Development of Continuous Steam-Injection Press

设计了一种带热板表面蒸汽喷射装置的连续压制系统，并对制造厚度大于50 mm的无极刨花板的可行性进行了研究。对注汽冲压的相关问题进行了基础研究。结果表明：1)试验安装的间歇式压机具有800mm（宽）× 1200mm（长）的注蒸汽压板，可沿颗粒垫流往复移动，与常规连续压机相比，间歇式压机更简单，更适应注蒸汽。2)采用140℃蒸汽注入10秒，热压80秒，可生产厚度为100 mm，密度为0.6 g/cm^3的刨花板。这种压印周期比传统热压快20倍。3)在某些情况下，相互压合处的结湿显著降低了内部粘结强度。但是，经过一定的生产（预热）后，冷凝水会在一定程度上消除。4)用有限元方法对压垫内的热扩散和温度分布进行数值分析，有助于预测压垫循环。5)高压注蒸汽作用下，每种树脂都有自己的凝结分解过程。尿素树脂的最佳固化时间范围最窄，苯酚和异氰酸酯树脂的最佳固化时间范围最宽。

A continuous pressing system with a device of steam-injection from the hotplatem surfaces was designed and feasibility of manufacturing endless particleboard with thickness more than 50 mm was investigated. Fundamental research on the related problems to the steam-injection pressing was also made. The sesults are summarized as follows:1) The press installed trially had steam-injection platens of 800 mm (width) x 1,200 mm (length) and could move reciprocally along the stream of particle mat. It was verified that this type of intermittent press was more simple and adaptable to the steam-injection than conventional continuous presses.2) Particleboard of 100 mm thickness and 0.6 g/cm^3 density was producible by this press with 10 sec 140 c steam-injection followed by 80 sec hot-pressing. This press cycle is 20 times faster than that of conventional hot-pressing.3) The moisture condensation at the joint part of reciprocal pressing reduced the internal bond strength remarkably in some cases. However, the moisture condensation would be eliminated in some extent after some contimuation of production (warming-up).4) Numerical analysis of heat diffusion and temperature distribution in the mat by the finite element method was useful to predict the press cycle.5) It was shown that every resin had its own process of condensation and decomposition under high pressure steam-injection. urea resin had the narrowest time range optimum curing, while phenol and isocyanate resin had the broadest.