大片刨花板热压板坯内部气压变化的研究  

Gas pressure in mat during hot-pressing process of flakeboard.

作　　者：吴娟[1] 于志明[1] 陈天全[1] 

机构地区：[1]北京林业大学材料科学与技术学院

出　　处：《北京林业大学学报》2009年第S1期131-135,共5页Journal of Beijing Forestry University

基　　金："十一五"国家科技支撑计划项目(2006BAD18B0904);"948"国家林业局引进项目(2006-4-106)

摘　　要：热压过程中板坯内部气压的变化对产品的质量有着重要的影响,掌握气压的变化规律,可以从根本上避免"分层鼓泡"现象的发生。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)对大片刨花板热压板坯内部气压变化的影响。试验采用温度和压力传感器测量板坯的中心温度和中心气压,在热压全过程中通过计算机数据采集系统对板坯中心实现温度和气压动态的实时纪录。结果表明:①板坯中心压力由水蒸气分压和空气分压组成,其中水蒸气分压的变化对中心压力变化的影响最大;②中心温度越高,蒸汽分压越大,形成的中心气压也越大;③板坯中心在水分集中汽化阶段获得最大气压,取得最大气压时对应的温度与水分集中汽化时的汽化温度一致;④热压温度高或目标密度大的板坯都能使最大压力达到较大值;⑤随着初含水率的增大,最大气压值并不一直增大。During the hot-pressing process of wood-based panels,changes of gas pressure in mat have great effects on the quality of final products.A thorough understanding of rules of gas pressure change could avoid 'drum' in the hot-pressing process.In this study,the effects of four factors,i.e.,hot-plate temperature,initial moisture content,target thickness and target density,on gas pressure change in the mat core were investigated.Dynamic data of temperature and gas pressure change in the mat core were logged by temperature transducers,pressure transducers and a computer data logger system.Results show that: 1) total gas pressure in the mat core was composed of partial vapor pressure and partial air pressure;2) the higher the temperature of the mate core was,the greater the partial vapor pressure and total gas pressure were;3) the maximum gas pressure was obtained at the intensive vaporization stage,so the corresponding temperature was the same as the vaporization temperature at this stage;4) a high value of maximum pressure could be obtained in mats with a high hot-plate temperature or a high target density;5) the value of maximum pressure did not always increase with the increasing initial moisture content.

关 键 词：大片刨花板 热压 板坯中心气压 温度 

分 类 号：TS653[轻工技术与工程]