Study On Heat-Conduction Of Dry-Process Fiberboard In The Hot-Pressing Process

Hot-pressing method was adopted to make dry-process fiberboard, and the temperature of the center layer of mat was measured continuously and automatically by advanced instrument in the hot-pressing process. Based on the analysis of the curves of temperature changing, some basic laws as follows of hot-pressing heat-conduction of dry-process fiberboard was summarized: (1)The curves of temperature changing of mat's center layer were obviously divided into three stages, while when the density of panel was very high, the curves had four stages; (2)The influence of the original temperature of mat, high or low, to the time spent to heat the center layer to the curing temperature could be neglected;(3)Contact pre-heating to mats did not have effective function to heat-conduction in the hot-pressing process;(4)Thickness of panels and hot-pressing temperature impacted heat-conduction in the hot-pressing process of dry-process fiberboard greatly. Moisture content of mats, density of panels, form and property of fiber affected heat-conduction in the hot-pressing process at different degree; (5) Humidifying treatment in mat surface could shorten the time spent to make the center layer reached to water vaporizing temperature;(6) Humidifying treatment in mat surface could shorten a half time when the temperature of core layer reached to water vaporizing temperature at most. In addition, under four suppositions, ideal mathematic model of heat-conduction in the process of hot-pressing was deduced. Furthermore, practical mathematic model of heat-conduction in the process of hot-pressing of dry-process fiberboard was established, validated and perfected, which had a high simulative precision and could simulate accurately curves of temperature changing of mat's center layer under different conditions. The practical model can be used to forecast the time spent to heat center layer to a certain temperature under various conditions.