Deep boring of structual laminated wood for bolt joint

最近在日本可以看到许多由结构层压木制成的木结构建筑。该结构采用螺栓连接，并用长钻钻出许多深孔。生产厂家指出了在钻孔过程中存在的一些问题，如钻孔歪斜等。本工作在制作实验装置后，对结构层合木长钻深钻时钻孔的弯曲进行了检测。从实验结果来看，该孔最深为300mm的工作材料，虽然随着每转进料量的增大，弯曲程度也随之增大，但与方木相比，弯曲程度较小。在方木杉木中，随着年轮与木材横截面上钻孔面夹角和每转进给量的增大以及钻孔深度的加深，钻孔的弯曲度也随之增大。由此得出结论，结构层合木材的钻孔弯曲现象受木材横截面上年轮与钻孔面夹角的影响不大，因为该工作材料是由树皮侧和髓侧交替层合而成。由于我们在本次实验中证实了钻孔过程中钻头的极值出钻受刀具刚度的影响，并且随着钻孔深度的加深排屑难度增大，所以我们想设计出高刚性、排屑顺畅的长钻头。

Many wooden structures by structural lamineted wood can be seen in Japan recently. In this structure, bolt joint is adopted and many deep holes are bored with long drill. Some problems, for instance, the crook of bored hole and so on have been pointed out by manufacturing factory.In this work, after we made experimental apparatus, we examined about the crook of bored hole in the deep boring of structural laminated wood with long drill. From the experimental results, although the crook of this work material with the deepest hole of 300mm became larger as the feed per revolution became larger, the degree of it was small as compared with that of squared Douglas-fir timber. In the square Douglar-fir timber, the crook of bored hole became larger as both angle of annual rings to bore surface on cross section of wood and feed per revolution became larger and as the depth of boring hole became deeper. Hence it was concluded that the crook phenomenon of bored hole of structural lamineted wood was not affected by the angle of annual rings to bore surface on cross section of wood very much because this work material was made by laminationg bark side and pith side alternately. Well, as we confirmed in this experiment that the run out of drill's extreme during boring was affected by tool rigidity and the exhaust of chip became more difficult as the depth of boring hole became deeper, we want to design long drill with high rigidity and with smooth exhaust of chip.