桉树无性系大径材干燥特性分析

Drying characteristics of Eucalyptus clones with large-diameter

  • 摘要: 目的分析桉树无性系大径材的干燥特性,并预测其干燥基准,为桉树大径材的实木利用提供科学依据.方法采用百度试验法研究10年生尾巨桉无性系大径材的干燥特性,根据木材干燥过程中初期开裂、内部开裂和截面变形3项干燥缺陷的发生程度,制定桉树大径材干燥基准.结果桉树无性系大径材初期开裂程度2级;内部开裂程度中等,为3级;截面变形严重,为4级.干燥速度为4级,干燥速度较慢,属难干木材.体积、径向和弦向干缩率较大,分别为19.656%、10.976%和9.451%;差异干缩值为0.861,属差异干缩小.根据3种缺陷的等级程度,确定桉树无性系大径材干燥基准的基本条件:初期温度50℃,初期干湿球温度差2~4℃,末期温度75℃;厚度为25~30 mm的桉树无性系木材窑干至水含率10.00%所需时间为20.75 d.结论截面变形是桉树无性系大径材的主要干燥缺陷,为防止其发生,在生产中应以初期温度50℃、初期干湿球温度差2~4℃、末期温度75℃为干燥基准,可根据实际情况进行适当调整.

     

    Abstract: ObjectiveIn the present paper, drying characteristics of Eucalyptus clones with large-diameter were studied, and the drying schedule was predicted, in order to provide scientific basis for the utilization of Eucalyptus big-diameter wood. MethodDrying characteristics of 10-year-old Eucalyptus clones with large-diameter were studied by 100℃ test method. On the basis of drying defects, namely initial crack, internal crack and cross-section deformation during wood drying process, the drying schedule of Eucalyptus big-diameter wood was proposed. ResultThe initial crack was grade 2;internal crack degree was moderate, being grade 3;degree of cross-section deformation was serious, being grade 4. Drying speed was grade 4, which meant the drying speed was slow and Eucalyptus a the wood dried slowly. Volume dry shrinkage rate(19.656%), radial dry shrinkage rate(10.976%) and tangential dry shrinkage rate(9.451%) were large;difference dry shrinkage(0.861) was small. According to the grades of the three defects, the basic conditions of drying schedule were as follows:under the condition of initial temperature 50 ℃, difference between wet and dry bulb temperatures at initial period 2-4℃, temperature at late drying period 75℃, it took 20.75 d to dry Eucalyptus clones with large-diameter with 25-30 mm thickness to 10.00% moisture content. ConclusionThe main defect is section deformation. In order to avoid it, the dry-ing schedule should be initial temperature 50℃, difference between wet and dry bulb temperatures at initial period 2-4℃, temperature at late drying period 75℃in actual production. This schedule can be adjusted based on specific condition.

     

/

返回文章
返回