| 摘要 |
PROBLEM TO BE SOLVED: To obtain a method for hot air drying a timber for eliminating a temperature control function needed in a conventional means by stably preventing a check during drying and even after the drying for a tree type difficult to prevent the check by shortening a drying time of the timber. SOLUTION: When the timber is dried, the timber is dried in combination of vacuum conditions suitable for the tree type to be dried or a timber thickness in ranges of 30 to 700 Torr of vacuum and 25 to 90 deg.C of a hot air temperature and the hot air temperature. A moisture diffusion capability in the timber is utilized by a pressure reduced state without temperature control, and a drying period is shortened while suppressing a crack. At a drying initial time, in a material having an easy crack or a large sectional area, its moisture in the timber is diffused while suppressing a moisture evaporation from a timber surface layer by circulating the hot air of a temperature range of a boiling point corresponding to its vacuum area to a temperature lower by about 15 deg.C lower than the point.
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