広瀬 英雄 北見木材株式会社, 代表取締役(研究職)
KUGA Shigenori Grd.School of Agr.& Life Scis., The Univ.of Tokyo, Biomaterial Sci., Associate P, 大学院・農学生命科学研究科, 助教授 (60012051)
WADA Masahisa Grd.School of Agr.& Life Scis., The Univ.of Tokyo, Biomaterial Sci., Assistant P, 大学院・農学生命科学研究科, 助手 (40270897)
HIROSE Hideo Kitami Mokuzai Co., President
|Budget Amount *help
¥8,600,000 (Direct Cost : ¥8,600,000)
Fiscal Year 1998 : ¥2,900,000 (Direct Cost : ¥2,900,000)
Fiscal Year 1997 : ¥5,700,000 (Direct Cost : ¥5,700,000)
Five Picea woods, (1)Picea complanata (phi : 66cm and total annual ring number : 141, 50cm and 141), (2)P.balfourniana (62cm and 350, 62cm and 387), (3)P asperata(54cm, and 152), (4)P.purpurea (80cm and 291, 54cm and 304), and(5)P.likiangansis (54cm and 216, 62cm and 293) were collected in Sichuan province, China and another one, (6)P.koraiensis was given by Professor Liau, South-cast Forestry University, China. Vibrational properties were examined and then light microscopic observation and x-ray diffraction analysis were carried. The aim of this research is to find better quality of wood for musical instruments, especially for piano. At present all the Picea woods have been imported from China named 'kumosugi', as the result there is a big confusion in evaluation of those woods by piano makers, and some woods might be wasted.
Lumbers that were selected at Chuanya Wood Industry Co., Ltd. were cut into a certain thick boards that include the pith and dried. Then, they were imported by ai
Dynamic Young's modulus, rigidity and tangent loss were estimated based on Timoshenko's equation using 1st to 7th vibration modes. Test specimens for light microscopic observation and x-ray diffraction analysis were manufactured from some typical specimens for vibration test.
Results of comparison of the evaluated values with those of sitka spruce (Picea sitchensis) were ; the density of(2) and (3)is lower than sitka spruce, all the specific longitudinal Young's modulus was lower, specific radial Young's modulus of(1), (3) and (6)was smaller, tangenf loss in the radial direction was larger 30 to 50% than that of sitka spruce. Er/Gr a significant index for soundboard and larger value is preferable, distributed in a wide range among the woods, and differed even between the same species.
It is concluded that there were very few species better for soundboard, but some was seemed to be excellent. If we can easily identify those of good quality wood, then a superior piano will be manufactured with Chinese spruce wood. Less