A Developmental Study of Drying System Applying RF-Heating/Vacuum Method to The Boxed-Heart Heavy Timbers Like Logs.
| Project/Area Number |
08556029
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
林産学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
MATAKI Yoshihiro Kyushu University, Agriculture, Professor, 農学部, 教授 (50038212)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIMOTO Noboru Kyushu University, Agriculture, Assistant, 農学部, 助手 (80238617)
TANIGUCHI Yoshiaki Nara University of Education, Professor, 教育学部, 教授 (50240859)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥10,900,000 (Direct Cost: ¥10,900,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥4,900,000 (Direct Cost: ¥4,900,000)
Fiscal Year 1996: ¥5,400,000 (Direct Cost: ¥5,400,000)
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| Keywords | RF / Vacuum drying / boxed-heart square timber / log / surface check / internal stress / drying set / kiln-drying / transpirational drying / 葉枯らし材 / 高周波加熱乾燥法 / 乾燥速度 / 乾燥応力 / 心持ち角材 / 高周波加熱乾燥 / 熱風-高周波加熱併用乾燥 / 割れ / 高周波加熱減圧法 / 蒸気式乾燥 / スギ丸太 / 心待ち大断面材 |
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| Research Abstract |
In Japan, sugi is very often used as a boxed- heart timber of log or square column. It is difficult to dry these timbers in a short time, as having a big cross section and large aria of heart wood. It connects with the increase of the drying cost. And the severe checks occur easily for the boxed heart timbers of sugi during drying , because of anisotropic shrinkage. RE/vacuum drying method is wellknown for an effective means of rapid and checkless drying. But When the moisture distribution became approximately uniform after drying, surface check often occurred.
In this research, measurment of internal stress and drying set was performed on the sugi log and boxed-heart square timber dried with RE/vacuum method and it's combination with heat treatment or transpirational drying. As a result of these investigations, it became clear as follows. (1) These stresses of Sugi logs dried with RE/Vacuum method were relatively large tension , when the moisture distribution in the cross section became approximately uniform after drying. By the heat treatment of 80ﾟC for 1 day, these large tensile stresses at the surface layer disappeared and surface checks were improved. (2) The conbination method of kiln- drying and RE/Vacuum drying improved these drying time and surface check for the boxed-heart square timbers. It seems that one of the reason for surface check decrease is drying set made at the former stage of kiln- drying. (3) By the transpirational drying, moisture content of only sap wood was decreased. So the moisture contents of outer part in the cross section of the boxed-heart square timbers became approximately lower than inner part during RE/Vacuum drying, and surface checks were decreased comparing with untreated.
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Report
(4 results)
Research Products
(15 results)
