Development of steam injection drying method for lumber.

木材蒸汽喷射干燥方法的开发。

• 批准号: 14360096
• 负责人: HATTORI Nobuaki
• 金额: $ 9.34万
• 依托单位: Tokyo University of Agriculture and Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14360096/
• 关键词: Laser; Incising; Beam expander; Drilling; Aspect ratio; Post; Super steam; Drying; スギ; スチームインジェクション; 蒸気噴射

We developed the steam injection drying method in which super steam of over 100' was injected into laser incised holes of lumber. This new type of drying is supposed to be able to heat and dry whole lumber rapidly and evenly compared to conventional kiln drying. Furthermore, decompression and dehydration of water in lumber is supposed to happen by Bernoulli's theory. We also inspected whether a beam expander can control the shape of a hole or not. The results obtained in this research were as follows.1.We designed and made a jig for steam injection drying in order to prevent a leak of steam from a gap caused by shrinkage of lumber under fiber saturation point in moisture content. As the results, we could dry lumber to 15 % in moisture content without the leak of steam. Drying check was seen in lumber after quick drying. Therefore, a drying schedule must be developed even for this method to achieve a perfect drying.2.Drying speed increased with the laser incising density but the efficiency was doubled in case of lumber with four times of incising density. Therefore, it became clear not to raise the incising density blindly.3.The drying speed decreased only in case of incising pattern whose interval ratios are 1:2 and 1:5 for longitudinal and lateral directions. This phenomenon could not found both in higher and lower incising densities such as 2,000 holes/m^2 or 500 holes/m^2.4.The incising density of 1,000 holes/m^2 was most effective for perfect drying of lumber within this research.5.When an input diameter of a laser beam to a lens is expanded twice or three times compared to that of the original one with the beam expander made by this fund, a more slender hole could be made, though the depth of focus was shallow. Therefore, this technique is found to be more suitable for the laser incising of a lamina for glue lam.

我们开发了蒸汽喷射干燥方法，将超过 100 英尺的超级蒸汽注入木材的激光切割孔中。与传统的窑炉干燥相比，这种新型干燥方式应该能够快速、均匀地加热和干燥整块木材。此外，根据伯努利的理论，木材中的水会发生减压和脱水。我们还检查了扩束镜是否可以控制孔的形状。本研究取得的成果如下： 1.为防止木材在纤维饱和点含水率下收缩而导致蒸汽从缝隙中泄漏，设计并制作了注蒸汽干燥夹具。结果，我们可以将木材的含水量干燥至 15%，而不会泄漏蒸汽。快速干燥后，可以在木材中看到干燥痕迹。因此，即使是这种方法，也必须制定干燥计划以实现完美的干燥。2.干燥速度随着激光切割密度的增加而增加，但在切割密度为四倍的木材的情况下，效率加倍。由此可见，不能盲目提高切割密度。3.只有在纵向和横向间隔比为1：2和1：5的切割图案的情况下，干燥速度才会降低。这种现象在较高和较低的切割密度（如 2,000 孔/m^2 或 500 孔/m^2.4）中都不会出现。在本研究中，1,000 孔/m^2 的切割密度对于木材的完美干燥最为有效。5.当使用本基金制造的扩束器将激光束到透镜的输入直径与原始直径相比扩大两倍或三倍时，可以得到更细长的孔。 尽管焦深很浅，但已完成。因此，发现该技术更适合用于胶合层压板的层板的激光切割。