【作者】 程秀才；

【导师】 张齐生； 胡启龙；

【作者基本信息】 南京林业大学 ， 木材科学与技术， 2009， 博士

【摘要】 本篇论文对胶合板热压过程和低温状态的传热性能以及低温状态的弯曲力学性能进行了研究,得出以下结论:(1)胶合板热压过程中心层温度变化曲线基本可以根据热压时间分为短暂恒温、快速升温、水分汽化恒温和慢速升温四个阶段;胶粘剂种类、施胶量、单板材种、纹理排列方式和板坯密度对胶合板的热压传热过程影响很小;单板含水率、板材厚度和热压板初始温度对胶合板热压传热影响比较显著。(2)胶合板在低温状态的冷却过程可以分为快速降温和减速降温两个阶段;升温过程可以分为开始阶段、快速升温和升温速度减缓三个阶段;胶粘剂种类、施胶量、单板材种和纹理排列方式对胶合板低温状态冷却过程和升温过程的传热性能影响很小;含水率、板材厚度和密度对胶合板低温状态传热性能有影响。(3)可以分别采用马尔萨斯(Malthus)模型、线性模型和幂函数模型模拟的方式对胶合板热压过程和低温状态的传热性能进行数学模拟。(4)低温处理(-196℃,48h)对胶合板的弯曲力学性能有降低效应;低温状态(-196℃)对胶合板弯曲力学性能有增强效应;板材含水率对胶合板低温状态弯曲力学性能有显著影响;胶合板在三种不同状态下MOR和MOE之间具有很好的相关性;可以利用胶合板的MOE二次多项式函数关系式来预测胶合板的MOR数值。(5)以MOR∥、MOR⊥、MOE∥和MOE⊥的测试数值作为考察对象,对桦木胶合板在三种状态条件下的弯曲力学性能进行了统计分析,结果表明胶合板的弯曲力学性能能够较好的符合概率正态分布和威布尔分布数学模型。更多还原

【Abstract】 In this paper, heat-conduction during the process of hot pressing and in low temperature of plywood were tested and analyzed; the bending performance of plywood in low temperature was researched. The results showed:(1)The curves of temperature changing of mat central layer during the process of hot pressing were obviously divided into four stages. Adhesive types, resin content, wood species and fibred form affected heat-conduction during the process of hot pressing indistinctively. Thickness of panel, moisture content of veneer and the original temperature of mat impacted heat-conduction greatly.(2)The curves of temperature changing of mat central layer during the process of refrigeration by low temperature were divided into two stages. The curves of temperature changing of mat central layer during the process of calefaction by low temperature were divided into three stages. Adhesive types, resin content, wood species and fibred form affected heat-conduction in low temperature indistinctively. Thickness of panel, moisture content of veneer and density of mat impacted heat-conduction in low temperature greatly.(3)The heat-conduction of plywood during the process of hot pressing and in low temperature could be simulated by Malthus model, Liner Function and Power Function.( 4) Bending performance of plywood descended after treated with low temperature. Bending performance of plywood was enhanced by low temperature. Moisture content of plywood impacted bending performance in low temperature greatly. The relativity of MOR and MOE was remarkable. The MOR values of plywood could be doped out by 2-Polnomial Function.(5)To analyze statistically the bending performance of plywood in different states, the MOR∥、MOR⊥、MOE∥and MOE⊥of plywood were researched Statistically in this paper. The results showed that the bending performance of plywood was in line with Normal distribution and Weibull distribution.更多还原