性挥发的干燥机理出发， 建立多束气体冲击平面射流干燥模型；通过Fluent完成干燥箱的流体场数值计算， 基于干燥箱几何结构研究热风的复杂流动状态， 分析湍流产生原因及对干燥效果的影响； 通过数值切片技术， 提取印刷品表面热风速度和温度值， 研究干燥参量波动的范围和特征， 讨论不同位置处热风不均匀特征和产生机理， 以及不同区域干燥过程中风速和温度的变化特征。结果 干燥箱左腔体导流板两侧及右腔体上端产生湍流， 风嘴之间形成了间隔分布的涡流区域； 干燥箱中间区域风嘴的热风速度较为均匀， 上、 下两侧较差， 中后部风嘴处热风温度较高， 左侧区域效果较差。结论 热风干燥系统的几何结构对干燥效果的影响显著， 合理的干燥箱结构设计和印刷图文布置有利于印品的干燥， 为干燥系统优化改进与创新设计提供了依据。

英文摘要:

      The aim of this study was to master characteristics of hot-air drying system, and obtain optimal drying technological parameters. Taking drying device of FR400 gravure press as the research subject, the paper researched drying and volatilizing mechanism of solvent in different stages, and established the multi-beam air impacting drying model for suspended hot-air drying device. The paper completed hot-air flow numerical simulation for drying cabinet through fluent, researched hot-air flow state based on structure of drying cabinet, and analyzed generation reasons of turbulence and the influence on drying effect. Air velocity and temperature on surface of presswork were extracted through numerical section technology, fluctuation range and features were analyzed, unevenness in different locations and the causes were discussed, and features of changes in velocity and temperature during the drying process were analyzed. Turbulence was generated on two sides of deflector in the left chamber and the upper right chamber of drying cabinet, and vortex region was formed between tuyeres in interval. The hot-air velocity was more even in the middle but worse at upper and lower sides; the temperature in tuyeres was higher in the middle and at the back, and the drying process was worse in left region. The geometric structure of hot-air drying system has a great influence on drying effect, and the reasonable design on drying cabinet and layout of the graphic area is conducive to drying of printing.