Mechanism of Strength of Nailed Joints Using Auto-nailers

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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.