Mechanism of Strength of Nailed Joints Using Auto-nailers

自动打钉机的发展带来了打入钉安装的重大进步。这种动力设备的使用大大提高了速度。目前对自动打钉机的基础研究主要集中在打钉机的工作机理上，而对自动打钉机钉头的力学性能研究较少。本研究的主要目的是探讨自动钉枪与锤击钉合的拔出强度与侧向强度。1.拔出强度：主要目的是验证钉合劈裂木材与拔出强度之间的关系。扫描电镜研究表明，较高的驱动速度会导致较大的劈裂。一个既定的理论认为，大劈裂降低了拔出强度，但相反，拔出强度与钉劈面积成正比。环柄钉对木材的破坏作用显著，动力驱动和锤击驱动的拔出强度差异较小.横向强度：采用X射线照射研究横向强度。结果总结如下。1)气炮驱动钉头的抗侧力与锤击驱动钉头的抗侧力基本相同。但动力驱动的钉子使用塑料片连接应在未来进行研究。2)由于环钉对木材的破坏作用显著，其抗侧力小于光钉和螺纹钉，验证了动力驱动钉连接的力学性能。我想在这个领域进行进一步的研究，并开发新的类型钉。

Major advances in the installation of driven nails has been brought about by the development of auto-nailers. The use of such power equipment greatly increases the speed. The basic research on auto-nailer has focused on the mechanism of the machine and the research on the mechanical properties of the nailed joints was very few. The main objective of this research is to investigate the withdrawal strength and lateral strength of nailed joints driven by auto-nailers and hammer.1.withdrawal strength : The prime object is to verify the relationships between split of wood by nailing and withdrawal strength. According to the research by scanning electron micro-scope , higher speed driving caused larger split of wood . An established theory says that large split decreased the withdrawal strength but on the contrary withdrawal strength was proportional to the area of split of wood by nailing . Ring shank nails damaged the wood significantly so the difference of withdrawal strength between power driven and hammer driven was small.2. Lateral strength : Lateral strength was investigated with X-ray irradiation. The results were summarized as follows. 1) Lateral strength of nailed joints driven by pneumatic guns was almost the same as that of hammer driven nailed joints . But the nails for power driven were connected using plastic sheets should be studied in the future. 2) Since ring nails damaged the wood significantly, the lateral strength was smaller than that of smooth shanked nails and screw-shanked nails This study verified the mechanical properties of power driven nailed joints . I would like to proceed further studies in this field and develop new type nails.