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Optimization of drying condition for boxed-heart timber by two displacement meters
The boxed-heart timber from sugi (Cryptomeria Japonica D. Don) are used widely as structural columns for traditional wooden houses in Japan. It is well recognized that the boxed-heart timber, which has a pith, is susceptible to serious drying checks. A new drying method called "High temperature drying set method", which forms drying set purposely at the surface of boxed-heart timber by heat treatment, is used to reduce the surface checks in many sawmills during recent years in Japan. Typical condition of the heat treatment for sugi timber is 120 °C of DBT and 90 °C of WBT, 12 -24 hours of treatment time. But properties of sugi vary in different varieties, tree age, and growing district. Hence dry kiln operators have to optimize the heat treatment condition for the timber they should dry through a trial and error process. If the best condition of heat treatment can be determined automatically in the factory, dying cost should be reduced and the quality of timber should be improved. The experiment uses two displacement meters to measure strains at the center and the marge of the surface of the boxed-heart timber from sugi (650 x 110 x 110 mm) during heat treatment and drying process. The shrinkage at the center of the surface delayed behind the marge. Probably because (1) the drying set was made at the marge of the timber, (2)the internal layer inhibited the shrinkage of the surface , (3) the shrinkage of the internal layer accelerated the shrinkage of the surface. The effectual heat treatment time to inhibit drying checks of the boxed-heart timber could be determined by the detection of the difference of strain behaviors at the center and the marge of the surface.
Optimization of drying condition for boxed-heart timber by two displacement meters
The boxed-heart timber from sugi (Cryptomeria Japonica D. Don) are used widely as structural columns for traditional wooden houses in Japan. It is well recognized that the boxed-heart timber, which has a pith, is susceptible to serious drying checks. A new drying method called "High temperature drying set method", which forms drying set purposely at the surface of boxed-heart timber by heat treatment, is used to reduce the surface checks in many sawmills during recent years in Japan. Typical condition of the heat treatment for sugi timber is 120 °C of DBT and 90 °C of WBT, 12 -24 hours of treatment time. But properties of sugi vary in different varieties, tree age, and growing district. Hence dry kiln operators have to optimize the heat treatment condition for the timber they should dry through a trial and error process. If the best condition of heat treatment can be determined automatically in the factory, dying cost should be reduced and the quality of timber should be improved. The experiment uses two displacement meters to measure strains at the center and the marge of the surface of the boxed-heart timber from sugi (650 x 110 x 110 mm) during heat treatment and drying process. The shrinkage at the center of the surface delayed behind the marge. Probably because (1) the drying set was made at the marge of the timber, (2)the internal layer inhibited the shrinkage of the surface , (3) the shrinkage of the internal layer accelerated the shrinkage of the surface. The effectual heat treatment time to inhibit drying checks of the boxed-heart timber could be determined by the detection of the difference of strain behaviors at the center and the marge of the surface.
Optimization of drying condition for boxed-heart timber by two displacement meters
Kobayashi, Isao (author) / Kuroda, Naohiro (author)
2013
6 Seiten, Bilder, Tabellen, 3 Quellen
Conference paper
English
Improving Drying Boxed-Heart Lumber Using the Perforation Method
| British Library Conference Proceedings | 1997
| British Library Online Contents | 1992
| Engineering Index Backfile | 1941