Deep boring of structual laminated wood for bolt joint

最近在日本可以看到许多用结构层压木建造的木结构建筑。在这种结构中，采用螺栓联接，用长钻头钻出许多深孔。制造厂家指出了一些问题，如钻孔弯曲等，本文在研制了实验装置的基础上，对结构层压板长钻深孔钻孔弯曲问题进行了研究。从实验结果来看，虽然这种最深为300 mm的工作材料的弯曲度随着每转进给量的增大而增大，但其弯曲程度与平方的花旗松木材相比要小一些。在方形花旗松木材中，随着木材横截面上年轮与孔面的夹角和每转进给量的增大以及钻孔深度的加深，钻孔的弯曲度变大。因此，结构层压板的钻孔弯曲现象受木材横截面上年轮与孔面夹角的影响不大，因为这种工作材料是由树皮侧和髓侧交替叠合而成的。那么，由于我们在本实验中证实了钻头在钻削过程中的极限跑出受刀具硬度的影响，并且随着钻孔深度的增加，排屑变得更加困难，所以我们想要设计出具有高刚性和平稳排屑的长钻头。

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.