大片刨花板热压的传热过程

Heat-transfer process during hot-pressing of flakeboard.

该文研究了各工艺因素 (热压温度、初含水率、目标厚度和目标密度 )对大片刨花板热压传热过程的影响 .试验采用温度传感器测量板坯芯层的温度 ,通过计算机数据采集系统 ,在大片刨花板热压全过程中实现对板坯内部温度动态的实时纪录 .试验结果表明 :①板坯芯层的温度变化可划分为 3个阶段 (快速升温段、水分集中汽化段和慢速升温段 ) ;②在快速升温段 ,提高热压温度和增大初含水率均能加快板坯的升温 ,目标厚度小或目标密度低的板坯升温速率更快 ;③在水分集中汽化段 ,通过提高热压温度和减少初含水率均能缩短汽化时间 ,目标厚度小或目标密度低的板坯汽化时间更短 ;④在慢速升温段 ,初含水率对这个阶段几乎没有影响 ,其他因素对这个阶段的影响类似快速升温段 ;⑤不同热压工艺条件下 。

Hot-pressing is the key process in flakeboard manufacture. Studies in this field also emphasize the influence on the heat-transfer process of the following factors: temperature of hot-plates, original moisture content (MC), target thickness and target density. In this experiment, dynamic data of temperature changes of the core can be logged through a temperature transducer and computer data log system. The results of the experiment indicate that the core temperature-time curve can be divided into three stages: a stage of a rapidly rising temperature, a stage of moisture vaporizing and a stage of a slowly increasing temperature. If the temperature of the hot-plates or the original MC increases during the first stage, the rate of increasing temperature will accelerate. This rate of acceleration in thin or low density board is very high. During the second stage the time used to vaporize moisture can be shortened by increasing the temperature of the hot-plates or decreasing the original MC. In thin or low density board this time period is short. In the third stage the original MC has no influence on the rate of increasing temperature, while the influence of the other factors is the same as in the first stage. Under different conditions, vaporization temperatures in the mat change.