Sugi Rotary Veneers Compressed by Hygro-Thermal Treatment with an Airtight Device Using Moisture in the Veneers
Xianghua YI, Nobuyuki KINOSHITA, Masahiro YOSHINOBU and Huiyuan GUAN
Abstract:Sugi(Cryptomeria japonica) rotary veneers with thickness of 3.5 mm were compressed in the radial direction using the moisture content in the veneers enclosed in an airtight device set on a hot-press to improve its mechanical properties. The compressive deformation of the rotary veneers with moisture contents of 30 % or more were approximately fixed by the compression at 200 C for 3 minutes or 180 C for 8minutes: These conditions for permanent fixation of the rotary veneers were similar to those of Sugi sawed veneers. The resistance of surface to wear of the compressed rotary veneers was 2 times higher than those of the uncompressed veneers. The dynamic Young's modulus in the longitudinal direction of the rotary veneers increased with an increase in degree of compression. These improvements in the resistance of surface to wear and dynamic viscoelasticity in the longitudinal direction of the rotary veneers were similar to those of the sawed veneers and resulted from increased in density by compression. The dynamic Young's modulus in the tangential direction of the rotary veneers, however, scarcely increased by compression and was much less than that of the compressed sawed veneers. The specific dynamic Young's modulus in the longitudinal direction of the compressed rotary veneers also increased due to an increase in density by the compression, whereas that of the compressed sawed veneers did not vary. It was thought that the difference in the behavior of the specific dynamic Young's modulus between the rotary veneers and the sawed veneers was due to the lathe checks that existed only in the rotary veneers, that is, the compression disappeared from both of the voids of the cells and those caused by the lathe checks for the rotary veneers but disappeared only from the voids of the cells for the sawed veneers. Key Words:Sugi rotary veneer, Compression, Airtight device, Hygro-thermal treatment, Resistance of surface to wear, Recovery of set, Specific dynamic Young's modulus, Lathe checks, Sugi sawed veneer